Full-field elasto-plasticity in dissimilar welded joins

由于焊接性能的不确定性，焊接性能的设计规范过于保守。重要的是，标准测试不适用于所涉及的复杂应力状态和连接的高度可变几何形状，例如t形连接。这是一个空间复杂的问题，适合于空间解决的全场变形测量。然而，我们迫切需要数值方法来解释实验数据，以便提取有用的参数，为部件设计提供信息。该项目的目的是开发集成的实验建模方法与数字图像相关（DIC）和虚拟场方法（VFM），以提取融合相关的不相似连接的全场变形行为。这将通过发展现有的数值方法来实现，通过控制应力集中器从不同的不同连接几何形状中提取弹塑性本构参数和真实应力-应变数据，以反映托克马克工程相关情况。这个博士项目将推动VFM参数化自动检测不同焊接连接中的变形区域。与有限元分析相比，VFM的速度高达125倍，因为它不需要正演建模，迭代地解决非线性问题平衡方程的弱形式。

Design codes for weld properties are over-conservative due to uncertainty in performance. Importantly, standard tests are not suitable for the complex stress states involved and the highly variable geometry of joins, e.g. T-joins. This is a spatially complex problem that lends itself to spatially-resolved full-field measurements of deformation. However, we urgently require numerical methods to interpret the experimental data for useful parameter extraction to inform component design. The purpose of this project is to develop integrated experimental-modelling methods with Digital Image Correlation (DIC) and the Virtual Fields Method (VFM) for extracting the full field deformation behaviour of fusion-relevant dissimilar joins. This will be achieved through the development of existing numerical methods to extract elasto-plastic constitutive parameters and true stress-strain data from varied dissimilar join geometry with controlled stress concentrators to reflect tokomak engineering-relevant situations.This PhD project will push VFM parameterisation towards the automatic detection of deformation zones within dissimilar welded joins. In comparison to finite element analyses, the VFM is up to 125 times faster as it requires no forward modelling, iteratively solving the weak form of the equilibrium equations for non-linear problems.