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Subpicosecond laser ablation behavior of a magnesium target and crater evolution:Molecular dynamics study and experimental validation

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Chinese Physics B 2024年第7期33卷 613-622页

作者：江国龙周霞 State Key Laboratory of Structural Analysis for Industrial Equipment Department of Engineering MechanicsFaculty of Vehicle Engineering and MechanicsDalian University of TechnologyDalian 116024China

The micro-ablation processes and morphological evolution of ablative craters on single-crystal magnesium under subpicosecond laser irradiation are investigated using molecular dynamics(MD) simulations and *** simulation results exhibit that the main failure mode of single-crystal Mg film irradiated by a low fluence and long pulse width laser is the ejection of surface atoms,which has laser-induced high ***,under high fluence and short pulse width laser irradiation,the main damage mechanism is nucleation fracture caused by stress wave reflection and superposition at the bottom of the *** addition,Mg[0001] has higher pressure sensitivity and is more prone to ablation than Mg[0001].The evolution equation of crater depth is established using multi-pulse laser ablation simulation and verified by *** results show that,under multiple pulsed laser irradiation,not only does the crater depth increase linearly with the pulse number,but also the quadratic term and constant term of the fitted crater profile curve increase linearly.

关键词： laser-material interaction molecular dynamics(MD)simulation ablation crater morphology magnesium

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A General Simulation Method for Complex Deformation of Irregular-Shaped Origami Configurations

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Acta Mechanica Solida Sinica 2024年第1期37卷 90-98页

作者： Zhaochen Dong Yichao Zhu Xu Guo State Key Laboratory of Structural Analysis for Industrial Equipment Department of Engineering MechanicsInternational Research Center for Computational MechanicsDalian University of TechnologyDalian 116023China

Most existing treatments for origami-folding simulations have focused on regular-shaped *** article aims to introduce a general strategy for simulating and analyzing the deformation process of irregular shapes by means of computational capabilities *** better simulate origami deformation with folding orders,the concept of plane follow-up is introduced to achieve automated computer simulation of complex folding patterns,thereby avoiding intersection and penetration between *** on the evaluation criteria such as the lowest storage energy with tightening and the fastest pace from tightening to unfolding,the optimal crease distribution patterns for four irregular(‘N’-,‘T’-,‘O’-,and‘P’-shaped)origami configurations are then presented under five *** the dimensions of the origami are fixed,it is discovered that simpler folding patterns lead to faster deformation of the origami *** the folding complexity is fixed,higher strain energy results in more rapid origami expansion.

关键词： Irregular-shaped origami Complex deformation Computer-aided origami design General simulation

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Efficient multi-objective CMA-ES algorithm assisted by knowledge-extraction-based variable-fidelity surrogate model

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Chinese Journal of Aeronautics 2023年第6期36卷 213-232页

作者： Zengcong LI Kuo TIAN Shu ZHANG Bo WANG State Key Laboratory of Structural Analysis for Industrial Equipment Department of Engineering MechanicsDalian University of TechnologyDalian 116024China

To accelerate the multi-objective optimization for expensive engineering cases, a Knowledge-Extraction-based Variable-Fidelity Surrogate-assisted Covariance Matrix Adaptation Evolution Strategy(KE-VFS-CMA-ES) is presented. In the first part, the KE-VFS model is established. Firstly, the optimization is performed using the low-fidelity surrogate model to obtain the Low-Fidelity Non-Dominated Solutions(LF-NDS). Secondly, aiming to obtain the High-Fidelity(HF) sample points located in promising areas, the K-means clustering algorithm and the space-filling strategy are used to extract knowledge from the LF-NDS to the HF space. Finally,the KE-VFS model is established by means of the obtained HF and LF sample points. In the second part, a novel model management based on the Modified Hypervolume Improvement(MHVI) criterion and pre-screening strategy is proposed. In each generation of KE-VFS-CMA-ES, excessive candidate points are firstly generated and then calculated by the MHVI criterion to find out a few potential points, which will be evaluated by the HF model. Through the above two parts,the promising areas can be detected and the potential points can be screened out, which contributes to speeding up the optimization process twofold. Three classic benchmark functions and a time-consuming engineering case of the aerospace integrally stiffened shell are studied, and results illustrate the excellent efficiency, robustness and applicability of KE-VFS-CMA-ES compared with other four known multi-objective optimization algorithms.

