Naik P R, Duncanson M G, Mitchell D L, Wiebelt F J, Johnson D L, Ghosh J
Department of Removable Prosthodontics, University of Oklahoma, College of Dentistry, Oklahoma City 73190, USA.
J Prosthodont. 1997 Mar;6(1):43-54. doi: 10.1111/j.1532-849x.1997.tb00064.x.
Three-dimensional models of half-round, tapered and full-round, untapered I-bar clasps of varying configurations and material properties were constructed. The purpose of this study was to examine the stresses and reaction forces produced within each model upon deflection to 0.01 in (0.254 mm), 0.02 in (0.508 mm), and 0.03 in (0.762 mm) at 1 mm from the tip using the finite element method.
Three-dimensional computer models of half-round and full-round clasps were constructed using solid eight-node brick elements. The half-round, tapered I-bar clasp model was 2.4 and 1.4 mm in diameter at the base and tip, respectively. The full-round, untapered I-bar clasp model was 1 mm in diameter. Three design groups were created for each clasp form. Group A had 25% of the total length in the straight anchor end of the I-bar clasp, B had 35%, and C had 50%. All models were 31 mm in length and had a radius of curvature of 5 mm. Different material properties were incorporated into the models. Each model was deflected at a point 1 mm from the tip to 0.01 in (0.254 mm), 0.02 in (0.508 mm), and 0.03 in (0.762 mm).
The stresses and forces produced as a result of the deflection applied to each clasp were viewed and displayed graphically. The maximum von Mises stresses in megapascals and the reaction force in newtons (N) were recorded. Stresses varied in each clasp in the range of 0 to 154.3 MPa for the half-round, tapered I-bar clasp models, and 0 to 100.9 MPa for the full-round I-bar clasp models at 0.01-in deflection. Reaction force measured near the tip of the clasp models was between 1.60 N and 6.31 N for the half-round, and between 0.22 N to 2.13 N for the full-round I-bar clasp models. For all clasps studied, as the deflection increased, the location of stress within each group remained the same regardless of the material properties; however, the stress and force values increased linearly.
The location of maximum stress varied with the length of the anchor portion of the clasps studied. Maximum stresses were located on the flat side of the half-round, tapered I-bar clasp model.
构建了不同结构和材料特性的半圆形、锥形以及全圆形、无锥度I型卡环的三维模型。本研究的目的是使用有限元方法，研究每个模型在距尖端1毫米处挠度达到0.01英寸（0.254毫米）、0.02英寸（0.508毫米）和0.03英寸（0.762毫米）时产生的应力和反作用力。
使用实体八节点砖块单元构建半圆形和全圆形卡环的三维计算机模型。半圆形、锥形I型卡环模型在基部和尖端的直径分别为2.4毫米和1.4毫米。全圆形、无锥度I型卡环模型的直径为1毫米。为每种卡环形式创建了三个设计组。A组在I型卡环的直锚固端占总长度的25%，B组占35%，C组占50%。所有模型的长度均为31毫米，曲率半径为5毫米。将不同的材料特性纳入模型。每个模型在距尖端1毫米处挠度达到0.01英寸（0.254毫米）、0.02英寸（0.508毫米）和0.03英寸（0.762毫米）。
观察并以图形方式显示了施加到每个卡环上的挠度所产生的应力和力。记录了以兆帕为单位的最大冯·米塞斯应力和以牛顿（N）为单位的反作用力。对于半圆形、锥形I型卡环模型，在0.01英寸挠度时，应力在0至154.3兆帕范围内变化，对于全圆形I型卡环模型，应力在0至100.9兆帕范围内变化。在卡环模型尖端附近测得的反作用力，对于半圆形卡环在1.60牛至6.31牛之间，对于全圆形I型卡环模型在0.22牛至2.13牛之间。对于所有研究的卡环，随着挠度增加，每组内应力的位置保持不变，与材料特性无关；然而，应力和力值呈线性增加。
最大应力的位置随所研究卡环锚固部分的长度而变化。最大应力位于半圆形、锥形I型卡环模型的平面一侧。
