PSI - Issue 14

Mohd Tauheed et al. / Procedia Structural Integrity 14 (2019) 354–361 Mohd Tauheed/ Structural Integrity Procedia 00 (2018) 000–000

357

4

Load cell

DCB Fixture

DCB

Vertical slide

Camera & Lens

Support Fixture

Fig. 2. Experimental setup for DCB test

A 35 mm fixed focal length lens along with extension tubes were used to achieve an approximate field of view of 3 mm × 3 mm, and the resolution achieved was about 1.5 µm/pixel. The camera and lens were mounted on a manual vertical slide to facilitate the vertical motion of the camera and track the crack tip during loading of the specimen. �� � � ��� � � � � � ��� (1)

Fig 3. (a) Evolution of G I with separation δ for the DCB specimen (b) Experimentally obtained and bilinear approximations for mode I traction separation law for the DCB specimens at a fixed crack length. 2.1. Determination of Mode I Traction-separation Law The traction-separation law represented � �� � is obtained by differentiating the following equation as described in de Moura et al. (2012), ��������� � � � � � � � � (2) This leads to, traction value at any point,