Showing papers in "Acta Mechanica Sinica in 2023"

On methodology and application of smoothed particle hydrodynamics in fluid, solid and biomechanics

Abstract: Smoothed particle hydrodynamics (SPH), as one of the earliest meshfree methods, has broad prospects in modeling a wide range of problems in engineering and science, including extremely large deformation problems such as explosion and high velocity impact. This paper aims to provide a comprehensive overview on the recent advances of SPH method in the fields of fluid, solid, and biomechanics. First, the theory of SPH is described, and improved algorithms of SPH with high accuracy are summarized, such as the finite particle method (FPM). Techniques used in SPH method for simulating fluid, solid and biomechanics problems are discussed. The δ-SPH method and Godunov SPH (GSPH) based on the Riemann model are described for handling instability issues in fluid dynamics. Next, the interface contact algorithm for fluid-structure interaction is also discussed. The common algorithms for improving the tensile instability and the framework of total Lagrangian SPH are examined for challenging tasks in solid mechanics. In terms of biomechanics, the governing equations and the coupling forces based on SPH method are exemplified. Then, various typical engineering applications and recent advances are elaborated. The application of fluid mainly depicts the interaction between fluid and rigid body as well as elastomer, while some complicated fluid-structure interaction ocean engineering problems are also presented. In the aspect of solid dynamics, galaxy, geotechnical mechanics, explosion and impact, and additive manufacturing are summarized. Furthermore, the recent advancements of SPH method in biomechanics, such as hemodynamically and gut health, are discussed in general. In addition, to overcome the limitations of computational efficiency and computational scale, the multiscale adaptive resolution, the parallel algorithm and the automated mesh generation are addressed. The development of SPH software in China and abroad is also summarized. Finally, the challenging task of SPH method in the future is summarized. In future research work, the establishment of multi-scale coupled SPH model and deep learning technology in solid and biodynamics will be the focus of expanding the engineering applications of SPH methods.光滑粒子流体动力学(smoothed particle hydrodynamics, SPH)作为最早发展的无网格粒子方法之一, 对于模拟爆炸、冲击等涉及大变形问题, 具有广阔的发展前景. 本文对SPH方法在流体、固体和生物力学领域的改进算法和工程应用进行了全面介绍. 阐述了SPH的基本理论和高精度SPH改进算法, 分析了流体、固体和生物力学领域的改进技术. 在模拟流体问题时, 采用δ-SPH和GSPH方法解决了流体不稳定性的问题, 并且讨论了流固耦合中的界面接触方法. 针对固体的数值模拟, 总结了三种传统改进方法(如应力点法、守恒光滑法、人工应力法)和Total Lagrangian SPH方法, 改善了拉伸不稳定性问题; 在生物力学方面, 阐述了SPH控制方程和相互作用力的计算方法. 本文综述了近年来SPH方法的应用进展, 包括复杂海洋工程中的流固耦合问题, 固体领域的天体、岩土力学、爆炸冲击以及增材制造等工程应用和生物力学中血流动力学、肠道健康和植物生长等典型应用; 并分析了国内外SPH软件的发展, 介绍了多尺度自适应分辨率方法、并行计算方法和网格自动生成技术来克服数值模拟方法在计算效率和计算规模上的限制. 最后对目前存在的问题进行总结与展望, 包括提高SPH算法的数值精度、如何精确描述固体的损伤与断裂问题和计算精度与效率之间的平衡等. 在未来研究中, 建立多尺度耦合SPH模型和深度学习将是进一步拓宽SPH方法应用的重要方向.

Virtual element formulation for gradient elasticity

Abstract: Abstract The virtual element method has been developed over the last decade and applied to problems in solid mechanics. Different formulations have been used regarding the order of ansatz, stabilization of the method and applied to a wide range of problems including elastic and inelastic materials and fracturing processes. This paper is concerned with formulations of virtual elements for higher gradient elastic theories of solids using the possibility, inherent in virtual element methods, of formulating C 1 -continuous ansatz functions in a simple and efficient way.

A strain mode spectral digital image correlation method for displacement field analysis

Abstract: Abstract A spectral image correlation method considering the effect of displacement gradients upon displacement analysis in the Fourier frequency domain is proposed. A spectral image correlation criterion is studied and established to match the target subset image with the reference subset image in the frequency domain. An iterative algorithm for calculating displacement and strain is then derived, and the Hessian matrix remains unchanged within an iterative process. During the formation of the Hessian matrix, the greyscale gradients of the reference subset image can be calculated using the fast Fourier transform with high computational efficiency and accuracy. An accurate Fourier transform resampling technique, instead of the traditional interpolation method, is used to reconstruct or up-date the target image at a subpixel position in the deformed subset image. To verify the validity and accuracy of the proposed method, a series of images (2D-Challenge 1.0, sample 6) provided by the International DIC Challenge Committee (IDCC) was used for displacement analysis. The analyzed error results show that the proposed method is better than the published literature in accuracy. The second simulation experimental result with a strain of 50% is performed and the corresponding displacement accuracy is about 0.0032 pixel under the condition of 41 × 41 subset. Finally, a 14.85% uniaxial tensile test of a silicone rubber specimen is performed, and the analyzed displacement and strain distribution are given.