【新文速递】2023年12月14日固体力学SCI期刊最新文章

今日更新：Journal of the Mechanics and Physics of Solids 1 篇，Mechanics of Materials 1 篇，International Journal of Plasticity 1 篇，Thin-Walled Structures 4 篇

Journal of the Mechanics and Physics of Solids

Achieving irreversibility in damage evolution: Extended gradient damage model with decoupled damage profile and cohesive law

Liang Xue, Xiaodan Ren

doi:10.1016/j.jmps.2023.105524

实现损伤演化的不可逆性:具有解耦损伤轮廓和内聚律的扩展梯度损伤模型

The irreversibility of damage evolution is a cornerstone of classical damage mechanics. Unfortunately, the existing gradient damage models in the literature cannot always fulfill this critical condition. Therefore, the Extended Gradient Damage (EGD) model is proposed in the present work in response to this challenge. In the EGD model, the governing equation of damage evolution is developed in the form that the damage evolution and cohesive law are fully decoupled. Thus, the irreversible damage evolution could be easily established by defining a well-behaved damage profile function without any intervention from cohesive law. Other than that, complex cohesive laws for different materials could be well captured in the EGD model with the help of the integral transformation technique. Moreover, the variational form of the proposed EGD model is developed by taking advantage of the dissipative force term, and the principle of thermodynamics is proven to be fulfilled. In the end, the proposed EGD model is validated by four numerical examples.

损伤演化的不可逆性是经典损伤力学的基础。遗憾的是，现有文献中的梯度损伤模型并不总是满足这一临界条件。为此，本文提出了扩展梯度损伤(EGD)模型。在EGD模型中，损伤演化控制方程采用损伤演化与内聚律完全解耦的形式。因此，在不受内聚律干扰的情况下，通过定义一个行为良好的损伤剖面函数，可以很容易地建立不可逆损伤演化。除此之外，在积分变换技术的帮助下，EGD模型可以很好地捕获不同材料的复杂内聚规律。此外，利用耗散力项建立了EGD模型的变分形式，证明了该模型符合热力学原理。最后，通过4个数值算例验证了所提出的EGD模型。

Mechanics of Materials

A unified viscoelastic constitutive model for studying the mechanical behaviors of polyelectrolyte complex hydrogels with different crosslinker degrees

Weicheng Cai, Zhenhua Xiao, Taolin Sun, Jiong Wang

doi:10.1016/j.mechmat.2023.104896

研究不同交联度聚电解质复合水凝胶力学行为的统一粘弹性本构模型

Bio-based hydrogels formed by the chemically or physically cross-links are promising materials in the biological system. In this paper, we propose a constitutive model within the framework of finite-strain viscoelasticity to investigate the mechanical behaviors of bio-based polyelectrolyte complex (PEC) hydrogels from the ionic complexation of sodium hyaluronate (HA)/chitosan with and without chemical crosslinkers. The structure of the viscoelastic constitutive model consists of a spring and a Kelvin element, in which two softening factors are adopted to represent the states of ionic bonds and bridges in the hydrogels. Based on some constitutive assumptions and through the conventional approach of thermodynamics, the constitutive equation system of the model is derived. Corresponding to the hydrogels with different crosslinker concentrations, the values of material parameters in the model are identified. To show the validity of the model, it is applied to simulate the mechanical behaviors of the hydrogel samples in the uniaxial tensile tests and cyclic loading-unloading tests. It is found that the model predictions can fit the experimental data quite well. Based on the modeling results, some further analyses regarding the effects of softening factors on the response of HA/chitosan hydrogels have also been conducted.

通过化学或物理交联形成的生物基水凝胶是生物系统中很有前途的材料。本文提出了一个有限应变粘弹性框架下的本构模型，研究了透明质酸钠(HA)/壳聚糖(壳聚糖)在有和没有化学交联剂的情况下离子络合生物基聚电解质复合物(PEC)水凝胶的力学行为。粘弹性本构模型的结构由弹簧和开尔文单元组成，其中采用两个软化因子表示水凝胶中离子键和桥的状态。在一些本构假设的基础上，通过传统的热力学方法，导出了该模型的本构方程组。根据不同交联剂浓度的水凝胶，确定了模型中材料参数的取值。为验证该模型的有效性，应用该模型模拟了水凝胶试样在单轴拉伸试验和循环加卸载试验中的力学行为。结果表明，模型预测结果与实验数据拟合较好。在此基础上，进一步分析了软化因素对HA/壳聚糖水凝胶反应的影响。

