【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。更多还原

【Abstract】 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.更多还原