关键词： Covariance matrix adaptation evolution strategy Model management Multi-objective optimization Surrogate-assisted evolutionary algorithm Variable-fidelity surrogate model

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Fatigue reliability assessment of turbine blade via direct probability integral method

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Chinese Journal of Aeronautics 2025年第4期38卷 305-320页

作者： Guohai CHEN Pengfei GAO Hui LI Dixiong YANG State Key Laboratory of Structural Analysis Optimization and CAE Software for Industrial EquipmentSchool of Mechanics and Aerospace EngineeringDalian University of TechnologyDalian 116024China

Fatigue analysis of engine turbine blade is an essential *** to various uncertainties during the manufacture and operation,the fatigue damage and life of turbine blade present *** this study,the randomness of structural parameters,working condition and vibration environment are considered for fatigue life predication and reliability ***,the lowcycle fatigue problem is modelled as stochastic static system with random parameters,while the high-cycle fatigue problem is considered as stochastic dynamic system under random ***,to deal with the two failure modes,the novel Direct Probability Integral Method(DPIM)is proposed,which is efficient and accurate for solving stochastic static and dynamic *** probability density functions of accumulated damage and fatigue life of turbine blade for low-cycle and high-cycle fatigue problems are achieved,***,the time–frequency hybrid method is advanced to enhance the computational efficiency for governing equation of ***,the results of typical examples demonstrate high accuracy and efficiency of the proposed method by comparison with Monte Carlo simulation and other *** is indicated that the DPIM is a unified method for predication of random fatigue life for low-cycle and highcycle fatigue *** rotational speed,density,fatigue strength coefficient,and fatigue plasticity index have a high sensitivity to fatigue reliability of engine turbine blade.

关键词： Engine turbine blade Low-cycle fatigue High-cycle fatigue Fatigue reliability Direct probability integral method

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Effect of boundary conditions on shakedown analysis of heterogeneous materials

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Applied Mathematics and mechanics(English Edition) 2024年第1期45卷 39-68页

作者： Xiuchen GONG Yinghao NIE Gengdong CHENG Kai LI State Key Laboratory of Structural Analysis Optimization and CAE Software for Industrial EquipmentInternational Research Center for Computational MechanicsDepartment of Engineering MechanicsDalian University of TechnologyDalian 116023Liaoning ProvinceChina

The determination of the ultimate load-bearing capacity of structures made of elastoplastic heterogeneous materials under varying loads is of great importance for engineering analysis and design. Therefore, it is necessary to accurately predict the shakedown domains of these materials. The static shakedown theorem, also known as Melan's theorem, is a fundamental method used to predict the shakedown domains of structures and materials. Within this method, a key aspect lies in the construction and application of an appropriate self-equilibrium stress field(SSF). In the structural shakedown analysis, the SSF is typically constructed by governing equations that satisfy no external force(NEF) boundary conditions. However, we discover that directly applying these governing equations is not suitable for the shakedown analysis of heterogeneous materials. Researchers must consider the requirements imposed by the Hill-Mandel condition for boundary conditions and the physical significance of representative volume elements(RVEs). This paper addresses this issue and demonstrates that the sizes of SSFs vary under different boundary conditions, such as uniform displacement boundary conditions(DBCs), uniform traction boundary conditions(TBCs), and periodic boundary conditions(PBCs). As a result, significant discrepancies arise in the predicted shakedown domain sizes of heterogeneous materials. Built on the demonstrated relationship between SSFs under different boundary conditions, this study explores the conservative relationships among different shakedown domains, and provides proof of the relationship between the elastic limit(EL) factors and the shakedown loading factors under the loading domain of two load vertices. By utilizing numerical examples, we highlight the conservatism present in certain results reported in the existing literature. Among the investigated boundary conditions, the obtained shakedown domain is the most conservative under ***, utilizing PBCs to

