Numerical Analysis of material uncertainties in components with microheterogeneous ranges

具有微异质范围的部件中材料不确定性的数值分析

• 批准号: 317072826
• 负责人: Dr. Carla Beckmann
• 金额: --
• 依托单位: Fraunhofer-Institut für Werkstoffmechanik (IWM)
• 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 2018-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/317072826?language=en
• 关键词: Numerical; Analysis; material; uncertainties; components

The objective of the current proposal is the development of a method for the numerically efficient determination and modelling of material uncertainties in lightweight structures consisting partially of stochastic microheterogeneous materials, e.g. solid foams. Such methods are required in the design structures and components, since classical deterministic concepts are inappropriate for statistically microheterogeneous bodies. For this reason, a probabilistic method shall be developed, using the example of a sandwich construction with a closed-cell foam core. This method will allow the determination of the effective material properties and the corresponding scatter on the base of the dispersed microstructural properties. The necessary input parameters such as cell size, shape and orientation of the cellular microstructure and the corresponding probability distributions can be obtained by computed tomography. In particular, a method shall be developed, accounting for the effect of microstructural anisotropy on the effective material properties. For the development of the probabilistic constitutive law based on microstructural simulations, an algorithm for generation of finite element models with elongated stretched and variably orientated cells needs to be implemented. For this purpose, a modified Voronoï process in Laguerre geometry will be defined. For the reason that direct modeling of large-scale components based on their real microstructure is extremely extensive and not feasible, the microstructural finite element analysis shall only be used for definition of a probabilistic constitutive law. In its use, the input parameters are the distributions of the most essential properties, the correlation between the properties as well as their spatial correlation. The model will be validated against experimental investigations on coupon and semi-structural level using 4-point-bending experiments. The main advantage of the model to be developed - compared to classical deterministic analyses - is its ability for the reliable and numerically rather efficient prediction of the uncertainty in the structural response of large-scale components since the probabilistic simulations on the micromechanical level are required only for the definition of the probabilistic constitutive law. Thus, a computational method will be available which is able to predict the uncertainties to be expected in large-scale structures based on a stochastic material characterization.

当前提案的目标是开发一种方法，用于在部分由随机微非均质材料（例如固体泡沫）组成的轻质结构中有效地确定和模拟材料的不确定性。这种方法在设计结构和部件时是必需的，因为经典的确定性概念不适用于统计上的微非均质体。出于这个原因，应采用一种概率方法，以具有闭孔泡沫芯的夹层结构为例。该方法将允许在分散的微观结构特性的基础上确定有效材料性能和相应的散射。通过计算机断层扫描可以获得细胞微观结构的大小、形状和方向等必要的输入参数以及相应的概率分布。特别是，应该开发一种方法，考虑微观结构各向异性对有效材料性能的影响。为了发展基于微观结构模拟的概率本构律，需要实现具有细长拉伸和变取向单元的有限元模型的生成算法。为此，将在拉盖尔几何中定义一个修改后的Voronoï过程。由于基于大型构件真实微观结构的直接建模极为广泛且不可行，因此微观结构有限元分析只能用于定义概率本构律。在其使用中，输入参数是最基本属性的分布、属性之间的相关性以及它们之间的空间相关性。该模型将通过4点弯曲实验在板面和半结构水平上的实验研究进行验证。与经典确定性分析相比，待开发模型的主要优势在于它能够可靠且在数值上相当有效地预测大型构件结构响应的不确定性，因为只有在定义概率本构律时才需要微观力学水平上的概率模拟。因此，一种基于随机材料特性的计算方法将能够预测大规模结构中预期的不确定性。