Impact Resistance of Liquid Body Armor Utilizing Shear Thickening Fluids: A Computational Study

2015 ◽  
Author(s):  
Fardin Khalili ◽  
Federico De Paoli ◽  
Rasim Guldiken
Keyword(s):  
Multiphase Flow ◽  
High Speed ◽  
Volume Fraction ◽  
Computational Study ◽  
Shear Thickening ◽  
Ballistic Performance ◽  
High Quality ◽  
Liquid Body ◽  
Shear Thickening Fluids ◽  
The Impact

Since the creation of advanced knives and firearms with high rates of speed, safety has always been a vital issue for armed forces. A disadvantage of a regular fabric Kevlar is that, although it has an effective resistance against the impact of low-speed bullets, it reveals its weakness in the case of a stab wound and high-speed bullets. Under these circumstances, a new executable technology of fibers that improves the ballistic performance of the materials utilized in body armors is an essential necessity to build high quality and protective vests which are perfectly bulletproof. The purpose of this study is to investigate the physics and concepts of shear thickening fluids and perform a computational CFD simulation of liquid body armors which consist of a combination of polyethylene glycol liquid and nanoparticles of silica. A model of multiphase flow environment with STFKevlar, as a representative of the non-Newtonian shear thickening fluid (STF), is simulated in STAR-CCM+ in order to analyze the behavior of STFs under impact and performance of novel liquid body armors. In the current simulation, Eulerian multiphase flow and volume of fluid (VOF) are applied to generate three discrete regions and determine the volume fraction of each phase including gas, non-Newtonian liquid and solid which represent air, STFKevlar and bullet, respectively. Moreover, dynamic fluid body interactions (DFBI) and overset mesh are utilized to consider the interactions between the regions and forces applied. In this study, the properties of the bullet are based on characteristics of a regular pistol bullet, and it approaches the STFKevlar with the constant speed of 400 m/s. The results show that the non-Newtonian material is initially at equilibrium state and while the bullet approaches the STFKevlar, it acts like a shear thinning fluid. As a high-speed bullet nears the STFKevlar, it absorbs the significant amount of energy that is applied by the bullet. Consequently, the bullet stops penetrating the STFKevlar in a very small fraction of time due to the considerable increase in viscosity. As the shear rate increases over a certain critical value, viscosity increases remarkably which is the main characteristic of shear thickening transition and finally, it reaches to its maximum value of viscosity in approximately 8 × 10−5sec. In addition, a bullet applies a considerable amount of force on any Kevlar due to its high velocity and kinetic energy; however, the high resistant STFKevlar is approved as a high quality and protective vests which stops the bullet in 6 × 10−4sec.

Impact Tests in an Air-Water Mixture

2017 ◽  
Author(s):  
Aboulghit El Malki Alaoui
Keyword(s):  
High Speed ◽  
Volume Fraction ◽  
Optical Probe ◽  
Test Machine ◽  
Water Mixture ◽  
Air Bubble ◽  
Impact Tests ◽  
Void Fractions ◽  
Shock Test Machine ◽  
The Impact

Experimental impact tests were performed using a shock machine and aerated water by means of an air-bubble generator. High speed shock test machine allows carrying out tests of impact on water (slamming). This machine permits to stabilise velocity with a maximal error equal to 10% during slamming tests. The air volume fraction in the bubble was measured by optical probe technique. The present work is aimed at quantifying the effects of the aeration on the hydrodynamic loads and pressures during the entry of a rigid body at constant speed in an air-water mixture. The impact tests were conducted with a rigid pyramid for an impact velocity equal to 15 m.s−1 and for two average void fractions, 0,46% and 0,84%. The reduction of the impact force and pressure due to aeration has been confirmed by these experiments.

Numerical Study of High Velocity Impact onto MMC/Ceramic Layered Systems

2016 ◽  
Vol 715 ◽  
pp. 210-215
Author(s):  
Seung Hwan Lee ◽  
Minh Lee
Keyword(s):  
Mild Steel ◽  
Ceramic Tile ◽  
Volume Fraction ◽  
Numerical Study ◽  
Tungsten Alloy ◽  
Layered Systems ◽  
Depth Of Penetration ◽  
Ballistic Performance ◽  
Long Rod ◽  
The Impact

Metal Matrix Composites (MMCs) can be applied to military applications due to the light weight and the ballistic performance. In this study, a numerical simulation has been performed for the penetration of a long-rod penetrator into MMC/Ceramic layered systems. The impact velocity is 1.5km/s and the length to diameter (L/D) ratio is 10.6. First, the ballistic performances of each candidate materials are examined by doing the semi-infinite target simulation to estimate the depth of penetration (DOP) data. The materials included in this study are four (tungsten alloy, mild steel, SiC, MMC. The MMC materials are SiC/Al7075 (volume fraction around 45%). For a reference data, the impact simulation into mild-steel target only was also carried out. Finally, the main simulation is performed by varying the position of ceramic tile at three types of the thickness of ceramic tile. The residual velocity, residual mass and residual kinetic energy of the long-rod are obtained from the simulation. Based on these predicted values, the optimum system of the layered plate has been estimated.

