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,Thin-Walled Structures 3 篇
A three-dimensional micropolar beam model with application to the finite deformation analysis of hard-magnetic soft beams
Farzam Dadgar-Rad, Amirreza Hemmati, Mokarram Hossain
doi:10.1016/j.ijsolstr.2024.112662
三维微极梁模型及其在硬磁软梁有限变形分析中的应用
The main purpose of this contribution is to develop a three-dimensional (3D) nonlinear beam model based on the micropolar continuum theory. To do so, a kinematic model based on the deformation of three directors and accounting for the micro-rotation tensor of the micropolar theory is introduced. One of the main characteristics of the present beam model is that 3D constitutive equations without any modification can be directly used in the formulation. Furthermore, it is known that a body couple field is induced in hard-magnetic soft materials (HMSMs) when subjected to external magnetic fluxes. Therefore, the stress tensor in HMSMs is asymmetric, in general. Since the asymmetry of stress is one of the main features of the micropolar theory, the present formulation can be used for analyzing the deformation of beams made of HMSMs. Accordingly, the virtual external work of the present model is formulated so that it accounts for the contribution from uniform or constant-gradient external magnetic fluxes on the beam. Moreover, a Total Lagrangian (TL) nonlinear finite element (FE) formulation to provide numerical solutions of the related problems is developed. Several numerical examples are solved to investigate the capability of the developed formulation. It is shown that the present formulation can model the size-dependent behavior of beam-like structures if the material length-scale parameter of the micropolar constitutive model is comparable to the thickness of the beam. Moreover, the proposed model can successfully predict the finite deformation of 3D beams made of HMSMs subjected to magnetic loading.
本文的主要目的是建立基于微极连续统理论的三维(3D)非线性梁模型。为此,引入了一个基于三个方向的变形并考虑微极理论的微旋转张量的运动学模型。该梁模型的一个主要特点是无需任何修改即可直接使用三维本构方程。此外,已知硬磁软材料(HMSMs)在外加磁场作用下会产生体偶场。因此,在一般情况下,HMSMs中的应力张量是不对称的。由于应力的不对称性是微极理论的主要特征之一,因此本文的公式可以用于分析由微极材料制成的梁的变形。因此,本模型的虚外功可以考虑均匀或等梯度外磁通量对束流的贡献。此外,还建立了一个全拉格朗日(TL)非线性有限元(FE)公式,提供了相关问题的数值解。通过几个数值算例验证了所建立的公式的有效性。结果表明,如果微极性本构模型的材料长度尺度参数与梁的厚度相当,则该公式可以模拟类梁结构的尺寸依赖性行为。此外,所提出的模型可以成功地预测磁载荷作用下由hmsm制成的三维梁的有限变形。
A new methodology for anisotropic yield surface description using model order reduction techniques and invariant neural network
Chady Ghnatios, Oana Cazacu, Benoit Revil-Baudard, Francisco Chinesta
doi:10.1016/j.jmps.2024.105542
基于模型降阶和不变神经网络的各向异性屈服面描述新方法
In this paper, we present a general methodology that we call spectral neural network (SNN) which enables to generate automatically knowing a few datapoints (eight at most), a sound and plausible yield surface for any variations of a given anisotropic material, e.g. batches of the same material or same type of material produced by a different supplier. It relies on the use of a reliable parametrization of a performant analytic orthotropic yield function for the generation of a large database of yield surface shapes and the singular value decomposition method to create a reduced basis. For a specific material, a surrogate model for the reduced basis coordinates is further constructed using few additional datapoints. The dense neural network is built such as to ensure that the invariance requirements dictated by the material symmetry as well as the convexity of the yield surface are automatically enforced. The capabilities of this new methodology are demonstrated for hexagonal closed packed materials titanium materials, which are known to be particularly challenging to model due to their anisotropy and tension-compression asymmetry. Furthermore, we show that the SNN methodology can be extended such as to include variations of multiple materials of vastly different plastic behavior and yield surface shapes. The in-depth analysis presented reveals the benefits and limits of the hybrid data-driven models for description of anisotropic plasticity.
