Authors:Riadh Ben Hadj; Imen Belhadj; Moez Trigui; Nizar Aifaoui Pages: 1 - 11 Abstract: Publication date: May 2018 Source:Advances in Engineering Software, Volume 119 Author(s): Riadh Ben Hadj, Imen Belhadj, Moez Trigui, Nizar Aifaoui The automatic generation of the assembly/disassembly plan is considered a topical problem in the computer-aided tools area. The main problem of the major proposed approaches is the excessive processing time to treat the whole assembly model. This paper proposes a simplification approach of CAD models to make the generation of assembly plan easy. The developed method begins by the elimination of connection elements to obtain a simplified assembly sequence. A case-based reasoning algorithm is, then, developed to insert the entire eliminated elements in the global assembly sequence plan. Two examples of CAD assembly are treated in order to compare and validate the obtained results.
Authors:Xiaoxin Zhao; Lianyong Xu; Hongyang Jing; Lei Zhao; Jiangzhong Huang Pages: 12 - 20 Abstract: Publication date: May 2018 Source:Advances in Engineering Software, Volume 119 Author(s): Xiaoxin Zhao, Lianyong Xu, Hongyang Jing, Lei Zhao, Jiangzhong Huang The reel-lay approach is widely applied in submarine pipelines. During the process of reeling and unreeling, pipelines are subjected to nominal strain of 1–4%. In this study, various pipeline geometries and crack dimensions were calculated using a finite element analysis and analytical solution under strain-controlled boundary conditions. A modified reference stress approach was applied under strain-controlled boundary conditions using a derived implicit analytical solution of the nominal stress. The limit load solution was modified through a γ factor based on the finite element analysis under strain-controlled boundary conditions. A regression analysis of γ was conducted and an empirical formula was determined. The modified strain-controlled reference approach is in contrast to other ECA methods and proved to be closer to the finite element analysis results.
Authors:Jiyu Sun; Yueming Wang; Yunhai Ma; Jin Tong; Zhijun Zhang Pages: 30 - 37 Abstract: Publication date: May 2018 Source:Advances in Engineering Software, Volume 119 Author(s): Jiyu Sun, Yueming Wang, Yunhai Ma, Jin Tong, Zhijun Zhang Successive years of mechanical operations and conservation tillage in Northeast China have made subsoiling necessary, and the tillage depth can be no less than 40 cm. In this paper, a bionic design method was used to reduce subsoiler energy consumption and soil disturbance. The bionic structural elements, i.e., triangular prism (BTP) and partial circular column (BPCC), were inspired by the placoid scale rib structure of shark skin, which has low drag. These elements were then applied to the subsoiler to reduce energy consumption. Six types of bionic subsoilers were designed. Discrete element modeling (DEM) was used to simulate and analyze the interactions of the bionic subsoilers and an ordinary subsoiler (O-S) with the soil. The results showed that bionic subsoilers with a shank and BTP in the horizontal direction of motion (S-T-H) and tines with the BTP parallel to the centerline (T-T) had lower draft requirements and energy consumption than the other designs. The draft requirements and energy consumption of S-T-H subsoilers with different height-to-lateral-rib-spacing (h/s) ratios were then compared. The subsoiler with a bionic element h/s of 0.57 (S-T-H-0.57) had a lower draft requirement (1292.59 N) and a lower total energy requirement (23.48 J) than the other designs. A soil disturbance analysis demonstrated that S-T-H-0.57-T-T (bionic elements arranged in both the shank and tine) provided superior benefits in terms of root growth and improved crop stress resistance. The result is consistent with the mechanical analysis of the riblet, which will be helpful for designing new subsoilers with reduced drag and soil disturbance.
Authors:Shuaishuai Han; Haoping Wang; Yang Tian Pages: 38 - 47 Abstract: Publication date: May 2018 Source:Advances in Engineering Software, Volume 119 Author(s): Shuaishuai Han, Haoping Wang, Yang Tian The design of a 12 DOF lower limb multi-functional exoskeleton is realized in SolidWorks with the analysis of kinematics. For controller design, this paper presents the model-free based adaptive nonsingular fast terminal sliding mode control which comprises three parts: the intelligent PI controller, time-delay estimation, and adaptive sliding mode compensator. The proposed control strategy drives tracking errors to a nonsingular fast terminal sliding surface and realizes fast convergence in finite time. The designed adaptive law approximates the upper bound of estimation error in time-delay estimation and thus it reduces the fundamental chattering on the switching manifold. The stability of controller is verified by using Lyapunov theory. To validate the proposed method, the virtual prototype is transferred to MATLAB/SimMechanics as a platform for co-simulation. The proposed method shows improved tracking performance compared with the existing model free controller in co-simulations.
Authors:Aye Aye Maw; Tun Lwin; Maxim Tyan; Jae-Woo Lee; Sangho Kim Pages: 27 - 34 Abstract: Publication date: April 2018 Source:Advances in Engineering Software, Volume 118 Author(s): Aye Aye Maw, Tun Lwin, Maxim Tyan, Jae-Woo Lee, Sangho Kim The integration of distributed data sources is one of the main problems of engineering software. The data integration process for a heterogeneous legacy system is a key aspect of the development of a computerized system and in the integration of a design framework. In this research, our approach to data integration focuses on developing system-building techniques for efficient data integration queries. Keyword-based data searching is investigated and applied within a database for a design framework. A database table connector (DTC) wrapper program is implemented based on the use of data integration processes and keyword-based searching. The DTC provides data integration for various data resources from legacy programs and database management systems using SQL querying. The DTC enables designers and developers to rapidly and efficiently develop integration frameworks for different data resources. This paper also describes the implementation and deployment of the Certification and Aircraft Design Integration System framework, which integrates various analysis and optimization codes, computer-aided design software and database management systems. Multiple data types are used within the framework, including databases, spreadsheets, flat files, XML files and personal data management. Several aircraft design and optimization problems are successfully solved using the developed framework.