关键词： heterogeneous material self-equilibrium stress field(SSF) shakedown analysis effect of boundary conditions

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A new discrepancy for sample generation in stochastic response analyses of aerospace problems with uncertain parameters

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Chinese Journal of Aeronautics 2024年第12期37卷 192-211页

作者： Feng WU Yuelin ZHAO Yuxiang YANG Xiaopeng ZHANG Ning ZHOU State Key Laboratory of Structural Analysis Optimization and CAE Software for Industrial EquipmentSchool of Mechanics and Aerospace EngineeringDalian University of TechnologyDalian 116024China

Good distribution of samples and weights can improve the computational accuracy and efficiency in the stochastic response analyses of aerospace problems with uncertain *** work proposes a new Generalized L2 Discrepancy based on a General Point(GL2D-GP)for generating samples and their corresponding *** proposed GL2D-GP is an extension of the existing discrepancy by introducing the non-same weights and a smaller box to measure probability *** the GL2D-GP can yield a weight optimization formula that generates a set of optimal non-identical weights for a given sample *** minimizing the GL2D-GP assigned to the set of optimal non-same weights,a new sample and weight generation method is *** the proposed method,the samples can be easily generated in terms of the generalized Halton formula with a series of optimal permutation vectors which are found by the intelligent evolutionary *** the sample set is obtained,the optimal weights can be generated in terms of the weight optimization *** numerical examples are presented to verify the high accuracy,efficiency,and strong robustness of the proposed sample generation method based on GL2D-GP.

关键词： Stochastic systems Aerospace engineering Monte Carlo methods Sample generation Generalized discrepancy Non-same weights

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ABAQUS and ANSYS Implementations of the Peridynamics-Based Finite Element Method(PeriFEM)for Brittle Fractures

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Computer Modeling in engineering & Sciences 2023年第9期136卷 2715-2740页

作者： Fei Han Zhibin Li Jianyu Zhang Zhiying Liu Chen Yao Wenping Han State Key Laboratory of Structural Analysis for Industrial Equipment Department of Engineering MechanicsDalian University of TechnologyDalian116023China

In this study,we propose the first unified implementation strategy for peridynamics in commercial finite element method(FEM)software packages based on their application programming interface using the peridynamics-based finite element method(PeriFEM).Using ANSYS and ABAQUS as examples,we present the numerical results and implementation details of PeriFEM in commercial FEM *** is a reformulation of the traditional FEM for solving peridynamic equations *** is considered that the non-local features of peridynamics yet possesses the same computational framework as the traditional ***,this implementation benefits from the consistent computational frameworks of both PeriFEM and the traditional *** implicit algorithm is used for both ANSYS and ABAQUS;however,different convergence criteria are adopted owing to their unique *** ANSYS,APDL enables users to conveniently obtain broken-bond information from UPFs;thus,the convergence criterion is chosen as no new broken *** ABAQUS,obtaining broken-bond information is not convenient for users;thus,the default convergence criterion is used in *** codes integrated into ANSYS and ABAQUS are both verified through benchmark examples,and the computational convergence and costs are *** results show that,for some specific examples,ABAQUS is more efficient,whereas the convergence criterion adopted in ANSYS is more ***,3D examples are presented to demonstrate the ability of the proposed approach to deal with complex engineering problems.

关键词： PeriFEM peridynamics ANSYS ABAQUS damage fracture

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mechanics of twisted and coiled tube-based artificial muscles driven by hydraulic pressure

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Science China(Technological Sciences) 2025年第4期68卷 72-81页

作者： Hao LIU Zhiya ZHANG Lei LIU Dabiao LIU Department of Engineering Mechanics School of Aerospace EngineeringHuazhong University of Science and TechnologyWuhan430074China Hubei Key Laboratory of Engineering Structural Analysis and Safety Assessment Wuhan430074China

