Study of Dynamic Behavior of Multilayered Clamped Composite Skewed Hypar Shell Roofs under Impact Load

Table 1

Nondimensional natural frequencies (𝜛) for a three-layer graphite epoxy twisted plate.

Angle of twist 𝜃 (deg)	0	15	30	45	60	75	90
𝜙=15^∘
Qatu and Leissa [17]	1.0035	0.9296	0.7465	0.5286	0.3545	0.2723	0.2555
Present formulation	0.9990	0.9257	0.7445	0.5279	0.3542	0.2720	0.2551
𝜙=30^∘
Qatu and Leissa [17]	0.9566	0.8914	0.7205	0.5149	0.3443	0.2606	0.2436
Present formulation	0.9490	0.8842	0.7181	0.5142	0.3447	0.2613	0.2444

𝐸₁₁=138 GPa, 𝐸₂₂=8.96 GPa, 𝐺₁₂=7.1 GPa, 𝜈₁₂=0.3, 𝑎/𝑏=1, 𝑎/ℎ=100.