Depth Of Penetration Test Research Articles

Properties and ballistic tests of strong B4C-TiB2 composites densified by gas pressure sintering

B4C-TiB2 composites with classical 75/25 vol ratio were sintered by pressureless sintering with and without gas pressure application in the final stage of densification, using a novel prototypal furnace. A small fraction of WC was introduced through high energy milling of the starting powders with WC-Co spheres. High energy milling facilitated the densification thanks to incorporation of WC impurities acting as sintering aid, and size reduction of the starting powders. Strength, stiffness and toughness of the ceramic densified at 2050 °C via gas pressure sintering were even better than hot pressed composites at 1900 °C. Depth of Penetration tests on plates with 3–5 mm thickness demonstrated that the gas pressure sintered material had a superior performance compared to the hot pressed one. This work also revealed that hardness was not the property spotting the best ballistic performance.

Determination of ballistic resistance of cementitious composites

The paper describes the possibility of using the DOP test, standardly used to evaluate the ballistic resistance of ceramics, to determine the ballistic resistance of cement composites. DOP - Depth of penetration test - is based on measurement of residual penetration of projectile in witness system after the sample perforation; this parameter is used to determine differential efficiency factor (DEF), characterizing the ballistic resistance of the particular material. To verify the method for non-ceramic materials, four variants of cementitious composites with compressive strengths in the range of 30–150 MPa have been tested. The obtained results confirm the method’s suitability for determining the ballistic resistance of cement composites in terms of ease of implementation, sensitivity, and accuracy of the obtained results for both composites of common strengths and high-performance variants. The paper also discusses some aspects of the relationship between the mechanical parameters of cement composites under static loading and their ballistic resistance.

The ballistic impact performance of nanocrystalline zirconia-toughened alumina (nZTA) and alumina ceramics

The ballistic impact performance of nanocrystalline zirconia-toughened alumina (nZTA) ceramics, comprising 15 wt% nano-yttria-stabilised zirconia in a sub-micron alumina matrix, have been studied through depth of penetration tests and compared to the results for monolithic alumina. The penetration resistance of each material was evaluated by fitting the penetration depth results against the thickness of the ceramic targets. These results show that, despite micro-Raman analysis of the nZTA confirming the occurrence of the classic tetragonal-to-monoclinic zirconia phase transformation, nZTA ceramics provide no benefit with respects to penetration resistance compared to monolithic alumina. Analysis of the fragments generated using Cr3+/Al2O3 fluorescence spectroscopy shows that both the nZTA and alumina experience similar amounts of plastic deformation as a function of fragment size, with finer fragments (<150 μm) exhibiting more plastic deformation than coarser fragments (>150 μm). These results are validated through fracture surface observations and subsurface dislocation analysis using SEM and TEM respectively.

Effect of MgO·Al2O3·SiO2 glass-ceramic as sintering aid on properties of alumina armors

Liquid-phase sintering is advantageous compared to solid-state sintering in manufacturing ceramic composites including lightweight armors. The crystalline phases formed from the liquid phase affect the mechanical properties of the material, and thus, to the best of our knowledge, their effect on the ballistic behavior need to be understood. In this paper, the correlation between mechanical properties and ballistic performance of non-stoichiometric cordierite-based glass-ceramic/alumina composites arrays with 99.8% purity was evaluated. The precursor alumina had average particle sizes of 0.5 and 1.7 μm, and the added glass-ceramic contents were 7 and 14 vol%. Cold-pressed samples were sintered under conditions of maximum densification. The behavior of each composition was compared with that of pure alumina with respect to sintering, mechanical properties, and ballistic performance evaluated by depth of penetration (DOP). For a single precursor alumina, decreases in ballistic resistance were observed with increases in the content of glass-ceramic due to the reduction in mechanical properties, specially hardness and Young's modulus (E). The overall analysis of the data indicated that ballistic behavior of alumina is more complex, and the toughness (KIC) and hardness (HK) can be regarded as predictive properties for determining alumina ballistic performance in DOP test. It is demonstrated that glass-ceramic addition lead to lower sintering time and temperature, from 1670 °C for 5 h to 1570 °C for 0.5 h, and these compositions have the similar areal density of pure alumina regarding ballistic performance, with less than 4% difference between 1.7 μm pure alumina and the composition with 7 vol% glass-ceramic precursor addition.

