How do you design a multi-leaf spring for a vehicle suspension?

Design involves determining load capacity, deflection, and stress distribution. For a semi-elliptic leaf spring, deflection delta = 6PL^3/(Enbt^3) and stress sigma = 6PL/(nbt^2), where P is load, L is span, n is number of leaves, b is width, t is thickness. Graduated leaves contribute partially to bending resistance. Include nipping (initial curvature difference) to equalize stress. Consider rebound clips, center bolt strength, and interleaf friction. Material is typically 55Si7 or 50Cr4V2 spring steel.