International Journal of Plasticity

A general scheme for point defect sink strength calculation and related machine-learning-based expressions

Kaizheng Yang, Yichao Zhu

doi:10.1016/j.ijplas.2023.103855

点缺陷汇强度计算的一般方案及相关的基于机器学习的表达式

Irradiation tends to increase the concentration of point defects (PDs) in crystalline materials, whose consecutive interactions with other types of defects, such as dislocation and void, are recognised highly responsible for the characteristic plastic and damaging behaviours of materials under irradiation. Conventional treatments on evaluating the strength of PD sinks see their limitation with strong regularity requirements over the models used for summarising the key underlying microstructural behaviours, where analytical solutions are bound to be the outcome. The present article serves to introduce a general scheme for PD sink strength evaluation, where constraints on solution analyticity are fully resolved with the use of machine learning. In particular, a neural network representation of the PD sink strength due to void/bubble is derived, where PD transportation tendencies against the hydrostatic pressure gradient surrounding a bubble can be considered in details. The treatment is also applied to analyse PD sink strength due to edge dislocation clusters. For nearly uniformly distributed clusters, upon undertaking a two-scale asymptotic strategy, the corresponding sink strength formulation becomes explicit. For randomly distributed dislocations, the sink strength is found to roughly scale with the onsite dislocation density. But for patterned dislocations, such as dislocation dipoles, their sink strength is suggested to vary with the applied load. The machine-learning-based formulation is also compared well with the results obtained by other multiscale methods.

辐照往往会增加晶体材料中的点缺陷(PDs)的浓度，这些点缺陷与其他类型的缺陷(如位错和空洞)的连续相互作用，被认为是辐照下材料特征塑性和破坏行为的高度原因。评估PD汇强度的常规处理方法看到了它们的局限性，对用于总结关键潜在微观结构行为的模型有很强的规则性要求，其中分析解必然是结果。本文介绍了一种用于PD sink强度评估的一般方案，其中对解分析性的约束通过使用机器学习完全解决。特别地，我们推导了由于空洞/气泡引起的PD吸收强度的神经网络表示，其中PD的运输倾向与气泡周围的静水压力梯度可以详细考虑。该处理还应用于分析由于边缘位错簇引起的PD sink强度。对于几乎均匀分布的集群，在采用双尺度渐近策略后，相应的汇强度公式变得明确。对于随机分布的位错，发现汇强度与现场位错密度大致成比例。但对于像位错偶极子这样的模式位错，其沉降强度则随外加载荷的变化而变化。将基于机器学习的公式与其他多尺度方法得到的结果进行了比较。

Thin-Walled Structures

Investigating Seismic Behaviour of Cold-Formed Steel Moment Frames with the Welded Through-Plate Flexural Connection

Mohammad Niksefat, Iman Shamim

doi:10.1016/j.tws.2023.111477

冷弯型钢跨板连接弯矩框架的抗震性能研究

The Cold-Formed Steel (CFS) construction in seismic regions requires carefully selecting and designing an approved seismic-force resisting system. Among the available seismically-resistant structural systems, the bolted CFS moment frames have recently gained some attention. However, given the currently existing design issues associated with the bolted connections in CFS moment frames, this paper seeks to conduct a numerical investigation into the potential substitution of bolt fasteners with the weld materials in CFS frames. The objective is to explore the possibility of including the welded connection as an alternative to bolted connections in subsequent editions of the ASCE 7 code. To this end, finite element models, consisting of two built-up CFS beams and twenty-three flare-bevel-groove and fillet weld specimens, are initially validated against the cyclically and monotonically loaded tests with data available in the relevant literature. Subsequently, the verified weld and CFS beam models are incorporated in the simulation of thirty-four CFS beam-to-column welded moment connections, each differing in beam dimension, weld length and size, and gusset plate thickness. The built-up beams comprise back-to-back and lip-to-lip double C-section profiles. Stress variations along the weld lines, derived initially from nonlinear finite element analyses and then computed from the theoretical elastic analysis, are compared to establish a basis for categorizing stress distribution patterns in the longitudinal welds. Finally, six CFS frames assembled with the welded moment connection and subjected to a combined column axial compression and cyclic lateral drift are examined, resulting in an estimated seismic modification coefficient, R, equal to 3.8. Overall, the welded moment connections demonstrate a stable seismic response with an average ductility ratio, μ, of 2.7. The dominant failure mode is a locally developed ductile fracture in the two end segments of the longitudinal welds, identified as critical regions.

