Pub Date : 2024-11-02DOI: 10.1016/j.compstruc.2024.107566
Yongtao Bai , Chen Chen , Yao Chen , Ruining Zhu
The exigencies of intricate environments necessitate the conception of structures exhibiting extraordinary performance. In response, we devised a foldable modular origami structure by combining Miura-Origami and perforated plates, employing a novel design strategy. We substantiated that this structure manifests adjustable Poisson’s ratios in diverse directions, spanning from negative values to positive, and can even approach infinity. While singular modular origami structures demonstrate inferior performance compared to periodic configurations, our focus has shifted to a more comprehensive analysis. Therefore, we conducted finite element analyses to scrutinize the mechanical behavior of periodically arranged modular origami structures. Remarkably, the same structure can exhibit either analogous or entirely disparate mechanical properties in distinct folding states. The inherent variability in Poisson’s ratio and mechanical performance opens new possibilities for applications in prospective complex environments, such as unfolding thin-walled structures, structural load-bearing, energy absorption, and so forth.
{"title":"A novel modular origami strategy: Achieving adjustable Poisson’s ratio and tunable distinctive mechanical properties for versatile applications","authors":"Yongtao Bai , Chen Chen , Yao Chen , Ruining Zhu","doi":"10.1016/j.compstruc.2024.107566","DOIUrl":"10.1016/j.compstruc.2024.107566","url":null,"abstract":"<div><div>The exigencies of intricate environments necessitate the conception of structures exhibiting extraordinary performance. In response, we devised a foldable modular origami structure by combining Miura-Origami and perforated plates, employing a novel design strategy. We substantiated that this structure manifests adjustable Poisson’s ratios in diverse directions, spanning from negative values to positive, and can even approach infinity. While singular modular origami structures demonstrate inferior performance compared to periodic configurations, our focus has shifted to a more comprehensive analysis. Therefore, we conducted finite element analyses to scrutinize the mechanical behavior of periodically arranged modular origami structures. Remarkably, the same structure can exhibit either analogous or entirely disparate mechanical properties in distinct folding states. The inherent variability in Poisson’s ratio and mechanical performance opens new possibilities for applications in prospective complex environments, such as unfolding thin-walled structures, structural load-bearing, energy absorption, and so forth.</div></div>","PeriodicalId":50626,"journal":{"name":"Computers & Structures","volume":"305 ","pages":"Article 107566"},"PeriodicalIF":4.4,"publicationDate":"2024-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142573315","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-02DOI: 10.1016/j.compstruc.2024.107577
Wei Cheng , Xiaopeng Zhang , Tiannan Hu , Jing Li , Yaguang Wang
This paper proposes a stress-constrained structural topology optimization method in the velocity field level set framework. To avoid the strength failure in structures, the stress should meet certain strength criteria at all material points. This point-wise constraint brings great difficulty to topology optimization. Instead of using the traditional aggregation scheme, we propose a new stress constraint in the single domain integral form, which is mathematically equivalent to the point-wise stress limitation and enables the precise stress control throughout the entire material domain without introducing numerous constraints. Its simple expression with relatively low non-linearity facilitates the optimization formulation, the sensitivity analysis and the numerical implementation. Here, the velocity field level set method is used for the stress-constraint topology optimization. The implicit material representation by the level set model is combined with the body-fitted mesh, which provides a clear and smooth material boundary with high numerical calculation accuracy for the stress and the sensitivity. Moreover, the velocity field level set method maps the original boundary variation-based optimization problem from the functional design space into a finite-dimensional one by introducing the velocity field design variables. Thus, it allows using of the general mathematical optimization algorithms in the level set model, which provides an efficient and steady way to deal with the stress-constrained optimization problems.
