The welding of armour grade steel plays a vital role in combat vehicle structures. A work is conducted to investigate the effect of Water Jet (WJ) and Flame Cutting (FC) on the metallurgical and ...mechanical properties of the welded armour steel plates. The sustainable WJ machining shall produce the weld groove by a single pass without heat formation in the cut surface, which is unavoidable in the flame cutting process. The results demonstrate that the WJ weld plate is more desirable, as the martensite structure is obtained in different Heat-Affected Zones (HAZ). It is achieved by one-time heat involvement compared to ferrite – pearlite structure in HAZ of the flame cut weld plate. A higher hardness of 335 HV is observed in the fusion zone of the WJ weld plate compared to 212 HV in the flame cut weld plate. The tensile failure occurs in the fusion zone of both water jet and flame cut weld plates and the fusion zone has a higher impact strength of 108 J (8 times higher than base plate). Thus, implementing sustainable WJ machining in preparing the weld groove enhanced the welding properties in military-grade armour steel.
•Ability to achieve weld groove by a single pass cut in a water jet weld plate.•The ferrite-pearlite structure is identified in HAZ while using flame cut weld plate.•The martensite structure is obtained in HAZ while using water jet weld plate.•Enhancement in the mechanical properties in the fuzion zone through sustainable approach.
This research deals with the experimental and numerical investigation of ballistic protection provided by a combination of perforated and base armour plates. A 7.62mm armour piercing projectile was ...used during the experimentation to determine the ballistic response of an aluminum base armour plate and a combination of steel perforated and aluminum base armour plate. The armour piercing projectiles were able to penetrate the base armour plate while the combination of perforated and base armour plates was able to stop the penetration of the armour piercing projectile. A finite element method based numerical model was developed to investigate the defeating phenomenon of perforated and base armour plate combination. The brittle fracture caused by the bending of the projectile core due to the asymmetric impact was predicted and the resulting fragments of the projectile were unable to penetrate the base armour plate. Craters were formed on the surface of the base armour plate from the impact of the projectile fragments. The numerical model was able to predict the hole growth and penetration of projectile when only the base armour plate was impacted by the projectile.
•Novel procedure to verify modelling in terminal ballistics of steel armours.•Sufficient ballistic data with several bullet/plate interaction conditions.•Calibration of constitutive and failure ...models using optical methods.•3D modelling of bullet/target interaction using Solid and Solid/SPH conversion algorithm.•The methodology satisfactorily verified and evaluated the models and FE methods.
We present a novel methodology to experimentally verify constitutive models and numerical algorithms used in terminal ballistics of small arms ammunition. The methodology comprises of the following elements: identification of material models in a set of independent tests, terminal ballistics testing of conditions covering the most important cases of bullet–target interactions, while providing enough data to assess the scatter of parameters measured in the experiments and to create a measure characterising deviation of modelling results from the experiments. To meet the objectives of this study, 7.62mm armour-piercing ammunition was used to perforate steel armour plates at ordnance velocity. Several parameters that characterise bullet velocity and path, plate deformation and ductility were measured and used as reference data for the verification of models. Relatively complex and simple constitutive and failure models implemented in the Finite Elements (FE) code LS DYNA were used. Finally, solid Lagrange and hybrid solid/Sooth Particles Hydrodynamics (SPH) discretisation methods with detailed models of the bullet and target are presented and different findings are compared with ballistic test results. The methodology shows a significant efficiency in the assessment of the adequacy of models. In this study, stress triaxiality and strain rate based models were found to give results in good agreement with experimental results, and several physical mechanisms are well predicted.
This work investigated whether multiple freshwater populations of three‐spined stickleback Gasterosteus aculeatus in different freshwater catchments in the Jutland Peninsula, Denmark, derived from ...the same marine populations show repeated adaptive responses. A total of 327 G. aculeatus collected at 13 sampling locations were screened for genetic variation using a combination of 70 genes putatively under selection and 26 neutral genes along with a marker linked to the ectodysplasin gene (eda), which is strongly correlated with plate armour morphs in the species. A highly significant genetic differentiation was found that was higher among different freshwater samples than between marine–freshwater samples. Tests for selection between marine and freshwater populations showed a very low degree of parallelism and no single nucleotide polymorphism was detected as outlier in all freshwater–marine pairwise comparisons, including the eda. This suggests that G. aculeatus is not necessarily the prime example of parallel local adaptation suggested in much of the literature and that important exceptions exist (i.e. the Jutland Peninsula). While marine populations in the results described here showed a high phenotype–genotype correlation at eda, a low association was found for most of the freshwater populations. The most extreme case was found in the freshwater Lake Hald where all low‐plated phenotypes were either homozygotes for the allele supposed to be associated with completely plated morphs or heterozygotes, but none were homozygotes for the putative low‐plated allele. Re‐examination of data from seven G. aculeatus studies agrees in showing a high but partial association between phenotype–genotype at eda in G. aculeatus freshwater populations and that mismatches occur everywhere in the European regions studied (higher in some areas, i.e. Denmark). This is independent of the eda marker used.
The four types of dermal armour bones/osteoderms and scutes of Balochisauridae and Pakisauridae (Titanosauria) were found as fragmentary in the latest Cretaceous (Maastrichtian) Vitakri Formation of ...Sulaiman basin in Pakistan. Larger and smaller osteoderms from Pakistan provide a further opportunity for correlation with the armor bones already discovered from Madagascar, Argentina, Brazil, France, Malawi, Romania and Spain.