Authors:Štěpán Beneš; Jaroslav Kruis Pages: 8 - 17 Abstract: Publication date: March 2018 Source:Advances in Engineering Software, Volume 117 Author(s): Štěpán Beneš, Jaroslav Kruis A complex finite element analysis can produce large amount of data that is problematic to post-process in reasonable time. This paper describes application of Singular Value Decomposition (SVD) to the compression of results from finite element solvers. Although the idea of image compression method is an inspiration for this research work, the SVD compression algorithm used for compression of images cannot be directly used for FEM results. Differences and implementation challenges are discussed in the text. Quality of approximation is more important in scientific field than in computer graphics where the most significant factor is the human perception of the resulting image. Error estimation methods used during compression of finite element results are presented. The focus is also on the algorithm performance. SVD is a very computational intensive method. Therefore, various optimization techniques were investigated, e.g. randomized SVD. The method leads to the lower memory consumption, 10% of the original size or less, with negligible compression error.
Authors:Xianping Du; Feng Zhu Pages: 18 - 28 Abstract: Publication date: March 2018 Source:Advances in Engineering Software, Volume 117 Author(s): Xianping Du, Feng Zhu Complicated engineering products such as cars with a large number of components can be regarded as big data systems, where the vast amount of dependent and independent design variables must be considered systematically during the product development. To design such a system with high-dimensional design variables, this study aims at developing a novel methodology based on data mining theory, and it is implemented through designing a crashworthy passenger car, which is a multi-level (system – components) complicated system. Decision tree technique was used to mine the crash simulation datasets to identify the key design variables with most significant effect on the vehicular energy absorption response and determine the range of their values. In this way, the design space can be significantly reduced and the high-dimensional design problem is greatly simplified. The results suggest that the data mining based approach can be used to design a complicated structure with multiple parameters effectively and efficiently. Compared with the traditional design method, the new approach could simplify and speed up the design process without significant influence on the accuracy.
Authors:J.A. Romero; A.A. Lozano-Guzmán; S.A. Obregón-Biosca; E. Betanzo-Quezada Pages: 46 - 58 Abstract: Publication date: March 2018 Source:Advances in Engineering Software, Volume 117 Author(s): J.A. Romero, A.A. Lozano-Guzmán, S.A. Obregón-Biosca, E. Betanzo-Quezada In road transportation, bridges´ deck exhibit large deflections when compared with those of the pavements. The interaction of vehicles with these two types of road infrastructures signifies enormous costs for maintaining the whole infrastructure in economic operational conditions. In this paper, an integrated model for simulating the vehicle – infrastructure coupled interaction, is proposed. While the infrastructure model is based upon FEM, the vehicle considers a multibody model. A parametric analysis is carried out to analyse the effect of vehicle and infrastructure operational conditions, as well as vehicle design characteristics, on bridge and flexible pavement dynamic responses.
Authors:Martin Krejsa; Jiri Brozovsky; David Mikolasek; Premysl Parenica; Jakub Flodr; Alois Materna; Radim Halama; Jaroslav Kozak Pages: 59 - 69 Abstract: Publication date: March 2018 Source:Advances in Engineering Software, Volume 117 Author(s): Martin Krejsa, Jiri Brozovsky, David Mikolasek, Premysl Parenica, Jakub Flodr, Alois Materna, Radim Halama, Jaroslav Kozak The paper is focused on the numerical modeling of steel bearing elements and their verification using experiment. Currently, for the stress-strain analysis of the elements supporting structures it is possible to use many commercial software systems, based on the finite element method - FEM. It is important to to check and compare the results of FEM analysis with the results of physical verification test, in which the real behavior of the bearing element can be observed. The results of the comparison can be used for calibration of the computational model.The article deals with the physical test of steel supporting elements, whose main purpose is obtaining of material, geometry and strength characteristics of the fillet welds. The main aim was defining of tested samples numerical models for using FEM analysis and for the commercial software ANSYS. The pressure test was performed during the experiment, wherein the total load value and the corresponding deformation of the specimens under the load was monitored. The measurements were carried out for a more detailed analysis of stresses and deformations in welds samples using a strain-gauge and a Q100 laser device for measuring the 3D deformation and infrared thermographic non-destructive testing.Obtained data were used for the calibration of numerical models of test samples and they are necessary for further strain analysis of steel supporting elements.
