Authors:Jaesoon Jung; Junghwan Kook; Seongyeol Goo; Semyung Wang Pages: 1 - 15 Abstract: Publication date: October 2017 Source:Advances in Engineering Software, Volume 112 Author(s): Jaesoon Jung, Junghwan Kook, Seongyeol Goo, Semyung Wang In this paper, an accurate and efficient numerical method for sound transmission analysis is presented. As an alternative to conventional numerical methods, such as the Finite Element Method (FEM), Boundary Element Method (BEM) and Statistical Energy Analysis (SEA), the FE-ERA method, which combines the FEM and Elementary Radiator Approach (ERA) is proposed. The FE-ERA method analyzes the vibrational response of the plate structure excited by incident sound using FEM and then computes the transmitted acoustic pressure from the vibrating plate using ERA. In order to improve the accuracy and efficiency of the FE-ERA method, a novel criterion for the optimal number of elementary radiators is proposed. The criterion is based on the radiator error index that is derived to estimate the accuracy of the computation with used number of radiators. Using the proposed criterion a radiator selection method is presented for determining the optimum number of radiators. The presented radiator selection method and the FE-ERA method are combined to improve the computational accuracy and efficiency. Several numerical examples that have been rarely addressed in previous studies, are presented with the proposed method. The accuracy and efficiency of the proposed method are validated by comparison with the results of the three dimensional (3D) FEM structure-acoustic interaction models.
Authors:Benoit Bary; Christophe Bourcier; Thomas Helfer Pages: 16 - 30 Abstract: Publication date: October 2017 Source:Advances in Engineering Software, Volume 112 Author(s): Benoit Bary, Christophe Bourcier, Thomas Helfer We investigate in this paper analytically and numerically by means of 3D simulations the viscoelastic behavior of concrete and mortar subjected to creep loading and moderate temperatures at mesoscale. These heterogeneous materials are assumed to be composed of thermoelastic aggregates distributed in a linear thermoviscoelastic matrix; moreover, the Interfacial Transition Zones (ITZ) between aggregates and matrix, whose behavior is also considered as linear thermoviscoelastic, are explicitly introduced. The numerical specimens consist in unstructured periodic meshes containing polyhedral aggregates with various size and shapes randomly distributed in a box. Zero-thickness interface finite elements are introduced between aggregates and matrix to model the ITZ. Macroscopic response and averaged stresses and strains in the matrix and aggregate phases are compared to analytical estimations obtained with classical mean-field approximation schemes applied in the Laplace–Carson space, in which the ITZ are introduced via imperfect interfaces modeled with the Linear Spring Model (LSM). The effects of ITZ thickness, aggregate shape and uniform temperature increase are then studied to evaluate their respective influence on the local and macroscopic creep behavior of mortar and concrete. Globally, it is found that the model response is in relatively good agreement with numerical simulations results, and that as expected while the ITZ do not affect significantly the concrete behavior, they have a non-negligible impact on the mortar one.
Authors:R.L. Pedro; J. Demarche; L.F.F. Miguel; R.H. Lopez Pages: 31 - 45 Abstract: Publication date: October 2017 Source:Advances in Engineering Software, Volume 112 Author(s): R.L. Pedro, J. Demarche, L.F.F. Miguel, R.H. Lopez This paper presents an efficient two-stage optimization approach to the design of steel-concrete composite I-girder bridges. In the first step, a simplified structural model, usually adopted by bridge designers, is employed aiming to locate the global optimum region and provide a starting point to the local search. Then, a finite element model (FEM) is used to refine and improve the optimization. Through this procedure, it is possible to combine the low computational cost required on the first stage with the accuracy provided on the second one. For illustration purposes, a numerical example of a composite bridge designed by Pinho and Bellei (2007) and studied by Leitao et al. (2011) is assessed. The objective function is based on the material cost of the structure. Due to the non-convex nature of the problem and to the presence of discrete variables, the first stage optimization is conducted through five well-known meta-heuristic algorithms: Backtracking Search Algorithm (BSA), Firefly Algorithm (FA), Genetic Algorithm (GA), Imperialist Competitive Algorithm (ICA) and Search Group Algorithm (SGA). The SGA is chosen to pursue the second stage because a statistical analysis has shown that it achieved the best performance. It is shown that the proposed scheme is able to reduce the structural cost in up to 7.43% already in the first stage and can reach up to 9.17% of saving costs in the end of the optimization procedure.
Authors:Sara Casciati; Michele Vece Pages: 46 - 53 Abstract: Publication date: October 2017 Source:Advances in Engineering Software, Volume 112 Author(s): Sara Casciati, Michele Vece The real time estimation of the displacements of civil structures is quite sensitive to the availability of wired links between the sensors and the remote control room. Many kinds of wireless displacement sensors or indirect measurements of them have been proposed. However, most of them suffer of large time delays and accuracy issues. In this paper, the authors adopt a Kalman-filter-based data fusion to make a precise measurement of the displacements in for civil structures and infrastructures. The required accuracy can be reached exploiting the real-time satellite corrections provided by a single reference station and combining them with the acceleration signals coming from three axial accelerometers. A wireless communication transfers the information coming from the coupling of GNSS receivers and three axial accelerometers. The proposed system is validated by control mechanism and laboratory tests. The ultimate goal is a reliable scheme for a real-time structural health monitoring managed in remote control.
Authors:A.A. Kruglov; V.R. Ganieva; F.U. Enikeev Pages: 54 - 65 Abstract: Publication date: October 2017 Source:Advances in Engineering Software, Volume 112 Author(s): A.A. Kruglov, V.R. Ganieva, F.U. Enikeev The problem to determine experimentally the values of material parameters for two material models of superplastic flow, σ=Kξm and σ = K′ξ m′ε n , from the results of technological trials is considered. With this in view, a special computational procedure is developed to minimize the deviation of the theoretically predicted forming times from experimental data recorded during constant pressure forming trials of a sheet into a circular die. As compared with similar procedures known in the literature the methods suggested enable one to obtain a unique set of material parameters by using the whole set of available experimental data. The validity of the procedures suggested is confirmed by means of comparing the results obtained with corresponding finite element solutions. The accuracy of modeling of the experimentally measured values of the forming time is found to be better than 5% for all cases considered.
Authors:Shanghong Zhang; Wenda Li; Xiaohui Lei; Xiaowen Ding; Tianxiang Zhang Pages: 66 - 75 Abstract: Publication date: October 2017 Source:Advances in Engineering Software, Volume 112 Author(s): Shanghong Zhang, Wenda Li, Xiaohui Lei, Xiaowen Ding, Tianxiang Zhang Computer-based flow visualization, which is an important approach to examine both the dynamic flow process and to elucidate the laws of fluid movement, can greatly facilitate our understanding of the complicated hydrologic cycle and provide insights into regional water resources management. Nevertheless, at present, few software tools can efficiently perform different flow visualizations for watershed modeling. In this study, a virtual watershed platform was developed and various implementation methods of flow visualization were assessed, such as scalar field visualization, vector field visualization, and visual water effects. In the platform, spatially distributed flow model results and georeferenced datasets are visualized in a virtual 3D environment. End users can conveniently explore modeling results within that environment. Based on analysis of the varying requirements of the flow visualization methods applied to watershed simulation, overheads associated with a user-determined switch between different systems were reduced, and the level of comprehensive information management and analysis of large volumes of watershed data was improved. This study shows that application of the watershed platform can enhance flow visualization in the water resources research community, and makes related water modeling more practical in support of water resources management.
