A Study on Local Compression Behavior of Brake Friction Materials by Means of Digital Image Correlation Method

The inhomogeneous compressive strain behavior of the friction material was analyzed by means of digital image correlation method (DICM). Macroscopic strain of the sample without a cashew decreased monotonically with the increasing molding pressure, and DICM analysis indicated homogeneous strain distribution. While sample containing cashew showed a peculiar molding pressure dependence in macroscopic strain, which the strain increased remarkably above 30 MPa. The result of DCIM analysis indicated that the void structure introduced by the spring-back periphery of cashew caused the inhomogeneous strain distribution as well as larger deformation upon the compressive load. It was also found that the addition of cashew and mica greatly enhanced the void formation.