在地震区进行冷弯型钢结构，需要认真选择和设计合格的抗震体系。在现有的抗震结构体系中，锚固CFS弯矩框架近年来受到了广泛的关注。然而，考虑到目前存在的与CFS框架螺栓连接相关的设计问题，本文试图对CFS框架中焊接材料替代螺栓紧固件的可能性进行数值研究。目的是探讨在ASCE 7规范的后续版本中，将焊接连接作为螺栓连接的替代方法的可能性。为此，有限元模型，包括两个组合式CFS梁和23个喇叭口坡口和角焊缝试件，初步验证了循环和单调加载试验与相关文献中的数据。随后，将验证的焊缝和CFS梁模型纳入34个CFS梁柱焊接力矩连接的模拟中，每个CFS梁柱焊接力矩连接的梁尺寸、焊缝长度和尺寸以及扣板厚度不同。组合梁包括背靠背和唇对唇双c剖面图。首先由非线性有限元分析得到沿焊缝的应力变化，然后由理论弹性分析计算得到应力变化，并将其进行比较，为纵向焊缝应力分布模式的分类奠定基础。最后，对6个采用焊接弯矩连接的CFS框架进行了测试，并对其进行了柱轴压和循环侧向漂移的组合，得到了估计的地震修正系数R，等于3.8。总体而言，焊接弯矩连接具有稳定的地震响应，其平均延性比μ为2.7。主要的破坏模式是纵向焊缝两端段局部发育的韧性断裂，被确定为临界区域。

The mechanical behaviour of a slip joint for an offshore wind turbine: First monitoring and modelling results

Maroš Mojto, Alessandro Cabboi

doi:10.1016/j.tws.2023.111482

海上风力涡轮机滑动接头的力学行为:首次监测和建模结果

This study aims at shedding light on the mechanical behaviour of a prototype monopile - wind turbine tower connection, constituted by a slip joint. Selected examples of data set recorded during a long term monitoring campaign are illustrated and discussed. The data set encompass axial and hoop stresses measured over the slip joint area, relative displacements of the slip joint with respect to the monopile and acceleration levels recorded above the slip joint. In parallel, an ideal and simplified Finite Element model (FEM) of the slip joint is developed, in order to interpret the observed experimental data. Experiments first highlight the relevance of modelling the manufacturing imperfections of the overlapping steel sections. Subsequently, both experiments and FEM show that states of prestress need to be accounted for. Such prestress states first originate from the installation process, and subsequently from further loading events, triggering settlements of the slip joint. Finally, experiments and FEM showcase the force transfer mechanisms from the upper part to the lower part of slip joint.

本研究的目的是阐明由滑移节构成的单桩-风力发电机组塔架连接的力学行为。在长期监测活动中记录的数据集的选定例子进行了说明和讨论。数据集包括在滑移节区域测量的轴向和环向应力，滑移节相对于单桩的相对位移以及滑移节上方记录的加速度水平。同时，建立了滑移节的理想简化有限元模型，以解释观测到的实验数据。实验首先强调了模拟重叠钢截面的制造缺陷的相关性。随后，试验和有限元分析均表明，预应力状态需要考虑在内。这种预应力状态首先来自于安装过程，随后来自于进一步的加载事件，触发了伸缩节的沉降。最后，通过试验和有限元分析，揭示了滑移节理由上部到下部的力传递机理。

