Solving for "Delta L" -L

[reamer]

I have a piece of cured 2 part Thermoset #104 material that has a tensile capacity of 2,850 psi. It measures .5 x.5x1.4" I want to know how many pounds of force I can load it with. The load would be placed in the center of the 1.4" length at .7". A piece of steel will be placed on top of it. It will be laying the bolster plate of my hydraulic press when I push on it. To find stress, load is divided by surface area. To find strain, ÄL divided by L. where L is the thicknes ie, .5" in this case and ÄL is the amount of expected deformation of the Thermoset due to the force applied. How would you know what percentage of deformation will take place if you haven't pressed on the piece yet? Is this where the factors for modulas of elasticity comes in? Is "ÄL" the modulas of elasticity factor? Modulas of elasticity of cured 2 part epoxy Thermoset #104 is posted as between .2 and .4.