今日更新:International Journal of Solids and Structures 1 篇,Journal of the Mechanics and Physics of Solids 1 篇,Mechanics of Materials 1 篇,Thin-Walled Structures 4 篇
Crack initiation and propagation from a closing flaw with frictional contact in a natural quasi-brittle orthotropic solid
Sailendu Biswal, Gaurav Singh
doi:10.1016/j.ijsolstr.2024.112989
天然准脆正交各向异性固体中具有摩擦接触的闭合裂纹的裂纹萌生和扩展
This work considers the frictional closing of a pre-existing flaw in a natural quasi-brittle orthotropic medium (wood) under compression. The effect of the flaw face friction at multiple orientations of the flaw, on the peak load-bearing capacity are investigated. The failure due to crack growth initiation from the periphery of the pre-existing flaw and its propagation was investigated experimentally and modeled numerically. The experimental investigation was carried out using New Zealand Pine wood with a pre-existing flaw under a quasi-static compression test. In the numerical investigation, an eXtended finite element (XFEM)-based cohesive zone model (CZM) is employed in the modeling of the local crack initiation and propagation. The onset of the crack initiation is modeled using a stress-based criterion and the progressive degradation due to crack propagation is traction-separation based damage evolution. The XFEM-based CZM captures the crack initiation and propagation well consistent with the experimental results. The numerical results also show the impact of flaw face friction on the peak load bearing capacity as well as the local stress response.
这项工作考虑了在压缩下天然准脆性正交各向异性介质(木材)中预先存在缺陷的摩擦关闭。研究了裂纹面多方向摩擦对裂纹峰值承载能力的影响。通过实验和数值模拟研究了由裂纹扩展引发的破坏及其扩展过程。采用带缺陷的新西兰松木进行准静态压缩试验。在数值研究中,采用基于扩展有限元(XFEM)的黏聚区模型(CZM)来模拟局部裂纹的萌生和扩展。裂纹的起裂采用基于应力的准则进行建模,裂纹扩展的逐步退化是基于牵引分离的损伤演化。基于xfem的CZM能较好地捕捉到裂纹的萌生和扩展过程,与实验结果吻合较好。数值结果还显示了缺陷面摩擦对峰值承载能力和局部应力响应的影响。
A simple hydrodynamic model for clay
Max Wiebicke, Itai Einav
doi:10.1016/j.jmps.2024.105789
粘土的简单水动力模型
Laboratory description of clay normally distinguishes the scale of atoms from the scale of clay particles and aggregates. Contemporary constitutive models for clay tend to ignore this scale separation, and rather focus on phenomenology. By considering scale separation, this paper introduces a robust physics-based phenomenological constitutive model for clay that qualitatively captures their broad spectrum of rate-dependent mechanical features. The model is derived using the thoroughly rigorous hydrodynamic procedure. While some imagine that by considering rigour and physics, their models would get complicated, the resulting set of equations reveal a surprising degree of simplicity. The derivation strongly benefits from the principle of two-stage irreversibility, which describes energy flow within the material from the continuum scale down to the atomistic micro-scale, through the meso-scale of clay aggregates. While thermal and meso-related temperatures capture atomistic and clay aggregate fluctuating motions, a sink term from the latter to the former underpins the direction of the energy flow. The model’s standout feature is in pinpointing new transport coefficients that drive both volumetric and shear plastic flows in a thermodynamically coupled manner. A novel scheme is then proposed to calibrate these coefficients from conventional steady-state observations. Thanks to the formulation the model shows a remarkable level of predictiveness, despite being relatively simple mathematically. In particular, the model can readily explain the broad spectrum of rate-dependent phenomena during transient loading, along with creep and relaxation processes. Given the generality of hydrodynamics, it is anticipated that the new model could be expanded to capture fluid-solid transitions between liquid-like soft mud and plastic-like stiff clay responses, contingent on water content variations.
