Behaviour and Optimization Aids of Composite Stiffened Hypar Shell Roofs with Cutout under Free Vibration

Figure 5

Values of non-dimensional fundamental frequency (𝜔) of 0/90/0/90 stiffened hypar shell with cutout for different sizes of central cutout and boundary conditions; 𝑎/𝑏=1, 𝑎/ℎ=100, 𝑎^/𝑏^=1, 𝑐/𝑎=0.2; 𝐸₁₁/𝐸₂₂=25, 𝐺₂₃=0.2𝐸₂₂, 𝐺₁₃=𝐺₁₂=0.5𝐸₂₂, 𝜈₁₂=𝜈₂₁=0.25, 𝑏_st/ℎ=1, 𝑑_st/ℎ=2. Each stiffener has a single lamina with fibres along its length.