In a short beam shear testing of polymers, the configuration is such that the top (loading) roller is bigger than the bottom (support) rollers. Why is this the case, and what happens when the size of both top and bottom rollers is the same?
1 Answer
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To make sure the failure is not a flexural failure, involving a bending moment.
A wide roller on top encourages distributing maximum bending over a larger area, reducing maximum moment.
Also, it encourages the shear at supports, optimized for interlaminar shear stress, in case they are interested in that.
