Simulate adhesion between rubber and plastic?

[ptc-5246840]

Hello,

I have received a task of simulating a difficult scenario.

Rubber (Elastollan 1185A) is over moulded over a plastic part (PBT GF20).

The rubber stays on the part due to adhesion between the contact region.

My task is to simulate the situation where the rubber peels off from the plastic part due to pinching force applied on the rubber.

I am unable to comprehend how to simulate this with Simulate 2.0?

Also the available material data for both the materials is limited (from vendor's material sheet): UTS, Poisson's ratio, Breakage Strain, etc.

For both materials I have the stress-strain curves: plastic being elasto-plastic and rubber being hyper-elastic.

I have already created materials in Simulate for the same but dont know how to proceed further?

Also is the co-efficient of friction between the 2 surfaces required? I do not have this...

Any guidance in this activity would be very helpful.

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[danderson · Accepted solution]

Bongir,

From my experience I don't think this is possible within Creo.

Do to the lack of material definition data (adhesive between rubber and part it is bonded to) I have not found a way to do this in Creo Simulate.

You can get some insight into the rubber in how it transfers load but you will need a more advanced solver/software for what you are trying.

Hope this helps,
Don

[ptc-5246840]

Hello Don,

I tried simulating only the rubber part by applying suitable boundary conditions.

I am getting very rough results but it could do with much more refinement if I could somehow vary the displacement on nodes wrt time.

I want that some of the nodes be fixed in XYZ from 0 to 0.5 sec.

For 0.5 to 1 sec the same nodes should be free.

I tried to simulate this by making the displacement a function of time.

But using value 0 for time 0.5 to 1 sec in the graph does not seem to produce any difference.

Is it possible to vary the boundary condition of nodes wrt time for non-linear static analysis?

[mlindqvist]

I would imagine it is possible to use Creo Simulate to calculate the shear / normal stress at the interface between plastic and elastomer. It probably requires some testing to find out what stress combinations that result in failure. Without testing I don't think its possible with any software. When you use FEA in the nonlinear regime, testing becomes more important.

[ptc-5246840]

Hello Mats,

I tried making the contact surface fixed, which implies infinite co-efficient of friction.

This seems to produce rough results.

A better simulation could be obtained if I could enter the shear forces on the contact area instead.

But as you suggested maybe it is not possible to get this value without physical experimentation.

Lets say we decide to physically setup this situation.

The force F at which the rubber gets sepparated from the plastic.

How do I calculate the equivalent shear force for it?

Also what if the load is normal to the plane of contact.

Shear force would not be a good equivalent in that case I think.

[mlindqvist]

From what I understand of your design task, I would typically try a test specimen looking something like this. It should preferably be possible to change the angle alfa in different specimens... I would expect different combinations of shear and normal stress results in failure. Alfa=0 would correspond to pure tension, alfa=90 pure shear. This test setup is not ideal for anges close to 90.

[danderson]

Bongir,

I agree with Mats. Physical testing is needed. From my experience with rubber bonded to alloy parts the only time I have seen the bond fail is due to a processing error this might be different with plastic parts. By design the elastomer or alloy should fail before the bond fails. To get the results that I have needed in the past we have had to go to a software package like ansys or abqus.

Don