Investigating the Effect of Abrupt Change in Geometry on Structural Failure of Artillery Projectile 155 mm

The survivability of artillery projectile 155-mm Extended Range Full Bore Boat Tail (ERFB BT) inside gun barrel during gun launch mainly depends upon the mechanical properties of the shell body, boat tail and driving band materials. Any abrupt change in geometry of any one of these components can impair the structural integrity of the projectile, thereby resulting in malfunctioning of the projectile. Investigating the effect of abrupt change in geometry of the components is of much significance for assessing structural integrity. To investigate the effect of abrupt change in geometry of the components on structural failure, the notch tensile tests are performed to quantify the data on notch strength ratio (NSR), stress triaxiality and true fracture strain of the materials. To identify the mode of failure, the fractographic examination of the fracture surfaces is made. NSR is found more than unity; stress triaxiality determined by applying Bridgman’s analysis reveals notch strengthening behavior of the materials. The fractographic examination shows that the shell body and boat tail materials fail in the combined ductile and brittle mode, whereas the driving band material fails by ductile mode. The outcome of the investigation confirms the load-carrying capacity and structural integrity of the projectile.