Abstract: A method and apparatus for performing a gap stack-up analysis for a machine gap. The gap is defined by opposing faces of two machine parts. A vector loop is determined beginning at one of the opposing faces, traversing through the machine parts that affect the gap dimension and terminating on the other opposing face. The dimensions and the tolerances associated with each of the parts in the vector loop are combined to yield the gap dimension and the gap tolerance. In one embodiment the gap stack-up is determined by a computer program product for execution by a computer processor.

Abstract: A method for performing geometric dimension and tolerance stack-up analysis for an assembly, the method comprising receiving a target assembly dimension for stack-up analysis, where the assembly includes at least one part. The method further comprises receiving a feature corresponding to the part and receiving feature tolerance data associated with the feature. The feature tolerance data includes at least one of size tolerance and geometric tolerance. Stack-up rules are accessed in response to receiving the feature tolerance data. The stack-up rules include instructions to determine if a form tolerance, an orientation tolerance and a profile tolerance should be included in a stack-up tolerance for the feature. The stack-up rules also include formulas to calculate a nominal dimension and the stack-up tolerance for the feature when the feature tolerance data applies to features of sizes.

Abstract: A method for performing geometric dimension and tolerance stack-up analysis for an assembly, the method comprising receiving a target assembly dimension for stack-up analysis, where the assembly includes at least one part. The method further comprises receiving a feature corresponding to the part and receiving feature tolerance data associated with the feature. The feature tolerance data includes at least one of size tolerance and geometric tolerance. Stack-up rules are accessed in response to receiving the feature tolerance data. The stack-up rules include instructions to determine if a form tolerance, an orientation tolerance and a profile tolerance should be included in a stack-up tolerance for the feature. The stack-up rules also include formulas to calculate a nominal dimension and the stack-up tolerance for the feature when the feature tolerance data applies to features of sizes.

Abstract: An apparatus for characterizing a design function, the apparatus comprising: a first perturbation module adapted for writing a first perturbed input value into an input cell of an input spreadsheet to generate a first perturbed output value of an output cell of an output spreadsheet; and a sensitivity calculator adapted for calculating a design function sensitivity from the first perturbed input value and the first perturbed output value.