Authors:João Rogeiro; Marta Rodrigues; Alberto Azevedo; Anabela Oliveira; João Paulo Martins; Mário David; João Pina; Nuno Dias; Jorge Gomes Pages: 70 - 79 Abstract: Publication date: March 2018 Source:Advances in Engineering Software, Volume 117 Author(s): João Rogeiro, Marta Rodrigues, Alberto Azevedo, Anabela Oliveira, João Paulo Martins, Mário David, João Pina, Nuno Dias, Jorge Gomes Computational forecast systems (CFS) are essential modelling tools for coastal management by providing water dynamics predictions. Nowadays CFS are processed in dedicated workstations, fulfilling quality control through automatic comparison with field data. Recently, CFS has been successfully ported to High Performance Computing (HPC) resources, maintained by highly-specialized staff in these complex environments. The need to increase the available resources for more demanding applications and to enhance the portability for use in non-scientific institutions has promoted the search for more flexible and user-friendly approaches. The scalability and flexibility of cloud resources, with dedicated services for facilitating their use, makes them an attractive option. Herein, the performance of CFS using ECO-SELFE MPI-based model is assessed and compared for the first time in multiple environments, including local workstations, an HPC cluster and a pilot cloud. The analysis is conducted in a range of resources from the physical core count available at the smaller resources to the optimal number of processes, using cloud and HPC cluster resources. Results for the smaller, common physical resources show that the cloud is an attractive option for CFS operation. As the optimal number of processes for the use case is at the limit of the workstations common pool, an analysis was also performed using HPC cluster nodes and federated MPI resources. Results show that the cloud remains an attractive option for CFS. This conclusion is valid both for the use of a single host or through federated hosts, providing that efficient communication infrastructure (such as SRIOV) is available.
Authors:Lamia Ait L'Hadj; Hocine Hammoum; Karima Bouzelha Pages: 80 - 88 Abstract: Publication date: March 2018 Source:Advances in Engineering Software, Volume 117 Author(s): Lamia Ait L'Hadj, Hocine Hammoum, Karima Bouzelha This work presents a methodology for assessing the damage level of an existing structure under seismic action. First, the seismic demand is introduced by the response spectrum provided by the seismic code, and then the nonlinear static equivalent analysis is performed by structural finite element software to obtain the capacity curve. The evaluated performance point according to the pushover analysis is positioned in European macroseismic scale in order to deduce the damage domain of the structure. The effectiveness of this proposed method is tested successfully for a real case. As a practical application, we analyse a highly complex structure which is an apartment building in Algiers surmounted by a reinforced concrete water tank with a container capacity of 1000 m3. It is complex in its design and analysis, and complex also by its behaviour under earthquake effect. Since being commissioned in 1962, this structure has been subjected to several earthquakes, but the one that hit Boumerdes town on 2003, was fatal for it. The proposed approach classifies the studied structure in the third domain; which describes a very important state of damage. This work fits into a practical environment of the engineering by combining analysis software with design codes and by the applicative character of the proposed approach.
Authors:S.K. Sharan Pages: 89 - 94 Abstract: Publication date: March 2018 Source:Advances in Engineering Software, Volume 117 Author(s): S.K. Sharan Linearization of a nonlinear failure criterion may be required if a software incorporating the nonlinear failure criterion is not readily available or if an additional computational difficulty is encountered due to the nonlinearity of the failure criterion. In this paper, a novel method is proposed for the linearization of nonlinear failure criteria. The proposed method is based on an iterative procedure and the least-squares regression is used for the linearization. The material is assumed to be elastic-perfectly plastic. By conducting analytical and finite element analyses of stresses and displacements around underground openings in rock mass governed by the generalized Hoek–Brown failure criterion, it is shown that the proposed method is convergent, efficient and effective.
Authors:W. Graf; M. Götz; M. Kaliske Pages: 95 - 106 Abstract: Publication date: March 2018 Source:Advances in Engineering Software, Volume 117 Author(s): W. Graf, M. Götz, M. Kaliske The design of structures is one of the major tasks for engineers. The objectives of numerical design – computing robust and reliable structures – can be realized by means of analyzing different variants, application of optimization tasks, or solving inverse problems. The method of choice depends on the objective of design, the problem and available data/resources. This contribution introduces an application oriented procedure for the solution of an inverse problem, on the basis of existing data. This data consists of design vectors and related responses. This contribution is focused on functional responses. With this procedure independent areas of permissible designs can identified. These areas are approximatively described by hyperrectangles, which are multi-dimensional boxes. The procedure uses various algorithms within the context of data mining. The relevant methods will be discussed shortly. The proposed field of application is the detection permissible design spaces in early design stages. Therefore the applicability of the presented procedure is shown by practical numerical design studies.
Authors:H. Nasser; A. Chabot Pages: 107 - 122 Abstract: Publication date: March 2018 Source:Advances in Engineering Software, Volume 117 Author(s): H. Nasser, A. Chabot This paper presents a half-analytical elastic solution convenient for parametric studies of 2D cracked pavements. The pavement structure is reduced to three elastic and homogeneous equivalent layers resting on a soil. In a similar way than the Pasternak's modelling for concrete pavements, the soil is modelled by one layer, named shear layer, connected to Winkler's springs in order to ensure the transfer of shear stresses between the pavement structure and the springs. The whole four-layer system is modelled using a specific model developed for the analysis of delamination in composite materials. It reduces the problem by one dimension and gives access to regular interface stresses between layers at the edge of vertical cracks allowing the initial debonding analysis. In 2D plane strain conditions, a system of twelve-second order differential equations is written analytically. This system is solved numerically by the finite difference method (Newmark) computed in the free Scilab software.The calculus tool allows analysis of the impact of material characteristics changing, loads and locations of cracks in pavements on the distribution of mechanical fields. The approach with fracture mechanic concepts is well suited for practical use and for some subsequent numerical developments in 3D.
