蠕墨铸铁的低周疲劳裂纹扩展速率

Low cycle fatigue crack growth rate of compacted graphite cast iron

为评估高速列车蠕墨铸铁制动盘寿命,开发了钛合金低温(-50℃)整体夹式引伸计和计算机试验数据采集系统,实时同步采集试件缺口张开位移、低周循环次数和载荷位移。采用柔度法通过试件缺口张开位移计算出裂纹长度,以确定疲劳裂纹扩展速率。试验结果表明:所得原板厚试样室温(25℃)与低温(-50℃)低周疲劳裂纹扩展速率曲线趋于一致。在试验温度范围内(-50～25℃)可统一使用室温低周疲劳裂纹扩展速率试验结果。

The life of high speed train compacted graphite cast iron breaking discs was tested using a titanium alloy low temperature -50 ℃ extensometer and crack opening displacement data processing system. The crack opening displacement and the load displacement were measured for low numbers of cycles in real time. The compliance method based on the crack opening displacement parameters was used to calculate the fatigue crack length, and the fatigue crack growth rate. For the original plate thickness, the low cycle fatigue crack growth rate at room temperature 25 ℃ was similar to that at low temperature -50 ℃. Therefore, the room temperature low cycle fatigue crack growth rate test data can be used instead of that of the low temperature -50 ℃ data.