{"title":"Stress-constrained topology optimization using the velocity field level set method","authors":"Wei Cheng , Xiaopeng Zhang , Tiannan Hu , Jing Li , Yaguang Wang","doi":"10.1016/j.compstruc.2024.107577","DOIUrl":"10.1016/j.compstruc.2024.107577","url":null,"abstract":"<div><div>This paper proposes a stress-constrained structural topology optimization method in the velocity field level set framework. To avoid the strength failure in structures, the stress should meet certain strength criteria at all material points. This point-wise constraint brings great difficulty to topology optimization. Instead of using the traditional aggregation scheme, we propose a new stress constraint in the single domain integral form, which is mathematically equivalent to the point-wise stress limitation and enables the precise stress control throughout the entire material domain without introducing numerous constraints. Its simple expression with relatively low non-linearity facilitates the optimization formulation, the sensitivity analysis and the numerical implementation. Here, the velocity field level set method is used for the stress-constraint topology optimization. The implicit material representation by the level set model is combined with the body-fitted mesh, which provides a clear and smooth material boundary with high numerical calculation accuracy for the stress and the sensitivity. Moreover, the velocity field level set method maps the original boundary variation-based optimization problem from the functional design space into a finite-dimensional one by introducing the velocity field design variables. Thus, it allows using of the general mathematical optimization algorithms in the level set model, which provides an efficient and steady way to deal with the stress-constrained optimization problems.</div></div>","PeriodicalId":50626,"journal":{"name":"Computers & Structures","volume":"305 ","pages":"Article 107577"},"PeriodicalIF":4.4,"publicationDate":"2024-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142573316","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-31DOI: 10.1016/j.compstruc.2024.107562
Thanh N. Huynh, Jaehong Lee
This article introduces an extension to the Optimal Thickness Prediction (OTP) approach for solving the hybrid material composite laminate blending optimization problem considering both Buckling Factor and Failure Index constraints. The proposed optimization approach solves the blending optimization problem with a two-stage procedure. The Stacking Sequence of the laminate is first optimized using optimization algorithms, and then utilized as the input for the CNN-based prediction model to predict the corresponding optimal regional thickness. The present extended approach expands the dimension capacity of the OTP model by including an additional laminate material input dimension and Failure Index output dimension. The additional features broaden the scope of the OTP model to simultaneously handle more design variables and constraints. An integration of the proposed approach with a lamination guideline-based Genetic Algorithm is presented. A hybrid material variation of the 18-panel horseshoe blending optimization problem is introduced and utilized for demonstration of the effectiveness of the proposed approach. The obtained result highlights the significant improvement in performance of the integrated method over the base algorithm.
{"title":"Optimal thickness distribution design for blending hybrid composite laminates using Buckling Factor and Failure Index prediction","authors":"Thanh N. Huynh, Jaehong Lee","doi":"10.1016/j.compstruc.2024.107562","DOIUrl":"10.1016/j.compstruc.2024.107562","url":null,"abstract":"<div><div>This article introduces an extension to the Optimal Thickness Prediction (OTP) approach for solving the hybrid material composite laminate blending optimization problem considering both Buckling Factor and Failure Index constraints. The proposed optimization approach solves the blending optimization problem with a two-stage procedure. The Stacking Sequence of the laminate is first optimized using optimization algorithms, and then utilized as the input for the CNN-based prediction model to predict the corresponding optimal regional thickness. The present extended approach expands the dimension capacity of the OTP model by including an additional laminate material input dimension and Failure Index output dimension. The additional features broaden the scope of the OTP model to simultaneously handle more design variables and constraints. An integration of the proposed approach with a lamination guideline-based Genetic Algorithm is presented. A hybrid material variation of the 18-panel horseshoe blending optimization problem is introduced and utilized for demonstration of the effectiveness of the proposed approach. The obtained result highlights the significant improvement in performance of the integrated method over the base algorithm.</div></div>","PeriodicalId":50626,"journal":{"name":"Computers & Structures","volume":"305 ","pages":"Article 107562"},"PeriodicalIF":4.4,"publicationDate":"2024-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142554134","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-31DOI: 10.1016/j.compstruc.2024.107574
Da Shi , Cristoforo Demartino , Giuseppe Carlo Marano , Yongjia Xu
The performance of glue laminated bamboo (glubam) members is governed by the nonlinear response at their joints, where high deformation levels and stress concentrations are developed. Numerous phenomenological models are presently employed to describe the hysteresis behavior of these joints, while these models always have an excessive number of parameters, and the physical interpretation of these parameters is often challenging. Moreover, some hysteresis models cannot capture all hysteresis features such as asymmetry, pinching, and damage. Consequently, this paper introduces a novel phenomenological-based hysteretic model named Asymmetric Pinching Damaged (APD) model, and implemented it in Abaqus by combining connector and spring elements in series or parallel. This model encompasses asymmetry, pinching, and strength degradation for bamboo joint components, with parameters that possess clear physical meanings and are readily comprehensible. This study also presented a parameter identification framework coupling the Parallel Genetic Algorithm (PGA) and Bayesian Neural Network (BNN). By merging the FE modeling and optimizing algorithms with the interactive application of ABAQUS and Python software platforms, the integrated identification framework is capable of performing multi-threaded parallel computation of finite element models considering the BNN-based uncertainty quantification, thus greatly improving the efficiency of parameter identification.
