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【新文速递】2024年12月5日固体力学SCI期刊最新文章

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今日更新:International Journal of Solids and Structures 3 篇,Journal of the Mechanics and Physics of Solids 3 篇,Mechanics of Materials 1 篇,Thin-Walled Structures 5 篇

International Journal of Solids and Structures

Emergence of tension-compression asymmetry from a complete phase-field approach to brittle fracture

Chang Liu, Aditya Kumar

doi:10.1016/j.ijsolstr.2024.113170

从完全相场分析脆性断裂的拉压不对称性的出现

The classical variational approach to brittle fracture propagation does not distinguish between strain energy accumulation in tension versus compression and consequently results in physically unrealistic cracking under compression. A variety of energy splits have been proposed as a possible remedy. However, a unique energy split that can describe this asymmetry for general loading conditions has not been found. The main objective of this paper is to show that a complete phase-field theory of brittle fracture nucleation and propagation, one that accounts for the material strength at large, can naturally capture the tension-compression asymmetry without an energy split. One such theory has been recently proposed by Kumar et al. (2018). Over the past few years, several studies have shown that this theory is capable of accurately describing fracture nucleation and propagation for materials soft and hard under arbitrary monotonic loading conditions. However, a systematic study of the tension-compression asymmetry that emerges from this theory has not yet been reported. This paper does precisely that. In particular, this paper reports a comprehensive study of crack propagation in two problems, one involving a symmetric tension-compression state and the other involving larger compressive stresses at the crack tip. The results are compared with popular energy splits used in literature. The results show that, remarkably, for the second problem, only the complete theory is able to produce experimentally consistent results.

脆性断裂扩展的经典变分方法没有区分拉伸和压缩下的应变能积累,从而导致物理上不现实的压缩开裂。作为一种可能的补救措施,已经提出了各种各样的能源拆分。然而,一个独特的能量分裂,可以描述这种不对称的一般加载条件尚未发现。本文的主要目的是表明,一个完整的脆性断裂成核和扩展的相场理论,一个解释材料强度的理论,可以自然地捕捉拉压不对称而没有能量分裂。Kumar等人(2018)最近提出了一个这样的理论。近年来的一些研究表明,该理论能够准确地描述任意单调加载条件下软、硬材料的断裂形核和扩展。然而,从这一理论中产生的拉压不对称性的系统研究尚未被报道。本文正是这样做的。特别地,本文报道了两个问题中裂纹扩展的全面研究,一个涉及对称的拉压缩状态,另一个涉及裂纹尖端较大的压应力。结果与文献中常用的能量分割进行了比较。结果表明,值得注意的是,对于第二个问题,只有完整的理论才能产生与实验一致的结果。


Unified characterization of failure surfaces and golden-ratio ductile-to-brittle classification for isotropic materials

Sontipee Aimmanee, Pijak Tiraviriyaporn

doi:10.1016/j.ijsolstr.2024.113184

各向同性材料破坏面统一表征及黄金比例延脆分级

The failure surface, often referred to as the failure angle, defines the specific planar orientation within a material that reaches its load-carrying capacity, represented by material strengths. Analyzing this critical surface is elemental for material characterization, providing profound insights into ductility and brittleness. Despite the diversity of methodologies employed for determining the failure plane from various criteria, a universally accepted theory that systematically governs this characteristic across a broad spectrum of isotropic materials remains elusive. Therefore, this paper aims to develop a unified framework for predicting the failure surface for all homogeneous isotropic solids by considering the convergence of three key material constitutive models: elasticity, failure, and plasticity. A universal energy-based failure criterion is utilized to determine failure angles under fundamental loading scenarios, including uniaxial tension, uniaxial compression, pure shear, and biaxial tension–compression. The sliding, splitting, and crushing behaviors are obtained from the direct and shear strain increments, while the ratio of the two strain increments elucidates the dominant roles in ductile and brittle failure modes. For the first time, the developed theory links the failure angle to Poisson’s ratio, and uniaxial strength properties, unveiling a connection between intrinsic material parameters and extrinsic ductility and brittleness induced by external loadings. The failure angle representing ductile-to-brittle transition under the applied stresses in the principal stress coordinates is shown to be directly related to the golden ratio and independent of loading types. This research addresses longstanding mysteries by providing a deeper understanding of the physics of solids and suggesting potential applications with a phase-field model for predicting the evolving fracture direction.

破坏面,通常称为破坏角,定义了材料内部达到其承载能力的特定平面方向,用材料强度表示。分析这一关键表面是材料表征的基本要素,提供了对延展性和脆性的深刻见解。尽管从各种标准中确定破坏面所采用的方法多种多样,但在广泛的各向同性材料中系统地控制这一特性的普遍接受的理论仍然难以捉摸。因此,本文旨在通过考虑三个关键材料本构模型:弹性、破坏和塑性的收敛性,建立一个统一的框架来预测所有均质各向同性固体的破坏面。采用通用的基于能量的破坏准则来确定基本加载场景下的破坏角度,包括单轴拉伸、单轴压缩、纯剪切和双轴拉压缩。直接应变增量和剪切应变增量分别获得了岩石的滑动、劈裂和破碎行为,而两种应变增量的比值说明了在韧性破坏模式和脆性破坏模式中起主导作用。该理论首次将破坏角与泊松比和单轴强度特性联系起来,揭示了材料的内在参数与外部载荷引起的外在延性和脆性之间的联系。在主应力坐标下,表示韧性-脆性转变的破坏角与黄金比例直接相关,与加载类型无关。该研究通过提供对固体物理的更深入理解,并提出了相场模型预测裂缝方向演变的潜在应用,解决了长期存在的谜团。


A response surface function method to characterize residual stress and cumulative plastic strain through indentation

Hui Chen, Pascale Kanoute, Manuel François

doi:10.1016/j.ijsolstr.2024.113176

一种表征压痕残余应力和累积塑性应变的响应面函数法

Shot peening is a mechanical surface treatment used to improve the material fatigue performance by introducing compressive residual stress and work hardening. In order to characterize the residual stress (RS) and cumulative plastic strain (PS) of the treated surface simultaneously using the instrumented indentation technique, a Response Surface Function method is proposed in this work using a calibration by finite element simulations. The method is first verified numerically, and the results indicate that the determined values can accurately represent the input values, which shows the possibility of experimental application. The proposed method is then applied experimentally on a nickel-based alloy, Inconel 625. For validation, the solved profiles are compared with the profiles measured by X-ray diffraction (XRD). Although there is a difference between the profiles obtained by these two measurement techniques, the proposed method makes an advance on the characterization of residual stress and cumulative plastic strain simultaneously. It has demonstrated its feasibility, indicating its potential for practical application.

