Measurements of tangential stiffness and damping of mechanical joints: Direct versus indirect contact resonance methods

► Fretting loop measurements achieve better results when the joint is compliant (polymers, elastomers, loose joints). ► Stiff joints at practical loading cases are better measured with the contact resonance method. ► Aluminum joints show a stiffness varying from 40 to 170 MN/m depending on the normal preload imposed by the bolts. ► Smooth joints exhibit more compliant responses. ► Lubrication increases the overall joint damping.