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Nonlinear Dynamic Modeling for Joint Interfaces by Combining Equivalent Linear Mechanics with Multi-objective Optimization

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Acta Mechanica Solida Sinica 2020年第4期33卷 564-578页

作者： Dong Wang Xuanliua Fan Institute of Systems engineering China Academy of Engineering PhysicsMianyang 621099China shock and vibration of engineering materials and structures key laboratory of sichuan province Mianyang 621999China

The nonlinear dynamic modeling by combining the equivalent linear mechanics with the multi-objective optimization algorithm is proposed to describe the nonlinear behaviors of the joint *** joint interfaces are simplified as the equivalent virtual material or linear spring damper *** genetic algorithm for multi-objective optimization is then used to identify the mechanical properties of the equivalent joint by minimizing the error between the simulated dynamic characteristics and the experimental results,including the modal frequencies of the bolted joint beam and the frequency response functions(FRFs)of the rubber isolation *** FRFs are divided into several subsections with frequency-varied dynamic properties of the joint to consider the nonlinear dynamic behaviors,and the effects of subsection number and excitation amplitudes on the FRFs are also *** results show that the simulated dynamic characteristics of modal frequencies and FRFs agree well with the experimental *** the increase in the subsection number,the simulated FRFs agree better with the experimental results,indicating a good performance of modeling the nonlinear dynamic behaviors of the joint interfaces forced by different excitation *** excitation amplitudes will decrease the joint stiffness.

关键词： Joint interfaces Nonlinear dynamic Equivalent linear mechanics Frequencyvaried properties Multi-objective optimization

A PCA-Based Approach for Structural Dynamics Model Updating with Interval Uncertainty

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Acta Mechanica Solida Sinica 2019年第1期32卷 105-119页

作者： Xueqian Chen Zhanpeng Shen Xin'en Liu Institute of Systems engineering China Academy of Engineering Physics(CAEP)Mianyang 621999China shock and vibration of engineering materials and structures key laboratory of sichuan province Mianyang 621999China

Uncertainty widely exists in engineering structures,making it necessary to update the finite element(FE)modeling with *** updating approach for the FE model of structural dynamics with interval uncertain parameters is proposed in this ***,the correlations between the updating parameters and the output qualities of interest are uncorrelated by the principal component analysis(PCA),and the massive samples of major principal components are obtained using the Monte Carlo ***,the massive samples of updating parameters and output qualities are obtained by reversing transformation in the PCA,and the new samples of updating parameters are re-chosen by combining the massive samples with the experimental intervals of the qualities of ***,the 95%CI of the updating parameters is estimated by the nonparametrie kernel density estimation approach,which are regarded as the intervals of updating ***,the proposed approach is validated in simple rectangular plates and the transport mirror *** updating results evidently demonstrate the feasibility and reliability of the proposed approach.

关键词： PCA-based approach Interval uncertainty Model updating Kernel density estimation

Ballistic performance of tungsten particle/metallic glass matrix composite long rod

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Defence Technology（防务技术） 2019年第2期15卷 132-145页

作者： Ji-cheng Li Xiao-wei Chen Feng-lei Huang State key laboratory of Explosion Science and Technology Beijing Institute of Technology Institute of Systems engineering China Academy of Engineering Physics shock and vibration of engineering materials and structures key laboratory of sichuan province

In the present manuscript numerical analysis on the ballistic performance of a tungsten particle/metallic glass matrix(WP/MG) composite rod is conducted by integrating with related experimental investigations. In the corresponding finite element method(FEM) simulations a modified coupled thermomechanical constitutive model is employed to describe the mechanical properties of metallic glass(MG)matrix, and geometrical models of the WP/MG composite rod are established based on its inner structure. The deformation and failure characteristics of the rod and target materials are analyzed in detail,and the influences of various factors on the ballistic performance of the WP/MG composite long rod are discussed. Related analysis demonstrates that the penetrating performance of the WP/MG rod is similar to that of the tungsten fiber/metallic glass matrix(WF/MG) composite long rod, i.e., a "self-sharpening" behavior also occurs during the penetration process, and correspondingly its penetrating capability is better than that of the tungsten heavy alloy(WHA) rod. However, the mass erosion manner of the WP/MG rod is different and the erosion is relatively severe, thus its penetrating capability is a little lower compared with that of the WF/MG one. Moreover, the impact velocity and the target strength have significant influences on the ballistic performance of the WP/MG composite rod, whereas the effect of initial nose shape is very little.

