[FONT=Calibri, sans-serif]I am currently working a stress FEA model (linear analysis) for a 40lbs Air Cart Tank (height of the tank is 5 feet and thickens is 0.3125 inches). The material of this tank [FONT=Calibri, Helvetica, sans-serif]is LLDPE (Linear Low Density Polyethylene). The load applied is [/FONT]hydro static[FONT=Calibri, Helvetica, sans-serif] (fluid fertilizer)[/FONT].
I need to evaluate the stresses and deflections developed in this plastic tank. Upon running the simulation (NASTRAN IN CAD ) I got large displacements (for example, max displacement 10.76 inches).
The Von Misses stresses were much higher than the Yield Strength of this material.
I am wondering if you have any suggestions or comments on what [U][B]failure theory[/B][/U] I could use to determine the stress limits for this LLDPE material.[/FONT]
Best Regards,
Bogdan Chivulescu
Mechanical Engineer
I would use either a mises stress condition, or an effective strain that is dependent on the strain-rate and the stress triaxiality.
-Jorgen