Aluminum Alloy Frame Design For Light Duty Truck

As the demand for urban and rural transportation business increases,the light-duty truck plays an important role with its convenient and efficient transportation capacity.In order to solve the problem of "large weight with small labels" of light-duty trucks,the Ministry of Industry and Information Technology and the Ministry of Public Security jointly issue the "Notice of the Two Ministries on Further Strengthening the Production and Registration Management of Light Goods Vehicles and Small and Micro Passenger Cars",which strictly regulates the total mass and other parameters of light-duty trucks.Therefore,light weight research on the light-duty truck can effectively improve the competitiveness of the industry.In this paper,the steel frame of a light-duty truck was replaced by a lighter aluminum alloy frame as the direction of lightweighting.Taking the steel frame of the light-duty truck of a certain enterprise as the research object,the dynamic characteristics,stiffness and strength analysis were carried out,which led to the establishment of the frame’s performance standard.The designed aluminum alloy frame,whose optimal material distribution form was obtained by topology optimization,was analyzed under the same conditions as the original steel frame and compared with the performance standards.The result was a lighter and more powerful aluminum frame.Specific research contents include the following:Firstly,the performance standard was established based on the analysis of the original steel frame.According to the basic finite element theory,the original steel frame was discretized in Hyper Mesh.The finite element model was established,which was used to analyze and calculate the free modal,bending stiffness and torsional stiffness.The performance standards of the frame were established based on the analysis results and actual requirements.Secondly,the strength analysis of the original steel frame was carried out by the inertia release method.The front and rear leaf spring suspension models were built by multi-body dynamics software ADAMS/CAR to extract the loads of the suspension system on the frame under typical working conditions,which assisted in improving the accuracy of the strength analysis of the frame.The loads were applied together with the loads of the bearing parts of the frame in the finite element software to carry out the strength analysis of the original steel frame under various working conditions.There is an unconstrained problem that the frame was simultaneously subjected to the load from the suspension system and its bearing parts in the software,so that the inertia release method was used to simulate its working state for its statics analysis.Thirdly,the topology optimization design of the new frame was carried out.A finite element model of the design area was founded to find the optimal material distribution form of the aluminum alloy frame.The upper limit of the volume fraction was constrained,and the minimum weighted compliance under each working condition was taken as the objective function for topology optimization.Since the frame should deal with different frequency of various working conditions during working time,the exponential scale analytic hierarchy process was used to calculate the weight value of each working condition qualitatively and quantitatively.The weight of each working condition was input in the topology optimization process,and the aluminum alloy frame was designed according to the topology optimization results and actual requirements.Finally,the performance analysis of the designed aluminum alloy frame was the same as that of the original steel frame,and the analysis results were compared with the performance standards,and the strength check was carried out under each working condition.The aluminum frame was discretized in Hyper Mesh to obtain its finite element model,and the dynamic characteristic,bending stiffness and torsional stiffness of the aluminum frame were calculated.The strength of the aluminum alloy frame under typical working conditions was checked by using the same boundary conditions as the original steel frame.According to the analysis results,the dynamic characteristics,bending stiffness and torsional stiffness of the aluminum frame were improved compared with that of the original steel frame,and the strength under all working conditions met the requirements.The mass size was reduced by 30.8% compared with the original steel frame,which meant that the lightweight effect is remarkable.