Date of Award
Doctor of Philosophy
The two main objectives of this work is 1) to develop a mathematical model to efficiently capture the fracture behavior of materials undergoing thermal shock and 2) to design and develop a mechanics based hybrid laser/waterjet manufacturing process that will be able to machine hard and brittle materials at higher speeds and with better cut quality. The mathematical model relates the temperature generated during the machining process to the fracture behavior observed during machining. The hybrid manufacturing processes produces a synergetic effect of both laser and waterjet processes and overcomes the disadvantages of both of them.
The temperature distribution is obtained from the Green's solution of the Fourier Heat Conduction equation. Uncoupled thermoelastic stresses are obtained from the temperature distribution which in-turn is related to the stress intensity factor/Griffith Energy for Mode I crack growth by Bueckner's weight function approach. This model can also be used to predict fracture behavior for given laser processing conditions. This model can also be used to manipulate transformational stresses that occur during machining of high conductive materials. This model can be easily extended to many multi-physics problems involving thermo-elastic behavior.
Kalyanasundaram, Dinesh, "Mechanics guided design of hybrid laser/waterjet system for machining of hard and brittle materials" (2009). Graduate Theses and Dissertations. Paper 10455.