Modelling, simulation and cost estimation of a conceptual bogie axle replacement

Sammanfattning: The forest industry in Sweden covers 28 million hectare as productive woodland. The soil is important for the forests ecosystem and the soils performance is decreased with increased soil compaction. In order to reduce the impact on the soil done by forest machinery a conceptual suspension axle is presented with the purpose to replace traditional bogie axle system on the trolley part on forwarders. This thesis goal is to determine if the proposed suspension concept isaviableoptionintheforestryindustryintermsofstrengthanddurabilityoftheconstruction and manufacturing cost. The project focus primary on suspension and will not focus on the overall design of the trolley.Amodelisdevelopedwhichisbasedonaideaandmodelprototype. Thegoalofthemodelling is to achieve a construction that allows the suspension to be extended or intended while still beingabletoturnthewheels. Threedifferentloadscasesistested,astaticloadcasewherethree loads are applied to the simulation model, the second case is a fatigue analysis and the third case is a collision case analysis. Each load case is simulated at two different model cases, one with the suspension located at the center, the middle case, and one case with the suspension located at the end point, the extended case. Resulting in a total of six simulations for each design.The final suspension design have a total weight of 1140 kg of one suspension and fulfills the product specification on all but one points, the desirable turning radius. The static analysis showednocriticalpointforneithertheinitialdesignorthefinaldesigninneithertheintended or extended case, but showed higher stress levels when the model was simulated at the extended case. The fatigue results showed similar results between the initial and final design because of the critical points parts where not redesigned between the designs. The collision caseshowedsimilarcriticallyforcebetweenthedesigns,aforceofapproximately70kNand40 kN for the middle and extended case respectively is required to reach the yield strength when colliding with an object.The cost of producing one suspension is estimated to 45800 SEK and is calculated through the tool costing for designer (CFD), which estimates the manufacture cost at an early design phase. The material cost for the suspension is the largest expanse covering roughly 73% of the total cost. In order to conclude if the suspension generates lower soil compaction compared to traditional bogie axles, a experimentally test is the optimal procedure. To be able to conduct this kind of field test the model have to be further refined to be able to produce.Theworkconcludestheproposedsuspensionsystemwiththefinaldesign,intermsofstrength and durability of the construction and the estimated cost, is possible to function in the forestry industry with the restrictions used in this work.