Dehoff P H, Anusavice K J
Department of Mechanical Engineering and Engineering Science, University of North Carolina, Charlotte 28223.
J Dent Res. 1989 Aug;68(8):1223-30. doi: 10.1177/00220345890680080201.
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.
我们开发了一个分析模型，用于计算带有径向间隙段的瓷化半圆形牙弓冷却过程中的瞬态应力和间隙位移。假设在将试样从烤瓷温度缓慢冷却（关闭炉子电源）后，冷却速率恒定。该分析模型纳入了线性粘弹性和结构松弛效应。我们以3℃/分钟的冷却速率，针对六种厚度比的半圆形牙弓试样（由实验性不透明瓷和镍铬铍合金组成）计算了瞬态和残余间隙位移及应力。对六种厚度比的金属烤瓷牙弓试样测量了残余间隙位移。与测量值相比，基于粘弹性理论的计算对于瓷/金属厚度比低于1.5的情况高估了间隙闭合，而对于厚度比高于1.5的情况则低估了间隙闭合。
