Acta Mechanica Sinica
     Acta Mechanica Sinica
  Acta Mechanica Sinica--2021, 37 (3)   Published: 31 March 2021
Review
Recent advances of hydrogel network models for studies on mechanical behaviors
Jincheng Lei, Ziqian Li, Shuai Xu, Zishun Liu
Abstract

Current constitutive theories face challenges when predicting the extremely large deformation and fracture of hydrogels, which calls for the demands to reveal the fundamental mechanism of the various mechanical behaviors of hydrogels from bottom up. Proper hydrogel network model provides a better approach to bridge the gap between the micro-structure and the macroscopic mechanical responses. This work summarizes the theoretical and numerical researches on the hydrogel network models, aiming t...

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RESEARCH PAPER
Vibration suppression of an elastic beam with boundary inerter-enhanced nonlinear energy sinks
Zhen Zhang, Hu Ding, Ye-Wei Zhang, Li-Qun Chen
Abstract

Nonlinear vibration absorbers have been widely used for vibration suppression of elastic structures, but they were usually placed within the structures. However, designing such a vibration damping device within an engineering structure is possibly difficult. In this paper, an inertial nonlinear energy sinks (NES) is mounted on the boundaries of the elastic beam to suppress its vibration. Although this vibration suppression approach is more in line with engineering requirements, it introduces ...

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A thermo-viscoelastic model for particle-reinforced composites based on micromechanical modeling
Yang Chen, Xiaohao Shi, Zhenqiang Zhao, Zaoyang Guo, Yulong Li
Abstract

Micromechanics-based constitutive models offer superior ability to estimate the effective mechanical properties for the composites, which greatly promote the computational efficiency in the multiscale analysis for composite structures. In this work, a thermo-viscoelastic model for particle-reinforced composites is proposed to estimate their thermal-mechanical coupling behaviors in terms of a micromechanics-based homogenization method in the time domain. The matrix and particles of the composi...

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Thermoelectromechanical instability of dielectric elastomer undergoes polarization saturation and temperature variation
Yaguang Guo, Liwu Liu, Yanju Liu, Jinsong Leng
Abstract

When the electric field caused by voltage reaches a certain level, the charge on the compliant electrodes will not increase owing to the polarization saturation, which would limit the deformation of the dielectric elastomer. Some experiments show that temperature also has a significant effect on the deformation of dielectric elastomer. In this work, a free energy model coupling temperature and polarization saturation is developed to characterize the thermoelectromechanical instability of diel...

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Experimental investigation of hypersonic flight-duplicated shock tunnel characteristics
C. K. Yuan, Z. L. Jiang
Abstract

Hypersonic air-breathing propulsion is one of the key techniques for future aviation and the ground aerodynamic testing for full scale test models with sufficient test time at flight conditions is of fundamental importance for verifying hypersonic air-breathing engines. Based on the backward detonation-driven concept, the hypersonic flight-duplicated shock tunnel (or JF-12 shock tunnel) has been successfully constructed and calibrated. This facility is capable of reproducing airflow for Mach ...

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Effect of Atwood number on convergent Richtmyer-Meshkov instability
Jinggang Tang, Fu Zhang, Xisheng Luo, Zhigang Zhai
Abstract

Developments of two-dimensional single-mode light/heavy interfaces driven by convergent shock waves are numerically investigated, focusing on the effect of the Atwood number on the Rayleigh-Taylor stabilization, the compressibility and the nonlinearity. Five different test gases, including CO2, Kr, R22, R12 and SF6, are considered with air as the ambient gas. It is clarified for the first time that the unperturbed interface begins to decelerate when the shock focuses at ...

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Cavity dynamics of water drop impact onto immiscible oil pool with different viscosity
Muhammad Mohasan, Anas Bin Aqeel, Pengyu Lv, Yantao Yang, Huiling Duan
Abstract

In this work, we numerically study the impact of a water droplet onto a deep oil pool. Two fluids are immiscible and the viscosity of the pool liquid is changed systematically. We focus on the cavity dynamics during the impact and especially the effects of the pool liquid viscosity and the impacting velocity. For the parameter range explored, we identify the regime where splashing occurs with corolla breaking into droplets, and the regime where no splashing is observed. Similarity is found fo...

