韧性材料的高应变率拉伸碎裂过程及材料参数影响  

HIGH STRAIN RATE TENSILE FRAGMENTATION PROCESS OF DUCTILE MATERIALS AND THE EFFECTS OF MATERIAL PARAMETERS

作　　者：郑宇轩[1] 胡时胜[1] 周风华[2] 

机构地区：[1]中国科学技术大学中国科学院材料力学行为和设计重点实验室,合肥230026 [2]宁波大学教育部冲击与安全工程重点实验室,宁波315211

出　　处：《固体力学学报》2012年第4期358-369,共12页Chinese Journal of Solid Mechanics

基　　金：国家自然科学基金(10972108);宁波市科技局配套项目;宁波大学王宽诚幸福基金支持

摘　　要：Grady-Kipp将一个与断裂能量相关的内聚断裂模型引入Mott[1]的刚性卸载波分析,导出一个预测韧性材料在高速拉伸碎裂过程中产生碎片的平均尺度的计算公式[2].为定量评估Grady-Kipp公式的适用程度,采用数值方法模拟了具有不同材料参数的一维弹塑性杆在高应变率拉伸过程中的碎裂现象.通过改变材料的断裂能Gc、密度ρ、屈服应力A和应变率敏感系数C,模拟了杆在不同应变率ε下的碎裂过程,研究了材料参数对碎裂时的碎片尺度、表观断裂应变和断口温升等的影响.通过对应变率和碎片尺寸进行无量纲化,证实Grady-Kipp公式在广泛的材料参数范围内能较好地预测碎裂过程中发生的碎片平均尺寸的下限.By introducing a cohesive fracture model into the Mott[1] momentum diffusion analysis,Grady and Kipp[2] deduced a formula for predicting the average size of the fragments during a ductile fragmentation process.To quantitatively evaluate the accuracy of the Grady-Kipp formula,in this paper,we numerically simulated the fragmentation processes of an elastic-plastic bar undergoing initially uniform high strain rate tensile deformation.The key material parameters,including the fracture energy Gc,the material density ρ,yield stress A and the strain-rate sensitivity C,were varied intentionally for evaluating their effects on the fragmentation process.The average fragment sizes were calculated for a wide range of the prescribed strain rates and the material parameters.It was concluded that the Grady-Kipp model provides reasonably close predictions of the lower limit of the ductile fragment sizes,though slight deviations exist in the cases when the fundamental assumptions in the Grady-Kipp analysis do not apply.

关 键 词：韧性材料 碎裂 碎片尺度 Grady-Kipp公式 Mott卸载波 

分 类 号：O346.1[理学—固体力学]