喷丸强化是一种机械表面处理,通过引入压缩残余应力和加工硬化来改善材料的疲劳性能。为了利用仪器压痕技术同时表征处理表面的残余应力(RS)和累积塑性应变(PS),本文提出了一种响应面函数法,采用有限元模拟校准。首先对该方法进行了数值验证,结果表明,所确定的数值能够准确地表示输入值,显示了实验应用的可能性。然后将该方法应用于镍基合金Inconel 625的实验中。为了验证,将解出的轮廓与x射线衍射(XRD)测量的轮廓进行了比较。虽然这两种测量方法得到的剖面存在差异,但所提出的方法在同时表征残余应力和累积塑性应变方面取得了进步。实验证明了该方法的可行性,表明了其实际应用的潜力。


Journal of the Mechanics and Physics of Solids

Phase field fracture in elastoplastic solids: a stress-state, strain-rate, and orientation dependent model in explicit dynamics and its applications to additively manufactured metals

Cunyi Li, Jian Liu, Le Dong, Chi Wu, Grant Steven, Qing Li, Jianguang Fang

doi:10.1016/j.jmps.2024.105978

弹塑性固体的相场断裂:显式动力学中的应力状态、应变速率和取向依赖模型及其在增材制造金属中的应用

Phase field models have gained growing popularity in analysing fracture behaviour of materials. However, few have been explored to simulate dynamic ductile fracture to date. This study aims to develop a phase field framework considering strain rate, stress state, and orientation dependent ductile fracture under dynamic loading. Firstly, governing equations of displacement and phase fields are formulated in an explicit finite element framework. Secondly, constitutive relations are established with a hypoelastic-plasticity framework, encompassing the influence of material orientation and strain rate on both plasticity and fracture initiation. Stress states dependent fracture initiation is also considered. Thirdly, finite element implementation and corotational formulation for constitutive equations are derived. To validate the proposed model, finally, additively manufactured samples, involving material-level and crack propagation specimens are tested under dynamic loading conditions. Overall, the proposed phase field model can properly reproduce the experimental force-displacement curves and crack paths. Uniaxial tension tests reveal that a higher strain rate can lead to a higher hardening curve and lower ductility. Other material specimens further demonstrate the capability to predict stress state and orientation dependent dynamic fracture. To simulate dynamic crack paths accurately, it is necessary to consider anisotropic fracture initiation. Lastly, the phase field model was applied for the first time to predict the dynamic response of triply periodic minimal surface (TPMS) structures. Dynamic crack patterns were effectively captured, and the fracture mechanisms were thoroughly analysed. This study provides an explicit phase field framework for dynamic ductile fracture, with applications to additively manufactured materials and structures.

相场模型在分析材料断裂行为方面得到了越来越广泛的应用。然而,迄今为止,模拟动态韧性断裂的方法还很少。本研究旨在建立考虑应变速率、应力状态和取向依赖的动态加载韧性断裂相场框架。首先,在显式有限元框架中建立了位移场和相场的控制方程。其次,在低弹塑性框架下建立本构关系,考虑材料取向和应变速率对塑性和断裂起裂的影响;还考虑了应力状态相关的破裂起裂。第三,推导了本构方程的有限元实现和坐标表达式。为了验证该模型的有效性,最后在动加载条件下对增材制造的材料级和裂纹扩展试件进行了试验。总体而言,所提出的相场模型能够较好地再现试验力-位移曲线和裂纹路径。单轴拉伸试验表明,较高的应变率会导致较高的硬化曲线和较低的塑性。其他材料样品进一步证明了预测应力状态和取向依赖的动态断裂的能力。为了准确地模拟动态裂纹路径,必须考虑各向异性起裂。最后,首次将相场模型应用于三周期最小表面(TPMS)结构的动态响应预测。有效捕获了动态裂纹模式,并对断裂机理进行了深入分析。该研究为动态韧性断裂提供了明确的相场框架,并应用于增材制造材料和结构。


A visco-hyperelastic constitutive model of hydrogel considering the coupling effect between segment motion and interchain slippage

Xinyu Liu, Qingsheng Yang, Xia Liu, Ran Tao, Wei Rao

doi:10.1016/j.jmps.2024.105996

考虑节段运动和链间滑移耦合效应的水凝胶粘-超弹性本构模型

Segment motion induces interchain slippage, leading to a complex coupling between hyperelastic and viscoelastic behaviors in hydrogels. Traditional models, which treat these behaviors separately and introduce a coupling free energy, struggle to capture this visco-hyperelastic coupling mechanism accurately. In this work, we develop a visco-hyperelastic constitutive model incorporating viscoelastic contributions into the general hyperelastic free energy to capture the coupling mechanism. The model introduces both the end-to-end distance and the envelope radius to describe the three-dimensional chain conformation. A joint probability distribution of these two parameters is used to capture the relationship between the chain conformation and the chain distribution. We also propose a two-level macro-micro transition framework to link the evolution of end-to-end distance and envelope radius to macroscopic deformations. In the first level of such macro-micro transition, the elongation of individual chains in various directions within the network is mapped to the overall chain elongation. In the second level, both interchain slippage and total chain elongation are incorporated into the overall deformation of the polymer network. A comparison between our predicted results with our experimental data demonstrates the predictability of the new model. Finally, the modeling results show that the interchain slippage always involves two sequential stages, i.e., orientation and relative slippage; and the increasing strain rate enhances the asynchronous responses between segment motion and relative slippage due to multichain interactions, making the viscoelastic responses of hydrogel more obvious.

片段运动引起链间滑移,导致水凝胶中超弹性和粘弹性行为之间的复杂耦合。传统模型分别处理这些行为并引入耦合自由能,难以准确地捕捉这种粘-超弹性耦合机制。在这项工作中,我们建立了一个粘-超弹性本构模型,将粘弹性贡献纳入一般超弹性自由能,以捕获耦合机制。该模型引入了端到端距离和包络半径来描述三维链的构象。这两个参数的联合概率分布用于捕获链构象和链分布之间的关系。我们还提出了一个两级宏观-微观过渡框架,将端到端距离和包络半径的演变与宏观变形联系起来。在这种宏观-微观过渡的第一级,网络内各个方向上单个链的延伸率被映射为整体链的延伸率。在第二级,链间滑移和总链伸长都被纳入聚合物网络的整体变形中。将我们的预测结果与实验数据进行比较,证明了新模型的可预测性。最后,仿真结果表明:链间滑移始终包含定向滑移和相对滑移两个连续阶段;随着应变速率的增大,由于多链相互作用,段运动与相对滑移之间的非同步响应增强,使得水凝胶的粘弹性响应更加明显。