Authors:D. Dapelo; J. Bridgeman Pages: 153 - 169 Abstract: Publication date: March 2018 Source:Advances in Engineering Software, Volume 117 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:Slowik Abstract: Publication date: March 2018 Source:Advances in Engineering Software, Volume 117 Author(s): D. Lehký, O. Slowik, D. Novák Two advanced optimization approaches to solving a reliability-based design problem are presented. The first approach is based on the utilization of an artificial neural network and a small-sample simulation technique. The second approach considers an inverse reliability task as a reliability-based optimization task using a double-loop optimization method based on small-sample simulation. Both techniques utilize Latin hypercube sampling with correlation control. The efficiency of both approaches is tested using three numerical examples of structural design – a cantilever beam, a reinforced concrete slab and a post-tensioned composite bridge. The advantages and disadvantages of the approaches are discussed.
Authors:D.D. Abstract: Publication date: March 2018 Source:Advances in Engineering Software, Volume 117 Author(s): D.D. Milašinović, D. Majstorović, R. Vukomanović A study on how a mathematical material modeling approach named rheological-dynamical analogy (RDA) can be used to predict the quasi static and dynamic inelastic buckling and failure of structures is presented in this paper. An analysis of the uniformly compressed folded-plate structures, made of isotropic materials, is carried out. Two sources of non-linearity, one involving geometrical non-linearity due to large deflection, and the other involving material non-linearity due to inelastic behavior, are analyzed by implementing a full-energy finite strip method (FSM). The material non-linearity is analyzed using the RDA. A very basic continuum damage model with one damage parameter is implemented in conjunction with a mathematical material modeling approach in order to address stiffness reduction due to inelastic behavior. According to the analogy, a very complicated material non-linear problem in the inelastic range of strains is solved as a simple linear dynamic one. The orthotropic constitutive relations are derived and modulus iterative method for the solution of nonlinear equations is presented.
Authors:Frédéric Magoulès; Guillaume Gbikpi-Benissan Abstract: Publication date: Available online 13 February 2018 Source:Advances in Engineering Software Author(s): Frédéric Magoulès, Guillaume Gbikpi-Benissan In this paper, we address the design of a communication library which particularly targets distributed iterative computing, including randomly executed asynchronous iterations. The well-known MPI programming framework is considered, upon which unique generic routines are proposed for both blocking and non-blocking communication modes. This allows for developing unique software applications to experiment both classical and asynchronous iterative methods through the same programming pattern. Convergence detection issues are investigated on pure algorithmic aspects, from which we provide an efficient exact approach to compute global convergence residual norms, by means of non-blocking synchronization. Point-to-point message reception and sending requests are carefully handled in view of producing the least possible delays about transmitted iterative data. Extensive experiments with an existing MPI-based scientific application validate both the proposed MPI-like programming framework and design options to achieve best performances of asynchronous iterative computing.
Abstract: Publication date: April 2018 Source:Advances in Engineering Software, Volume 118 Author(s): F. Pérez-Arribas, R. Pérez-Fernández This work presents a new design methodology for modelling the blades of propellers using B-spline surfaces. Propeller blades are good examples of free form surfaces, designed specifically considering several parameters that control their performance. Traditional tools for surface design in CAD, such as control point manipulation, are not appropriated for blade design, and the designers prefer to work with design parameters that possess a clear aerodynamic / hydrodynamic meaning. This method uses common design parameters for the geometry of propellers and produces a final B-spline surface for the geometry of the blades that can be used for the visualisation, calculations, and construction of the propeller. The method starts with the definition of a 3D grid of points that form the propeller blades based on the 2D definition of a series of cross-sectional profiles at several radial locations. Propeller blades are very thin objects with great changes of curvature, and if standard B-spline techniques are used, they cannot be modelled well under a tolerance unless a large number of control points is used, producing very complex surfaces. The inclination and twist of the blades are given by rake and pitch angles, quite common in the design procedures. The method stresses the fitting of the blade's leading edge which has great effect on the propeller behaviour and geometrically has a small curvature radius in comparison with the rest of the blades.
Authors:Haichao Wang; Zhijiang Wang; Pengfei Bai; Shengsun Hu; Yanshen Zhang; Ren Wang Pages: 1 - 7 Abstract: Publication date: March 2018 Source:Advances in Engineering Software, Volume 117 Author(s): Haichao Wang, Zhijiang Wang, Pengfei Bai, Shengsun Hu, Yanshen Zhang, Ren Wang A segmented heat source is typically used in welding processes with high energy density and high welding speed, such as laser beam welding. In such welding processes, the intense heat source runs through one segment so quickly that the heating processes in each segment could be considered as a segmented heat source with the largest heat flux heating in a short time. It is then possible to use a segmented heat source model to reduce the computation time. In the present work, a feasible and highly efficient optimized segmented heat source, in which cooling time is considered, was proposed to extend its application area. The optimized segmented heat source could be applied to simulate welding processes with various welding speeds and to simulate large structures with high efficiency. The axial strain in welding a pipe with external diameter of 510 mm and wall thickness of 13.5 mm by shielded metal arc welding was measured to verify the accuracy of the proposed heat source. The temperature filed characteristics and the prediction of welding deformation and its distribution were discussed to measure the accuracy and efficiency of the model with the proposed heat source. The model with the optimized segmented heat source predicts the welding deformation with higher accuracy compared to the model with the traditional segmented heat source; however, the efficiency was compromised. Its accuracy is in the range of 10% compared to the model with a double-ellipsoidal heat source, but it is more effective.
