Design of Eccentric Double Amplitude Vibration Drum Roller Shaft with Improved Mass Moment of Inertia : Product Development of Compaction Equipment

Sammanfattning: Road construction is important to make transports safe and sustainable. To compact asphalt an amount of energy needs to be conducted into the material either by static pressure or dynamic vibrations. An asphalt-roller compact the material and increases its load-bearing capacity. An eccentric shaft that generates vibrations is attached inside the roller drums. The shaft has two modes, varying between high eccentricity with slower pulses and low eccentricity with faster pulses. The study has been performed with the purpose to decrease the mass moment of inertia by redesigning the present eccentric shaft and verifying the new concepts with linear and non-linear FEM simulations. The new models were to have the same functional properties as the present eccentric shaft.  The current cross-section of the shaft was changed to a cross-section of a circle in the periphery. This was done by adding all features in new geometry to a simple shaft base and creating an analysis chain. To create the new lengthwise design brainstorming was used to generate ideas. The ideas were then sorted by using a Pugh matrix. CAD was used to model the concepts with the desired eccentric properties. Simulation in FEM software was used to acquire information about the behaviors during operation. Academic validation and useful information have been gathered by doing a literature review.  Two resulting concepts with properties fulfilling the prevailing restrictions. The circular cross-section in the periphery was adapted and the eccentric properties were kept. The simulation results from FEM software ended satisfactorily within limits for both execution in steel and ductile iron. For both concepts the mass moment of inertia was minimized, with 40.5 % in steel and in ductile iron with 42.0 % and 42.6 %.  An analysis chain has been performed showing that a cross-section with a circular geometry is optimal when the intention is to minimize the mass moment of inertia. It is possible to minimize the mass moment of inertia without negatively affecting the eccentric properties. The lengthwise design of a shaft with eccentric properties has been studied and simulated. Two concepts with varied lengthwise designs have been created with conserved eccentric properties and significantly decreased mass moment of inertia. The concepts can compose a good basis to continue investigating the lengthwise design which hopefully ends in a manufacturable eccentric shaft that contributes to environmental asphalt construction with low energy usage.