Thermo-mechanical analysis of propagating instabilities in metals - from experiments to reliable numerical prediction

材料的不稳定性会显著影响相应金属的延展性、强度和抗疲劳性等性能。金属材料不稳定性的典型例子是相变和局域化现象。后者是本提案的重点，即以Lueders带和Portevin-Le Chatelier(PLC)效应的形式传播材料不稳定性。这种与应变时效有关的塑性变形带的出现和演化取决于应变速率和温度。了解和可靠地预测传播的Lueders和PLC带对于显示这些现象的材料制成的部件和结构的资源效率设计是至关重要的。这需要先进的热力学模型，一方面捕捉到这些带在不同加载速率和温度水平下的起始和演化，另一方面需要在参数识别的背景下进行高级实验研究。在不同的加载速率和温度水平下，基于全场位移和温度数据来识别的、可靠且同时预测Lueders带和PLC效应的统一模型在文献中是不存在的。这一建议的目标是填补这一空白，并建立这种模型，并在包括全部现场数据的实验基础上进行识别。

Material instabilities significantly affect the respective metal’s properties such as ductility, strength and fatigue resistance. Typical examples of material instabilities in metals are phase-transition and localisation phenomena. The latter are in the focus of this proposal, namely propagating material instabilities in the form of Lueders bands and the Portevin-Le Chatelier (PLC) effect. The occurrence and evolution of such bands of plastic deformation, related to so-called strain aging, are known to depend on both strain rate and temperature. The understanding and reliable prediction of propagating Lueders and PLC bands are of key importance for resource-efficient design of components and structures made of materials showing these phenomena. This requires advanced thermo-mechanical models that capture the initiation and evolution of these bands at different loading rates and temperature levels on the one hand, and advanced experimental investigations in the context of parameter identification on the other. A unified model that captures the reliable and simultaneous prediction of Lueders bands and the PLC effect at different loading rates and temperature levels, and which is identified based on full field displacement and temperature data, is not available in the literature. The goal of this proposal is to fill this gap and to establish such model together with identification based on experiments including full field data.