Konstruktion av fackverk och drivlina i ett navlöst hjul : Designprocess med jämförelse av metoder

Sammanfattning: This paper is a part of the course PPU305 at Mälardalen University, the bachelor thesis. A companycurrently developing an electric bicycle had a concept of an innovative wheel containing no spokesand no hub. This meant that the functions these components usually fill needed to be solved in anotherway. The method for this product development process has been a combination of the genericalmethod, design thinking and the method used at the company. While the author was planning onworking with the generical method but soon became aware of the completely different method by thecompany, a more flexible method was adapted.With this background, two research questions were formulated:RQ 1: How can the driveline be constructed to fit with the planned design in an electric bicyclewheel?RQ 2: How does the development process work for the electric bicycle and its wheel in the companyin question, compared to other product development processes?The result was a framework carefully designed to be made of as little material as possible but still bestrong enough. This framework has two sides and is what mainly holds up the construction and makesit resistant to dynamic loads. Material selected for this construction is carbon fibre due to its lowdensity and high tensile strength. This work includes every part of the bicycle’s wheel including theskeleton framework mentioned above and everything between the two walls. The author has selectedmotor, bearings and spur gears suitable for the vehicle and made mounts and necessary fixtures forall.To decide that the framework was designed as efficiently as possible, several simulations inSolidWorks Simulation were made where different designs were compared against each other. Everyadjustment in the designed were direct results of the simulations. Although the simulations cannotfully replace a physical test, it gives an idea of how well the construction reacts to loads. To makesure that the material selected would stand the loads as expected, the material in question was orderedfrom planned deliverer and tested in a tensile test machine. This gave more accurate data regardingthe material properties that data collected from Granta Edupack, a material database. About thedevelopment process at the company, it was discovered that it has both similarities and differences tothe generic product development process and Design thinking. The biggest difference with the bothprocesses was the short-termed planning. The process most similar with the one used at the companywas Design thinking since they both depend on agility and creative thinking with iterative processes.