883. Curtailment of Mass Property Measurements Due to Tolerance and Regression Analysis

Paper

Abstract

This paper describes a method of curtailing measurements of mass, center of gravity, moment of inertia, and product of inertia. The method yields at least two benefits. Before production, optimum selection of materials and tolerances is possible consistent with established mass property limits. During the production phase mass property measurements are curtailed, and possibly omitted if deemed appropriate.
In the pre-production design phase, measurements cannot be performed . However it is shown with a chosen degree of confidence that established mass property limits will not be exceeded. This is possible by using tolerance analysis coupled with a Monte Carlo Creation of a sample production run of components, and regression analysis.
Subsequently, in production, complete measured mass properties normally can be limited to the first twelve components if deemed appropriate. Regression analysis curves can be generated by use of the measured data. Comparison with pre-production data can be made. Subsequent production measurements of only mass and center of gravity can be performed on a limited spotcheck basis. Associated moment of inertia and product of inertia limits are available from the regression curves. The curtailed.measurement scheme can be statistically monitored to detect any undesirable trends.
A sample model configuration is analyzed by the Direct Approach Concept (DAC) and twelve models are assembled by Random Assembly Method (RAM).