Modeling of Three-Dimensional Stress-Strain State and Strength Analysis of Metal Composite Cylinders under Impulsive Loading Using the Conwep Method

The application package previously developed at the Pisarenko Institute of Problems of Strength of the National Academy of Sciences of Ukraine for the numerical calculation of the dynamic non-axisymmetric three-dimensional stress-strain state and strength of multilayer helically orthotropic cylinders of finite length under impulsive loading was modified by the CONWEP method for load due to the explosion of a spherical explosive charge arbitrarily located in air inside a cylinder. Its accuracy was investigated by the variation of grid size, the number of the terms of Fourier expansions of unknowns, boundary conditions, charge coordinates and other input parameters. The three-dimensional dynamics and strength of composite and metal-composite cylinders loaded by a non-axisymmetric internal explosion were studied. Strength was determined by the generalized Mises criterion. The influence of displacement of the explosive charge relative to the center of symmetry of the cylinder along the radius and axis on stress-strain state and strength was studied. It is shown that at the constant relative mass of the charge, metal-composite cylinders can be made equally strong by increasing the thickness of the metal layer from zero to a quarter of the shell thickness, while increasing the mass of the charge by a factor of almost two. The inefficiency of the use of reinforced composites with low ultimate tensile strength across fibers in such structural elements has been established. It is shown that in some cases adding an outer composite layer to the inner steel shell leads not to an increase but on the contrary to a decrease in the strength of the object as a whole.