{"title":"An asymmetric pinching damaged hysteresis model for glubam members: Parameter identification and model comparison","authors":"Da Shi , Cristoforo Demartino , Giuseppe Carlo Marano , Yongjia Xu","doi":"10.1016/j.compstruc.2024.107574","DOIUrl":"10.1016/j.compstruc.2024.107574","url":null,"abstract":"<div><div>The performance of glue laminated bamboo (glubam) members is governed by the nonlinear response at their joints, where high deformation levels and stress concentrations are developed. Numerous phenomenological models are presently employed to describe the hysteresis behavior of these joints, while these models always have an excessive number of parameters, and the physical interpretation of these parameters is often challenging. Moreover, some hysteresis models cannot capture all hysteresis features such as asymmetry, pinching, and damage. Consequently, this paper introduces a novel phenomenological-based hysteretic model named Asymmetric Pinching Damaged (APD) model, and implemented it in Abaqus by combining connector and spring elements in series or parallel. This model encompasses asymmetry, pinching, and strength degradation for bamboo joint components, with parameters that possess clear physical meanings and are readily comprehensible. This study also presented a parameter identification framework coupling the Parallel Genetic Algorithm (PGA) and Bayesian Neural Network (BNN). By merging the FE modeling and optimizing algorithms with the interactive application of ABAQUS and Python software platforms, the integrated identification framework is capable of performing multi-threaded parallel computation of finite element models considering the BNN-based uncertainty quantification, thus greatly improving the efficiency of parameter identification.</div></div>","PeriodicalId":50626,"journal":{"name":"Computers & Structures","volume":"305 ","pages":"Article 107574"},"PeriodicalIF":4.4,"publicationDate":"2024-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142560589","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-31DOI: 10.1016/j.compstruc.2024.107568
Yuan Yong , Sang Qiaozhi , Chen Xi
The idea of Phase Field Method (PFM) is introduced to depict the dynamic shear modulus degradation of saturated soil revealed in the undrained triaxial tests. The order parameter in PFM is adopted to govern the liquefaction process. Then the inherent and generalized constitutive relation among shear stress, shear strain, shear modulus and confining pressure is derived. It more complies to thermodynamics in comparison to conventional empirical model following a phenomenological description. By comparing to existed empirical model, the presented four-parameter model is validated to be of robustness and efficacy to various soil types and confining pressure levels under monotonic and cyclic loading. The simulated pore pressure varies simultaneously with modulus degradation, which is consistent with observations and energy consideration. The presented method makes it possible to apply to deformation prediction in deep excavation and other engineering practice, whilst without loss of physical interpretations.
{"title":"Dynamic shear modulus degradation of saturated soil analysis: From the perspective of phase field theory","authors":"Yuan Yong , Sang Qiaozhi , Chen Xi","doi":"10.1016/j.compstruc.2024.107568","DOIUrl":"10.1016/j.compstruc.2024.107568","url":null,"abstract":"<div><div>The idea of Phase Field Method (PFM) is introduced to depict the dynamic shear modulus degradation of saturated soil revealed in the undrained triaxial tests. The order parameter in PFM is adopted to govern the liquefaction process. Then the inherent and generalized constitutive relation among shear stress, shear strain, shear modulus and confining pressure is derived. It more complies to thermodynamics in comparison to conventional empirical model following a phenomenological description. By comparing to existed empirical model, the presented four-parameter model is validated to be of robustness and efficacy to various soil types and confining pressure levels under monotonic and cyclic loading. The simulated pore pressure varies simultaneously with modulus degradation, which is consistent with observations and energy consideration. The presented method makes it possible to apply to deformation prediction in deep excavation and other engineering practice, whilst without loss of physical interpretations.</div></div>","PeriodicalId":50626,"journal":{"name":"Computers & Structures","volume":"305 ","pages":"Article 107568"},"PeriodicalIF":4.4,"publicationDate":"2024-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142560588","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-30DOI: 10.1016/j.compstruc.2024.107571
L. Greco, D. Castello, M. Cuomo
An implicit formulation for cylindrical joints (pivots) connecting slender rods in large deformations is presented exploiting the G1 map at the beam's end. The rotation at the end of the rod is decomposed in the rotation of the pivot axis and a rotation around this axis. A mixed variational formulation that uses the spherical linear interpolation for the rotations is implemented. It allows to effectively model both rigid and elastic mechanisms. The proposed formulation is applied to several examples ranging from spherical scissor mechanism to elastic deployable structures that exploit the onset of instability for achieving the target shape.
