Tensile testing of thin plastic sheeting in accordance with ASTM D882 is a common testing requirement for many of our customers. Gripping of these delicate specimens is the prevalent challenge in most tests. The gripping technique must prevent slipping of the material at high loads but not tear into the material and cause premature specimen failure.
We conducted this testing in order to recommend a set of grips and faces that would prevent slipping of the plastic sheeting during tensile testing and not lead to specimen failure.
For this test, we used a Model 3345 Electromechanical system with a 225 lb load cell. We found the 1 inch x 1 inch rubber-coated faces on the 225 lb capacity pneumatic side-action grips and a gripping pressure of 90 psi to be successful in achieving the goal. The rubber-coated faces cushioned the specimen at high loads and the large capacity grips allowed for an increased gripping force to prevent slipping. We evaluated each specimen for slipping by marking the position of the faces on the material with a black permanent marker. Material failure occurred within the gauge area for every specimen.
We recommend reading and reviewing ASTM D882 in order to fully understand the test setup, procedures, and results requirements.