DYNAMIC STRESS ANALYSIS FOR PROJECTILES

PROJECTILES LAUNCHED AT HYPERVELOCITIES AT THE BALLISTIC RANGES OF ARNOLD ENGINEERING DEVELOPMENT CENTER ARE SUBJECT TO EXTREME LOADS OF OVER 100,000 G'S AND OCCASIONALLY FAIL. THE ULTIMATE MATERIAL STRENGTH, IN PRACTICE, LIMITS THE MAXIMUM SPEED TO WHICH THE PROJECTILE CAN BE LAUNCHED AND STILL REMAIN INTACT. THE PROJECTILES ARE CONSTRUCTED FROM A VARIETY OF MATERIALS INCLUDING METALS, PLASTICS, AND COMPOSITES AND MAY UNDERGO LARGE PLASTIC DEFORMATIONS. AN UNDERSTANDING OF THE DYNAMICS OF A PROJECTILE AND ITS INTERACTION WITH THE LIGHT GAS AND BARREL WALL COULD LEAD TO IMPROVED PROJECTILE DESIGNS AND OPERATIONAL PROCEDURES TO REDUCE THE POSSIBILITY OF MODEL FAILURE WITHOUT DEGRADING THE OVERALL PERFORMANCE OF THE GAS GUN. THIS PROPOSAL ADDRESSES THE NEED FOR AN ANALYTICAL TOOL TO ACCURATELY SIMULATE THE PROJECTILE DYNAMIC STRESSES. UNDER PHASE I, A PROTOTYPE FINITE ELEMENT CODE WILL BE DEVELOPED AND TESTED FOR SIMPLE AXISYMMETRIC PROJECTILES TO ASSESS THE FEASIBILITY OFCONDUCTING REALISTIC SIMULATIONS. THE EFFECTS OF SIDE PRESSURE BLOW-BY, MATERIAL NONLINEARITIES, AND FRICTION WILL BE STUDIED.