Authors:Weihao Chai; Xiandong Liu; Yingchun Shan; Xiaofei Wan; Er Jiang Pages: 1 - 8 Abstract: Publication date: February 2018 Source:Advances in Engineering Software, Volume 116 Author(s): Weihao Chai, Xiandong Liu, Yingchun Shan, Xiaofei Wan, Er Jiang Using the long glass fiber reinforced thermoplastic composite (LGFT) in wheel manufacture is an important way for the lightweight design of automotive wheel. The bending fatigue test of automotive wheel is one of the key tests to ensure a safe wheel. Aiming at minimizing the development cost, this paper investigates a simulation method of the bending fatigue test considering the anisotropic property of the LGFT. First and foremost, the anisotropic material model of the LGFT is established based on the tensile test of LGFT specimens. With the fiber orientation and distribution of the wheel from the injection molding simulation, the anisotropic material property of the LGFT wheel is obtained. Then the simulation model of the bending fatigue test platform is established, with which the strength simulation of the LGFT wheel is conducted. To validate the accuracy of the simulation method and the anisotropic material model, the simulation results from the anisotropic/isotropic material models and the experimental result from the physical bending fatigue test are compared and analyzed. It can be seen that the result from the anisotropic material model satisfies the requirements well and is more accurate than that from the isotropic material model. The research shows that it is necessary to consider the anisotropic property in the strength simulation of the bending fatigue test of the LGFT wheel, and the simulation method considering anisotropic property provides an effective way for the strength simulation of other components made of the fiber reinforced thermoplastics.
Authors:Jinhuan Zhang; Zhenggui Zhou; Hui Cao; Qi Li Pages: 9 - 22 Abstract: Publication date: February 2018 Source:Advances in Engineering Software, Volume 116 Author(s): Jinhuan Zhang, Zhenggui Zhou, Hui Cao, Qi Li Axial compressors are widely used in industrial applications; high efficiencies and large operating ranges are main performance requirements for their aerodynamic designs. In this study, an aerodynamic design method for multi-stage axial compressors is proposed. The design of the first stage is based on the S1/S2 stream surface theory, and a repeated stage design method is proposed for subsequent stage designs. And in the first stage design, a multi-point optimization design is used to design the rotor and stator blade profiles for both high efficiencies and large operating ranges. A five repeated stage axial compressor with a large mass flow rate has been designed by this design method. Analysis results of the rotor and stator three-dimensional flow fields indicate that the flow is primarily limited to the S1 stream surface and the two-dimensional design method is applicable; the flow in subsequent stages possesses similar characteristics as the flow in first stage. In addition, the designed five-stage axial compressor has a total pressure ratio that approaches the design goal and a stability margin that exceeds the design goal. The novelty of this study includes two parts, one is the usage of multi-point optimization method for rotor and stator blade design, and the other is the repeated stage design method.
Authors:Nikolaos K. Psyrras; Anastasios G. Sextos Pages: 23 - 35 Abstract: Publication date: February 2018 Source:Advances in Engineering Software, Volume 116 Author(s): Nikolaos K. Psyrras, Anastasios G. Sextos Despite the breadth of the available finite element codes for seismic analysis and assessment, the associated complexity in use and the generality in orientation are likely to increase the epistemic uncertainty involved in the models, particularly in nonlinear analysis procedures. Thus, it is of interest to develop tools for improving the reliable use of existing structural engineering software. This paper aims to present the capabilities of Build-X, a recently developed knowledge-based system tailored to the prediction of the seismic response of 3D buildings. This expert system features a simple visual user interface that supports the structural engineer throughout the structural configuration of a building, providing expert suggestions as to critical modeling decisions, and automations that increase the reliability of the analysis and accelerate the pre-processing stage. Build-X is linked with OpenSees, a widely used script-based freeware for seismic analysis of structures, which is utilized to perform the core finite element analysis. Post-processing tasks are easy to handle through the graphical engine of the system developed. A verification study demonstrates the efficiency of the system and reliability of the results generated, pointing to the way in which Build-X may serve as a useful tool for the seismic analysis of newly designed buildings and the assessment of existing ones at reduced computational cost and modeling uncertainty.
Authors:Zhilin An; Tiantang Yu; Tinh Quoc Bui; Chao Wang; Ngoc Anh Trinh Pages: 36 - 49 Abstract: Publication date: February 2018 Source:Advances in Engineering Software, Volume 116 Author(s): Zhilin An, Tiantang Yu, Tinh Quoc Bui, Chao Wang, Ngoc Anh Trinh In this paper, the recently developed hybrid numerical method based on isogeometric analysis (IGA) and boundary element method (BEM), named as IGABEM, is further extended to study steady heat transfer problems in two dimensions (2D). The IGA employs spline basis functions (e.g., NURBS) as shape functions for geometric description and field approximation. The NURBS only describe the boundary of objects, and the BEM also directly deals with the boundaries. Therefore, the combined IGABEM is highly attractive as it takes advantages of the common boundary representation of both the IGA and the BEM. The formulation of IGABEM for steady heat transfer is derived, and its performance and accuracy are verified through numerical test cases by comparing the obtained results with analytical and finite element method solutions. The convergence of the developed approach for steady heat transfer problems is also analyzed. The computer codes of the IGABEM developed for steady heat transfer analysis can be accessed at: http://www.idmes.cn/codes.html.
