| The shortage of resources and environmental pollution problems has become increasingly serious with the development of national economy and automotive industry.New energy vehicles have attracted much attention for their advantages of energy-saving and environmental protection,especially for pure electric car.Lightweight design of automotive has been a research hotspot since it has a great advantage in improving recharge mileage and reducing energy consumption.Generally,new material is one of the important ways to realize automotive lightweight.Continues fiber reinforced composite materials have been widely applied in automotive components due to their good mechanical properties and great potential for weight reduction.Battery pack plays an important role in protecting battery cells and the lightweight design of battery pack is an important way to improve recharge mileage and reduce energy consumption of electric car.In this paper,the research of continuous glass fiber reinforced polypropylene(CGFRP)for application in battery pack was performed using experimental study and numerical simulation method.The main research contents of this thesis are as follows.Firstly,CGFRP was manufactured using mold process and quasi-static uniaxial tensile test and drop-weight impact test were performed to obtain mechanical properties of CGFRP.Damage characterization of the two fractured samples was studied by the macro-scale and micro-scale method to study the failure mechanism under different load condition.Research indicated that the damage type of CGFRP under tension and impact load were glass fiber fracture and delamination damage.Moreover,full-field strain response and damage evolution process of quasi-static uniaxial tensile test was characterized with digital image correlation(DIC)method.The results indicated that strain distribution was relatively uniform than metallic materials and concentrated load did not appear with the increase of uniaxial tensile load.Then simulation of quasi-static uniaxial tensile test and drop-weight impact test was performed to obtain CGFRP material constitutive parameters.The inversed parameters can be used in the subsequent analysis.Secondly,basing on the general principles and requirements,CGFRP battery pack was designed and analyzed with considering the function of all parts and structure formability requirements.The response of two typical conditions was analyzed based the established numerical model.Moreover,modal analysis was performed to avoid resonance of the designed CGFRP battery pack.Natural frequencies and modes of CGFRP battery pack had been obtained with calculated modes method and also the designed CGFRP battery pack satisfied the requirements of static analysis and modal analysis.Finally,considering the actual working conditions,the impact damage of CGFRP battery pack caused by road debris with different geometry parameters was studied.So a comprehensive parametric(radius and semi-apex angle of impacting punch)study of punch was performed to systematically analyze the impact response.The results shown that given different radiuses of punching tip with same semi-apex angle,punching tip with larger radius might affect a relatively larger number of battery cells and given the same radiuses of punching tip but different semi-apex angle,punching tip with larger semi-apex angle may affect a relatively larger number of battery cells.Also reuslts indicated that the influence of the final fracture pattern caused by semi-apex angle was also greater than that caused by radius.This study has a significant effect for analyzing battery pack and studying the influence of the geometric parameters of impacting punch tip on battery pack,and for fiber enhanced composite material application in automobile as well. |
PDF Full Text Request