HyTop: Development of a coupled topology optimization method for injection-molded, short fiber-reinforced polymer-metal hybrid composites to support the product engineer in design synthesis

本研究项目的目的是开发一种拓扑优化方法，以优化短纤维增强热塑性塑料(SFT) -金属混合结构，考虑热致收缩，由此产生的残余应力和注射成型过程中的局部各向异性材料特性。由于破坏时的最大力对混合动力结构的设计具有决定性作用，因此在优化时应使其最大化。正如之前的研究表明的那样，对于给定的聚合物基体和假设的粘附行为，金属插入物的形状对聚合物-金属杂化复合材料的力-位移行为起决定性作用。因此，所研究的拓扑优化方法应优化金属镶块的几何形状，并考虑以下几个方面：1)最终镶块的几何形状；2)最终镶块中的空腔被sft分量迭代填充。此外，拓扑优化方法在迭代过程中不仅要考虑sft矩阵，还要考虑金属的材料特性。为此，将文献中描述的用于模拟热学和力学行为的模型结合起来。除了荷载相关的应变和应力外，SFT结构中的残余应力也应考虑在内。代表所考虑的混合结构的两种材料，钢嵌件根据材料HC420LA建模，周围的SFT基体根据玻纤增强量为20、40和60体积%的热塑性聚丙烯建模。对于sft -金属混合结构设计的拓扑优化方法的发展，可以推导出以下子目标：•研究适合的建模方法，用于拓扑优化结构模型中sft -矩阵的力学和热性能的模拟映射•研究拓扑优化方法中金属插入物与sft -矩阵之间粘接区域的不同建模方法•研究一种用于sft -金属混合结构设计的方法研究了基于灵敏度的拓扑优化过程对sft -金属混合结构寻形优化的不同适应方法。推导了拓扑优化方法的设计准则，并在拓扑优化方法中引入了相应的边界条件(如最小半径、最小空腔尺寸)

The aim of this research project is the development of a topology optimization method for the optimization of short-fiber reinforced thermoplastic (SFT) -metal hybrid structures under consideration of thermally induced shrinkage, resulting residual stresses and local anisotropic material properties from the injection molding process. Since the maximum force in the event of failure is decisive for the design of the hybrid structure, it should be maximized in the optimization. As could be shown in previous studies, the shape of the metal insert is decisive for the force-displacement behavior of the polymer-metal hybrid composite for a given polymer matrix and assumed adhesion behavior. Therefore, the topology optimization method to be investigated should optimize the geometry of the metal insert and consider the following aspects: 1) the resulting geometry of the insert and 2) the filling of the resulting cavities in the insert with the SFT-component iteratively. Furthermore, the topology optimization method should consider the material properties of the metal as well as the SFT-matrix in the iterations. For this purpose, models described in the literature for simulating the thermal and mechanical behavior are to be integrated. In addition to the load-dependent strains and stresses, residual stresses in the SFT structure should also be taken into account. Representing the two materials of the considered hybrid structure, the steel insert is modelled according to the material HC420LA and the surrounding SFT matrix according to the thermoplastic polypropylene with variable glass fiber reinforcement content of 20, 40 and 60 volume-%.The following subgoals can be derived for the development of the topology optimization method for the design of SFT-metal hybrid structures:• Investigation of suitable modelling approaches for the simulative mapping of the mechanical and thermal properties of the SFT-matrix in the structural model for topology optimization• Investigation of different modeling approaches of the cohesive zone between metal insert and SFT-matrix in the topology optimization method• Investigate a method for automatically building the structural model for topology optimization, including filling the gaps in the metal insert with the complementary material• Investigation of different approaches for the adaptation of the sensitivity-based topology optimization process for the optimization of the SFT-metal hybrid structures in shape finding• Derivation of design guidlines and implementation of corresponding boundary conditions into the topology optimization method (e.g. minimum radii, minimum cavity size)