{"title":"An objective minimal constraint formulation for the analysis of elastic articulated structures","authors":"L. Greco, D. Castello, M. Cuomo","doi":"10.1016/j.compstruc.2024.107571","DOIUrl":"10.1016/j.compstruc.2024.107571","url":null,"abstract":"<div><div>An implicit formulation for cylindrical joints (pivots) connecting slender rods in large deformations is presented exploiting the G<sup>1</sup> map at the beam's end. The rotation at the end of the rod is decomposed in the rotation of the pivot axis and a rotation around this axis. A mixed variational formulation that uses the spherical linear interpolation for the rotations is implemented. It allows to effectively model both rigid and elastic mechanisms. The proposed formulation is applied to several examples ranging from spherical scissor mechanism to elastic deployable structures that exploit the onset of instability for achieving the target shape.</div></div>","PeriodicalId":50626,"journal":{"name":"Computers & Structures","volume":"305 ","pages":"Article 107571"},"PeriodicalIF":4.4,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142554131","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-30DOI: 10.1016/j.compstruc.2024.107572
Han Fei , Wu Lei , Li Shiyang , Deng Zichen , Wu Fa
Aiming at the reanalysis problem of time-varying eigenvalues of force-shape coupled systems, this paper proposes an energy-preserving matrix perturbation theory (EPMPT) that can maintain the essential physical properties of the system. The classical matrix perturbation method, which employs interpolated shape functions, fails to evaluate and address solution errors promptly during the continuous perturbation process. This limitation has led to the theoretical issue of “eigenvalue drift”, a flaw that has persisted in the original method since its introduction 40 years ago. In contrast, the presented method uses the dynamic stiffness method to obtain the system eigenvalues and eigenvectors at one time, and provides a perturbation solution to the time-varying eigenvalue problem. Further combined with the J count test technology in the Wittrick-Williams algorithm, an energy-preserving method that can “self-check and self-correct” the solution was developed. The idea that “continuous perturbation should maintain force-shape dynamic self-consistency in the frequency domain” is proposed, and avoiding the energy dispersion and resulting distortion problems caused by long-term numerical simulation. To illustrate the advantage of the EPMPT, a thermally induced vibration of an aerospace structure including force-shape coupling effect, and the vibration of a flexible space solar power arrays including rigid-flexible coupling effect are investigated. Case studied elucidates that EPMPT possesses the capability to notably enhance the computational efficiency associated with generalized eigenvalue and response reanalysis problems. When juxtaposed against conventional step-by-step integration methods, EPMPT has been found to augment computational efficiency by a margin of at least 70 %, and in some instances, up to 90 %.
{"title":"Energy-preserving matrix perturbation theory for coupling dynamic analysis of flexible structures","authors":"Han Fei , Wu Lei , Li Shiyang , Deng Zichen , Wu Fa","doi":"10.1016/j.compstruc.2024.107572","DOIUrl":"10.1016/j.compstruc.2024.107572","url":null,"abstract":"<div><div>Aiming at the reanalysis problem of time-varying eigenvalues of force-shape coupled systems, this paper proposes an energy-preserving matrix perturbation theory (EPMPT) that can maintain the essential physical properties of the system. The classical matrix perturbation method, which employs interpolated shape functions, fails to evaluate and address solution errors promptly during the continuous perturbation process. This limitation has led to the theoretical issue of “eigenvalue drift”, a flaw that has persisted in the original method since its introduction 40 years ago. In contrast, the presented method uses the dynamic stiffness method to obtain the system eigenvalues and eigenvectors at one time, and provides a perturbation solution to the time-varying eigenvalue problem. Further combined with the <em>J</em> count test technology in the Wittrick-Williams algorithm, an energy-preserving method that can “self-check and self-correct” the solution was developed. The idea that “continuous perturbation should maintain force-shape dynamic self-consistency in the frequency domain” is proposed, and avoiding the energy dispersion and resulting distortion problems caused by long-term numerical simulation. To illustrate the advantage of the EPMPT, a thermally induced vibration of an aerospace structure including force-shape coupling effect, and the vibration of a flexible space solar power arrays including rigid-flexible coupling effect are investigated. Case studied elucidates that EPMPT possesses the capability to notably enhance the computational efficiency associated with generalized eigenvalue and response reanalysis problems. When juxtaposed against conventional step-by-step integration methods, EPMPT has been found to augment computational efficiency by a margin of at least 70 %, and in some instances, up to 90 %.</div></div>","PeriodicalId":50626,"journal":{"name":"Computers & Structures","volume":"305 ","pages":"Article 107572"},"PeriodicalIF":4.4,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142554132","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-30DOI: 10.1016/j.compstruc.2024.107567
Qingquan Wang, Carlos Pantano
While numerical physical models of contact mechanics have become increasingly prevalent, the implementation of these models to efficiently resolve geometric contact with a robust contact search strategy remains lacking. Our research endeavors to address this gap by introducing a comprehensive solution with an exact geometric contact mechanics algorithm for thin shell finite elements with an explicit time scheme. The method has several key features, including precise geometrical resolution of self-contact interactions enabled by a sub-time-step marching method, adaptive data structures to minimize computational overhead, and a dedicated parallelization implementation with load-balancing capability. An efficient detection algorithm is implemented to reduce the natural polynomial time complexity of the problem by decomposing it into two phases: global and local phase contact detection. The impact equations are then applied to resolve the contact event by enforcing the conservation of kinematic energy and momentum. This contact algorithm is fully integrated with the MPI-based parallelization of the thin-shell finite element solver to ensure even load-balancing. The robustness and correctness of the algorithm is demonstrated in three numerical studies. Additionally, a strong scaling study showcases the scalability of the parallelization associated with the algorithm.
