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
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.
预测非均相复合材料的断裂韧性是物理力学领域的一个重要而富有挑战性的问题。有效韧性与相弹性性能的关系尚不清楚。考虑到能量在裂纹扩展过程中起着至关重要的作用,本研究提出了一种获取有效韧性的能量法。建立了有效韧性与均质局部表面能之间的关系。将Eshelby等效包合公式推广到物理特征与弹性特性耦合的非均质情况,构造了能量。推导出非均相复合材料有效韧性的解析公式。在此基础上,深入讨论了相的韧性和弹性性能的影响,揭示了弹性非均质性对有效韧性的根本影响。结果表明,混凝土和金属增韧玻璃的预测结果与实验结果吻合较好。
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.
维管组织的力学表征主要集中在弹性特性的测量上,而对非弹性效应的研究相对较少。即使是相对简单的,对材料行为的纯弹性描述也需要一组适当的实验数据,而这些数据不能用标准测试程序轻易地分离出来。黏性和损伤相关现象的存在对确定平衡响应的适当测试方案提出了一些挑战,平衡响应通常并不仅仅代表弹性材料的行为。因此,本研究的主要目标是设计一个实验程序,可以分别区分和评估不同的本构现象。为此,我们将广泛应用于类橡胶材料力学测试的方法转移到生物力学领域。我们在猪胸主动脉上进行了两种类型的等双轴伸展实验:连续循环测试,然后是单步放松测试和循环多步放松测试,每一种测试都以不同的拉伸速率进行。我们证明,通过缓慢速率连续测试的准平稳近似不足以识别平衡关系。或者,一步一步的协议允许分离平衡和粘性效应。这激发了从能量耗散角度对实验结果进行热力学讨论,并更仔细地观察非弹性现象的相互作用。
Exponential time propagators for elastodynamics
Paavai Pari, Bikash Kanungo, Vikram Gavini
doi:10.1016/j.jmps.2024.105871
弹性动力学的指数时间传播算子
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.
我们提出了一种计算高效、系统收敛的弹性动力学模拟方法。我们将弹性动力学的二阶动力学方程重构为一个等效的一阶耦合方程系统,从而以马格努斯展开的形式表达解。在任何空间离散化的情况下,都需要计算作用于矢量的矩阵的指数。我们采用自适应克雷洛夫子空间方法,以低成本准确评估指数矩阵对矢量的作用。特别是,我们使用先验误差估计来预测每个时间步长所需的最佳克雷洛夫子空间大小。我们证明,在第一项之后截断的马格努斯展开分别为非线性和线性弹性力学提供了二次收敛和超二次收敛的时间步长。我们对一个线性(线性悬臂梁)和三个非线性(非线性悬臂梁、软组织弹性体和超弹性橡胶)基准系统演示了所提方法的准确性和效率。对于所需的能量、位移和速度精度,我们的方法允许的时间步长比 Newmark-β 方法等传统时间行进方案大 10-100 倍。在计算方面,与线性和非线性弹性动力学的传统时间行进方案相比,我们的方法分别提高了 1000 倍和 10-100 倍的速度。
Modeling of textile composite using analytical network-averaging and gradient damage approach
Vu Ngoc Khiêm, Mahmood Jabareen, Rabin Poudel, Xuefeng Tang, Mikhail Itskov
doi:10.1016/j.jmps.2024.105874
基于分析网络平均和梯度损伤方法的纺织复合材料建模
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.
在这篇文章中,我们提出了一个梯度损伤模型的各向异性纺织增强包括纤维的不延伸性和纤维滑动。与以往的工作不同,梯度损伤公式不是基于数值正则化基础,而是基于内变量的热力学。得到非局部项作为光纤弯曲内能,具有可测量的非局部参数。此外,为了保证对称群中正交张量所决定的旋转和反射不会先验地影响各向异性本构律的响应函数,基于解析网络平均的概念,定义了一种新的具有代表性的织物体元的细观运动学测度。这种运动学测量对于各向异性纺织增强材料的损伤弹塑性建模具有重要意义,并允许对纤维的层间和层内滑动进行分析描述。然后提出了考虑纤维不可扩展性的纺织增强材料的混合有限元公式。通过与多个实验数据集的比较,验证了计算模型的预测能力。
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.
采用当前损伤比强度理论对沥青混合料在不同温度下的多轴强度进行了预测。根据沥青混合料的无量纲三轴强度,推荐6个经验参数的取值,建立相应的无量纲强度准则。采用OGFC-13、AC-13、AC-20、AC-25、SMA-13、SUP12.5等不同沥青混合料在不同温度下的多轴强度数据对所提出的准则进行验证,并与其他准则进行比较。结果表明,所提出的参数值统一的无量纲强度准则能够准确预测沥青混合料在不同温度下的真三轴、围三轴和双轴强度值。此外,该准则还阐明了车辙的力学机理,为荷载作用下路面流动车辙的预测提供了有价值的见解。
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.
