今日更新:International Journal of Solids and Structures 1 篇,Mechanics of Materials 1 篇,Thin-Walled Structures 2 篇
Multiscale modeling and simulation on mechanical behavior of fiber reinforced concrete
Li Xiang-Nan, Zuo Xiao-Bao, Li Liang, Liu Jing-Han
doi:10.1016/j.ijsolstr.2023.112569
纤维增强混凝土力学行为的多尺度建模与模拟
A multiscale mechanical model is proposed to quantitatively describe the macro-mechanical behavior of fiber reinforced concrete (FRC) based on its multiscale material compositions. Firstly, according to the actual scale characteristics of compositions, the model of composite material at each scale of FRC, including hardened cement paste, cement mortar and meso-FRC, was geometrically reconstructed; Secondly, the equations of stiffness and strength of composite material at each scale were established by using the equivalent inclusion theory and Ottosen failure criterion, and a multiscale mechanical model of FRC was proposed by upscaling from stiffness and strength of microstructure to macro-mechanical behavior of FRC; Finally, after verified by the experimental results in the literature, the proposed model was used to numerically investigate the loading-induced stress response and the evolution of macro-mechanical properties of FRC in its curing process, as well as the influence of steel fiber parameters, such as volume fraction, aspect ratio and spatial orientation, on the mechanical properties of FRC.
根据纤维增强混凝土(FRC)的多尺度材料组成,提出了定量描述其宏观力学行为的多尺度力学模型。首先,根据成分的实际尺度特征,对 FRC 各尺度的复合材料模型(包括硬化水泥浆、水泥砂浆和介质 FRC)进行几何重构;其次,利用等效包容理论和 Ottosen 失效准则,建立各尺度复合材料的刚度和强度方程,并从微观结构的刚度和强度上升到 FRC 的宏观力学行为,提出了 FRC 的多尺度力学模型;最后,经 文献中的实验结果验证,利用所提出的模型对 FRC 固化过程中的加载诱导应力响应和宏观力学性能的演变,以及体积分数、长径比和空间取向等钢纤维参数对 FRC 力学性能的影响进行了数值研究。
Phase-field study of the solutes-interstitial loops interaction in Fe–Cr alloys
Wang Heran, Yu Kang, Wang Jincheng, Wu Lu, Zhang Wen, Zhang Jing
doi:10.1016/j.mechmat.2023.104865
铁铬合金中溶质-间隙环相互作用的相场研究
Interstitial dislocation loops are typically formed in post-irradiated materials, such as Ferritic-Martensitic Fe–Cr alloys. These loops demonstrate solute segregation along their perimeters, effectively pinning the dislocation climb and resulting in high-density, small-sized loops that cause embrittlement. Phase-field simulations were conducted to investigate the behavior of Cr segregation in the stress field of a<100> type and various a/2<111> type interstitial dislocation loops in post-irradiated Fe–10Cr alloy. The study considers the long-range elastic interaction of solute Cr within the stress field of dislocation loops in a cubic elastic anisotropic material. The findings reveal a nonuniform stress distribution along the loop's perimeter depending on the included angle of habit plane normal n and Burgers vector b; the nonuniformity becomes more pronounced as the Burgers vector deviates from the normal direction. Furthermore, this nonuniform stress induces Cr segregation within regions experiencing tensile stress and Cr depletion in compression stress regions. Furthermore, a comprehensive analytical solution has been developed to characterize the diverse stress fields and solute segregation induced by interstitial dislocation loops with varying habit planes and Burgers vectors. The proposed analytical model effectively depicts the stress distribution of various dislocation loops, resulting in a Cr segregation profile that closely approximates those obtained through phase-field simulations. A thorough analysis of solute segregation mechanisms also elucidates the dispersed fine-scale nature and high density observed in experimental investigations of dislocation loops.