{"title":"A parallel geometric contact algorithm for thin shell finite elements in explicit time integration","authors":"Qingquan Wang, Carlos Pantano","doi":"10.1016/j.compstruc.2024.107567","DOIUrl":"10.1016/j.compstruc.2024.107567","url":null,"abstract":"<div><div>While numerical physical models of contact mechanics have become increasingly prevalent, the implementation of these models to efficiently resolve geometric contact with a robust contact search strategy remains lacking. Our research endeavors to address this gap by introducing a comprehensive solution with an exact geometric contact mechanics algorithm for thin shell finite elements with an explicit time scheme. The method has several key features, including precise geometrical resolution of self-contact interactions enabled by a sub-time-step marching method, adaptive data structures to minimize computational overhead, and a dedicated parallelization implementation with load-balancing capability. An efficient detection algorithm is implemented to reduce the natural polynomial time complexity of the problem by decomposing it into two phases: global and local phase contact detection. The impact equations are then applied to resolve the contact event by enforcing the conservation of kinematic energy and momentum. This contact algorithm is fully integrated with the MPI-based parallelization of the thin-shell finite element solver to ensure even load-balancing. The robustness and correctness of the algorithm is demonstrated in three numerical studies. Additionally, a strong scaling study showcases the scalability of the parallelization associated with the algorithm.</div></div>","PeriodicalId":50626,"journal":{"name":"Computers & Structures","volume":"305 ","pages":"Article 107567"},"PeriodicalIF":4.4,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142554133","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-28DOI: 10.1016/j.compstruc.2024.107576
Han-xu Zou, Wen-ming Zhang, Yu-peng Chen
This study addresses the stability problem of long-span cable-supported bridges (CSBs) under live loads, which requires an accurate estimation of maximum girder deflection and rotation angle. In contrast to the cumbersome influence line method or analytical method, which ignores the structural nonlinearity of this bridge type or uses too many constraint conditions, we convert this problem into an optimization task. Since the number of segments of distributed live loads under which maximum girder deflection and rotation angle occur (i.e., the number of optimization variables) is unknown due to CSB’s structural complexity, a multi-population competition genetic algorithm (MPCGA), inspired by the population competition theory in ecology, is applied. It incorporates the Lotka-Volterra competition model to depict the changing sizes of the competing populations. We designed the interspecies migration and exchange mechanism for the above engineering problem and ran ANSYS to compute individual fitness. This algorithm offers high accuracy and efficiency in solving the maximum girder deflection and rotation angle of the long-span CSB, the positions where the maximum girder deflection and rotation angle occur, and the corresponding live load patterns. Finally, the proposed method is validated by a case study of a hybrid CSB with a main span of 1400 m. The calculation results obtained via the conventional influence line and proposed methods are compared, proving the latter’s supremacy.
