| 邹广平*,唱忠良,曲嘉,陈思,王瑞瑞.平面应变下紧凑拉伸试样的动态断裂韧性的实验研究[J].实验力学,2011,26(3):240~246 |
| 平面应变下紧凑拉伸试样的动态断裂韧性的实验研究 |
| Experimental Study of Dynamic Fracture Toughness of Specimen Subjected to Compact Tension under Plane Strain |
| 投稿时间：2010-11-05 修订日期：2011-01-05 |
| DOI： |
| 中文关键词: 紧凑拉伸试样 动态应力强度因子 动态起裂韧性 平面应变 |
| 英文关键词:compact tension specimen dynamic stress intensity factor dynamic fracture toughness plane strain |
| 基金项目:教育部博士点基金(No. 20092304110003)资助 |
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| 中文摘要: |
| 材料的动态断裂韧性是衡量材料在动载荷作用下抵抗裂纹扩展能力的重要指标，以往的材料动态断裂韧性测试多采用三点弯曲试样，而针对紧凑拉伸试样的动态断裂韧性研究很少。本文将紧凑拉伸试样(即CT试样)简化成等效弹簧质量模型，得到了CT试样动态应力强度因子的近似表达式。对Hopkinson压杆装置进行了改进，利用改进后的实验装置进行了CT试样的平面应变型动态断裂实验。由于载荷在起裂前(以至起裂后一段时间)是单调增加的，因此可以用动态应力强度因子K(t)作为裂纹尖端的表征参量，并用动态冲击载荷（或加载点位移）曲线来确定动态应力强度因子K(t)；利用电阻应变片法确定起裂点，最终获得了表征材料动态起裂韧性的KId。由此形成一整套平面应变型动态起裂韧性的表征和测试方法。同时利用该方法对2A12铝合金和16Mn合金钢的CT试样进行了断裂韧性测试，从实验结果可以看出改进后的装置和测试方法是可靠而有效的。 |
| 英文摘要: |
| Dynamic fracture toughness of material is a importan index evaluating material's crack growth resistance under dynamic load. In the past, most dynamic fracture toughness measurement was based on three-point bending specimen, and the dynamic fracture toughness study of compact tension (CT) specimen was rarely carried out. In this paper, CT specimen is simplified as an equivalent spring-mass model, then an approximate expression of dynamic stress intensity factor of CT specimen is obtained. The existent Hopkinson pressure bar equipment was improved first, then elastic-plastic dynamic fracture experiments under plane-strain state of CT specimen were carried out by using the improved equipment. The dynamic stress intensity factor K(t) is used as a token parameter of fracture top, and the dynamic stress intensity factor K(t) is determined by dynamic impact loading curve (or the displacement of loading point), since the load is monotonically increased before crack propagation and even during a period of time after fracture formation. The resistance strain gage method was used to determine the crack initiation. Finally, the dynamic fracture toughness KId of the typical specimen was obtained. Results indicate that the token and the testing method of dynamic fracture toughness are feasible in dynamic fracture mechanics. Above method was adopted to test the CT specimen fracture toughness of 2A12 aluminum alloy and 16Mn steel, respectively. Experimental esults show that the improved device and testing method is reliable and effective. |
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