A concise review on degradation of gun barrels and its health monitoring techniques

Unpredicted failure of barrels is a common problem for cannons, artilleries, and other ballistic missiles. The major cause of the barrels' failure is high pressure, which generates large residual stresses in the inner layers of the barrel. To reduce the stresses, autofrettage of the barrels is carried out in which the core material is allowed to deform plastically and the upper layers produce a continuous elastic force over the inner layers. Autofrettage is a common engineering practice which is carried out while manufacturing of barrels to increase the operational life significantly. The other reason for barrel failure is material degradation which occurs due to thermal fluctuations, fatigue, wear, erosion, corrosion, etc. In order to correlate them with the life of the gun barrels, various tools such as borescope, variety of gauges, optical bore-mapping, ultrasonic sensors, and diamond indenter-based instruments are used. The measured data is then used to formulate the empirical mathematical relation which is further used to calculate the remaining useful life of the barrels. The other mathematical models are the prognostics models which are generally Probabilistic models or Data-driven models (such as machine learning) or Hybrid models. By using these models, we estimate the remaining life of barrels by using any of the techniques such as heat emission method, dimension increment method, muzzle velocity method, and strain-based methods. The paper concisely summarize various techniques used for diagnostic and prognostic of barrels to estimate the degradation profile and to calculate the remaining useful life (RUL).