Study On Preparation And Mechanical Properties Of Ice

With the progress and development of society,aircraft has increasingly become the preferred means of transportation for people to travel,meanwhile,carbon fiber reinforced composite?CFRP?has been widely used in the manufacturing process to make the aircraft bigger and lighter in order to maximize its loading capacity.However,aircraft are sometimes vulnerable to hail impact during take-off and landing,and the performance of CFRP will be seriously degraded under external impact,such as hail,which endangers the lives of passengers and crew seriously.In this paper,in order to understand the relationship between hail and aircraft in the process of impact and provide the relevant data for the design of aircraft in the future,the mechanical properties of hail have been investigated by experimental ice making method.Therefore,in order to clarify the influence of the freezing temperature and the cotton wool content on the mechanical property,the damage form and the energy change of the ice dynamic compression,by adding a different proportion of the cotton wool in the deionized distilled water and reasonably controlling the freezing temperature to prepare the-10°C,Test pieces of 0%,0.3% and 0.5%,respectively,at the freezing temperature of-20°C and-30°C.The dynamic compression experiment of ice specimen under different loading conditions was carried out by using the split Hopkinson pressure bar?SHPB?and combined with the high-speed camera,and the numerical simulation of the experiment under the same working condition was carried out by using the finite element software LS_DYNA.to The conclusions are as follows:Under the same freezing temperature,the strength limit of different test pieces containing the cotton is continuously increased with the increase of the speed of the impact rod;the test piece containing the same cotton quantity is continuously enhanced with the decrease of the freezing temperature and the resistance of the test piece to be damaged;and when the speed of the impact rod is low,When the velocity of the impact rod is increasing,the test piece starts to crack and the dislocation movesalong the crack,and the test piece has obvious plastic deformation or even damage;The incident energy,reflection energy and dissipation energy of different test pieces with the same freezing temperature are positively correlated with the speed of the impact bar;loading After the test piece is completed,the reflection energy is less than the transmission energy when the shape of the test piece is high,and the reflection energy is larger than the transmission energy when the test piece is seriously damaged.The finite element software LS_DYNA is used to simulate the experiment under the same working condition,and when the loading condition is not enough to cause serious damage to the test piece,The results obtained by using the Lagrange method and the MAT₁0 material model are obviously superior to the results obtained by using the SPH algorithm and calculated with the MAT₁55 material model,but there is no significant difference between the shape characteristics of the test piece during the test piece loading process,and when the loading condition is enough to cause serious damage to the test piece,the Lagrange algorithm is used to simulate the test piece,The morphological characteristics of the specimen will no longer be suitable because of the serious distortion of the grid,while the morphological simulation obtained by the SPH algorithm is in good agreement with the real experimental results,but the simulation results of the mechanical properties of the specimen Lagrange algorithm is still more accurate than the SPH algorithm.