MECHANICAL MODELING OF INHOMOGENEOUS MEDIA AND APPLICATION TO EVALUATION OF HEAT AFFECTED ZONE IN WELD JOINT STRUCTURE

非均匀介质力学建模及其在焊缝结构热影响区评估中的应用

• 批准号: 11650089
• 负责人: IMATANI Shoji
• 金额: $ 2.05万
• 依托单位: KYOTO UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1999
• 资助国家: 日本
• 起止时间: 1999 至 2000
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11650089/
• 关键词: Inhomogeneity; Heat Affected Zone; Crystal Plasticity; Finite Element Method; Microscopic Deformation; Material Anisotropy; 有限変形理論; 成形限界

In order to establish the analytical methodology to evaluate the mechanical behavior of inhomogeneous materials, microscopic deformation is investigated on a heat affected zone (HAZ) of weld joint material. The following results are obtained.1. Hradeness of heat affected zone In the heat affected zone of Mod.9Cr-1Mo steel, we observe fine grain region and coarse grain region. It is found that the hardness of fine grain region is lower than the other, which is completely opposite to the well-known Hall-Petch effect. This is caused by the complicated temperature history in the course of generation of HAZ.It is still necessary to measure the deformation in more microscopic level of several grain size order.2. Model analysis of polycrystalline material Introducing a crystal plasticity model by Asaro and Needleman into three-dimensional finite element method, a polycrystal model is proposed. As a result of analysis, it is shown that more variety in strain is predicted in larger grain size region. Such a tendency shows qualitative agreement with experiment.3. Evaluation of grain sliding By use of a joint element technique across the brick elements, sliding in grain boundary is predicted. And the sliding in grain boundary accelerates the variety in strain. This technique is applicable to the deformation analysis at high temperature, in which the slide causes small crack opening.4. Modeling of self-adaptation in terms of anisotropy A constitutive model taking account of the variation of anisotropy is proposed. The anisotropy changes its direction due to the surrounding circumstances. It is shown that the model is applicable not only to the fiber-reinforced materials but also to other materials such as biological tissues, in which self-organization takes place while changing inhomogeneity by themselves.

为了建立评价非均匀材料力学行为的分析方法，对焊接接头材料的热影响区进行了微观变形研究。得到了以下结果：在mo . 9cr - 1mo钢的热影响区，我们观察到细晶粒区和粗晶粒区。研究发现，细晶区硬度低于其他区域，这与众所周知的Hall-Petch效应完全相反。这是由于热影响区产生过程中复杂的温度历史造成的。在更微观的几个晶粒级的形变测量中仍有必要。将Asaro和Needleman的晶体塑性模型引入三维有限元方法，提出了一种多晶材料模型。分析结果表明，在晶粒尺寸较大的区域，应变变化较大。这种趋势与实验结果在定性上是一致的。利用砌块间的节理单元技术，对晶界滑动进行了预测。晶界的滑动加速了应变的变化。该方法适用于滑动引起小裂纹张开的高温变形分析。提出了一种考虑各向异性变化的本构模型。各向异性会因周围环境而改变方向。结果表明，该模型不仅适用于纤维增强材料，也适用于其他材料，如生物组织，它们在自我改变非均质性的同时发生自组织。

项目成果

Ryohei MAEDA: "Microscopic Deformation of Heat Affected Zone in Weld Joint and Crystal Plasticity Analysis (in Japanese)"Proceedings of 50-th Annual Meeting of The Society of materials Science Japan. (to appear). (2001)

Ryohei MAEDA：“焊接接头热影响区的微观变形和晶体塑性分析（日文）”日本材料学会第 50 届年会论文集。

Shoji IMATANI: "A Constitutive Model of Adaptation and Anisotropy for Growing Material"Material Science Research International : Special Technical Publication-2. (in print). (2001)

Shoji Imatani：“生长材料的适应和各向异性的本构模型”国际材料科学研究：特别技术出版物-2。

Shoji IMATANI: "A Constitutive Model of Adaptation and Anisotropy for Growing Material"Material Science Research International : Special Technical Publication-2. (発表予定). (2001)

Shoji Imatani：“生长材料的适应和各向异性的本构模型”国际材料科学研究：特别技术出版物-2（即将出版）。

Shoji IMATANI: "Finite Element Analysis of Growing Processes Based on a Self-adaptation Model"Proceedings of The fifth International Seminar on Microstructures and Mechanical Properties of New Engineering Materials. (発表予定). (2001)

Shoji Imatani：“基于自适应模型的生长过程的有限元分析”第五届国际新型工程材料微观结构和机械性能研讨会论文集（即将发表）。

Shoji IMATANI: "Finite Element Analysis of Growing Processes Based on a Self-adaptation Model"Proceedings of The fifth International Seminar on Microstructures and Mechanical Properties of New Engineering Materials. (to appear). (2001)

Shoji Imatani：“基于自适应模型的生长过程的有限元分析”第五届国际新型工程材料微观结构与力学性能研讨会论文集。