Joint stiffness factor
 Diameter bolt d mm
 Young's modulus bolt E GPa
 Thickness clamped material lm mm
 Young's modulus clamped material E GPa
 Bolt stiffness kb=AE/lm 109 N/m
 Diameter d2=1.5d mm
 Diameter d3=d2+lmtan(φ), φ=30 mm
 Stiffness clamped material km 109 N/m
 Joint stiffness factor1) Cm=kb/(kb+km)

1) For simplicity, the clamped materials are frequently assumed to have a stiffness of three times the bolt stiffness, which results in a joint stiffness factor of Cm=1/4. With Cm=1/4, it follows that only one fourth of the applied load P is taken by the bolt.