Cantilever Snap-Fit Performance Analysis for Haptic Evaluation

This paper investigates the parametric effects, which include material properties, hook shape, and shear deformation, on the force/deflection relationship governing the assembly/disassembly processes of a snap-fit for developing embedded algebraic solutions to achieve realistic force feedback through a haptic device. For this purpose, an algebraic model, which isolates individual parametric factors that contribute to the cantilever hook deflection, has been derived for examining assumptions commonly made to simplify models for design optimization and real-time control. The algebraic model has been verified by comparing computed results against those simulated using ANSYS FEA workbench and published approximate solutions. Additionally, the model has been validated by comparing the friction coefficients of three different snap-fit designs (with same materials), which closely agree within 5% of their root-mean-square value. Implemented on a commercial PHANTOM haptic device, we demonstrate the effectiveness of the model as embedded algebraic solutions for haptic rendering in design. Nine individuals participated in evaluating a set of design options with different parameter settings; 78% of whom chose the optimal theoretical solution by feeling the feedback force. These findings demonstrate that the design confidence of assembly robustness can be enhanced through a relatively accurate virtual force feedback.