| The grillage structure is composed of flat plate and crisscross stiffeners.The appearance of longitudinal and transverse stiffeners leads to the grillage structure not only the tensile and shear failure of the plate,but also the bending,torsion and shear failure of the stiffeners,making the damage mode of the grillage structures more complex.The penetration of ships is the penetration of multilayer grillage structures.The thickness of each board is small,but the space span of multilayer grillage structure is large,so the attitude angle of missile body changes greatly.The change of attitude angle is the key to the penetration ability of projectile.The complexity of the damage modes and the unevenness of distribution of the grillage structure lead to the complex change of the attitude angle of the projectile.Coupled with the dispersion of the impact point,the change of attitude angle presents uncertainty.How to establish the method of describing the uncertainty of the attitude angle of the projectile is the technical bottleneck problem at present.In this paper,the statistical description method of the change of attitude angle of high-speed penetration of grillage structure was studied,the complex damage modes and mechanical characteristics of tensile,bending,shearing and torsional damage of grillage structure were analyzed,the high-speed penetration damage regionalization method of grillage structure was proposed,and the change of attitude angle’s rules of projectile penetrating flat plate and grillage structure was analyzed.Finally,a method to describe the change of attitude angle of grillage structure of ship is established based on statistical method.The main research contents of this paper are as follows:Firstly,the numerical method of projectile penetration is introduced to verify the mesh convergence of the numerical model.The grillage structure was divided into three local structural units,and their motion and stress characteristics were analyzed.The basic units were divided into different damage areas by damage mode,and the highspeed penetration damage regionalization method was formed,which provided the foundation for the subsequent penetration mechanical model and dynamic analysis of the grillage structure.Then,the basic hypothesis that the initial velocity and angle of impact factors were in line with normal distribution was put forward,and the probability density theory formula of the change of attitude angle of the projectile when it penetrated the slab was derived,and the statistical rule of the change of attitude angle of the projectile when it penetrated the flat plate was established.Then,the damage mode of the projectile penetrating the grillage structure was further analyzed.The statistical rule of the change of the attitude angle of the projectile was analyzed by numerical method,and the relationship between the change of attitude angle of the projectile and the position of the impact point of the stiffener was explored.The damage mode of the T-section stiffener wing plates and web plates were analyzed,and different damage modes were found and the statistical rule of the damage mode was divided.Finally,the structural division of the grillage structure was drawn,and the coordinate mathematical model of impact points in line with normal distribution was proposed.The probability of the projectile penetrating the grillage structure at different impact points was calculated by Monte Carlo method,and the probability of the projectile falling into different damage areas was analyzed.The change characteristics of the attitude angle of the projectile penetrating the grillage structure were calculated by numerical simulation,and the statistical characteristics of the change of attitude angle were obtained by extension.Finally,a statistical method to describe the change of attitude angle of projectile penetrating the grillage structure was established. |