The twisted and coiled polymer(TCP)artificial muscles driven by hydraulic pressure offer high mechanical efficiency and power *** relation between geometry,mechanics,and actuation performance for this kind of muscle is *** this study,we study the mechanics and actuation characteristics of TCP tube-based muscles driven by hydraulic pressure through experiment,theory,and finite element *** for the helical geometry and transverse isotropy of the TCP muscles,we develop a phenomenological model to predict the actuation performance of TCP tube-based *** torsional and tensile actuation characteristics of the twisted and TCP tube-based muscle driven by hydraulic pressure are *** is found that the cold drawing enhances the anisotropy of the polyvinyl chloride tube,resulting in an improved actuation performance of the twisted and TCP *** torsional actuation in the twisted tube reaches the maximum at a critical bias angle for a given pressure,while the tensile actuation in TCP muscles increases with the coil *** theoretical predictions and simulations are in good agreement with experimental *** study is significant for guiding the design of TCP tube-based muscles and achieving their precise actuation control.

关键词： artificial muscles hydraulic pressure actuation characteristics anisotropy

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An Adaptively Filtered Precise Integration Method Considering Perturbation for Stochastic Dynamics Problems

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Acta Mechanica Solida Sinica 2023年第2期36卷 317-326页

作者： Li Zhu Keqi Ye Dongwei Huang Feng Wu Wanxie Zhong State Key Laboratory of Structural Analysis Optimization and CAE Software for Industrial EquipmentDepartment of MechanicsFaculty of Vehicle Engineering and MechanicsDalian University of TechnologyDalian 116024China

The difficulty in solving stochastic dynamics problems lies in the need for a large number of repeated computations of deterministic dynamic equations,which has been a challenge in stochastic dynamics analysis and was discussed in this *** efficiently and accurately compute the exponential of the dynamics state matrix and the matrix functions due to external loads,an adaptively filtered precise integration method was proposed,which inherits the high precision of the precise integrationmethod,improves the computational efficiency and saves the memory ***,the perturbation method was introduced to avoid repeated computations of matrix exponential and terms due to external *** on the filtering and perturbation techniques,an adaptively filtered precise integration method considering perturbation for stochastic dynamics problems was *** numerical experiments,including a model of phononic crystal and a bridge model considering random parameters,were performed to test the performance of the proposed method in terms of accuracy and *** results show that the accuracy and efficiency of the proposed method are better than those of the existing precise integration method,the Newmark-βmethod and the Wilson-θmethod.

关键词： Precise integration method Stochastic dynamics problem Perturbation Filtered Computational efficiency

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Constructing uniform design tables based on restart discrete dynamical evolutionary algorithm

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Soft Computing 2024年第19期28卷 11515-11534页

作者： Zhao, Yuelin Wu, Feng Yang, Yuxiang Wei, Xindi Hu, Zhaohui Yan, Jun Zhong, Wanxie State Key Laboratory of Structural Analysis Optimization and CAE Software for Industrial Equipment Department of Engineering Mechanics Faculty of Vehicle Engineering and Mechanics Dalian University of Technology Dalian116023 China

Generating uniform design tables (UDTs) is the first step to experimenting efficiently and effectively, and is also one of the most critical steps. Thus, the construction of uniform design tables has received much attention over the past decades. This paper presents a new algorithm for constructing uniform design tables: restart discrete dynamical evolutionary algorithm (RDDE). This algorithm is based on a well-designed dynamical evolutionary algorithm and utilizes discrete rounding technology to convert continuous variables into discrete variables. Considering the optimization of UDT is a multi-objective optimization problem, RDDE uses Friedman rank to select the optimal solution with better comprehensive comparison ranking. RDDE also utilizes a simulated annealing-based restart technology to select control parameters, thereby increasing the algorithm's ability to jump out of local optima. Comparisons with state-of-the-art UDTs and two practical engineering examples are presented to verify the uniformity of the design table constructed by RDDE. Numerical results indicate that RDDE can indeed construct UDTs with excellent uniformity at different levels, factors, and runs. Especially, RDDE can flexibly construct UDTs with unequal intervals of factors that cannot be directly processed by other designs of experiment. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2024.

关键词： Simulated annealing

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