Lightweight Design Of Heavy Duty Truck’s Frame Based On Stiffness And Modal

Along with the rapid development of the automobile industry, environmentalpollution problems and tense energy issues become increasingly serious. Heavy dutytrucks which are widely used in transportation industry play an important role in thenational economy. Due to rectification of the overloading problems in recent years,load capacity of heavy duty trucks reduces a lot. All of that put forward higherrequirements for lightweight of automobile to reduce vehicle quality and increase loadcapacity. As important bearing parts frame of a heavy duty truck, frame lightweight isan effective measure to improve automobile fuel economy; it plays an important rolein modern automotive design. Under the premise that guaranteeing basic performanceof frame make it lightweight as far as possible, which is great significance forenterprise in lowering the design and manufacture cost, and strengthening marketcompetition.An optimization method based on stiffness and modal is proposed to the frame byconsidering multiple loading conditions which include bending stiffness, torsionalstiffness and first order modal in this paper. Considering bending stiffness, torsionalstiffness and first order modal, lightweight design of frame is achieved by optimizingthe thickness of frame parts. First frame finite element model is established in thefinite element software, based on which the strength of frame is calculated andchecked on four conditions. Static and dynamic electronic experimentation based onvirtual instrument technology is conducted to the frame, reasonableness of the finiteelement model is verified by static full load tests, and checking the frame strength byanalysis the stress of frame on electronic experimentation strain test points.Stiffness and modal analysis is conducted to frame based on the verificationfinite element model, and bending stiffness and torsional stiffness values are obtained.The first10free modal of the frame are extracted by modal analysis. Naturalfrequencies and natural vibration type are used to investigate the dynamiccharacteristics of the frame. Based on the finite element model, acquired primaryfrequency, bending stiffness and torsional stiffness values as data support, thesensitivity for the frame parts thickness are analyzed to choose reasonable parts asoptimization objects.Uniform Latin Hypercube experimental design method is applied to obtain the design variables sample point of frame mass, bending stiffness, torsional stiffness andprimary frequency. Approximate equations of the model’s responses are built by usingradial basis functions approximate method. A vehicle frame lightweight designoptimization model was built with stiffness and primary frequency constrained.Genetic algorithm was used to optimize the passed error evaluation approximatemodel. The optimization result parameters were substituted into the real model; theresults showed that at the condition of meeting the requirements of stiffness andprimary frequency the frame total mass were decreased by18.37kg, optimizationresults of the approximate model compared with the finite element analysis resultsshow that the method is reliable and effective.