scholarly journals Designing Shock Absorbing Composites by Impregnating Woven Fabrics with Shear Thickening Fluids

2021 ◽  
Vol 10 (2) ◽  
Author(s):  
Aaditya Saha ◽  
Fred Avett
Keyword(s):  
Impact Resistance ◽  
Shear Thickening ◽  
Force Sensor ◽  
Woven Fabrics ◽  
Polyurethane Foams ◽  
Nano Particle ◽  
Shock Absorption ◽  
Carrier Fluid ◽  
Shear Thickening Fluids ◽  
The Impact

Millions of sports and recreation-related injuries occur each year. Different shock-absorbing solutions, such as polyethylene and polyurethane foams, are used in helmets and protective equipment, but one area most sports-gear manufacturers have not explored is the usage of shear thickening fluids (STFs). An STF is a material that is soft under normal conditions but acts rigid when stressed or pressured. STF composites were fabricated and tested with the goal of exploring their viability for use in shock-absorption applications, especially for sports. The role of fabric- and particle-type, particle-to-carrier fluid ratios, nano-particle additives, and the thickness of the composite were studied, and were all hypothesized to have an effect on the impact-resistance of the fabricated STF-composites. Drop-tests were conducted by releasing a 1.1-lb. weight from an electromagnet onto the composites. An impact-force sensor was placed underneath. The weight and height of the drop were chosen to simulate the hardest recorded NFL hit. All hypothesized factors were found to affect impact resistance. The combination of nylon-fabric impregnated by an STF mix of propylene-glycol and silica-nanoparticles, with a cerium-oxide nano-particle additive, displayed better shock-absorption behavior than other fabricated composites. All of the STF-composites also outperformed tested commercial shock-absorption materials despite being thinner and more flexible. These results demonstrate the potential of using STF-impregnated textile fabrics for protective composites for sportswear, as well as for non-sport shock-absorption applications, like in military vests and helmets, and aerospace applications. Further research is necessary to work towards a final product which can be used.

scholarly journals Impact and Ricochet of a High Speed Projectile from a Plate

2021 ◽  
Vol 71 (6) ◽  
pp. 737-747
Author(s):  
Hussein Bassindowa ◽  
Bakhtier Farouk ◽  
Steven B. Segletes
Keyword(s):  
Titanium Alloy ◽  
High Speed ◽  
Computational Study ◽  
Incident Angle ◽  
Finite Thickness ◽  
Impact Angle ◽  
Projectile Velocity ◽  
Alloy Plate ◽  
Impact Angles ◽  
The Impact

A computational study of a projectile (either 2024 aluminum or TiAl6V4 titanium alloy) impacting a plate (either titanium alloy or aluminum) is presented in this paper. Projectile velocity (ranging from 250 m/s to 1500 m/s) with varying impact angles are considered. The presence of ricochet (if any) is identified over the ranges of the projectile velocity and impact angle considered. For the cases where ricochet is identified, the ricochet angle and velocity are predicted as functions of the incident angle and the incident velocity. The numerical results are compared with an analytical solution of the ricochet problem. The analytical solutions are from a model developed to predict the ballistic ricochet of a projectile (projectile) penetrator. The dynamics and the deformation of an aluminum (or a titanium alloy) projectile impacting on a finite thickness titanium alloy (or aluminum) plate are simulated. The current work is interesting in that it looks in the field of ballistics of different material combinations than are traditionally studied. The present simulations based on detailed material models for the aluminum and the titanium alloy and the impact physics modelling features in the LS-DYNA code provide interesting details regarding the projectile/plate deformations and post-impact projectile shape and geometry. The present results indicate that for no cases (for specified incoming velocities and impact angles considered) can an aluminum projectile penetrate a titanium alloy plate. The ricochet ‘mode predictions ‘obtained from the present simulations agree well with the ricochet ‘mode predictions’ given in an analytical model.

scholarly journals Integrated Periodic Timetabling and Vehicle Circulation Scheduling

2021 ◽  
Author(s):  
Rolf N. Van Lieshout
Keyword(s):  
Public Transport ◽  
Computational Study ◽  
Valid Inequalities ◽  
High Quality ◽  
Trade Off ◽  
The Public ◽  
Average Travel Time ◽  
Periodic Timetabling ◽  
The Cost ◽  
The Impact

Periodic timetabling is one of the most well-researched problems in the public transport optimization literature. However, the impact that timetabling has on the number of required vehicles, which directly translates to operator costs, is rarely considered. Therefore, in this paper, we consider the problem of jointly optimizing the timetable and the vehicle circulation schedule, which specifies the cyclic sequences of trips that vehicles perform. In order to obtain high-quality solutions to realistic instances, we improve an earlier proposed formulation by contraction techniques, three new valid inequalities, and symmetry-breaking constraints. Ultimately, this allows us to explore the trade-off between the number of vehicles and the attractiveness of the timetable from the passengers’ perspective. An extensive computational study demonstrates the effectiveness of the improved formulation. Moreover, using this approach, we are able to find timetables requiring substantially fewer vehicles at the cost of minimal increases of the average travel time of passengers.

