Experimental Investigation of Bicycle Frame FEA Models

Abstract

This study experimentally investigated pedal cycle frame loads and verified analytical load cases applied to vehicle design. The experimental results were compared with a Finite Element Analysis (FEA) model. The weight of the rider on the seat, road induced loads and vibrations, and the force the rider exerts on the pedals affect the stress state of the frame. Strain gauges were applied to two different frame models. Four different locations were tested on a monotube long-wheel base (LWB) recumbent frame and six locations on a standard upright Schwinn. The stress state was calculated from the raw strain data. Depending on the gauge being used, the results either indicated the von Mises stress or simply the axial stress. The different loading conditions tested were as follows: static, steady pedaling on smooth, mid-grade, and rough pavement, and hard acceleration on level ground and uphill. The static and hard acceleration cases were directly compared to the FEA model. The experimental results were comparable to the FEA analysis. The complexity of the load case, coupled with unknown actual loads, explains the larger differences between FEA and experimental results. Based on experimental results, the FEA model was refined, improving the agreement between model and experiment. The stress states of a bicycle frame were successfully found experimentally, being confirmed by multiple runs under each loading condition. Based on the agreement between the two methods, the use of FEA load cases to predict stresses in pedal cycle frames was verified.