铁素体-马氏体铁铬合金等辐照后材料中通常会形成间隙位错环。这些环路沿其周边显示出溶质偏析,有效地固定了位错的攀升,从而形成高密度、小尺寸的环路,导致脆化。我们进行了相场模拟,以研究辐照后 Fe-10Cr 合金中 a<100> 型和各种 a/2<111> 型间隙位错环应力场中的铬偏析行为。该研究考虑了在立方弹性各向异性材料中,溶质铬在差排环应力场中的长程弹性相互作用。研究结果表明,沿着差排环周边的应力分布不均匀,这取决于习性平面法线与布尔格斯矢量 b 的夹角;当布尔格斯矢量偏离法线方向时,这种不均匀性变得更加明显。此外,这种不均匀应力会在承受拉伸应力的区域诱发铬偏析,在压缩应力区域诱发铬损耗。此外,我们还开发了一种全面的分析解决方案,用于描述由具有不同习性平面和布尔矢量的间隙位错环引起的不同应力场和溶质偏析。所提出的分析模型有效地描述了各种位错环的应力分布,从而得出了与相场模拟所得结果非常接近的克拉偏析曲线。对溶质偏析机制的透彻分析还阐明了在差排环实验研究中观察到的分散细尺度性质和高密度。
Vibration analysis of FGM anisogrid lattice plates with one width fold based on the continuous model using the GDQE method
Luo Jijun, Peng Shengguang, Hou Suxia, Kiani Yaser
doi:10.1016/j.tws.2023.111386
使用 GDQE 方法对基于连续模型的单宽折叠 FGM anisogrid 格构板进行振动分析
This research tests the idea of folding on the free vibration response of anisogrid lattice plates. It is assumed that the oblique and straight ribs with functionally graded materials (FGMs) construct the lattice plate. The stiffness and mass of the whole plate are computed by employing the global continuous model based on the shear deformable orthotropic plates. Then a width fold is created in the plate to check its effect on improving the system's natural frequencies. An element-based 2D generalized differential quadrature method recently developed solves this problem. This method divides the physical domain into simple domains (patching) and distributes a series of nodes on each patch (quadrature scheme). The motion equations of each patch are derived using Hamilton's principle. Next, the displacement and stress resultant continuity conditions are satisfied between common nodes. After that, the obtained global equations are solved, and the natural frequencies of such structures are calculated. After validating the response with the available literature, the influence of composite characteristics and geometry on the folded FGM lattice plate is distinguished.
本研究测试了折叠对等栅格板自由振动响应的影响。假定斜肋和直肋由功能分级材料(FGM)构成格构板。通过采用基于剪切变形正交板的全局连续模型,计算整个板的刚度和质量。然后在板上创建宽度折叠,以检查其对改善系统固有频率的影响。最近开发的一种基于元素的二维广义微分正交方法解决了这一问题。该方法将物理域划分为多个简单域(补丁),并在每个补丁上分布一系列节点(正交方案)。利用汉密尔顿原理推导出每个补丁的运动方程。然后,在公共节点之间满足位移和应力结果连续性条件。之后,求解得到的全局方程,并计算出这种结构的固有频率。在根据现有文献对响应进行验证后,区分了复合材料特性和几何形状对折叠式 FGM 晶格板的影响。
Behaviour and design of high strength steel circular hollow section member under pure torsion
Devi Soibam Monika, Devi Sanasam Vipej, Singh Tekcham Gishan
doi:10.1016/j.tws.2023.111387
高强度钢圆形空心截面构件在纯扭力作用下的行为和设计
The paper presents a detailed numerical investigation on the performance of high strength steel (HSS) circular hollow section (CHS) member subjected to pure torsion. Three grades of HSS, viz., S700, S900 and S1100, were considered in the study. Finite element (FE) models were initially developed and validated against the available test results. Further, the validated FE models were used for parametric study. Cross-sections of varying thickness and diameters, as well as HSS grades, were considered for the parametric study. The results generated from the parametric study were then utilised to assess the effect of steel grades on the torsional capacities and deformed shapes at ultimate and post-ultimate capacities. The effect of ratio of yield strength to ultimate ratio on the normalised member capacities has also been studied. Furthermore, the applicability of existing design equations for members subjected to pure torsion have been assessed against the FE generated member capacities. Based on the analysis, most of design predictions outlined in European and American Standards, as well as those proposed by various researchers were found unsuitable for design of HSS CHS under torsion. Hence, two modified design equations based on continuous strength method and direct strength method has been proposed. The modified design methods were found to predict more accurate and reliable torsional capacities.
本文对高强度钢(HSS)圆形空心截面(CHS)构件在纯扭力作用下的性能进行了详细的数值研究。研究中考虑了三种等级的高强度钢,即 S700、S900 和 S1100。最初开发了有限元(FE)模型,并根据现有的测试结果进行了验证。此外,经过验证的有限元模型还被用于参数研究。参数研究考虑了不同厚度和直径的横截面以及不同等级的高速钢。然后利用参数研究得出的结果来评估钢材等级对极限和后极限扭转能力和变形形状的影响。此外,还研究了屈服强度与极限比率对归一化构件承载力的影响。此外,还根据 FE 生成的构件承载力评估了现有的纯扭转构件设计方程式的适用性。根据分析结果,发现欧洲和美国标准中概述的大多数设计预测以及不同研究人员提出的设计预测都不适合在扭转情况下设计 HSS CHS。因此,我们提出了基于连续强度法和直接强度法的两种修正设计公式。结果发现,修改后的设计方法能预测更准确、更可靠的抗扭能力。