Probabilistic Modeling for Ceramic Lined Gun Barrels

Designers of advanced gun systems have been tasked with increasing barrel life in the face of the extreme erosion and wear of the interior ballistics environment. The addition of refractory metal coatings, such as chromium or tantalum, have greatly boosted service life, but even with these applications the erosion resistance of the underlying gun steel is the service-life limiting factor. The U.S. Army Research Laboratory (ARL) is currently undertaking an effort to determine the feasibility of ceramic gun barrels. Ceramics are attractive for liner materials because of their high-temperature performance and erosion-resistance characteristics. Unfortunately, their drawbacks are low tensile strength, low fracture toughness, and brittle fracture. Previous research into the replacement of metals with a ceramic liner has met with limited success, at best, but advances in ceramic manufacturing technology, probabilistic design, and sheathing technology have led to renewed interest in this area. The work at ARL has focused on developing a material property database of commercially available ceramics, extensive finite element and analytic modeling, experimental verification, and, ultimately, demonstration of the ceramic gun barrel technology. This body of work will focus on the derivation of analytic models for an N-layered tube to calculate the Weibull failure probabilities for a ceramic liner. Model results are verified through high-pressure burst testing of blank and sheathed ceramic tubes. The application of the models as a design tool is explored by generating failure surface plots to investigate optimal geometries and prestress levels for a variety of different liner and sheath materials across various caliber systems.