96 research outputs found
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Penetration into limestone targets with ogive-nose steel projectiles
We conducted depth of penetration experiments into limestone targets with 3.0 caliber-radius-head, 4340 Rc 45 steel projectiles. Powder guns launched two projectiles with length-to-diameter ratios of ten to striking velocities between 0.4 and 1.5 km/s. Projectiles had diameters and masses of 12.7 mm, 0. 117 kg and 25.4 mm, 0.610 kg. Based on data sets with these two projectile scales, we proposed an empirical penetration equation that described the target by its density and an empirical strength constant determined from penetration depth versus striking velocity data
One dimensional model of thermo-capillary driven liquid jet break-up with drop merging [electronic resource]
A numerical model is presented for predicting the instability and breakup of liquid jets of Newtonian fluid driven by thermo-capillary perturbations. The model uses a one-dimensional slender-jet approximation to obtain the equations of motion in the form of a set of coupled nonlinear partial differential equations (PDEs). These equations are solved using the method-of-lines (MOL), wherein the PDEs are transformed to a system of ordinary differential equations (ODEs) for the nodal values of the jet variables on a uniform staggered grid. The model predicts instability and satellite formation in infinite threads of fluid and continuous jets that emanate from an orifice. The model is validated using established computational data, as well as axisymmetric, volume of fluid (VOF) computational fluid dynamic (CFD) simulations. The key advantages of the model are its ease of implementation and speed of computation that is several orders of magnitude faster than the VOF CFD simulations. The model enables rapid parametric analysis of jet breakup and satellite formation as a function of jet dimensions, modulation parameters, and fluid rheology. The model also incorporates post break-up behavior by providing methods for the fission of the jet into discrete ligaments and drop. Each separate ligament is assigned its own computational domain that is passed to the ODE solver in lockstep. Furthermore, some drops merge downstream as a results of their velocity differentials at the point of break-up; the model implements drop merging by blending discrete computational domains into one, using cubic interpolation and third-order polynomials to create a liquid bridge between the two. The study of merging behavior has application in the field of inkjet printing, wherein the thermal pulse to the surface of a jet is modulated to create different drop volumes. The model reveals that larger than usual drops do not spontaneously form at the end of the filament; they first break into smaller pieces which coalesce downstream
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Perforation of HY-100 steel plates with 4340 R{sub c} 38 and T-250 maraging steel rod projectiles
The authors conducted perforation experiments with 4340 Rc 38 and T-250 maraging steel, long rod projectiles and HY-100 steel target plates at striking velocities between 80 and 370 m/s. Flat-end rod projectiles with lengths of 89 and 282 mm were machined to nominally 30-mm-diameter so they could be launched from a 30-mm-powder gun without sabots. The target plates were rigidly clamped at a 305-mm-diameter and had nominal thicknesses of 5.3 and 10.5 mm. Four sets of experiments were conducted to show the effects of rod length and plate thickness on the measured ballistic limit and residual velocities. In addition to measuring striking and residual projectile velocities, they obtained framing camera data on the back surfaces of several plates that showed clearly the plate deformation and plug ejection process. They also present a beam model that exhibits qualitatively the experimentally observed mechanisms
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