Acta Mechanica Sinica
     Acta Mechanica Sinica
  Acta Mechanica Sinica--2021, 37 (4)   Published: 25 April 2021
Non-contact optical dynamic measurements at different ranges: a review
Yu Fu · Yang Shang · Wenxin Hu · Bin Li · Qifeng Yu

Optical dynamic measurements are widely used for non-contact vibration, continuous deformation, or moving objects. Various measurement techniques were developed for different deformation amplitudes. This paper reviews three types of technique for different measurement ranges: interferometric techniques for deformation or vibration (nanometer to sub-millimeter amplitude) whose measurement accuracies rely on phase extraction of interfereometric signal; imaging based techniques for deformation o...

Mechanical characterization of soft silicone gels via spherical nanoindentation for applications in mechanobiology
Yajun Zhang · Xiaoning Yang · Chunyang Xiong

As a biocompatible material, soft silicone gels like CY52-276 have been applied to many engineering fields associated with interactions between mammalian cells and extracellular matrices/substrates, due to its nontoxicity, ease of preparation, optical transparency and tunable mechanical properties. Precise quantification of mechanical properties of silicone gels is crucial for quantitatively investigating mechanical responses of cells to microenvironments. Addressing the material with high su...

Dispersive behavior of high frequency Rayleigh waves propagating on an elastic half space
Ning Jia · Zhilong Peng · Jianjun Li · Yin Yao · Shaohua Chen

When the wavelength of Rayleigh wave is comparable with nanometers, Rayleigh wave will become dispersive. Such an interesting phenomenon cannot be predicted by the classical theory of elastodynamics. In order to reveal the internal mechanism and influencing factors of the dispersion, a model of Rayleigh wave propagating on an elastic half space is established and analyzed by a new theory of surface elastodynamics, in which the surface effect characterized by both the surface energy density an...

Prediction on nonlinear mechanical performance of random particulate composites by a statistical second-order reduced multiscale approach
Zhiqiang Yang · Yi Sun · Yizhi Liu · Junzhi Cui

A novel statistical second-order reduced multiscale (SSRM) approach is established for nonlinear composite materials with random distribution of grains. For these composites considered in this work, the complex microstructure of grains, including their shape, orientation, size, spatial distribution, volume fraction and so on, results in changing of the macroscopic mechanical properties. The first- and second-order unit cell functions based on two-scale asymptotic expressions are constructed a...

On skin friction in wall-bounded turbulence
Zhenhua Xia · Peng Zhang · Xiang I. A. Yang

In this paper, we derive mathematical formulas for the skin friction coefficient in wall-bounded turbulence based on the Reynolds averaged streamwise momentum equation and the total stress. Specifically, with a theoretical or empirical relation of the total stress, the skin friction coefficient is expressed in terms of the mean velocity and the Reynolds shear stress in an arbitrary wall-normal region [h0, h1]. The formulas are validated using direct numerical simulation data of turbulent chan...

Numerical investigation on fluid forces of piggyback circular cylinders in tandem arrangement at low Reynolds numbers
Linfeng Chen1 · Yuhong Dong2

Numerical simulations of flows past the piggyback circular cylinders in tandem arrangement are performed by solving the variational multiscale formulation of the incompressible Navier–Stokes equations using in-house finite element method (FEM) codes. The effects of the gap-spacing-to-diameter (G/D) and the two diameter ratio (d/D) on the flow characteristics and the reductions of the root-mean-square (RMS) drag and lift coefficients are considered for Reynolds numbers (Res) are 100 and ...

Experimental investigation of critical suction velocity of coarse solid particles in hydraulic collecting
Yan Zhang · Xiaobing Lu · Xuhui Zhang · Yuxiang Chen · Hong Xiong · Lianghua Zhang

Hydraulic collecting and pipe transportation are regarded as an efficient way for exploiting submarine mineral resources such as the manganese nodules and ores. Coarse particles on the surface of the sea bed are sucked by a pipe during the mining and crushing of the mineral. In this paper, the critical suction velocity for lifting the coarse particles is investigated through a series of laboratory experiments, and the solid–liquid two-phase flow characteristics are obtained. Based on th...

