Investigation On The Dynamic Characteristics And Constitutive Model Of Polycarbonate Of Aircraft

As one of the polymeric glassy materials, PC, short for Polycarbonate, is widely used inthe field of national defense and engineering application, such as windshield of aircraft andautomobile, helmet and body amour, etc., because of its excellent heat and impact resistance.It is well-known that polymer materials are very sensitive to the temperature and strain rate,which means their property would be different as the change of rate and temperature.Therefore, it is very important to study their mechanical behaviors. In this paper, the dynamiccharacteristics and constitutive model of the Polycarbonate, especially applied for windshieldof aircraft, are studied experimentally and theoretically. The work can be mainly divided intofour parts as following:The first part (chapter2): Through the MTS compression facility and the SHPB，shortfor Split Hopkinson Pressure Bar, the curves of PC true stress-strain behavior in uniaxialcompression were obtained, at temperature ranging from-40℃to100℃and rates rangingfrom0.001s-1-5000s-1. It is clear that character of PC is rate and temperature-dependent.The second part (chapter3): Based on the PC experiment at room temperature, we usethe Piecewise Linear Plasticity model in LS-DYNA3D to describe the PC and then do theSHPB simulation to make the verification on the experiment. Furthermore, the Johnson-Cook（J-C）model is proposed for PC and employed in the simulation on bird impact windshield ofaircraft. The good match between the numerical and experimental results shows theavailability of PC J-C model in engineering application.The third part (chapter4): Based upon on DMA data and combined with the visco-elasticand visco-plastic theory and time temperature equivalence principle on polymer material, thenew visco-elastic and visco-plastic constitutive model is established for PC. The materialparameters are almost determined directly via the experiment instead of numerical fitting. Themodel prediction and test data get an excellent match.The fourth part (chapter5): The investigation is made on the experiment that PC plate isstruck by soft body. The time history curves of displacement strain are obtained by thedisplacement sensor and strain gage. The high speed camera is used to catch the largedeformation and cracking behavior occurring on PC plate.