今日更新:Composite Structures 2 篇,Composites Part A: Applied Science and Manufacturing 1 篇
A multi-objective optimization approach to design bistable collapsible tubular mast
Flavia Palmeri, Susanna Laurenzi
doi:10.1016/j.compstruct.2024.118593
双稳折叠式管状桅杆的多目标优化设计方法
The collapsible tubular mast (CTM) is a deployable structure made of two omega shaped shells, with each omega composed of three arc segments. In the bistable CTM (Bi-CTM), in addition to the strain energy well associated with the stable deployed state, another strain energy well can be found corresponding to the stable coiled state. The arcs’ geometries influence the existence of the second strain energy well and the associated stable coiled radius, responsible for the boom’s packaging efficiency. Besides packaging efficiency, factors like bending stiffness are also contingent on the geometries of the arcs, leading to significant trade-offs among these metrics. In this work, we propose a multi-objective optimization (MOO) to find optimal compromises that balance these conflicting requirements of a CTM. Particularly, a coupling analytical models and evolutionary algorithms (EA) technique is presented, utilizing and bench-marking various state-of-the-art EAs. The MOO approach gives as output the Pareto front, a set of the non-dominated design points, which showcases different trade-offs solutions tailorable for specific space-applications. Different design points are presented and discussed based on higher-level considerations.
可折叠管状桅杆(CTM)是一种可展开结构,由两个欧米茄形壳体组成,每个欧米茄由三个弧段组成。在双稳态CTM (Bi-CTM)中,除了与稳定展开状态相对应的应变能井外,还可以找到与稳定盘绕状态相对应的应变能井。弧的几何形状影响第二应变能井的存在和相关的稳定盘绕半径,这是悬臂的包装效率的关键。除了封装效率,弯曲刚度等因素也取决于弧线的几何形状,导致这些指标之间的重大权衡。在这项工作中,我们提出了一个多目标优化(MOO)来找到平衡CTM这些冲突要求的最佳妥协。特别地,提出了一种耦合分析模型和进化算法(EA)的技术,利用各种最先进的EA并对其进行基准测试。MOO方法将帕累托前沿作为输出,这是一组非主导设计点,展示了针对特定空间应用量身定制的不同权衡解决方案。基于更高层次的考虑,提出并讨论了不同的设计点。
Fatigue delamination damage analysis in composite materials through a rule of mixtures approach
Alireza Taherzadeh-Fard, Sergio Jiménez, Alejandro Cornejo, Eugenio Oñate, Lucia Gratiela Barbu
doi:10.1016/j.compstruct.2024.118613
基于混合规则的复合材料疲劳分层损伤分析
The present study investigates delamination damage initiation and propagation within a homogenization theory of mixtures, using the concept of virtual layers and virtual interfaces. It eliminates spatial discretization of layers, introducing a resultant damage variable to capture structure’s bulk response under both monotonic and cyclic loads. Fatigue-induced deterioration is classified into sub-critical, critical, and over-critical stages based on interfacial stresses. Calibration is conducted employing the widely-available Wöhler curves for each loading mode independently. An advance-in-time strategy is included in the model to enhance the simulation speed. The reliability of the approach is assessed for crack initiation and propagation separately through standard test coupons, showing good correlation with experimental data in mode I, mode II, and mixed-mode loading conditions. Depending on the calibration procedure adopted, the model is applicable to a wide range of stress ratios. In addition, it could be integrated into any standard finite element framework using the desired number of elements through the thickness regardless of the physical amount of layers. This allows easy modification of stacking sequences or the number of layers within the constitutive law without mesh structure changes, facilitating simulation of large-scale composite laminates with minimal accuracy loss and reduced computational costs.
本研究利用虚拟层和虚拟界面的概念,在混合均匀化理论中研究分层损伤的产生和扩展。它消除了层的空间离散化,引入了一个综合损伤变量来捕捉结构在单调和循环荷载下的整体响应。根据界面应力,疲劳诱发劣化分为亚临界、临界和过临界阶段。校准是采用广泛可用的Wöhler曲线为每个加载模式独立进行的。模型中引入了超前策略,提高了仿真速度。通过标准试样分别对裂纹萌生和扩展进行了可靠性评估,在ⅰ型、ⅱ型和混合模态加载条件下,该方法与试验数据具有良好的相关性。根据所采用的校正程序,该模型适用于各种应力比。此外,它可以集成到任何标准的有限元框架中,使用所需的元素数量通过厚度,而不考虑层的物理量。这使得在不改变网格结构的情况下,可以轻松修改堆叠序列或本构律内的层数,从而以最小的精度损失和降低的计算成本促进大规模复合材料层压板的模拟。
Multiscale modelling of CFRP composites exposed to thermo-mechanical loading from fire
Lei Wan, Scott L.J. Millen
doi:10.1016/j.compositesa.2024.108481
火灾热机械载荷下CFRP复合材料的多尺度建模
Carbon fibre reinforced polymers (CFRP) are prone to structural damage during extreme events such as fire. Typically, modelling the effect of fire on CFRP structures is carried out through mesoscale analysis to predict overall structural performance. In this study, Finite Element (FE) modelling has been conducted to investigate the effects of fire on CFRP specimens at both meso- and micro-scales. The mesoscale analysis informs the microscale analysis to examine the effects of fire on each constituent of the material. A comparison of thermal analysis at the meso- and micro-scales reveals less than a 6% difference in the predicted node temperature. For the first time, fire-induced progressive failure analysis has been conducted on the fibres, matrix, and fibre/matrix interface of representative plies within the composite laminates. Fibre breakage, matrix cracking, and interface debonding were accurately captured using representative volume element (RVE) models under thermo-mechanical loading, showing qualitatively excellent agreement with experimental data.
碳纤维增强聚合物(CFRP)在火灾等极端事件中容易造成结构损坏。通常,模拟火灾对CFRP结构的影响是通过中尺度分析来预测整体结构性能的。在这项研究中,有限元(FE)模型已经进行了研究火灾对CFRP试样在中观和微观尺度的影响。中尺度分析通知微观尺度分析,以检查火对材料的每个组成部分的影响。中尺度和微观尺度的热分析比较表明,预测节点温度的差异不到6%。首次对复合材料层合板中具有代表性层的纤维、基体和纤维/基体界面进行了火致渐进破坏分析。采用代表性体积元(RVE)模型准确捕捉了热机械载荷下纤维断裂、基体开裂和界面剥离,与实验数据在质量上非常吻合。