关键词： Tungsten particle/metallic glass matrix (WP/MG)composite Ballistic performance Shear band Self-sharpening Numerical analysis

Influence of blasting load directions on tunnel stability in fractured rock mass

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Journal of Rock Mechanics and Geotechnical engineering 2022年第2期14卷 346-365页

作者： Xiaohan Li Zheming Zhu Meng Wang Yun Shu Shuai Deng Dingjun Xiao key laboratory of Deep Underground Science and engineering(Ministry of Education) College of Architecture and EnvironmentSichuan UniversityChengdu610065China shock and vibration of engineering materials and structures key laboratory of sichuan province Southwest University of Science and TechnologyMianyang621010China

Tunnels in fractured rock masses are typically damaged by dynamic disturbances from various *** investigate the influence of blasting load directions on the stability of a tunnel with a precrack nearby,blasting tests were conducted on the physical models of an external crack around a tunnel(ECT)in this *** modes of the tunnels were analysed based on stress wave *** Riedel-Hiermaier-Thoma(RHT)material model was employed to perform the numerical simulations on ECT *** distribution around the tunnels and final failure patterns of the tunnels were *** results show that,under blasting loads,the pre-crack propagates and then new cracks initiates on the incident side of the *** cracks extend towards each other and eventually *** load directions significantly influence the ultimate failure mode of the tunnel in the fractured rock *** new cracks on the shadow side of the tunnel appear at different positions when the blasting stress waves come from various *** results are meaningful to the analysis of tunnel stability and optimisation of the tunnel support scheme.

关键词： Blasting Tunnel stability Crack propagation Failure mode Numerical simulation

Surficial stability analysis of soil slope under seepage based on a novel failure mode

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Frontiers of Structural and Civil engineering 2021年第3期15卷 712-726页

作者： Jifeng LIAN Jiujiang WU School of Emergency Science Xihua UniversityChengdu610039China shock and vibration of engineering materials and structures key laboratory of sichuan province Southwest University of Science and TechnologyMianyang621010China College of Civil engineering and Architecture Wenzhou UniversityWenzhou325035China

Normally,the edge effects of surficial landslides are not considered in the infinite slope method for surficial stability analysis of soil *** this study,the limit stress state and discrimination equation of an infinite slope under saturated seepage flow were analyzed based on the Mohr-Coulomb strength ***,a novel failure mode involving three sliding zones(upper tension zone,middle shear sliding zone,and lower compression zone)was ***,based on the limit equilibrium analysis,a semi-analytical framework considering the edge effect for the surficial stability of a soil slope under downslope seepage was ***,the new failure mode was verified via a numerical finite element analysis based on the reduced strength theory with ABAQUS and some simplified methods using SLIDE *** results obtained by the new failure mode agree well with those obtained by the numerical analysis and traditional simplified methods,and can be efficiently used to assess the surficial stability of soil slopes under rainwater ***,an evaluation of the infinite slope method was performed using the semi-analytical method proposed in this *** results show that the infinite slope tends to be conservative because the edge effect is neglected,particularly when the ratio of surficial slope length to depth is relatively small.

关键词： soil slope seepage surficial failure mode stress state edge effects

Analysis of crack initiation location and its influencing factors of fretting fatigue in aluminum alloy components

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Chinese Journal of Aeronautics 2022年第6期35卷 420-436页

作者： Jian WANG Caizhi ZHOU School of Civil engineering and Architecture Southwest University of Science and TechnologyMianyang 621010China shock and vibration of engineering materials and structures key laboratory'of sichuan province Southwest University of Science and TechnologyMianyang 621010China Department of Mechanical engineering University of South CarolinaColumbia 29208United States

To promote the development of fretting fatigue assessment and control technology for aircraft components,this paper uses the Crystal Plasticity Finite Element(CPFE)method and sub-modeling technology to study the Crack Initiation Location(CIL)of fretting fatigue in Aluminum Alloy(AA)*** effects of external excitations such as normal load,tangential load,and axial stress on the CIL are *** is found that the Most Likely Cracked(MLC)site revealed in a specimen and the CIL may always be consistent after a limited number of cyclic loadings,and they are both located at the hotspot on the contact surface or in the *** MLC site may also migrate from the hotspot on the contact surface to the hotspot in the subsurface with an increase of the cyclic number,and finally transform into a *** relationship between the MLC site and the CIL of fretting fatigue and its influencing factors have also been described,as well as the identification method of the CIL of fretting fatigue,which provide theoretical and technical supports for anti-fretting fatigue design of AA components in service.

关键词： Crack nucleation Crystal plasticity Equivalent plastic strain Fretting fatigue Hotspot

Multi-scale finite element simulation on large deformation behavior of wood under axial and transverse compression conditions

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Acta Mechanica Sinica 2021年第7期37卷 1136-1151,I0002页

作者： Weizhou Zhong Zexiong Zhang Xiaowei Chen Qiang Wei Gang Chen Xicheng Huang Institute of Systems engineering China Academy of Engineering PhysicsMianyang Sichuan621999China shock and vibration of engineering materials and structures key laboratory of sichuan province Mianyang 621999China College of engineering Science University of Science and Technology of ChinaHefei 230026China Advanced Research Institute for Multidisciplinary Science Beijing Institute of TechnologyBeijing100081China The State key lab of Explosion Science and Technology Beijing Institute of TechnologyBeijing100081China

