Mechanical test on different elastomer materials based on the ASTM D412-16 standard
Creators: name: Hatami, Mohsen
name: Kent, Nicholas
name: Whyte, Thomas
name: E. Bilston, Lynne
Publisher: name: Zenodo
Year: 2024
Subjects: Stress-strain curve of EPDM rubber
Stress-strain curve of natural rubber
Sress-strain curve of polyurethane material
ASTM D412-16 tensile testing
Mechanical properties
strain rate sensitivity
stress-strain curve of neoprene rubber
tensile strength
High strain rate tensile testing
Natural rubber strength
EPDM rubber strength
Neoprene rubber strength
Strength of Polyurethane
Natural rubber
EPDM rubber
Neoprene rubber
Polyurethane
Mechanical property of polyurethane
Mechanical properties of natural rubber
Mechanical properties of polyurethane
Mechanical properties of neoprene rubber
Mechanical properties of EPDM rubber

description: Aim: The main goal of conducting the mechanical tensile tests was to produce non-linear stress-strain curves for input data in the Ansys Workbench software. These curves played an important role in the accurate analysis of the mechanical behavior of the Finite Element Model (FEM) of the Hybrid III 5% Female ATD lumbar spine prototype. In addition, these curves evaluated the suitability of elastomer materials for manufacturing the lumbar spine prototype.

Method: Fourty-five Mechanical tensile tests were performed on five different elastomer materials (NR60, EPDM60, NEO60, CCP60, and CCP80) based on the ASTM D412-16 standard at three different strain rates including the standard strain rate (0.32 or =8mm/s), moderate strain rate (0.64 or =16mm/s), and high strain rate (4 or =100mm/s). Samples with standard and moderate strain rates were taken to failure using the MTS Insight 2 tensile testing machine. However, samples were not taken to failure in high strain rate testing due to the limited crosshead displacement (100mm) of the tensile testing machine (MTS 858 Bionix). 

Result: The EPDM60 material with a tensile strength of 9.6 MPa demonstrated minimal Strain Rate Sensitivity (SRS =-0.06) up to 100% strain. The NR60 and CCP80 materials had greater tensile strength (18.5 MPa and 14.8 MPa) than EPDM60, but medium strain rate sensitivity (SRS -0.11 and -0.15). The CCP60 and NEO60 materials had lower tensile strength (5.3 MPa and 4.8 MPa) than EPDM60, but the medium (SRS =-0.12) and maximal strain rate sensitivity (SRS=-0.3), respectively.

Conclusion: The EPDM60 and NR60 materials appeared to be suitable for manufacturing the lumbar spine prototype, as EPDM60 exhibits minimal SRS, whereas NR60, despite a slight difference with a minimal range of SRS, showed maximal strength. Results of the FEM analysis showed that the lumbar spine prototype by using NR60 performs better than EPDM60. Therefore, NR60 as a suitable material was selected for manufacturing the lumbar spine prototype.
description: Funding provided by: National Health and Medical Research CouncilCrossref Funder Registry ID: https://ror.org/011kf5r70Award Number: APP1172988
description: Mechanical tensile tests were conducted to define nonlinear stress-strain curves and assess the suitability of elastomer materials for the Hybrid III 5% Female ATD lumbar spine prototype. These elastomer materials include the Natural Rubber 60±5 shore A (NR60), Ethylene Propylene Diene Monomer rubber 60±5 shore A (EPDM60), Neoprene Rubber 60±5 shore A (NEO60), Cold Castable Polyether 60±5 shore A (CCP60), and Cold Castable Polyether 80°±5° shore A (CCP80). Mechanical tensile tests were performed based on procedures in ASTM D412-16 standard. Tension samples were prepared in a dog bone geometry (Die C). Width and thickness were measured for each specimen. The gauge length of each sample was considered 25±0.25mm in mechanical tests. Thirty tensile tests at the standard (0.32 or =8mm/s) and moderate (0.64 or =16mm/s) strain rates and fifteen tensile tests at high (4 or =100mm/s) strain rate, were conducted by the MTS Insight 2 and MTS 858 Bionix tensile testing machines, respectively. Samples with the standard and moderate strain rates were taken to failure. Samples were not taken to failure in high strain rate testing due to the limited crosshead displacement (50mm) of the tensile testing machine.