实验室对粘土的描述通常将原子尺度与粘土颗粒和聚集体的尺度区分开来。当代粘土本构模型倾向于忽略这种尺度分离,而更注重现象学。通过考虑尺度分离,本文引入了一个健壮的基于物理的粘土现象学本构模型,该模型定性地捕获了它们的广谱速率相关的力学特征。该模型是用完全严格的流体力学程序推导出来的。虽然有些人认为,考虑到严格性和物理学,他们的模型会变得复杂,但最终的一组方程显示出惊人的简单程度。该推导得益于两阶段不可逆性原理,该原理描述了材料内部从连续体尺度到原子微观尺度,通过粘土聚集体的中观尺度的能量流动。当热和中观相关的温度捕获原子和粘土集 合体的波动运动时,从后者到前者的汇项支撑着能量流的方向。该模型的突出特点是确定了新的输运系数,这些系数以热力学耦合的方式驱动体积和剪切塑性流动。然后提出了一种新的方案来校准这些系数从传统的稳态观测。尽管在数学上相对简单,但由于这个公式,这个模型显示出了显著的预测性。特别是,该模型可以很容易地解释瞬态加载过程中与速率相关的广谱现象,以及蠕变和松弛过程。考虑到流体力学的普遍性,预计新模型可以扩展到捕获流体-固体之间的过渡,类液体软泥和类塑料硬粘土响应,取决于含水量的变化。
Contributing Factors to Preterm Pre-Labor Rupture of The Fetal Membrane: Biomechanical Analysis of The Membrane Under Different Physiological Conditions
Daniel S. Fidalgo, Kayvan Samimi, Melissa C. Skala, Renato M.N. Jorge, Marco P.L. Parente, Ewelina Malanowska, Kristin M. Myers, Dulce A. Oliveira
doi:10.1016/j.mechmat.2024.105104
早产胎膜产前破裂的影响因素:不同生理条件下胎膜的生物力学分析
The fetal membranes are a complex biological structure essential for pregnancy, comprising two main layers: the amnion and the chorion. Characterizing each layer from a mechanical perspective is extremely important to understand the rupture process of the membrane at term or preterm. It is still unclear what factors lead to preterm pre-labor rupture of the membrane (PPROM) due to ethical and technical factors associated with in-vivo experimental tests. Numerical simulations may offer some answers, clarifying the biomechanics of the fetal membrane during gestation. This work uses a validated multilayer fetal membrane model to evaluate whether certain physiological conditions occurring during pregnancy contribute to PPROM. The following factors are evaluated: (i) contact conditions between the amnion and the chorion, (ii) normal and abnormal intrauterine pressures, (iii) amnion and chorion thicknesses, and (iv) orientation of the collagen fibers within the amnion layer. Our results show that PPROM might be potentiated under certain physiological circumstances: (i) the existence of interconnection (friction or tied contact) between the two main layers of the fetal membrane increases the stress in the mechanical dominant amnion, (ii) larger intrauterine pressures and (iii) smaller amnion and chorion thicknesses lead to the same increase in stress, and (iv) different off-plane angles of the collagen fibers tend to modify the stress distribution and thickness variation in both layers.
胎膜是一个复杂的生物结构,对怀孕至关重要,包括两层:羊膜和绒毛膜。从力学角度描述每一层对于理解足月或早产时膜的破裂过程是非常重要的。由于与体内实验测试相关的伦理和技术因素,目前尚不清楚是什么因素导致早产产前膜破裂(PPROM)。数值模拟可能提供一些答案,澄清胎膜在妊娠期间的生物力学。这项工作使用了一个经过验证的多层胎膜模型来评估怀孕期间发生的某些生理状况是否会导致PPROM。评估以下因素:(i)羊膜和绒毛膜之间的接触条件,(ii)正常和异常的宫内压力,(iii)羊膜和绒毛膜厚度,(iv)羊膜层内胶原纤维的方向。我们的研究结果表明,在一定的生理条件下,PPROM可能会被增强:(1)胎膜两主要层之间相互连接(摩擦或捆绑接触)的存在增加了机械优势羊膜中的应力,(2)较大的宫内压力和(3)较小的羊膜和绒毛膜厚度导致应力增加相同,(4)胶原纤维的不同离面角度倾向于改变两层的应力分布和厚度变化。
Spectral element-finite element modeling and dynamic analysis of a fluid-delivering cracked pipe subjected to both pulsation and base excitations
Wenhao Ji, Hongwei Ma, Honghao Liu, Wei Sun, Donghai Wang
doi:10.1016/j.tws.2024.112242
谱元-有限元建模及受脉动和基底激励的输液管的动力学分析
Previous studies on cracked pipes have predominantly focused on single excitation, but in practical engineering, pipe systems often experience a combined effect of fluid pulsation and base excitations, which can potentially trigger more complex dynamic behaviors. Moreover, the solid finite element (FE) models are generally adopted to simulate the breathing effect and stress singularity, but the solution efficiency is unacceptable. Therefore, this study presents a spectral element-finite element (SE-FE) method to construct the dynamic models of the fluid-delivering cracked pipes (FDCPs), which combines the efficiency of spectral element (SE) with the adaptability of FE. Furthermore, a fluid pulsation model is constructed using measured data. Specifically, dynamic models of intact and cracked pipe segments are constructed using SE and FE, respectively, and interface coupling is achieved by the penalty function method. Subsequently, an experimental system for fluid pulsation excitation is established, and then a fluid pulsation model is constructed. Finally, the dynamic behaviors of a FDCP under compound excitation are analyzed. The results show that the fluid pulsation in the FDCP is higher than that in the intact pipe due to the breathing effect. Moreover, the beat vibration will be triggered when the pulsation frequency approaches the base excitation frequency. This study can provide a better understanding for the dynamic behaviors of FDCP, thereby providing a reference for crack damage detection.
