Authors:C.T. Wu; N. Ma; Y. Guo; W. Hu; K. Takada; H. Okada; K. Saito Pages: 1 - 12 Abstract: Publication date: September 2018 Source:Advances in Engineering Software, Volume 123 Author(s): C.T. Wu, N. Ma, Y. Guo, W. Hu, K. Takada, H. Okada, K. Saito This paper presents a finite element continuous-discontinuous approach for the dynamic ductile failure analysis of shell structures. The continuum damage model based on continuous displacements is used in the continuous stage to describe the diffuse micro-cracking in ductile failure of high-strength steel before a macro-crack is formed. In the context of a fully integrated shear deformable shell formulation, a nonlocal modeling procedure based on a projection of mid-plane reference surface is introduced to regularize the element-wise strain fields induced by the continuum damage model. In the discontinuous stage, an incorporation of velocity discontinuities in shell finite elements is pursued by XFEM method when the damage variable exceeds a critical value and the transition from a continuous to a discontinuous model is permitted. A phantom-node approach is employed in the XFEM method to simplify the numerical treatment of velocity discontinuities in the shell finite element formulation. Several numerical benchmarks are examined using the explicit dynamics analysis and the results are compared with the experimental data to demonstrate the effectiveness and accuracy of the proposed method.
Authors:Roberto Fernandez Martinez; Ruben Lostado Lorza; Ana A. Santos Delgado; Nelson O. Piedra Pullaguari Pages: 13 - 24 Abstract: Publication date: September 2018 Source:Advances in Engineering Software, Volume 123 Author(s): Roberto Fernandez Martinez, Ruben Lostado Lorza, Ana A. Santos Delgado, Nelson O. Piedra Pullaguari Double-row Tapered Roller Bearings are mechanical devices that have been designed to support a combination of loads that are fixed on an optimal presetting to ensure correct working conditions. The emergence of high contact stresses, fatigue spalling and pitting on the bearing railway makes it important to have a tool that enables knowing in advance whether certain presetting loads will lead to excellent working conditions or the opposite. This work proposes a methodology to classify the working condition on the basis of the values of presenting loads on four classes. To achieve this goal, a three-dimensional Finite Element (FE) model was generated. Later, a design of experiments was designed to provide the greatest amount of information by reducing the computational cost of the simulations based on FE models. Then, one of the four classes of working conditions was assigned to each of the experiments. Later, a statistical analysis and machine learning techniques were used to create classification models. Feature transformation and reduction, algorithm parameter tuning and validation methods were used to achieve robust classification models. The best results were obtained based on flexible discriminant analysis. As it provided acceptable accuracy, both the methodology and final model were validated.
Authors:Yaqing Zhang; Wenjie Ge; Yonghong Zhang; Zhenfei Zhao; Jinwang Zhang Pages: 25 - 37 Abstract: Publication date: September 2018 Source:Advances in Engineering Software, Volume 123 Author(s): Yaqing Zhang, Wenjie Ge, Yonghong Zhang, Zhenfei Zhao, Jinwang Zhang Meshless methods can solve large classes of problems where grid-based methods are awkward to handle, such as the discretizing of complicated structures, the remeshing in large displacement problems and so on. In this study, a meshless-based topology optimization is proposed for large displacement problems of nonlinear hyperelastic structure. In order to circumvent nonlinear numerical instabilities, the linear and nonlinear analyses are set in the low- and high-stiffness region, respectively. Thus, an interpolation scheme is adopted for hybridizing the linearity and nonlinearity in the structure analysis. A directly coupled finite element and meshless method is introduced to reduce the computational cost of meshless methods and an auto-coupling strategy is proposed for the adaptive arrangement of finite element and meshless regions. Several numerical examples are given to demonstrate the effectiveness of the proposed method.
Authors:Yan Lin; Jingyi He; Kai Li Pages: 38 - 50 Abstract: Publication date: September 2018 Source:Advances in Engineering Software, Volume 123 Author(s): Yan Lin, Jingyi He, Kai Li Twin-skeg ship has better hydrodynamic performances than regular ship, however, it is still difficult to obtain an accurate relationship between skeg design and overall hydrodynamic performances. Resistance optimization is the major concern of developing twin-skeg ship. This paper proposes a combined approach for hull form design optimization of twin-skeg ship by using computational fluid dynamics (CFD) calculation and surrogate model. Main design parameters of skeg geometry and arrangement could be determined from the design domain by using the proposed method. Parametric modeling technology is adopted for performing design evaluations in an automatic manner with different design parameter combinations. A twin-skeg fishing vessel is selected as research object. In the proposed method, the sample set for constructing surrogate models is generated by using Optimal Latin Hypercube Sampling (OLHS) method, the corresponding responses are calculated through CFD simulations, and then the surrogate models are constructed by using Kriging modeling method, which represent the mathematical relationship between input design variables (skeg shape design variables) and output objective functions (resistance values under four different working conditions). The functional analysis of variance (ANOVA) is performed to investigate how much influence the design variables have on the objective functions. Finally, a multi-objective evolutionary algorithm (NSGA-II) is used to obtain the optimal solution, which shows 5.4% average decrease in the total resistance than the original design. The CFD calculation results of the optimal solution show that the proposed method can achieve minimum resistance design with high accuracy and low time cost.
Authors:Wanzhong Zhao; Zhongkai Luan; Chunyan Wang Pages: 51 - 61 Abstract: Publication date: September 2018 Source:Advances in Engineering Software, Volume 123 Author(s): Wanzhong Zhao, Zhongkai Luan, Chunyan Wang To improve the handling stability as well as reduce the steering energy consumption of heavy commercial vehicle, a novel electric-hydraulic hybrid power steering (E-HHPS) system with multiple steering modes is presented, which enables the vehicle to acquire the steering handiness at low speed and better steering road feeling at high speed by switching the actuator unit according to the current working condition. In this paper, to achieve the design goals of E-HHPS system, which are to reduce steering energy consumption and improve steering stability, three evaluation indexes of E-HHPS system are established, which convert the E-HHPS system parameter optimization problem into a multi-objective optimization model. Because it is difficult to approximate the Pareto front of the transformed optimization model by basic algorithms, a multi-objective particle swarm optimization algorithm based on adaptive decomposition (MOPSO/AD) is proposed. Test functions are used to verify the performance of the algorithm and test results show that the MOPSO/AD algorithm has better comprehensive performance and stability compared with the basic MOPSO algorithm and MOEA/D algorithm. The MOPSO/AD algorithm is applied to solve the E-HHPS system optimization model and simulation results show that the proposed MOPSO/AD algorithm has better convergence in solving the E-HHPS parameter optimization problem compared with MOPSO, which enables the optimized E-HHPS system has good handling stability and low steering energy consumption.
