The emphasis on lightweight large-caliber weapons systems has placed the focus on the use of advanced composite materials. Using composite materials not only directly removes weight from the gun tube but, by better balancing the tube, allows the use of smaller gun stabilization drive systems, thus further enhancing system weight loss. Additionally, the use of high stiffness composites helps with pointing accuracy and alleviating the dynamic strain phenomenon encountered with high-velocity projectiles. Traditionally though, using composites has been difficult because of the coefficient of thermal expansion mismatch between the steel substrate and the composite jacket, which causes a gap after manufacturing. Dealing with this mismatch has greatly complicated the manufacturing process in the past to the point where mass-producing the barrels would be problematic at best. By using a thermoplastic resin and a cure on the fly process, the manufacturability of the barrels has been greatly improved and the gap has been eliminated. This is the first time that this approach has been applied to a large-caliber gun tube. A 120 mm barrel has been manufactured using this process with IM7 fibers in a polyetheretherketone matrix and successfully test fired. This paper will present the design, manufacturing, and test firing of this barrel.

This paper describes a range of hydraulic fatigue and pressure tests carried out on gun barrels and ordnance components in support of weapons research and development programs. Cyclic testing of representative sections of large caliber guns has been routinely carried out to determine safe fatigue life for operational use. Ultrasonic techniques have been developed for mapping multiple cracks within the gun barrels by which periodic examinations of barrels during testing have been used to build up histories of crack initiation and growth. In relatively unworn barrels multiple cracks, initiated along each rifling groove, are shown to form in an extremely stable array that can grow to several millimeters depth, in agreement with calculated stress intensity factors, before one crack accelerates to dominate final failure. The development of localized erosion from extensive firing is shown to significantly affect the subsequent hydraulic fatigue cycling by generation of only one or two cracks as well as the prior removal of heavily prestressed bore material. Tests on fume extractor sections of barrels show that cracking initiates in the jet holes and only grows to the bore at late stages. Introduction of different levels of autofrettage acts to bias the radial location of the cracks. An extensive experimental program of work has been carried out in support of design studies on mid-wall cooled gun barrels exploring a number of different configurations for construction of compound tubes and the results of numerical simulations of the assembly process have been compared with strain gauge measurements during the experimental procedure on scale tubes. Subsequent hydraulic cycling was used to determine the fatigue implications of the processing route.

The uniaxial Bauschinger effect has been evaluated in several high strength steels being considered for armament application. The steels investigated include ASTM A723 (1130 and 1330 MPa), PH 13-8 Mo stainless steel (1380 MPa), PH 13-8 Mo super tough stainless steel (1355 MPa), and HY 180 (1180MPa). Tests were conducted at plastic strains up to 3.5%. Results of testing show a progressive decrease in Bauschinger effect up to plastic strains of approximately 1% (for all materials investigated), after which there is little further decrease in the Bauschinger effect. Several key features were discovered during testing. First, all of the materials tested exhibited a changing modulus, where the elastic modulus on unloading after tensile plastic straining is consistently lower than that observed in the original loading of the specimens. The amount of modulus reduction is dependent upon the material tested, and larger reductions are observed with increasing amounts of tensile plastic strain. Prior work by Milligan reported Bauschinger effect factor β for a modified 4340 steel (old vintage A723 steel), which compares well with the present work. However, his results failed to mention any observations about a modulus reduction. The second observation was the expected strength reduction where a reduced compressive strength is observed as a result of prior tensile plastic straining. Numerical curve fits used to calculate residual stresses, which take into account both the modulus reduction and strength reduction are presented for all materials. Fatigue life calculations, utilizing the numerical curve fits, show good agreement with full size A723 laboratory fatigue test results.

This paper presents a study on using high-pressure ammonia and abrasive ammonia jets for cutting and washout of chemical weapons. The work focused on chemical rocket M55 simulants. A test chamber was built to cut M60 training and M61 practice rockets at Redstone Arsenal by Teledyne-Commodore who developed a complete destruction process using alkali metals dissolved in anhydrous ammonia to form the aggressive solvated electron technology (SET™) solution. The rocket is loaded in a rotary chuck and stationary cutting/piercing nozzles were used to cut and drill through the rocket. This approach was found to be effective due to minimizing the number of moving parts. High-pressure direct drive and intensifier pumps were developed for this application. It was found that intensifier-based pumps are more suitable for robust field use. The abrasive ammonia jets performed well for cutting the rocket metal shell (aluminum and steel) casing as well as the outside fiberglass case. A wash-out-ammonia jet lance has also been found to completely wash out the simulant materials. Over 20 rockets were successfully cut by Teledyne personnel without any incidents. It was concluded that the use of anhydrous ammonia has numerous advantages over conventional water for chemical weapon demilitarization applications.

It is estimated that more than 500,000 tons of obsolete and unwanted conventional weapons exist in the United States. The disposal of these unexploded ordnances, in an environmentally sound and cost-effective way, is of paramount importance. Open-air burning and open-air detonation (OB/OD) are two of the most widely used methods to dispose of these unwanted energetic materials. This paper describes our efforts to improve OB/OD operations through the design and testing of a new, large-scale, partially confined facility that minimizes the adverse affects of far-field noise and maximizes the afterburn of explosive by-products. Several designs were evaluated by a series of axisymmetric, time-dependent numerical simulations using FAST3D, a flux-corrected transport-based code optimized for parallel processing. The simulations are used to test various facility geometries and placements and sizes of charges to determine combinations that result in acceptable environmental impact. Comparisons of the pressure and structural analyses for 50 and 100 lb of spherically shaped RDX charges show that the 50-lb spherically shaped charge placed at a height of approximately 2.0 m resulted in an efficient detonation and maintained the structural integrity of the detonation facility.

More than 500,000 tons of obsolete and unwanted conventional weapons exist in the United States. The disposal of these unexploded ordnances, in an environmentally sound and cost-effective way, is of paramount importance. Different types of incinerators and detonation chambers have been proposed to eliminate these unwanted energetic materials. However, questions about the design of such facilities and the environmental consequences of their use must be answered. This paper describes numerical simulations of a large-scale, partially confined detonation facility. Detonation facility designs were evaluated by a series of axisymmetric, time-dependent simulations using FAST3D, a numerical model based on flux-corrected transport coupled to the virtual cell embedding algorithm for simulating complex geometries. The simulations assisted in determining the shape and size of the detonation charge mass that maintained the structural integrity of the facility. Comparisons of the pressure and structural analyses for spherically and cylindrically shaped RDX charges in a fixed volume show that the 50-lb spherically shaped charge resulted in an efficient detonation and maintained the structural integrity of the detonation facility.