scholarly journals High-Velocity Impacts of Pyrophoric Alloy Fragments on Thin Armour Steel Plates

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4649
Author(s):  
Evaristo Santamaria Ferraro ◽  
Marina Seidl ◽  
Tom De Vuyst ◽  
Norbert Faderl
Keyword(s):  
High Velocity ◽  
High Speed ◽  
Failure Modes ◽  
Threshold Value ◽  
Steel Plates ◽  
Terminal Ballistics ◽  
High Velocity Impacts ◽  
Modern Warfare ◽  
The Impact ◽  
Armour Steel

The terminal ballistics effects of Intermetallic Reactive Materials (IRM) fragments have been the object of intense research in recent years. IRM fragments flying at velocities up to 2000 m/s represent a realistic threat in modern warfare scenarios as these materials are substituting conventional solutions in defense applications. The IRM add Impact Induced Energy Release (IIER) to the mechanical interaction with a target. Therefore, the necessity of investigations on IIER to quantify potential threats to existing protection systems. In this study, Mixed Rare Earths (MRE) fragments were used due to the mechanical and pyrophoric affinity with IRM, the commercial availability and cost-effectiveness. High-Velocity Impacts (HVI) of MRE were performed at velocities ranging from 800 to 1600 m/s and recorded using a high-speed camera. 70 MREs cylindrical fragments and 24 steel fragments were shot on armour steel plates with thicknesses ranging from 2 mm to 3 mm. The influence of the impact pitch angle (α) on HVI outcomes was assessed, defining a threshold value at α of 20°. The influence of the failure modes of MRE and steel fragments on the critical impact velocities (CIV) and critical kinetic energy (Ekin crit) was evaluated. An energy-based model was developed and fitted with sufficient accuracy the Normalised EKin crit (E˜kincrit) determined from the experiments. IIER was observed in all the experiments involving MRE. From the analyses, it was observed that the IIER spreads behind the targets with velocities comparable to the residual velocities of plugs and shattered fragment.

scholarly journals Experimental analysis of high velocity impacts of composite fragments on aluminium plates

2021 ◽  
Vol 250 ◽  
pp. 01011
Author(s):  
Jorge López-Puente ◽  
Jesús Pernas-Sánchez ◽  
José Alfonso Artero-Guerrero ◽  
David Varas ◽  
Joseba Múgica ◽  
...  
Keyword(s):  
High Velocity ◽  
High Speed ◽  
Woven Composites ◽  
Residual Velocity ◽  
Video Cameras ◽  
High Speed Video ◽  
High Velocity Impacts ◽  
Deformable Structure ◽  
The Impact ◽  
Composite Blades

The improvement of engines is one of the ways to diminish the fuel consumption in civil aircrafts, and Open Rotors engines are one of the best promises in order to achieve a sensible efficiency increment. These engines have large composite blades that could, in the event of failure, impact against the fuselage, totally or partially. In this case, composite fragments could behave as impactors. In order to design fuselages for this event and adopt these new engines in the future, it is necessary to understand the impact behaviour of a composite fragment against a deformable structure. To this end, unidirectional and woven composites fragments were impacted at high velocity (up to 150 m/s) against aluminium panels at different impact velocities. The composite fragments were made using AS4/8552 (UD) and AGP-193PW (woven) prepregs manufactured by Hexcel Composites, both using AS4 fibres and 8552 epoxy matrix. High speed video cameras were used to record the impact process and to measure both the impact and the residual velocity and hence the energy absorbed.

scholarly journals Influence of Add-On Perforated Plates on the Protective Performance of Light-Weight Armour Systems

2018 ◽  
Vol 9 (1) ◽  
pp. 31-48
Author(s):  
Teresa FRAS ◽  
Norbert FADERL
Keyword(s):  
Hard Core ◽  
High Hardness ◽  
Steel Plates ◽  
Perforated Plates ◽  
Geometrical Properties ◽  
Impact Position ◽  
Circular Holes ◽  
Protective Performance ◽  
The Impact ◽  
Armour Steel

The presented experimental investigation, aimed at verification of defeat mechanisms against small-calibre projectiles, provided by 4-mm-thick perforated plates with different material- and geometrical properties, was performed. A regular pattern of punched holes in steel plates increases the possibility of asymmetrical contact between the plate and projectiles which may cause threat destabilization, rotation or fragmentation depending on the impact position. Three tested armour configurations comprise the super-bainitic high-hardness Pavise™ SBS 600P armour steel plates perforated by elongated holes of size 4  12 mm (the first configuration), the martensitic high-hardness Mars® 300P steel plates perforated by circular holes with a diameter of 5 mm (in the second configuration); and in the third configuration, the martensitic Mars® 300 plates perforated by oblong holes (4  10 mm) were used. The performed impact tests proved that the tested add-on plates assured high protection against the impact of 7.62  51 .308 Win P80 hard-core armour piercing (AP) projectiles. It was also observed that the plates caused similar mechanisms of bullet failure.

Design, Simulation and Testing of Overpack Encapsulation Vessels

2012 ◽  
Author(s):  
A. Towse ◽  
J. Dodds
Keyword(s):  
Pressure Vessel ◽  
High Speed ◽  
Failure Modes ◽  
Inner Product ◽  
Central Position ◽  
Video Footage ◽  
Rule Approach ◽  
The Moment ◽  
Explicit Dynamic ◽  
The Impact

The paper presents an overpack designed to contain nuclear product cans which may become pressurised or contaminated. The overpack provides a protective barrier to an inner product can, and due to the possibility of leakage of gas from the contents, the overpack must also function as a pressure vessel. Furthermore, the overpack is required to provide physical protection to the inner can and proof of containment was therefore necessary under a number of different impact scenarios, both pre-pressurised and also with the simulation of pressurisation at the moment of impact. Additionally, the inner product can was to be maintained in a central position during the deceleration at impact. This paper focuses on the analytical design and substantiation of the impact of the system which was performed using an explicit dynamic solver for a number of impact orientations. The design of the overpack to satisfy the relevant pressure vessel Code are not discussed in detail. The potential failure modes of the overpack during impact were assessed and design improvements made over a number of iterations. Following completion of the design and simulation phase, prototypes were built and tested to verify the engineering design and analysis. The testing showed that simulation driven design in conjunction with a pressure vessel design by rule approach was successful in creating a solution for the product can encapsulation. A comparison between the analytical simulation and high-speed video footage of the testing was also made.

Optimizing Electrical Protection for Medium Voltage Controller Lineup to Improve Liquids Pipelines Operation Reliability and Safety

2018 ◽  
Author(s):  
Ting Yu ◽  
Tushar Chaitanya
Keyword(s):  
Proximity Effect ◽  
Incident Energy ◽  
High Speed ◽  
Large Scale ◽  
Failure Modes ◽  
Partial Discharge ◽  
Light Detection ◽  
Medium Voltage ◽  
Voltage Controller ◽  
The Impact

MV (Medium Voltage) controller lineup electrical protection is crucial in protecting the equipment from large scale damage upon the occurrence of an electrical fault, reducing the time to restore power, thereby minimizing the impact to liquids pipelines operation. The paper discusses typical electrical failure modes that may occur in MV controller lineups, and demonstrates practical relaying engineering techniques that enable fast and effective fault clearing. Electrical faults in the MV controller lineup are often arcing type, commonly involve ground. Mitigating arc hazards in MV Class E2 controller lineups has traditionally been challenging without sacrificing the protection selectivity. As the paper demonstrates, a relaying scheme with the combined use of high-speed light-sensing and overcurrent detection will effectively mitigate the incident energy, while maintaining the protection selectivity for non-arcing overcurrent events. For new MV controller lineups, in addition to the “high-speed light detection and fault interruption”, zone-selective interlocking (ZSI) can also be a practical solution in improving relay protection speed, thus reduce the chance of severe arc flash occurrences. ZSI is particularly effective for fault occurrences on the line side of the phase CTs, busways or main incoming circuits. The ZSI scheme can be implemented on both Class E2 and circuit breaker (VCB) type MV controller lineups, however, with slightly different trip logic due to the limited fault clearing capability of the contactor. Although there are multiple contributing factors, the direct causes of electrical failures in MV controller lineup are commonly related to improper power cable installation and handling, potentially leading to premature insulation breakdown due mainly to the proximity effect and/or partial discharge. Inadequate cable separation and prolonged fault trip delay can increase the possibility of arcing fault occurrence. This can usually be mitigated through appropriate cable spacing, adequate conductor insulation, and optimized fault detection schemes. The paper provides overviews of the mechanisms of proximity effect and partial discharge propagation, and the modern relaying approaches for accurate fault type discrimination and facilitating fast fault interruption. Two case studies are provided in the paper as an aid in understanding the electrical fault mechanism originated from cable insulation failure, demonstrating the incident energy reduction before and after the implementation of high-speed light detection and fault interruption solutions on an existing MV controller lineup.

scholarly journals Dynamic damage in carbon-fibre composites

2016 ◽  
Vol 374 (2071) ◽  
pp. 20160018 ◽  
Author(s):  
N. K. Bourne ◽  
S. Parry ◽  
D. Townsend ◽  
P. J. Withers ◽  
C. Soutis ◽  
...  
Keyword(s):  
Carbon Fibre ◽  
High Speed ◽  
Failure Modes ◽  
Structural Integrity ◽  
High Speed Photography ◽  
Compression Phase ◽  
Impact Surface ◽  
Fibre Composites ◽  
The Impact ◽  
Carbon Fibre Composites

The Taylor test is used to determine damage evolution in carbon-fibre composites across a range of strain rates. The hierarchy of damage across the scales is key in determining the suite of operating mechanisms and high-speed diagnostics are used to determine states during dynamic loading. Experiments record the test response as a function of the orientation of the cylinder cut from the engineered multi-ply composite with high-speed photography and post-mortem target examination. The ensuing damage occurs during the shock compression phase but three other tensile loading modes operate during the test and these are explored. Experiment has shown that ply orientations respond to two components of release; longitudinal and radial as well as the hoop stresses generated in inelastic flow at the impact surface. The test is a discriminant not only of damage thresholds but of local failure modes and their kinetics. This article is part of the themed issue ‘Multiscale modelling of the structural integrity of composite materials’.

The brittle fracture of solids by liquid impact, by solid impact, and by shock

1964 ◽  
Vol 282 (1390) ◽  
pp. 331-352 ◽  
Keyword(s):  
Surface Wave ◽  
High Velocity ◽  
High Speed ◽  
Turbine Blades ◽  
Explosive Loading ◽  
Back Surface ◽  
High Speed Photography ◽  
Liquid Mass ◽  
Liquid Impact ◽  
The Impact

The type of stress pulse produced when a liquid mass strikes a solid at high velocity is first examined. Compressible behaviour, giving rise to a sharp peak of pressure, is found to occur in the initial stages of the impact. The duration of this peak depends on the dimensions and impact velocity of the liquid mass, and also on the compressible wave velocity for the liquid. A comparison is made with pulses produced by solid/solid impact and by the detonation of small quantities of explosive. Both the high-speed liquid impact and the explosive loading give intense pulses of duration only a few microseconds. A solid/solid impact has, by comparison, a much longer impact time of the order of hundreds of microseconds. The fracture of glasses and hard polymers using these three types of loading is described. The development of fracture is followed by high-speed photography. Differences in the modes of fracture are attributed to variations in the shape and duration of the applied stress pulses. Short circumferential fractures produced around the loaded area in liquid impact and explosive loading are shown to be initiated by the Rayleigh surface wave at points where flaws existed. More complex fracture patterns on the front surfaces of plates are due to the reinforcement of the surface wave with components of stress waves reflected from the back surface. A combination of impact loading and etching makes it possible to investigate the distribution and depths of flaws, their role in the fracture process, and the effect which etching has upon them. The observation on the deformation produced in solids by liquid impact has practical significance in the problem of supersonic aircraft flying through rain and in the erosion of turbine blades moving at high velocity through wet steam.

Experimental Study on the Response Characteristics of Oilcans under High-Velocity Fragment Impact

2012 ◽  
Vol 510 ◽  
pp. 500-506
Author(s):  
Chang Hai Chen ◽  
Xi Zhu ◽  
Hai Liang Hou ◽  
Li Jun Zhang ◽  
Ting Tang
Keyword(s):  
Experimental Study ◽  
High Velocity ◽  
High Speed ◽  
Room Temperature ◽  
Experimental Results ◽  
Fuel Oil ◽  
High Speed Camera ◽  
Response Characteristics ◽  
Fuel Oils ◽  
The Impact

To explore the deflagration possibility of the warship cabin filled with fuel oil under impact of high-speed fragments in the condition of room temperature, experiments were carried out employing the small aluminium oilcans filled with fuel oil. Response processes of the oilcans were observed with the help of a high-speed camera. The disintegration as well as flying scattering of the oilcans were analyzed. The reasons for atomization of the fuel oils were presented. Finally, the deflagration possibility of warship oil cabin was analyzed. Results show that the pressure inside the oilcan is quite great under the impact of the high-speed fragment, which makes the oilcan disintegration and flying scattering. Simultaneously, fuel oils inside the oilcans are atomized quickly followed by ejected in front and back directions. Under the same condition as in present tests, deflagration will not occur for fuel oils used by warships. Experimental results will provide valuable references for the deflagration analysis of warship fuel oil cabins subjected to the impact of high-velocity fragments.

scholarly journals A numerical study of projectile impact on thin aluminium plates

2009 ◽  
Vol 223 (11) ◽  
pp. 2519-2530 ◽  
Author(s):  
M Raguraman ◽  
A Deb ◽  
G Jagadeesh
Keyword(s):  
High Speed ◽  
Failure Modes ◽  
Numerical Study ◽  
Impact Testing ◽  
Good Prediction ◽  
Residual Velocity ◽  
Shell Elements ◽  
Simulation Based ◽  
Mesh Density ◽  
The Impact

This article deals with a simulation-based study of the impact of projectiles on thin aluminium plates using LS-DYNA by modelling plates with shell elements and projectiles with solid elements. In order to establish the required modelling criterion in terms of element size for aluminium plates, a convergence study of residual velocity has been carried out by varying mesh density in the impact zone. Using the preferred material and meshing criteria arrived at here, extremely good prediction of test residual velocities and ballistic limits given by Gupta et al. (2001) for thin aluminium plates has been obtained. The simulation-based pattern of failure with localized bulging and jagged edge of perforation is similar to the perforation with petalling seen in tests. A number of simulation-based parametric studies have been carried out and results consistent with published test data have been obtained. Despite the robust correlation achieved against published experimental results, it would be prudent to conduct one's own experiments, for a final correlation via the present modelling procedure and analysis with the explicit LS-DYNA 970 solver. Hence, a sophisticated ballistic impact testing facility and a high-speed camera have been used to conduct additional tests on grade 1100 aluminium plates of 1 mm thickness with projectiles of four different nose shapes. Finally, using the developed numerical simulation procedure, an excellent correlation of residual velocity and failure modes with the corresponding test results has been obtained.

Simulation study on the performance of time-over-threshold based positioning in monolithic PET detectors

2021 ◽  
Author(s):  
Charlotte Thyssen ◽  
Karel Deprez ◽  
Pieter Mollet ◽  
Roel Van Holen ◽  
Stefaan Vandenberghe
Keyword(s):  
High Speed ◽  
Threshold Value ◽  
High Accuracy ◽  
Nearest Neighbour ◽  
Pixel Size ◽  
Photodetector Array ◽  
Novel Approach ◽  
Pet Detectors ◽  
The Impact ◽  
Energy Determination

Abstract The vast majority of PET detectors in the field today is based on pixelated scintillators. Yet, the resolution of this type of detector is limited by the pixel size. To overcome this limitation one can use monolithic detectors. However, this detector architecture demands specific and high-speed detector readout of the photodetector array. A commonly used approach is to integrate the current pulses generated by every pixel but such circuitry quickly becomes bulky, power consuming and expensive. The objective of this work is to investigate a novel readout and event positioning scheme for monolithic PET detectors, based on Time-over-Threshold (ToT). In this case, we measure the time that the pulse is above a certain threshold through a comparator. The pulse widths are used for event positioning using a mean nearest neighbour approach (mNNToT). For energy determination one integrating multiplexed channel is foreseen. We evaluate the positioning accuracy and uniformity of such a ToT detector by means of Monte Carlo simulations. The impact of the threshold value is investigated and the results are compared to a detector using mean nearest neighbour with pulse-integration (mNNint), which has already proven to allow sub-mm resolution. We show minimal degradation in spatial resolution and bias performance compared to mNNint. The highest threshold results in the worst resolution performance but degradation remains below 0.1 mm. Bias is largely constant over different thresholds for mNNToT and close to identical to mNNint. Furthermore we show that Time-over-Threshold performs well in terms of detector uniformity and that scattered photons can be positioned inside the crystal with high accuracy. We conclude from this work that ToT is a valuable alternative to pulse-integration for monolithic PET detectors. This novel approach has an impact on PET detector development since it has the advantage of lower power consumption, compactness and inherent amplitude-to-time conversion.

Improvement of Energy Absorption of Circular Tubes Subjected to High Velocity Impact

2014 ◽  
Vol 566 ◽  
pp. 575-580
Author(s):  
Masahiro Higuchi ◽  
Shun Suzuki ◽  
Tadaharu Adachi ◽  
Hiroshi Tachiya
Keyword(s):  
Dynamic Behavior ◽  
High Velocity ◽  
Peak Load ◽  
Compressive Deformation ◽  
Straight Tube ◽  
Absorbed Energy ◽  
Velocity Impact ◽  
High Velocity Impacts ◽  
Fixed End ◽  
The Impact

The dynamic behavior of circular straight and stepped tubes made of aluminum alloy under high-velocity impacts was investigated by performing finite element analyses (FEA) and an experiment. The FEA and experiment on the straight tubes suggested that while an increase in the impact velocity enhanced the absorbed energy through compressive deformation just after impact, the peak load at the fixed end was not affected by the velocity. A stepped tube that was thicker near the impacted end was designed on the basis of the results for the straight tubes, and its dynamic behavior was investigated through FEA. The stepped tube absorbed a large amount of impact energy through compressive deformation at the thicker portion during the higher-velocity impact, without increasing the maximum fixed-end load from that of the straight tube.

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