4C2 Tripos 2013

Question 1

What is the equation for the moment in terms of the bending moment per unit length used in the laminate plate theory matrix Mx, My, Mxy?

Answer 1

M = Mx*b

b- width of the section

Question 2

What is the Tsai-Hill failure criterion for composite materials?

Answer 2

The Tsai-Hill failure criterion (the formula for which is given in the Data Sheet) is a basis for prediction of whether a unidirectional composite ply will fail under a given stress state, expressed as normal stresses parallel and transverse to the fibre axis, and the shear stress parallel to the fibre axis, given the critical stresses for these three modes of failure. It effectively takes account of interactions between these modes, particularly transverse tension and shear parallel to the fibre axis, whereas the maximum stress criterion only considers each failure mode in isolation.

Question 3

What is the first step when interpreting loading conditions for a constraint study?

Answer 3

Convert the loading into stress resultants

Question 4

When calculating the thickness of a laminate using constraints, what is an important step to realise?

Answer 4

That not all ply directions will contribute to the stiffness against a given constraint, so the thickness value calculated will only be for the plies contributing ie. 0 degree direction for tension and bending, and 45 degree direction for shear