高应变率下Cu-P/M摩擦材料正向和反向应变率效应  

Positive and Negative Strain-Rate Effect for Cu-P/M Friction Materials at High Strain Rates

作　　者：刘建秀[1,2] 高红霞[1] 韩长生[3] 魏秀兰[1] 

机构地区：[1]郑州轻工业学院 [2]中国工程物理研究院流体物理所,绵阳621900 [3]中国工程物理研究院流体物理所

出　　处：《机械科学与技术》2005年第2期230-232,247,共4页Mechanical Science and Technology for Aerospace Engineering

基　　金：中国工程物理研究院基金(421010201);河南省杰出青年基金;河南省重点攻关项目(03230239000)资助

摘　　要：研究了冲击载荷下铜基粉末冶金(Cu P/M)摩擦材料不同的应变率效应。试验在分离式Hopkinson压杆 (SHPB)上完成。应变率范围为:102/s～103/s。通过试验得到了该材料的动态应力应变曲线,发现该材料在应变率 1000/s以下,表现为应变率强化效应;在应变率1000/s以上,表现为应变率弱化效应。也就是说,应变率1000/s是 该材料的临界应变率。为了与静态时的情况比较,在MTS试验机上又做了10-4/s～10-3/s应变率范围内的准静态 实验。比较动静态试验结果,发现动态时的屈服极限大于静态的;而屈服后的应变硬化率是静态大于动态的。通过 对样品进行微观组织分析,发现在压制烧结时有硬质颗粒破碎。在冲击载荷下材料内部的损伤演化形成大范围的 多源裂纹及孔洞分布群导致裂纹迅速扩展,同时伴随硬质颗粒破碎。The dynamic behavior of this material under impact loading was investigated. Quasi-static tests at strain rates of 10 -4 /s^10 -3 /s were performed before the dynamic tests in order to make a comparison. The elastic moduli and yield strain hardening rate were measured. The static curves show the strain-hardening effect. Impact tests were conducted on Hopkinson pressure bar at strain rates of 10 2 /s^10 3 /s. Specimen size is 12 mm×6 mm, strain rate and hardening effect was observed at rates under 1000/s, whereas weakening effect was seen at higher rates, which means that 1000/s is the critical impact strain rate. It is shown from microscopic analysis that sliding shear failure occurred at strain rate of 1600/s, and there are a huge number of paralleling sliding cracks on the surface that induced material failure. The plastic deformation was dominated by sliding with a small amount of twinning. The damage of hard particles was observed.

关 键 词：粉末冶金 摩擦材料 分离式HOPKINSON压杆 冲击 应变率效应 损伤 

分 类 号：TF12[冶金工程—粉末冶金]