Fracture process zone and fracture energy of heterogeneous soft materials

Xiang Wu, Xiao Li, Shuo Sun, Yilin Yu, Zhengjin Wang

doi:10.1016/j.jmps.2024.105997

非均质软材料断裂过程区与断裂能

Bio-inspired heterogeneous soft materials are under rapid development due to their superior fracture and fatigue resistance. In the last few years, several kinds of fibrous soft composites in different length scales have been fabricated. However, the fracture behavior and toughening mechanism of this class of materials are still elusive. Here we develop a theoretical model for the crack tip field of fiber reinforced soft composites. The distribution of deformation around the crack tip and released elastic energy during crack propagation are obtained. The fracture process zone and fracture energy are quantified. There is a critical sample height, below which the fracture process zone size and fracture energy are size-dependent, above which they approach material-specific constants: steady-state fracture process zone size and steady-state fracture energy. A formula is derived to relate the steady-state fracture process zone size and parameters of the composite. It is found that both the steady-state fracture process zone size and the critical sample height scale with the fractocohesive length of the composite. The steady-state fracture energy of the composite can be enhanced either by enlarging the fracture process zone size through tuning fiber geometry or by increasing the work to rupture of the fiber through chemical treatment. This work reveals the toughening mechanism of heterogeneous soft materials and paves the way to design soft materials of high fracture energy, high fatigue threshold, and low hysteresis. It also provides a practical guideline for determining the sample size to measure the steady-state fracture energy of heterogeneous soft materials.

仿生非均质软材料因其优异的抗断裂和抗疲劳性能而得到迅速发展。近年来,制备了几种不同长度尺度的纤维软复合材料。然而,这类材料的断裂行为和增韧机理尚不清楚。本文建立了纤维增强软质复合材料裂纹尖端场的理论模型。得到了裂纹扩展过程中裂纹尖端周围的变形分布和释放的弹性能。对断裂过程区和断裂能进行了量化。有一个临界样品高度,在此高度以下,断裂过程区尺寸和断裂能与尺寸相关,在此高度以上,它们接近于特定于材料的常数:稳态断裂过程区尺寸和稳态断裂能。导出了复合材料稳态断裂过程区尺寸与断裂参数的关系式。结果表明,复合材料的稳态断裂过程区尺寸和临界试样高度尺度均与断裂黏合长度有关。通过调整纤维几何形状,增大断裂过程区尺寸,或通过化学处理,增大纤维的断裂功,可以提高复合材料的稳态断裂能。本研究揭示了非均质软材料的增韧机理,为设计高断裂能、高疲劳阈值、低迟滞的软材料铺平了道路。为测量非均质软质材料稳态断裂能的试样尺寸确定提供了实用的指导。


Mechanics of Materials

An FFT based chemo-mechanical framework with fracture: Application to mesoscopic electrode degradation

Gabriel Zarzoso, Eduardo Roque, Francisco Montero-Chacón, Javier Segurado

doi:10.1016/j.mechmat.2024.105211

基于FFT的断裂化学力学框架:介观电极降解的应用

An FFT based method is proposed to simulate chemo-mechanical problems at the microscale including fracture, specially suited to predict crack formation during the intercalation process in batteries. The method involves three fields fully coupled, concentration, deformation gradient and damage. The mechanical problem is set in a finite strain framework and solved using Fourier Galerkin for non-linear problems in finite strains. The damage is modeled with Phase Field Fracture using a stress driving force. This problem is solved in Fourier space using conjugate gradient with an ad-hoc preconditioner. The chemical problem is modeled with the second Fick’s law and physically based chemical potentials, is integrated using backward Euler and is solved by Newton–Raphson combined with a conjugate gradient solver. Buffer layers are introduced to break the periodicity and emulate Neumann boundary conditions for incoming mass flux. The framework is validated against Finite Elements the results of both methods are very close in all the cases. Finally, the framework is used to simulate the fracture of active particles of graphite during ion intercalation. The method is able to solve large problems at a reduced computational cost and reproduces the shape of the cracks observed in real particles.

提出了一种基于FFT的微尺度化学力学问题(包括断裂)模拟方法,特别适用于电池嵌入过程中裂纹形成的预测。该方法涉及三个完全耦合的场:浓度场、变形梯度场和损伤场。将力学问题设置在有限应变框架中,并采用傅里叶伽辽金法求解有限应变非线性问题。损伤模型采用应力驱动相场断裂。在傅里叶空间中,利用共轭梯度和特别预条件解决了这一问题。化学问题用第二菲克定律和基于物理的化学势建模,用后向欧拉积分,用牛顿-拉夫森结合共轭梯度求解器求解。引入缓冲层来打破周期性并模拟入射质量通量的诺伊曼边界条件。对框架进行了有限元验证,两种方法的结果在所有情况下都非常接近。最后,利用该框架模拟了石墨活性粒子在离子插入过程中的断裂。该方法能够以较低的计算成本解决大问题,并能再现真实颗粒中观察到的裂纹形状。


Thin-Walled Structures

Effect of 0°-layers ratio on the dynamic fracture toughness of longitudinal compression failure of CFRP laminates

Zhuo Zhang, Kai Zhang, Gang Zhang, Bailin Zheng

doi:10.1016/j.tws.2024.112766

0°层数比对CFRP复合材料纵向压缩破坏动态断裂韧性的影响

The influence of layups on longitudinal compressive fracture toughness of CFRP laminates under quasi-static and high-rate loading conditions was studied in this paper. Three kind layups of laminates were compressed at speeds of 0.001 m/s, 5.7 m/s and 13.7 m/s with a universal test machine and electromagnetic Hopkinson bars. Surface displacement and strain of the specimen are recorded by digital image correlation systems and dynamic J integral was determined with the equivalent integral region method. The J-integral for longitudinal compression at crack initiation increases with an increasing proportion of the 0°-layer, attributed to enhanced interaction between fibers and the matrix. However, the fiber compressive fracture toughness exhibits negligible variation with loading rate when the proportion of the 0°-layer is small. In contrast, it decreases with increasing loading rate when the proportion is high.

