短纤维增强镁基复合材料液固态挤压成形中的损伤机理研究

项目名称： 短纤维增强镁基复合材料液固态挤压成形中的损伤机理研究

项目编号： No.51305345

项目类型： 青年科学基金项目

立项/批准年度： 2014

项目学科： 机械、仪表工业

项目作者： 刘健

作者单位： 西安理工大学

项目金额： 23万元

中文摘要： 液固态成形金属基复合材料技术具有变形抗力小、纤维损伤程度小和近净成形等优点。然而，液固态复合材料中液、固相和短纤维三相共存，变形不协调引起的局部应力集中将诱发微裂纹的形核、长大和聚合，最终导致宏观裂纹的产生和材料的失效。本项目以微观损伤行为模拟为切入点，以主动控制微观缺陷为主线，采用数值模拟、工艺试验研究和理论分析相结合的方法，研究变形条件和微观结构对短纤维增强镁基复合材料损伤行为的影响规律。采用随机吸附算法生成基于复合材料微观结构的三维单胞模型，将断裂力学方法引入液固态材料微观损伤模拟中，预测镁基复合材料中由于局部熔化和不协调变形引起的微裂纹的产生；采用基于子模型技术的宏-微观相结合的有限元模拟方法，结合液固态挤压工艺试验和微观缺陷定量分析，最终确立液固态挤压成形过程中复合材料微观缺陷产生的主动控制方法。预期研究成果对液固态成形中的损伤预测和镁基复合材料的实用化具有重要的科学意义。

中文关键词： 镁基复合材料；损伤；液固态挤压；有限元模拟；抗蠕变性能

英文摘要： Plasticity forming of magnesium matrix composites in liquid-solid state has several advantages, such as low deformation resistance, small extent of damage to fiber, and near-net forming. However, solid grain, liquid phase surrounding the grain and reinforcements coexist in the composite, stress concentration induced by the deformation mismatch between the three phases may cause the nucleation,propagation and coalescence of microcracks, which may lead to macro cracks and accelerate the failure of composites. Present study intends to investigate the influence of deformation conditions and microstructure on the damage behavior of the composites by combination of numerical simulation, process experiment，and theoretical analysis, and the goal is to realize the active control of micro defects in liquid-solid forming. A 3-D unit cell model of magnesium matrix composite reinforced by short fiber will be generated based on RSA (Random Sequential Adsorption) method according to the real microstructure. Fracture mechanics method will be introduced to forecast the occurrence of micro cracks due to partial melting and uncoordinated deformation. Macro-micro integrated simulation method based on submodel technique will be adopted to visualize the damage distribution and evolution in the composite. An active control method for

英文关键词： Magnesium matrix composites；Damage；Liquid-solid extrusion；FEM simulation；Creep resistance