Alander Pasi, Lassila Lippo V J, Vallittu Pekka K
Department of Prosthetic Dentistry and Biomaterials Research, Institute of Dentistry, University of Turku, Lemminkäisenkatu 2, 20520 Turku, Finland.
Dent Mater. 2005 Apr;21(4):347-53. doi: 10.1016/j.dental.2004.05.009.
The aim of this study was to determine experimentally flexural strength and flexural modulus of fiber-reinforced composite (FRC) with different cross-sectional designs and diameters and tested with different span lengths.
Continuous FRC test specimens (n = 6) were made with two different cross-sectional designs, namely circular and rectangular. The resin matrix of FRC was polymerized with a hand light-curing unit followed by a light-curing oven polymerization. Three-point flexural test for determination of ultimate flexural strength and flexural modulus of the dry test specimens was made with different span lengths for rectangular specimens and diameters for circular specimens. Thus, the span length/diameter ratio (L/D) was changed.
Flexural strength and flexural modulus of specimens with rectangular cross-section varied from 540 to 792 MPa and 9.8 to 20.3 GPa being the highest with the group of the 20 mm span length and the lowest with the group of the 10 mm span length. Flexural strength and flexural modulus of circular cross-section specimens varied from 847 to 1286 MPa and 19.9 to 36.6 GPa being the highest with 1.5 mm cross-section and the lowest with 2.8 mm cross-section.
It was concluded, that by increasing the L/D ratio, the flexural strength and flexural modulus values in MPa increased and the maximum fracture load values in N decreased. Reporting the L/D ratio is essential for interpretation of flexural strength and flexural modulus values of small size test specimens.
本研究旨在通过实验确定不同横截面设计、直径且采用不同跨度长度进行测试的纤维增强复合材料（FRC）的抗弯强度和抗弯模量。
制作了连续的FRC测试样本（n = 6），采用两种不同的横截面设计，即圆形和矩形。FRC的树脂基体先用手持式光固化装置进行聚合，然后再用光照固化炉进行聚合。对干燥的测试样本进行三点弯曲试验，以测定其极限抗弯强度和抗弯模量，矩形样本采用不同的跨度长度，圆形样本采用不同的直径。因此，跨度长度与直径之比（L/D）发生了变化。
矩形横截面样本的抗弯强度和抗弯模量在540至792MPa之间以及9.8至20.3GPa之间变化，其中20mm跨度长度组最高，10mm跨度长度组最低。圆形横截面样本的抗弯强度和抗弯模量在847至1286MPa之间以及19.9至36.6GPa之间变化，其中横截面为1.5mm时最高，2.8mm时最低。
得出的结论是，通过增加L/D比，以MPa为单位的抗弯强度和抗弯模量值增加，以N为单位的最大断裂载荷值降低。报告L/D比对解释小尺寸测试样本的抗弯强度和抗弯模量值至关重要。
