Problem 3 (20 pts):

A unidirectional lamina is subject to a bi-axial stress state as shown in the following figure.

The fiber directional is oriented 0-30° to the loading direction x. The stress ay is proportional

to ox by a factor of B (B is a positive number). Assuming ox is always positive (meaning tensile

stress). Using maximum stress criterion, please discuss the possible change of failure mode by

varying the proportional factor B. Determine the range of ß for each possible failure modes.

The strength data are X₁ Xc, Y₁ = Y, and S (all are in absolute values).

V

!!!!!

a, Ba,