Authors:D. Dinh-Cong; T. Vo-Duy; V. Ho-Huu; H. Dang-Trung; T. Nguyen-Thoi Pages: 76 - 87 Abstract: Publication date: October 2017 Source:Advances in Engineering Software, Volume 112 Author(s): D. Dinh-Cong, T. Vo-Duy, V. Ho-Huu, H. Dang-Trung, T. Nguyen-Thoi The paper presents an efficient multi-stage optimization approach for damage detection in plate-like structures. In this approach, the damage identification process is achieved by minimizing an objective function established via flexibility changes of the structure. The vector of design variables represents correspondingly the damage extent of elements discretized by the finite element model. For analyzing the response of plate structures, the finite element model using 9-node quadratic quadrilateral elements is applied. For solving the optimization problem, a modified differential evolution (MDE) algorithm, which can help enhance the balance of global and local searches in each generation, is used for many stages of damage detection, in which the low damage variables in each stage are gradually eliminated after several generations to reduce the dimension of searching space and to increase the convergence rate of the problem. The efficiency of the proposed method is investigated through two numerical examples for isotropic and laminated composite plates. The obtained results indicate that the proposed method not only successfully detects the location and severity of multi-damage cases in the plate structures, but also show the better efficiency in term of computational cost.
Authors:Matthew Gutowski; Emre Palta; Howie Fang Pages: 88 - 100 Abstract: Publication date: October 2017 Source:Advances in Engineering Software, Volume 112 Author(s): Matthew Gutowski, Emre Palta, Howie Fang With an average of six billion miles traveled per day on U.S. highways, according to the Federal Highway Administration (FHWA), transportation safety is of the utmost importance. Over the years, various traffic barrier systems, including W-beam guardrails, have been developed to reduce the number and severity of vehicle crashes. Despite their general effectiveness, improvements could be made, especially when installed on unlevelled terrains such as sloped medians. The destructive nature of crashes imposes significant challenges to barrier design using full-scale physical testing; numerical simulations thus become a viable means to support crash analysis, performance evaluation, and barrier designs. In this study, validated vehicle and W-beam models were used to perform full-scale simulations of vehicle-guardrail impacts. Fourteen single-faced and double-faced NCDOT W-beam guardrails (with placement heights of 29 and 31 inches) placed along a six-lane 46-foot median divided highway with 2.5H:1V and 4H:1V slopes were evaluated under front-side and backside vehicular impacts. The guardrails performance was determined by evaluating the vehicular responses based on MASH exit-box criterion, post-impact exit trajectory, yaw, pitch, and roll angles, transverse displacements, and transverse velocities.
Authors:Seung-Ho Ham; Myung-Il Roh; Hyewon Lee; Jin-Wuk Hong; Hong-Rae Lee Pages: 101 - 116 Abstract: Publication date: October 2017 Source:Advances in Engineering Software, Volume 112 Author(s): Seung-Ho Ham, Myung-Il Roh, Hyewon Lee, Jin-Wuk Hong, Hong-Rae Lee The motions of the mega floating crane and the lifted module must be evaluated in advance, to determine whether they satisfy the safety criteria or not. Due to the limitations of the existing dynamic analysis programs, we develop a differentiated program that is dedicated to the mega floating crane. This program is focused on reducing modeling time, while increasing modeling accuracy. Furthermore, it can model the block loader that distributes the tension in wire ropes between the lifted module and the block loader equally, and link beams that are used to connect hooks by hinge joints. The equations of motion based on multibody system dynamics are derived. Wave, wind, and current are included as external environmental loads. A direct volume calculation method below the water plane is adopted to find the buoyant force and center of buoyancy. External loads are verified by commercial program. Finally, the simulation results of the module erection are validated by comparison with the measurement of real operation.
Authors:Hai Du; Muguo Li; Juan Meng Pages: 117 - 123 Abstract: Publication date: October 2017 Source:Advances in Engineering Software, Volume 112 Author(s): Hai Du, Muguo Li, Juan Meng Research on changes in the fluid edge of a wave flume is important for experimental hydrodynamics. However, disturbances often occur because of the presence of sensors. To solve this problem, a new grey-scale image processing method for fluid edge analysis is presented here. By fusing methods combining image gradients and image segmentation with shifting-window technology and with concepts derived from experimental fluid mechanics, the proposed method can overcome many of the inherent challenges of fluid-edge measurement. First, the geodesic distance is modified to obtain a class curve. Second, an edge position is determined by the inflection point of the class curve related to the gradient peak distribution. Next, the position of the interrogation window is relocated with reference to neighbors or to previous results, and the current edge position can be calculated according to the predicted value. During the computation, the interrogation window can change its position adaptively with fluid motion, ensuring that the amount of data to be analyzed always remains stable. A model combining the class curve and gradient curve can improve the validity of edge identification. Finally, the performance of the proposed method has been evaluated using images in a glass flume. The results show that the proposed method for studying the fluid edge is effective and robust.
Authors:Michal Merta; Lubomir Riha; Ondrej Meca; Alexandros Markopoulos; Tomas Brzobohaty; Tomas Kozubek; Vit Vondrak Pages: 124 - 135 Abstract: Publication date: October 2017 Source:Advances in Engineering Software, Volume 112 Author(s): Michal Merta, Lubomir Riha, Ondrej Meca, Alexandros Markopoulos, Tomas Brzobohaty, Tomas Kozubek, Vit Vondrak This paper describes an approach for acceleration of the Hybrid Total FETI (HTFETI) domain decomposition method using the Intel Xeon Phi coprocessors. The HTFETI method is a memory bound algorithm which uses sparse linear BLAS operations with irregular memory access pattern. The presented local Schur complement (LSC) method has regular memory access pattern, that allows the solver to fully utilize the Intel Xeon Phi fast memory bandwidth. This translates to speedup over 10.9 of the HTFETI iterative solver when solving 3 billion unknown heat transfer problem (3D Laplace equation) on almost 400 compute nodes. The comparison is between the CPU computation using sparse data structures (PARDISO sparse direct solver) and the LSC computation on Xeon Phi. In the case of the structural mechanics problem (3D linear elasticity) of size 1 billion DOFs the respective speedup is 3.4. The presented speedups are asymptotic and they are reached for problems requiring high number of iterations (e.g., ill-conditioned problems, transient problems, contact problems). For problems which can be solved with under hundred iterations the local Schur complement method is not optimal. For these cases we have implemented sparse matrix processing using PARDISO also for the Xeon Phi accelerators.
Authors:J. Calvo; J. Gracia; E. Bayo Pages: 136 - 146 Abstract: Publication date: October 2017 Source:Advances in Engineering Software, Volume 112 Author(s): J. Calvo, J. Gracia, E. Bayo Current trends in web application development favours bi-directional communication between front-end and back-end applications instead of the traditional ones where the front-end is constantly monitoring the back-end. This way of communication improves the user experience and this work tries to find the best bi-directional way of communication particularized to structural analysis software as a service or web applications. The effects of the most significant factors have been studied to optimize the total time involved in the communication, which is comprised of: time spent sending data from the client to the server, server data processing, and time consumed returning the data back. Design of experiments (DoE) techniques have been used to characterize the influence of four factors: serialization language, communication protocol, amount of data (size of the structure measured by the number of elements), and server post-processing. Moreover, factors like server workload and network congestion have also been addressed. The first factor is dealt with as a nuisance factor whose influence is to be minimized, and the second one as an uncontrollable variable.
