Brittle Coating - Problem Solution Procedure

Stress in the part in the x-direction at coating fracture

General Concept: At coating fracture the strain in the coating is known, since the coating fracture strain was ascertained in a coating calibration test. At the coating fracture state the strain in the coating and part are the same.


sp = Ep ep
The strain in the part is equal to the strain in the coating so
ep = efc
The modulus of elasticity of the part material, Ep, is known and
sp = Ep efc

Cross-sectional area of the part

General Concept: Force F = sp Ap and the force acting on the part at coating fracture is known. The stress at the load needed to cause coating fracture was calculated above.


A = F / sp

© 2001 by Barney E. Klamecki. All rights reserved