本文探讨了非均质材料,研究了其复杂的性质,其特征是结构和性质在长度尺度上的变化。这些变化源于各种相和结构成分,导致取向依赖的性质,并挑战材料的各向同性假设。目前的工作重点是揭示材料选择和预测建模的机械行为。更具体地说,本文提出了一种将Mori-Tanaka (M-T)均匀化模型和基于平均截距长度(MIL)形态学的方法相结合的微力学分析策略。初步分析考察了孔隙形状和分布对微观结构表征的影响,在某些情况下复 制了各向同性和各向异性条件。事实证明,无论孔隙度如何,MIL对微观结构取向分析都是有效的。随后,采用M-T方法估算杨氏模量,并研究其与孔隙形状、取向和体积分数的关系。这项对杨氏模量的调查提供了宝贵的见解,以揭示非均质材料中微观结构特征和宏观特性之间的复杂关系。本文提出的总体框架有望在实际应用中使用微ct图像预测真实材料的性能,有助于更深入地了解这些复杂材料及其行为。
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.
结合纤维增强复合材料的超材料、多阶段变形和高强度等优点,提出并制备了一种具有优异力学性能的新型花瓣状结构。首先对三种不同角度的纤维增强复合材料花瓣状结构进行了压缩试验和有限元分析。研究结果表明,通过合理的结构设计,这些复合材料基多胞结构也可以表现出令人满意的应力平台阶段。在保证结构在准静态压缩载荷下的性能后,进一步研究了新结构的抗冲击性能。结果表明,在低速冲击载荷作用下,结构的消声特性有所降低。在20J冲击荷载作用下,结构的能量吸收特性(SEA)是传统结构和其他新型减震结构的8 ~ 40倍。这些有希望的结果表明,新设计的花瓣状结构在建筑和汽车工业等各个领域具有很高的应用潜力。
Design and demonstration of a roll-out membrane antenna based on thin-walled deployable composite booms
Chao Xie, Zhiyi Wang, Yu Liu, Feng Gao, Li Qin, Jinping Yang, Fujun Peng, Wujun Chen
doi:10.1016/j.tws.2024.112486
基于薄壁可展开复合臂的展开膜天线设计与论证
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.
薄壁可展开复合材料臂架(DCB)具有高展开包封比和弹性自发展等优点,是航空轻量化结构领域的研究热点。提出了一种基于dcb的滚动膜天线(ROMA)的结构设计和性能论证。首先,建立了ROMA框架结构近似基频的简化解析算法,并根据构型设计参数研究了两类框架结构的一阶扭转模态振型。然后,比较估计了ROMA框架的弯曲、摆动和两种不同的扭转基频。此外,通过假设薄膜结构的简化质量分布模型,研究了薄膜阵列的平衡张力对ROMA结构弯曲基频的影响。最后,将简化的解析算法应用于AIS/VDE(自动识别系统/甚高频数据交换系统)ROMA的结构设计,并通过数值模拟和地面试验验证了其性能。AIS/VDE ROMA在浦江二号卫星上的成功部署和运行,进一步证明了薄壁dcb在航天领域的实际应用意义。
BPNN-based prediction for the shapes of a petal hole induced by hydrodynamic ram
Kerong Ren, Wenwen Wang, Hua Qing, Yong Peng, Wentao Xu, Zongkai He, Xiangyu Li, Fangyun Lu
doi:10.1016/j.tws.2024.112488
基于bpnn的水动力撞击器花瓣孔洞形状预测
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.
弹丸在液体中运动时的姿态角是影响充液结构在水动力撞击下发生动力破坏的重要因素。采用三维数字图像相关、有限元仿真和反向传播神经网络(BPNN)技术,研究了圆柱弹丸姿态角对煤油罐后板花瓣孔形状的影响。表征花瓣孔形状的倾角λ与弹丸撞击后板时的投影形状有关。花瓣孔形状的形成还伴随着后板塑性铰线的形成。此外,提出了一种结合bp神经网络和物理方程的方法,可以准确地预测弹丸在液体中的阻力系数和运动。在两个初始姿态角的二维空间中,给出了描述花瓣孔形状的函数。研究结果有助于了解液体进入过程中的轨迹稳定性,并有助于预测由HRAM引起的充液罐的动态失效模式。
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.
薄壁结构通常依靠冷弯低碳钢型材。由于冷成形,残余应力的显著形成影响其整体疲劳行为。在这项工作中,提出了一个最先进的疲劳寿命预测框架,并将其应用于滚动成形和冲压制动的全尺寸型材。最后,对型材的加工过程进行了数值模拟,得到了具有代表性的残余应力场。这些结果随后被用作后续结构和疲劳分析的初始状态。验证了明显的有害残余应力效应。然而,重要的是要注意,当考虑到这些影响时,预测的准确性会显著提高。