Authors:Yong Cai; Guangyao Li; Wenyang Liu Pages: 50 - 59 Abstract: Publication date: February 2018 Source:Advances in Engineering Software, Volume 116 Author(s): Yong Cai, Guangyao Li, Wenyang Liu Hardware accelerators are becoming increasingly important in boosting high performance computing systems. In this study, we develop a parallel explicit finite element (FE) analysis system based on a many integrated core (MIC) architecture for fast simulation of nonlinear dynamic problems of plate and shell structures. To minimize data transfer between heterogeneous architectures, parallel computation of the all explicit FE calculation is realized by developing a vectorized thread-level parallelism algorithm. The parallelism includes a novel dependency relationship link based method for efficiently solving parallel explicit shell element equations. A heterogeneous model is established to overlap data transfer and offloaded computation, and thus reduce the time required for large intermediate data storage in the actual engineering nonlinear problem simulation. Finally, a high performance nonlinear dynamic simulation system is developed. The simulations of benchmarks and engineering problems show that the parallel computing method proposed in this paper can give full play to the hardware performance of MIC architecture and effectively improve the computation efficiency of an explicit FE solution. For a bus body model containing approximately 3.8 million degrees of freedom, the computational speed is improved 17 times over CPU sequential computation, and the relative speedup grows with the increasing number of threads, the highest relative speedup exceeds 80.
Authors:Chenzhi CAI; Cheuk Ming MAK Pages: 60 - 66 Abstract: Publication date: February 2018 Source:Advances in Engineering Software, Volume 116 Author(s): Chenzhi CAI, Cheuk Ming MAK Helmholtz resonator (HR) is one of the most basic acoustic models and has been widely used in engineering applications due to its simple, tunable and durable characteristics. The transmission loss index is mainly used to evaluate the acoustic transmission performance. Based on the transmission loss index, this paper proposes the noise attenuation capacity index as one of the key parameters to evaluate the noise attenuation performance of a HR. The noise attenuation capacity is defined as the integral of transmission loss in the frequency domain. The theoretical formula of a HR's noise attenuation capacity is first derived in this study. It indicates that the noise attenuation capacity of a HR is only related to geometries of the neck and duct's cross-sectional area. The cavity volume has no effects on its noise attenuation capacity. The proposed theoretical formula of a HR's noise attenuation capacity is validated by Finite Element Method (FEM) simulation using commercial software (COMSOL Multiphysics). The proposed noise attenuation capacity of a HR should therefore be considered as one of the main acoustic characteristics of a HR. It is hoped that the present study could provide a stepping stone for the investigation of the HR's or other silencers’ noise attenuation capacity and potential applications in all research areas in respect of the HR.
Authors:Uwe Reuter; Ahmad Sultan; Dirk S. Reischl Pages: 67 - 79 Abstract: Publication date: February 2018 Source:Advances in Engineering Software, Volume 116 Author(s): Uwe Reuter, Ahmad Sultan, Dirk S. Reischl This study introduces an enhanced approach for concrete failure criterion, which is strongly needed for a realistic simulation of concrete behavior, by employing machine learning approaches instead of the traditional models of failure surfaces. Since the shape of concrete failure surfaces is not exactly known, a general shape function for verification purposes of the machine learning approaches is introduced. Artificial neural networks, support vector machines, and support vector regression are adapted to model realizations of this general shape function with different noise levels. After the successful fitting of these surfaces, the algorithms are employed to model the failure surface of C25 concrete starting from 88 experimental tests. The three approaches are able to fit the experimental data with low error and are compared to one another. Drucker–Prager and Bresler–Pister surfaces are solved for the same experimental data and compared with the support vector regression surface. The main advantage of machine learning approaches is that they are model-free approaches which eliminate the need of new models for new concrete types.
Authors:Bo Wang; Bing Pan Pages: 80 - 88 Abstract: Publication date: February 2018 Source:Advances in Engineering Software, Volume 116 Author(s): Bo Wang, Bing Pan Digital volume correlation (DVC) has been widely accepted as an effective experimental technique for quantifying full-field internal 3D deformation of solid materials and structures under external loading. However, conventional DVC using a fixed reference volume image generally fails when serious decorrelation occurs in deformed volume images due to large deformation or other reasons. In this work, an accurate and simple incremental DVC method with nearest subvolume offset is proposed for large deformation measurement. Specifically, the reference subvolumes in the updated reference volume images are translated to nearest integer-voxel positions, rather than being interpolated at subvoxel locations. The translated reference subvolumes, within which all correlation points locate at integer-voxel positions, are then tracked in the rest deformed volume images to retrieve incremental displacement fields. The obtained incremental displacement fields are then accumulated to previously obtained displacement fields to determine the overall displacements. By using the simple nearest subvolume offset approach, subvoxel intensity interpolation for the updated reference subvolumes is entirely avoided, thus not only eliminating the bias error associated with imperfect subvoxel intensity interpolation, but also increasing the computational efficiency of incremental DVC calculation by approximately 2.5 times. The accuracy, efficiency and practicality of the presented incremental DVC are demonstrated by analyzing two sets of volume images with large deformation generated in numerically simulated and real-world experiments.
