Department of Mechanical & Biomedical Engineering, Boise State University, Boise, ID 83725-2085.
Micron School of Materials Science and Engineering, Boise State University, Boise, ID 83725-2085.
J Biomech Eng. 2021 Jan 1;143(1). doi: 10.1115/1.4048646.
Tensile testing is an essential experiment to assess the mechanical integrity of musculoskeletal soft tissues, yet standard test methods have not been developed to ensure the quality and reproducibility of these experiments. The ASTM International standards organization has created tensile test standards for common industry materials that specify geometric dimensions of test specimens (coupons) that promote valid failures within the gage section (midsubstance), away from the grips. This study examined whether ASTM test standards for plastics, elastomers, and fiber-reinforced composites are suitable for tensile testing of bovine meniscus along the circumferential fiber direction. We found that dumbbell (DB) shaped coupons based on ASTM standards for elastomers and plastics had an 80% and 60% rate of midsubstance failures, respectively. The rate of midsubstance failures dropped to 20% when using straight (ST) coupons based on ASTM standards for fiber-reinforced composites. The mechanical properties of dumbbell shaped coupons were also significantly greater than straight coupons. Finite element models of the test coupons revealed stress distributions that supported our experimental findings. In addition, we found that a commercial deli-slicer was able to slice meniscus to uniform layer thicknesses that were within ASTM dimensional tolerances. This study provides methods, recommendations, and insights that can advance the standardization of tensile testing in meniscus and other soft fibrous tissues.
拉伸测试是评估肌肉骨骼软组织机械完整性的重要实验，但尚未制定标准测试方法来确保这些实验的质量和可重复性。美国材料与试验协会（ASTM International）标准组织已经为常见的工业材料制定了拉伸测试标准，这些标准规定了测试样品（试件）的几何尺寸，以促进在量规部分（物质中部）发生有效的失效，远离夹具。本研究探讨了 ASTM 针对塑料、弹性体和纤维增强复合材料的测试标准是否适用于沿圆周纤维方向对牛半月板进行拉伸测试。我们发现，基于 ASTM 弹性体和塑料标准的哑铃形试件（DB）的物质中部失效率分别为 80%和 60%。当使用基于 ASTM 纤维增强复合材料标准的直型试件（ST）时，物质中部失效率降至 20%。哑铃形试件的机械性能也明显大于直型试件。测试试件的有限元模型揭示了支持我们实验结果的应力分布。此外，我们发现商用切肉机能够将半月板切成符合 ASTM 尺寸公差的均匀层厚。本研究提供了可以推进半月板和其他软纤维组织拉伸测试标准化的方法、建议和见解。