Authors:Wenzhen Qu; Yaoming Zhang; Yan Gu; Fajie Wang Pages: 147 - 153 Abstract: Publication date: October 2017 Source:Advances in Engineering Software, Volume 112 Author(s): Wenzhen Qu, Yaoming Zhang, Yan Gu, Fajie Wang Thermal stress analysis is one of key aspects in mechanical design. Based on the indirect boundary integral equation (BIE) and the radial integration method (RIM), this paper develops a boundary-only element method for the boundary stress analysis of three-dimensional (3D) static thermoelastic problems. A transformation system constructed with the normal and two special tangential vectors is used to regularize the singularity in the indirect BIE. The RIM is then employed to transform the domain integrals arising in both displacement and its derivative integral equations into the equivalent boundary integrals, which results in a pure boundary discretized algorithm. Several numerical experiments are provided to verify the accuracy and convergence of the present approach.
Authors:Hanfeng Yin; Youye Xiao; Guilin Wen; Hongbing Fang Pages: 154 - 164 Abstract: Publication date: October 2017 Source:Advances in Engineering Software, Volume 112 Author(s): Hanfeng Yin, Youye Xiao, Guilin Wen, Hongbing Fang As one of the most widely used safety devices on highways, W-beam guardrail plays an important role in protecting errant vehicles from entering dangerous zones or colliding with oncoming vehicles. As one of the most widely used safety devices on highways, W-beam guardrails play an important role in protecting errant vehicles from entering dangerous zones or colliding with oncoming vehicles. One common issue with the traditional W-beam guardrails (TWG) is tire snagging which often occurred when the wheel of a striking vehicle entangled with a guardrail post. Tire snagging reduces the redirection performance of the guardrail and can result in serious injuries to the occupants. In this study, a new W-beam guardrail, named as “η-shaped W-beam guardrail (η-WG)”, was developed using nonlinear finite element simulations combined with metamodeling-based design optimization methodology. The simulation results showed that tire snagging did not occur on the η-WG and the optimum design of the η-WG had an improved safety performance in vehicular crashes.
Authors:Jelena Ninić; Christian Koch; Janosch Stascheit Pages: 165 - 179 Abstract: Publication date: October 2017 Source:Advances in Engineering Software, Volume 112 Author(s): Jelena Ninić, Christian Koch, Janosch Stascheit Building and construction information modelling for decision making during the life cycle of infrastructure projects are vital tools for the analysis of complex, integrated, multi-disciplinary systems. The traditional design process is cumbersome and involves significant manual, time-consuming preparation and analysis as well as significant computational resources. To ensure a seamless workflow during the design and analysis and to minimise the computation time, we propose a novel concept of multi-level numerical simulations, enabling the modelling on different Levels of Detail (LoDs) for each physical component, process information, and analysis type. In this paper, we present SATBIM, an integrated platform for information modelling, structural analysis and visualisation of the mechanised tunnelling process for design support. Based on a multi-level integrated parametric Tunnel Information Model, numerical models for each component on different LoDs are developed, considering proper geometric as well as material representation, interfaces and the representation of the construction process. Our fully automatic modeller for arbitrary tunnel alignments provides a high degree of automation for the generation, the setup and the execution of the simulation model, connecting the multi-level information model with the open-source simulation software KRATOS. The software of SATBIM is organized in a modular way in order to offer high flexibility not only for further extensions, but also for adaptation to future improvements of the simulation software. The SATBIM platform enables practical, yet flexible and user-friendly generation of the tunnel structure for arbitrary alignments on different LoDs, supporting the design process and providing an insight into soil-structure interactions during construction.
Authors:Giuseppe Bianchi; Sham Rane; Ahmed Kovacevic; Roberto Cipollone Pages: 180 - 191 Abstract: Publication date: October 2017 Source:Advances in Engineering Software, Volume 112 Author(s): Giuseppe Bianchi, Sham Rane, Ahmed Kovacevic, Roberto Cipollone The limiting factor for the employment of advanced 3D CFD tools in the analysis and design of rotary vane machines is the unavailability of methods for generation of a computational grid suitable for fast and reliable numerical analysis. The paper addresses this issue through an analytical grid generation based on the user defined nodal displacement which discretizes the moving and deforming fluid domain of the sliding vane machine and ensures conservation of intrinsic quantities by maintaining the cell connectivity and structure. Mesh boundaries are defined as parametric curves generated using trigonometrical modelling of the axial cross section of the machine while the distribution of computational nodes is performed using algebraic algorithms with transfinite interpolation, post orthogonalisation and smoothing. Algebraic control functions are introduced for distribution of nodes on the rotor and casing boundaries in order to achieve good grid quality in terms of cell size and expansion. For testing of generated grids, single phase simulations of an industrial air rotary vane compressor are solved by use of commercial CFD solvers FLUENT and CFX. This paper presents implementation of the mesh motion algorithm, stability and robustness experienced with the solvers when working with highly deforming grids and the obtained flow results.
Authors:Jianguang Fang; Na Qiu; Xiuzhe An; Fenfen Xiong; Guangyong Sun; Qing Li Pages: 192 - 199 Abstract: Publication date: October 2017 Source:Advances in Engineering Software, Volume 112 Author(s): Jianguang Fang, Na Qiu, Xiuzhe An, Fenfen Xiong, Guangyong Sun, Qing Li Hybrid structures with different materials have aroused increasing interest for their lightweight potential and excellent performances. This study explored the optimization design of steel–aluminum hybrid structures for the highly nonlinear impact scenario. A metamodel based multi-response objective-oriented sequential optimization was adopted, where Kriging models were updated with sequential training points. It was indicated that the sequential sampling strategy was able to obtain a much higher local accuracy in the neighborhood of the optimum and thus to yield a better optimum, although it did lead to a worse global accuracy over the entire design space. Furthermore, it was observed that the steel–aluminum hybrid structure was capable of decreasing the peak force and simultaneously enhancing the energy absorption, compared to the conventional mono-material structure.
Authors:Ge Yang; Bin Wu; Ge Ou; Zhen Wang; Shirley Dyke Pages: 200 - 210 Abstract: Publication date: October 2017 Source:Advances in Engineering Software, Volume 112 Author(s): Ge Yang, Bin Wu, Ge Ou, Zhen Wang, Shirley Dyke Hybrid simulation has been demonstrated to be a powerful method to evaluate the system-level dynamic performance of structure. With the numerical substructure analyzed with finite element software and the difficult-to-model components tested with an experimental substructure, complex structures with sophisticated behaviors can readily be examined through a hybrid simulation. To coordinate and synchronize the substructures in hybrid simulation, software is required. In recent studies, model updating has been integrated into hybrid simulation to improve testing accuracy by updating the numerical model during the analysis. However, online model updating scheme requires some modifications in the typical hybrid simulation testing procedure, and this greater complexity is entailed in its implementation regarding the collaboration of identification algorithms with existing hybrid simulation software. To address this issue and broaden the utilization of hybrid simulation with model updating, an existing platform named HyTest originally for conventional hybrid simulation is extended for this purpose. This version of HyTest facilitates the online identification of material constitutive parameters using experimental measurements in its finite element based identification module. It also includes a data center with a uniform data transmission protocol to incorporate different substructures and modules. A numerical example is used to demonstrate the online identification of material parameters for concrete and steel models in a reinforced column, and to verify the accuracy of the identification module. Lastly the effectiveness of HyTest in conducting hybrid simulation with model updating is validated using actual hybrid tests on a steel frame.
