Renewable Energy Research

Strain Gauge dynamic Measurements

Dynamic Strain Measurements in a Bicycle

The purpose of this thesis was to characterize a bicycle dynamically from point of view of its mechanical properties. The bicycle, with its many components, is subjected to a wide variety of stresses. The different components of the bicycle such as the crank shaft is subjected to relatively high bending and torsional stresses, other parts such as the down tube, the fork and the chain stay subjects to much lower tensile, compressive and torsional stresses. Therefore strain gage rosettes were installed on the down tube, the fork, the chain stay and pedal crank. The Delta rosette must be connected to three channels of the Traveller StrainMaster. This device measures the strains dynamically by the Analog to Digital Converter card. The measured strains in the pedal crank were up to 350 microstrain. The down tube designed to provide torsional rigidity during pedaling, experienced relatively low strain levels of 45 microstrains. The strains in the fork show faster periodic change (~1Hz). The strains were about 25 microstrains. The strainas in the chain tray were mainly compressive. The strains were about 65 microstrains. All parts of the bicycle were loaded within the elastic region. For future research strains could be measured along different positions of a frame tube to find the strain distribution along the frame tube. This information should help in frame design and material selection.