定向有机玻璃疲劳断裂性能的频闪法研究

疲劳裂纹扩展前应力集中区域变形场的测试对材料疲劳性能的研究起到至关重要的作用。但由于疲劳试验为动态的过程,在动态下测量比在静态下要复杂得多,这样就给变形场的测量带来了困难。通过调节频闪光源的频率使其与疲劳试验机的频率相同,可把此动态过程转换为准静态过程,采集不同循环周期内的相同时刻的灰度图像,并运用数字图像频域相关分析法进行测试。本文运用此方法对定向有机玻璃缺口应力集中区域的变形场进行了测试,并分析得出其层间疲劳断裂力学性能薄弱的结论。

On the Fatigue Fracture Properties of Directional PMMA Based on Stroboscopic Method

The deformation testing in stress concentration area before fatigue crack propagation plays a crucial role for understanding the fatigue properties of materials. However, fatigue testing is more complex due to its dynamic process, so it makes the deformation measuring quite difficult. By adjusting the frequency of stroboscopic light source consistent with fatigue tester, the original dynamic process of fatigue testing may be transformed into a quasi static one. Digital image correlation method in frequency domain was used to measure the deformation by gray images recorded an the same moment but in different cycle periods. This method was used to measure the deformation in the stress concentration area (round a notch) for directional PMMA material. Results show that the interlamination fatigue strength of directional PMMA material is weak.