在本文中,我们提出了一种通用的方法,我们称之为光谱神经网络(SNN),它能够自动生成知道几个数据点(最多八个),对于给定各向异性材料的任何变化,例如,由不同供应商生产的相同材料或相同类型的材料的批次,合理且合理的屈服面。它依赖于使用可靠的参数化高性能的解析正交各向异性屈服函数来生成屈服曲面形状的大型数据库,并使用奇异值分解方法来创建约简基。对于特定材料,使用少量附加数据点进一步构建简化基坐标的代理模型。建立了密集神经网络,以确保自动执行材料对称性和屈服面凹凸性所决定的不变性要求。这种新方法的能力在六边形封闭填充材料钛材料中得到了证明,由于其各向异性和拉伸压缩不对称性,这种材料的建模特别具有挑战性。此外,我们表明SNN方法可以扩展,例如包括多种具有不同塑性行为和屈服面形状的材料的变化。深入的分析揭示了混合数据驱动模型描述各向异性塑性的优点和局限性。
Modeling electromechanical behaviors of soft conductive composites embedded with liquid metal fibers
Quang-Kha Nguyen, Pu Zhang
doi:10.1016/j.mechmat.2024.104920
嵌入液态金属纤维的软导电复合材料机电行为建模
Soft conductive materials are key components of soft electronics, sensors, actuators, and wearable devices. The electrical conductivity matrix or tensor of soft conductive materials is usually deformation-dependent, but there is a lack of constitutive modeling work on it. To fill this knowledge gap, we consider a soft conductive composite embedded with liquid metal fibers as an example. The difference between the material conductivity and spatial conductivity is clarified briefly. In addition, we devise two constitutive models for the deformation-dependent conductivity tensors. These two models are equivalent but in different formats, one using stretch ratios and the other using invariants. Besides the conductivity models, a transversely isotropic hyperelastic model is also presented to model the mechanical behaviors. These analytical models are fitted and validated using data from multiphysics computational modeling on representative volume elements. Note that the proposed models can also be used for other soft conductive materials as well as thermal conductivity modeling.
软导电材料是软电子、传感器、执行器和可穿戴设备的关键部件。软导电材料的导电性矩阵或张量通常是与变形相关的,但缺乏对其进行本构建模的工作。为了填补这一知识空白,我们以嵌入液态金属纤维的软导电复合材料为例。简要阐明了材料电导率与空间电导率的区别。此外,我们设计了变形相关的导电性张量的两个本构模型。这两个模型是等价的,但格式不同,一个使用拉伸比,另一个使用不变量。除了电导率模型外,还提出了横向各向同性超弹性模型来模拟力学行为。这些分析模型是用代表性体元的多物理场计算建模数据拟合和验证的。请注意,所提出的模型也可用于其他软导电材料以及导热性建模。
Parameter optimization of friction stir spot welded Al 6061 and CFRTP PA6 with surface treatment and interfacial adhesion
Yu Guo, Haibin Zhao, Caijiao Ai, Jingjing Zhao, Hao Su, Ji Chen, Guoqun Zhao
doi:10.1016/j.tws.2024.111585
Al 6061与CFRTP PA6搅拌摩擦点焊表面处理及界面附着力参数优化
The multiple material design of lightweight structural components of new energy vehicles imposes high demands on the joint of Al alloy and CFRTP composite. This study explored the fabrication of high joint strength between Al alloy 6061 and CFRTP PA6 composites through the laser ablation on Al alloy surface and friction stir spot welding (FSSW) process. By experimental optimization of the FSSW parameters, including rotational speed, displacement, and dwelling time, a remarkable tensile shear force of 10.282 kN was achieved under the rotational speed of 2000 rpm, displacement of 3 mm, and dwelling time of 10 s. The interfacial morphology of the Al alloy/CFRTP joint was characterized in detail. The microstructure analysis revealed a number of physical anchoring areas formed at the joint interface of laser-ablated Al alloy and CFRTP PA6. The PA6 resin of the CFRTP could be fully melted and effectively fill the grooves on the laser-ablated Al alloy surface due to the compression load and heat output at a high rotational speed and dwelling time.
新能源汽车轻量化结构件的多材料设计对铝合金与CFRTP复合材料的接合提出了很高的要求。本研究探讨了采用铝合金表面激光烧蚀和搅拌摩擦点焊(FSSW)工艺制备高强度铝合金6061与CFRTP PA6复合材料的结合。通过对FSSW的转速、位移和停留时间等参数进行实验优化,在转速为2000 rpm、位移为3 mm、停留时间为10 s的条件下,获得了10.282 kN的显著拉伸剪切力。对铝合金/CFRTP接头的界面形貌进行了详细的表征。显微组织分析表明,激光烧蚀铝合金与CFRTP PA6的接合界面处形成了大量的物理锚定区。CFRTP的PA6树脂在高转速和停留时间下的压缩载荷和热输出可以充分熔化并有效填充激光烧蚀铝合金表面的凹槽。
A series of auxetic metamaterials with negative thermal expansion based on L-shaped microstructures
Qiao Zhang, Yuxin Sun
doi:10.1016/j.tws.2024.111596
基于l型微结构的一系列负热膨胀的消热超材料
Mechanical metamaterials are facing various multi-functional requirements. In this study, a series of auxetic metamaterials with enhanced negative thermal expansion and improved stiffness are proposed. These metamaterials consist of four novel L-shaped microstructures connected in various clockwise or counterclockwise directions. Two length ratios and four angle parameters are utilized to define the geometry of these metamaterials. Both analytical analysis and validated numerical homogenization methods are employed to determine their effective thermoelastic properties, including effective Young's modulus, Poisson's ratio, and coefficient of thermal expansion. It is demonstrated that tailoring these microstructural geometries can modulate the effective thermoelastic properties of these metamaterials accordingly. By appropriately tailoring the geometric parameters, these metamaterials exhibit increased effective stiffness as well as more pronounced auxeticity and negative thermal expansion compared to traditional triangle and trapezoid microstructures. Notably, the in-plane effective anisotropic or isotropic Poisson's ratio and coefficient of thermal expansion can be adjustable over a broader range from negative to positive values. High stiffness, High strength, and near-zero thermal expansion can be achieved concurrently in these metamaterials, which is very conducive for structural designing in thermal environments. These metamaterials with a coupled design of stiffness, thermal expansion, and Poisson's ratio hold significant potential for advancing applications in satellite platforms, space structures, composite sandwiches, and precision equipment.
