A pseudo ductile angle-ply sub-laminate approach for multidirectional thin ply CFRP laminates

Analytical modelling of thin ply angle-ply [±θ/0]_s carbon-epoxy layups consisting of intermediate modulus MR60 and ultra high modulus YSH70A prepreg materials has been conducted to establish a candidate configuration for use as a pseudo-ductile sub-laminate in a multidirectional laminate. These layups have demonstrated considerable pseudo-ductility via gradual failure of the 0° ply. Stress-strain predictions of [±25/0]_s, in particular, have shown that this layup possesses a high initial modulus of 135 GPa and produce a pseudo-ductile strain of 1.43%, for a strength of 761 MPa. Selected as a sub-laminate configuration, this layup has been applied to two stacking sequences: [30/0/ - 30]_s and [45/0/ - 45]_s, where the global orientations correspond to the direction of the 0° ply in each sub-laminate. Classical laminate analysis indicates that these multidirectional laminates can exploit the pseudo-ductility of the sub-laminates to achieve a gradual failure at a higher scale.