Thermographic Techniques for Inspection of Babbitted Bearings

摘要

The report describes the investigation of several thermographic (infrared) techniques and their applicability to the detection of unbonded areas in babbitted bearings. Standard defect samples were prepared with films of oil and grease between layers of babbitt and steel. These samples were systematically investigated by techniques designed to (1) detect a 'thermal shadow' in an arrangment providing an equilibrium heat flux through the sample, or (2) detect differences in the time required for different areas of the sample to dissipate an impulse of heat. The results indicate that several techniques are capable of detecting unbonded areas and that a technique of measuring the return of the sample surface to equilibrium temperature following a thermal impulse was most sensitive to the sample defects. A design was developed to improve the technique. Some ultrasonic test results and some time-averaged interference holograms are also presented. (Author)