Effect of visco-elastic behavior on stress development in a metal-ceramic system.
We developed an analytical model to calculate transient stress and gap displacement during cooling of a porcelainized semicircular arch with a gapped diametral segment. Constant cooling rates were assumed after the specimens were slowly cooled (with power terminated to the furnace) from the porcelain firing temperature. The analytical model incorporates linear visco-elasticity and structural relaxation effects. We calculated transient and residual gap displacements and stresses for a semicircular arch specimen (composed of an experimental opaque porcelain and a Ni-Cr-Be alloy) for six thickness ratios at a cooling rate of 3 degrees C/min. Residual gap displacements were measured for metal-porcelain arch specimens of six thickness ratios. Compared with measured values, calculations based on the visco-elastic theory overestimated gap closure for porcelain/metal thickness ratios below 1.5, and underestimated gap closure at thickness ratios above 1.5.
Dehoff
P H
PH
Department of Mechanical Engineering and Engineering Science, University of North Carolina, Charlotte 28223.
Anusavice
K J
KJ
D002858:Chromium Alloys; D001840:Dental Bonding; D003776:Dental Porcelain; D003799:Dental Stress Analysis; D004548:Elasticity; D006801:Humans; D008422:Materials Testing; D008962:Models, Theoretical; D012044:Regression Analysis; D013499:Surface Properties; D013816:Thermodynamics; D014783:Viscosity
D002858:Chromium Alloys; D003776:Dental Porcelain