Multi-scale finite element method is adopted to simulate wood compression behavior under axial and transverse loading. Representative volume elements (RVE) of wood microfibril and cell are proposed to analyze orthotropic mechanical behavior. Lignin, hemicellulose and crystalline-amorphous cellulose core of spruce are concerned in spruce nanoscale model. The equivalent elastic modulus and yield strength of the microfibril are gained by the RVE simulation. The anisotropism of the crystalline-amorphous cellulose core brings the microfibril buckling deformation during compression loading. The failure mechanism of the cell-wall under axial compression is related to the distribution of amorphous cellulose and crystalline cellulose. According to the spruce cell observation by scanning electron microscope, numerical model of spruce cell is established using simplified circular hole and regular hexagon arrangement respectively. Axial and transverse compression loadings are taken into account in the numerical simulations. It indicates that the compression stress-strain curves of the numerical simulation are consistent with the experimental results. The wood microstructure arrangement has an important effect on the stress plateau during compression process. Cell-wall buckling in axial compression induces the stress value drops rapidly. The wide stress plateau duration means wood is with large energy dissipation under a low stress level. The numerical results show that loading velocity affects greatly wood microstructure failure modes in axial loading. For low velocity axial compression, shear sliding is the main failure mode. For high velocity axial compression, wood occur fold and collapse. In transverse compression, wood deformation is gradual and uniform, which brings stable stress plateau.

关键词： Multi-scale model Representative volume element Spruce Energy dissipation Wood cell

Further numerical investigation on concrete dynamic behaviors with considering stress non-equilibrium in SHPB test based on the waveform features

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Acta Mechanica Sinica 2020年第4期36卷 873-886页

作者： T.H.Lv X.W.Chen Y.J.Deng G.Chen State key laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China Advanced Research Institute of Multidisciplinary Science Beijing Institute of TechnologyBeijing 100081China shock and vibration of engineering materials and structures key laboratory of sichuan province Southwest University of Science and TechnologyMianyang 621000China Institute of Systems engineering China Academy of Engineering PhysicsMianyang 621999China

In this study,with the meso-scale model reliably validated in our previous work(Construction and Building materials,2018),the waveform features of plain concrete under various loading conditions and especially with considering stress non-equilibrium are reliably reproduced and *** with waveform features,the violation indicator of the specimen stress equilibrium in the split Hopkinson pressure bar test is identified for concrete-like damage softening *** concrete material behaviors for stress non-equilibrium are further analyzed,*** dynamic increase factor(DIF)and damage development,*** conception of“damage failure volume”is introduced,and a new method of defining the development of concrete dynamic damage is given in the nimierical ***’s more,the“compression wave”and“double peak”phenomena observed in the experiment are further interpreted based on the means of numerical *** features how to reflect the concrete material properties is also *** results show that,the disappearance of the“double peak” phenomenon of reflection curve under high strain rate can be regarded as the indicator of the violation of stress *** the violation of the stress equilibrium,the relevant DIFs of the concrete specimen will not change ***,the concrete specimen will turn into structural response from material *** conception of“damage failure volume”can well explain the generation of the“double peak”phenomenon of the reflection *** “compression wave” phenomenon of reflection curve under lower strain rates is derived from the unloading expansion recovery of the concrete ***,under the same loading condition,the amplitude of the first peak of the reflection curve can be used as the evaluation standard of the bonding quality between mortar and aggregates.

关键词： Concrete material Split Hopkinson pressure bar test Numerical investigation Waveform feature Stress non-equilibrium Damage failure volume

基于多级松弛机制的形状记忆聚氨酯循环热-力学本构模型

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Acta Mechanica Sinica 2024年第1期40卷 210-225页

作者：梁志鸿李建陈开卷于超阚前华 Applied Mechanics and Structure Safety key laboratory of sichuan province School of Mechanics and Aerospace EngineeringSouthwest Jiaotong UniversityChengdu 611756China shock and vibration of engineering materials and structures key laboratory of sichuan province Mianyang 621999China

松弛作为形状记忆聚合物的固有特性,在其机械变形和形状记忆行为中起着至关重要的作用.在形状记忆过程中,松弛行为包含了短期、中期和长期机制,这些机制共同组成了多级松弛机制.基于多级松弛机制,结合热弹性行为和相转变模型,在有限变... 详细信息

松弛作为形状记忆聚合物的固有特性,在其机械变形和形状记忆行为中起着至关重要的作用.在形状记忆过程中,松弛行为包含了短期、中期和长期机制,这些机制共同组成了多级松弛机制.基于多级松弛机制,结合热弹性行为和相转变模型,在有限变形框架下建立了热致形状记忆聚氨酯的循环热-力学本构模型。在此模型中,着重考虑黏度随温度的变化,优化了相转变模型框架中温度对机械变形的影响。为了进一步描述橡胶相和冻结相之间的循环转变行为,引入循环的储存应变比,表征了循环形状记忆过程中变形的储存和释放机制与相转变之间的关系。与不同应变幅值和应变速率下的循环形状记忆实验结果对比,验证了所建立的基于多级松弛机制的循环热-力学本构模型能合理地描述形状记忆聚氨酯的循环形状记忆行为.

关键词：形状记忆行为机械变形形状记忆聚合物循环热形状记忆聚氨酯释放机制有限变形应变比