Load measurement and analysis of kick scooters

Thesis

Kick scooters are rapidly growing in popularity as a form of transport and are used recreationally. They are also seen as an effective way to combat inner-city pollution. This project is (to the author’s knowledge) the first published work that aims to investigate the loads applied to scooters in real-world use. A data logging system has been built that is able to handle the vibrations associated with stunt scooter riding. The system can measure up to eight channels of strain data and log data up to a frequency of 62.5 kHz. A static force reconstruction model has been made for the scooter to gauge the magnitude of the applied loading to the scooter. Strain data is measured in the deck and the down tube of the scooter. Experimental results match well with finite element simulations. In addition, another force reconstruction model is made that considers dynamic effects. Results for measured strain and reconstructed forces for more than 25 of the following 12 different scooter stunts are given: bunnyhops, j-hops, tailwhips, heelwhips, barspins, opposite barspins, backside 180s, backside half-cabs, frontside 180s, frontside half-cabs, backside 360s and frontside 360s. Results show a significant variation in measured strains both within and between different scooter stunts. Regular barspins gave rise to the highest mean peak strains in the deck and down tube. Some of the peak strains do not appear to follow a normal distribution, as they fail the Shapiro-Wilk test for normality. Finally, a brief sketch is given of how the information could be used to optimise scooter components using topology optimisation. Results from a preliminary topology optimisation study are not successful in reducing the peak stresses in the neck of the scooter deck, highlighting the care needed in optimal scooter design.

Authors: Pearson, S

• DOI: 10.5287/ora-ngngqp8ee
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Keywords: force reconstruction; strain measurement; kick scooter
• Subjects: Dynamic testing; Force reconstruction; Mechanical engineering