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In tolerance analysis, the effect of clearance fits is especially difficult to estimate because the mating parts are not necessarily in actual contact and can take an infinite number of relative positions. The treatment of these situations is allowed in most of the available methods, possibly introducing additional elements in the dimension chains with appropriate statistical assumptions. The paper provides a similar extension for the static analogy, a previously proposed method that converts the tolerance analysis problem into an equivalent problem of force analysis. The procedure represents each fit, possibly between patterns of features (e.g., fasteners and holes), with a proper constraint in the equivalent static model. The ability of the constraint to transmit forces and torques is determined according to the types and directions of misalignments allowed by the joint clearance. With simple rules, this avoids complications in the static model, which must include only the constraint between parts rather than the geometric details of the mating features. The extended method, currently limited to 2D dimension chains, is demonstrated on examples involving both dimensional and geometric tolerances. The comparison with existing methods shows the correctness of the proposed procedure. The simplicity of the workflow confirms the possibility, already demonstrated for the static analogy, of avoiding numerical simulations or even the use of computer-based tools. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]