Authors:Yixian Du; Hanzhao Li; Zhen Luo; Qihua Tian Pages: 211 - 221 Abstract: Publication date: October 2017 Source:Advances in Engineering Software, Volume 112 Author(s): Yixian Du, Hanzhao Li, Zhen Luo, Qihua Tian To improve the poor shear performance of periodic lattice structure consisting of hexagonal unit cells, this study develops a new computational design method to apply topology optimization to search the best topological layout for lattice structures with enhanced shear stiffness. The design optimization problem of micro-cellular material is formulated based on the properties of macrostructure to maximize the shear modulus under a prescribed volume constraint using the energy-based homogenization method. The aim is to determine the optimal distribution of material phase within the periodic unit cell of lattice structure. The proposed energy-based homogenization procedure utilizes the sensitivity filter technique, especially, a modified optimal algorithm is proposed to evolve the microstructure of lattice materials with distinct topological boundaries. A high shear stiffness structure is obtained by solving the optimization model. Then, the mechanical equivalent properties are obtained and compared with those of the hexagonal honeycomb sandwich structure using a theoretical approach and the finite element method (FEM) according to the optimized structure. It demonstrates the effectiveness of the proposed method in this paper. Finally, the structure is manufactured, and then the properties are tested. Results show that the shear stiffness and bearing properties of the optimized lattice structure is better than that of the traditional honeycomb sandwich structure. In general, the proposed method can be effectively applied to the design of periodic lattice structures with high shear resistance and super bearing property.
Authors:Yu-Fen Cheng; Feng-Nan Hwang Pages: 222 - 230 Abstract: Publication date: October 2017 Source:Advances in Engineering Software, Volume 112 Author(s): Yu-Fen Cheng, Feng-Nan Hwang Many scientific and engineering applications require accurate, fast, robust, and scalable numerical solution of large sparse algebraic polynomial eigenvalue problems (PEVP’s) that arise from some appropriate discretization of partial differential equations. The polynomial Jacobi-Davidson (PJD) algorithm has been numerically shown as a promising approach for the PEVP’s to finding the interior spectrum. The PJD algorithm is a subspace method, which extracts the candidate eigenpair from a search space and the space updated by embedding the solution of the correction equation at the JD iteration. In this research, we develop and study the two-level PJD algorithm for PEVP’s with emphasis on the application of the dissipative acoustic cubic eigenvalue problem. The proposed two-level PJD algorithm consists of two important ingredients: A good initial basis for the search space is constructed on the fine-level by using the interpolation of the coarse solution of the same eigenvalue problem in order to enhance the robustness of the algorithm. Also, an efficient and scalable two-level preconditioner based on the Schwarz framework is used for the correction equation. Some numerical examples obtained on a parallel cluster of computers are given in order to demonstrate the robustness and scalability of our PJD algorithm.
Authors:Frédéric Magoulès; Mark Parsons; Lorna Smith Pages: 1 - 2 Abstract: Publication date: September 2017 Source:Advances in Engineering Software, Volume 111 Author(s): Frédéric Magoulès, Mark Parsons, Lorna Smith
Authors:Maria Elena Innocenti; Alec Johnson; Stefano Markidis; Jorge Amaya; Jan Deca; Vyacheslav Olshevsky; Giovanni Lapenta Pages: 3 - 17 Abstract: Publication date: September 2017 Source:Advances in Engineering Software, Volume 111 Author(s): Maria Elena Innocenti, Alec Johnson, Stefano Markidis, Jorge Amaya, Jan Deca, Vyacheslav Olshevsky, Giovanni Lapenta Space weather is a rapidly growing field of science which studies processes occurring in the area of space between the Sun and the Earth. The development of space weather forecasting capabilities is a task of great societal relevance: space weather effects may damage a number of technological assets, among which power and communication lines, transformers, pipelines and the telecommunication infrastructure. Exascale computing is a fundamental ingredient for space weather forecasting tools based on physical, rather than statistical, models. We describe here our recent progresses towards a physics-based space weather forecasting tool with exascale computing. We select the semi-implicit, Particle In Cell, Implicit Moment Method implemented in the parallel, object-oriented, C++ iPic3D code as a promising starting point. We analyze the structure and the performances of the current version of the iPic3D code. We describe three algorithmic developments, the fully implicit method, the Multi-Level Multi-Domain method, and the fluid-kinetic method, which can help addressing the multiple spatial and temporal scales present in space weather simulations. We then examine, in a co-design approach, which requirements – vectorization, extreme parallelism and reduced communication – an application has to satisfy to fully exploit architectures such as GPUs and Xeon Phi’s. We address how to modify the iPic3D code to better satisfy these requirements. We then describe how to port the iPic3D code to the DEEP architecture currently under construction. The FP7 project DEEP (www.deep-project.eu) aims at building an exascale-ready machine composed of a cluster of Xeon nodes and of a collection of Xeon Phi coprocessors, used as boosters. The aim of the DEEP project is to enable exascale performance for codes, such as iPic3D, composed of parts which exhibit different potential for extreme scalability. Finally, we provide examples of simulations of space weather processes done with the current version of the iPic3D code.
Authors:Nick Brown Pages: 18 - 25 Abstract: Publication date: September 2017 Source:Advances in Engineering Software, Volume 111 Author(s): Nick Brown Whilst there have been great advances in HPC hardware and software in recent years, the languages and models that we use to program these machines have remained much more static. This is not from a lack of effort, but instead by virtue of the fact that the foundation that many programming languages are built on is not sufficient for the level of expressivity required for parallel work. The result is an implicit trade-off between programmability and performance which is made worse due to the fact that, whilst many scientific users are experts within their own fields, they are not HPC experts. Type oriented programming looks to address this by encoding the complexity of a language via the type system. Most of the language functionality is contained within a loosely coupled type library that can be flexibly used to control many aspects such as parallelism. Due to the high level nature of this approach there is much information available during compilation which can be used for optimisation and, in the absence of type information, the compiler can apply sensible default options thus supporting both the expert programmer and novice alike. We demonstrate that, at no performance or scalability penalty when running on up to 8196 cores of a Cray XE6 system, codes written in this type oriented manner provide improved programmability. The programmer is able to write simple, implicit parallel, HPC code at a high level and then explicitly tune by adding additional type information if required.
