The study is devoted to geometrically non-linear modelling of viscoplastic structures with residual stresses. We advocate and develop a special approach to residual stresses based on the transition between reference configurations. The finite strain kinematics of the viscoplastic material is modelled by the multiplicative decomposition of the deformation gradient tensor. Numerical algorithms originally developed for unstressed materials are extended to materials with pre-stresses. Owing to the weak invariance of constitutive equations, the incorporation of pre-stresses happens without additional costs. Thus, the advocated approach is especially efficient. A novel experimental/theoretical method for assessment of residual stresses in welded structures is presented; the method combines advantages of purely experimental and theoretical approaches. To demonstrate the applicability of the proposed procedure, we simulate plate welding. As an example we show that the procedure allows to extrapolate the filed of residual stresses away from the measurement points. As another example, we address the reduction of weldment-related residual stresses by mechanical treatment.
A link between microstructure evolution and macroscopic response in elasto-plasticity: formulation and numerical approximation of the higher-dimensional Continuum Dislocation Dynamics theory
Dislocation interactions during low-temperature plasticity of olivine strengthen the lithospheric mantle
岩石圈的强度通常是基于稳态流动的本构方程建模的。然而，岩石圈挠曲模型揭示了岩石圈强度的差异，这些差异很难根据这种流动定律来协调。最近的流变学数据从橄榄石的低温变形实验表明，这种差异可能在很大程度上解释了应变硬化。力学数据的细节，特别是存储在样品中的温度无关的背应力的影响，表明应变硬化在橄榄石中发生主要是由于位错之间的长程弹性相互作用。这些解释提供了一个新的流动定律，包括发展的背应力硬化的基础。在这里，我们测试这一假设，通过检查橄榄石样品的微观结构变形塑性在室温下，无论是在变形DIA装置在差应力为< 4.3 GPa or in a nanoindenter at applied contact stresses of >10.2 GPa。高角分辨率电子背散射衍射图揭示了在两组样品中存在密度通常高于10 $^{14}$ m $^{-2}$的几何必需位错和大约1 GPa的残余应力的晶内不均匀性.扫描透射电子显微镜照片显示直位错沿滑移带排列，并与其他类型的位错相互作用，作为障碍。位错沿其滑移面的应力不均匀性和累积与位错间长程背应力引起的应变硬化一致。这些结果证实了支持低温塑性新流动定律的形式的力学数据，并提供了新的微观结构标准，用于识别这种变形机制在天然样品中的操作。
A Gibbs-potential-based framework for ideal plasticity of crystalline solids treated as a material flow through an adjustable crystal lattice space and its application to three-dimensional micropillar compression
