PSI - Issue 42

Erik Calvo-García et al. / Procedia Structural Integrity 42 (2022) 251–258 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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experimentally determined at different loading conditions, while a 0.23 Poisson’s ratio was employ ed. The flexural strength was experimentally determined using a four-point loading configuration according to ASTM c158 standard in a Walter-Bai axial testing machine with 25-kN maximum axial load. Sharp edge and beveled edge specimens were tested to avoid masking the failure mechanism and reveal the true influence of the laser surface treatment. Strain measurements during testing were performed by resistive strain gauges.

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Figure 1. Schematics of the laser technique applied for the modification of soda-lime silicate glass by laser blasting: a) unmodified reference glass; b) pulsed CO 2 laser surface modification; c) continuous operation CO 2 laser surface modification. The glass plate height is 60 mm. 3. Results and discussion The reference glass surface and the laser blasted surface is show in Fig. 1.b-d. Both laser processing under pulsed operation (interrupted optical power), and continuous wave operation (constant optical power) is feasible with this experimental system. The surface roughness and treatment depth and can be controlled within Rz 10 to 100 micrometer as a function of the optical power reaching the glass surface, which can be set by the laser source output power and the translation stage speed. Thus, the surface roughness is continuously increased as the processing speed decreases.

Figure 2. Influence of the processing stage speed during the laser blasting process on the slip angle on dry conditions. Slip direction parallel to the blasted surface pattern and perpendicular to the blasted surface pattern is shown. The red line show slip angle of reference unmodified glass. Nevertheless, the measured slip angle does not increase constantly with the reduction of processing speed, see Fig. 2. Instead, an almost constant improvement of slip angle is obtained for most of the laser energy density range tested.