Authors:Florin Isaila; Javier Garcia; Jesus Carretero; Rob Ross; Dries Kimpe Pages: 26 - 31 Abstract: Publication date: September 2017 Source:Advances in Engineering Software, Volume 111 Author(s): Florin Isaila, Javier Garcia, Jesus Carretero, Rob Ross, Dries Kimpe The ever-increasing data needs of scientific and engineering applications require novel approaches to managing and exploring huge amounts of information in order to advance scientific discovery. In order to achieve this goal, one of the main priorities of the international scientific community is addressing the challenges of performing scientific computing on exascale machines within the next decade. Exascale platforms likely will be characterized by a three to four orders of magnitude increase in concurrency, a substantially larger storage capacity, and a deepening of the storage hierarchy. The current development model of independently applying optimizations at each layer of the system I/O software stack will not scale to the new levels of concurrency, storage hierarchy, and capacity. In this article we discuss the current development model for the I/O software stack of high-performance computing platforms. We identify the challenges of improving scalability, performance, energy efficiency, and resilience of the I/O software stack, while accessing a deepening hierarchy of volatile and nonvolatile storage. We advocate for radical new approaches to reforming the I/O software stack in order to advance toward exascale.
Authors:Abal-Kassim Cheik Ahamed; Frédéric Magoulès Pages: 32 - 42 Abstract: Publication date: September 2017 Source:Advances in Engineering Software, Volume 111 Author(s): Abal-Kassim Cheik Ahamed, Frédéric Magoulès Performance computations depend on the machine architecture, the operating system, the problem studied and obviously on the programming implementation. Solving partial differential equations by numerical methods such as the finite element method requires the solution of large sparse linear systems. Graphics processing unit (GPU) is now commonly used to accelerate numerical simulations and most supercomputers provide large number of GPUs to their users. This paper proposes a comparison of both CUDA and OpenCL GPU languages to take the highest performance of multi-GPUs clusters. We analyse, evaluate and compare their respective performances for computing linear algebra operations and for solving large sparse linear systems with the conjugate gradient iterative method on multi-GPUs clusters.
Authors:Alexander S. Minkin; Andrey A. Knizhnik; Boris V. Potapkin Pages: 43 - 51 Abstract: Publication date: September 2017 Source:Advances in Engineering Software, Volume 111 Author(s): Alexander S. Minkin, Andrey A. Knizhnik, Boris V. Potapkin We study the efficiency of OpenCL implementations for Tersoff and embedded-atom interatomic potentials. We show that Tersoff potential can be computed faster using atomic operations rather than using longer kernel code. On the contrary better performance can be gained for embedded-atom potential without atomic operations. Numerical force computation algorithm is the slowest but shows the best scaling with the highest GPU acceleration. The GPU acceleration of different algorithms was evaluated and compared to the serial implementations of similar algorithms. The performance of GPU implementations is superior to their serial counterparts and depends on the algorithm and arithmetic precision. The corresponding benchmarks and performance comparison were done using NVidia GPUs and Intel CPUs.
Authors:T.A. Puurtinen; J.I. Toivanen; K. Mattila; J. Hyväluoma; R.W. Nash; P.V. Coveney; J. Timonen Pages: 52 - 57 Abstract: Publication date: September 2017 Source:Advances in Engineering Software, Volume 111 Author(s): T.A. Puurtinen, J.I. Toivanen, K. Mattila, J. Hyväluoma, R.W. Nash, P.V. Coveney, J. Timonen The MPI intercommunication framework was used for coupling of two lattice-Boltzmann solvers with suspended particles, which model advection and diffusion respectively of these particles in a carrier fluid. Simulation domain was divided into two parts, one with advection and diffusion, and the other with diffusion only (no macroscopic flow). Particles were exchanged between these domains at their common boundary by a direct process to process communication. By analysing weak and strong scaling, it was shown that the linear scaling characteristics of the lattice-Boltzmann solvers were not compromised by their coupling.
Abstract: Publication date: Available online 22 September 2017 Source:Advances in Engineering Software Author(s): Ji-Hyun Jung, Dae-Sung Bae This research proposes an implementation of effective direct linear equation solver for mechanical multi-body dynamics analysis. The proposed method focuses on the solvability for any size of GPU memory and scalability for any number of GPUs by using BFS-based traversal. A multi-level tree is divided into as many sub-trees as a GPU number by using the nested dissection, each of which is assigned to each GPU. Balanced graph bisection, additional sub-trees, and work stealing lead to minimum idle GPU computing time. Numerical experiments have been performed to decide the optimal maximum block size. Three mechanical models and the other three matrices from UF collection have been solved to show the effectiveness of the proposed method. Two different kinds of 4 GPUs, GeForce GTX 460 and GTX TITAN BLACK, are involved in this experiment. The proposed method shows a good solvability even when the test GPU memory is dozens of times smaller than the required data size for numerical factorization. The proposed optimization algorithm presents a good scalability on the number of GPUs. The performance results are compared with those obtained from CHOLMOD included in SuiteSparse library.
Abstract: Publication date: Available online 22 September 2017 Source:Advances in Engineering Software Author(s): Silvia Tolo, Edoardo Patelli, Michael Beer Bayesian Networks are a flexible and intuitive tool associated with a robust mathematical background. They have attracted increasing interest in a large variety of applications in different fields. In spite of this, inference in traditional Bayesian Networks is generally limited to only discrete variables or to probabilistic distributions (adopting approximate inference algorithms) that cannot fully capture the epistemic imprecision of the data available. In order to overcome these limitations, Credal Networks have been proposed to integrate Bayesian Networks with imprecise probabilities which, adopting non-probabilistic or hybrid models, allow to fully represent the information available and its uncertainty. Here, a novel computational tool, implemented in the general purpose software OpenCossan, is proposed. The tool provides the reduction of Credal Networks through the use of structural reliability methods, in order to limit the cost associated with the inference computation without impoverishing the quality of the information initially introduced. Novel algorithms for the inference computation of networks involving probability bounds are provided. In addition, a novel sensitivity approach is proposed and implemented into the Toolbox in order to identify the maximum tolerable uncertainty associated with the inputs.
Abstract: Publication date: Available online 21 September 2017 Source:Advances in Engineering Software Author(s): Zaher Mundher Yaseen, Ravinesh C. Deo, Ameer Hilal, Abbas M. Abd, Laura Cornejo Bueno, Sancho Salcedo-Sanz, Moncef L. Nehdi In this research, a machine learning model namely extreme learning machine (ELM) is proposed to predict the compressive strength of foamed concrete. The potential of the ELM model is validated in comparison with multivariate adaptive regression spline (MARS), M5 Tree models and support vector regression (SVR). The Lightweight foamed concrete is produced via creating a cellular structure in a cementitious matrix during the mixing process, and is widely used in heat insulation, sound attenuation, roofing, tunneling and geotechnical applications. Achieving product consistency and accurate predictability of its performance is key to the success of this technology. In the present study, an experimental database encompassing pertinent data retrieved from several previous studies has been created and utilized to train and validate the ELM, MARS, M5 Tree and SVR machine learning models. The input parameters for the predictive models include the cement content, oven dry density, water-to-binder ratio and foamed volume. The predictive accuracy of the four models has been assessed via several statistical score indicators. The results showed that the proposed ELM model achieved an adequate level of prediction accuracy, improving MARS, M5 Tree and SVR models. Hence, the ELM model could be employed as a reliable and accurate data intelligent approach for predicting the compressive strength of foamed concrete, saving laborious trial batches required to attain the desired product quality.