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Characterization of material mechanical properties using strain correlation method combined with virtual fields method
Yangyang Li, Jiaqiang Li, Qiyuan Duan, Huimin Xie, Sheng Liu
Abstract

The isotropic and anisotropic behaviors are considered as the important formats of the constitutive behaviors, and can also be called the global properties. To improve the identification ability of virtual fields method (VFM) when the global properties are unknown, this paper proposes the strain correlation method (SCM) to determine the global properties before the parameter identification using the VFM. Firstly, the basic principle of SCM is described in detail. Then, the feasibility and acc...

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Concurrent topology optimization design of stiffener layout and cross-section for thin-walled structures
Quhao Li, Yongxin Qu, Yunfeng Luo, Shutian Liu
Abstract

Stiffened plates or shells are widely used in engineering structures as primary or secondary load-bearing components. How to design the layout and sizes of the stiffeners is of great significance for structural lightweight. In this work, a new topology optimization method for simultaneously optimizing the layout and cross-section topology of the stiffeners is developed to solve this issue. The stiffeners and base plates are modeled by the beam and shell elements, respectively, significantly r...

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Numerical study on the resistance of rigid projectiles penetrating into semi-infinite concrete targets
Huawei Yang, Jie Zhang, Zhiyong Wang, Zhihua Wang, Q. M. Li
Abstract

A study on the resistance of rigid projectiles penetrating into semi-infinite concrete targets is performed in this paper. Experimental data are analyzed to examine the penetration resistance during various stages of the penetration process. A numerical tool using AUTODYN hydrocode is applied in the study. The numerical results on both deceleration-time history and depth of penetration of projectiles are in good agreement with experimental data, which demonstrate the feasibility of the numeri...

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Gauss optimization method for the dynamics of unilateral contact of rigid multibody systems
Wenli Yao, Liusong Yang, Mingming Guo
Abstract

The discontinuous dynamical problem of multi-point contact and collision in multi-body system has always been a hot and difficult issue in this field. Based on the Gauss' principle of least constraint, a unified optimization model for multibody system dynamics with multi-point contact and collision is established. The paper presents the study of the numerical solution scheme, in which particle swarm optimization method is used to deal with the corresponding optimization model. The article als...

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Stochastic P-bifurcations of a noisy nonlinear system with fractional derivative element
Ya-Hui Sun, Yong-Ge Yang, Wei Xu
Abstract

This paper investigates the stochastic P-bifurcation (SPB) of a fractionally damped oscillator subjected to additive and multiplicative Gaussian white noise. Variable transformation and the stochastic averaging technique are applied to derive the expression of probability density function (PDF) of the system response. Critical conditions of the stochastic bifurcation induced by system parameters are presented based on the change in the number of extreme points of the probability density funct...

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REVIEW PAPER
Fatigue behavior of cortical bone: a review
Jingwen Li, He Gong
Abstract

Fatigue is a common cause of bone failure. As the main load-bearing tissue, cortical bone carries a considerable share of load in the whole bone. Under cyclic loading condition, microdamage may generates and accumulates in cortical bone, which further triggers the fracture of bone. It is crucial to explore the fatigue properties of cortical bone and the influential factors for both clinical diagnosis and establishment of models that can predict fatigue failure of human cortical bone. In this ...

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RESEARCH PAPER
Comparative analysis of indentation and magnetic resonance elastography for measuring viscoelastic properties
Yu Chen, Suhao Qiu, Zhao He, Fuhua Yan, Ruokun Li, Yuan Feng
Abstract

Measurement the viscoelastic properties is important for studying the developmental and pathological behavior of soft biological tissues. Magnetic resonance elastography (MRE) is a non-invasive method for in vivo measurement of tissue viscoelasticity. As a flexible method capable of testing small samples, indentation has been widely used for characterizing soft tissues. Using 2nd-order Prony series and dimensional analysis, we analyzed and compared the model parameters estimated from both ind...

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