Research On Mechanical Properties And Lightweight Of Fiber-reinforced Injection Foam Parts Based On Multi-scale Joint Simulatio

Supercritical fluid injection foaming technology is a molding process developed on the traditional injection molding technology,it is favored by aviation,automobile manufacturing and other industries because this technology can reduce the quality of plastic parts.With the continuous development of composite materials,fiber reinforced materials are gradually applied to the production of foaming products.Simulation analysis is an important part in the process of product design,however,the traditional simulation loses its accuracy due to the introduction of bubbles and fibers in the injection molding of fiber reinforced materials.Moldex3d-digimat-abaqus multi-scale joint simulation can overcome the shortcomings of traditional simulation.Micro-information such as bubble hole and fiber orientation of plastic parts is obtained by Moldex3 D software.Digimat can mount the micro-information such as bubble hole and fiber orientation on the structure mesh used in Abaqus analysis.Then,finite element analysis software Abaqus can be used to complete the simulation analysis of the macromechanical properties of plastic parts,which also considers the relationship between process parameters,product micromorphology and mechanical properties,this is of great significance in product design stage.In this paper,the accuracy of multi-scale co-simulation is verified first,and then the influence of process parameters such as foaming agent content and melt temperature on the diameter and density of the bubbles is studied.Thirdly,taking bubble size,Young’s modulus and weight reduction ratios as response values,P-B experiment,full factor experiment and BB experiment in Response Surface Method were used to screen the key factors affecting the response value,determine the B-B experimental center,and predict the response value under random process parameter combination.Finally,taking the vehicle timing chain guidance board as the research object,the maximum stress value of the guidance board under the same pressure load was reduced through optimization methods such as wall thickness optimization and hole position optimization,and then the quality of the plastic parts was reduced based on the influence law of the obtained process parameters on the quality of the plastic parts,and finally the overall optimization design of the guidance board was completed.The main contents and conclusions of this paper are as follows:(1)The basic principle and process characteristics of injection molding foaming were introduced,and the injection molding foaming technology based on fiber reinforced materials was summarized.At the same time,the research status of injection molding foaming technology based on single-scale joint simulation and multi-scale joint simulation was briefly introduced.(2)The theoretical basis of injection molding and foaming joint simulation based on fiber reinforced materials is introduced.Meanwhile,standard tensile part is taken as the research model.After comparing the joint simulation results based on Moldflow and Moldex3 D with the actual results,it is found that the mold flow analysis results are basically consistent with the actual results.The mechanical results of 0°,45° and 90° mapping and co-simulation were different from the actual results to a certain extent,but the results of Moldex3 D in the elastic stage were in better agreement with the actual results.Therefore,Moldex3 D was selected as the modal flow analysis software and the accuracy and feasibility of the co-simulation was verified.(3)Taking the diameter and density of the foam as the standard,the single factor experiment was used to analyze the influence of the process parameters on the pure resin material.The results showed that increasing the content of blowing agents was beneficial to increase the cell density.With the increase of melt temperature,the pore size increases and the density decreases.The increase of mold temperature is beneficial to improve the size uniformity of bubble holes and increase the density of the bubble holes.The results of pressure holding time,filling time and cooling time show that the order of influence on the size of the bubble holes is pressure holding time > filling time > cooling time.(4)Based on the quality of foamed parts of fiber reinforced materials,the diameter of bubble holes and Young’s modulus as standards,through the P-B experiment determined that key factors affecting each standard are foaming agent content,fiber content and filling time.Then,take bubble diameters,Young’s modulus and weight reduction ratios as respond values,the effects of process parameters on the response values were analyzed by response surface method,and the results of foam plastic parts under random process parameters combination were predicted and compared.The results showed that the predicted results were in good agreement with the actual results,and the multiple regression equation had a good prediction effect.(5)Taking the automobile formal chain guidance board as the research model,the quality and maximum stress value of the guide plate as the standard,and the reduction of the quality and maximum stress value of the plastic part as optimization objectives,we first optimized from the wall thickness and the structure of guidance board,and then obtained two models with low maximum stress value,and finally reduced the quality of the model through the optimization of process parameters.At the same time using multi-scale joint simulation to verify the process parameters,maximum stress of the optimized model and compared with the original model results,the results show that the optimized model’s maximum stress value and weight is lower than the original model,it is given to illustrate the effectiveness of the optimization scheme.