Authors:Yuanlong Wang; Wanzhong Zhao; Guan Zhou; Qiang Gao; Chunyan Wang Pages: 1 - 12 Abstract: Publication date: August 2018 Source:Advances in Engineering Software, Volume 122 Author(s): Yuanlong Wang, Wanzhong Zhao, Guan Zhou, Qiang Gao, Chunyan Wang Comparing with traditional honeycomb structures, Negative Poisson's Ratio (NPR) structures had better mechanical performances in some certain respects, especially the shear modulus and fracture toughness. However, few publications focused on the cylinder-shape NPR structure, which influence the diversity and possibility of NPR structure applications. In this paper, a cylindrical NPR structure was introduced and applied as a suspension jounce bumper in order to solve the issue that the ideal uniaxial compression load-displacement curve sometimes cannot be realized by traditional Polyurethane (PU) jounce bumper. The load-displacement curve of NPR jounce bumper was proved to be smoother and more ideal than that of traditional jounce bumper. Nevertheless, the influences of NPR jounce bumper on the suspension mechanical performance and vehicle ride comfort were not comprehended yet. In this study, the traditional and NPR jounce bumpers were both assembled into virtual prototypes of Macpherson, double wishbone and multi-link suspensions to conduct single wheel travel virtual tests. The results indicated that NPR jounce bumper can achieve more ideal wheel force vs. jounce height curve without adjusting free travel, which is beneficial to spare precise suspension space. Furthermore, a jounce bumper evaluation method using pulse ride comfort was proposed in this paper. The virtual ride comfort tests of travelling through bump and pothole were conducted using established vehicle virtual prototype. The maximum vertical accelerations and weighted root mean square (RMS) of acceleration of vehicle centroid at most speeds were reduced applying NPR jounce bumper. Thus, the NPR jounce bumper can apparently improve vehicle ride comfort.
Authors:Delfim Soares Pages: 13 - 21 Abstract: Publication date: August 2018 Source:Advances in Engineering Software, Volume 122 Author(s): Delfim Soares In this work, an enhanced explicit technique is proposed to analyze hyperbolic heat conduction models. As usual, the explicit approach allows the solution of the problem to be carried out without dealing with any system of equations, featuring a very efficient methodology. In addition, the proposed technique enables algorithmic dissipation, allowing the influence of spurious high modes to be properly eliminated, without introducing significant period elongation and amplitude decay errors into the analysis. As an explicit approach, the technique is conditionally stable; however, it exhibits high stability limits (its critical time-step is around 1.8 times that of the Central Difference Method), emphasizing its effectiveness. The technique is very accurate, truly self-starting and extremely direct to implement. At the end of the manuscript, numerical results are presented, illustrating the good performance of the discussed technique.
Authors:Ahmed Guerine; Tarek Merzouki; Abdelkhalak El Hami; Tarak Ben Zineb Pages: 22 - 30 Abstract: Publication date: August 2018 Source:Advances in Engineering Software, Volume 122 Author(s): Ahmed Guerine, Tarek Merzouki, Abdelkhalak El Hami, Tarak Ben Zineb In this paper, we propose a method for taking into account uncertainties of a micro-pump system using Shape Memory Alloy (SMA), based on the perturbation method. The proposed method is used to determine the thermo-mechanical response of a system. Comparisons with the mean value reference solution, illustrate the efficiency of the proposed method. The results are discussed in order to investigate the influence of the most influential parameters of the thermomechanical SMA model. The simulation results are obtained by the proposed method for static analysis with uncertainties.The perturbation method results are compared with the mean value reference solution. The results are discussed in order to investigate the influence of the Young's modulus E, the two transformations strain magnitude ɛ t r a c T and ɛ t r a c T F A , the martensite start Ms and austenite finish Af temperatures and the stress reorientation F ε on the static response of a micro-pump system.
Authors:Shuwei Zhou; Timon Rabczuk; Xiaoying Zhuang Pages: 31 - 49 Abstract: Publication date: August 2018 Source:Advances in Engineering Software, Volume 122 Author(s): Shuwei Zhou, Timon Rabczuk, Xiaoying Zhuang The phase-field model (PFM) represents the crack geometry in a diffusive way without introducing sharp discontinuities. This feature enables PFM to effectively model crack propagation compared with numerical methods based on discrete crack model, especially for complex crack patterns. Due to the involvement of “phased field”, phase-field method can be essentially treated a multifield problem even for pure mechanical problem. Therefore, it is supposed that the implementation of PFM based on a software developer that especially supports the solution of multifield problems should be more effective, simpler and more efficient than PFM implemented on a general finite element software. In this work, the authors aim to devise a simple and efficient implementation of phase-field model for the modelling of quasi-static and dynamic fracture in the general purpose commercial software developer, COMSOL Multiphysics. Notably only the tensile stress induced crack is accounted for crack evolution by using the decomposition of elastic strain energy. The width of the diffusive crack is controlled by a length-scale parameter. Equations that govern body motion and phase-field evolution are written into different modules in COMSOL, which are then coupled to a whole system to be solved. A staggered scheme is adopted to solve the coupled system and each module is solved sequentially during one time step. A number of 2D and 3D examples are tested to investigate the performance of the present implementation. Our simulations show good agreement with previous works, indicating the feasibility and validity of the COMSOL implementation of PFM.
Authors:HV Kurugodu; S Bordoloi; Y Hong; Ankit Garg; Akhil Garg; S Sreedeep; AH Gandomi Pages: 50 - 61 Abstract: Publication date: August 2018 Source:Advances in Engineering Software, Volume 122 Author(s): HV Kurugodu, S Bordoloi, Y Hong, Ankit Garg, Akhil Garg, S Sreedeep, AH Gandomi Unconfined compressive strength (UCS) of soil is one of the basic index parameters for representing the compressive bearing strength of soil. Fiber reinforced soil is one of the most popular and practical ground improvement approaches used in geotechnical infrastructures. Analytical models for estimating UCS of soil-fiber composites have been developed in the literature. However, these models rarely incorporate the combined effects of dynamic field parameters such as fiber content, soil moisture, and density. These effects can be studied by the development of a holistic model based on a dimensionless strength improvement factor (SIF), which is defined as the ratio of UCS of reinforced soil to the unreinforced UCS. The current model estimating SIF indicates the improvement expected in UCS of soil-PP fiber composite based on the three design conditions such as fiber content, soil density, and moisture content. For this purpose, a series of 108 laboratory tests were first conducted to measure UCS of both fiber-reinforced soil and unreinforced soil under different fiber contents, soil density, and soil moisture content. Clayey silt soil and commercially used polypropylene (PP) fibers were selected in this study as soil and fiber material respectively. Genetic programming (GP) approach was then used to formulate models based on the measured data. The hidden non-linear relationships between SIF and the three inputs were determined by sensitivity and parametric analysis of the GP model. It was found that the moisture content in the soil has the highest influence on the strength factor that accounts for the change in strength. Coupled effects of soil parameters (soil moisture, soil density) and fiber content have been studied using parametric analysis which includes different possible field conditions (parameters). The results have been discussed along with the reinforcement mechanism of PP fiber for different soil conditions. It is believed that the robust GP model developed will be useful to determine optimum input values for designing safe bearing foundation soils which are reinforced with PP fibers.
