Multicycle Indentation for Evaluation of Polymer Material Viscoelastic Characteristics

The evaluation of viscoelastic characteristics by an indentation test is required in order to separate the viscoelastic deformation and plastic deformation from the measured penetration depth. In this study, a multicycle indentation test is performed in order to separate these deformations and to evaluate the viscoelastic characteristics of acrylonitrile butadiene styrene (ABS) and polybutylene terephthalate (PBT). In the multicycle indentation test, two or more indentation tests are conducted at the same specimen position. After the first cycle, the indentation test is performed on the impression; thus, an evaluation formula for obtaining the viscoelastic characteristics is proposed, and the validity of this formula is confirmed by finite element analysis. As a result, the evaluated creep compliances of both materials are close the value evaluated by tensile testing. Therefore, it is concluded that the proposed method is applicable to the evaluation of viscoelastic characteristics.