动态裂纹扩展韧性 K_(ID) 的估算及方法的评估

通过对30CrMnSi2A钢制成的DCB（带裂尖小孔）试件的试验结果和利用动态有限元法（DFEM）与远场路径无关的J′积分相结合的方法计算了动态裂纹扩展韧性。较全面地对各种估算KID的工程方法进行了分析比较和评估，讨论了使用范围。此外，改进了Kanninen的半经验公式，使它能对于不同泊松比的材料能方便地估算极限速度VL.同时，指出材料常数m应与裂纹的初始长度和止裂长度aa及裂尖半径有关，给出了计算公式，使得估算KID更为简便和合理。

ESTIMATION AND ANALYSIS OF THE DYNAMIC CRACK PROPAGATION TOUGHNESS

Using the Double Cantilever Beam (DCB) specimen made by 30CrMnSi2A and dynamic finite element method (DFEM) combined with the J′ integral independent of far field path, the dynamic crack propagation toughness KID is calculated. An estimation and analysis of different engineering methods for estimating KID are carried out. The empirical Kanninen′s formula is improved to predict the limiting speed VL easily for different Poisson ratios of materials. Meanwhile, it is shown that the material constant m is dependent on initiation and arrest length of the crack and associated with the radius of the crack tip. A formula for predicting m is given.