Structure And Crash Analysis Of Glass Fiber Reinforced Instrument Panel Considering Fiber Orientations

As the world’s automotive industry facing a series of problems, such asenergy shortages, environmental pollution, and so on, reduce the weight of thecar is an important direction of development. Automotive body and various carparts made by glass fiber reinforced composites show the advantage of lightweight, good corrosion resistance and low noise. Fiber orientation anddistribution are the main factors affecting the mechanical properties of fiberreinforced composites. The injection molded parts show anisotropic mechanicalproperties, for the axial tensile properties of fibers and the uncertainty ofdistribution in the parts. The existing simulation process endow isotropicmaterial model for it (DYNA24#), but the results are not precise enough. So it isvery important to take the distribution of fiber direction into account to enhancethe accuracy of the finite element analysis.This paper takes glass fiber reinforced car instrument panel as the object ofresearch. By introducing fiber orientation tensor, the average distribution offibers in the glass fiber reinforced PP resin composite is acquired throughinjection molding simulation with MOLDFLOW. Test samples are cut from theinstrument panel with an angle of0°,45°,90°to the fiber direction at theposition where fibers are highly aligned. The tensile moduli are obtainedthrough tensile tests. Quantitative fiber distribution and orientation alongthickness at specific spots are obtained by metallographic method proposed bythis paper. Though the contrast of angle between the sample axially direction and the first main direction of average fiber orientation and the tensile moduli,considering the main value of eigenvalue, it is concluded that using averagefiber direction take the place of the directional distribution of the elasticmodulus is reliable.The relationship between element ID、node ID and average fiber orientationID is realized by MATLAB program proposed by myself. The program readsmesh model of DYNA analysis and mesh model of MOLDFLOW analysis, andthe corresponding relationship is found out between them by finding the nearestMOLDFLOW analysis model element to every DYNA analysis element. Andthen the fiber direction information is transmitted to the element of structureanalysis. Ultimately, the keyword with material card is written by binary filewhich can read by DYNA software.Take the tensile modulus as material parameter and the structure meshcontaining directional information produced by MATLAB program as elementinformation, the boundary condition is given according to the test. The result ofstructure simulation is contrasted with the result of test. Through thecomparative analysis of simulation results of orthotropic material model withisotropic material model with the actual results of the experiment, it isconcluded that orthotropic material model not only can consider the mechanicalproperties of the material itself, but also the results are closer to the actualexperimental results. So the orthotropic material model is a better materialmodel for fiber reinforced material. Through head crash analysis betweendifferent material models, it can further illustrate the superiority of theorthotropic material modelAt last, the main research work and innovations are summarized togetherwith some of the inadequacies of the thesis are pointed out, and then furtherresearch outlook is proposed.