机械超材料正面临着各种各样的多功能需求。在本研究中,提出了一系列增强负热膨胀和提高刚度的增氧超材料。这些超材料由四个新颖的l形微结构组成,以不同的顺时针或逆时针方向连接。利用两个长度比和四个角度参数来定义这些超材料的几何形状。采用解析分析和经过验证的数值均匀化方法确定了其有效热弹性特性,包括有效杨氏模量、泊松比和热膨胀系数。结果表明,调整这些微观结构几何形状可以相应地调节这些超材料的有效热弹性性能。通过适当调整几何参数,与传统的三角形和梯形微结构相比,这些超材料表现出更高的有效刚度、更明显的塑性和负热膨胀。值得注意的是,平面内有效各向异性或各向同性泊松比和热膨胀系数可以在更宽的范围内从负值到正值进行调节。这些超材料可以同时实现高刚度、高强度和近零热膨胀,这对热环境下的结构设计非常有利。这些具有刚度、热膨胀和泊松比耦合设计的超材料在卫星平台、空间结构、复合夹层和精密设备中具有巨大的应用潜力。
Forced vibration response prediction of Miura-ori core sandwich panel with impact defects
Changyuan Ge, Caihua Zhou, Shijian Xiao, Mingfa Ren, Bo Wang
doi:10.1016/j.tws.2024.111597
含冲击缺陷的Miura-ori芯芯夹芯板的强迫振动响应预测
Miura-ori core sandwich panels have great application potential in aviation aircraft. Subject to the impact and vibration loads, the small impact defect will increase the dynamic stress, resulting in fatigue failure. Moreover, the Miura creases complicate the impact deformation, which is extremely time-consuming to analysis the dynamic stress only through simulation. Therefore, a rapid dynamic stress prediction method for Miura-ori core sandwich panels is first proposed based on the predicted impact deformation by arbitrary defects in this paper. The dynamic stress of sandwich panels could be directly calculated with few numerical results by establishing the relationship with impact deformation in advance. The vibration mechanism of sandwich panels with defects is revealed. Although the deformation area is below 32.1% of Miura cell projection area, the dynamic stress will increase by 1.984-2.635 times with different defects. The impact deformation is predicted by the geometric relationship of Miura creases and material properties, and the prediction errors of hemispherical and drilling defects with arbitrary defect positions are below 12.5% and 10.6%, respectively. Taking two types of defects (hemispherical and drilling defects), different defect depths and positions into consideration, the prediction errors of maximum dynamic stress are from -7.9% to 16.8% compared to simulation.
三浦ori芯芯夹芯板在航空飞机上具有很大的应用潜力。在冲击和振动载荷作用下,微小的冲击缺陷会使动应力增大,导致疲劳失效。此外,Miura折痕使冲击变形复杂化,仅通过仿真分析动应力非常耗时。因此,本文首次提出了一种基于任意缺陷冲击变形预测的Miura-ori芯芯夹层板动态应力快速预测方法。通过预先建立夹层板的动应力与冲击变形的关系,可以直接计算夹层板的动应力,而计算结果很少。揭示了含缺陷夹层板的振动机理。虽然变形面积小于Miura胞体投影面积的32.1%,但不同缺陷的动应力会增加1.984-2.635倍。利用Miura折痕与材料性能的几何关系预测冲击变形,对于任意缺陷位置的半球形缺陷和钻孔缺陷,预测误差分别在12.5%和10.6%以下。考虑两种缺陷类型(半球形缺陷和钻孔缺陷)、不同缺陷深度和位置,最大动应力预测误差为-7.9% ~ 16.8%。