Analysis of contact creep behaviour of nanofilled composites

Jie Zhu, Yunian Shen

doi:10.1016/j.tws.2023.111483

纳米填充复合材料的接触蠕变行为分析

An effective modelling method for analysing the contact creep behaviour of composite materials with different nanofillers was proposed. Considering both the contact and creep material nonlinearities, an augmented Lagrangian algorithm was used to treat the unilateral contact constraints, and a time-hardening creep constitutive equation was adopted to describe the deformation characteristics of the nanocomposites. The constitutive parameters were extracted through a series of linear fittings based on the multiaxial creep theory and creep test curves, and the accuracy of the constitutive equation was validated. The applications of the proposed modelling method were demonstrated using a rope-wheel contact system (RWCS), in which the wheels were made of polystyrene (PS) with carbon black (CB), multi-walled carbon nanotubes (MWCNT), or chemically reduced graphene oxide (CRGO). The results indicated that the addition of nanofillers significantly reduced the creep deformation of the contact zone. The CRGO exhibited a better anti-creep performance than that of CB and MWCNT. Compared with pure PS, the maximum deformation on the contact path of the nanocomposite wheel with 5.0 wt% CRGO sheets at 1500 s and 104 s was reduced by approximately 22% and 52%, respectively. The coefficient of friction μ had a strong influence on the contact creep deformation when μ < 0.3. Additionally, the anti-creep capability of the added nanofillers became more evident as the loading time increased. The contact creep deformation of the CRGO composite was less than one-tenth that of the matrix material after 30 d.

提出了一种分析不同纳米填料的复合材料接触蠕变行为的有效建模方法。考虑材料的接触非线性和蠕变非线性，采用增广拉格朗日算法处理单侧接触约束，采用时间硬化蠕变本构方程描述纳米复合材料的变形特性。基于多轴蠕变理论和蠕变试验曲线，通过一系列线性装配提取本构参数，验证了本构方程的准确性。采用绳轮接触系统(RWCS)演示了所提出的建模方法的应用，其中车轮由聚苯乙烯(PS)与炭黑(CB)，多壁碳纳米管(MWCNT)或化学还原氧化石墨烯(CRGO)制成。结果表明，纳米填料的加入显著降低了接触区的蠕变变形。CRGO的抗蠕变性能优于炭黑碳纳米管和MWCNT。与纯PS相比，添加5.0 wt% CRGO的纳米复合材料车轮在1500 s和104 s时接触路径上的最大变形分别减少了约22%和52%。当摩擦系数μ < 0.3时，摩擦系数μ对接触蠕变影响较大。此外，添加的纳米填料的抗蠕变能力随着加载时间的增加而变得更加明显。30d后，CRGO复合材料的接触蠕变小于基体材料的十分之一。

Feasibility of suppressing debonding failure for CFRP-hollow section steel tube composite member with a thick-walled section under tensile loading

Kun Zu, Bin Luo, Xing Ma, Er-gang Xiong

doi:10.1016/j.tws.2023.111484

抑制cfrp -厚壁空心截面钢管复合构件抗拉破坏的可行性

Carbon fiber reinforced polymer (CFRP) is extensively utilized to strengthen steel structures. However, the premature debonding failure of CFRP inhibits its validity in strengthening tensile steel structures. Accordingly, the introduction of a thick-walled hollow section steel tube located at both ends of the CFRP-hollow section steel tube (CFRP-HSST) composite member was developed for the strengthening of tensile members. The steel tube in the novel composite member is constituted of a middle thin-walled section and a pair of thick-walled sections at each end providing anti-debonding resistance. The strengthening efficiency of the novel composite member under axial tensile loading was experimentally investigated by 8 specimens, comprising 4 circular cross section and 4 square cross section composite members. It was found that the presence of thickened section could achieve the stress gradient of CFRP and distribute the adhesive's interfacial shear stress. In addition, the finite element model (FEM) of the proposed CFRP-HSST composite member was developed and examined the adhesive damage distribution and evolution, and subsequently, a parametric analysis was carried out. The results indicate that the novel CFRP-HSST composite member can be regarded as an efficient strengthening solution for suppressing the premature debonding failure as well as increasing the strengthening efficiency and strength utilization of CFRP.

碳纤维增强聚合物(CFRP)被广泛应用于钢结构加固。然而，碳纤维布的过早脱粘破坏抑制了其加固受拉钢结构的有效性。据此，在cfrp -空心截面钢管(CFRP-HSST)复合构件的两端引入厚壁空心截面钢管来加强受拉构件。新型复合构件中的钢管由中间薄壁截面和两端具有抗脱粘阻力的一对厚壁截面组成。通过8个试件，包括4个圆形截面和4个方形截面的复合材料构件，对新型复合材料构件在轴向拉伸载荷下的强化效果进行了试验研究。研究发现，增厚截面的存在可以实现CFRP的应力梯度，分布胶粘剂的界面剪应力。建立了CFRP-HSST复合材料构件的有限元模型，分析了构件的粘接损伤分布和演化规律，并进行了参数化分析。结果表明，新型CFRP- hsst复合构件可作为抑制CFRP过早脱粘破坏的有效加固方案，提高CFRP的加固效率和强度利用率。