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Effect of Visco-elastic Behavior on Stress Development in a Metal-Ceramic System
P.H. Dehoff
Department of Mechanical Engineering and Engineering Science, University of North Carolina at Charlotte, Charlotte, North Carolina 28223
K.J. Anusavice
Department of Dental Biomaterials, College of Dentistry, University of Florida, Gainesville, Florida 32610
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°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.
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Journal of Dental Research, Vol. 68, No. 8,
1223-1230 (1989)
DOI: 10.1177/00220345890680080201
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