研究了在准静态和高速率加载条件下,铺层对CFRP复合材料纵向压缩断裂韧性的影响。利用万能试验机和电磁霍普金森棒,分别以0.001 m/s、5.7 m/s和13.7 m/s的速度对三种层压板进行压缩。采用数字图像相关系统记录试样的表面位移和应变,采用等效积分区域法确定动态J积分。裂纹起裂时纵向压缩的j积分随着0°层比例的增加而增加,这是由于纤维与基体之间的相互作用增强。而当0°层掺量较小时,纤维的压缩断裂韧性随加载速率的变化可以忽略不计。当比例较大时,随着加载速率的增加,其减小。


Large amplitude vibration of rotating graphene reinforced titanium alloy dovetailed blades with general boundary conditions

Ming Yang Fan, Jie Chen

doi:10.1016/j.tws.2024.112801

石墨烯增强钛合金燕尾叶片在一般边界条件下的大振幅振动

Engine blades are generally installed on disks via dovetail joints, which can alleviate stress concentrations at the blade root and prevent heat transfer. As a result, the connection stiffness is strongly affected by the clearance between the blade and disk as well as the rotation speed of the blade. This paper first proposes a functionally graded graphene-reinforced titanium alloy trapezoid plate with elastic boundary conditions to investigate the large amplitude vibration of rotating dovetailed blades. The elastic boundaries are modelled by applying a series of artificial springs, and the related admissible displacement functions are constructed by orthogonal polynomials through the Gram–Schmidt process. The governing equations of the functionally graded graphene platelet reinforced composite (FG-GPLRC) trapezoid plate are derived by the first-order shear deformation theory (FSDT) and Lagrange equation. The numerical results of the large amplitude vibration of the plate are obtained by the weighted residual method combined with a direct iterative algorithm and verified through analytical solutions of the harmonic balance method. The effects of the stiffness of the constraint springs, rotation speed and structural parameters on the linear and nonlinear free vibrations of the FG-GPLRC trapezoid plate are thoroughly studied.

发动机叶片一般通过燕尾接头安装在圆盘上,这样可以缓解叶根处的应力集中,防止热传递。因此,连接刚度受到叶片与圆盘间隙以及叶片转速的强烈影响。本文首先提出了一种具有弹性边界条件的功能梯度石墨烯增强钛合金梯形板,用于研究旋转燕尾叶片的大振幅振动。采用一系列人工弹簧对弹性边界进行建模,并通过Gram-Schmidt过程用正交多项式构造相应的容许位移函数。利用一阶剪切变形理论(FSDT)和拉格朗日方程推导了功能梯度石墨烯血小板增强复合材料(FG-GPLRC)梯形板的控制方程。采用加权残差法与直接迭代法相结合的方法,得到了平板大振幅振动的数值计算结果,并通过谐波平衡法的解析解进行了验证。研究了约束弹簧刚度、转速和结构参数对FG-GPLRC梯形板线性和非线性自由振动的影响。


Analytical study on the flexural wave band gaps of arbitrary periodic stiffened plates by using beam-plate coupling theory

Xunyu Li, Yinggang Li, Yong Hu, Weilin Zhao, Junwei Bai, Xiaobin Li

doi:10.1016/j.tws.2024.112802

用梁-板耦合理论分析任意周期加筋板的弯曲带隙

In this paper, the flexural wave band gap characteristics of periodic stiffened plates are studied by using beam-plate coupling theory. A theoretical model of arbitrary periodic stiffened plate is established considering the coupling effect of Timoshenko beam and Kirchhoff plate. The flexural wave band structures of periodic stiffened plate are calculated by using plane wave expansion method and Bloch theorem. Numerical calculation and experimental tests were conducted to verify the proposed theoretical model. In addition, the parametric studies were performed to examine the effects of geometric parameters on both bandgap and vibration reduction characteristics of periodic stiffened plate. Results show that periodic stiffened plate can yield significant flexural wave band gaps and vibration isolation performance in a specific frequency range, which shows a good agreement with numerical simulation and experimental results. The geometrical parameters of stiffened plates have a significant influence on adjusting low-frequency flexural wave band gaps. These research findings offer a new technical approach for low frequency vibration and sound optimization of stiffened structures.

本文利用梁-板耦合理论研究了周期加筋板的弯曲带隙特性。考虑Timoshenko梁与Kirchhoff板的耦合效应,建立了任意周期加筋板的理论模型。采用平面波展开法和布洛赫定理计算了周期加筋板的弯曲带结构。通过数值计算和实验验证了所提出的理论模型。此外,还进行了参数化研究,考察几何参数对周期性加筋板带隙和减振特性的影响。结果表明:周期加筋板在特定频率范围内具有显著的弯曲带隙和隔振性能,与数值模拟和实验结果吻合较好;加筋板的几何参数对低频弯曲带隙的调节有显著影响。这些研究成果为加强结构的低频振动和声优化提供了新的技术途径。


Experimental and numerical investigations on the mechanical behavior of composite pre-tightened tooth connection under impact loading

Ming-Zhao Chen, Fei Li, Qi-Lin Zhao, Dong-Dong Zhang, Shu-Ting Ye, Wei-Bo Yang

doi:10.1016/j.tws.2024.112803

冲击载荷作用下复合材料预紧齿连接力学性能的实验与数值研究

The composite Pre-Tightened Tooth Connection (PTTC) is characterized by high connection efficiency and large bearing capacity, specifically designed for use in fiber-reinforced polymer (FRP)-metal protective structures that are inherently subjected to impact loads. In this study, impact tests were performed on single- and double-tooth specimens under high-velocity impact loads using the Split Hopkinson Pressure Bar (SHPB) apparatus to investigate their impact behavior. Additionally, a progressive damage model was numerically developed and validated against the experimental results to examine the failure patterns and mechanisms of the PTTC. The effects of tooth depth, tooth length, number of teeth, and impact velocity on the impact behavior were also analyzed parametrically. The results indicated that the primary failure modes of the PTTC are ductile compression-shear failure and brittle shear failure. In cases of compression-shear failure, the bearing capacity is lower than that of shear failure; however, it exhibits superior energy absorption characteristics. Therefore, it is recommended that the PTTC be designed to facilitate compression-shear failure when subjected to high-velocity impact. The length, depth, and number of teeth significantly influence the failure mode, bearing capacity, and energy absorption of the PTTC. Adequate design attention should be given to these factors for applications involving impact loads.

复合材料预紧齿连接(PTTC)具有连接效率高、承载能力大的特点,专门用于承受冲击载荷的纤维增强聚合物(FRP)-金属保护结构。在本研究中,使用分离式霍普金森压力杆(SHPB)装置对高速冲击载荷下的单齿和双齿试件进行了冲击试验,以研究它们的冲击行为。此外,还建立了一个渐进损伤模型,并与实验结果进行了验证,以检验PTTC的破坏模式和机制。参数化分析了齿深、齿长、齿数和冲击速度对冲击性能的影响。结果表明:PTTC的主要破坏模式为延性压剪破坏和脆性剪切破坏;压剪破坏时,承载力低于剪切破坏;然而,它表现出优越的能量吸收特性。因此,建议将PTTC设计为易于在高速冲击下发生压剪破坏。齿的长度、深度和数量对PTTC的失效模式、承载能力和能量吸收有显著影响。对于涉及冲击载荷的应用,在设计时应充分注意这些因素。


Achieving Broadband RCS Reduction on Curved Surfaces through Gradient Unit Design and Partition Layout Strategy