Experimental Investigation of Volume Fraction in an Annulus Using Electrical Resistance Tomography

SPE Journal ◽  
2019 ◽  
Vol 24 (05) ◽  
pp. 1947-1956 ◽  
Author(s):  
Syed Raza Rehman ◽  
Alap Ali Zahid ◽  
Anwarul Hasan ◽  
Ibrahim Hassan ◽  
Mohammad A. Rahman ◽  
...  
Keyword(s):  
Multiphase Flow ◽  
Electrical Resistance ◽  
High Speed ◽  
Volume Fraction ◽  
Flow Behavior ◽  
Complex Flow ◽  
Flow Loop ◽  
Electrical Resistance Tomography ◽  
Horizontal Drilling ◽  
Hole Cleaning

Summary Horizontal drilling technology has shown to improve the production and cost–effectiveness of the well by generating multiple extraction points from a single vertical well. The efficiency of hole cleaning is reduced because of the solid–cuttings accumulation in the annulus in cases of extended–reach drilling. It is difficult to study the complex flow behavior in a drilling annulus using the existing visualization techniques. In this study, experiments were carried out in the multiphase flow–loop system consisting of a simulated drilling annulus using electrical resistance tomography (ERT) and a high–speed camera. Real–time tomographic images (quantitative visualization) of multiphase flow from ERT were compared to the actual photographs of the flow conditions in a drilling annulus. The quantitative analysis demonstrates that ERT has a wide potential application in studying the hole–cleaning issues in the drilling industry.

Two-dimensional (2D) fabrics and three-dimensional (3D) preforms for ballistic and stabbing protection: A review

2016 ◽  
Vol 87 (18) ◽  
pp. 2275-2304 ◽  
Author(s):  
Kadir Bilisik
Keyword(s):  
Impact Resistance ◽  
Three Dimensional ◽  
Shear Thickening ◽  
High Strength ◽  
Computational Techniques ◽  
Two Dimensional ◽  
Shear Thickening Fluids ◽  
Recent Developments ◽  
Ballistic Properties ◽  
The Impact

In this study, the impact resistance of two-dimensional (2D) fabrics and three-dimensional (3D) preforms is explained. These fabrics and preforms include 2D and 3D woven and knitted flat and circular fabrics. Various types of soft/layered structures as well as rigid composite are outlined with some design examples for ballistic and stab threats. The recent developments in nanotubes/nanofibers and shear-thickening fluids (STF) for ballistic fabrics are reviewed. The ballistic properties of single- and multi-layered fabrics are discussed. Their impact mechanism is explained for both soft vest and rigid armor applications. Analytical modeling and computational techniques for the estimation of ballistic properties are outlined. It is concluded that the ballistic/stab properties of fiber-reinforced soft and rigid composites can be enhanced by using high-strength fibers and tough matrices as well as specialized nanomaterials. Ballistic/stab resistance properties were also improved by the development of special fabric architectures. All these design factors are of primary importance for achieving flexible and lightweight ballistic structures with a high ballistic limit.

Composition – Property Relations in Shear Thickening Fluids

2014 ◽  
Vol 87 ◽  
pp. 91-97
Author(s):  
Łukasz Wierzbicki ◽  
Marcin Leonowicz
Keyword(s):  
High Strain ◽  
Volume Fraction ◽  
Solid Phase ◽  
Loss Modulus ◽  
Shear Thickening ◽  
Complex Viscosity ◽  
High Viscosity ◽  
Polypropylene Glycol ◽  
Shear Thickening Fluids ◽  
Composition Property

It was shown that fumed silica particles (FS), dispersed in polypropylene glycol (PPG), form shear thickening fluids (STF). PPGs with different molar mass were tested. The best combination of the properties (high viscosity, obtained at high shear rate) present the fluids composed of 7 nm FS and PPG 425. The highest volume fraction of FS, which was possible to disperse in PPG 425, was 25%. This fluid exhibited the highest viscosity. The highest magnitude of shear thickening effect was obtained, however, for 17.5 vol.% of the solid phase. Dynamic oscillatory shear experiments were conducted at either a constant amplitude or frequency. The constant strain amplitude tests showed, that for the frequency sweep, the systems showed viscous properties, except that of 25 vol.% of FS in PPG 425, which exhibited elastic properties in almost entire range of the frequency investigated. For the constant strain sweep, for low strains, the elastic modulus and loss modulus were hardly dependent on the strain, but for relatively high strain, this dependency was increasing. Also the complex viscosity was also growing for high strain values.

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