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Creep Testing Plastic-Bonded Explosives in Uni-axial Compression

Description: High fidelity measurements of time-dependent strain in the plastic-bonded explosives LX-17-1 and PBX 9502 have been performed under constant, uni-axial, compressive load using a custom designed apparatus. The apparatus uses a combination of extensometers and linear variable differential transformers coupled with a data acquisition system, thermal controls, and gravitational loading. The materials being tested consist of a crystalline explosive material mixed with a polymeric binder. The behavior of each material is related to the type of explosive and to the percentage and type of binder. For any given plastic-bonded explosive, the creep behavior is also dependent on the stress level and test temperature. Experiments were conducted using a 3 x 3 stress-temperature matrix with a temperature range of 24 C to 70 C and with stresses ranging from 250-psi to 780-psi. Analysis of the data has shown that logarithmic curve fits provide an accurate means of quantification and facilitate a long-term predictive capability. This paper will discuss the design of the apparatus, experimental results, and analyses.
Date: March 13, 2008
Creator: Gagliardi, F J & Cunningham, B J
Partner: UNT Libraries Government Documents Department

Terminal ballistic experiments for the development of turbine engine blade containment technology

Description: The ballistic experiments reported herein were conducted in three sets between October 1993 and November 1994. The first set of experiments examined the ballistic failure of annealed titanium plates. These experiments were performed in a manner consistent with earlier experiments conducted at United Technologies` Pratt and Whitney Division. The second set of experiments examined the ballistic performance of select aluminum and titanium alloys in single-plate and laminate form. In both sets of experiments, the failure modes of the targets were observed and catalogued. The third set of experiments evaluated underlying issues associated with geometric scaling. Blunt .30-and .50-caliber hard steel projectiles impacted on geometrically similar annealed titanium plates.
Date: January 25, 1995
Creator: Gogolewski, R.P. & Cunningham, B.J.
Partner: UNT Libraries Government Documents Department

Dynamic Characterization of Mock Explosive Material Using Reverse Taylor Impact Experiments

Description: The motivation for the current study is to evaluate the dynamic loading response of an inert mock explosive material used to replicate the physical and mechanical properties of LX-17-1 and PBX 9502 insensitive high explosives. The evaluation of dynamic material parameters is needed for predicting the deformation behavior including the onset of failure and intensity of fragmentation resulting from high velocity impact events. These parameters are necessary for developing and validating physically based material constitutive models that will characterize the safety and performance of energetic materials. The preliminary study uses a reverse Taylor impact configuration that was designed to measure the dynamic behavior of the explosive mock up to and including associated fragmentation. A stationary rod-shaped specimen was impacted using a compressed-gas gun by accelerating a rigid steel anvil attached to a sabot. The impact test employed high-speed imaging and velocity interferometry diagnostics for capturing the transient deformation of the sample at discrete times. Once established as a viable experimental technique with mock explosives, future studies will examine the dynamic response of insensitive high explosives and propellants.
Date: March 25, 2010
Creator: Ferranti, L; Gagliardi, F J; Cunningham, B J & Vandersall, K S
Partner: UNT Libraries Government Documents Department

On the importance of target materials interfaces during low speed impact

Description: We are conducting a Cooperative Research and Development Project under the sponsorship of the U.S. Department of Energy to determine the applicability of aluminum particulate reinforced alloy laminates to aircraft structures and for containment of aircraft engine turbine blades and debris due to catastrophic engine failure. Within this framework, we are studying the terminal interaction of projectiles impacting targets at speeds of 150- to 500 m/s. Our presentation focuses on a special series of experiments and computational physics analyses of 6061-T6 aluminum alloy targets in single plate and laminate form impacted by steel cylindrical projectiles. Four cases are examined, projectile impact into (1) a single plate, (2) three contiguous plates (frictional interfaces), (3) three contiguous plates separated by Teflon layers (frictionless interfaces), and (4) a spaced array of three plates. We found that the ratio of projectile kinetic energies just at target perforation for the highest to lowest critical projectile speeds over the four targets is 1.75. Considering that target areal density is held constant across the four targets, this is a dramatic result. 2 refs., 7 figs.
Date: July 1996
Creator: Gogolewski, R. P.; Cunningham, B. J.; Riddle, R.; Lesuer, D. & Syn, C.
Partner: UNT Libraries Government Documents Department

A Constitutive Model for Long Time Duration Mechanical Behavior in Insensitive High Explosives

Description: An anisotropic constitutive model for the long term dimensional stability of insensitive high explosives is proposed. Elastic, creep, thermal, and ratchet growth strains are developed. Pressure and temperature effects are considered. The constitutive model is implemented in an implicit finite element code and compared to a variety of experimental data.
Date: March 9, 2010
Creator: Darnell, I M; Oh, S; Hrousis, C A; Cunningham, B J & Gagliardi, F J
Partner: UNT Libraries Government Documents Department

Fracture toughness and impact properties of laminated metal composites

Description: Laminated metal composites consist of alternating metal (or metal matrix composite) layers bonded together. These materials can provide fracture toughness and impact properties superior to those of the component materials. These properties are a function of component material properties, laminate architecture (volume fraction, thickness) and interface properties. Properties are compared for seven lightweight materials.
Date: March 4, 1996
Creator: Lesuer, D.R.; Riddle, R.A.; Gogolewski, R.P.; Syn, C.K. & Cunningham, B.J.
Partner: UNT Libraries Government Documents Department

Impact studies of five ceramic materials and pyrex

Description: We measured the ballistic performance of five ceramic materials (alumina, silicon carbide, boron carbide, aluminum nitride, and titanium diboride) and Pyrex, when they are backed by thick steel plates. The projectile for all tests was a right-circular cylinder of tungsten sinter-alloy W2 with length 25.4 mm and diameter 6.35 mm, fired at velocities from 1.35 to 2.65 km/s. For this threat we determined the minimum areal density of each material that is needed to keep the projectile from penetrating the backup steel. For all of the facing materials studied here, this performance measure increases approximately linearly with projectile velocity. However, the rate of increase is significantly lower for aluminum nitride than for the other materials studied. Indeed, aluminum nitride is a poor performer at the lowest velocity tested, but is clearly the best at the highest velocity. Our computer simulations show the significant influence of the backing material on ceramic performance, manifested by a transition region extending two projectile diameters upstream from the material interface. Experiments with multiple material layers show that this influence also manifests itself through a significant dependence of ballistic performance on the ordering of the material
Date: May 22, 1998
Creator: Cunningham, B. J.; Holt, A. C.; Hord, B. L.; Kusubov, A. S.; Reaugh, J. E. & Wilkins, M. L.
Partner: UNT Libraries Government Documents Department

A modification of 4330 alloy steel

Description: We have developed a modification of 4330 alloy steel which does not have an exact equivalent expressed in any standard specification. When we compare the ballistic performance of our modified cast steel in thicknesses of about 120 mm with that of stacked, 24 mm thick rolled 4340 alloy steel plates of comparable hardness and the same total thickness, we do not find a significant difference in terminal ballistic performance against either heavy metal kinetic energy penetrators or precision shaped charges. This result is surprising in relation to contemporary experience in which cast steel has been found to be ballistically inferior to rolled steel against either kinetic energy projectiles or shaped charge warheads. 1 ref., 9 figs.
Date: August 1, 1990
Creator: Gogolewski, R.; Cunningham, B.J. (Lawrence Livermore National Lab., CA (USA)); Gentile, R. & Fleming, S. (Norton Defense Systems, Mahwah, NJ (USA))
Partner: UNT Libraries Government Documents Department