以往对裂纹管道的研究主要集中在单一激励上,但在实际工程中,管道系统经常会受到流体脉动和基底激励的综合影响,这可能会引发更复杂的动力行为。此外,通常采用实体有限元模型来模拟呼吸效应和应力奇点,但求解效率令人难以接受。为此,本研究提出了一种结合谱元(SE)效率和有限元适应性的谱元-有限元(SE-FE)方法来构建输液裂纹管道(fdps)的动力学模型。利用实测数据建立了流体脉动模型。其中,完整管段和裂纹管段分别采用SE和FE建立动力模型,并采用罚函数法实现界面耦合。在此基础上,建立了流体脉动激励实验系统,建立了流体脉动模型。最后,分析了FDCP在复合激励下的动态特性。结果表明,由于呼吸效应的影响,FDCP管内的流体脉动比完整管道内的流体脉动要大。当脉动频率接近基激励频率时,将触发脉动振动。该研究可以更好地了解FDCP的动态行为,从而为裂纹损伤检测提供参考。
A data-driven computational optimization framework for designing thin-walled lenticular deployable composite boom with optimal load-bearing and folding capabilities
Junwei Sun, Qigang Han, Xianhe Cheng, Hexuan Shi, Rundong Ding, Mingdi Shi, Chunguo Liu
doi:10.1016/j.tws.2024.112244
具有最佳承载和折叠能力的薄壁透镜可展开复合材料臂设计的数据驱动计算优化框架
The thin-walled lenticular deployable composite boom (LDCB) is promising for aerospace engineering applications due to its lightweight and compact nature, but its mechanical behaviors are the main challenges limiting its practical application. Here, the axial compression and folding behaviors of LDCB were numerically simulated and the simulation results were verified according to the experimental data in the literature. Then, a new double chains quantum genetic algorithm (DCQGA)-gaussian process regression (GPR) model and data-driven computational optimization framework were proposed and the new model was trained using a database with 400 simulation results, the superiority of which was demonstrated by prediction accuracy evaluation. Additionally, benchmarking five state-of-the-art algorithms found that the coupling technology of DCQGA-GPR-non-dominated sorting genetic algorithm III (NSGA-III) is an excellent optimization strategy to obtain a well-designed structure of LDCB that maximizes the effectiveness of the material while satisfying the lightweight. The optimized LDCB design exhibits a significant performance improvement, with a 26.3% reduction in the folding moment, a 34.2% reduction in the maximum Tsai-Hill failure index, a 43.6% increase in the critical load, and an 11% reduction in linear density of mass compared to the initial design.
薄壁透镜式可展开复合材料臂架(LDCB)由于其轻量化和紧凑的特性,在航空航天工程中有着广阔的应用前景,但其力学性能是限制其实际应用的主要挑战。本文对LDCB的轴向压缩和折叠行为进行了数值模拟,并根据文献中的实验数据对模拟结果进行了验证。然后,提出了一种新的双链量子遗传算法(DCQGA)-高斯过程回归(GPR)模型和数据驱动的计算优化框架,并利用400个仿真结果的数据库对新模型进行了训练,通过预测精度评价证明了新模型的优越性。此外,对五种最先进的算法进行了基准测试,发现dcqga - gpr -非主导排序遗传算法III (NSGA-III)的耦合技术是一种优秀的优化策略,可以获得设计良好的LDCB结构,使材料的有效性最大化,同时满足轻量化。优化后的LDCB与初始设计相比,折叠弯矩降低了26.3%,最大Tsai-Hill破坏指数降低了34.2%,临界载荷提高了43.6%,质量线密度降低了11%。
Stability analysis of sandwich double nanobeam-system with varying cross-section interconnected by Kerr-type three-parameter elastic layer
M. Soltani, M.H. Momenian, O. Civalek
doi:10.1016/j.tws.2024.112249
克尔型三参数弹性层连接变截面夹层双纳米梁系统的稳定性分析
In this study, the endurable buckling load of the elastically connected parallel sandwich nano-beams with varying cross-sections is assessed. In this regard, a layered beam system consisting of two parallel axially loaded tapered sandwich nanobeams that are interconnected via a Kerr-type three-parameter elastic foundation is considered. The geometric properties are assumed to be changed exponentially along the length of the beam element. The governing equilibrium equations of the system are described by a set of three coupled homogeneous differential equations, which originates in the context of Eringen's non-local elasticity theory and Euler beam model. Then, the numerical differential quadrature technique is used to estimate the endurable axial critical loads. Eventually, a comprehensive parameterization research is performed to investigate the sensitivity of linear buckling resistance to tapering ratio, nonlocal parameter, stiffness of elastic connections, volume fraction exponent, and thickness ratio. The research work of the present study is novel, and the attained numerical outcomes can be used as benchmarks for future researches in this field.