Authors:Hao Dong; Junzhi Cui; Yufeng Nie; Zihao Yang; Ziqiang Wang Pages: 1 - 12 Abstract: Publication date: July 2018 Source:Advances in Engineering Software, Volume 121 Author(s): Hao Dong, Junzhi Cui, Yufeng Nie, Zihao Yang, Ziqiang Wang This study develops a novel high-order three-scale (HOTS) computational method for heat conduction problems of axisymmetric composite structures with multiple spatial scales. The heterogeneities of the composites are taken into account by periodic distributions of unit cells on the mesoscale and microscale. Firstly, the multiscale asymptotic analysis for these multiscale problems is given detailedly. Based on the above-mentioned analysis, the new unified micro-meso-macro HOTS approximate solutions are successfully constructed for these multiscale problems. Two classes of auxiliary cell functions are established on the mesoscale and microscale. Then, the error analyses for the conventional two-scale solutions, low-order three-scale (LOTS) solutions and HOTS solutions are obtained in the pointwise sense, which illustrate the necessity of developing HOTS solutions for simulating the heat conduction behaviors of composite structures with multiple periodic configurations. Furthermore, the corresponding HOTS numerical algorithm based on finite element method (FEM) is brought forward in details. Finally, some numerical examples are presented to verify the feasibility and validity of our HOTS computational method. In this paper, a unified three-scale computational framework is established for heat conduction problems of axisymmetric composite structures with multiple spatial scales.
Authors:Yaoyao Wang; Fei Yan; Surong Jiang; Bai Chen Pages: 13 - 25 Abstract: Publication date: July 2018 Source:Advances in Engineering Software, Volume 121 Author(s): Yaoyao Wang, Fei Yan, Surong Jiang, Bai Chen For the high performance control of cable-driven manipulators, a novel time delay control (TDC) scheme with adaptive fractional-order nonsingular terminal sliding mode (AFONTSM) is presented and studied in this work. The presented control scheme uses time delay estimation (TDE) as its basic framework, which can effectively obtain a fascinating model-free feature just using the time-delayed information of the closed-loop control system. Afterwards, a novel AFONTSM control scheme is applied to provide with good comprehensive performance under complicated lumped disturbance in both reaching and sliding phases. The presented control method can be easily applied in real situations thanks to TDE, meanwhile satisfactory control performance can be guaranteed benefiting from the adopted AFONTSM error dynamics. Stability analysis is given based on Lyapunov stability theory. Finally, the effectiveness and superiorities of our newly designed control scheme are validated through 2-DOFs (degree of freedoms) comparative simulations and experiments.
Authors:Gang Hu; Junli Wu; Xinqiang Qin Pages: 26 - 38 Abstract: Publication date: July 2018 Source:Advances in Engineering Software, Volume 121 Author(s): Gang Hu, Junli Wu, Xinqiang Qin To solve the problem of shape adjustment for developable surfaces, we propose a novel method for constructing local controlled generalized developable H-Bézier surfaces with shape parameters. The generalized developable H-Bézier surfaces are designed by using control planes with generalized H-Bézier basis functions and their shapes can be adjusted by altering the values of shape parameters. When the shape parameters assume different values, a family of developable H-Bézier surfaces can be constructed, which retain the characteristics of the developable Bézier surfaces. Furthermore, we derive the necessary and sufficient conditions for G1 continuity, Farin-Boehm G2 continuity and G2 Beta continuity between two adjacent generalized developable H-Bézier surfaces. Finally, some properties of the new developable surfaces are discussed, and the influence rules of shape parameters on the new developable surfaces are studied. Modeling examples provided show that the proposed methods are effective and hence can greatly improve problem-solving abilities in engineering appearance design by adjusting the position and shape of developable surfaces.
Authors:Nicola Giuliani; Andrea Mola; Luca Heltai Pages: 39 - 58 Abstract: Publication date: July 2018 Source:Advances in Engineering Software, Volume 121 Author(s): Nicola Giuliani, Andrea Mola, Luca Heltai Many physical phenomena can be modelled using boundary integral equations, and discretised using the boundary element method (BEM). Such models only require the discretisation of the boundary of the domain, making the setup of the simulation straightforward and lowering the number of degrees of freedom. However, while many parallel efficient libraries are available for the Finite Element Method (FEM), the implementation of scalable BEM solvers still poses many challenges. We present the open source framework π-BEM (where π stands for parallel): a novel boundary element method solver, combining distributed and shared memory paradigms to achieve high scalability. π-BEM exploits high performance libraries and graph partitioning tools to deliver a parallel solver employing automatic domain decomposition, high order elements, local refinement capabilities, and exact geometry-adaptivity (using CAD files). A preliminary fast multipole accelerator is included in the implementation. Every aspect of the library is modular and easily extendible by the community. We discuss the internal structure of the code, and present some examples to demonstrate the reliability and scalability of our implementation.
Authors:Viet-Hung Truong; Seung-Eock Kim Pages: 59 - 74 Abstract: Publication date: July 2018 Source:Advances in Engineering Software, Volume 121 Author(s): Viet-Hung Truong, Seung-Eock Kim A robust method for sizing reliability-based design optimization (RBDO) of truss structures is developed by integrating nonlinear inelastic analysis, a structural reliability analysis method, and a proposed optimization method based on differential evolution (DE) algorithm. Both discrete and continuous optimizations are considered. Compared to conventional DE, three main improvements are introduced in the proposed optimization method such as: (1) a new mutation scheme based on p-best strategy to balance between local and global searches; (2) modifications of the scale factor and crossover rate parameters; (3) a multi-comparison technique to reduce the useless objective function evaluations. 20 test functions and 4 real-world examples are first considered to demonstrate the performance of the proposed optimization method for deterministic optimization problems. 3 nonlinear inelastic truss structures are then carried out to investigate the robustness of proposed RBDO method.
