今日更新:International Journal of Solids and Structures 1 篇,Journal of the Mechanics and Physics of Solids 2 篇,International Journal of Plasticity 1 篇,Thin-Walled Structures 4 篇
Toughening mechanisms and damage propagation in Architected-Interfaces
Michelle L.S. Hedvard, Marcelo A. Dias, Michal K. Budzik
doi:10.1016/j.ijsolstr.2023.112600
结构化界面中的增韧机制和损伤传播
We investigate fracture toughness of architected interfaces and their ability to maintain structural integrity and provide stable damage propagation conditions beyond the failure load. We propose theoretical and numerical frameworks to evaluate the fracture properties of architected interfaces sandwiched between two (face) materials. The microscopic geometries of these interfaces are chosen as 2D cells—pillar, tetrahedron, and hexagon—as well as their 3D counterparts—namely, pillar array, octet truss, and Kelvin cell. Our model, both numerical and analytical, exhibits a high level of accuracy in predicting the compliance before failure and failure loads. Novel results are obtained during the damage propagation regime, indicating fulfilment of the so-called fail-safe design. Some of the cell geometries unfold during fracture, thus increasing the failure load and ensuring stable and controlled damage propagation conditions.
我们研究了拱形界面的断裂韧性及其保持结构完整性的能力,以及在破坏载荷之外提供稳定破坏传播条件的能力。我们提出了理论和数值框架来评估夹在两种(面)材料之间的拱形界面的断裂特性。这些界面的微观几何形状被选择为二维单元--柱体、四面体和六面体,以及它们的三维对应物--即柱体阵列、八面体桁架和开尔文单元。我们的数值和分析模型在预测破坏前的顺应性和破坏载荷方面都表现出很高的准确性。在破坏传播过程中获得了新的结果,表明实现了所谓的故障安全设计。一些电池的几何形状在断裂过程中展开,从而增加了破坏载荷,确保了稳定和受控的破坏传播条件。
A macroscopic viscoelastic viscoplastic constitutive model for porous polymers under multiaxial loading conditions
Martijn Wismans, Johannes A.W. van Dommelen, Tom A.P. Engels, Lambèrt C.A. van Breemen
doi:10.1016/j.jmps.2023.105499
多轴加载条件下多孔聚合物的宏观粘弹性粘塑结构模型
A macroscopic constitutive model, the Porous Eindhoven Glass Polymer (Porous EGP) model, is presented to describe the deformation behavior of cavitated rubber toughened polymers under multiaxial loading conditions. It is shown that the proposed macroscopic constitutive model is able to describe the non-linear pre-yield regime, strain rate dependence, post-yield behavior (strain softening and hardening) and void evolution for loading conditions ranging from shear to equi-triaxial (pure triaxial) tension and compression. The Porous EGP model is a combination of a well established non-linear viscoelastic viscoplastic model, the Eindhoven Glassy Polymer (EGP) model, and the modified Gurson model. The Gurson model is adopted to determine the equivalent stress and plastic rate of deformation tensor making it depending on the void volume fraction, deviatoric and hydrostatic stress. The macroscopic constitutive model is developed based on the response of realistic 3D representative volume elements (RVEs) containing randomly positioned mono-disperse inclusions. The constitutive behavior of the matrix phase in this full-field model is described by the EGP model, and the cavitated inclusions are idealized as voids. Their response is studied for a range of void volume fractions, multiaxial loading conditions, strain rates and thermodynamic states. The yield behavior of the heterogeneous material depends non-linearly on the macroscopic hydrostatic stress. This response is well captured with the proposed macroscopic constitutive model.
