Development of Analytical Model of Cantilever Hook Performance

With an increase in the use of polymeric materials in commercial products, snap-fits are attracting increased attention as alternatives to other, more traditional, joining methods. The field of snap-fit design is receiving greater attention as an engineering and research activity. Research in this area has focused on the development of performance models for individual features and heuristics for the design of snap-fit assemblies. An improved analytical model for cantilever hook snap-fit features is developed in this study. The modeling approach is a significant improvement over currently available analytical design equations. The model captures the effect of a snap-fit’s catch in causing contact forces to be offset from the beam’s neutral axis. Beam rotation, influence of axial force, and moment components on beam deformation are also incorporated by formulating a set of equations that model the system in its deformed configuration. The equation system is iteratively solved for several such configurations to model insertion and retention processes for snap-fits. The axial force component, which has been hitherto ignored in analytical design equations, is found to have significant effect on predicted snap-fit performance. The design space of cantilever hook features is explored by varying input design parameters. The model shows excellent agreement with experimental results, especially for low and medium retention angle snap-fit features. However, for high retention angle snap-fits, more accurate governing equations are required. Suggestions for possible improvements and future research directions are provided.