Analysis and evaluation of the effects of residual stresses on the damage evolution in intrinsically manufactured hybrid materials under static and cyclic loading

静态和循环载荷下残余应力对本质制造的混合材料损伤演化影响的分析和评估

• 批准号: 399304816
• 负责人: Professor Dr.-Ing. Thomas Niendorf
• 金额: --
• 依托单位: Lehrstuhl für Leichtbau im Automobil (LiA)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/399304816?language=en
• 关键词: Analysis; evaluation; effects; residual; stresses

Decrease of vehicles weight through lightweight design is a suitable approach to promote resource and fuel efficiency in the automotive sector. Due to their weight-specific high strength and stiffness, modern vehicle concepts increasingly make use of fiber-reinforced plastics (FRPs). Besides the solitary use of these FRP composites, application of hybrid structures in highly loaded parts of the vehicle is feasible. Time and cost efficient production of those hybrid structures can be realized by process induced bonding of metal and FRP. Such kind of intrinsic hybridization allows to significantly reduce the total number of processing steps. However, the interface between metal and FRP is the weakest link in these hybrids, as the different thermal expansion coefficients of fiber and metal lead to the evolution of residual stress upon cooling from processing temperature to room temperature. At critical areas of the component, these stresses can be relieved through localized delamination.In the first funding period of the project, residual stress states in intrinsically manufactured plastic-metal layered hybrid composites were investigated in depth. So far, the main focus was particularly on methodological questions concerning the experimental residual stress determination in layered composites. Furthermore, the effects of materials and process parameters on the resulting residual stress distributions were assessed. Multi-scale approaches using established simulation methods were developed and implemented for in-depth understanding of relevant phenomena. In the second funding period, the effects of manufacturing-induced residual stresses on the behavior of hybrid materials under mechanical loading will be studied. Damage evolution under static and cyclic loading will be in focus of these investigations. Additionally, relationships between residual stresses, defects and structural integrity will be established. With respect to the envisaged applications of hybrid material composites, effects of active fiber pre-stressing on the damage evolution are to be investigated in particular, taking the residual stress state into account.The analytical methods applied in the project will allow for the determination of the influence of residual stress on the damage behavior under mechanical (static and cyclic) loading. Moreover, the results obtained will be used to establish a knowledge base which, after completion of the project, will allow to avoid unfavourable residual stress states and promote favourable ones to be set through targeted parameter selection during production. Eventually, based on the investigations, a reliable and safe use of hybrid material composites in the envisaged fields of application will be ensured.

通过轻量化设计降低车辆重量是提高汽车行业资源和燃料效率的合适方法。由于其重量特定的高强度和刚度，现代车辆概念越来越多地使用纤维增强塑料（FRP）。除了单独使用这些FRP复合材料外，混合结构在车辆的高载荷部件中的应用是可行的。这些混合结构的时间和成本有效的生产可以通过金属和FRP的工艺诱导结合来实现。这种固有杂交允许显著减少处理步骤的总数。然而，金属和FRP之间的界面是这些混合物中最薄弱的环节，因为纤维和金属的不同热膨胀系数导致从加工温度冷却到室温时残余应力的演变。在该项目的第一个资助期内，对本机制造的塑料-金属层状混杂复合材料中的残余应力状态进行了深入研究。到目前为止，主要的重点是特别是在层状复合材料的残余应力测定实验的方法学问题。此外，材料和工艺参数对所得残余应力分布的影响进行了评估。为了深入了解相关现象，开发并实施了使用既定模拟方法的多尺度方法。在第二个资助期内，将研究制造引起的残余应力对混合材料在机械载荷下的行为的影响。静态和循环载荷下的损伤演化将是这些调查的重点。此外，将建立残余应力、缺陷和结构完整性之间的关系。对于混合材料复合材料的预期应用，需要特别研究活性纤维预应力对损伤演化的影响，并考虑残余应力状态。该项目中应用的分析方法将允许确定残余应力对机械（静态和循环）载荷下损伤行为的影响。此外，所获得的结果将用于建立知识库，在项目完成后，该知识库将允许避免不利的残余应力状态，并在生产期间通过有针对性的参数选择来促进有利的残余应力状态。最终，基于调查，将确保在设想的应用领域中可靠和安全地使用混合材料复合材料。