本文提出了一种宏观构成模型--多孔埃因霍温玻璃聚合物(Porous EGP)模型,用于描述多轴加载条件下空穴橡胶增韧聚合物的变形行为。研究表明,所提出的宏观构成模型能够描述从剪切到等三轴(纯三轴)拉伸和压缩等加载条件下的非线性屈服前机制、应变速率依赖性、屈服后行为(应变软化和硬化)以及空洞演化。多孔 EGP 模型是一个成熟的非线性粘弹性粘塑模型、埃因霍温玻璃聚合物 (EGP) 模型和改进的 Gurson 模型的组合。Gurson 模型用于确定等效应力和塑性变形率张量,使其取决于空隙体积分数、偏差应力和静水压力。宏观构成模型是根据包含随机定位的单分散夹杂物的现实三维代表体积元素(RVE)的响应建立的。该全场模型中基体相的构成行为由 EGP 模型描述,空化夹杂物被理想化为空隙。研究了一系列空隙体积分数、多轴加载条件、应变率和热力学状态下的响应。异质材料的屈服行为非线性地取决于宏观静水压力。所提出的宏观构成模型很好地捕捉到了这一响应。
Fluid-driven slow slip and earthquake nucleation on a slip-weakening circular fault
Alexis Sáez, Brice Lecampion
doi:10.1016/j.jmps.2023.105506
滑动减弱环形断层上的流体驱动慢滑动和地震成核问题
We investigate the propagation of fluid-driven fault slip on a slip-weakening frictional interface separating two identical half-spaces of a three-dimensional elastic solid. Our focus is on axisymmetric circular shear ruptures as they capture the most essential aspects of the dynamics of unbounded ruptures in three dimensions. In our model, fluid-driven aseismic slip occurs in two modes: as an interfacial rupture that is unconditionally stable, or as the quasi-static nucleation phase of an otherwise dynamic rupture. Unconditionally stable ruptures progress through four stages. Initially, ruptures are diffusively self-similar and the interface behaves as if it were governed by a constant friction coefficient equal to the static friction value. Slip then accelerates due to frictional weakening while the cohesive zone develops. Once the latter gets properly localized, a finite amount of fracture energy emerges along the interface. The rupture dynamics is then governed by an energy balance of the Griffith’s type. In this stage, fault slip transitions from a large-toughness to a small-toughness regime due to the diminishing effect of the fracture energy in the near-front energy balance. Ultimately, self-similarity is recovered and the fault behaves again as having a constant friction coefficient, but this time equal to the dynamic friction value. This condition is equivalent to a fault interface operating to leading order with zero fracture energy. When slow slip is the result of a frustrated dynamic instability, slip also initiates self-similarly at a constant peak friction coefficient. The maximum size that aseismic ruptures can reach before becoming unstable can be as small as a critical nucleation radius (shear modulus divided by the slip-weakening rate) and as large as infinity when faults are close to the limit that separates the two modes of aseismic sliding. In the former scenario, earthquake nucleation occurs unaffected by the dynamic friction coefficient. In contrast, the latter scenario exhibits fracture-mechanics behavior, characterized by a finite influx of elastic strain energy being supplied to and dissipated at the rupture front. We provide analytical and numerical solutions for the problem solved over its full dimensionless parameter space, including expressions for relevant length and time scales characterizing the transition between different stages and regimes. Due to its three-dimensional nature, the model enables quantitative comparisons with field observations as well as preliminary engineering design of hydraulic stimulation operations. Existing laboratory and in-situ experiments of fluid injection are briefly discussed in light of our results.
我们研究了流体驱动的断层滑移在分隔三维弹性实体两个相同半空间的滑移减弱摩擦界面上的传播。我们的重点是轴对称圆形剪切断裂,因为它们捕捉到了三维无 界断裂动力学的最基本方面。在我们的模型中,流体驱动的地震滑动有两种模式:一种是无条件稳定的界面破裂,另一种是动态破裂的准静态成核阶段。无条件稳定的破裂会经历四个阶段。最初,断裂是扩散性自相似的,界面的行为就像受等于静摩擦系数的恒定摩擦系数支配一样。然后,由于摩擦力减弱,滑动加速,同时形成内聚区。一旦内聚区适当局部化,就会沿界面产生有限的断裂能。随后,断裂动态受格里菲斯型能量平衡的支配。在这一阶段,由于近前能量平衡中断裂能量的递减效应,断层滑移从大韧性机制过渡到小韧性机制。最终,自相似性得到恢复,断层再次表现为具有恒定的摩擦系数,但此时的摩擦系数等于动摩擦值。这种情况相当于断层界面以领先阶运行,断裂能量为零。当缓慢滑动是受挫动不稳定性的结果时,滑动也会以恒定的峰值摩擦系数自类似地开始。地震断裂在变得不稳定之前所能达到的最大尺寸可以小到临界成核半径(剪切模量除以滑动减弱率),而当断层接近将两种地震滑动模式分开的极限时,则可以大到无穷大。在前一种情况下,地震成核不受动态摩擦系数的影响。相比之下,后一种情况则表现出断裂力学行为,其特征是有限的弹性应变能流入破裂前沿并在破裂前沿耗散。我们提供了该问题在其全无量纲参数空间内的分析和数值解决方案,包括相关长度和时间尺度的表达式,这些表达式表征了不同阶段和状态之间的过渡。由于该模型具有三维性质,因此可以与现场观测结果进行定量比较,并对水力激发作业进行初步工程设计。根据我们的研究结果,对现有的实验室和现场注液实验进行了简要讨论。