Five materials, copper (two versions), iron, and armour plate steel (two versions) have been tested at different strain-rates and temperatures. All tests were in compression. The materials were ...studied to provide experimental data for input into hydrocode models of armour behaviour by the Defence Research Agency, Fort Halstead. A wide selection of metals was examined so that comparisons could be drawn between modelling the behaviour of face centred and body centred cubic metals, and to carry out a broader investigation into how the results obtained were affected by the test methods. Experiments were performed at temperatures from -100°C to 20°C and mean plastic strain-rates from 10-3 to 103 S-l, using a Split Hopkinson Pressure Bar (SHPB) system for high strain-rates and a Hounsfield 50 kN machine for quasistatic conditions. The stress-strain behaviour of the materials as a function of temperature and strain-rate was then determined. The effects of interfacial friction on the measured compreSSlve properties of copper and the armour plate steels have been investigated. Since the coefficient of friction was the critical parameter, ring tests were carried out and the Avitzur analysis applied. In general, the coefficient of friction decreased with increasing strain-rate and temperature. The tested specimen's appearance indicated the same friction trends. Hydrocode modelling of the SHPB system produced corrections to the flow stress, to compensate for interfacial friction, that agree well with those predicted by the Avitzur analysis. Deformed finite element mesh plots analysed in conjunction with barrelled specimens have given a clearer insight into the mechanisms of interfacial friction. The Armstrong-Zerilli constitutive models have been applied to copper, iron and armour plate steel results corrected for thermal softening and specimen-platen interfacial friction. These models have been shown to provide a reasonable description of the materials' behaviour. The research investigation has shown that in order to obtain fundamental stressstrain behaviour of the materials, then corrections must be applied, which can be quite significant. These corrections must take into account the effects of material thermal softening and the specimen-platen interfacial friction.
This is a very timely review of body armour materials and systems since new test standards are currently being written, or reviewed, and new, innovative products released. Of greatest importance, ...however, is the recent evolution, and maturity, of the Ultra High Molecular Weight Polyethylene fibres enabling a completely new style of system to evolve – a stackable system of Hard Armour Plates. The science of body armour materials is quickly reviewed with emphasis upon current understanding of relevant energy-absorbing mechanisms in fibres, fabrics, polymeric laminates and ceramics. The trend in on-going developments in ballistic fibres is then reviewed, analysed and future projections offered. Weaknesses in some of the ceramic grades are highlighted as is the value of using cladding materials to improve the robustness, and multi-strike performance, of Hard Armour Plates. Finally, with the drive for lighter, and therefore smaller, soft armour systems for military personnel the challenges for armour designers are reported, and the importance of the relative size of the Hard Armour Plate to the Soft Armour Insert is strongly emphasised.
Defence can play a paramount role in military organization thus designing light weight armour capable of protecting target from lethal damage is important. While the traditional armour plated use ...high hardness steel but in recent development of advanced ceramics with low density and high strength properties have opened new door of possibilities in the field. The presented paper bring outs a study regarding protection efficiency of superposed sandwiched panel with metal matrix interface and honeycomb structures against ballistic impacts is performed. The authors have developed a composite armour plate with non-ricochet properties capable of taking resisting multiple projectiles, using ceramics Honey-comb structure tile glued together encased within metal matrix. Paper discusses experimental data, geometry of the experimental setup, modelling (meshing and initial conditions). Numerical analysis has been done on different metals, ceramics and polymers and the best among them are selected. The stacking sequence of the selected materials is developed using crashworthy design concepts. Design parameters for optimized sandwiched panel are provided and superposed sandwiched panel responses with metal matrix interface and honeycomb structures are assessed.
Introduction/purpose: The paper presents a numerical simulation of an impact of a 12.7 mm projectile on an armored metal plate with a velocity of 500 m/s at a distance of 900 m. Numerical simulations ...offer the possibility of drastically reducing the time required to obtain results in comparison to the time required for planning, organization and execution of experiments. The numerical simulation is done by variations in the thickness of the armor metal plate, specifically an armor metal plate of a thickness of 10 mm, 17 mm, 18 mm, and 23 mm. The mentioned armored plate thicknesses were chosen based on the results in order to determine the limit thickness of the armored plate for the projectile perforation limit, as well as for complete ballistic protection. Methods: Finite element modeling is used for analyzing stresses and deformations of the armored plates. The mentioned method calculates the impact of the projectile on the obstacle, precisely the collision of the projectile and the armor plate. Results: For the comparative analysis, the parameters used are the values of the stress and the displacement. For each of the above-mentioned thicknesses of the armored metal plate, the values of stress and displacement during projectile impact were determined. The results of this study show how the thickness of the armor plate affects the interaction of the projectile and the armor plate. Conclusion: If the physical and chemical characteristics of the armored plate remain unchanged, as the thickness of the armored plate increases, the possibility of projectile penetration decreases, and vice versa. This research is of essential importance because it analyzes the stresses and deformation of armor plates whose basic role is the protection of personnel and equipment from the projectile impact. In this regard, the thickness of the armored plate for semi-penetration of the projectile is determined.
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