leometwu的部落格

疲勞破斷面 欣賞

  
 

下: a/c 為疲勞破裂前進過程的緩裂區(就是疲勞破裂區). b 為最後的驟裂區(過載區).  兩個緩裂區代表双向受力. 兩個緩裂區面積差異很大, 代表其双向受力嚴重不均.

Fatigue life is  dirrectly  proportional to its surface tensile strength. This fatigue crack occurred because its surface strength is not high enough. Induction case hardening might solve the problem.

Below: Big difference between area a & c indicates that the stresses on both directions are very different in their magnitudes. This might be caused by improper set-up of the testing equipment.

Below: multi  crack origins indicated by arrows.

Beach marks 間距越來越大是因為裂口越來越大, 每次剩下未裂開的面積越來越小, 其所承受的應力也就 越來越大 , 所以裂口鋒面(crack front)每次前進的距離 就越來越大.

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