Mengzhou Chen, Liuying Wang, Gu Liu, Chaoqun Ge, Long Wang, Tonghao Liu, Dichen Li, Qingxuan Liang, Yixing Huang

doi:10.1016/j.tws.2024.112804

通过梯度单元设计和分区布局策略实现曲面宽带RCS缩减

Novel metastructure designs can efficiently manipulate electromagnetic responses. However, achieving exceptional electromagnetic manipulation capabilities in conformal states remains challenging. Herein, we proposed an innovative method that integrates gradient units with the partition layout strategy to facilitate broadband radar cross section (RCS) reduction under different curvatures. The proposed metastructure demonstrates broadband impedance matching characteristics through a gradient multi-layer design and exhibits strong adaptability to complex structures owing to the application of additive manufacturing technology. It demonstrates a remarkable -10 dB RCS reduction across a wide frequency bandwidth of 5.4–18 GHz in its planar state by integrating the micro-material composition and macro-geometry design while maintaining RCS reduction within the central angle range up to 90°. This paper presents a straightforward and innovative approach for constructing conformal metastructures, highlighting their potential applications in both military and civilian domains.

新的元结构设计可以有效地控制电磁响应。然而,在保形状态下实现特殊的电磁操纵能力仍然具有挑战性。为此,我们提出了一种将梯度单元与分区布局策略相结合的创新方法,以促进不同曲率下宽带雷达截面(RCS)的减小。该元结构通过梯度多层设计具有宽带阻抗匹配特性,并由于增材制造技术的应用而对复杂结构具有较强的适应性。通过集成微材料成分和宏观几何设计,在平面状态下,在5.4-18 GHz的宽频带上,RCS显著降低-10 dB,同时保持RCS降低在高达90°的中心角范围内。本文提出了一种简单而创新的构造保形元结构的方法,并强调了其在军事和民用领域的潜在应用。



来源:复合材料力学仿真Composites FEM
ACTMechanicalAdditiveSystemFlux振动显式动力学疲劳断裂复合材料非线性通用增材裂纹理论材料仿生创新方法
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【新文速递】2024年11月28日固体力学SCI期刊最新文章

