高匹配焊接接头裂纹的J积分研究

本文研究了含有纵向裂纹或缺陷的高匹配焊接接头材料不均匀性和焊缝宽度对弹塑性断裂表征参量J积分的影响规律.高匹配焊缝被理想化为含有一平行裂纹的一个硬夹层,其屈服应力高于母材.在平面应力条件下利用弹塑性有限元计算得到数值解.研究结果表明,材料不均匀性和焊缝宽度对J积分值有显著影响,特别当名义应力或名义应变较高时影响更大.因此,估算高匹配接头的裂纹推力时必须对此加以考虑.

A J-INTEGRAL ANALYSIS OF CRACKS IN OVERMATCHED WELDED JOINTS

The effects of material inhomogenity and weld width of the over-matched welded joints with a longitudinal crack or flaw upon the J-integral, a charac-terizing parameter for elastoplastic fracture, have been studied. The overmatchedweld is idealized to be a parallelly cracked and sandwiched hard layer, the yieldstress of which is higher than that of the base metal. Numerical solutions were ob-tained by using elastoplastic finite element method under the assumption of plane stress.The results show that the values of J-integral are remarkably affected by the mate-rial inhomogenity and the weld width especially when the nominal stress or nominalstrain is comparatively high, which, therefore, should be taken into account whenevaluating the crack driving force for a overmatched joint.