Comparative study of modeling and experiments in precision crack off method

• Main Author: Subramaniyam, Sathiya Velan.
• Other Authors: Sathyan Subbiah
• Format: Final Year Project
• Language: English
• Published: 2010
• Subjects: DRNTU::Engineering::Mechanical engineering::Mechanics and dynamics; DRNTU::Engineering::Mechanical engineering::Assistive technology
• Online Access: http://hdl.handle.net/10356/41622
• Institution: Nanyang Technological University

Thin slices of silicon are generated from the cast ingots in the solar or electronics industry to manufacture solar cells or Integrated Circuits (IC) respectively. Currently, wire sawing technique that is used in the industry takes 50% of total operational cost due to high kerf (material) loss and time consumption. The technique to generate such thin slices has to be suitable for mass manufacturing silicon wafers and must also reduce/eliminate silicon wastage during the wafering process. This project has tested and developed a fast cracking method to mass manufacture thin slices in brittle materials such as glass and silica. The idea to introduce a small crack on the surface of a brittle material, place it in a high pressure chamber and apply pressure on the crack is termed as precision crack off. At a suitable crack geometry and pressure, conditions for fast fracture are satisfied and the crack travels at high speed through the specimen slicing it and leaving a smooth atomic surface on the crack faces. This concept is also tested in finite element simulation using Johnson Holmquist (JH) fracture model in ANSYS AUTODYN. Hence, the results of the experiments and modeling are compared hence possible improvements are suggested. The design developed to test precision crack off method yielded broken glass pieces with good surface finish. The different notch depths have produced relationship among notchpressure, pressure-surface finish, unconstrained and constrainted experiments. These results were also validated in finite element simulation of ANSYS AUTODYN. Besides that, finite element simulation has solved the puzzle of crack initiation and propagation. Finite element analysis helped a lot in understanding the theory behind precision crack method. New initiative of validating JH model for precision crack off method has yielded fruitful results.