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,International Journal of Plasticity 1 篇,Thin-Walled Structures 6 篇International Journal of Solids and StructuresAnalytical and experimental studies on the sequential flaring-buckling behavior of combined bi-tubes in blind boltsJiaming Feng, Yuyin Sun, Wanjun Jin, Ridong Liaodoi:10.1016/j.ijsolstr.2024.113158盲螺栓组合双管序贯扩曲行为的分析与实验研究Combined bi-tubes are innovatively applied in modern composite blind bolts to provide the clamping force. In this study, the sequential flaring-buckling behavior of combined bi-tubes under axial compression on expanding dies was experimentally and analytically investigated. First, axial compression tests were performed on bi-tubes in three different dimension groups. Based on the test results, deformation modes and force–displacement curves were obtained to assess the specific energy absorption (SEA), clamping energy (ECL), and energy transfer ratio (ETR). The results show that bi-tubes have superior energy-absorbing capacity and clamping efficiency. SEA can reach 21 kJ/kg, and the ECL accounts for 50 ± 6 % of the total energy dissipated. Afterwards, a theoretical solution for flaring-buckling bi-tubes, which involves the flaring forming force, friction, and critical buckling force, was derived on the basis of an equal-thickness circular tube. A comparison of forces and deformation modes from analytical and experimental approaches leads to the observations that the analytical theory can assess the sequential flaring-buckling bi-tubes within acceptable proximity, the maximum deviations of flaring forming forces and critical buckling forces being 3.3 % and 6.6 %, and that it can effectively predict diverse deformation modes, i.e., a single bell-shaped bulb on the clamped structure, an upper bulb close to the platen, or double bulbs. This study is expected to provide guidance for the optimal design of the clamping structure on aircraft and automobiles.复合双管在现代复合盲螺栓中创新性地用于提供夹紧力。在这项研究中,对在扩张模具上受轴向压缩的复合双管的渐进性失稳-屈曲行为进行了实验和理论研究。首先,对三种不同尺寸组的双管进行了轴向压缩试验。基于试验结果,获得了变形模式和力-位移曲线,以评估特定能量吸收(SEA)、夹紧能量(ECL)和能量传递比(ETR)。结果表明,双管具有优越的能量吸收能力和夹紧效率。SEA可达21千焦/千克,ECL占总能量耗散的50±6%。然后,基于等厚度圆管,推导了涉及鼓胀成形力、摩擦和临界屈曲力的渐进性失稳-屈曲双管的理论解。通过理论分析和实验方法对力和变形模式进行比较,可以得出以下观察结果:理论分析可以对可接受范围内的双管的渐进性鼓胀-失稳过程进行评估,鼓胀成形力的最大偏差为3.3%,失稳力的最大偏差为6.6%;它还可以有效地预测各种变形模式,如固定结构上的单个钟形凸起、靠近压板的上凸起或双凸起。这项研究有望为飞机和汽车的夹紧结构的优化设计提供指导。Journal of the Mechanics and Physics of SolidsFoldable piecewise linear origami that approximates curved tile origamiHuan Liu, Richard D. Jamesdoi:10.1016/j.jmps.2024.105962可折叠的分段线性折纸,近似于弯曲的瓷砖折纸Curved origami featuring curved tiles can store elastic energy and bias the structure toward a desired shape when subjected to appropriate constraints. Without constraints, however, a curved origami structure generally has infinitely many degrees of freedom. For engineering applications in which a particular folding motion is desired, a great many constraints have to be introduced. One natural strategy to reduce degrees of freedom is to discretize curved origami into piecewise linear origami while closely approximating the desired curved folding motion. Then, as we show, the degrees of freedom are vastly reduced (typically to one DoF in cases where the folding angle at the crease is not trivial, and excluding overall rigid body motions). In this paper we present a Lagrangian approach for constructing curved origami structures which is complementary to our approach in Liu and James (2024). Then, we generalize this approach to allow quite general curved creases. We outline a way to discretize curved crease patterns and present two optimization methods to refine these patterns. Our approach ensures that the deformed piecewise linear origami closely matches the folding angles and crease configurations of the curved origami. Piecewise linear origami structures that approximate curved origami offer promising potential for architectural and robotic design applications. They also give an efficient way to design desired smooth structures by optimizing finite-dimensional piecewise linear structures.具有弯曲瓷砖的弯曲折纸可以存储弹性能量,并在受到适当的约束时使结构偏向所需的形状。然而,在没有约束的情况下,弯曲的折纸结构通常具有无限多个自由度。对于需要特定折叠运动的工程应用,必须引入许多约束条件。降低自由度的一种自然策略是将曲线折纸离散化为分段线性折纸,同时又近似于期望的弯曲折叠运动。然后,正如我们所示,自由度大大降低(通常在折痕处的折叠角度不是微不足道的情况下为一个DoF,并且排除了整体刚体运动)。在本文中,我们提出了一种构造弯曲折纸结构的拉格朗日方法,该方法与我们在Liu和James(2024)中的方法相补充。然后,我们将这种方法推广到允许相当一般的弯曲折痕。我们概述了一种离散化曲线折痕图案的方法,并提出了两种优化方法来细化这些图案。我们的方法保证了变形的分段线性折纸与弯曲折纸的折叠角度和折痕构型紧密匹配。近似曲面折纸的分段线性折纸结构为建筑和机器人设计应用提供了很好的潜力。通过优化有限维分段线性结构,给出了一种设计理想光滑结构的有效方法。Mechanics of MaterialsPredicting the evolution of texture and grain size during deformation and recrystallization of polycrystals using field fluctuations viscoplastic self-consistent crystal plasticityIftekhar A. Riyad, Marko Knezevicdoi:10.1016/j.mechmat.2024.105212利用场波动粘塑性自洽晶体塑性预测多晶变形和再结晶过程中织构和晶粒尺寸的演变This paper advances a recent formulation of a field fluctuations viscoplastic self-consistent (FF-VPSC) crystal plasticity model to predict not only the evolution of texture in polycrystalline metals undergoing deformation and recrystallization but also the evolution of grain size. The model considers stress and lattice rotation rate fluctuations inside grains to calculate intragranular misorientation spreads. The spreads are used for modeling of grain fragmentation during deformation and grain nucleation during recrystallization enabling the predictions of concomitant evolution of texture and grain size distributions. The evolutions of textures and grain size distributions are first simulated for commercially pure Cu undergoing severe plastic deformation (SPD) in high pressure torsion to agree well with corresponding experimental data. Next, the evolution of texture and grain size in an aluminum alloy (AA) 5182-O after simple tension and static recrystallization are predicted and compared with experiments. Finally, the predictions of texture and grain size distributions in a magnesium alloy WE43 undergoing a thermo-mechanical loading in the dynamic recrystallization regime are presented and compared with experiments. After validation, the model is coupled with the implicit finite element method (FEM) via a user-material subroutine (UMAT) in Abaqus to facilitate modeling of complex boundary conditions and geometries. The multilevel approach is referred to as FE-FF-VPSC in which every integration point embeds the FF-VPSC constitutive law, considering texture evolution and the directionality of deformation mechanisms operating at the single crystal level. FE-FF-VPSC is applied to simulate a sequence of rolling, recrystallization, and deep drawing of a circular cup of AA6022-T4. The simulated processing sequence demonstrates the versatility of the simulation framework developed in the present paper in not only predicting texture and grain size evolution and phenomena pertaining to behavior of materials but also geometrical shape changes important for the optimization of metal forming processes. To this end, the effects of initial texture and underlying anisotropy on the formation of earing profiles during deep drawing are simulated and discussed.