Authors:Fabrizio Greco; Paolo Lonetti Pages: 75 - 83 Abstract: Publication date: July 2018 Source:Advances in Engineering Software, Volume 121 Author(s): Fabrizio Greco, Paolo Lonetti A finite element modeling based on a moving mesh strategy is developed to predict Vehicle–Bridge Interaction (VBI) in moving load applications. The formulation is based on an Arbitrary Lagrangian–Eulerian (ALE) approach, which is able to reproduce the vehicle motion on the basis of a fixed-referential system and moving coordinate variables, representing the positions of the external system. Conceptually, the vehicle and the bridge are considered as an integrated system, in which wheel-bridge interaction as well as the internal forces are implemented by means of moving interface elements. The governing equations of the VBI are derived in the referential coordinate system, whereas the ones associated to bridge structure are not modified from the conventional formulation. Such task is achieved by means of proper projection operators, which define the mapping between the referential and material configurations, reproducing the contact forces between the substructures. The proposed model is quite general to be endorsed in classical FE approach, since it does not require specialized connections with conventional structural formulations. The accuracy and efficiency are verified by means of comparisons with existing numerical results available from the literature, including cases in which the bridge structure is affected by damage phenomena.
Authors:Ionuţ Dragoş Moldovan; Ildi Cismaşiu Pages: 98 - 119 Abstract: Publication date: July 2018 Source:Advances in Engineering Software, Volume 121 Author(s): Ionuţ Dragoş Moldovan, Ildi Cismaşiu FreeHyTE is a public, open-source and user-friendly software for the solution of initial boundary value problems using hybrid-Trefftz finite elements. FreeHyTE is designed to be straightforward to use, even by analysts unacquainted to the Trefftz elements, and amenable to expansion by researchers willing to test their new ideas without having to code common procedures from scratch. To support users, FreeHyTE features intuitive graphical interfaces, automatic mesh generators and adaptive p-refinement procedures. To support developers, FreeHyTE approaches Trefftz elements through a unifying perspective, applicable to hyperbolic, parabolic and elliptic boundary value problems alike. It provides standardized procedures in all phases of the algorithm, including data input, construction and manipulation of the solving system, and post-processing of the results. Moreover, the modular structure of FreeHyTE enables the integration of existing procedures into new modules with minimal coding effort. FreeHyTE’s distribution is free under the terms of the GNU General Public License and supported by theory, installation, user’s and developer’s manuals to quickly get new users and developers started.
Authors:Zhongmin Deng; Zhaopu Guo Pages: 120 - 130 Abstract: Publication date: July 2018 Source:Advances in Engineering Software, Volume 121 Author(s): Zhongmin Deng, Zhaopu Guo In this paper, a new interval finite element (FE) model updating strategy is proposed for interval identification of structural parameters in the aspect of uncertainty propagation and uncertainty quantification. The accurate interval estimation of system responses can be efficiently obtained by application of Monte Carlo (MC) simulation combined with surrogate models. By means of the concept of interval length, a novel quantitative index named as interval overlap ratio (IOR) is constructed to characterize the agreement of interval distributions between analytical data and measured data. Two optimization problems are constructed and solved for estimating the nominal values and interval radii of uncertain structural parameters. Finally, the numerical and experimental case studies are given to illustrate the feasibility of the proposed method in the interval identification of structural parameters.
Authors:Jianjun Chen; Zhoufang Xiao; Yao Zheng; Jianfeng Zou; Dawei Zhao; Yufeng Yao Pages: 131 - 146 Abstract: Publication date: July 2018 Source:Advances in Engineering Software, Volume 121 Author(s): Jianjun Chen, Zhoufang Xiao, Yao Zheng, Jianfeng Zou, Dawei Zhao, Yufeng Yao A parallel algorithm is proposed for scalable generation of large-scale tetrahedral meshes. The key innovation is the use of a mesh-simplification based domain decomposition approach. This approach works on a background mesh with both its surface and its interior elements much larger than the final elements desired, and decomposes the domain into subdomains containing no undesirable geometric features in the inter-domain interfaces. In this way, the most time-consuming part of domain decomposition can be efficiently parallelized, and other sequential parts consume reasonably limited computing time since they treat a very coarse background mesh. Meanwhile, the subsequent parallel procedures of mesh generation and improvement are most efficient because they can treat individual subdomains without compromising element quality. Compared with published state-of-the-art parallel algorithms, the developed parallel algorithm can reduce the clock time required by the creation of one billion elements on 512 computer cores from roughly half an hour to less than 4 minutes.
Authors:Eric Li; ZC He; G Wang; Yong Jong Pages: 167 - 177 Abstract: Publication date: July 2018 Source:Advances in Engineering Software, Volume 121 Author(s): Eric Li, ZC He, G Wang, Yong Jong Phononic crystals (PCs) have possessed outstanding features to control/manipulate the propagation of the acoustic/sound wave. In this paper, the local resonant elements, such as local resonant cavity in fluid PCs and local resonant inclusion in solid/fluid PCs, are introduced. The effect of geometry parameters, Poisson's ratio, Young's modulus on the band gap solid/fluid PCs are investigated in detail. It is found that wider multiple band gaps are obtained for the fluid PCs with local resonant cavity of “+” hole compared with square and circle holes. More importantly, the very low-frequency band gaps can be obtained by introducing the local resonant inclusion with consideration of fluid-structural interaction for solid/fluid PCs. In addition, we have compared the sound transmission loss in fluid and solid/fluid PCs. The numerical results have clearly indicated that solid/fluids PCs with consideration of fluid-structural interaction can block the propagation of stress wave effectively compared with fluid PCs. The theoretical study and numerical simulation conducted in this work have provided a new avenue to design more innovative fluid and solid/fluid PCs.
