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An adaptive FE²-model for the analysis of the non-linear, thermo-mechanically coupled behavior of fiber-matrix composites

用于分析纤维基复合材料的非线性热机械耦合行为的自适应 FE² 模型

基本信息

批准号：
283581644
负责人：
Professor Dr.-Ing. Sven Klinkel
金额：
--
依托单位：
Lehrstuhl für Baustatik und Baudynamik
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2015
资助国家：
德国
起止时间：
2014-12-31 至 2019-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/283581644?language=en
关键词：
adaptive FE model analysis non

项目摘要

The analysis of structures with a heterogeneous microstructure, e.g. fiber reinforced concrete or metal composites, requires knowledge of the averaged, effective material parameters. Effective material parameters for heterogeneous composites can be estimated by homogenization processes. The (Finite Element)²- /FE²-method allows for a simultaneous numerical homogenization during the calculation of the overall structure. Therefore, a representative volume element is attached to each integration point of the overall structure. It captures the nonlinear material behavior and provides information on micromechanical processes. The disadvantage of the FE²-method is the high computational cost. It necessitates a finite element analysis of the microstructure in each integration point. Hence, the definition of the finite element model is required for the numerical homogenization to calculate the effective material parameters for each integration point of the overall structure. The research project aims for reducing the computational effort. For this reason, an adaptive FE²-model shall be developed. The coupled numerical homogenization should only be performed in regions where nonlinear material behavior is expected. The adaptive numerical homogenization method is developed for fiber-matrix composites. Here, shape memory alloy (SMA) fibers are considered as fiber reinforcement. Due to the shape memory effect these fibers are able to prestress the cement based matrix materials. The stress-strain-behavior of SMA is strongly nonlinear and depends on the surrounding temperature. If the temperature is known, the nonlinear material behavior is observed, when the stress is increased beyond a characteristic stress value. The material behavior is linear below this stress. Some matrix materials behave similarly; they show linear behavior as long as the stress is below a characteristic value. If the overall material response is linear, an initial homogenization will lead to the effective material data; a simultaneously performed numerical homogenization is not necessary. The research project aims for the development of an indicator which is able to estimate the regions with linear and nonlinear material behavior of the fiber-matrix-composite. This criterion should be valid for possible nonlinearities of the matrix and the fibers. The change of the material behavior for different temperatures and different fiber orientations needs to be considered. The indicator has to be extended for varying temperatures. For the determination of the temperature the non-steady-state heat problem is solved. The effective heat conductivity of the heterogeneous material is derived by a numerical homogenization as well. The indicator allows for a local application of the FE²-method. The project aims for the development of a simulation tool to analyze SMA-fiber-matrix composites, which accounts also for the ability to prestress matrix materials.

分析具有非均质微结构的结构，如纤维增强混凝土或金属复合材料，需要了解平均有效材料参数。非均质复合材料的有效材料参数可以通过均匀化过程来估计。有限元/有限元方法允许在整体结构的计算过程中同时进行数值均化。因此，在整体结构的每个集成点上都附着有代表性的体积元素。它捕捉材料的非线性行为，并提供有关微机械过程的信息。有限元方法的缺点是计算量大。这就需要对各结合点的微观结构进行有限元分析。因此，需要定义有限元模型，以便进行数值均匀化，以计算整体结构每个整合点的有效材料参数。该研究项目旨在减少计算工作量。为此，应开发自适应有限元模型。耦合的数值均匀化应该只在期望非线性材料行为的区域执行。提出了适用于纤维基复合材料的自适应数值均匀化方法。这里，形状记忆合金纤维被认为是纤维增强材料。由于形状记忆效应，这些纤维能够对水泥基材料施加预应力。形状记忆合金的应力-应变-行为是强非线性的，并且依赖于环境温度。如果温度已知，当应力增加到超过特征应力值时，可以观察到材料的非线性行为。在此应力下，材料行为是线性的。一些基质材料的行为类似；只要应力低于特征值，它们就显示出线性行为。如果总的材料响应是线性的，则初始均匀化将导致有效的材料数据；同时执行的数值均匀化是不必要的。本研究项目旨在开发一种能够估计纤维基复合材料的线性和非线性材料行为区域的指示器。该判据对于基质和纤维可能存在的非线性是有效的。需要考虑材料在不同温度和不同纤维取向下的行为变化。指示器必须延长以适应不同的温度。对于温度的确定，解决了非稳态热问题。通过数值均匀化，得到了非均质材料的有效导热系数。该指示器允许在本地应用有限元分析方法。该项目旨在开发一种分析SMA纤维基复合材料的模拟工具，该工具还考虑了对基质材料施加预应力的能力。