本文提出了一种新的场波动粘塑性自洽(FF-VPSC)晶体塑性模型,该模型不仅可以预测多晶金属在变形和再结晶过程中的织构演变,还可以预测晶粒尺寸的演变。该模型考虑了晶粒内部的应力和晶格旋转速率波动来计算晶粒内部的取向偏差扩展。扩展用于模拟变形过程中的晶粒碎裂和再结晶过程中的晶粒成核,从而预测织构和晶粒尺寸分布的伴随演变。首次模拟了商业纯铜在高压扭转下剧烈塑性变形(SPD)的织构演变和晶粒尺寸分布,与相应的实验数据吻合较好。其次,对铝合金(AA) 5182-O经过简单拉伸和静态再结晶后织构和晶粒尺寸的演变进行了预测,并与实验结果进行了比较。最后,对WE43镁合金在动态再结晶过程中的织构和晶粒尺寸分布进行了预测,并与实验结果进行了比较。验证后,通过Abaqus中的用户-材料子程序(UMAT)将模型与隐式有限元法(FEM)耦合,以方便复杂边界条件和几何形状的建模。多层方法被称为FE-FF-VPSC,其中每个积分点都嵌入了FF-VPSC本构律,考虑了织构演化和在单晶水平上运行的变形机制的方向性。采用FE-FF-VPSC模拟了AA6022-T4圆杯的轧制、再结晶和拉深过程。模拟的加工序列证明了本文开发的模拟框架的通用性,不仅可以预测材料的织构和晶粒尺寸演变以及与材料行为有关的现象,还可以预测金属成形工艺优化中重要的几何形状变化。为此,模拟并讨论了拉深过程中初始织构和下伏各向异性对耳纹轮廓形成的影响。International Journal of PlasticityThe Derivation of CRSS in pure Ti and Ti-Al AlloysDaegun You, Orcun Koray Celebi, Ahmed Sameer Khan Mohammed, Ashley Bucsek, Huseyin Sehitogludoi:10.1016/j.ijplas.2024.104187纯Ti和Ti- al合金中CRSS的衍生The work focuses on the determination of the critical resolved shear stress (CRSS) in titanium (Ti) and titanium-aluminum (Ti-Al) alloys, influenced by an array of factors such as non-symmetric fault energies and minimum energy paths, dislocation core-widths, short-range order (SRO) effects which alter the local atomic environment, and tension-compression (T-C) asymmetry affected by intermittent slip motion. To address these multifaceted complexities, an advanced theory has been developed, offering an in-depth understanding of the mechanisms underlying slip behavior. The active slip systems in these materials are basal, prismatic, and pyramidal planes, with the latter involving both 〈a〉and 〈c+a〉 dislocations. Each slip system is characterized by distinct Wigner-Seitz cell configurations for misfit energy calculations, varying partial dislocation separation distances, and unique dislocation trajectories—all critical to precise CRSS calculations. The theoretical CRSS results were validated against a comprehensive range of experimental data, demonstrating a strong agreement and underscoring the model's efficacy.该研究旨在确定钛(Ti)和钛铝(Ti-Al)合金的临界解理应力(CRSS),受到非对称断层能量和最小能量路径、位错芯宽度、改变局部原子环境的短程有序(SRO)效应以及由间歇滑移运动引起的拉伸压缩(T-C)不对称性的影响。为了解决这些复杂因素,开发了一种先进的理论,深入理解滑移行为背后的机制。这些材料中的活性滑移系统是基面、棱柱面和平面,后者涉及和<c+a>位错。每个滑移系统都有独特的威格纳-塞茨(Wigner-Seitz)胞结构,用于计算位错能,部分位错分离距离和独特的位错轨迹,这些都是精确计算CRSS的关键。理论计算的CRSS结果与广泛的实验数据相吻合,证明了模型的有效性。Thin-Walled StructuresInflation of a Toroidal Membrane within a Fluid-filled Elastic Spherical EnclosureSatyajit Sahu, Soham Roychowdhurydoi:10.1016/j.tws.2024.112729充液弹性球壳内环形膜的膨胀The present research investigates the growth based inflation model of an inflated toroidal membrane within a fluid-filled environment enclosed by an elastic spherical cavity. This problem statement resembles the growth of toroidal vesicle membranes within biological cells. The toroidal membrane is described by hyperelastic Mooney–Rivlin model with meridional anisotropy. The rise in internal gauge pressure of the torus causes the surrounding incompressible fluid to exert a distributed radial force on the surface of the elastic sphere, resulting in its deformation. With a subsequent gradual increase in gauge pressure, a contact is initiated as the torus indents onto the inner surface of the elastic sphere. The contact condition is assumed to be frictionless, and a variational formulation is adopted for solving the contact problem. The maximum indentation as well as the generated contact stress are found to be higher with a lesser stiffness of the elastic spherical enclosure. As the contact patch grows, the phenomenon of membrane thinning is predominantly observed at the inner equator of the torus. The growth of the contact boundary varies linearly with increasing torus gauge pressure, but non-linearly with the fluid pressure within the spherical enclosure.本文研究了弹性球腔包围的充液环境中膨胀环形膜的生长膨胀模型。这个问题陈述类似于生物细胞内环形囊泡膜的生长。环形膜采用具有子向各向异性的超弹性Mooney-Rivlin模型来描述。环面内部表压的升高,使周围不可压缩流体对弹性球表面施加分布径向力,造成弹性球变形。随着随后表压的逐渐增加,当环面缩进弹性球的内表面时,接触开始。假定接触条件为无摩擦,采用变分公式求解接触问题。最大压痕和产生的接触应力发现较高的刚度较小的弹性球面外壳。随着接触片的增大,在环面的内赤道处主要观察到薄膜变薄的现象。接触边界的增长随环面表压的增加呈线性变化,但与球壳内流体压力呈非线性变化。First-order GBT for tapered regular convex polygonal tubesRodrigo Gonçalvesdoi:10.1016/j.tws.2024.112735锥形正则凸多边形管的一阶GBTThis paper presents an accurate and efficient first-order Generalized Beam Theory (GBT) for linearly tapered regular convex polygonal tubes, such as those widely employed in the construction industry. Even though tapered members require a significantly involved formulation, it is shown that it is possible to enforce the standard GBT assumptions exactly, without additional simplifications, a key aspect that (i) is essential for the accuracy and computational performance of the formulation and (ii) allows identifying the deformed configurations pertaining to inextensible deformation. Consequently, very accurate solutions are achieved even for complex cases, such as tubes with a high taper angle and undergoing localized deformation. The GBT deformation modes for the prismatic case are directly used, meaning that the proposed approach for tapered tubes does not require a specific GBT cross-section analysis procedure. All expressions are presented in a straightforward vector-matrix format, for implementation purposes. The excellent performance of the resulting displacement-based beam finite element and the advantages of the GBT modal decomposition features are highlighted through several numerical examples, where results obtained with refined shell finite element models are used for comparison purposes.本文提出了一种精确有效的一阶广义梁理论(GBT),适用于建筑行业中广泛使用的线性锥形规则凸多边形管。尽管锥形构件需要一个非常复杂的公式,但研究表明,在没有额外简化的情况下,可以准确地执行标准GBT假设,这是一个关键方面,(i)对公式的准确性和计算性能至关重要,(ii)允许识别与不可扩展变形有关的变形配置。因此,即使对于复杂的情况,例如具有高锥度角和经历局部变形的管,也可以获得非常精确的解决方案。直接使用棱柱体情况下的GBT变形模式,这意味着锥形管的建议方法不需要特定的GBT截面分析程序。为了实现目的,所有表达式都以直接的向量矩阵格式呈现。通过几个数值算例,突出了基于位移的梁有限元的优异性能和GBT模态分解特征的优势,其中使用精细化壳有限元模型获得的结果用于比较目的。