120 mm Prestressed Carbon Fiber/Thermoplastic Overwrapped Gun Tubes

Abstract

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 also, by better balancing the tube, allows the use of smaller drive systems, thus further enhancing the system weight loss. Additionally, the use of high stiffness composites helps with pointing accuracy and to alleviate the dynamic strain phenomenon encountered with high velocity projectiles. Traditionally, there were two issues with composite jackets: the coefficient of thermal expansion mismatch between the steel substrate and the composite jacket causing a gap and the lack of favorable prestress in the jacket. Dealing with these issues greatly complicated the manufacturing process to the point where mass-producing the barrels would have been problematic at best. By using a thermoplastic resin, a cure on the fly process, and winding under tension, the manufacturability of the barrels has been greatly improved, the gap has been eliminated, and a favorable prestress has been achieved. Four 120 mm barrels have been manufactured using this process with IM7 fibers in a PEEK matrix and successfully test fired. The first barrel was not prestressed and was reported on previously. This paper will focus on the other three barrels. The design, manufacturing, and test firing of these barrels will be covered.

Critical velocities and displacements of anisotropic tubes under a moving pressure

“…For orthotropic tubes under a moving pressure, a critical velocity formula has also been reported (without derivations) by Tzeng and Hopkins [11] based on Love’s thin cylindrical shell theory, which does not consider the effects of shear deformations and rotary inertia [12]. As a result, more accurate formulas that account for these effects are still in need for orthotropic and other anisotropic tubes, which can represent lightweight composite tubes [13–15].…”

Critical velocities of a two-layer composite tube under a moving internal pressure

“…Efforts have been made to determine critical velocities of single-layer, homogeneous tubes of materials with various types of symmetry, including isotropic, cubic, transversely isotropic and orthotropic (e.g., [10,11,15,27,30,35,36]). However, for composite tubes containing two or more cylindrical layers of dissimilar materials (e.g., [20,21,29]), very few studies have been conducted to find their critical velocities. Jones and Whittier [16] investigated the harmonic wave propagation in an infinitely long two-layered axisymmetric cylindrical shell using a Timoshenko-type shell theory similar to those of Lin and Morgan [19] and Herrmann and Mirsky [14], but they did not include any discussion on critical velocities of the composite cylinder.…”

Improved the surface properties of carbon fiber through hyperbranched polyaryletherketone sizing

“…[1] As the resin matrix of advanced composite materials, poly(ether ether ketone) (PEEK) plays an important role in the field of high temperature resistance. At the same time, carbon fiber reinforced PEEK (CF/PEEK) composite materials have also been widely used in aerospace, [2][3][4] ships, submersible, vehicles, [5] military industry, [6,7] energy and electricity. [8][9][10][11] However, the molecular chain of PEEK is rigid and non-polar, and its molten state viscosity is high, when it is used as a composite matrix, it has poor wettability to CFs and weak bonding force with CFs, so PEEK needs to be modified.…”