stress_layers

Determining Stress in thin plastic and Ceramic Layers

For testing internal stress of plastic or ceramic layers, it is recommended that you order test strips that have not been selectively coated with resist. The resist will only withstand temperatures below 220 degrees Fahrenheit.Use the test strips for this application as follows:
Apply the plastic or ceramic coating to one side of one leg only as illustrated.S = KU / 3T
S equals KU divided by 3T. Specialty Testing and Development Company supplies the value for the constant, K. T equals the deposit thickness in inches, U equals two times the increments spread, and S equals the deposit stress in pounds per square inch.EXAMPLE: A baked ceramic layer 0.0001 inch thick deflects the strip four units as shown.Spread = 4 increments on the Analyzer Scale,
therefore U = 4 (2) = 8
T = 0.0001 inch
If the value of K = 0. 4300, the deposit stress in
pounds per square inch would become
S = (0. 4300) (8) / 0.0003 = 11,466 PSI