Joint Stiffness Factor

Bolt and clamped-material stiffness (cone model, φ = 30°). Often C_m ≈ 1/4 when k_m ≈ 3 k_b.

Cone model: head pressure spreads through the clamped plates at φ = 30°, forming the effective compression zone between d₂ = 1.5d and d₃ = d₂ + l_m tan φ. Schematic only, not drawn from inputs.

Section A

User inputs

Bolt diameter d mm

Young’s modulus bolt E GPa

Clamped thickness l_m mm

Young’s modulus clamped part E GPa

Key results

Bolt stiffness k_b

—

Clamped stiffness k_m

—

Joint factor C_m

—

Load on bolt share

Cone diameter d₂ = 1.5 d	—	mm
Cone diameter d₃	—	mm	d₂ + l_m tan 30°
Clamped area A_m	—	mm²	π/4[(d₂+d₃)/2]² − d²

k_b = A_bE/l_m; k_m = A_mE/l_m; C_m = k_b/(k_b+k_m).