对于各向同性塑性材料，缓慢扩展裂纹尖端的各向异性塑性应力场就变成理想塑性应力场。
For the isotropic plastic material, the anisotropic plastic stress fields at a slowly propagating crack tip become the perfectly plastic stress fields.
疲劳断口上存在典型的疲劳裂纹萌生区、缓慢扩展区、 快速扩展区和最后瞬断区。
The fatigue fractography consists of several different zones, including fatigue crack initiation, slow, fast propagation and final fracture.
BT 20钛合金断裂试验表明，CT试样均在裂纹延性启裂并缓慢扩展后，发生脆性失稳断裂。
Fracture test of the BT20 indicates that brittle unstable fracture occurs after ductile crack initiation and slow propagation for all the compact tension (ct) specimens.
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