Crystal plasticity modeling of electropulsing induced plasticity in metals
Yang Yang, Rongshan Qin, Yalin Dong, Jian Wang, Chang Ye
doi:10.1016/j.ijplas.2023.103828
电脉冲诱导金属塑性的晶体塑性模型
A crystal plasticity model incorporating the effects of magnetoplasticity, electron-wind, imbalance of charges near grain boundaries and Joule heating in high frequency short duration electric current pulsed metals has been developed for metals with a face center cubic (FCC) structure. The model decouples the athermal and thermal effects on dislocation activity and quantifies their effects on flow stress. The Joule heating affects the thermal activation in plastic deformation. The magnetoplasticity and electron-wind reduce the slip barrier or contribute additional force to assist dislocation motion. Imbalance of charges near grain boundaries may amplify or minimize the contribution of thermal or other athermal effects. The developed crystal plasticity model has been implemented in DAMASK and verified by simulating electroplasticity in aluminum. The results reveal that the magnetoplasticity reduces flow stress and the reduction increases with the peak current density. Joule heating is generally less important during the processing due to the short pulse duration but becomes more significant when the frequency goes up. The impact of imbalance of charges near grain boundaries on Joule heating depends on the thickness of grain boundaries, the distribution of current density and conductivity, while it always reduces the effect on magnetoplasticity. The electron-wind effect on flow stress is negligible compared to the other three factors. This work provides some new insights in the understanding of electroplasticity in metals.
针对具有面心立方(FCC)结构的金属,我们开发了一种晶体塑性模型,其中包含了磁塑性、电子风、晶界附近电荷不平衡以及高频短时脉冲电流金属中焦耳热的影响。该模型将差排活动的非热效应和热效应分离开来,并量化了它们对流动应力的影响。焦耳加热影响塑性变形中的热激活。磁塑性和电子风降低了滑移障碍或提供了额外的力来帮助差排运动。晶界附近的电荷失衡可能会放大或缩小热效应或其他非热效应的贡献。开发的晶体塑性模型已在 DAMASK 中实施,并通过模拟铝的电塑性得到验证。结果显示,磁塑性降低了流动应力,且降低幅度随峰值电流密度的增加而增大。在加工过程中,由于脉冲持续时间较短,焦耳热一般不太重要,但当频率升高时,焦耳热变得更加重要。晶界附近电荷不平衡对焦耳加热的影响取决于晶界厚度、电流密度分布和电导率,而对磁塑性的影响总是减弱。与其他三个因素相比,电子风对流动应力的影响可以忽略不计。这项研究为理解金属中的电塑性提供了一些新的见解。
Static behavior of corrugated steel-shotcrete composite arches
Zhanming Wu, Yuyin Wang, Yong Mei, Faqi Liu, Changyong Liu
doi:10.1016/j.tws.2023.111429
波纹钢-混凝土复合拱的静态行为
A new type of corrugated steel-shotcrete composite (CSSC) arch is proposed, which possesses the advantages of both high load-bearing capacity and ease of construction. Thus it is particularly suitable for bridges, culverts, shafts, and other projects. In this study, the static behavior of the CSSC arch under three-point loading was investigated experimentally and numerically. Four specimens with different rise-span ratios (1/2, 1/8), different spans (3m, 6m), and different locations of shotcrete lining (shotcrete outer lining, shotcrete inner lining) were tested. The test results show that the load-bearing capacity and initial stiffness of the CSSC arch could reach 6.8 times and 13.9 times that of the corrugated steel (CS) arch, respectively. When the load was less than 0.4 times the load-bearing capacity of the specimens, CS and shotcrete worked together. After that, the composite effect between CS and shotcrete was weakened. The ductility of the shotcrete outer lining CSSC arch is better than that of the shotcrete inner lining CSSC arch. A finite element model (FEM) was developed to investigate the influences of key parameters on the load-bearing capacity, including the thickness of materials, the strength of materials, the rise-span ratios and spans. Furthermore, calculation methods were proposed to predict the axial compressive capacity of the CSSC arch.
