今日更新：International Journal of Solids and Structures 1 篇，Journal of the Mechanics and Physics of Solids 3 篇，Mechanics of Materials 2 篇，Thin-Walled Structures 4 篇
International Journal of Solids and Structures
Effective toughness based on Eshelby transformation theory for heterogeneous composites
Yun Xu, Yao Long, Hengbing An, Jun Chen
doi:10.1016/j.ijsolstr.2024.113074
基于Eshelby相变理论的非均质复合材料有效韧性研究
Predicting fracture toughness of heterogeneous composites is an important and challenging problem in physics and mechanics. The dependence of effective toughness on elastic properties of phases remains unclear. Considering that energy plays an essential role in crack propagation, an energy approach is proposed to obtain effective toughness in this study. We built the relationship between effective toughness and the homogenized local surface energy. The energy is constructed by generalizing Eshelby’s equivalent inclusion formulation to heterogeneous case, which couples physical features with elastic properties. An analytical formula of effective toughness can be derived for heterogeneous composites. Based on this formula, effects of toughness and elastic properties of the phases are discussed in depth, which reveals that how elastic heterogeneity can influence the effective toughness fundamentally. It is demonstrated that the predictions of concretes and metal toughening glasses agree well with experimental evidences.
On the experimental identification of equilibrium relations and the separation of inelastic effects in soft biological tissues
Francesca Bogoni, Maximilian P. Wollner, Gerhard A. Holzapfel
doi:10.1016/j.jmps.2024.105868
软体生物组织中平衡关系的实验鉴定及非弹性效应的分离
The mechanical characterization of vascular tissues has been mainly focused on the measurement of elastic properties, while the investigation of inelastic effects has received comparatively little attention. Even the relatively simple, purely elastic description of the material behavior requires an appropriate set of experimental data that cannot be easily isolated using standard testing procedures. The presence of viscous and damage-related phenomena poses some challenges in the definition of appropriate testing protocols capable of identifying an equilibrium response, which in general does not solely represent the elastic material behavior. The primary goal of the present study is therefore to devise an experimental procedure that can distinguish and evaluate the different constitutive phenomena separately. To this end, we apply methodologies widely used in the mechanical testing of rubber-like materials and transfer them to the field of biomechanics. We performed two types of experiments in equibiaxial extensions on porcine thoracic aorta: a continuous cyclic test followed by a single-step relaxation test and a cyclic multi-step relaxation test, each at varying stretch rates. We demonstrate that the approximation of quasi-stationarity through continuous testing at slow rates is inadequate for the identification of an equilibrium relation. Alternatively, a step-wise protocol allows for the separation of equilibrium and viscous effects. This motivates a thermodynamic discussion of the experimental results in terms of energy dissipation and a closer look at the interplay of inelastic phenomena.
We propose a computationally efficient and systematically convergent approach for elastodynamics simulations. We recast the second-order dynamical equation of elastodynamics into an equivalent first-order system of coupled equations, so as to express the solution in the form of a Magnus expansion. With any spatial discretization, it entails computing the exponential of a matrix acting upon a vector. We employ an adaptive Krylov subspace approach to inexpensively and accurately evaluate the action of the exponential matrix on a vector. In particular, we use an apriori error estimate to predict the optimal Kyrlov subspace size required for each time-step size. We show that the Magnus expansion truncated after its first term provides quadratic and superquadratic convergence in the time-step for nonlinear and linear elastodynamics, respectively. We demonstrate the accuracy and efficiency of the proposed method for one linear (linear cantilever beam) and three nonlinear (nonlinear cantilever beam, soft tissue elastomer, and hyperelastic rubber) benchmark systems. For a desired accuracy in energy, displacement, and velocity, our method allows for 10−100× larger time-steps than conventional time-marching schemes such as Newmark-β method. Computationally, it translates to a ∼1000× and ∼10−100× speed-up over conventional time-marching schemes for linear and nonlinear elastodynamics, respectively.