Authors:Jie Gao; Hao Li; Liang Gao; Mi Xiao Pages: 89 - 102 Abstract: Publication date: February 2018 Source:Advances in Engineering Software, Volume 116 Author(s): Jie Gao, Hao Li, Liang Gao, Mi Xiao This paper proposes an effective method for the design of 3D micro-structured materials to attain extreme mechanical properties, which integrates the firstly developed 3D energy-based homogenization method (EBHM) with the parametric level set method (PLSM). In the 3D EBHM, a reasonable classification of nodes in periodic material microstructures is introduced to develop the 3D periodic boundary formulation consisting of 3D periodic boundary conditions, 3D boundary constraint equations and the reduced linearly elastic equilibrium equation. Then, the effective elasticity properties of material microstructures are evaluated by the average stress and strain theorems rather than the asymptotic theory. Meanwhile, the PLSM is applied to optimize microstructural shape and topology because of its positive characteristics, like the perfect demonstration of geometrical features and high optimization efficiency. Numerical examples are provided to demonstrate the advantages of the proposed design method. Results indicate that the optimized 3D material microstructures with expected effective properties are featured with smooth structural boundaries and clear interfaces.
Authors:Zhen-Zhong Hu; Pei-Long Tian; Sun-Wei Li; Jian-Ping Zhang Pages: 1 - 16 Abstract: Publication date: January 2018 Source:Advances in Engineering Software, Volume 115 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:Yong Jie Zhao; Yun Hui Yan; Ke Chen Song; Hao Nan Li Pages: 17 - 25 Abstract: Publication date: January 2018 Source:Advances in Engineering Software, Volume 115 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:Jisong Zhang; Haijiang Li; Yinghua Zhao; Guoqian Ren Pages: 26 - 39 Abstract: Publication date: January 2018 Source:Advances in Engineering Software, Volume 115 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:Dongquan Wu; Hongyang Jing; Lianyong Xu; Lei Zhao; Yongdian Han Pages: 40 - 51 Abstract: Publication date: January 2018 Source:Advances in Engineering Software, Volume 115 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:S. Castillo-Rivera; M. Tomas-Rodriguez Pages: 52 - 65 Abstract: Publication date: January 2018 Source:Advances in Engineering Software, Volume 115 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 Pages: 66 - 74 Abstract: Publication date: January 2018 Source:Advances in Engineering Software, Volume 115 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:X.X. Li; W.D. Li; F.Z. He Pages: 75 - 86 Abstract: Publication date: January 2018 Source:Advances in Engineering Software, Volume 115 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:Ji-Hyun Jung; Dae-Sung Bae Pages: 87 - 102 Abstract: Publication date: January 2018 Source:Advances in Engineering Software, Volume 115 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.
Authors:Jian Zhang; Abdelkader El Kamel Pages: 103 - 111 Abstract: Publication date: January 2018 Source:Advances in Engineering Software, Volume 115 Author(s): Jian Zhang, Abdelkader El Kamel Virtual traffic simulation plays an important role in easing traffic congestion and reducing traffic pollution. As the transportation network expands, the former rule-based mobility models showed several limitations in producing convincing virtual vehicles. A more realistic model with example-based method is in demand. In this paper, a neural network is employed with carefully selected traffic trajectory data. The virtual vehicle production is driven by the proposed mobility model and organized by a specified structure. Then, the virtual traffic simulation could be given for an indicated scenario.
Authors:Zaher Mundher Yaseen; Ravinesh C. Deo; Ameer Hilal; Abbas M. Abd; Laura Cornejo Bueno; Sancho Salcedo-Sanz; Moncef L. Nehdi Pages: 112 - 125 Abstract: Publication date: January 2018 Source:Advances in Engineering Software, Volume 115 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:Silvia Tolo; Edoardo Patelli; Michael Beer Pages: 126 - 148 Abstract: Publication date: January 2018 Source:Advances in Engineering Software, Volume 115 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.
Authors:M.J. Esfandiari; G.S. Urgessa; S. Sheikholarefin; S.H. Dehghan Manshadi Pages: 149 - 160 Abstract: Publication date: January 2018 Source:Advances in Engineering Software, Volume 115 Author(s): M.J. Esfandiari, G.S. Urgessa, S. Sheikholarefin, S.H. Dehghan Manshadi Evolutionary optimization algorithms are widely used for solving optimization problems. However, in the realm of real-world structures finding the optimum design would be difficult and time-consuming due to large number of design variables, enormous size of the search space, and availability of numerous constraints. As a result, holistic optimization approaches that consider architectural and other practical requirements in addition to required code provisions are rather limited in real-world structures. This paper presents an innovative algorithm combining multi-criterion decision-making (DM) and Particle Swarm Optimization (PSO), which is called DMPSO, for accelerating convergence toward optimum solution in 3D reinforced concrete (RC) frames. All practical requirements are considered for obtaining directly constructible designs without any further modifications. The effectiveness of the proposed algorithm is illustrated in optimization of 3D RC frames subjected to lateral seismic forces according to ASCE 7 requirements. The results confirm the ability of the proposed DMPSO algorithm to efficiently find optimal solutions for 3D RC optimization problems.
