今日更新:International Journal of Solids and Structures 1 篇,Journal of the Mechanics and Physics of Solids 1 篇,Thin-Walled Structures 1 篇
A continuum model for the mechanics of elastomeric sheets reinforced with extensible bidirectional fibers resistant to lateral pressure
Wenhao Yao, Tahmid Rakin Siddiqui, Chun I.L. Kim
doi:10.1016/j.ijsolstr.2024.113002
用可拉伸双向纤维增强弹性体板抗侧压力学的连续体模型
We investigate the concurrent three-dimensional (in-plane and out-of-plane) deformations of fiber-reinforced composite (FRC) sheets undergoing lateral pressure. This involves the utilization of the Neo-Hookean strain energy model for the matrix material and computing the strain energy of bidirectional fibers by accounting for the stretching, bending, and twisting responses of the fibers. The kinematics of FRC are formulated within the framework of differential geometry on FRC surfaces, including the computations of the first and second gradient of deformation. By employing the variational principles, we derive the Euler equations describing the mechanics of the fiber–matrix composite system subjected to lateral pressure. The resulting three-dimensional continuum model theoretically predicts the deformation of the matrix material and it is found that the maximum deformation of matrix material occurs in the diagonal direction of the domain, yet, the center of the domain suffers weak in-plane deformation because of surface tension equilibrium. In addition, the stretching, bending, and twisting kinematics of fiber units are computed to investigate the effects of the individual fiber’s kinematics on the overall deformation of fiber meshwork. Lastly, it is found that the lateral pressure on the FRC surface induces fiber flexure in the vicinity of domain boundaries and fiber stretch inside the domain, corresponding to the intensified shrinking strain near the edges and stretching strain in the middle of the domain. The theoretical results provide phenomenologically meaningful insights into comprehending the damage patterns of the fiber-reinforced building material, the hemispherical dome shaping results of bamboo Poly (lactic) acid (PLA) composites and the out-of-plane deformation of woven fabric.
我们研究了纤维增强复合材料(FRC)板在侧向压力下的三维(面内和面外)变形。这涉及到对基体材料的Neo-Hookean应变能模型的利用,并通过考虑纤维的拉伸、弯曲和扭转响应来计算双向纤维的应变能。在FRC曲面的微分几何框架下,建立了FRC的运动学模型,包括第一和第二变形梯度的计算。利用变分原理,导出了描述纤维基复合材料在侧向压力作用下力学特性的欧拉方程。所得的三维连续体模型从理论上预测了基体材料的变形,发现基体材料的最大变形发生在对角线方向,而区域中心由于表面张力平衡而发生微弱的面内变形。此外,还计算了纤维单元的拉伸、弯曲和扭转运动学,以研究单个纤维的运动学对纤维网整体变形的影响。最后,发现FRC表面的侧压力导致区域边界附近的纤维挠曲和区域内的纤维拉伸,对应于区域边缘附近的收缩应变和区域中部的拉伸应变的增强。理论结果为理解纤维增强建筑材料的损伤模式、竹聚乳酸(PLA)复合材料的半球形成形结果以及机织物的面外变形提供了现象学上有意义的见解。
Criterion for unhomogeneous yielding of porous materials
R. Vigneshwaran, A.A. Benzerga
doi:10.1016/j.jmps.2024.105804
多孔材料非均匀屈服准则
A criterion is developed for the unhomogeneous yielding of materials containing arbitrarily oriented ellipsoidal voids. The criterion is built upon classical estimates for pure pressure and pure shear. A data-driven approach is then followed to incorporate the effects of void shape and orientation. A large number of micromechanical unit cell results are used to calibrate the yield criterion. A key feature of the criterion is that it predicts a significant reduction of the effective shear yield strength due to mere void inclination, with the reduction increasing with the void dimension perpendicular to the shear. The coupling between tension and shear deformation results in an apparent rotation of the yield surface, which provides a sound micromechanical basis for predicting void closure in shear among other new features. Once supplemented with evolution equations of relevant internal parameters, the resulting constitutive formulation will enable ductile failure simulations heretofore impossible to carry out on a sound physical basis for general loading conditions.
提出了含有任意取向椭球体空洞的材料的非均匀屈服判据。该准则是建立在纯压力和纯剪切的经典估计基础上的。然后采用数据驱动的方法来结合空隙形状和方向的影响。大量的微力学单胞结果被用来校准屈服准则。该准则的一个关键特征是,它预测了有效抗剪屈服强度的显著降低,因为仅仅是空洞倾斜,随着垂直于剪切的空洞尺寸的增加,这种降低也在增加。拉伸和剪切变形之间的耦合导致屈服面出现明显的旋转,这为预测剪切过程中孔隙闭合等新特征提供了良好的微观力学基础。一旦补充了相关内部参数的演化方程,得到的本构公式将使迄今为止不可能在一般加载条件下在可靠的物理基础上进行的延性破坏模拟成为可能。
Controlled swelling-induced shape change of soft gel filled structures
Silvia Monchetti, Roberto Brighenti, Tamara Hanuhov, Noy Cohen
doi:10.1016/j.tws.2024.112280
控制膨胀诱导的软凝胶填充结构的形状变化
Gels are polymers that can imbibe large amounts of solvent and generate large volumetric deformations in a process commonly termed swelling. The swelling-induced deformations can be harnessed to produce pressure against surrounding elastic elements, and therefore lead to spatial shape changes without the need for an external energy source. In the present paper, we consider a thin cylindrical elastic tube that encapsulates a gel and deforms in response to the swelling-induced forces. It is expected that by controlling the spatial stiffness distribution of the tube, the deformed swelling-induced shape can be programmed. We exploit this simple idea to obtain controlled shape change driven by the large volumetric expansion of gels. To this end, we train a machine learning algorithm through many FE simulations that enable solving the inverse problem: for any prescribed swelling-induced target shape, the algorithm provides the spatial stiffness distribution of the thin tube. The results confirm that precise controlled shape change is achievable by exploiting the large swelling-induced volumetric deformations in an autonomous manner (i.e. without the need for any external energy source). This work paves the way for new perspectives in the design of shape-change systems based on the simple yet proper elastic distribution of confining structures.
凝胶是一种聚合物,它可以吸收大量的溶剂,并在通常称为膨胀的过程中产生大量的体积变形。膨胀引起的变形可以用来对周围的弹性元件产生压力,从而导致空间形状的变化,而不需要外部能源。在本论文中,我们考虑了一个薄的圆柱形弹性管,它封装了凝胶,并在响应膨胀诱导的力时变形。期望通过控制管材的空间刚度分布,实现管材膨胀变形形状的编程。我们利用这个简单的想法来获得由凝胶的大体积膨胀驱动的可控形状变化。为此,我们通过许多有限元模拟训练了一种机器学习算法,该算法能够解决反问题:对于任何规定的膨胀诱导目标形状,该算法提供了薄管的空间刚度分布。结果证实,通过以自主的方式(即不需要任何外部能源)利用由膨胀引起的大体积变形,可以实现精确控制的形状变化。这项工作为基于简单而适当的约束结构弹性分布的形状变化系统设计的新视角铺平了道路。