In this contribution, we present a gradient damage model for anisotropic textile reinforcements including fiber inextensibility and fiber sliding. In contrast to previous works, the gradient damage formulation stems not from a numerical regularization basis but from the thermodynamics of internal variables. It results in a nonlocal term as the internal energy of fiber bending with measurable nonlocal parameter. Furthermore, to guarantee a priori that rotations and reflections determined by orthogonal tensors among the symmetry group do not affect the response function of the anisotropic constitutive law, a novel mesoscopic kinematic measure for the representative volume element of the fabric is defined on the basis of the analytical network-averaging concept. Such kinematic measure is of crucial importance for material modeling of damage-elastoplasticity in anisotropic textile reinforcements, and allows for analytical descriptions of inter- and intra-ply sliding of fibers. A mixed finite element formulation is then presented for textile reinforcements taking into account fiber inextensibility. The predictive capability of the computational model is demonstrated by comparing with multiple experimental datasets of dry textile fabrics.
Damage ratio strength criterion for asphalt mixtures and its application in rutting prediction
Xia Wu, Faxing Ding, Jiaqi Chen, Leixin Nie, Zhiwu Yu
doi:10.1016/j.mechmat.2024.105165
沥青混合料损伤比强度判据及其在车辙预测中的应用
The current damage ratio strength theory is employed to predict the multiaxial strength of asphalt mixtures at various temperatures. Based on the dimensionless triaxial strength of asphalt mixtures, the values of six empirical parameters are recommended to establish the corresponding dimensionless strength criterion. The multiaxial strength data of diverse asphalt mixtures, including OGFC-13, AC-13, AC-20, AC-25, SMA-13, and SUP12.5 at different temperatures, are employed to validate the proposed criterion, which is then compared with other criteria. The results indicate that the suggested dimensionless strength criterion with uniform parameter values can accurately predict the true triaxial, confining triaxial, and biaxial strength values of asphalt mixtures across various temperatures. Furthermore, the proposed criterion is employed to elucidate the mechanical mechanism of rutting, offering a valuable insight for predicting flow rutting of pavement under loads.
Integrating MIL and Mori–Tanaka methods for microstructural analysis and mechanical behaviour prediction in heterogeneous materials
Lívia M. Nogueira, Lavinia A. Borges, Daniel A. Castello
doi:10.1016/j.mechmat.2024.105167
整合MIL和Mori-Tanaka方法在非均质材料的微观结构分析和力学行为预测
This paper explores heterogeneous materials, investigating their intricate nature characterized by structural and property variations across length scales. These variations, stemming from a variety of phases and structural constituents, lead to orientation-dependent properties, and challenge material isotropy assumptions. The present work focuses on unraveling mechanical behaviour for material selection and predictive modeling. More specifically, this paper proposes a strategy for micromechanical analyses integrating the Mori–Tanaka (M-T) homogenization model and the Mean Intercept Length (MIL) morphology-based method. The initial analysis examines the impact of both pore shape and distribution on microstructural characterization, replicating isotropic and anisotropic conditions for certain scenarios. MIL proves effective for microstructure orientation analysis, regardless of porosity. Subsequently, the M-T method is applied to estimate Young’s modulus, and its relationship with pore shape, orientation, and volume fraction is investigated. This investigation into Young’s modulus provides valuable insights into the proposed framework’s capability to uncover the intricate relationship between microstructural features and macroscopic properties within heterogeneous materials. The overall framework presented in this paper holds promise for practical applications in predicting properties in real materials using micro-CT images, contributing to a deeper understanding of these complex materials and their behaviour.
