Host: The Japan Society of Mechanical Engineers
Name : [in Japanese]
Date : September 15, 2021 - September 17, 2021
The small punch test and the small punch creep test are performed by pushing a small disc-shaped specimen of φ3~10mm x t0.5mm in diameter with a ball of 2~2.5mm in diameter. Since it is a micro specimen, it is possible to obtain strength properties at locations that cannot be sampled with a normal specimen. In addition, it is possible to evaluate the local strength. In this study, we examined the applicability of the small punch test and small punch creep test to thermoplastic resin. Four types of thermoplastic resin were used as specimens: 6 nylon (PA6), polyethylene terephthalate (PET), polycarbonate (PC), and polytetrafluoroethylene (PTFE). In the small punch test, the load required for rupture was higher for PC, PET, PA6, and PTFE, in that order. The conversion equations from small punch test results for tensile strength and ductility have been proposed. However, good agreement was not always obtained for resin materials. The coefficients for tensile strength needed to be changed, and the results for ductility at break were far off depending on the material type. In the small-punch creep test, only PTFE ruptured prematurely when 90% of the maximum load in the small-punch test was applied. While the initial strains of PA6, PC, and PET were different, but the displacement rate was similar. For both the small punch and small punch creep tests, PTFE showed a different trend from the other resin materials. From the viewpoint of the molecular structure, the influence of intermolecular forces may be significantly larger.
