Mechanism-correlated characterization of the deformation and damage behavior of thermo-plastic-based fiber metal laminates for property-oriented process development

两阶段研究项目的目标是识别，分析和评估热塑性基纤维金属层压板的强度和耐久性的影响因素。第一个供资期侧重于材料开发和整合过程。在第二个资助期内，将通过演示部件研究成形技术对材料完整性和部件完整性的影响。根据现有技术，热固性基纤维金属层压件的疲劳强度特别地受到其分层行为的影响。因此，替代热塑性纤维金属层压板预期鉴定的主要目的是研究金属部件表面预处理的机械（喷砂）和化学（酸洗）方法对疲劳损伤的抑制作用。纤维增强聚合物（FRP）和铝层中的界面和微观结构的形成将通过材相学方法来确定，例如，光学显微镜（LiMi）、扫描（SEM）和透射电子显微镜（TEM）以及计算机断层扫描（CT）。将在准静态和循环试验中使用扩展的仪器监测与损坏有关的物理参数，例如电阻和声发射的变化，以确定主要损坏机制。为了更详细地分析损伤机制，准静态原位测试中材料体积的刚度梯度将通过CT使用数字体积相关（DVC）的新方法可视化。根据机械测试的结果，将制定工艺-结构-性能关系，并给出生产热塑性纤维金属层压板的工艺步骤参数化的建议。在第一个资助期结束时，对选定的纤维-金属层合板进行了基本表征，并系统地研究了其损伤行为。此外，合适的层压结构可用作成型工艺的起始材料，这些工艺将在第二个资助期内进行研究。在第二个资助期内，将通过一个成型的演示器来确定成型工艺对纤维-金属层压板材料性能的影响。将从受影响的区域切除标本，例如，通过纤维在弯曲半径上的重新排列。将根据机械和材相方面对这些样本进行分析。另一个焦点是扩展应力分布的产生，例如，通过在疲劳试验中叠加温度和湿度的影响，以研究材料在工作条件下的行为。

The objective of the two-phase research project is the identification, analysis and assessment of influencing factors on the strength and durability of thermoplastic-based fiber metal laminates. The first funding period focuses on material development and the consolidation process. In a second funding period, the effect of forming technology on material integrity as well as component integrity will be investigated by means of a demonstrator component. According to the state of the art, the fatigue strength of thermoset-based fiber metal laminates is influenced, in particular, by their delamination behavior. Therefore, primary objective for the intended qualification of alternative thermoplastic-based fiber metal laminates is the investigation on the restraint of fatigue damage as a result of mechanical (blasting) and chemical (pickling) methods for surface pretreatment of the metallic component. The interfacial and microstructure formation in the fiber-reinforced polymer (FRP) and aluminum layers will be determined by means of materialographic methods, e.g., light microscopy (LiMi), scanning (SEM) and transmission electron microscopy (TEM), as well as computed tomography (CT). The identification of dominant damage mechanisms will be carried out in quasi-static and cyclic testing using extended instrumentation for the monitoring of damage-related physical parameters, e.g. changes in electric resistance and acoustic emission. For a more detailed analysis of damage mechanisms, stiffness gradients in the material volume in quasi-static in-situ tests will be visualized via CT using the novel approach of digital volume correlation (DVC). Based on the results of mechanical testing, a process-structure-property relationship will be formulated and recommendations for the parameterization of the process steps for the production of thermoplastic-based fiber metal laminates will be given. At the end of the first funding period, selected fiber-metal laminates are fundamentally characterized and their damage behavior is investigated systematically. Furthermore, suitable laminate configurations are available as starting material for forming processes which are to be investigated in the second funding period. In the second funding period, the influence of forming processes on the material behavior of fiber-metal laminates is to be determined by means of a formed demonstrator. Specimens will be resected from areas which are influenced, e.g., by fiber rearrangements in bending radius. These specimens will be analyzed under mechanical as well as materialographic aspects. A further focus is the generation of extended stress distri-bution, e.g., by superimposed temperature and humidity influence in fatigue testing, in order to investigate the material behavior under operating conditions.