Authors:X.X. Li; W.D. Li; F.Z. He Abstract: Publication date: Available online 6 September 2017 Source:Advances in Engineering Software Author(s): X.X. Li, W.D. Li, F.Z. He NC programs are widely developed and applied to various machining processes. However, the lack of effective NC program optimization strategy for the machining energy efficiency has been crippling the implementation of sustainability in companies. To address this issue, a multi-granularity NC program optimization approach for energy efficient machining has been developed and presented in this paper. This approach consists of two levels of granularities: the granularity of a group of NC programs for a setup where the features are machined on a single CNC machine with the same fixture and the granularity of a NC program. On the former level of granularity, the execution sequence of the NC programs for the setup of a part is optimized to reduce the energy consumed by the cutting tool change among the NC programs. On the latter level of granularity, the execution sequence of the features in the same NC program is optimized to reduce the energy consumed by the cutting tool's traveling among the machining features. Experiments on the practical cases show that the optimization results from this approach are promising and the approach has significant potential of applicability in practice.
Authors:S. Castillo-Rivera; M. Tomas-Rodriguez Abstract: Publication date: Available online 5 September 2017 Source:Advances in Engineering Software Author(s): S. Castillo-Rivera, M. Tomas-Rodriguez This work presents a helicopter dynamic model that captures the fuselage vibrations for an accelerated main rotor. Some rotor parameters are modified with the purpose of study their impact on the rotorcraft. Being this, a tool that allows to predict vibrations on the helicopter. The rotorcraft model has been built up by using VehicleSim, software specialized in modelling mechanical systems composed by rigid bodies. The rotors are articulated, the main rotor takes into account flap, lag and feather degrees of freedom for each of the equispaced blades and their dynamic couplings. The dynamic performance and the control action are embedded in a single code, thereby VehicleSim does not require external connection to other software package. This generates some advantages such as to reduce the compilation time. The control methodology makes use of PID controllers (Proportional, Integral, Derivative), which allows to use VehicleSim commands exclusively. The state space matrices have been obtained in order to analysis the uncoupled main rotor flap and lag modes. The detection of vibrations from the offset flap hinge as well as the lag hinge are not straightforward tasks and this helicopter model provides an accurate tool to study these. A short time Fourier transform processing is used to analysis the vibrations and these have shown to agree with the expected behaviour.
Authors:Jie Xia; Hui Jin Abstract: Publication date: Available online 4 September 2017 Source:Advances in Engineering Software Author(s): Jie Xia, Hui Jin Welding is a significant joining technology in engineering construction. In addition to the effect of residual stress on joining quality, an obstacle in welding analysis is the complex phenomena, including phase transformation, thermal cycle and microstructure kinetics. The influence is manifested by microstructural development, defect formation and metallurgy transformation in the weld region. For the further knowledge of phase transformation behavior in the welding process, a simulation procedure of coupling thermo-metallurgical is elaborated by utilizing finite element theory. Heat transfer analysis and solid-state transformation in the welding process are implemented in the developed welding simulation model. The Koistinen–Marburger model and Leblond phase evaluation model are employed in the established user subroutine tool to consider the continuous heating transformation and continuous cooling transformation. The utilization of this method makes it possible to more precisely highlight the phase transformation behavior law in the welding region since the thermal cycle in welding process is essentially different from the general heat treatment process. The thermal cycle and cooling rate are taken into account to predict the metallurgical transformation behavior and phase fraction. Transformation latent heat is implemented in the proposed procedure for the thermal–metallurgical coupling analysis in welding. The calculated results are compared with some experimental data and results from standard software. The proposed coupling analysis simulation model is validated by the good agreement between the simulated and experimental results.
Authors:Dongquan Wu; Hongyang Jing; Lianyong Xu; Lei Zhao; Yongdian Han Abstract: Publication date: Available online 1 September 2017 Source:Advances in Engineering Software Author(s): Dongquan Wu, Hongyang Jing, Lianyong Xu, Lei Zhao, Yongdian Han The creep crack constraint effects using a load-independent creep constraint parameter Q* and the creep crack initiation (CCI) times were characterized by 3D finite element method for pipelines with circumferential surface cracks of different geometrical sizes. The results revealed that the distribution regulation of Q* along the crack front for circumferential internal surface cracks and external surface cracks was similar. The maximum constraint level occurred near the deepest crack front part for cracks with smaller a/c, while it occurred near the free surface for cracks with larger a/c. The constraint values at the same position (2Φ/π) increased with the increasing of the crack depth when a/c kept constant. The circumferential internal surface cracks of pipelines were proved more dangerous than the external surface cracks with the same geometrical size. Furthermore, the CCI times were decided by the peak values of constraint, or the CCI firstly occurred at the position where the constraint level was maximum. In addition, the empirical relationships between the CCI times and crack sizes were fitted, which was also verified effectively.
Authors:Guiwen Lan; Yuzhong Shen; Tianwei Chen; Hongwei Zhu Abstract: Publication date: Available online 24 August 2017 Source:Advances in Engineering Software Author(s): Guiwen Lan, Yuzhong Shen, Tianwei Chen, Hongwei Zhu Automatic assessment of image quality has become increasingly important in numerous applications that utilize digital images. This is usually accomplished with no-reference image quality assessment (NR-IQA) techniques that use structural similarity (SSIM) index as a quality indicator. NR-IQA is computationally intensive because it generally involves image convolution and other time-consuming computations. A typical SSIM-based NR-IQA includes four computational operations: color to grayscale conversion, Gaussian blur, computation of image gradients with an 8-direction Sobel operator, and computation of SSIM indices of local windows in the image. Parallel computing using multi-core CPUs or many-core GPUs is often used to accelerate intensive computational problems. This research presents the design of three parallel implementations of SSIM-based NR-IQA methods to accelerate the computations. The first two utilize NVIDIA CUDA to implement all the operations as CUDA kernels, while the third uses Microsoft's Parallel Patterns Library to calculate mean similarity indices of local windows in the image. Experimental results showed that significant speedup can be achieved against the sequential method using all three methods, but it is more practical to use texture memory to perform the last task (similarity computation) because of its substantial enhancement in performance and its ease of scheduling when processing multiple images.
Authors:Jisong Zhang; Haijiang Li; Yinghua Zhao; Guoqian Ren Abstract: Publication date: Available online 23 August 2017 Source:Advances in Engineering Software Author(s): Jisong Zhang, Haijiang Li, Yinghua Zhao, Guoqian Ren Early stage decision-making for structural design critically influences the overall cost and environmental performance of buildings and infrastructure. However, the current approach often fails to consider the multi-perspectives of structural design, such as safety, environmental issues and cost in a comprehensive way. This paper presents a holistic approach based on knowledge processing (ontology) to facilitate a smarter decision-making process for early design stage by informing designers of the environmental impact and cost along with safety considerations. The approach can give a reasoning based quantitative understanding of how the design alternatives using different concrete materials can affect the ultimate overall performance. Embodied CO2 and cost are both considered along with safety criteria as indicative multi-perspectives to demonstrate the novelty of the approach. A case study of a concrete structural frame is used to explain how the proposed method can be used by structural designers when taking multi performance criteria into account. The major contribution of the paper lies on the creation of a holistic knowledge base which links through different knowledge across sectors to enable the structural engineer to come up with much more comprehensive decisions instead of individual single objective targeted delivery.