Authors:C.H. Silva-Santos; P.R. Goulart; F. Bertelli; A. Garcia; N. Cheung Pages: 178 - 187 Abstract: Publication date: July 2018 Source:Advances in Engineering Software, Volume 121 Author(s): C.H. Silva-Santos, P.R. Goulart, F. Bertelli, A. Garcia, N. Cheung The numerical simulation and optimization in solidification involving geometries beyond one dimension normally requires expensive computational approaches in memory and data processing, generating consequently high cost associated with runtime execution. When boundary conditions are unknown, such as how heat is extracted from the casting surface, which is a typical inverse heat transfer problem (IHTP), the search for such conditions by trial-and-error makes the whole process less feasible. In this sense, this work introduces the application of an artificial immune system (AIS) algorithm as a possible meta-heuristic alternative, with a view to returning acceptable objective values to converge on a set of acceptable solutions. In the present work, the search process of the heat transfer coefficient (hg ) at the casting surface during two-dimensional inward solidification of Al-1.5 wt.%Fe alloy castings of Cartesian and Cylindrical geometries in chilled molds is optimized. Two water-cooled solidification apparatuses were designed to in situ melt the alloy by a set of electrical resistances, in which heat is extracted only through the chilled faces of the molds. The thermal history during solidification was obtained via thermocouples placed at different positions in the castings. A Finite Difference heat transfer model integrated to an optimized version of the artificial immune network algorithm, which uses the experimental thermal profiles as inputs, has been applied to solve the IHTP through the search for acceptable values of heat transfer coefficient. It is shown that fast convergence of the developed algorithm can be achieved for a relatively small number of iterations. The mean relative errors associated with differences between simulated and experimental temperatures are shown to be 1% and 0.07% for Cartesian and Cylindrical geometries, respectively and expressions relating hg to time have been determined for both geometries.
Authors:Ruochen Wang; Qing Ye; Yingfeng Cai; Yong Wang; Xing Xu; Xiangpeng Meng; Chen Long Pages: 188 - 196 Abstract: Publication date: July 2018 Source:Advances in Engineering Software, Volume 121 Author(s): Ruochen Wang, Qing Ye, Yingfeng Cai, Yong Wang, Xing Xu, Xiangpeng Meng, Chen Long In this paper, the influence of interference torques, time delay and noise of automatic steering system (ASS) on trajectory tracking accuracy of intelligent vehicle (IV) is analyzed to further study the coupling mechanism between automatic steering control system and IV trajectory tracking control system. The system architecture of ASS and IV trajectory tracking control system is briefly introduced at first. The correlation controller models are then established based on nonlinear ASS and IV dynamic models. The influence of ASS on the trajectory tracking of IV is validated through simulations with various forms of ASS nonlinear factors. And the results show clearly that the interference torques of ASS have great influence on the accuracy of IV trajectory tracking system, especially in the lateral deviation of IV trajectory tracking system, the noise and time delay of ASS have almost no influence on lateral deviation and azimuth deviation of IV trajectory tracking.
Authors:Fan Yang; Zhufeng Yue; Tian Jian Lu Pages: 197 - 205 Abstract: Publication date: July 2018 Source:Advances in Engineering Software, Volume 121 Author(s): Fan Yang, Zhufeng Yue, Tian Jian Lu The domain decomposition is a conventional approach to compute complex multidisciplinary simulations. The data transfer must be performed on their common interface due to the non-matching meshes for different domains. The adaptive Kriging interpolation method is proposed based on the greedy algorithm. By introducing a learning function, the Kriging interpolation model is constructed by the source grid values. In this way, part of the total source points are selected and the Kriging model is of high precision for the data transfer between the interface. Four examples are investigated to demonstrate the efficiency and accuracy of the proposed method.
Authors:Dmytro Kuksenko; Helmut J. Böhm; Borys Drach Pages: 206 - 222 Abstract: Publication date: July 2018 Source:Advances in Engineering Software, Volume 121 Author(s): Dmytro Kuksenko, Helmut J. Böhm, Borys Drach The large deformation response of composites reinforced by continuous wavy fibers is investigated using three-dimensional Finite Element Analysis. The focus is placed on in-phase fibers with circular cross-sections following sinusoidal paths. The effects of the following micromechanical parameters are analyzed – relative fiber radius, fiber crimp ratio, fiber arrangement and matrix material compressibility. In addition, the responses predicted by three-dimensional and two-dimensional plane strain models are compared. The considered composite is modeled as a fully periodic wavy unit cell subjected to periodic boundary conditions and three load cases – elongations in the x 1 (longitudinal) and x 2 (transverse) directions, and simple shear in the x 1–x 2 plane. Both constituents of the composite, the fibers and the matrix, are modeled using an isotropic hyperelastic material formulation. The results are presented as plots of macroscopic Cauchy stress components versus applied stretch (or strain in the case of the shear loading) and of fiber undulation versus applied stretch for the longitudinal elongation.
Authors:J. Kruis; Y. Tsompanakis; P. Iványi; J. Logo; A. Sextos; B.H.V. Topping Pages: 1 - 3 Abstract: Publication date: June 2018 Source:Advances in Engineering Software, Volume 120 Author(s): J. Kruis, Y. Tsompanakis, P. Iványi, J. Logo, A. Sextos, B.H.V. Topping
Authors:Claudio Floris Pages: 4 - 13 Abstract: Publication date: June 2018 Source:Advances in Engineering Software, Volume 120 Author(s): Claudio Floris This paper is concerned with the stochastic stability of an inverted pendulum with a point mass at the top and a spring at the base; the bar is massless. The base is subjected at the base to a vertical acceleration A(t) that is supposed to be a white noise (delta-correlated) stochastic process. Both Gaussian and Poissonian white noises are considered. A line-like structure excited by a vertical ground motion can be idealized in this way. It is assumed that during the motion the angle of rotation ϑ remains small so that sin ϑ≅ϑ. In this way, the motion equation assumes the classical form of the second order oscillator, but the excitation is parametric so that there is a possibility of stochastic instability. The almost sure (sample) stability and the stability in the second moments are considered herein. It is found that the two stability criteria lead to notable differences in the stability boundaries and the almost sure stability is not conservative. The mean square stability under the Poisson white noise is determined only by the arrival rate of underlying Poisson counting process and by the mean square amplitude of the pulses: the cumulants beyond the second order do not affect it.
Authors:M. Mongelli; I. Roselli; G. De Canio; F. Ambrosino Pages: 14 - 25 Abstract: Publication date: June 2018 Source:Advances in Engineering Software, Volume 120 Author(s): M. Mongelli, I. Roselli, G. De Canio, F. Ambrosino The present paper concerns the implementation of a methodology aiming to achieve a quasi real-time calibration of Finite Element Models (FEMs) of large structural mock-ups during shaking table tests. The damage achieved after each test step is commonly evaluated by visual inspection, since running large numerical analyses or processing the experimental data for damage estimation with common computing resources is very time-consuming and in case of a prolonged stand-by the shaking tables oil temperature stability can be put at risk. On the other hand, the specimen damage level can be monitored through the modal parameters estimated using Finite Element Analyses (FEAs), but FEMs require to be calibrated to provide accountable results. In the proposed approach the FEM calibration was carried out using 3D motion data of a large number of passive markers. They were acquired and processed by a dedicated Displacement Data Processing (DDP) procedure combining the Savitzky-Golay filtering for data noise reduction and the convolution derivation approach for the extraction of the motion parameters. To obtain results in reasonable time between test steps (a few minutes) the methodology exploits the hardware and software resources available on the ENEA High-Performance Computing (HPC) system. Also, the proposed approach allowed to integrate within a single web interface the possibility to share the seismic experiments in real time, while providing updated FEM calibration at each step of the test sequence during the experimental session.
