DETERMINATION OF RESIDUAL-STRESS IN COATINGS BY A MEMBRANE DEFLECTIONTECHNIQUE

A membrane deflection technique has been developed to measure the isot ropic residual stress in biaxially-constrained coatings. The technique has been demonstrated on various materials, including polyimide, late x rubber and photoresist coatings. Stress values obtained from membran e deflection compared well with results obtained from time-averaged vi brational holographic interferometry except for values obtained from s amples where rigidity effects were found to be important. A criterion based on the thickness, rigidity, stress and sample radius is also dis cussed, establishing the applicability of the technique to samples of low rigidity.