{"title":"Multi-population competition genetic algorithm for assessing long-span cable-supported bridge girder’s maximum deflections and rotation angles under live loads: A direct optimization task solution","authors":"Han-xu Zou, Wen-ming Zhang, Yu-peng Chen","doi":"10.1016/j.compstruc.2024.107576","DOIUrl":"10.1016/j.compstruc.2024.107576","url":null,"abstract":"<div><div>This study addresses the stability problem of long-span cable-supported bridges (CSBs) under live loads, which requires an accurate estimation of maximum girder deflection and rotation angle. In contrast to the cumbersome influence line method or analytical method, which ignores the structural nonlinearity of this bridge type or uses too many constraint conditions, we convert this problem into an optimization task. Since the number of segments of distributed live loads under which maximum girder deflection and rotation angle occur (i.e., the number of optimization variables) is unknown due to CSB’s structural complexity, a multi-population competition genetic algorithm (MPCGA), inspired by the population competition theory in ecology, is applied. It incorporates the Lotka-Volterra competition model to depict the changing sizes of the competing populations. We designed the interspecies migration and exchange mechanism for the above engineering problem and ran ANSYS to compute individual fitness. This algorithm offers high accuracy and efficiency in solving the maximum girder deflection and rotation angle of the long-span CSB, the positions where the maximum girder deflection and rotation angle occur, and the corresponding live load patterns. Finally, the proposed method is validated by a case study of a hybrid CSB with a main span of 1400 m. The calculation results obtained via the conventional influence line and proposed methods are compared, proving the latter’s supremacy.</div></div>","PeriodicalId":50626,"journal":{"name":"Computers & Structures","volume":"305 ","pages":"Article 107576"},"PeriodicalIF":4.4,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142530132","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-25DOI: 10.1016/j.compstruc.2024.107569
Xiang Xie , Haijun Wu , Steffen Marburg
In many engineering applications, the solution of acoustic wave problems in the infinite domain is required over a broad frequency range with densely sampled increments. In order to achieve efficient numerical simulations via a spatial discretization, e.g. finite element method, additional artificial absorbing boundaries are necessary to truncate the computational domain into appropriate bounded sizes. One of the most commonly used non-reflecting techniques to attenuate propagating waves is known as the perfectly matched layer. However, the system matrices arising from the finite element treatment of the Helmholtz equation in the absorbing layers are frequency-dependent, implying that they must be formed and inverted at each frequency of interest. Such a procedure is rather troublesome for frequency sweeps. To address this, a surrogate of perfectly matched layers is proposed, which enables the corresponding system matrices to be independent of the frequency. Moreover, it avoids the use of a relatively large computational domain and relatively thick enclosed layers at low frequencies, thus improving the ability of perfectly matched layers across the entire frequency range. After that, an adaptive projection-based model order reduction scheme is further developed to reduce the computational complexity of exterior acoustic systems. A robust error indicator based on the relative error of two constructed reduced order models is accordingly introduced. The performance of the present solution framework is discussed and compared with other implementation strategies, in the context of multi-frequency solution of two-dimensional test models with single or multiple scatterers.
{"title":"A frequency-independent absorption function surrogate for perfectly matched layer in exterior acoustics","authors":"Xiang Xie , Haijun Wu , Steffen Marburg","doi":"10.1016/j.compstruc.2024.107569","DOIUrl":"10.1016/j.compstruc.2024.107569","url":null,"abstract":"<div><div>In many engineering applications, the solution of acoustic wave problems in the infinite domain is required over a broad frequency range with densely sampled increments. In order to achieve efficient numerical simulations via a spatial discretization, <em>e.g.</em> finite element method, additional artificial absorbing boundaries are necessary to truncate the computational domain into appropriate bounded sizes. One of the most commonly used non-reflecting techniques to attenuate propagating waves is known as the perfectly matched layer. However, the system matrices arising from the finite element treatment of the Helmholtz equation in the absorbing layers are frequency-dependent, implying that they must be formed and inverted at each frequency of interest. Such a procedure is rather troublesome for frequency sweeps. To address this, a surrogate of perfectly matched layers is proposed, which enables the corresponding system matrices to be independent of the frequency. Moreover, it avoids the use of a relatively large computational domain and relatively thick enclosed layers at low frequencies, thus improving the ability of perfectly matched layers across the entire frequency range. After that, an adaptive projection-based model order reduction scheme is further developed to reduce the computational complexity of exterior acoustic systems. A robust error indicator based on the relative error of two constructed reduced order models is accordingly introduced. The performance of the present solution framework is discussed and compared with other implementation strategies, in the context of multi-frequency solution of two-dimensional test models with single or multiple scatterers.</div></div>","PeriodicalId":50626,"journal":{"name":"Computers & Structures","volume":"305 ","pages":"Article 107569"},"PeriodicalIF":4.4,"publicationDate":"2024-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142530131","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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