Authors:J. Tezcan; Y. Dak Hazirbaba; Q. Cheng Pages: 26 - 35 Abstract: Publication date: June 2018 Source:Advances in Engineering Software, Volume 120 Author(s): J. Tezcan, Y. Dak Hazirbaba, Q. Cheng This paper presents a semi-parametric mixed-effect regression approach for analyzing and modeling earthquake ground motions, taking into account the correlations between records. Using kernels, the proposed method extends the classical mixed model equations to complicated relationships. The predictive equation is composed of parametric and nonparametric parts. The parametric part incorporates known relationships into the model, while the nonparametric part captures the relationships which cannot be cast into a simple parametric form. A least squares kernel machine is used to infer the nonparametric part of the model. The resulting semi-parametric model combines the strengths of parametric and nonparametric approaches, allowing incorporation of prior, well-justified knowledge into the model while retaining flexibility with respect to the explanatory variables for which the functional form is uncertain. Equations for pointwise confidence and prediction intervals around the conditional mean are provided. The validity of the proposed method is demonstrated through numerical simulations and using recorded ground motions.
Authors:A. Guerine; A. El Hami; L. Walha; T. Fakhfakh; M. Haddar Pages: 45 - 54 Abstract: Publication date: June 2018 Source:Advances in Engineering Software, Volume 120 Author(s): A. Guerine, A. El Hami, L. Walha, T. Fakhfakh, M. Haddar In this paper, we propose a method for taking into account uncertainties based on the projection on polynomial chaos. The proposed method is used to determine the dynamic response of a spur gear system with uncertainty associated to friction coefficient on the teeth contact. We developed a lumped dynamic model with 8dofs. Lagrange formalism is used to formulate the governing equation of motion of the model. The simulation results are obtained by the polynomial chaos method for dynamic analysis under uncertainty. The polynomial chaos results are compared with Monte Carlo simulations.
Authors:Michael S. Jepsen; Lars Damkilde Pages: 55 - 61 Abstract: Publication date: June 2018 Source:Advances in Engineering Software, Volume 120 Author(s): Michael S. Jepsen, Lars Damkilde In the paper a general and direct method for implementation of influence lines in finite element software is provided. Generally influence lines are applied to identify the most critical location and combination of live loads in civil engineering structures. The proposed method is based on the Müller-Breslau principle and the basic idea is to equate discontinuous displacement fields with consistent nodal forces, thus obtaining influence functions only applying a single load case without changing the geometry or boundary conditions of the finite element model. Initially the method is developed by means of some illustrative beam problems, where the consistent nodal forces for angular, lateral and axial displacement discontinuities for a Bernoulli-Euler beam element are derived. Finally it is shown that the method is fully general and efficient in identifying the influence functions of generalized stresses in e.g. plates and shells.
Authors:Masahiro Arai; Yoshitaka Sato; Daisuke Sugiura; Masaomi Nishimura; Hiroaki Ito; Hideo Cho Pages: 62 - 67 Abstract: Publication date: June 2018 Source:Advances in Engineering Software, Volume 120 Author(s): Masahiro Arai, Yoshitaka Sato, Daisuke Sugiura, Masaomi Nishimura, Hiroaki Ito, Hideo Cho In the present paper, the interface fracture toughness between a Ti coating film and Al-alloy substrate is evaluated using a laser spallation method and a boundary element method. The fracture toughness can be estimated using inverse analyses by the boundary element method using a transfer function computed from the history of the displacement of the specimen. In the present study, an alternative boundary element program is developed for unsteady state vibration of an axi-symmetric solid body. The mode I interface fracture toughness between the Ti coating film and Al-alloy substrate is confirmed to be about 0.66 MPam1/2 from the present investigation.
Authors:T. Kudryashova; Yu. Karamzin; V. Podryga; S. Polyakov Pages: 79 - 87 Abstract: Publication date: June 2018 Source:Advances in Engineering Software, Volume 120 Author(s): T. Kudryashova, Yu. Karamzin, V. Podryga, S. Polyakov Gas mixture flows take place in a wide range of scientific and technical problems, including space applications, microchannel streams, nanotechnology and others. This paper deals with numerical simulation of gas mixture flows in microchannels. For such flows speeds can have supersonic, subsonic and transonic ranges according to parameters of gas stream and properties. The supersonic expansion of gas mixtures is accompanied by several simultaneous nonequilibrium processes: interfusion of layers, shock waves, heat exchange with walls etc. To investigate these complex problems, it is essential to develop adequate numerical technique that contains stable and robust numerical algorithms and calculations based on fine grids. These calculations are supposed to be carried out by means of high performance computer systems. This paper presents a new method for simulating gas mixture flows that enables us to solve similar issues and reduce computing time (Garzo et al., 1989; Elizarova, 2009). Particularity of our approach is combination of continuum mechanics and Newton's dynamics models. For computer realization of the approach we use grid methods for solution of macroscopic quasigasdynamic (QGD) equations and molecular dynamics methods (MMD). Some results of numerical modelling are discussed.
Authors:Héctor Migallón; Violeta Migallón; Juan A. Palomino; José Penadés Pages: 88 - 95 Abstract: Publication date: June 2018 Source:Advances in Engineering Software, Volume 120 Author(s): Héctor Migallón, Violeta Migallón, Juan A. Palomino, José Penadés The PageRank algorithm for determining the importance of Web pages has become a central technique in Web search. This algorithm uses the Power method to compute successive iterates that converge to the principal eigenvector of the Markov chain representing the Web link graph. In this work we present an effective heuristic Relaxed and Extrapolated algorithm based on the Power method that accelerates its convergence. A hybrid parallel implementation of this algorithm has been designed by combining various OpenMP threads for each MPI process and several strategies of data distribution among nodes have been analyzed. The results show that the proposed algorithm can significantly speed up the convergence time with respect to the parallel Power algorithm.
