MEASUREMENT OF SLIDER-DISK COLLISION FORCES USING ACOUSTIC-EMISSION SOURCE WAVE ANALYSIS

A new measuring technique has been developed for the purpose of analyz ing the slider/disk collision phenomena. Very small piezoelectric sens ors are mounted on the slider. These sensors detect elastic waves (aco ustic emission) in the slider which are induced by the collisions at t he slider rail surface. In order to obtain input collision force quant itatively, the transfer function of the slider, sensor, and electric c ircuit is measured by the breaking pencil lead method. The inverse ope ration is also performed by using source wave analysis. Force amplitud e of the order of 4-20 mN and contact time of the order of 5-22 mus ar e detected. Two types of collision force are observed. One has large a mplitude and narrow time width and is conjectured to arise from collis ions with hard projections. The other has small amplitude and wide tim e width and is conjectured to arise from collisions with soft projecti ons.