Numerical Simulation of Limit Load Behaviour for Welded Aluminium Structures Based on Materials Knowledge

基于材料知识的焊接铝结构极限载荷行为数值模拟

• 批准号: 290068716
• 负责人: Dr.-Ing. Michael Reich
• 金额: --
• 依托单位: Lehrstuhl für Werkstofftechnik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2016
• 资助国家: 德国
• 起止时间: 2015-12-31 至 2019-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/290068716?language=en
• 关键词: Numerical; Simulation; Limit; Load; Behaviour

The currently most important lightweight material is aluminium and its alloys and is used successfully with increasing tendency. It is important to ensure that the developed structures fulfil their task safely over the period of use. In this consideration accident cases and thus, for example caused structural failure must be taken into account. As with welded steel constructions, the limit load behaviour is dominated by the failure of joints and adjacent areas even with the use of aluminium alloys. The proposed research project aims at the development of new damage models for aluminium welds under consideration from material- and production-technical principles and their testing in global structural models. For this purpose, welding time-temperature-precipitation and dissolution diagrams are created by calorimetry and dilatometry for the first time, as they are known, for example as welding TTT diagram for steels. The thermo-mechanical analysis in the quenching and deformation dilatometer enables the description of the influence of the detected phase changes on the mechanical properties. The results obtained therefrom are the basis for a calculation model of the welding process to determine structural properties, distortion and residual stresses based on the finite element method. With the aim to calibrate a criterion for the ductile fracture failure, the true stress-strain relations for the base material, the fusion zone and the HAZ should be determined by means of FE simulations of tensile tests on materials- and welded small samples. The dependence of the fracture strain from the stress state is determined by the use of different sharply notched test specimens. Following, the structural behaviour of welded X-sections will be investigated in detail both experimentally and numerically under axial compressive load. In addition to the recording of load-displacement curves and the detection of local deformations is desired to visually capture the fracture behaviour in the form of crack initiation and crack growth. The aim of the FE analyses is finally the coupling of the process simulation of the welding process with the limit load calculation for a sufficiently accurate determination of the energy absorption capacity of the welded structure, which considers in addition to the material properties distribution also the residual stress and distortion. The research project provides fundamental insights into the failure mechanism of welded aluminium structures and its numerical modelling, which are becoming increasingly important in the design.

当前最重要的轻质材料是铝及其合金，并以增加的趋势成功使用。重要的是要确保开发的结构在使用期间安全完成任务。在此考虑事故案件中，例如，必须考虑导致结构性故障。与焊接钢结构一样，即使使用铝合金，极限载荷行为也由关节和邻近区域的故障主导。拟议的研究项目旨在开发从材料和生产技术原理中考虑的铝焊缝的新损伤模型及其在全球结构模型中的测试。为此，焊接时间调节和溶解图是首次通过量热法和扩张法创建，例如，例如，作为钢的焊接TTT图。淬灭和变形扩张仪中的热机械分析能够描述检测到的相变量对机械性能的影响。从其中获得的结果是基于有限元方法确定结构特性，失真和残余应力的焊接过程计算模型的基础。为了校准针对延性裂缝失败的标准，应通过对材料和焊接小样品的抗张测试的Fe模拟来确定基础材料的真正应力 - 应变关系，融合区和HAZ应确定。裂缝应变与应力状态的依赖性取决于使用不同尖锐的测试样品。随后，将在轴向压缩负载下详细研究焊接X段的结构行为。除了记录载荷 - 位置曲线和局部变形的检测外，还需要以裂纹启动和裂纹生长的形式视觉捕获断裂行为。 Fe分析的目的最终是焊接过程的过程模拟与极限载荷计算的耦合，以充分准确地确定焊接结构的能量吸收能力，除了材料特性外，还考虑了残差。压力和失真。该研究项目提供了对焊接铝结构的故障机制及其数值建模的基本见解，这些结构在设计中变得越来越重要。