Determining the Force Needed to Deform a Silicone Gasket by 0.5mm?

[Mech King]

Hi guys,

i am having a bit of difficulty with the following problem:

I have an arrangement whereby i have a silicone seal washer lying on a flat surface. A circular hollow tube is mated on top of the the washer/gasket which will from a seal once the tube is secured in place with a certain amount of preload. To be honest the amount of preload is not important to me as the seal is not critical.

If i want the washer to deform say 0.5mm and it's 2mm thick, how do i determine the load required to deform the washer by this amount, and can it even be compressed this much?

I have tried calculating simple Strain due to compressing the washer by 0.5mm and then i have multiplied this value by the Modulus of Elasticity in order to determine the stress. I then wanted to use this value to determine the force due to the contact area of the circular tube, but because the value for The Elastic modulus is about 150 GPa, the resulting force seems somewhat unrealistic.

I am using some plastic snap features to hold the tube in place, and i wanted to determine the max tensile load they would see as a result of the compression of the washer before snapping into there retaining feature.

Would anyone please be able to help clarify my thinking above; if I'm on the right lines or if i need to go about it another way? Any help would be much appreciated.

There is surprisingly little info on this on the net :(

Best regards to you all

mech King

 

[Navin A S]

.The best way to approach this problem is to use the concept of Young's Modulus. Young's Modulus is a measure of the stiffness of a material and is expressed as stress (force per unit area) over strain (deformation per unit length). You can calculate the force required to deform the washer by 0.5mm using the following equation: Force = (Young's Modulus * Area of Washer) / Deformation Where Area of Washer is the cross-sectional area of the washer, and Deformation is the amount of deformation (0.5mm in this case). This will give you the total force required to deform the washer by 0.5mm. You can then use this force to calculate the maximum tensile load that your plastic snap features would see by dividing the total force by the number of snaps used. I hope this helps!