Research On Optimal Design Of Body-in-white Transportation Packaging Based On Modal Analysis And Passive Vibration Isolation

With the development of the automobile industry and international trade,the bulk packaging of automobile products has gradually attracted the attention of automobile manufacturers and the packaging industry.The body-in-white package is a large-scale transportation package.Due to its large volume and weight,the test design has high cost and long cycle.Its design is mainly based on empirical design,lacking a reasonable design plan.This subject takes a car body-in-white as the research object,and carries out the work of body-in-white modeling simulation analysis and modal analysis,optimization design of body-in-white packaging based on passive vibration isolation theory,and simulation analysis of body-in-white package drop.Using HyperWorks to carry out finite element modeling of body-in-white,complete modal simulation analysis and vibration test modal analysis,the correct body model is obtained,which lays the foundation for the optimization design of body-inwhite packaging simulation.Analysis of the modal vibration modes of the car body reveals that the structural nodes of the front longitudinal beam and the rear crossbeam of the chassis can be used as packaging load-bearing and restraining parts,which provides a basis for the packaging structure design.The container selection was completed,combined with the modal vibration mode nodes of the car body,a steel-wood combined frame-type body-in-white packaging structure was designed.Static analysis was carried out to verify the strength of the bearing structure under static conditions.Through modal analysis,the modal parameters of the body packaging are obtained,whose fundamental frequency is 3.78 Hz.Combining passive vibration isolation theory and road spectrum excitation curve,it is found that the package is prone to resonance and friction and wear in the peak frequency range of the road spectrum,and vibration isolation optimization is required.A steel-plastic composite packaging vibration isolation scheme is proposed.Based on the passive vibration isolation theory,the frequency ratio of the road spectrum excitation signal to the package fundamental frequency is obtained through modal analysis,and the design of the thickness of the vibration isolation pad and the size of the sleepers is completed.Through random vibration simulation,the ratio of the acceleration amplitude of the product to the acceleration amplitude at the bottom of the product package,that is,the vibration isolation rate,is obtained to complete the vibration isolation optimization.The final decision was to use 10 mm thick EVA liner with 33% VA content and corresponding size sleepers to isolate the body-in-white package.This method improves the vibration isolation effect,reduces the friction and wear between the body and the packaging structure,avoids excessive packaging of products,and provides a reference for the optimal design of packaging vibration isolation.In the process of loading and unloading,the package may suffer from the impact of a drop and cause structural damage and other insufficient strength problems.In this project,the LS-DYNA software was used to simulate the surface drop,edge drop and angle drop of the load-bearing structure.Improve the insufficient strength and structural damage in the simulation results to meet the impact protection requirements.