elastomer modulus

[Tmssankar]

Dear Dr.Jorgen

like lindemann hardness shoreA and Young's modulus

any analytical relation between temperature modulus and viscosity
thanks in advance
with regards
tmssankar

[Jorgen]

Hmm, there certainly is a relation between the temperature dependent modulus and the viscosity. Perhaps you can try the WLF equation, or your own heuristic relation.

-Jorgen

[Tmssankar]

Dear dr.jorgen
i have done stress relaxation experiment for 2 times.
First 3 hrs 80% strain and 10mm/min as strain rate it shows decay of 24% in 3 hours

second i done 7 hrs 40% strain and 2mm/min as strain rate it shows decay of 28% in 7 hours and 24% in 3 hours.

I reffered that rate of relaxation depends on strain rate.
Is filler ratio and curring time affects rate of decay?
Material is fluoro carbon of shore a70.

Please tell me a correct strain rate andstrain. I have t o get less than 20% of decay in 3 hours.

I am waiting for ur reply

[Jorgen]

Yes, both the volume fraction of filler and the curing can effect the stress relaxation behavior.

Are you trying to design a material that has a desired amount of relaxation, or are you trying to obtain a model that predicts a 20% decay in 3 hours?

-Jorgen

[Tmssankar]

ok thank you jorgen.
i am doing the project elastomer gasket life prediction using FEA for my M.Tech Thesis.
i have bought material from market. to evaluate material properties i have done stress relaxation experiment in uniaxial tension mode of loading.

with 40% initial strain and 2mm/min cross head speed for 7 hrs it shows 28% degradation.
i am using abaqus. the life time is depends on tau. it depends on good fit of test data with prony curve and also minimum % of stress decay.
for the 7 hrs first 2 hrs it shows 20% decay only it gives more value of tau near to 2E7mins. for 3 hrs it shows 22% decay. if i fit datas for 3 hrs means it gives 32000min as tau. what i follow?

any experimental parameter like strain rate or other how affects relaxation?
what strain rate and initial strain i have to apply?

[Jorgen]

You are using a Prony series with multiple tau ang g values, right?
Have you tried to add more terms to your Prony series?

-Jorgen