Applying ASTM Standards to Tensile Tests of Musculoskeletal Soft Tissue: Methods to Reduce Grip Failures and Promote Reproducibility.

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.

Print-A-Punch: A 3D printed device to cut dumbbell-shaped specimens from soft tissue for tensile testing.

The failure behavior and mechanical properties of soft tissue can be characterized by conducting uniaxial tensile tests on small sectioned specimens, called test coupons. An ideal coupon geometry for tensile testing is a dumbbell shape (dog-bone), yet the cost and time required to fabricate custom steel punches to cut dumbbell-shaped coupons has hindered their universal application in biomechanics research. In this study, we developed an economical and reliable cutting device that can extract dumbbell-shaped coupons from soft biological tissue.

Fatigue life of bovine meniscus under longitudinal and transverse tensile loading.

The knee meniscus is composed of a fibrous extracellular matrix that is subjected to large and repeated loads. Consequently, the meniscus is frequently torn, and a potential mechanism for failure is fatigue. The objective of this study was to measure the fatigue life of bovine meniscus when applying cyclic tensile loads either longitudinal or transverse to the principal fiber direction.