本文提出了一种新型波纹钢-混凝土复合拱(CSSC),它具有承载能力高、施工简便等优点。因此,它特别适用于桥梁、涵洞、竖井等工程。本研究采用实验和数值方法研究了 CSSC 拱在三点荷载作用下的静态行为。测试了四个不同升跨比(1/2、1/8)、不同跨度(3 米、6 米)和不同喷射混凝土衬砌位置(喷射混凝土外衬、喷射混凝土内衬)的试件。试验结果表明,中船重工拱桥的承载力和初始刚度分别达到波纹钢拱桥的 6.8 倍和 13.9 倍。当荷载小于试件承载力的 0.4 倍时,CS 和喷射混凝土 共同起作用。之后,CS 和喷射混凝土的复合效应减弱。喷射混凝土外衬 CSSC 拱桥的延性优于喷射混凝土内衬 CSSC 拱桥。为研究材料厚度、材料强度、升跨比和跨度等关键参数对承载能力的影响,建立了有限元模型(FEM)。此外,还提出了预测 CSSC 拱桥轴向抗压能力的计算方法。
Mechanics and Validation Tests of a Post-Tensioned Self-Centering Brace with Adjusted Stiffness and Deformation Capacities Using Disc Springs
Chung-Che Chou, Li- Yu Huang
doi:10.1016/j.tws.2023.111430
利用碟形弹簧调整刚度和变形能力的后张自定心支撑的力学性能和验证试验
Self-centering braces have been developed to reduce the residual deformation of steel frames in earthquakes. The brace has a higher elastic axial stiffness before the activation, which may result in a higher base shear for frame design. This work was aimed to develop a new post-tensioned self-centering brace (PT-SCB) with adjusted stiffness and deformation capabilities such that the brace could be designed based on a specified yield or ultimate frame drift. Combining disc springs and one of the compression members together in the original SCB could achieve new structural characteristics, providing an alternative to tune the axial stiffness and deformation. This work first introduces the mechanics and deformation mechanism of the proposed SCB and performs a parametric study to investigate the effect of disc spring stacks on the hysteretic response of SCBs. A test program is then conducted on cyclic tests of disc spring stacks in different serial and parallel combinations and two PT-SCBs. Each 3800 mm-long brace is composed of high-strength steel tendons, compression steel members, disc spring stacks, and bolted friction device. The hysteretic responses of the new SCB with different design parameters are used to validate the mechanics and ability of the axial stiffness and deformation adjustment.
自定心支撑的开发是为了减少钢框架在地震中的残余变形。自定心支撑在启动前具有较高的弹性轴向刚度,这可能会导致框架设计的基础剪力增大。这项工作的目的是开发一种新型后张法自定心支撑(PT-SCB),它具有调整刚度和变形能力,可以根据指定的屈服或极限框架漂移进行设计。将碟形弹簧和原 SCB 中的一个压缩构件组合在一起可实现新的结构特性,为调整轴向刚度和变形提供了另一种选择。本研究首先介绍了拟议 SCB 的力学和变形机理,并进行了参数研究,以探讨碟形弹簧叠层对 SCB 滞后响应的影响。然后,对不同串联和并联组合的碟形弹簧组和两个 PT-SCB 进行了循环测试。每个 3800 毫米长的支撑由高强度钢筋、压缩钢构件、碟形弹簧组和螺栓摩擦装置组成。采用不同设计参数的新型 SCB 的滞后响应验证了轴向刚度和变形调整的力学性能和能力。
Fatigue crack growth and life assessment of full penetration U-rib welded joints considering residual stresses
Hao Zheng, Zhiyu Jie, Lexin Zhang, Wei Lu
doi:10.1016/j.tws.2023.111426
考虑残余应力的全熔透 U 形肋焊接接头的疲劳裂纹增长和寿命评估
The combination of cyclic stresses and welding residual stresses (WRS) can significantly contribute to fatigue cracking in steel bridge decks. This study aims to investigate the effect of WRS on the fatigue life and crack propagation of single-sided and full penetration double-sided U-rib welded joints through experimental and numerical methods. Fatigue tests were conducted to study fatigue crack initiation and propagation behavior. Utilizing the ABAQUS software, a thermoelastic-plastic finite element method was employed to determine the residual stress distribution. Subsequently, based on linear elastic fracture mechanics (LEFM), fatigue crack propagation and life assessment were performed using ABAQUS and FRANC3D software under the coupling of residual stresses and external cyclic stresses. Findings reveal that WRS play a crucial role in fatigue life by altering the effective stress ratio during fatigue crack growth. The effective stress ratio ranges from 0.15 to 0.57, while the changing trends differ between single-sided and double-sided U-rib welded joints. The fatigue crack growth rate of double-sided U-rib welded joints is lower compared to single-sided U-rib welded joints with the same deck thickness. Furthermore, the introduction of WRS induces a mixed mode I, II, and III fracture at the outer weld toe of the U rib, with mode I fracture predominating, which leads to a deviation in the crack propagation path. The fatigue life prediction results agree well with experimental findings when considering WRS. Importantly, these predictions tend to be conservative, thereby ensuring safety and reliability in engineering applications.