Fabrication of AA7005/TiB2-B4C surface composite by friction stir processing: Evaluation of ballistic behaviour

The present work aims to enhance the ballistic resistance of AA7005 alloy by incorporating the TiB2 and B4C ceramic reinforcement particles. Surface composites with different weight fractions of TiB2 and B4C particles were processed by friction stir processing. Micro-hardness and depth of penetration tests were carried out to evaluate the ballistic properties of the surface composites. The surface hardness of the composite was found to be nearly 70 HV higher than base alloy. The depth of penetration of the steel projectile was 20–26 mm in the composites as compared to 37 mm in the base alloy. Ballistic mass efficiency factor of the surface composite was found to be 1.6 times higher than base alloy. This is mainly attributed to the dispersion strengthening from the reinforcement particles.

Considerations on Dop (Depth Of Penetration) Test for Evaluation of Ceramics Materials Used in Ballistic Protection

AbstractTremendous amount of funds and other resorces were invested in studying the response of ceramic materials under ballistic impact, the main goal being to find a way to increase the protection of soldiers and the vehicles used in the modern battlespace. Using of ceramic materials especially carbon based (carbides), nitrogen based (nitrides) and oxygen based (oxides) ceramics in order to increase the protection level of ballistic equipment could be, sometimes, a big challenge when trying to use the proper test in order to evaluate and compare their performances. The role of the tests is to provide a better understanding of their response in different situations and, as a consequence, to make them more efficient as armour components through future improvements. The paper presents shortly the main tests which are used and eventually standardised for evaluating the ballistic behaviour of the ceramics and other armour components, with a special focus to DOP (Depth of Penetration) Tests.

Ballistic performance evaluation of ceramic tiles with respect to projectile velocity against hard steel projectile using DOP test

The effect of backing material, projectile velocity and tile thickness on the ballistic efficiency of ceramic materials was studied against 7.62 mm AP projectile in depth of penetration (DOP) test configuration. An analysis on variation in differential efficiency factor (DEF) with respect to backing material was carried out. The factor responsible for variation in DEF was eliminated using a normalization method. A new definition (NDEF/ NBE) is proposed for calculation of ballistic efficiency. Using the new definition a comparison of ballistic efficiency of hot pressed boron carbide, alumina and zirconia toughened alumina were done for different projectile velocities and tile thickness. The DEF was found to increase with increase in projectile velocity, but NDEF and NBE were found to decrease with increase in projectile velocities. Even though the DEF, NDEF and NBE have produced different ballistic efficiencies they all have produced similar trends with respect to tile thickness.

Effect of Ceramic Properties and Depth-of-penetration Test Parameters on the Ballistic Performance of Armour Ceramics

&lt;p&gt;Through an analysis on the relationship among ceramic properties, the depth of penetration (DOP) test parameters and the ballistic performance of armour ceramics based on literatures, the effects of ceramic type, tile thickness and projectile velocity on the ballistic performance of different kinds of ceramics were investigated systematically. The results show that the ballistic performance of different armour ceramics mainly depends on its density, and by using thin ceramic tiles or under high velocity impact, the ceramic composite armour could not provide effective ballistic protection. Furthermore, the differences in the ballistic performance of armour ceramic are found due to the different ballistic performance criteria and DOP test conditions. Additionally, the slope of the depth of penetration (not include tile thickness) (Pa) versus tile thickness has negative correlation with flexural strength of ceramics, indicating the flexural strength can be one of the criteria to evaluate the performance of armour ceramics.&lt;/p&gt;

An Examination of DOP Test of Ceramic Tile Subjected to Long Rod Penetration

Depth of penetration (DOP) test of ceramic tile subjected to long rod impact was analyzed by applying the Tate model. This paper investigated the influence of impact velocity and tile thickness on the ballistic performance measurement of the tested ceramic tiles. DOP test was simplified as an eroding rod penetrating a target composed of multilayered materials. Through applying the Tate model, the method of obtaining the numerical solution was proposed. For a constant impact velocity, it was found that the measured differential tile efficiency (DEF) was independent of the thickness of the ceramics tiles. But the measured DEF decreased as the impact velocity increased. These analytical conclusions were verified by the using of the results of DOP tests of SiC and Al2O3 tiles subjected to impact of long tungsten alloy rods at a nominal impact velocity of 1.3 km/s.

Effects of Specimen Size and Boundary Conditions on the Penetration Depth of Metal Ceramic Structure

Ceramics has high hardness but low density and has been used in defense to enhance the protection of human bodies or vehicles against projectile penetration. Ceramics can defeat a ballistic threat by deforming and fracturing a metal projectile, thus eliminate or reduce the depth of penetration in backing steel. This study investigates the penetration progress of a tungsten alloy projectile into an Al2O3 ceramics (alumina) backed with high strength steel 4340. Depth of penetration tests were conducted on ceramics/steel specimens by WNiFe projectiles at impact speeds around 1280m/s. Numerical simulations corresponding to the test configurations were carried out using commercial software (Autodyn) and the prediction of crater profile coincides with experimental results. Further simulations investigated the effects of specimen size and boundary conditions on the total depth of penetration; the performance of metal ceramic structure against ballistic penetration was explored and evaluated.