Authors:Martin Leitner; David Simunek; Syed Faheem Shah; Michael Stoschka Pages: 96 - 106 Abstract: Publication date: June 2018 Source:Advances in Engineering Software, Volume 120 Author(s): Martin Leitner, David Simunek, Syed Faheem Shah, Michael Stoschka Post-treatment methods enhance the fatigue strength of welded high-strength steel joints significantly. In industrial applications, one commonly applied technique is the high frequency mechanical impact (HFMI) treatment. Attained local benefits increasing fatigue strength are the compressive residual stress state, the reduced notch effect at the weld toe, and additionally the local work hardening of the material. This paper presents the set-up of a closed simulation loop including structural weld simulation, numerical computation of the HFMI-process, and a numerical evaluation of the local fatigue life. A thermo-mechanical coupled weld process simulation using Sysweld is built-up to assess the course of residual stress and strain due to welding. The resulting local material behavior is transferred as mechanical cards to the solver Abaqus for the subsequent numerical simulation of the HFMI-process. Hence, major influences such as transient change of material parameters during welding and subsequent cool-down, effect of process dependent clamping conditions and changing contact characteristics are considered. Finally, a numerical evaluation of the local fatigue behavior by the local stress/strain approach and by crack propagation is performed by the aid of the software packages Femfat, nCode and Franc2D. A comparison of the simulated fatigue life with experimental test results proofs their basic applicability; but also numerical limitations of the presented simulation tools are determined. The major benefit of the established simulation chain is the opportunity to study different weld process and HFMI-treatment parameters in regard to fatigue strength without the need of comparably expensive fatigue tests.
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:T.Q. Ward; W.J. Lewis Abstract: Publication date: August 2018 Source:Advances in Engineering Software, Volume 122 Author(s): T.Q. Li, T. Ward, W.J. Lewis Finite element (FE) analysis produces results, which, in most cases, gain in accuracy, as the size of the FE mesh is reduced. However, this is not necessarily the case when beam and shell element connections induce in-plane torsional effects in the shell. In such situations, shell elements either do not allow for an in-plane torsional stiffness, or, when present, the in-plane torsional stiffness is incorrectly affected by the sizes of the elements. To overcome this problem, we propose a macro- panel element that has fewer degrees of freedom, includes a new model for in-plane torsional stiffness, and produces results with sufficient accuracy to meet engineering requirements. The panel element is based on the principle of sub-structuring, i.e., the panel is meshed internally by smaller shell elements. As shown in the paper, the proposed panel element can be quite large, yet, it can give accurate analysis results. This work helps to overcome a common dilemma in practical use of finite element analysis, where finite element theory requires element sizes to be sufficiently small, but practical considerations suggest the use of large-size elements that simplify the modelling process and reduce excesses in generated results. A model built using macro-panel elements is equivalent to the model built using smaller shell elements, with the normal and shear stresses in the former being the same as the stresses in the finely meshed shell element model, We identify a number of performance benefits that become available as a consequence of modelling the shell elements at a higher level of abstraction.
Authors:Jan Piotr Abstract: Publication date: August 2018 Source:Advances in Engineering Software, Volume 122 Author(s): Jan Jaśkowiec, Piotr Pluciński The aim of the paper is the development of discontinuous Galerkin with finite difference rules (DGFD) to a two-dimensional stationary and non-stationary thermoelasticity problem. Displacement and temperature fields are approximated on the same mesh frame but with various approximation orders, which are set independently for each of the fields. Because the DGFD method does not use nodes, special attention needs to be paid to applying boundary conditions. Various types of thermal and mechanical boundary conditions are considered. In the presented approach only one stabilization parameter for the coupled problem needs to be evaluated in the DGFD method. The same parameter used in thermal and in mechanical part. The considered domain is discretized by a polygonal mesh in which the polygonal elements may have arbitrary shapes, such as e.g. a fish shape, as well as typical rectangular shapes. The orthogonality of Chebyshev basis functions may be utilized for rectangular elements. Very high-order approximate solution can be obtained in such case. In the coupled problem, the same element may be high-order for displacement field while low-order to approximate temperature. The argument contained in the paper is illustrated with few examples.
Authors:Yin-Fu JIN; Zhen-Yu YIN Abstract: Publication date: July 2018 Source:Advances in Engineering Software, Volume 121 Author(s): Yin-Fu JIN, Zhen-Yu YIN The focus of this paper is ErosLab, a useful tool for the development, analysis and application of constitutive models developed to solve the modelling problems inherent in soil tests. The ErosLab is programmed in the way of admixture programming with C#, MATLAB and FORTRAN, offering a powerful environment for various kinds of modelling soil tests. The proposed tool has six important features: (1) a mechanical calculator; (2) the ability to cover various kinds of soil tests; (3) a number of soil models with a user extension interface; (4) multiple methods of loading control; (5) comprehensive and efficient debugging; and (6) visualisation with graphical displays. Furthermore, the entire graphical user interface and usage instructions for the tool are briefly illustrated in simple and practical terms. Finally, three case studies are presented in which ErosLab was used, to highlight its performance in modelling tests for different soils.
Authors:Xingxing Feng; Yunqing Zhang Jinglai Abstract: Publication date: July 2018 Source:Advances in Engineering Software, Volume 121 Author(s): Xingxing Feng, Yunqing Zhang, Jinglai Wu An interval analysis method termed as Legendre interval model is presented to solve multibody dynamic systems with interval parameters. The implementation of Legendre interval model involves two steps. The first step is to approximate the original multibody model using Legendre polynomial approximation. Then take the interval parameters into consideration, and the Legendre interval model with interval parameters is obtained. The second step is to calculate the bounds of Legendre interval model using interval arithmetic or scanning. Legendre interval model using interval arithmetic, Legendre interval model using scanning, Chebyshev inclusion function method and scanning method are applied into typical multibody systems with interval parameters and compared in terms of efficiency and accuracy. The Legendre interval model using scanning shows high accuracy and efficiency.
Authors:Kosec Abstract: Publication date: June 2018 Source:Advances in Engineering Software, Volume 120 Author(s): G. Kosec This paper deals with a numerical solution of an incompressible Navier-Stokes flow on non-uniform domains. The numerical solution procedure comprises the Meshless Local Strong Form Method for spatial discretization, explicit time stepping, local pressure-velocity coupling and an algorithm for positioning of computational nodes inspired by Smoothed Particles Hydrodynamics method. The presented numerical approach is demonstrated by solving a lid driven cavity flow and backward facing step problems, first on regular nodal distributions up to 315,844 (562×562) nodes and then on domain filled with randomly generated obstacles. It is demonstrated that the presented solution procedure is accurate, stable, convergent, and it can effectively solve the fluid flow problem on complex geometries. The results are presented in terms of velocity profiles, convergence plots, and stability analyses.
