yeild strength for ABS

Young's modulus / 43 ... it's my bydefault value!

"Lee Bazalgette" a écrit dans le message de news:40f300a6$1 snipped-for-privacy@mk-nntp-1.news.uk.worldonline.com...

Lee,

The critical question is, what are you trying to model? If you are designing a one-time snap and it doesn't matter if the part yields slightly you will use a different value than if you are designing a part that is expected to flex thousands of times. Is it a momentary stress or is it a constant load on a part expected to be in service for 10 years? Is it an impact load? Is the part stressed at room temperature or at some high or low temperature? Is it a tensile stress, a compressive stress, a flexural stress? How is the part manufactured? If it is injection molded, is there a knit line in a highly stressed area? Which grade of ABS? What are the consequences of a failure? The answers to the above question would probably change the value I would use for my failure criteria by a factor of 10 or more.

Jerry Steiger Tripod Data Systems "take the garbage out, dear"

Cosmos Xpress is pretty weak at analyzing plastics. The assumptions that it uses are:

1. Linear elastic behavior. This means it has the same modulus regardless of strain.

1. Isotropic. This means it has the same properties in every direction.

2. Not viscoelastic. It doesn't flow and gets its stress strain properties from elasticitiy not entropy.

1. Not temperature dependent.

Plastics don't really meet these criteria except under a very narrow range of circumstances.

In addition to some kind of modulus or stress strain curve you would need the poisson's ratio for ABS.

in article 40f300a6$1 snipped-for-privacy@mk-nntp-1.news.uk.worldonline.com, Lee Bazalgette at snipped-for-privacy@REMOVEbazal.freeserve.co.uk wrote on 12/7/04 10:20 pm: