Experimental investigation of a cook-off temperature in a hot barrel

AbstractThe experimental investigations of the effect of contact time/temperature on initiating the cook-off using 7.62 mm calibre cartridge cases (CC) were conducted previously. These cartridges were filled with commercial off-the-shelf (COTS) double based (DB) propellant (Bulls Eye) and were loaded in a hot chamber. The thermal explosion temperature is of great significance to both weapon designers and safety inspectors as it provides the operational limit and safe operating temperature. For CC under test, it was found that the cook-off temperatures of this propellant were encountered with the heat transfer profile of the simulated gun barrel between 151.4 °C and 153.4 °C, with a reaction occurring in less than 300 s after the round was chambered. Usefully, each experiment was found to be consistent and repeatable

Ricochet quantification using a multiple sensor approach

This study investigates the ricochet behaviour of three different small-arms projectile types using a novel ricochet measuring device. The results can be used to estimate the danger potential of ricochets on shooting ranges.A ricochet is the change of direction and velocity of a projectile after impacting an oblique surface. This impact produces strong vibrations on a rigid plate. During this impact, flexural waves travel radially outwards from the point of impact. These waves are used to determine the properties of the impactor with accelerometers situated on the target surface. With the use of two measurement plates, one can produce a ricochet and detect the velocity at the same time. Accelerometers are suitable for accurate momentum measurements of single impacts. However, depending upon strike velocity and the impact angle, a ricochet can separate in multiple fragments after being deflected. From the operational safety perspective, these fragments need to be detected, as well. The approach of a coupled sensor concept was chosen to solve this problem. Thermographic sensors were additionally used to visualise the heat which is produced after penetrating a rubber layer pasted in front of the steel target plate. With this approach one was able to detect the position of impact. The investigations showed that the measurement system performance is better with a multiple sensor design, which includes accelerometers for the velocity, impact strength and partly the position measurement, while the thermographic sensor was used for the position measurement and partly the momentum measurement. The investigated ammunition showed plausible fragmentation behaviour, and the results can already be used to estimate the danger potential of different ammunition types. Frangible projectiles fragment to small particles already after being deflected under a small angle. However, Full Metal Jacket projectiles with or without a steel core do not fragment under angles which are less than 5°. The objective of the paper is to demonstrate the possibility of measuring the complex ricochet mechanics of small projectiles using standard accelerometers with the adequate signal processing approach. This measuring system is supported by an off the shelf thermographic camera

Multibody approach for railway dynamic analysis

In the work presented, a computational tool used for the dynamic simulation of railway vehicle systems was developed using multibody systems formulations. The model based on the multibody techniques developed by Shabana. With respect to other exciting methodologies the proposed one make use of a combined frame of references that permit the use of independent coordinates, with out the possibility to have singularity configurations depending on the rotation sequence. The combined frame of references used as a base for the formulation and modeling of wheel-rail contact problem with high precision. The program was designed for considering with a flexible form the different configuration of railway vehicles. The main structure of the program has the ability of making changes for enhancement of the wheel-rail contact model or the implementation of dynamic structure of the track, which considered to be future aspects for a PHD dissertation. The model used was applied to make a simulation for single bogie , also for a complete vehicle with two bogies. The obtained results of the dynamic response for a defined track composed of, tangent segment, transition curve which take the form of a clothoid curve, and finally circular curve with constant radius. The calculations were made for different velocities, lower than the critical in which the vehicle responded in stable form, and higher than the critical at which the instability of the vehicle was studied.Elsayed Abdel Hameed Amer Shaltout, R. (2010). Multibody approach for railway dynamic analysis. http://hdl.handle.net/10251/13763Archivo delegad

Design and implementation of an oil leakage monitoring system based on wireless network

Monitoring pipeline leaks is one of the recent hot studies. Leakage may occur because of time corrosion in the tube raw materials. To reduce the negative consequences of this leak, an effective leak detection system is used to prevent serious leakage accidents and damage in oil pipelines. Buildings, ecosystems, air pollution, and human life are all at risk in case of leakage occurs which could lead to fires. This paper introduces one of the research methods for the detection of pipeline leaks with a particular focus on software-based methods. The computer board interface (CBI) and wireless sensor networks have been used beside Arduino as a micro-monitor for the entire system. ZigBee is also utilized to send read data from sensors to the monitoring system displayed on the LabVIEW graphical user interface (GUI). The operator can take direct action when a leak occurs. The effectiveness of the leakage monitoring process and its practical use are demonstrated by the introduction of computerized techniques based on pressure gauge analysis on a specific pipeline in the laboratory. The result showed that the system is widely covered, accurate data transmission and robust real-time performance which reduces economic losses and environmental pollution

Push-out force and impulse measurement of seven types of small arms ammunition with three different surface states

This study analyzes the influence of lubrication treatments on the force absorbed by the breech bolt called push-out force. The results are of high interest for weapon-safety and durability studies, especially when it comes to weapon maintenance. A barrel-ammunition combination represents an expanding vessel under high pressure. The pressure rises from ambient up to 420 MPa in less than a millisecond. During such a highly dynamic process, purely static equations, describing the problem of the casing push-out force, may not be applied. Besides the dynamic behavior, the surface properties and geometry also play an important role. To investigate the push-out force, a measurement system based on a force washer was built. This system was validated using a crusher method and finite element analysis. The impulse was calculated using the data of the measured force to obtain additional information about the force-time properties of the push-out behavior. Untreated ammunition and two lubrication systems: “ice layer” and “oil lubricated,” as well as seven different ammunition sizes ranging from 5.56 to 12.7 mm were considered. The response was the force absorbed by the bolt while the cartridge provides rear obturation to the combustion gases. It was found that both the casing geometry and its treatments have a significant influence on the push-out force

Comparison of the microstructure of machined and laser sintered shaped charge liner in the hydrodynamic regime

To gain further insight into the mechanisms underlying jet formation and elongation of laser sintered shaped charge liners under high strain rate deformation, Cu–Cr–Zr alloy liners fabricated by selective laser sintering process were deformed by explosive detonation. Their as-manufactured (liner) and resultant (slug) microstructure have been investigated in comparison with those of traditional machined liners employing both optical and scanning electron microscopy. The resultant slug microstructure of both machined and laser sintered liners revealed a smaller refined equiaxed grain size consistent with traditionally fabricated liners, characteristic of dynamic recrystallization. The disappearance of the (originally present) pores in the post-shot/recovered material microstructure was observed for laser-sintered liners. Comparison of the forward and rear region of the slug revealed variations in liner deformation, a result attributed to temperature variation across the slug. In contrast with the machined liner, a unique feature of precipitation, observed in the ending (slug) microstructure of the laser sintered liner is indicative of the associated extreme high strain and strain rate liner deformation which occurred during slug formation. The precipitates are likely compounds of Chromium and Zirconium which are constituents of the laser sintered copper alloy—the first time this observation is reported. This study provides a link between post charge evolution microstructure and liner manufacturing processes, potentially providing a new route to help optimise jet formation and effectiveness

A review of dual-spin projectile stability

This paper gives a succinct review of dual-spinprojectile stability and some technologies relating to them. It describes how the traditional stability factors from linear projectile theory are modified to better describe a controlled dual-spin projectile. Finally, it reviews works which have investigated how different aspects of a controlled dual-spin design can affect flight stability, primarily airframe structure and canard properties. A conclusion is given, highlighting important guidelines from the enclosed discussion

NGL and N / L in the diagnosis of PE

Many hypotheses underlie the pathogenesis of preeclampsia. This study aims to evaluate Neutrophil gelatinase-associated lipocalin (a marker of immune hypothesis) and Neutrophil / Lymphocyte ratio (a marker of inflammation) in the diagnosis of preeclampsia and its severity and to determine the correlation between them. Study design : This randomized case-control study involved 132 pregnant women ; 88 were diagnosed with PE (divided into non-severe and severe groups), and 44 healthy pregnant women as a control group. Results : The mean serum level of NGL was significantly higher in PE (535.37 ± 158.61 ng / ml for severe PE, 522.5 ± 106.3 ng / ml for non-severe PE, and 161.96 ± 17.48 ng / ml for the control group). The ROC Curve NGL criteria of more than 204.4 ng / ml showed 100% sensitivity and specificity in both severe and non-severe cases versus control. The N / L ratio showed a significant difference (5.81 ± 5.24 for severe PE, 4.1 ± 3.41 for non-severe PE, and 3.89 ± 1.79 for the control group), but the ROC curve criterion was not significant. Both showed a non-significant positive correlation. Conclusion : NGL is an excellent diagnostic factor, whereas N / L might have lower diagnostic performance compared with NGL. Both are related independently to the pathophysiology of PE

The dynamic response of dense 3 dimensionally printed polylactic acid

Polylactic acid (PLA) is commonly used as a feedstock material for commercial 3D printing. As components manufactured from such material become more commonplace, it is inevitable that some of the resultant systems will be exposed to high strain-rate/impact events during their design-life (for example, components being dropped or even involved in a high-speed crash). To this end, understanding the shock properties of polylactic acid, in its role as a major raw material for 3D printed components, is of particular importance. In this work, printed samples of PLA were deformed by one-dimensional shock waves generated via the plate impact technique, allowing determination of both the Hugoniot Equation of State (EOS) and shear strength of the material. Both linear and non-linear EOS forms were considered in the US-Up plane, with the best-fit found to take the general form US=1.28+3.06−1.09Up2" role="presentation" style="display: inline-table; line-height: normal; letter-spacing: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border-width: 0px; border-style: initial; position: relative;">US=1.28+3.06−1.09U2pUS=1.28+3.06−1.09Up2 in the Us−Up" role="presentation" style="display: inline-table; line-height: normal; letter-spacing: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border-width: 0px; border-style: initial; position: relative;">Us−UpUs−Up plane, consistent with other polymers. Use of lateral Manganin gauges embedded in the material flow allowed consideration of lateral stress evolution at impact pressures ranging from 0.3 to 4.0 GPa. Shear strength was observed to increase with impact stress, however, with minimal strengthening behind the shock front. Deviation of the measured stress from the predicted elastic measurement (corresponding to the PLA’s Hugoniot Elastic Limit) was observed at longitudinal stress of 0.90 ± 0.05 GPa, within range of polymeric materials of similar characteristics—the first time this important parameter has been measured for PLA. As a result, this material characterisation will allow numerical modellers to accurately predict the structural response of PLA-based components/structures against high strain rates such as impacts or drops

The variance on the shock response of a carbon fibre composite due to the orientation of the weave

Three different orientations of a tape-wrapped carbon fibre composite with phenolic resin matrix (abbreviated to TWCP) have been investigated under one-dimensional shock loading. This has been achieved via a single-stage gas gun, with manganin gauges as the diagnostic tool. The orientations of TWCP studied in this paper were 25°, 45° and 90°, with respect to the impact face. The shock response of these orientations, for this material, has been obtained (the Hugoniot equation of state). These results have been contrasted with previously reported literature data for the same material at different orientations (0° and 20°). It was found that orientation had minimal effect on the behaviour of this composite under shock. The exception to this was the 90° orientation which exhibited an elastic precursor at particle velocities of less than 0.65 mm µs−1; where the shock velocity was equivalent to the elastic sound speed of the material