New 3D Petal-like Structures with Lightweight, High Strength, High Energy Absorption, and Auxetic Characteristics
Zhen-Yu Li, Wei-Ming Zhang, Wei-Jing Wang, Mabel Mei Po Ho, Jian Xiong, Jin-Shui Yang, Xin-Tao Wang, Minglonghai Zhang, Hong Hu
doi:10.1016/j.tws.2024.112483
新型3D花瓣状结构，具有轻量化、高强度、高能量吸收和增减特性
A novel type of petal-like structure that exhibits superior mechanical properties, was proposed and fabricated by integrating advantages of metamaterial, multi-stage deformation, and high strength of fiber-reinforced composites. Compression testing and finite element analysis were first conducted on three petal-like structures formed with different angles and made from fiber-reinforced composites. The findings indicated that these composite-based multi-cell structures can also exhibit a satisfactory stress plateau stage through judicious structural design. After ensuring the structures' performance under quasi-static compression load, the impact resistance of the new structures was further examined. It was found that the structure's auxetic characteristics diminished under low-speed impact load. However, under a 20J impact load, the structures exhibited energy absorption characteristics (SEA) that surpassed those of both conventional and other new auxetic structures by 8-40 times. These promising results demonstrate that the newly designed petal-like structures have high potential applications in various fields such as construction and automotive industries.
The thin-walled deployable composite boom (DCB) features the advantages of high deployment-to-package envelope ratio and elastic self-development, which is an enduring topic of interest in the field of lightweight aerospace structures. The structural design and performance demonstration was proposed herein for a roll-out membrane antenna (ROMA) based on DCBs. Firstly, a simplified analytical algorithm was formulated for approximate fundamental frequencies of the ROMA frame structure, and the two types of first-order torsional modal shapes of the frame structure was investigated with respect to configurational design parameters. In sequentially, the bending, swing and the two distinct torsional fundamental frequencies of the ROMA frame were estimated comparatively. Furthermore, the effects of the equilibrated tension from the membrane array on the bending fundamental frequency of the ROMA structure was investigated by assuming a simplified mass distribution model for the thin-film structures. Finally, The simplified analytical algorithm was used for structural design of an AIS/VDE (automatic identification system/VHF data exchange system) ROMA and its performance was validated through numerical simulations and ground tests. The successful deployment and operation of the AIS/VDE ROMA on the Pujiang-2 satellite further demonstrated the practical aerospace application significance of thin-walled DCBs.
The attitude angles of a projectile moving through a liquid are important factors that influence the dynamic failure of liquid-filled structures induced by hydrodynamic ram (HRAM). In this study, the effect of the attitude angles of a cylindrical projectile on the shapes of the petal hole in the rear plate of a kerosene-filled tank was investigated through ballistic impact experiments using three-dimensional digital image correlation, finite element simulations, and a back propagation neural network (BPNN). The inclination angle λ characterizing the shapes of the petal hole was related to the projection shapes of the projectile when impacting on the rear plate. The formation of petal-hole shapes was also accompanied by the formation of plastic hinge lines in the rear plate. Additionally, a method combining a BPNN and physical equations that accurately predict the drag coefficient and motion of a projectile moving through a liquid was proposed. A function describing the shapes of the petal hole was provided in the 2D space of the two initial attitude angles. The results provide offer insights into trajectory stability during liquid entry and aid in predicting the dynamic failure mode of a liquid-filled tank induced by HRAM.
The effect of cold forming residual stresses in local fatigue approaches: A numerical perspective
Carlos Souto, Marco Parente, José Correia, Abílio de Jesus
doi:10.1016/j.tws.2024.112476
局部疲劳方法中冷成形残余应力的影响:数值视角
Thin-walled structures generally rely on cold-formed mild steel profiles. Due to cold forming, a significant formation of residual stresses impacts their overall fatigue behaviour. In this work, a state-of-the-art framework for fatigue life prediction is proposed and applied to both roll-formed and press-braked full-scale profiles. In summary, the profile’s manufacturing process is numerically simulated to obtain a representative residual stress field. These results are then used as the initial state during a subsequent structural and fatigue analysis. A clear detrimental residual stress effect is verified. Importantly, however, is to note that prediction accuracy increases significantly when these effects are considered.
