Hi manish,
Attached is the simulation I did with your file, I used the simmetry to simulate only half (with half the load) to be able to see the actual depth of the highly stressed area.
Like we´ve all mentioned anything past yield is not valid with inventor models, what you can get from this simulation is that at 88 tons, the part yields, this yielding is localized though and strain causes steel to harden, the strain hardening problem is much more complex that what Inventors simulation can handle, I would say that this part won´t break under that load but definitely is not safe in the traditional sense of design (yield/SF = maximum stress), sadly there are some areas of engineering that force us to design into the plastic zone, that´s were testing or more complex FEA tools come into play.
As for your concern of the part not breaking under a lot more force that that of the simulation, just look at how much of the material is very well into the safe zone (SF over 5) this coupled with the localized strain hardening of the critical portions mean that the part is a long way off from breaking, but to predict exactly at what load it will break is well outside of Inventor´s simulation capabilities.
BTW: I´ve used FEA to design manhole covers, and there is no way you can design a weight/cost efficient manhole cover that resists the standard (EN 124) required load without allowing some plastic deformation at testing (even the standard allows for some), so maybe your case is similar, you just can´t allow yourself to have a huge safety factor over yield because 1. budget, 2. you´ve done physical testing and you know it holds.
Warning: even though it holds, it doesnt mean it will always hold, over the yield point I´m guessing you have to double-concern yourself if fatigue is involved. In this case we could use a bit more info as to how this works in real life.
Regards,
RM