Abstract: Publication date: June 2018 Source:Advances in Engineering Software, Volume 120 Author(s): A. Csébfalvi In this paper, using a recently developed unified approach, benchmark results are presented for structural optimization when the only source of uncertainty is the variability of the applied load directions. The worst-load-direction oriented framework can be applied to a broad class of engineering optimization problems. In each case, the central element of the solution searching algorithm is a standard multi-load structure optimization problem, which using an appropriate method, can be solved within reasonable time. The varying load directions are handled by additional linear or nonlinear relations, which describe the allowable perturbations of the nominal load directions. The result of the optimization is a performance measure minimal design which is invariant to the investigated uncertainty type and satisfies the response constraints. In order to illustrate the viability and efficiency of the approach, problem-specific models, algorithms and detailed benchmark results are presented for volume minimization of 2D continuum structures with compliance constraints and weight minimization of 2D truss structures with displacement and stress constraints. In each case, the computational cost of the proposed approach is comparable with its fixed load direction oriented equivalent because the worst-load-direction identification process is searching on the space of allowable direction perturbations, which generally means an easier and smaller computational problem than the standard multi-load structure optimization.
Authors:Huan Qin; Yi Guo; Zijian Liu; Yu Liu; Haolong Zhong Abstract: Publication date: Available online 6 April 2018 Source:Advances in Engineering Software Author(s): Huan Qin, Yi Guo, Zijian Liu, Yu Liu, Haolong Zhong At conceptual design stage, the cross-sectional shape design of automotive body-in-white (BIW) frame is a critical and intractable technique. This paper presents shape optimization using an improved genetic algorithm (GA) optimizer to promote the development of auto-body. The shape optimization problem is formulated as a mass minimization problem with static stiffness, dynamic eigenfrequency and manufacture constraints. Then the transfer stiffness matrix method (TSMM) proposed in our previous study is adopted for the exact static and dynamic analyses of BIW frame. Additionally, the scale vector method is introduced to remarkably reduce design variables. Especially, an integrated object-oriented GA optimizer, which employs penalty-parameterless approach to handle constraints, is developed to solve constrained single-objective and multi-objective optimization problems. The optimizer is benchmarked on 12 test functions and compared with a variety of current metaheuristic algorithms to demonstrate its validity and effectiveness. Lastly, the optimizer is applied to the solution of BIW shape optimization.
Authors:Kai Li; Yanyun Yu; Yunlong Wang; Zhenwu Hu Abstract: Publication date: Available online 5 April 2018 Source:Advances in Engineering Software Author(s): Kai Li, Yanyun Yu, Yunlong Wang, Zhenwu Hu Due to the increase of the operating cost and material cost, weight reduction has attracted much attention among ship designers and ship owners. Ship structure optimization remains a very complicated problem due to the feasible combinations of structural members with different sections are numerous. In the present work, based on artificial bee colony (ABC) algorithm, we propose a structural design optimization method of fiber reinforced plastic (FRP) ship structure. The objective of the proposed optimization method is to minimize the weight of FRP ship structure under a group of constraints. In order to deal with parametric finite element analysis (FEA) of the whole FRP ship structure, the modeling work is simplified by using beam element instead of shell element to simulate top hat stiffener. To evaluate the applicability of the proposed method, it was applied to a problem for finding optimal structure of a 32.98 m FRP fishing vessel. The result shows that the developed program can decrease the structural weight by about 8.31%. Thus, this study will be able to contribute to make energy saving and environment-friendly ship.
Authors:Pablo Gonzalez-de-Aledo; Andrey Vladimirov; Marco Manca; Jerry Baugh; Ryo Asai; Marcus Kaiser; Roman Bauer Abstract: Publication date: Available online 5 April 2018 Source:Advances in Engineering Software Author(s): Pablo Gonzalez-de-Aledo, Andrey Vladimirov, Marco Manca, Jerry Baugh, Ryo Asai, Marcus Kaiser, Roman Bauer Current research in the field of computational biology often involves simulations on high-performance computer clusters. It is crucial that the code of such simulations is efficient and correctly reflects the model specifications. In this paper, we present an optimization strategy for agent-based simulations of biological dynamics using Intel Xeon Phi coprocessors, demonstrated by a prize-winning entry of the “Intel Modern Code Developer Challenge” competition. These optimizations allow simulating various biological mechanisms, in particular the simulation of millions of cells, their proliferation, movements and interactions in 3D space. Overall, our results demonstrate a powerful approach to implement and conduct very detailed and large-scale computational simulations for biological research. We also highlight the main difficulties faced when developing such optimizations, in particular the assessment of the simulation accuracy, the dependencies between different optimization techniques and counter-intuitive effects in the speed of the optimized solution. The overall speedup of 595 × shows a good parallel scalability.
Abstract: Publication date: Available online 1 March 2018 Source:Advances in Engineering Software Author(s): A. Csébfalvi, J. Lógó Uncertainty is an important consideration in topology optimization to produce robust and reliable solutions. There are several possibilities to take into account the uncertainty in the topology optimization of continuum structures. In this paper, we assume that the only source of uncertainty is the variability of the applied load directions. Most models in this area apply parametric statistical tools to describe the directional uncertainty of the applied loads to produce robust structures which are insensitive to the directional uncertainty as much as possible. In the most popular parametric statistical approach the expected-compliance, based on the directional normality assumption, is used as the preferred measure of robustness. We will proof indirectly that this approach is far from the engineering practice and may give hardly interpretable or totally misleading results, which will be demonstrated by two carefully selected counter-examples. The counter-examples validate the fact that the expected-compliance, as a statistical abstraction based on more or less theoretical assumption about normality, not a general applicable measure of robustness. It will be shown, that the non-parametric and really robust volume-constrained worst-load-direction-oriented minimax-compliance model, used in this paper only as a proofing tool in a very simple form, is a viable alternative of the parametric expected-compliance model and its results and its problem solving process as a whole are very close to the engineering thinking. The worst-load-direction-oriented minimax-compliance-model provides expressive, rigorous, generally applicable, and objective information about the robustness. The parametric expected-compliance in itself as the preferred measure of robustness is unable to characterize the compliance variability, in contrast of the minimax approach which can be describe the compliance variability by a robust range-like measure computed very easily as the difference of the maximal- and minimal-compliance on the set of the feasible loading directions.
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