External pressure design primarily prevents?

• A. Buckling Collapse
• B. Fatigue
• C. Thermal Cracking
• D. Yielding

Answer: (A)

External pressure design focuses on stability under outside compression. When a shell is subjected to external pressure, it can lose its rigidity and buckle—the shape becomes unstable long before the material yields. This buckling is a geometric instability driven by the external load and the shell’s geometry, thickness, and boundary conditions, so the design’s main goal is to keep the external pressure below the critical buckling (collapse) value. Fatigue, thermal cracking, and yielding are concerns in other scenarios—fatigue with cyclic loads, thermal cracking from temperature gradients, and yielding from stresses exceeding the material’s yield strength under internal or combined loads—but they are not the primary failure mode for external pressure.