Influence of Layer Thickness of the Strength of Angle-Ply Laminates.
VIRGINIA POLYTECHNIC INST BLACKSBURG
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Experimental results are presented showing that the strength and toughness of finite-width angle-ply laminates can be increased significantly by using an alternating layer stacking sequence as opposed to a clustered configuration. The ultimate tensile stress of an alternating plusminus theta aminate of the form or - thetase as much as 1.5 times that of a clustered configuration of the form theta sub 2-theta sub 2s. Further, the toughness of the alternating layer configuration can be as much as 2.7 times that of the clustered configuration. These differences are explained analytically through consideration of the influence of layer thickness on the magnitude of the interlaminar shear stress and by examination of failed specimens. It is shown that the two laminate configurations exhibit distinctly different failure modes for some fiber angles. Both laminates configurations exhibit catastrophic failure with the damage limited essentially to a small region defined by the length of a single crack across the width of the specimen, parallel to the fiber direction. Results are presented for T3OO52O8 graphite-epoxy for fiber orientations of 10 deg, 30 deg, and 45 deg. MM
- Laminates and Composite Materials