Mechanical Analysis Of Electromagnetic Railgun Barrel Under Non-axisymmetric Loads

Railgun is an entirely new concept of weapons, which has an immeasurableapplication prospects in the defense and military, aerospace, transportation, industrialproduction and scientific research field. Worldwide military technological powerscontinue to strengthen their efforts to carry out the research from a strategic perspective.The current composition of the electromagnetic railgun is too heavy and bulky. One of thereasons is the components’ strength and stiffness calculations are relatively plain and veryfar away from the actual application requirements. Although many railguns constructedduring the past20years have their structural design and consideration of mechanicalenvironment, they have no enough study of mechanical behavior of materials. Currently,railgun’s mechanical research is focused on armature’s machanical characteristics andtrack’s interaction, and barrel’s mechanical research is rarely conducted.Railgun’s cylindrical barrel is actually a length-limited cylindrical shell loaded bynon-axisymmetric loads, which consist of a moving concentrated load and a uniformlydistributed load with synchronously increasing its range of action. The barrel can be alength-limited cylindrical thin shell or thick shell, according to its actual structure. Basedon mechanical state of the cylindrical barrel of railguns, the static characteristcs anddynamic response of a length-limited cylindrical shell under non-axisymmetric loads areresearched through mechanical and mathematical tools in this paper.Railgun’s cylindrical barrel is simplified as a length-limited thin cylindrical shellunder non-axisymmetric line load and concentrated loads. Based on fundamentalequations of the above problem, load function and displacement function are presented,and displacement and stress analytic solutions are obtained by Galerkin Method in thispaper. The analytical solutions are verified by comparing them with ANSYS numericalsolutions of an example problem.Dynamic response of a length-limited cylindrical thin shell under non-axisymmetricloads is researched. Dynamic differential equations with symmetrical forms are derived,and the two moving loads are expressed by the Dirac function and the Heaviside function. Based on the assumed displacement functions, the analytical dynamic solutions to thedisplacement and stress of the cylindrical shell are obtained by means of the Galerkinmethod and Laplace transformation. The algorithm is verified through the comparativeanalysis of the analytical solutions and the ANSYS numerical solutions for a specificexample.Railgun’s cylindrical barrel is simplified as a length-limited thick cylindrical shellunder non-axisymmetric line load and concentrated loads. Based on the assumption ofradial shear strains with quadratic distribution and radial normal strains with lineardistribution through the radial coordinate, displacement expressions containing theunknowns are established. The equilibrium differential equations containing7unkownsare derived according to the minimum potential energy principle. After the selection ofdouble triangle functions and application of the Galerkin Method, analytical solutions ofstress and displacement of thick shells are obtained. This method is verified by acomparative analysis of the analytical solutions with ANSYS numerical results.Dynamic response of a length-limited cylindrical thick shell under non-axisymmetricloads is researched. Based on the assumption of radial shear strains with quadraticdistribution and radial normal strains with linear distribution through the radial coordinate,displacement expressions satisfying boundary conditions are established. After applicationof the Galerkin Method and the Modified Runge–Kutta–Fehlberg Mehtod, dynamicresponse of thick shells is obtained. This method is verified by a comparative analysis ofthe theoretical solutions with ANSYS numerical results from an example.The static characteristics and dynamic responses of the length-limited thin shell andthe thick shell under non-axisymmetric uniform load and concentrated loads are derived inthis paper. They can serve as the foundation of railgun barrel’s structural design, and as areference for static and dynamic analysis of cylindrical shells under non-axisymmetricloads.