Thermal contact conductance: effect of overloading and load cycling

An experimental investigation is carried out to study the effects on joint conductance of progressive loading and unloading, cyclic loading and overloading to a predetermined value. The test pair used is AISI 304 stainless steel, bead blasted to an effective rms surface roughness of 7.55 (mu)m and a slope of 0.36 rad. In all cases a hysteresis loop is seen to exist for the loading unloading cycle and is seen to decrease with increasing number of cycles. The conductance values eventually appear to settle down to values higher than those obtained during first loading. Enhancement of contact conductance by cyclic loading is found to be rather small. On the other hand overloading the test pairs to a predetermined contact pressure is found to be promising.