Study on the blast mitigation behavior of metakaolin-based foam geopolymer (MKFG) as tunnel cushioning layer against external blastsWenxin Wang, Fangduo Xiao, Hang Zhou, Shikun Chen, Zhen Wang, Yi Liu, Dongming Yandoi:10.1016/j.tws.2024.112752偏高岭土基泡沫地聚合物(MKFG)作为隧道外爆缓冲层的缓震性能研究In this study, the similarity model contact blast test and numerical simulations were carried out to investigate the protective behavior of tunnels with a metakaolin-based foam geopolymer (MKFG) cushioning layer under blast impacts. In contact blast test, Rock-Foam Geopolymer-Concrete Tunnel (RFGCT) structures with various densities (400, 600 and 800 kg/m3) of MKFG were tested against a blast impact of 100 g TNT. In numerical simulations, several parameters covering TNT equivalent as well as density and thickness of cushioning cladding, were comprehensively discussed. Test results show that the attenuation rate of cushioning cladding to the blast wave is enhanced from 34.7% to 71.0% with the reduction of the density of MKFG from 800 kg/m3 to 400 kg/m3. Meanwhile, the reflected tensile wave generated by blast wave falls from 1.85 MPa to 0.66 MPa. When the density of MKFG exceeds 600 kg/m3, the cladding exists obvious defects in energy absorption at the bottom of mid-span and free end, which gradually disappear as the TNT equivalent and cushioning thickness increases. Increasing thickness of the MKFG-400 can lead to excessive overall displacement of the tunnel lining. Full-size uncertainty analysis shows that at TNT equivalents of 2000 kg, the thickness of MKFG-800 as cushion is recommended to be 2-3 times that of the lining.采用相似模型接触爆破试验和数值模拟方法,研究了在爆炸冲击作用下,采用变高岭土泡沫地聚合物(MKFG)缓冲层对隧道的保护作用。在接触爆炸试验中,采用不同密度(400、600和800 kg/m3)的MKFG对岩石-泡沫地聚合物-混凝土隧道(RFGCT)结构进行了100 g TNT爆炸冲击试验。在数值模拟中,对TNT当量、缓冲包层密度和厚度等参数进行了全面讨论。试验结果表明,当MKFG密度从800 kg/m3降低到400 kg/m3时,缓冲包层对冲击波的衰减率从34.7%提高到71.0%;同时,冲击波产生的反射拉伸波从1.85 MPa下降到0.66 MPa。当MKFG密度超过600 kg/m3时,包层在跨中底部和自由端存在明显的吸能缺陷,随着TNT当量和缓冲厚度的增加,吸能缺陷逐渐消失。增加MKFG-400厚度会导致隧道衬砌整体 位移过大。全尺寸不确定度分析表明,在TNT当量为2000 kg时,MKFG-800作为垫层的厚度建议为衬里厚度的2-3倍。Residual compressive behaviour and CFRP strengthening of SRCFST columns after combined damage of fire and lateral impactSun-Hang Ji, Wen-Da Wang, Yan-Li Shi, Long Zhengdoi:10.1016/j.tws.2024.112756SRCFST柱在火灾和侧向冲击复合损伤后的残余压缩性能及CFRP加固Composite structure may be subjected to impact and fire during its service life, and the damaged member face challenges in the performance evaluation and strengthening. This study conducted an experimental and numerical investigation into the residual compressive behaviour of steel-reinforced concrete-filled steel tubular (SRCFST) columns after combined damage of fire and lateral impact. Thirteen damaged specimens under axial loading were tested, with three specimens strengthened with carbon fiber reinforced polymer (CFRP). The failure modes of specimens, residual compressive capacity, deflection distribution, and strain development were discussed. The finite element analysis model on the residual compressive behaviour of damaged SRCFST columns was then developed and calibrated. The full-range analysis on the residual performance of damaged columns was carried out, included the temperature development, distribution of axial load and bending moment, degradation mechanism of bearing capacity, stress development, and effects of fire exposure time. The parameter study was finally conducted to investigate the effects of various factors on the residual compressive performance of damaged SRCFST columns. The results indicated that increasing the fire exposure time and impact height reduces visibly the residual compressive capacity of fire-damaged specimens. As the two damages accumulate, the axial load of each component gradually reduces, while the axial compressive capacity proportion redistributes.复合材料结构在使用寿命期间可能会受到冲击和火灾的影响,受损构件在性能评估和加固方面面临挑战。本文对钢管混凝土柱在火灾和侧向冲击双重作用下的残余压缩性能进行了试验和数值研究。对13个轴向损伤试件进行了试验,其中3个试件采用碳纤维增强聚合物(CFRP)加固。讨论了试件的破坏模式、残余抗压能力、挠度分布和应变发展情况。建立了钢筋混凝土混凝土损伤柱残余压缩特性有限元分析模型并进行了标定。对受损柱的残余性能进行了全面分析,包括温度发展、轴向荷载和弯矩分布、承载力退化机制、应力发展以及火灾暴露时间的影响。最后进行了参数研究,探讨了各种因素对损伤混凝土混凝土柱残余抗压性能的影响。结果表明,增加火灾暴露时间和冲击高度可明显降低火灾损伤试件的残余抗压能力。随着两种损伤的累积,各构件轴向载荷逐渐减小,轴向抗压能力比例重新分配。General analytical solution for stress intensity factors of two asymmetrical radial cracks emanating from a single hole in an infinite isotropic plateShengfan Bi, Yong Huang, Hao Wangdoi:10.1016/j.tws.2024.112759无限大各向同性板中单孔产生的两个不对称径向裂纹应力强度因子的一般解析解Thin-walled perforated structures are widely used in modern industry, where cracks may emanate from the hole edges due to structural loads and manufacturing processes, potentially reducing the reliability of the structure. This paper presents a general solution for stress intensity factors (SIFs) of two asymmetrical radial cracks emanating from a single hole in an infinite isotropic plate, utilizing complex variable theory. Hole shapes, including quasi-square, parabolic, and pentagonal, etc., are considered as instances, and SIFs at crack tips and stress distributions around the hole edge are provided. The analytical solutions are compared with existing literature and finite element method (FEM) results, which confirm the reliability. Under uniaxial tension or pure shear, for quasi-square, parabolic, and pentagonal shapes with equal crack lengths (a/H=0.5), the maximum stress occurs near the geometric vertices. As the crack length increases, the influence of the hole shape diminishes, causing SIF values to approach those of a Griffith crack.薄壁穿孔结构在现代工业中得到了广泛应用,但由于结构载荷和制造工艺的原因,孔边缘可能会产生裂纹,从而降低结构的可靠性。本文利用复变函数理论提出了一种通用的解法,用于计算两个不对称的径向裂纹从单个孔中萌生出的无限各向同性板的应力强度因子(SIFs)。考虑了包括准方形、抛物线形和五边形等孔形状作为实例,并提供了裂纹尖端和孔边缘的应力分布。将解析解与现有文献和有限元法(FEM)结果进行了比较,证实了其可靠性。在单轴拉伸或纯剪切作用下,对于具有相等裂纹长度(a/H=0.5)的准方形、抛物线形和五边形孔形状,最大应力出现在几何顶点附近。随着裂纹长度的增加,孔形的影响逐渐减弱,导致SIF值接近Griffith裂纹的值。Diffusion bonding of TC4/TB8 titanium alloys with an interlayer by regulating temperature: Microstructure and mechanical performanceTianle Li, Renhao Wu, Man Jae SaGong, Zaigham Saeed Toor, Hyoung Seop Kimdoi:10.1016/j.tws.2024.112760 调节温度对TC4/TB8钛合金间层扩散连接的影响:组织与力学性能Diffusion bonding of α+β type TC4 (Ti-6Al-4V) and metastable β type TB8 (Ti-15Mo-2.7Nb-3Al-0.2Si) alloys with interlayer addition was systematically investigated by regulating temperature, revealing the discrepancies in interfacial microstructure and mechanical performance of the joints. Microstructural evolution at the TC4/Ti interfaces and TB8/Ti interfaces can be attributed to atomic interdiffusion and α/β transformation depending on temperature. Additionally, 7 of the 12 α variants that comply with the Burgers orientation relationship with β parents at the transitional layer are identified. The elongation of the bonded samples upon the tensile direction perpendicular to the interfaces becomes decreased compared to that of samples subjected to the tensile direction parallel to the interfaces. The dislocation characteristics and fracture models are analyzed after plastic deformation. This study indicates that a two-step method (first high-temperature and short-duration, then low-temperature and long-duration) can optimize the microstructure and mechanical performance of joints for Ti alloys exposed to high temperatures.通过调节温度,系统研究了层间添加α+β型TC4 (Ti-6Al-4V)和亚稳型TB8 (Ti-15Mo-2.7Nb-3Al-0.2Si)合金的扩散结合,揭示了界面组织和接头力学性能的差异。TC4/Ti界面和TB8/Ti界面的微观组织演变可归因于原子间扩散和随温度的α/β转变。此外,12个α变体中有7个在过渡层与β亲本符合Burgers取向关系。与平行于界面的拉伸方向相比,在垂直于界面的拉伸方向上,粘结试样的伸长率降低。分析了塑性变形后的位错特征和断裂模式。本研究表明,采用高温短持续时间、低温长持续时间两步法可以优化钛合金高温接头的组织和力学性能。来源:复合材料力学仿真Composites FEM

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