在本研究中,评估了弹性连接的不同截面的平行夹层纳米梁的耐屈曲载荷。在这方面,考虑了由两个平行轴向加载的锥形夹层纳米梁组成的层状梁系统,这些纳米梁通过kerr型三参数弹性基础相互连接。假定几何性质沿梁单元长度呈指数变化。系统的控制平衡方程由三个耦合齐次微分方程来描述,该微分方程起源于Eringen的非局部弹性理论和欧拉梁模型。在此基础上,利用数值微分正交技术估算了轴向临界载荷。最后,进行了全面的参数化研究,探讨了线性屈曲抗力对锥度比、非局部参数、弹性连接刚度、体积分数指数和厚度比的敏感性。本文的研究工作是新颖的,所获得的数值结果可以作为该领域未来研究的基准。
Geometrically nonlinear analysis of plates and shells by a cell-based smoothed CS-MITC18+ flat shell element with drilling degrees of freedom
Thanh Chau-Dinh, Nghia Tran-Chi, Van-Hau Nguyen, Trung-Kien Nguyen
doi:10.1016/j.tws.2024.112254
基于网格光滑CS-MITC18+平面壳单元的板壳几何非线性分析
A development of a 3-node triangular flat shell element to analyze geometric nonlinearity of plate and shell structures is presented in this study. The proposed flat shell element has 6 degrees of freedom per node, including the drilling rotational ones, by using the Allman-type approximations for the in-plane displacements and the bending displacement approximations enriched by a cubic shape function at the bubble node located at the element's centroid. The geometrically nonlinear behaviors are described by the von Karman's large deflection assumption. The membrane and bending strains of the presented flat shell elements are averaged over sub-triangular elements based on the cell-based smoothed (CS) technique. To attenuate the shear locking phenomenon, the transverse shear strains are re-interpolated following the mixed interpolation of tensorial components (MITC) technique designed for the 3-node triangular degenerated shell elements enriched by a cubic bubble function (MITC3+). Combined with the Newton-Raphson iterations and load increments predicted by the arc-length method, the suggested 3-node triangular flat shell elements, namely the CS-MITC18+ element, can analyze moderately geometrical nonlinearity, including the snap-thought and snap-back behaviors, of various plates and shells with the different shapes, thickness, and boundaries. The numerical investigations show that the load-displacement curves provided by the CS-MITC18+ flat shell elements well agree with other references.
本文提出了一种用于板壳结构几何非线性分析的三节点三角形平壳单元。通过使用allman型面内位移近似和弯曲位移近似,所提出的平壳单元在单元质心处的气泡节点上丰富了三次形状函数,每个节点具有6个自由度,包括钻井旋转节点。几何非线性行为由von Karman大挠度假设描述。基于单元平滑(CS)技术,将平面壳单元的膜应变和弯曲应变平均到次三角形单元上。为了减弱剪切锁紧现象,采用基于三节点三角形退化壳单元的三次立方泡函数(MITC3+)的张量分量混合插值(MITC)技术对横向剪切应变进行了重新插值。结合弧长法预测的Newton-Raphson迭代和载荷增量,建议的3节点三角形扁平壳单元CS-MITC18+单元可以分析不同形状、厚度和边界的各种板壳的适度几何非线性,包括弹思和弹回行为。数值研究表明,CS-MITC18+平壳单元提供的荷载-位移曲线与其他文献吻合较好。