Host: The Japan Society of Mechanical Engineers
Name : [in Japanese]
Date : October 08, 2016 - October 10, 2016
Polyimide (PI) film with a surface small defect subjected to tensile load is fractured by the crack propagation from the defect in the film thickness direction. However, the evaluation method of fracture toughness in this type of fracture hasn’t yet been established. In this paper, SENT tests were carried out using 125 μm-thick PI films with a surface pre-crack having different depths from 10 μm to 60 μm, and fracture processes focusing on crack opening and crack extension were observed with a color 3D laser scanning microscope. Based on the results, fracture toughnesses Jin in the direction of film thickness were calculated by using two different equations for SENT specimen. As a result, Jin values were clarified to have a slight dependency on pre-crack depth. The differences between Jin values calculated by the two equations were considered small, and fracture toughness was in the range from 0.4 to 1 kJ/m2.
