EVOLUTIONARY OPTIMIZATION OF GEOMETRIC TOLERANCES FOR COMPLIANT ASSEMBLIES WITH CONTACT INTERACTIONS

Geometric Dimensioning and Tolerancing (GD and T) is an important activity during product development phase, since it directly influences the manufacturing cost and subsequent manufacturing time. Traditional GD and T design methodology assumes that the complete assembly is perfectly rigid; hence it often leads to costly reworks and rejections. This increases the product development time and cost, also it forces the entire assembly to accommodate major Engineering Changes (EC) in order to meet the product functionality. This paper proposes an ideal alternative methodology to overcome the effects of the assumptions. Initially contact interactions in the assembly are simulated by Finite Element Analysis (FEA), since the mechanical contact influences severe nonlinearities, which makes the assembly compliant and non-ideal. The simulated compliant assembly is modeled using three dimensional degrees of freedom approach and an optimization problem is framed with an objective function of minimizing the manufacturing cost. Assembly function constraints, machining constraints and tolerance zone constraints are considered to solve the problem using Genetic Algorithm (GA). Finally an industrial example is chosen to illustrate the highly structured methodology.