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一、引言J积分和裂纹顶端张开位移δ往弹塑性断裂力学里居很重要的地位。人们假定J=J_c或δ=δ_c是裂纹开始扩展的判据,并试图在J_c与δ_c间互相换算。因此,研究J与δ之间的关系是个有价值的课题。目前,常被引用的关系呈J=βσ_yδ(1)的形式。例如:应用无硬化的塑性区窄条模型得到β=1。J=σ_yδ经常被用来做计算。但是,无硬化不符合金属的实际。我们的实验数据表明即使对于σ_(0.2)≈100公斤/毫米~2级高韧性钢(J_(Ⅰc)≈12公斤/毫米)J=σ_yδ所给出的δ已经偏大,对于中、低强度钢
I. INTRODUCTION The J-integral and crack tip open displacement δ are very important to elasto-plastic fracture mechanics. It is assumed that J = J_c or δ = δ_c is the criterion for crack initiation and attempts to convert between J_c and δ_c. Therefore, studying the relationship between J and δ is a valuable topic. At present, the frequently quoted relation is in the form of J = βσ_yδ (1). For example: Using a plastic zone-less strip model yields β = 1. J = σ_y δ is often used to make calculations. However, no hardening does not conform to the actual metal. Our experimental data show that δ is large even for J = σ_yδ for σ_ (0.2) ≈100 kg / mm 2 high toughness steels (J_ (Ic) ≈12 kg / mm) steel