Optimizing the Structural Finite Element Method based Process to Evaluate the Sustainable Human Accidental Sliding Load of Automobile Airvent Knob Design Made with Thermoplastic PC - ABS

The research work elaborated the structural integrity of airvent by skipping the assembly level snap fit finite element analysis of knob to reduce computational complexity of air vent knob sliding test post stopper. During assembly, the strain based mechanical breakage prediction of airvent sliding knob snaps is investigated in non-prestressed condition.

The research work proposes a FEM based analysis approach to evaluate the mechanical breakage load of airvent knob assembly for accidental sliding load. This process skips the assembly level snap insertion load case along with silicone rubber pad compression which could serve as the prerequisite simulation. This prerequisite simulation is computationally expensive and complex to solve due to polymer plasticity and silicone rubber elastomer hyper-elasticity and moving frictional contacts between parts. If the accidental sliding load case without considering pre-tension on snaps is simulated, the load causing mechanical failure in the FEM based analysis is not correlating with experimental prototype samples breakage force values. The strain at break for composite, polycarbonate (PC) with acrylonitrile-butadiene-styrene (ABS) material used for knobs, is 100%. By considering the lower strain criteria of 5%, the analysis results and experimental testing results in terms of load causing mechanical breakage and breakage zones are co-related. To validate the established breakage strain criteria of 5%, another airvent knob design with same material of knob is considered for study. A good correlation is established between FEM approach and experimental testing. It is concluded from the outcomes of the FEM based analysis that the 5% strain as breakage criteria set for capturing knob strength for accidental sliding load case is efficient. The same process set can be utilized for developing more airvent knobs