TEMPERATURE-FIELDS IN SLIDING CONTACT BY A HYBRID LASER SPECKLE-STRAIN ANALYSIS TECHNIQUE

A novel methodology to determine the temperature fields associated wit h dry sliding contact is reported. In situ laser speckle photography i s used to measure deformations which occur on the edge of a rectangula r-sectioned pin which is sliding against a counterface disc. A pulsed ruby laser has been employed, and a series of double exposure speckleg rams is made to record deformations that occur between laser pulses. B ased on these deformation histories, the associated strains are obtain ed by the use of the Lagrangian description. The strain at any finite element is resolved into three components: elastic, plastic, and therm al. From an accurately tabulated thermal strain-temperature relation, the temperature fields are determined. Temperatures are obtained for t ypical points at the interface and proximity, not as predictions of ma ximum possible temperatures or as gradients above an average bulk temp erature. These fundamental data trace temperature development historie s for wear specimens, and are essential for the development of wear mo dels. By allowing the investigation of elements of about 25 mu m (that remain inaccessible through conventional methods), the current techni que possesses several advantages with respect to accuracy, accessibili ty and versatility.