3-DIMENSIONAL FINITE-ELEMENT ANALYSIS OF THE SHEAR BOND TEST
3-DIMENSIONAL FINITE-ELEMENT ANALYSIS OF THE SHEAR BOND TEST
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DOI：
10.1016/0109-5641(95)80047-6
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发表时间：
1995-03-01
期刊：
影响因子：
5
通讯作者：
WANG, ZX
中科院分区：
文献类型：
--
作者：
DEHOFF, PH;ANUSAVICE, KJ;WANG, ZX
目标.本研究的目的是使用有限元分析来模拟平面剪切粘结试验，并评估模量值、粘结剂厚度和加载条件对粘结剂-牙本质界面附近牙本质应力分布的影响。所有计算均采用ANSYS有限元程序进行。平面剪切粘结试验被建模为树脂基复合材料的圆柱体粘结到圆柱形牙本质基质。材料、几何形状和载荷变量的影响主要通过使用三维结构元素来确定。几次运行也使用轴对称元素与谐波加载和平面应变元素，以确定是否二维分析产生有效的结果。使用三维有限元分析的应力计算证实了在施加载荷附近的粘结剂-牙本质界面处的所有应力分量存在大的应力集中效应。最大垂直剪应力一般出现在加载点以下约0.3 mm处，然后在所有方向上急剧下降。应力在加载点约0.5mm内达到相对均匀的条件，然后随着接近界面的下部区域而再次增加。使用各种加载条件的计算表明，线环加载方法导致较小的应力集中效应，但是通过将失效载荷除以横截面积确定的剪切粘结强度严重低估了真实的界面粘结强度。大多数牙科研究人员正在使用拉伸和剪切粘结试验来预测工艺和材料变量对粘结系统临床性能的影响，但尚无证据表明粘结强度与临床性能相关。评估粘结试验有效性的一个关键因素是彻底了解导致粘结试验失败的应力状态，然后评估这些应力状态是否也存在于临床情况中。有限元分析可以帮助回答这个问题，但需要更多的工作，以确定在服务中的故障模式，并将这些故障与特定的负载条件。目前的研究只是了解平面剪切粘结试验中应力状态的第一步。
Objectives. The purpose of this study was to use finite element analyses to model the planar shear bond test and to evaluate the effects of modulus values, bonding agent thickness, and loading conditions on the stress distribution in the dentin adjacent to the bonding agent-dentin interface.Methods. All calculations were performed with the ANSYS finite element program. The planar shear bond test was modeled as a cylinder of resin-based composite bonded to a cylindrical dentin substrate. The effects of material, geometry and loading variables were determined primarily by use of a three-dimensional structural element. Several runs were also made using an axisymmetric element with harmonic loading and a plane strain element to determine whether two-dimensional analyses yield valid results.Results. Stress calculations using three-dimensional finite element analyses confirmed the presence of large stress concentration effects for all stress components at the bonding agent-dentin interface near the application of the load. The maximum vertical shear stress generally occurs approximately 0.3 mm below the loading site and then decreases sharply in all directions. The stresses reach relatively uniform conditions within about 0.5 mm of the loading site and then increase again as the lower region of the interface is approached. Calculations using Various loading conditions indicated that a wire-loop method of loading leads to smaller stress concentration effects, but a shear bond strength determined by dividing a failure load by the cross-sectional area grossly underestimates the true interfacial bond strength.Significance. Most dental researchers are using tensile and shear bond tests to predict the effects of process and material variables on the clinical performance of bonding systems but no evidence has yet shown that bond strength is relevant to clinical performance. A critical factor in assessing the usefulness of bond tests is a thorough understanding of the stress states that cause failure in the bond test and then to assess whether these stress states also exist in the clinical situation. Finite element analyses can help to answer this question but much additional work is needed to identify the failure modes in service and to relate these failures to particular loading conditions. The present study represents only a first step in understanding the stress states in the planar shear bond test.