Date of Award

2008

Degree Type

Thesis

Department

Mechanical Engineering

First Advisor

Rashidi, Majid

Subject Headings

Machinery, Kinematics of, Tolerance (Engineering), kinematic, Tolerance, Mechanism, Skewness

Abstract

A kinematic based tolerance analysis of mechanisms is presented in this thesis. It is shown that standard kinematic analysis can be used for obtaining closed-form explicit formulations for tolerance analysis of mechanisms. It is proposed that the manufacturing tolerances are accounted for by incorporating fictitious sliding members in the rigid links, thereby allowing them to either "grow" or "shrink" along the lines of their pin connections. The virtual expansions or contractions of these fictitious sliders are captured in the kinematic equations by taking the differentials of the magnitudes of the vectors that define the length of rigid links having dimensional tolerances. These mathematical differentiations follow exactly the procedure of kinematic velocity analyses of mechanisms. The method can further be extended to perform tolerance analysis on a group of identical mechanisms. The tolerance analysis presented in this thesis was utilized to study tolerance accumulation in three (3) different mechanisms, slider crank, Scotch-Yoke, and a one-way clutch. In each case, the effect of tolerances in the individual components were combined together, through modified kinematic analyses, in order to determine the resulting accumulation of the tolerances in the assembly of the parts for any generalized configuration of the mechanisms. The analysis was further extended to include statistical skewness analyses on the tolerance distributions of the individual components and the resulting skewness on the assembly of the mechanism. The main benefit of the presented approach is its allowance for the use of standard kinematic computer codes for tolerance analyses of mechanisms

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