离散元法论文压敏陶瓷材料压制过程的离散元模拟和实验.doc

离散元法论文：压敏陶瓷材料压制过程的离散元模拟和实验研究【中文摘要】压敏陶瓷材料作为一种应用广泛的功能陶瓷,在人们的日常生活中起着非常重要的作用。压敏陶瓷材料性能的优劣不仅受材料本身的影响,而且受成型工艺条件的影响,由于成型工艺条件变化因素较多,采用实验的方法来进行工艺优化研究需要消耗大量的资源。本文提出使用数值模拟的办法来进行压敏陶瓷材料成型的研究,进行了不同工艺条件下压敏陶瓷粉体材料成型过程的离散元模拟以及实验研究,讨论了成型工艺对成型后坯体力学性能的影响因素,为成型实验提供一定的理论依据。本文各章节的主要研究工作如下:第一章总结了压敏陶瓷材料的特点及应用,阐述了陶瓷成型技术以及机理。通过文献调研,讨论了国内外关于陶瓷粉体材料成型工艺研究现状,以及使用模拟的方法进行成型的研究现状。提出使用离散元法来进行粉体材料成型的研究的优点,以及本文的研究意义;第二章介绍了离散元法的发展及相关理论,选择了适合于陶瓷粉体材料成型研究的离散元模型。介绍了基于离散元法的PFC软件相关理论,以及它的计算方法和假设;第三章引入相似性原理,建立起基于相似性原理的离散元模型,得到模型与原型之间参数的比值关系。对所建立的离散元模型进行参数的校核,详细的介绍了校核的方法和过程,最后得到ZnO和Bi2O3微观参数;第四章研究了不同的压制环境、压制方式以及不同尺寸模具情况下,压敏陶瓷材料成型的离散元模拟与实验研究。探讨了重力对成型后坯体的力学性能的影响,从机理上分析重力与微重力环境中成型坯体力学性能不同的因素,同时结合重力环境中的成型实验,验证模拟的正确性;单双向加压情况下,成型坯体的力学性能不同,从微观的情况下分析产生这种差别的原因,使用实验的方法进行单双向加压成型,得到压敏陶瓷片的压敏性能不同;选用不同尺寸的模具进行模压成型的模拟,得到成型坯体的力学性能有较大差别,分析了导致这种现象产生的原因。最后,对本文的研究工作进行了总结与展望。【英文摘要】As a kind of widely used functional ceramic, pressure-sensitive ceramic material plays a very important role in peoples daily life. The main research work in this paper are following :The performances of the pressure-sensitive ceramic material are not only affected by the material itself, but by the different molding process conditions. While the effects of ceramic powder material molding process conditions are very volatile, using the experimental method to optimize the compaction conditions will consume large amounts of resources. In this paper, the compaction process of ceramic materials was investigated, the discrete element method (DEM) simulation and experiment process of the compaction process of ceramic material under different compaction conditions were carried out, the compaction technologys affect on the physical performance of the molded green-body was discussed. And it is hoped that the research in this paper can provide some theoretical basis for compaction experiment.The main research work in this paper are following :In the first chapter, the characteristics and application of pressure-sensitive ceramic material was presented, as well as the forming technology and mechanism of ceramics material was expounded. The research status quo of ceramic powder material compaction were discussed both at home and abroad through the literature investigation, together with status quo about using simulation methods on ceramic compaction research. The advantage of using discrete element method to research the compaction process of powder material and the significance of this paper were proposed;In the second chapter, the development and theory related to discrete element method was presented, and a suitable discrete element model suited for the ceramic powder materials was choose. The theory of PFC software based on discrete element method as well as its calculation method and assumptions was introduced;In the third chapter the similarity principle and the reasons for importing the similarity theory for the discrete element method model in this paper was introduced. The discrete element model based on the similarity theory was set up, and the parameters relationships between the model and prototype were obtained. The parameters of discrete element method model were adjusted, the adjust method and the process were detailed introduced, finally the micro parameters of ZnO and Bi2O3 were obtained; In the fourth chapter discrete element method simulation and experimental investigation on the compaction process of pressure-sensitive ceramics materials under the different compaction environments, compaction patterns and different sizes of the molds were researched. The affection of gravity on the mechanical property of molded green-body, From the mechanism analyzed the different factors of modeled green-body under the gravity and micro-gravity environments, meanwhile, in combination with the compaction experiment under the gravity environment to verify the correctness of the simulation process were discussed; On the conditions of single-axial compression and two-axial compression, the mechanical properties of the modeled green-body were different, the reasons for the differences from the case of microscopic were analyzed; through the method of experiment modeled compaction process of the ceramic powder by single-axial and two-axial patterns, different pressure-sensitive performances of the ceramic wafers were presented; the mechanical properties of the modeled green-body were different by choosing different size moulds to simulate the compaction process, the reasons of this phenomenon were analyzed.Finally, summarization and prospect were presented in this paper.【关键词】离散元法 压制成型 相似性原理 应力分布 孔隙率【英文关键词】Discrete Element Method compression molding similarity principle stress distribution porosity【目录】压敏陶瓷材料压制过程的离散元模拟和实验研究摘要4-5Abstract5-6物理量名称及符号9-11第1章 绪论11-161.1 课题背景及研究意义111.2 压敏陶瓷材料的主要用途和基本性质11-121.3 陶瓷压制成型工艺12-151.3.1 陶瓷材料压制方法121.3.2 陶瓷材料压制机理12-131.3.3 陶瓷材料压制成型工艺的国内外研究现状131.3.4 粉体压制成型工艺计算机模拟的国内外研究现状13-151.4 本文主要研究内容和意义15-16第2章 离散元法及粉体材料的离散元模型16-272.1 离散元法简介16-222.1.1 离散单元法的基本理论16-172.1.2 离散元力学模型以及基本定律17-222.1.3 离散单元法计算循环222.2 颗粒离散元法及PFC2D/PFC3D 软件22-242.2.1 PFC2D/3D 软件232.2.2 FC2D/PFC3D 的基本假设和接触本构关系23-242.3 粉体材料的离散元模型24-262.3.1 线弹性模型的基本假设252.3.2 线弹性模型的参数和性能25-262.4 本章小结26-27第3章 基于相似性原理的粉体材料离散元模型的建立27-473.1 结构缩尺模型的相似性原理27-303.1.1 相似的概念及相似比273.1.2 相似理论基本定理及体系27-293.1.3 相似准则的导出方法29-303.1.4 相似性原理在本缩尺模型中的应用303.2 基于相似准则材料参数的校核30-463.2.1 模型参数校核的方法和过程34-363.2.2 参数校核过程中使用的实验仪器及实验过程36-373.2.3 Bi_2O_3 粉体材料离散元模型参数的校核37-423.2.4 ZnO 粉体材料离散元模型参数的校核42-463.3 本章小结46-47第4章 几种工艺条件下压敏陶瓷材料压制成型的研究47-644.1 不同环境条件对压敏材料压制成型影响的研究47-534.1.1 微重力环境下压敏材料压制成型过程的离散元模拟47-494.1.2 重力环境下压敏材料压制成型过程的离散元模拟49-514.1.3 重力环境下压敏材料压制成型实验51-524.1.4 重力对粉体材料成型过程影响机理分析52-534.2 加压方式对压敏材料压制成型