Buckling and Postbuckling of Elastomeric Components: Tactile Feel in Electric Switches

Abstract

Abstract Within the range of the parameters of the switch designs considered, only very slight cocking of the switch structure occurred. Thus, with minimal off-axis cocking, the axisymmetric assumption remained valid, resulting in a considerable finite-element economization when compared to a full three dimensional model. Some switch designs encounter localization problems, such as surface folding and stiffness mismatches. Mesh refinement is not a general panacea for these localization problems. Regardless, a fold of this type or stiffness mismatch is generally indicative of a potentially poor switch design, with the possibility of associated fatigue problems. For the switch designs considered, the peak strains were found to be less than 70 percent; thus the Mooney-Rivlin and Ogden material models yielded essentially similar results. Furthermore, a Hookean material model may be adequate for some purposes, because the tactile-feel response was found to be dominated more by switch geometry than anything else. Overall, we have seen that combining FE analysis together with the full continuum-constitutive-boundary formulation can successfully address the problem of buckling and postbuckling of elastomeric structures. In the case of switches, such behavior is an intrinsic property. This is an interesting contrast with traditional structures.