A stochastic approach to damage evolution in die-cast zinc alloys

压铸锌合金损伤演化的随机方法

• 批准号: 312867041
• 负责人: Professorin Dr.-Ing. Kerstin Weinberg
• 金额: --
• 依托单位: Department Maschinenbau
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 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/312867041?language=en
• 关键词: stochastic; approach; damage; evolution; die

The goal of the proposed research project is to develop a method for predicting the influence of material damage and mechanical load on the life expectation of a typical industrial component. Exemplarily we consider window hardware made of ZAMAK, a zinc alloy which is typically die-cast and widely used for load-bearing parts. New designs, like large glass facades and hidden pivot architecture, require these parts to be small but safe over a long period of time.In the first funding period we focused on the microstructure of the ZAMAK alloy and studied the evolution of defects as a result of fluctuations and deterministic mechanical stresses.In the advised second funding period we scrutinize the structural response of the die-cast component under effects of distributed defects in the material and of uncertain loading conditions. Despite of the widespread use there are only few reliable data available regarding the long term behavior of ZAMAK components. The very high mechanical properties diminish in the course of the component's life. This motivates us to study the loss of mechanical strength in ZAMAK as a result of distributed defects in the material and of uncertain loading conditions. Especially the misuse of the window components in certain situations and the resulting high stresses under uncertain inputs will be considered in this project. To achieve this we will employ a multi-fidelity sampling-based approach.The general idea of incorporating models with different levels of fidelity is based on the definition of surrogate low-fidelity models. Most of the sampling is then done with these cheap, approximate models. To account for the discrepancy between the low-fidelity and the real, high-fidelity solution, a Bayesian regression is employed on a training sample. Then it is possible to use the correlation to gain a probability of the failure within the high-fidelity model.Summarizing we state that uncertain material properties, environmental effects, perturbations in the production process combined with uncertain loading conditions results in a large variations of limit loads and life-expectation of die-cast ZAMAK components.As the result of this research the decay of ZAMAK's mechanical strength andload carrying capacity will be predicted. Prediction is meant here in the sense that incomplete and uncertain information about the problem is accounted for and that probability distributions or error bars on mean values are provided as simulation results.

提出的研究项目的目标是开发一种方法来预测材料损伤和机械载荷对典型工业部件预期寿命的影响。例如，我们考虑由ZAMAK制成的窗户硬件，ZAMAK是一种锌合金，通常是压铸的，广泛用于承重部件。新的设计，如大型玻璃幕墙和隐藏的枢轴建筑，要求这些部分很小，但在很长一段时间内是安全的。在第一个资助期，我们专注于ZAMAK合金的微观结构，并研究了波动和确定性机械应力导致缺陷的演变。在建议的第二个资助期，我们仔细研究了压铸部件在材料分布缺陷和不确定加载条件下的结构响应。尽管广泛使用，但关于ZAMAK组件的长期行为，只有少数可靠的数据可用。极高的机械性能在部件的使用寿命中逐渐降低。这促使我们研究ZAMAK中由于材料中的分布缺陷和不确定加载条件而导致的机械强度损失。特别是在某些情况下，窗构件的误用以及在不确定输入下产生的高应力将在本项目中得到考虑。为了实现这一点，我们将采用基于多保真度采样的方法。合并具有不同保真度的模型的一般思想是基于替代低保真度模型的定义。大多数的抽样都是用这些便宜的近似模型来完成的。为了解释低保真度和真实的高保真度之间的差异，在训练样本上使用贝叶斯回归。然后，可以使用相关性来获得高保真模型内失效的概率。综上所述，不确定的材料特性、环境影响、生产过程中的扰动以及不确定的加载条件导致ZAMAK压铸件的极限载荷和预期寿命发生很大变化。根据研究结果，对ZAMAK的机械强度和承载能力的衰减进行预测。在这里，预测是指考虑到问题的不完整和不确定信息，并提供均值的概率分布或误差条作为模拟结果。