循环应力和焊接残余应力(WRS)的共同作用会显著导致钢桥面的疲劳开裂。本研究旨在通过实验和数值方法研究 WRS 对单面和全熔透双面 U 形肋焊接接头的疲劳寿命和裂纹扩展的影响。通过疲劳试验研究了疲劳裂纹的起始和扩展行为。利用 ABAQUS 软件,采用热弹塑性有限元法确定了残余应力分布。随后,基于线性弹性断裂力学(LEFM),使用 ABAQUS 和 FRANC3D 软件在残余应力和外部循环应力的耦合下进行了疲劳裂纹扩展和寿命评估。研究结果表明,WRS 通过改变疲劳裂纹生长过程中的有效应力比,对疲劳寿命起着至关重要的作用。有效应力比从 0.15 到 0.57 不等,而单面和双面 U 形肋焊接接头的变化趋势各不相同。与相同桥面厚度的单面 U 形肋焊接接头相比,双面 U 形肋焊接接头的疲劳裂纹增长速率较低。此外,WRS 的引入在 U 形肋外焊趾处诱发了 I、II 和 III 三种模式的混合断裂,其中以 I 模式断裂为主,这导致了裂纹扩展路径的偏差。当考虑到 WRS 时,疲劳寿命预测结果与实验结果非常吻合。重要的是,这些预测结果趋于保守,从而确保了工程应用的安全性和可靠性。
Experimental and numerical investigations of a novel parallel double-stage crawler-track-shaped shear damper
Cantian Yang, Linlin Xie, Qiang Liu, Aiqun Li, Xinyu Wang, Qianmin Liu
doi:10.1016/j.tws.2023.111428
新型平行双级履带式剪切阻尼器的实验和数值研究
In this study, a novel parallel double-stage crawler-track-shaped shear damper (PDCSD) was developed, which is fabricated using thin-walled steel plates. An asynchronized double-stage working mechanism was achieved based on the parallel energy dissipation (inner and outer crawler-track-shaped steel plates), restraining (upper and lower restraining plates), and load transfer (outer and inner blockers with initial clearance) systems. Accordingly, theoretical equations for the skeleton curve of the PDCSD and the design load for the load transfer system were proposed. The double-stage working mechanism and performance of the PDCSD were verified based on full-scale seismic and fatigue performance tests. Subsequently, based on refined finite element analyze, the working mechanism of the PDCSD was revealed and the theoretical equations were validated. A simplified model of the PDCSD with an emphasize on the hysteretic behavior was conclusively recommended and validated against the test and simulation results obtained from the refined numerical models, providing an accurate and efficient approach for the seismic response control of structures equipped with PDCSDs.
本研究开发了一种新型平行双级履带式剪切阻尼器(PDCSD),采用薄壁钢板制造。在平行消能(内、外履带式钢板)、约束(上、下约束板)和载荷传递(具有初始间隙的外、内阻挡块)系统的基础上,实现了不同步双级工作机制。据此,提出了 PDCSD 的骨架曲线和载荷传递系统设计载荷的理论方程。基于全尺寸抗震和疲劳性能试验,对 PDCSD 的双级工作机制和性能进行了验证。随后,基于精细的有限元分析,揭示了 PDCSD 的工作机理并验证了理论方程。根据细化数值模型获得的试验和模拟结果,最终推荐并验证了一种侧重于滞后行为的 PDCSD 简化模型,为配备 PDCSD 的结构的地震响应控制提供了一种准确而有效的方法。