Stability of triple-layer shells made of composite materials under combined axial compression and lateral pressure

Abstract

1. On the basis of generalized stiffnesses, analytical methods of stability analysis have been developed for triple-layer cylindrical shells under axial compression, under external pressure, or under both combined. Simple calculation formulas have been derived for this. 2. The stability of triple-layer cylindrical shells under combined axial compression and external pressure has been analyzed. The results reveal that the mutual influence of axial compression and external pressure is small, or vanishes during axisymmetric wave formation, in the case of shells with a filler which is weak in shear (K1≤1/2T10S). In the case of shells with a filler which is stiff in shear (K1>1/2T10S) this influence is of the same order as in the case of shells with an invariable normal. 3. The reinforcing effect of internal pressure, in terms of the critical axial force, is small in the case of shells with a filler which is weak in shear and vanishes altogether during axisymmetric wave formation. In the case of orthotropic shells with a filler which is stiff in shear this reinforcing effect of internal pressure is of the same order as in the case of shells with an invariable normal.