1 Diagnosis of Deformation Stages with Optical Interferometric Technique and Comprehensive Theory of Deformation and Fracture 3 Crosshead Camera Beam splitter Mirror Laser Beam expander Beam expander Mirror Mirror Crosshead Tensile load y x (a) (b) Fig. 1.1 Experimental setup. (a) and (b) are typical fringe patterns. The dark fringes are highlighted with white dashed lines 0 50 100 150 200 250 300 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 Stress (MPa) Strain (a) (b) (c) (a) (b) (c) Fig. 1.2 Typical fringe patterns representing longitudinal differential displacement at different locations on stress-strain curve where an interferometer sensitive to the in-plane displacement component perpendicular to the tensile axis is added to the configuration. For each pair of images, the left represents the differential displacement component parallel to the tensile axis (vx) and the right represents the component perpendicular (vy). The number above each pair represents the normal strain in the direction of tensile axis. The yield strain was 1.0%. It is seen that the pattern travels at a constant rate along the tensile axis. An important question raised in Fig. 1.3 is if the patterns represent the wave’s characteristics given as solutions to wave Equation (1.1). To examine this question, a finite element analysis was made. This numerical model simply solves wave Equation (1.1), without using any constitutive equation except for Poisson’s ratio. Table 1.2 lists the parameters used for
RkJQdWJsaXNoZXIy MTMzNzEzMQ==