SUBJECT: M.S. Thesis Presentation
BY: Jason Nguyen
TIME: Thursday, May 31, 2012, 11:00 a.m.
PLACE: MARC Building, 201
TITLE: A Heuristic Optimization Method for the Design of Meso-Scale Truss Structure for Complex-Shaped Parts
COMMITTEE: Dr. David W. Rosen, Chair (ME)
Dr. Christiaan Paredis (ME)
Dr. Seung-Kyum Choi (ME)


Additive manufacturing can be used to produce a vast array of structures, some of which would be impossible to manufacture using traditional manufacturing processes. One application of this technology is for fabrication of customized, light-weight material called meso-scale lattice structures (MSLS). MSLS are a type of cellular structure with strut diameters in the range of 0.1 to 10 mm and strut length on the order of centimeters. They are suitable for any weight-critical applications, particularly in industries where both low weight and high strength are desired. MSLS can easily have hundreds to thousands of individual strut, where the diameter of each strut can be treated as a design variable. Since the computational complexity of the design problem often scales exponentially with the number of design variables, topological optimization that requires multi-variable optimization algorithm is infeasible for large-scale problems. In previous research, a new method was presented for efficiently optimizing MSLS by utilizing a heuristic that reduces the multivariable optimization problem to a problem of only two variables. The method is called the Size Matching and Scaling (SMS) method, which combines solid-body analysis and predefined unit-cell library to generate the topology of the structure. However, the method lacks a systematic methodology to generate the initial ground geometry for the design process, which limits the previous implementations of the SMS method to only simple, axis-aligned structures. In this research, an augmented SMS method is presented. The augmented method includes the integration of free-mesh approach in generating the initial ground geometry. The software that embodies that ground geometry generation process is integrated to commercial CAD system that allows designer to set lattice size parameters through graphical user interface. In this thesis, the augmented method and the unit-cell library are applied to various design examples.