Karbhari Vistasp M, Strassler Howard
Materials Science & Engineering Program, and Department of Structural Engineering, MC-0085, University of California San Diego, University Center, La Jolla, CA 92093-0085, USA.
Dent Mater. 2007 Aug;23(8):960-8. doi: 10.1016/j.dental.2006.08.003. Epub 2006 Nov 7.
The aim of this study was to compare and elucidate the differences in damage mechanisms and response of fiber-reinforced dental resin composites based on three different brands under flexural loading. The types of reinforcement consisted of a unidirectional E-glass prepreg (Splint-It from Jeneric/Petron Inc.), an ultrahigh molecular weight polyethylene fiber based biaxial braid (Connect, Kerr) and an ultrahigh molecular weight polyethylene fiber based leno-weave (Ribbond).
Three different commercially available fiber reinforcing systems were used to fabricate rectangular bars, with the fiber reinforcement close to the tensile face, which were tested in flexure with an emphasis on studying damage mechanisms and response. Eight specimens (n=8) of each type were tested. Overall energy capacity as well as flexural strength and modulus were determined and results compared in light of the different abilities of the architectures used.
Under flexural loading unreinforced and unidirectional prepreg reinforced dental composites failed in a brittle fashion, whereas the braid and leno-weave reinforced materials underwent significant deformation without rupture. The braid reinforced specimens showed the highest peak load. The addition of the unidirectional to the matrix resulted in an average strain of 0.06mm/mm which is 50% greater than the capacity of the unreinforced matrix, whereas the addition of the braid and leno-weave resulted in increases of 119 and 126%, respectively, emphasizing the higher capacity of both the UHM polyethylene fibers and the architectures to hold together without rupture under flexural loading. The addition of the fiber reinforcement substantially increases the level of strain energy in the specimens with the maximum being attained in the braid reinforced specimens with a 433% increase in energy absorption capability above the unreinforced case. The minimum scatter and highest consistency in response is seen in the leno-weave reinforced specimens due to the details of the architecture which restrict fabric shearing and movement during placement.
It is crucial that the appropriate selection of fiber architectures be made not just from a perspective of highest strength, but overall damage tolerance and energy absorption. Differences in weaves and architectures can result in substantially different performance and appropriate selection can mitigate premature and catastrophic failure. The study provides details of materials level response characteristics which are useful in selection of the fiber reinforcement based on specifics of application.
本研究旨在比较并阐明基于三种不同品牌的纤维增强牙科树脂复合材料在弯曲载荷下的损伤机制和响应差异。增强类型包括单向E玻璃预浸料（来自Jeneric/Petron Inc.的Splint-It）、超高分子量聚乙烯纤维基双轴编织物（Connect，Kerr）和超高分子量聚乙烯纤维基纱罗织物（Ribbond）。
使用三种不同的市售纤维增强系统制作矩形棒，纤维增强材料靠近拉伸面，对其进行弯曲测试，重点研究损伤机制和响应。每种类型测试八个样本（n = 8）。确定总能量容量以及弯曲强度和模量，并根据所使用结构的不同能力比较结果。
在弯曲载荷下，未增强和单向预浸料增强的牙科复合材料呈脆性破坏，而编织物和纱罗织物增强材料发生显著变形但未破裂。编织物增强样本显示出最高峰值载荷。向基体中添加单向材料导致平均应变达到0.06mm/mm，比未增强基体的能力高50%，而添加编织物和纱罗织物分别使应变增加119%和126%，这强调了超高分子量聚乙烯纤维及其结构在弯曲载荷下保持在一起而不破裂的更高能力。添加纤维增强材料显著提高了样本中的应变能水平，在编织物增强样本中达到最大值，能量吸收能力比未增强情况增加了433%。由于结构细节限制了放置过程中的织物剪切和移动，纱罗织物增强样本的响应具有最小的离散度和最高的一致性。
至关重要的是，不仅要从最高强度的角度，还要从整体损伤容限和能量吸收的角度进行纤维结构的适当选择。编织方式和结构的差异会导致性能有很大不同，适当的选择可以减轻过早和灾难性的失效。该研究提供了材料级响应特性的详细信息，有助于根据具体应用选择纤维增强材料。
