Date of Award

Spring 2001

Document Type


Degree Name

Doctor of Philosophy (PhD)


Mechanical & Aerospace Engineering


Mechanical Engineering

Committee Director

Gene Hou

Committee Member

Chuh Mei

Committee Member

Sebastian Bawab

Committee Member

Stephen Cupschalk


It is quite common in the industry to use various interface methods, such as welding, fasteners, bolts, adhesive bonding, etc., to join substructures together. The quality of the assembled structure is directly related to the type of the interface methods used in the manufacturing process. Thus, it is important to include the interface conditions as part of design variables in any design process. To this end, this work develops a reanalysis method that can efficiently analyze structures with variations on the interface conditions. This reanalysis method is based upon a new two-step substructuring technique. The first step performs substructural level analyses for each of the isolated substructures. Any commercially rated structural analysis code is allowed to be used in this step. The results of the first step are then used to form a reduced order matrix equation in terms of the interface reactions. Once the interface reactions are calculated, the displacements and stresses in each of the substructure can be conveniently calculated. In this proposed method, only the reduced order matrix equation in Step 2 is required to be resolved for structures with different interface conditions.

The first pail of the work will discuss the derivation and implementation aspects of the substructuring technique. Later, the technique is used to support a simple genetic algorithm for placement design optimization of spot welds. Assessment of the proposed method via numerical study is summarized at the end of the dissertation.


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