Using Depth-of-Penetration Tests to Design Transparent Armor

The depth-of-penetration (DOP) test has been modified for application to transparent armor materials. Armor materials to be tested are bonded to a polycarbonate substrate and penetration into the substrate measured. The tests can be used both for comparing armor materials and for evaluating laminate parameters. Materials tested were all armor-grade transparencies: borosilicate glass, soda-lime glass, glass ceramic, and spinel. For blunt projectiles, armor material performance is inversely correlated with density. For hard, sharp projectiles, material strength is most important, with spinel providing the best performance. The efficiency of spinel-glass laminates was only weakly dependent on the spinel thickness. Linear scaling can reconcile data obtained with different size projectiles. Relatively thick bond layers do not adversely affect the efficiency of laminates. DOP tests can be used to evaluate effects of damage from single cracks and multiple hits, and results also provide an estimate of optimal armor design against the threat used in the DOP experiments.

Influence of Material Properties on the Ballistic Performance of Ceramics for Personal Body Armour

In support of improved personal armour development, depth of penetration tests have been conducted on four different ceramic materials including alumina, modified alumina, silicon carbide and boron carbide. These experiments consisted of impacting ceramic tiles bonded to aluminum cylinders with 0.50 caliber armour piercing projectiles. The results are presented in terms of ballistic efficiency, and the validity of using ballistic efficiency as a measure of ceramic performance was examined. In addition, the correlation between ballistic performance and ceramic material properties, such as elastic modulus, hardness, spall strength and Hugoniot Elastic Limit, has been considered.

The influence of experimental design on depth-of-penetration (DOP) test results and derived ballistic efficiencies

Experimental data for ceramic armor materials from two test methods, small-scale reverse ballistic tests and depth-of-penetration (DOP) tests, are reviewed and compared. Results from reverse ballistic tests can be used to estimate the length of rod erosion in the ceramic tiles of DOP tests. The outcome of a given DOP test can then be predicted by using recently published data bases on RHA penetration to determine the residual penetration into the steel back-up of the DOP test. Results of this methodology, compared to experimental DOP-test results, agree reasonably well for aluminum nitride and silicon carbide, even though scale sizes, impact velocities and experimental procedures varied considerably between investigators. The methodology was then applied to single-valued performance criteria for ceramic armor materials, for example, mass efficiency. This analysis demonstrates that in certain cases, test parameters, like the ratio of penetrator length to ceramic tile thickness, affect test results considerably more than differences between ceramic types. Thus, DOP tests must be properly designed and interpreted in order to assess correctly the ballistic performance of ceramics.

Hypervelocity penetration of tungsten sinter-alloy rods into aluminum

The penetration of tungsten sinter-alloy rods having length-to-diameter ratios of L/D= 10 and 12.5 into alumina targets was investigated in the velocity range vp= 1.25 to 3km/s. The depth of penetration (DOP) test and the time resolved oberservation using a 600 kV flash X-ray system were applied to assess the protection efficiency of the ceramics. From DOP tests, the residual penetration into a steel backing yields the differential efficiency factor DEF and the mass efficiency factor MEF. DEF increases with vp; MEF decreases. On the other hand, DEF decreases as ceramic thickness increases; MEF increases and converges to DEF for residual penetration zero. From the time resolved measurements, position and length reduction of the rod during penetration in the ceramics were obtained. The process can be described by Tate's fluid jet model in good approximation. The target resistance parameter R, defined in the modified Bernoulli equation, characterizes the ceramic performance. The average R values are 5.4, 6.1 and 4.8 GPa at impact velocities vp= 1.7, 2.5 and 3km/s, respectively, i.e. there is no strong dependence of R on vp.

Penetration of hard layers by hypervelocity rod projectiles

The penetration resistance of hard layers, such as ceramics and hardened steels, struck by high velocity long rod projectiles can be characterized by the depth of penetration (DOP) test. The DOP test can be used to calculate average penetration resistance, which can be expressed as R T. The tests can also be used to compute differential efficiency. For hard materials, these values differ markedly from those for conventional armor steel (RHA). Implications for the effectiveness of hypervelocity penetrators are that the optimum velocity for energy efficient penetration will be much higher for hard materials than for RHA. Furthermore, ceramics will continue to substantially outperform armor steels, while high hardness steels will lose their relative advantages against long rod projectiles above 3 km/s.