scholarly journals Effect of Corundum and Basalt Aggregates on the Ballistic Resistance of UHP-SFRC

Crystals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1529
Author(s):  
Michal Mára ◽  
Přemysl Kheml ◽  
Kristýna Carrera ◽  
Jindřich Fornůsek ◽  
Radoslav Sovják
Keyword(s):  
High Performance ◽  
Mechanical Energy ◽  
3D Scanner ◽  
Depth Of Penetration ◽  
Steel Fibre Reinforced Concrete ◽  
Ballistic Resistance ◽  
Advanced Composite ◽  
Steel Core ◽  
Full Metal Jacket ◽  
Positive Effect

Ultra-high-performance steel-fibre-reinforced concrete (UHP-SFRC) is a technologically advanced composite with a high ability to absorb and dissipate mechanical energy. This work investigates the possibility of increasing ballistic resistance by adding different percentages of corundum and basalt aggregate into this type of concrete. The most common type of ammunition, a 7.62 mm × 39 mm calibre with a full-metal jacket and a mild-steel core (FMJ-MSC), was used to test all samples. The size of the damage and the mode of failure were determined using a 3D scanner operating on the principle of photogrammetry. The experimental campaign showed that the addition of basalt and, especially, corundum aggregate has a positive effect on ballistic resistance. In particular, the increase in compressive strength and the slight decrease in depth of penetration (DOP) was observed in the case of the usage of the corundum aggregate.

scholarly journals INFLUENCE OF CORUNDUM AS COARSE AGGREGATE IN HIGH-PERFORMANCE CONCRETE ON PROJECTILE IMPACT RESISTANCE

2019 ◽  
Vol 22 ◽  
pp. 62-66
Author(s):  
Michal Mára ◽  
Zdeňka Říhová ◽  
Markéta Kočová
Keyword(s):  
High Performance ◽  
Coarse Aggregate ◽  
High Performance Concrete ◽  
Impact Resistance ◽  
3D Scanner ◽  
Depth Of Penetration ◽  
Projectile Impact ◽  
Steel Fibre Reinforced Concrete ◽  
Coarse Aggregates ◽  
Different Types

The aim of this paper is focused on the influence of corundum as coarse aggregate in high-performance concrete on projectile impact resistance in terms of depth of penetration and size of the crater. Based on the experimental programme, samples of high-performance steel-fibre-reinforced concrete with different types and quantities of coarse aggregates were designed and produced, to be subjected to impact loading in the form of projectile impact. Damaged samples were scanned using a 3D scanner and their surface was evaluated. The goal of the paper was to find the optimum content of coarse aggregate in the mixture in order to improve its resistance against projectile impact.

Field Tests of Cementitious Composites Suitable for Protective Structures and Critical Infrastructure

2016 ◽  
Vol 722 ◽  
pp. 3-11 ◽  
Author(s):  
Jiří Štoller ◽  
Petr Dvořák
Keyword(s):  
Reinforced Concrete ◽  
High Performance ◽  
Critical Infrastructure ◽  
Field Tests ◽  
Plain Concrete ◽  
Cementitious Composites ◽  
Fibre Reinforced Concrete ◽  
Steel Fibre Reinforced Concrete ◽  
Ballistic Resistance ◽  
Protective Structures

The paper deals with field tests of cementitious composites suitable for protective structures and critical infrastructure. The tests of ballistic resistance against contact and distant explosions are performed according to the NATO standards. The results of tests of plain concrete, steel fibre reinforced concrete and high performance fibre reinforced concrete are analysed.

scholarly journals Determination of ballistic resistance of cementitious composites

2021 ◽  
Vol 1205 (1) ◽  
pp. 012013
Author(s):  
J Vojtisek ◽  
E Bystrianska ◽  
O Koutny ◽  
J Kratochvil ◽  
M Drdlova
Keyword(s):  
High Performance ◽  
Ceramic Materials ◽  
Cementitious Composites ◽  
Cement Composites ◽  
Penetration Test ◽  
Depth Of Penetration ◽  
Ballistic Resistance ◽  
Differential Efficiency ◽  
The Relationship

Abstract 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.

