Tolerance Allocation for Structures Subject to Various Loading Events

Although allocation of design tolerances for parts and components is typically based on the prediction of geometric and dimensional deviations resulting by the inherent errors of production, this process cannot be conducted unconstrained. Concurrent to studying the manufacturing and assembly uncertainties in tolerance allocation, it is highly important to evaluate the total combination of the allocated tolerances and the deformations due to various loading on the final product. This ensures that parts and components in their working condition meet their essential requirements for functionality, form and fit. This process is optimized only if the minimum geometric zone that covers the evaluated deformations is studied properly. In addition, the minimum deformation zones for various types of loading in an assembly of parts and components need to be studied and the tolerances should be selected after considering the requirements for all possible events. Using this concept, a unified methodology is developed to find the optimum tolerances for the geometric parameters of mechanical structures which are under various loading condition. Validity of the developed procedure is studied by conducting case studies and variety of experiments. The developed methodology can be employed efficiently during detailed design process of mechanical parts and assemblies.