Bistable prestressed symmetric laminates

The bistability of unsymmetric cross-ply [0n/90n]T laminates has already been investigated in much detail. In this work a new type of bistable laminate is presented which has a symmetric lay-up. Bistability derives from an unsymmetric fiber prestress applied to the laminate. The experimental procedure used to apply this fiber prestress is presented in detail. Experimental results are compared with analytical and finite element models which have the ability to model fiber prestress accurately. As well as having minimal hygrothermal variability, it is noted that the snap-through loads for a prestressed symmetric laminate can be much higher than its unstressed [0n/90n]T equivalent.