Parameterized level set method for structural topology optimization based on the Cosserat elasticity
Lianxiong Chen · Ji Wan · Xihua Chu · Hui Liu

When describing the mechanical behavior of some engineering materials, such as composites, grains, biological materials and cellular solids, the Cosserat continuum theory has more powerful capabilities compared with the classical Cauchy elasticity since an additional local rotation of point and its counterpart (couple stress) are considered in the Cosserat elasticity to represent the material microscale effects. In this paper, a parameterized level set topology optimization method is develope...

Experimental investigation on the movement mechanism of top coal in steeply inclined ultra thick coal seams
Jiachen Wang · Fei Liu · Zhaohui Wang

The pre-blasting zones have a significant influence on the coal broken and the recovery rate of the top coal caving mining. This paper explores the coal movement mechanism in the top coal with pre-blasting zones based on the geological parameters of Jiangcang No. 1 mine in the western of China. The steeply inclined ultra-thick coal seam was mined by using the sublevel top-coal caving mining method. The geo-image process system (GIPS) software was used to track the mark points on the coal and ...

Coupling electro?mechanical behaviors in the interdigital electrode device of ferroelectrics
Suxin Pan · Shilin Xie · Qun Li

The electro-mechanical coupling behaviors of ferroelectric devices with interdigital electrodes may become complicated due to the material inhomogeneity and local field concentration under the complex working conditions. In this paper, a ferroelectric model, drawn from the typical interdigital electrode structure of a ferroelectric sensor, is established based on phase field theory, to study the polarization evolution and explore the evolution laws in ferroelectrics. Numerical results show th...

A study on boundary integral equations for dynamic elastoplastic analysis for the plane problem by TD-BEM
Hongjun Li · Weidong Lei · Rui Chen · Qiang Hu

The equivalent stress fundamental solution for the elastoplastic dynamic plane strain problem is proposed to transform the virtual work in the third direction to the plane. Subsequently, based on Betti reciprocal theorem, by adopting the time dependent fundamental solutions in terms of displacement, traction and equivalent stress, the boundary integral equations for dynamic elastoplastic analysis for the plane strain problem are established. The establishment procedures for the displacement a...

Energy fow characteristics of friction induced nonlinear vibrations in a water lubricated bearing shaft coupled system
Li Qin · Hongling Qin · Jing Tang Xing

Based on the energy flow theory of nonlinear dynamical system, the stabilities, bifurcations, possible periodical/chaotic motions of nonlinear water-lubricated bearing-shaft coupled systems are investigated in this paper. It is revealed that the energy flow characteristics around the equlibrium point of system behaving in the three types with different friction-paramters. (a) Energy flow matrix has two negative and one positive energy flow factors, constructing an attractive local zeroenergy ...

Regulation of thermoelastic properties of concave-packaged DNA adsorption films and its relevant microcantilever detection signals
C. X. Wu · N. H. Zhang · C. Y. Zhang · J. Z. Wu

The packing patterns have close correlation with the thermoelastic properties of DNA adsorption films and the relevant detection signals of microcantilevers. In this paper, we investigate the influence of packing patterns on the thermoelastic properties of DNA adsorption films, the detection signals of microcantilevers and their temperature dependence. First, the Parsegian's empirical potential based on a mesoscopic liquid crystal theory is employed to describe the interaction energy among co...

Oscillation and bistable switching dynamical behavior of p53 regulated by PTEN upon DNA damage
Nan Liu · Hongli Yang · Shasha Li · Danni Wang · Liangui Yang

The tumor suppressor p53 plays a key regulatory role in the response of cells to various stresses. It have experimentally shown that p53 can exhibit rich dynamic behaviors under DNA damage. In order to study the meticulous mechanism, we construct a coupling model including p53-murine double minute 2 (Mdm2) negative feedback loop (NFL) and p53-phosphatase and tensin homolog (PTEN)-Mdm2 positive feedback loop (PFL). By making use of bifurcation analysis and Binomial τ -leap algorithm, we co...

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