Cyclic plasticity for fatigue evaluation

[gurmeet2003]

I have an application for fatigue evaluation where the stress goes above yield. I have briefly surveyed the literature both FEA and fatigue. It appears that I need to specify cyclic stress-strain properties. The materials are AISI 4140 (UTS 150000 psi) and steel UTS 80000 psi. If any one could throw some light on these material properties and where I can get them I will be highly obliged.

Thanks,

Gurmeet

 

[gfbotha]

I am no expert on this, but once used theory and typical material values from the following 2 sources:

1. Mech. Eng. Design (Shigley)
2. Mech. Eng.'s Handbook (Kutz)

Both offers Manson's equation and some typical material properties re-printed from ASTM sources (you might want to follow this up). Nearest to what you want, listed by them, seems to be 4142 or 4340 with typical cyclic (lower) yield strength and the cyclic strain-hardening exponents being mentioned. Say, Sy=65% and n=0.14 ?

A further problem is that cycling rate (generating heating) also has an influence...

Gert

 

[rb1957]

please don't double thread ... see your other thread for my comments

 

[gurmeet2003]

rb1957,

I thought the topic is of interest to different forums. That is the reason for cross posting. I have read your reply in the other forum and appreciate it.

Thanks,

Gurmeet