• Rasmus Kokholm Pedersen
  • Mathias Sonsby Mouridsen
4. semester, Idrætsteknologi (cand.scient.techn), Kandidat (Kandidatuddannelse)
Purpose: This study determined the forces acting on a handbike, using strain gauges, in three field test scenarios
- accelerating, braking and road irregularities. In addition an initial optimization study was conducted using
the determined acceleration forces.
Methods: Free Body Diagrams and Finite Element Analysis (FEA) was used to determine strain gauge positions.
Laboratory calibrations were carried out to transform the measured strains into forces. One healthy male subject
performed five trials of each field test scenario – all out acceleration for three pedal cycles, braking the handbike
from a velocity of 41.7±0.3 km/h and riding across wooden list, simulating a cobblestone road (velocity of
37.3±1.1 km/h). A FE-model of the handbike, used for optimization, was validated by carrying out a calibration
study for each field test scenario. Lastly, an initial optimization study, in regard to frame stiffness, was conducted
by applying the acceleration force, calculated with the laboratory calibration, to the FE-model of the handbike.
Results: For the acceleration scenario the tangential and radial force peaks were 407.6 N and 380.0 N, respectively,
the peak brake force was 1571.1 N and the peak forces caused by road irregularities, were 12952.4 N and
21586.7 N, at the front and rear wheel, respectively, calculated with the laboratory calibrations. The tangential
and radial force peaks were 25.2 percent higher and 8.4 percent lower, respectively, while the peak brake and
road irregularity forces, at the front wheel, were 96.4 and 1328.3 percent higher, respectively, calculated with the
laboratory calibrations compared to the SW calibrations. The lowest displacement of the crankbox, 0.494mm, was
found by thickening the front V-tube of the FE-model.
Conclusion: The acceleration forces found was considered slightly overestimated and the brake force was considered
valid, while the road irregularity forces was not. As disagreement between the results of the FE-model
and laboratory calibration were present, the FE-model cannot fully be trusted for FEA, especially in regard to
brake and road irregularity force. The initial optimization study revealed that the highest stiffness by least weight
increase was obtained by thickening the frontal V-tube.
Udgivelsesdato2 jun. 2016
Antal sider76
ID: 234621802