results of a FEA on a plastic part
results of a FEA on a plastic part
(OP)
Hi all
I am new to Cosmos so please bare with me.
I have been trying to analyse the darts on a plastic part which is made from acetal resin material. Please see attachment.
The darts are required to deflect 1mm. I always get a factor of safety (FOS) less than 1 to achieve this.
I have tried changing the shape several times.
My understanding, correct me if I am wrong, is that if the FOS is less than one then the part will break. Is this the case? am I missing anything?
Thanks for your help in advance.
I am new to Cosmos so please bare with me.
I have been trying to analyse the darts on a plastic part which is made from acetal resin material. Please see attachment.
The darts are required to deflect 1mm. I always get a factor of safety (FOS) less than 1 to achieve this.
I have tried changing the shape several times.
My understanding, correct me if I am wrong, is that if the FOS is less than one then the part will break. Is this the case? am I missing anything?
Thanks for your help in advance.






RE: results of a FEA on a plastic part
Cheers
Greg Locock
SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: results of a FEA on a plastic part
Rob Stupplebeen
RE: results of a FEA on a plastic part
All i have is a restrained face and a force on the darts. I do not think its the loading. What do you mean by boundary conditions?
I have plotted the stress and it shows that it will be above the yield strength, which is consistent with the FOS. Please see attachment.
I am still worried because from gut feeling (and playing around with other darts) i would assume it shouldn't break.
Any other suggestions of likely mistakes i might have made?
Thanks again.
RE: results of a FEA on a plastic part
What is your yield stress? Is that really 1mm deflection?
Cheers
Greg Locock
SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: results of a FEA on a plastic part
The deflection plot is attached.
Yield Strength is 6.7e7N/m^2 or 67MPa.
Does this mean the darts will break with this deflection?
RE: results of a FEA on a plastic part
Other than that the displacement and stress plots look OK.
Is this dart shorter than your usual design? Is the material stiffer? Does a simple beam calculation agree with your estimated stress?
Cheers
Greg Locock
SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: results of a FEA on a plastic part
Rob Stupplebeen