Authors:Zhen-Zhong Hu; Pei-Long Tian; Sun-Wei Li; Jian-Ping Zhang Abstract: Publication date: Available online 21 August 2017 Source:Advances in Engineering Software Author(s): Zhen-Zhong Hu, Pei-Long Tian, Sun-Wei Li, Jian-Ping Zhang Incomplete building information in delivery and the lack of compatible tools for Operation and Maintenance (O & M) have hindered the development of the intelligent management of Mechanical, Electrical and Plumbing (MEP) systems. In fact, the information related to the O & M management of the MEP system conventionally comes from the completion documents in the forms of hard copies or unstructured digital files, making it hard to search for useful information in the “sea” of documents and drawings. Therefore, digitalization of information is an urgent task to facilitate the intelligent management of the MEP system. As a project deliverable, the as-built information model shall not only contain geometrical information and necessary construction-related data, but also built-in information useful for the intelligent O & M management. In the present study, based on the Building Information Modeling/Model (BIM) technology, a set of solutions including the automatic establishment of the logic chain for MEP systems, an equipment grouping and labeling scheme and an algorithm to transform BIM information to GIS map model, is proposed to digitalize and integrate the MEP-related information into the as-built model. Subsequently, a cross-platform O & M management system is developed using the MEP-related information in the as-built model to run routine O & M tasks and to effectively response to MEP-related emergencies. The developed system is applied to aid the O & M management of MEP engineering in a real project, showing that the developed system facilitates the intelligent O & M management and guarantees the security of the MEP system and its subsystems.
Authors:D. Dapelo; J. Bridgeman Abstract: Publication date: Available online 18 August 2017 Source:Advances in Engineering Software Author(s): D. Dapelo, J. Bridgeman For the first time, an Euler-Lagrange model for Computational Fluid Dynamics (CFD) is used to model a full-scale gas-mixed anaerobic digester. The design and operation parameters of a digester from a wastewater treatment works are modelled, and mixing is assessed through a novel, multi-facetted approach consisting of the simultaneous analysis of (i) velocity, shear rate and viscosity flow patterns, (ii) domain characterization following the average shear rate value, and (iii) concentration of a non-diffusive scalar tracer. The influence of sludge’s non-Newtonian behaviour on flow patterns and its consequential impact on mixing quality were discussed for the first time. Recommendations to enhance mixing effectiveness are given: (i) a lower gas mixing input power can be used in the digester modelled within this work without a significant change in mixing quality, and (ii) biogas injection should be periodically switched between different nozzle series placed at different distances from the centre.
Authors:Henrique M. Kroetz; Rodolfo K. Tessari; André T. Beck Abstract: Publication date: Available online 18 August 2017 Source:Advances in Engineering Software Author(s): Henrique M. Kroetz, Rodolfo K. Tessari, André T. Beck Solution of structural reliability and uncertainty propagation problems can be a computationally intensive task, since complex mechanical models have to be solved thousands or millions of times. In this context, surrogate models can be employed in order to reduce the computational burden. This article compares the performance of three global surrogate modeling techniques in the solution of structural reliability problems. The paper addresses artificial neural networks, polynomial chaos expansions and Kriging metamodeling. Analytical and numerical problems of increasingly complexity are addressed, including an eight-hundred bar, 3D steel lattice tower. Implementation strategies concerning data mapping and optimization of Kriging hyper parameters are proposed and discussed. Advantages and limitations of each technique are addressed. Results show that the three techniques explored herein are reliable tools for approximating the response of complex mechanical models.
Authors:Yong Jie Zhao; Yun Hui Yan; Ke Chen Song; Hao Nan Li Abstract: Publication date: Available online 17 August 2017 Source:Advances in Engineering Software Author(s): Yong Jie Zhao, Yun Hui Yan, Ke Chen Song, Hao Nan Li Grinding process of optical glass has been reported to be related with the creation of subsurface cracks. However, for the time being, most measurement methods have been depended on human operations. In this paper, an intelligent assessment method based on image processing technique is proposed. Grinding trials proved that, the proposed method can accurately (with the biggest relative error of 3.53%) and quickly (nearly 1.6 seconds per micrographs) recognize and measure the subsurface crack depths. More importantly, the proposed method has good robustness to different-sized images. Besides, the method does not require any input parameters or any adjustment of thresholds, therefore the method does not require any prior knowledge of either mechanical grinding process or brittle material behaviors relating with subsurface cracks. Based on above, the proposed method is expected to be meaningful to both metrology equipment companies and optical glass manufacturers.
Authors:Junchen Jin; Xiaoliang Ma; Iisakki Kosonen Abstract: Publication date: Available online 14 August 2017 Source:Advances in Engineering Software Author(s): Junchen Jin, Xiaoliang Ma, Iisakki Kosonen Traffic flow is considered as a stochastic process in road traffic modeling. Computer simulation is a widely used tool to represent traffic system in engineering applications. The increased traffic congestion in urban areas and their impacts require more efficient controls and management. While the effectiveness of control schemes highly depends on accurate traffic model and appropriate control settings, optimization techniques play a central role for determining the control parameters in traffic planning and management applications. However, there is still a lack of research effort on the scientific computing framework for optimizing traffic control and operations and facilitating real planning and management applications. To this end, the present study proposes a model-based optimization framework to integrate essential components for solving road traffic control problems in general. In particular, the framework is based on traffic simulation models, while the solution needs extensive computation during the engineering optimization process. In this work, an advanced genetic algorithm, extended by an external archive for storing globally elite genes, governs the computing framework, and in application it is further enhanced by a sampling approach for initial population and utilizations of adaptive crossover and mutation probabilities. The final algorithm shows superior performance than the ordinary genetic algorithm because of the reduced number of fitness function evaluations in engineering applications. To evaluate the optimization algorithm and validate the whole software framework, this paper illustrates a detailed application for optimization of traffic light controls. The study optimizes a simple road network of two intersections in Stockholm to demonstrate the model-based optimization processes as well as to evaluate the presented algorithm and software performance.
Authors:Pu Li; Haiyan Li; Yunbao Huang; Kefeng Wang; Nan Xia Abstract: Publication date: Available online 14 August 2017 Source:Advances in Engineering Software Author(s): Pu Li, Haiyan Li, Yunbao Huang, Kefeng Wang, Nan Xia Response surface method is often employed in simulation based design and optimization for complex products. The sparsity of response surface on the mathematic basis has been explored to accurately represent the variation between design variables and performance response with only a few design points, which is very beneficial to efficient design optimization. Due to the selected basis, it may lead to a large deviation, or under-fitting of the reconstructed response surface since the number of sampling points is often smaller than its sparseness. In this paper, a quasi-sparse response surface is presented to trade-off the sparsity and variation of response surface by introducing coefficient shrinkage regularization and uniformly sampling for the design points, which enables more atoms in the basis included to accurately and robustly reconstruct the surface. The group of basis atoms which are correlated with sampling points instead of the most correlated one are all selected to uniform express the sampling points, and the coefficients of basis atoms are shrunk to improve the prediction performance of the model. Finally, 9 benchmark functions and 1 engineering applications are utilized to demonstrate the significance of the presented approach by comparing with other normally used response surface models, The results shows that the accuracy and robustness of the reconstructed response surface is superior than those of other response surface approaches.
Authors:I. Jbira; M. Tlija; B. Louhichi; A. Tahan Abstract: Publication date: Available online 12 August 2017 Source:Advances in Engineering Software Author(s): I. Jbira, M. Tlija, B. Louhichi, A. Tahan Geometric deviations affect the assemblability and functional compliance of products, since small part variations accumulate through large-scale assemblies and lead to malfunctions. The Digital Muck Up (DMU) upgrade requires a tolerance consideration in CAD models. The improvement of tolerancing leads to industrial success. Therefore, improving the CAD model to be closer to the realistic model is a necessity to verify and validate the mechanical system assemblability. In previous work, an approach to consider the dimensional, positional and orientation tolerances in CAD models was developed. In this paper, the above approach is improved to take into account form defects in CAD models. To model the component with form defects, the toleranced face is modeled by gird vertices. According to form tolerance values, a White Gaussian Noise (WGN) of gird vertices is computed. The realistic face is obtained by an interpolation based on the tessellation using Thin Plate Surface (TPS) modeling. The realistic assembly configurations were performed by updating the mating constraints. In fact, in realistic modeling, a new method to redefine constraints, while respecting the Objective Function of the Assembly (OFA), is established. In the case of a planar joint, a sub-algorithm based on Oriented Bounding Box (OBB) and the matrix transformation is developed. Relative part displacements are simulated with or without guaranteeing contact. Tolerance impacts on the realistic assembly motion are quantified. The realistic cylindrical joint is performed using an optimization method: the minimum cylinder inside a realistic hole and the maximum cylinder outside a realistic pin. Finally, in the case of a revolute joint, a sub-algorithm to redefine the mating constraints between two realistic parts is performed. This paper proposes a new approach to incorporate tolerances on CAD models in the case of planar and cylindrical faces by determining configurations with positional, orientation and form defects. This approach provides an assembly result closer to the real assembly of the mechanical system. Integrating tolerances in CAD allows the simulation and visualization of the mechanical assemblies’ behavior in their real configurations.
Authors:Fabio M. Santiciolli; Riccardo Möller; Ivo Krause; Franco G. Dedini Abstract: Publication date: Available online 12 August 2017 Source:Advances in Engineering Software Author(s): Fabio M. Santiciolli, Riccardo Möller, Ivo Krause, Franco G. Dedini This paper presents a new approach to the virtualization of the scenario of the biaxial wheel fatigue test. This test is the state-of-art and the standard requirement for the validation of vehicle wheels. During this test, tire and wheel specimens run inside an inner drum while standardized vertical and horizontal loads are applied. Thus, the scenario of this test can be modeled in three levels: the multibody dynamics of the test facility, the wheel/tire/inner drum contact, and the analysis of the flexible wheel. In the proposed virtualization, the multibody dynamics of the test facility was implemented in MSC.ADAMS. The wheel/tire/inner drum contact was simulated by means of CDTire; as it works parallel to MSC.ADAMS, one single co-simulation could perform the tire dynamics and the test facility dynamics. Finally, the wheel strains were calculated by an ABAQUS simulation, which received the tire/wheel load data from the simulation in MSC.ADAMS and CDTire. A physical test facility and a physical wheel specimen were instrumented, allowing the comparison between acquired and simulated data. The use of this specialized software is a novelty in the virtualization of the scenario of this test; furthermore a high detailed simulation is required for the further development of such already well established test procedure.
Authors:Lijun Li; Yiran Liu; Fan Zhang; Zhenyong Sun Abstract: Publication date: Available online 12 August 2017 Source:Advances in Engineering Software Author(s): Lijun Li, Yiran Liu, Fan Zhang, Zhenyong Sun Helmholtz resonator is one of the most basic acoustic models in acoustic theoretical research and engineering applications. It is simple and effective to directly apply the theoretical formula for its resonant frequency calculation, but sometimes the calculation error is too large or even wrong. In this paper, the characteristics of Helmholtz resonators are studied based on the finite element numerical analysis. The influence of structural parameters and boundary conditions of the Helmholtz resonator on the resonant frequency is given, several related problems of the theoretical formula are supplemented and the relevant conclusions are obtained. The explanations employed in this paper could be used as a supplement to the theoretical formula for theoretical study and engineering applications of Helmholtz resonators.
Authors:A.B. Monteiro; A.R.V. Wolenski; F.B. Barros; R.L.S. Pitangueira; S.S. Penna Abstract: Publication date: Available online 12 August 2017 Source:Advances in Engineering Software Author(s): A.B. Monteiro, A.R.V. Wolenski, F.B. Barros, R.L.S. Pitangueira, S.S. Penna The Generalized/eXtended Finite Element Method (G/XFEM) has been developed with the purpose of overcoming some limitations inherent to the Finite Element Method (FEM). Different kinds of functions can be used to enrich the original FEM approximation, building a solution specially tailored to problem. Certain obstacles related to the nonlinear analysis can be mitigated with the use of such strategy and the damage and plasticity fronts can be precisely represented. A FEM computational environment has been previously enclosed the G/XFEM formulation to linear analysis with minimum impact in the code structure and with requirements for extensibility and robustness. An expansion of the G/XFEM implementation to physically nonlinear analysis under the approach of an Unified Framework for constitutive models based on elastic degradation is firstly presented here. The flexibility of the proposed framework is illustrated by several examples with different constitutive models, enrichment functions and analysis models.
Authors:Vijay Kumar; Dinesh Kumar Abstract: Publication date: Available online 22 May 2017 Source:Advances in Engineering Software Author(s): Vijay Kumar, Dinesh Kumar In this paper, modified schemes are proposed for preventing a grey wolf optimizer (GWO) from premature exploration and convergence on optimization problems. Three novel strategies are developed to improve the performance of existing GWO. The first strategy uses the concept of prey weight. The second strategy uses the astrophysics concepts, which guide the grey wolves toward more promising areas of the search space. The beauty of this strategy is to let each grey wolf learn from not only movement of sun (symbolizes prey) in the search space but also the wolves are made to explore and exploit simultaneously. Third strategy combines the both, first and second strategies to take advantages of prey weight and astrophysics strategies. The proposed improvements in GWO have been evaluated on thirteen benchmark test functions. The performance of the proposed modifications has been compared with other five recently developed state-of-the-art techniques. The effects of scalability, noise, and control parameter have also been investigated. The statistical tests have been performed to validate the significance of modified variants. The proposed variants are also applied for seven well-known constrained engineering design problems. The experimental results depict the supremacy of the proposed modified algorithm in solving engineering design problems when compared with several existing techniques.
Authors:Wen-Zheng Xu; Chun Bao Li; Joonmo Choung; Jae-Myung Lee Abstract: Publication date: Available online 22 May 2017 Source:Advances in Engineering Software Author(s): Wen-Zheng Xu, Chun Bao Li, Joonmo Choung, Jae-Myung Lee Corrosion defects occur very often on the internal and external surfaces of pipelines, which may result in a serious threat to the integrity of the pipelines. Numerous studies investigated failure behavior of corroded pipelines with single corrosion defects. However, few studies focus on interacting corrosion defects. Interacting defects are defined as defects with certain proximity that interact to reduce the overall strength of a pipeline. In the present study, the failure behavior of pipelines with interacting corrosion defects was studied using a finite element method, and then a solution was proposed to predict burst pressure using an artificial neural network. The solution was validated by experimental results in previous studies and compared with other existing assessment solutions to prove its applicability and efficiency.
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