Authors:Wenjie Zuo; Yayun Lu; Xing Zhao; Jiantao Bai Pages: 161 - 167 Abstract: Publication date: January 2018 Source:Advances in Engineering Software, Volume 115 Author(s): Wenjie Zuo, Yayun Lu, Xing Zhao, Jiantao Bai Thin-walled beam structure can be used to efficiently predict the performances of automobile frame for conceptual design. However, it is an open issue to acquire an accurate cross-sectional shape of A-pillar structure considering both rigidity and driver's field of view (DFOV). This paper proposes an approach to calculate the cross-sectional rigidity and DFOV. Firstly, formulations of cross-sectional properties, including open, single-cell, double-cell, three-cell, four-cell section, are summarized. Secondly, the obstruction angle is introduced to describe DFOV, which is acquired by a nonlinear optimization model. Finally, a A-pillar example of Toyota RAV4, solved by the developed software – CarFrame, proves that the proposed method can be completely applied at the conceptual design of the automobile structure.
Authors:Mohammad Malekan; Leandro L. Silva; Felicio B. Barros; Roque L.S. Pitangueira; Samuel S. Penna Pages: 168 - 193 Abstract: Publication date: January 2018 Source:Advances in Engineering Software, Volume 115 Author(s): Mohammad Malekan, Leandro L. Silva, Felicio B. Barros, Roque L.S. Pitangueira, Samuel S. Penna This work presents an object-oriented implementation of the G/XFEM to model the crack nucleation and propagation in structures made of either linear or nonlinear materials. A discontinuous function along with the asymptotic crack-tip displacement fields are used to represent the crack without explicitly meshing its surfaces. Different approach are explained in detail that are used to capture the crack nucleation within the model and also determine the crack propagation path for various problems. Stress intensity factor and singularity of the localization tensor (which provides the classical strain localization condition) can be used to determine the crack propagation direction for linear elastic materials and nonlinear material models, respectively. For nonlinear material model, the cohesive forces acting on the crack plane are simulated in the enrichment process by incorporating a discrete constitutive model. Several algorithms and strategies have been implemented, within an object-oriented framework in Java, called INSANE. This implementation will be presented in detail by solving different two-dimensional problems, for both linear and nonlinear material models, in order to show the robustness and accuracy of the proposed method. The numerical results are compared with the reference solutions from the analytical, numerical or experimental results, where applicable.
Authors:Michael Meister; Massoud Rezavand; Christian Ebner; Thomas Pümpel; Wolfgang Rauch Pages: 194 - 203 Abstract: Publication date: January 2018 Source:Advances in Engineering Software, Volume 115 Author(s): Michael Meister, Massoud Rezavand, Christian Ebner, Thomas Pümpel, Wolfgang Rauch In this article, a finite volume method based CFD analysis of the mixing of Newtonian and non-Newtonian flows in anaerobic digesters is conducted. The multiple reference frame method is used to model the mixing which is induced by an impeller rotating within a mechanical draft tube. Moreover, the feeding of biomass is considered in the model formulation. Following the validation of the method against reference data, the mixing of cylindrical and egg-shaped digesters is investigated. The distinguishing feature of this article is that the theoretical findings are adopted for the operation of a real-life anaerobic digester. In the context of a case study slurry flows with high total solids concentrations are investigated.
Authors:Jikai Liu; Lei Li; Yongsheng Ma Pages: 204 - 216 Abstract: Publication date: January 2018 Source:Advances in Engineering Software, Volume 115 Author(s): Jikai Liu, Lei Li, Yongsheng Ma In the authors’ earlier work [1], a component length scale control functional was proposed to regulate the topology evolution with uniform thickness distribution; however, the sensitivity result was numerically calculated with certain approximation. In order to make this functional better work for complex design problems, the sensitivity result is now analytically calculated with the aid of the structural skeleton-based non-signed distance level set field. More importantly, this component length scale control functional has been upgraded to eliminate the need of pre-specifying the length scale target. By using control functional instead of constraints, a benefit is that the structural performance and length scale control effect can be balanced by the weight factor, because it is not always necessary to strictly achieve the uniform thickness distribution while drastically compromising the structural performance. Therefore, this work studies the uniform thickness control in a multi-objective manner. Effectiveness of the proposed method is proved through a few 2D and 3D numerical case studies.
Authors:Yaqing Zhang; Wenjie Ge; Yonghong Zhang; Zhenfei Zhao Pages: 217 - 229 Abstract: Publication date: January 2018 Source:Advances in Engineering Software, Volume 115 Author(s): Yaqing Zhang, Wenjie Ge, Yonghong Zhang, Zhenfei Zhao A topology optimization method, based on a direct coupled finite element (FE) and element-free Galerkin (EFG) method, is developed in this study, for reducing the computational cost of EFG-based topology optimization methods. Comparing with other coupling methods, the new coupling method can guarantee higher order continuity of the shape function in the coupling region and it can be implemented easily. A constrained centroidal Voronoi tessellation (CCVT) algorithm associated with density variable is developed to generate updated EFG nodes for the discretizing of EFG domain during the iterations which accelerates the optimization convergence. To reduce the computational cost, an adaptive multi-level Gauss quadrature scheme is introduced for numerical integration. Several examples are given to demonstrate the effectiveness of the proposed approach and the proposal shows advantages comparing with some other topology optimization methods.
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