Effect of Compensation and Work Environment on Employee Performance with Employee Job Satisfaction as an Intervening Variable

2018 ◽  
Vol 9 (03) ◽  
pp. 20553-20562
Author(s):  
Putu Ayu Diah Juliarti ◽  
Anak Agung Putu Agung ◽  
I Nengah Sudja
Keyword(s):  
Job Satisfaction ◽  
Work Environment ◽  
High Performance ◽  
Employee Performance ◽  
Statistical Tests ◽  
Path Coefficient ◽  
Significant Positive Effect ◽  
Organizational Goals ◽  
Record Keeping ◽  
Positive Effect

An employee who has a high performance and better able to support the achievement of the goals and objectives set by the company. Employees can work well if you have a high performance that can produce good work anyway. With the high- performance that employees, is expected to achieve organizational goals. This study examines the effect of compensation and work environment on employee performance with job satisfaction to be intervening variable. Data on compensation, work environment, job satisfaction, and employee performance obtained through observation, record keeping and questioner with respondents. The data obtained are then analyzed using Partial Least Squares (PLS). Statistical tests results showed  (1) the compensation proved significant positive effect on job satisfaction the path coefficient of 0.434 and T-Stats for 4.880, (2) work environment proved to be a significant positive effect on job satisfaction the path coefficient of 0.434 and T-Stats for 4.074, (3) job satisfaction proved to be a significant positive effect on employee performance the path coefficient of 0.264 and T-Stats for 2.458, (4) compensation proved positive and significant effect employee performance the path coefficient of 0.242 and T-Stats for 2.912, (5) work environment proved positive and significant effect employee performance the path coefficient of 0.378 and T-Stats for 3.343. Based on test results obtained statistical results of all variables positive and signicant impact.

scholarly journals Cooling Performance Analysis of Outside Fins of the Closed Circuit Axial Piston Transmission

Machines ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 17
Author(s):  
Chen Yang ◽  
Long-jie Yu ◽  
Junhui Zhang ◽  
Jin-yuan Qian
Keyword(s):  
Heat Transfer ◽  
Heat Dissipation ◽  
Mechanical Energy ◽  
Closed Circuit ◽  
Moderate Increase ◽  
Frictional Loss ◽  
Fin Thickness ◽  
Axial Piston ◽  
Positive Effect ◽  
Peak Value

Realizing conversion between fluid power and mechanical energy, the closed circuit axial piston transmission (CCAPT) plays a vital and indispensable role in miscellaneous industries. The frictional loss and leakage loss inside the system give rise to the inevitable temperature rise. In order to prolong the life of the device, a cooling structure on the outside of the CCAPT is designed for promoting heat dissipation. Based on the relevant heat transfer law and the temperature distribution of internal machinery elements, a spiral fin structure is designed at the shell side. With the help of numerical simulation, the effects of fin height, fin pitch, and fin thickness on the thermal performance are studied. The flow field and temperature field on the outside of the fin structure are obtained as a guidance for enhancing heat dissipation effect. Results indicate that the area of rotating elements tend to accumulate heat, where more attention should be paid for a better cooling effect. In addition to this, a moderate increase of fin height, fin pitch and fin thickness has a positive effect on heat transfer enhancement. The peak value of Nusselt number is obtained with a fin height of 7.5 mm, which is about 2.09 times that of the condition without the fin structure. An increase in fin pitch improves both heat transfer performance and comprehensive performance at the same. When fin pitch is 30 mm, Nusselt numberincreases 104% over the original condition.

scholarly journals Resistance of an Optimized Ultra-High Performance Fiber Reinforced Concrete to Projectile Impact

Buildings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 63
Author(s):  
Anna L. Mina ◽  
Michael F. Petrou ◽  
Konstantinos G. Trezos
Keyword(s):  
Reinforced Concrete ◽  
High Performance ◽  
High Performance Concrete ◽  
High Strength ◽  
Fiber Reinforced Concrete ◽  
Steel Fibers ◽  
Fiber Reinforced ◽  
Depth Of Penetration ◽  
Projectile Impact ◽  
High Performance Fiber

The scope of this paper is to investigate the performance of ultra-high performance fiber reinforced concrete (UHPFRC) concrete slabs, under projectile impact. Mixture performance under impact loading was examined using bullets with 7.62 mm diameter and initial velocity 800 m/s. The UHPFRC, used in this study, consists of a combination of steel fibers of two lengths: 6 mm and 13 mm with the same diameter of 0.16 mm. Six composition mixtures were tested, four UHPFRC, one ultra-high performance concrete (UHPC), without steel fibers, and high strength concrete (HSC). Slabs with thicknesses of 15, 30, 50, and 70 mm were produced and subjected to real shotgun fire in the field. Penetration depth, material volume loss, and crater diameter were measured and analyzed. The test results show that the mixture with a combination of 3% 6 mm and 3% of 13 mm length of steel fibers exhibited the best resistance to projectile impact and only the slabs with 15 mm thickness had perforation. Empirical models that predict the depth of penetration were compared with the experimental results. This material can be used as an overlay to buildings or to construct small precast structures.

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