Simplified Interior Ballistics Analysis of a Tube Launched UAV Prototype

Structural analysis is a critical aspect in the successful design of tube launched projectiles, such as mortar rounds. Ongoing research conducted at West Virginia University has focused on a tube-launched, folding-wing UAV design inspired by mortars. This has driven the necessity of a structural analysis of the prototype design to provide vital feedback to designers to ensure that the UAV is likely to survive the act of launching. Due to the extreme accelerations during the launching phase, a typical mortar round experiences dramatic impulse loads for an extremely brief duration of time. Such loads are the result of the propellant combustion process. Thermodynamic-based interior ballistic computations have been formulated and were used to solve the dynamic equations of motion that govern the system. Modern ballistic programs solve these equations by modeling the combustion of the propellant. However, mathematical procedures for such analyses require complex models to attain accurate results. Consequently, the objective of this research is to create a ballistics program that can evaluate interior ballistics by using archived pressure-time data without having to simulate the propellant combustion in order to minimize the computational effort required. A program routine created for this purpose reduces the complexity of calculations to be performed, while maintaining a reasonable degree of accuracy for the motion dynamics results (temporal displacement, velocity, acceleration of the projectile) and thermodynamic results (combustion gas pressure and volume). Additionally, the program routine was used to produce a mathematical model describing the pressure as a function of time. Advanced simulations could then be conducted via explicit-dynamic finite element solvers such as ANSYS LS-DYNA using the ballistics code outputs as loading conditions to simulate the transient response and stress wave propagation of the prototype and individual payload components. Such simulations remove uncertainties related to the transient loads needed to assess the structural integrity of the projectile and its components. Results obtained from the simulations were compared for verification purposes to review the accuracy of the solutions. The program provided researchers with an effective design tool that may be used in the optimization of a successful structural design. The results obtained from the simulations will be examined in the context of this thesis