Critical operating conditions for assemblies with parameter-dependent dimensions

This article deals with the analysis of tolerances for an assembly that is bound to meet some functional requirements over a specified range of operating parameters (e.g. temperature, pressure and speed). These can influence part dimensions due to physical effects such as thermal expansion, deformation and wear. When these influences are added to manufacturing errors, unacceptable values of functional requirements can occur under critical conditions on operating parameters. To avoid this, a designer should be able to readily evaluate the operating window allowed to the assembly by a given set of tolerance specifications. A method is proposed to help this task on the assumption that requirements are verified through worst-case linear chains of dimensional tolerances.