scholarly journals Thermal stability of the elastomeric anti-trauma pad

2017 ◽  
Vol 19 (2) ◽  
pp. 93-100
Author(s):  
Karolina Olszewska ◽  
Dorota Zielinska ◽  
Marcin H. Struszczyk ◽  
Łukasz Wierzbicki ◽  
Marcin K. Leonowicz
Keyword(s):  
Aging Process ◽  
Volume Fraction ◽  
Accelerated Aging ◽  
Shear Thickening ◽  
Chemical Degradation ◽  
Polypropylene Glycol ◽  
Shear Thickening Fluid ◽  
Vis Spectroscopy ◽  
Ballistic Properties ◽  
Thermographic Analysis

AbstractThe elastomeric anti-trauma pad (EA-TP) based on shear thickening fluid (STF) has been developed. Dynamic oscillatory shear experiment was conducted at constant strain amplitude of 5%. STF composed of 25% of volume fraction of 7 nm Fumed Silica, dispersed in polypropylene glycol with molar mass 400 gmol−1shows elastic properties in entire investigated range of the frequency. Ballistic tests of EA-TP with 7.62 mm × 39 mm PS bullets were performed according to the PN-V-87000:2011 standard. The studies revealed about 60% reduction of the average backface signature depth (BSD) for the EA-TP, when compared to the nowadays commonly used soft insert. The ATR-FTIR analysis confirmed slight impact of the elevated temperature and air (oxygen) on the chemical degradation of the EA-TP surface. The UV-VIS spectroscopy has allowed to notice colour deviation of the aged samples towards green and yellow, as well as lack of dye resistance to accelerated aging process. Thermographic analysis has shown no visible changes of the EA-TP surface and sub-surface during accelerated aging process. The aforementioned small changes on the surface of EA-TP did not affect the ballistic properties of composite armour. EA-TP insert maintains ballistic properties after accelerated aging process which was simulating the period of 6 years according to ASTM F1980 – 07:2002 standard.

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.

Rheological Fluids for Energy Absorbing Systems

2013 ◽  
Vol 440 ◽  
pp. 13-18 ◽  
Author(s):  
Marcin Leonowicz ◽  
Joanna Kozłowska ◽  
Łukasz Wierzbicki
Keyword(s):  
Magnetic Field ◽  
Carbonyl Iron ◽  
Volume Fraction ◽  
Loss Modulus ◽  
Shear Thickening ◽  
High Viscosity ◽  
Polypropylene Glycol ◽  
Magneto Rheological ◽  
Energy Absorbing ◽  
Protective Performance

Two types of non-Newtonian fluids, magneto rheological (MRF) and shear thickening (STF) fluids, respectively were chosen as candidates for energy dissipation study in smart body armour. A series of magneto rheological fluids was synthesized on a basis of synthetic oil and carbonyl iron. The shear modules for the MRF containing 75 wt% of carbonyl iron, obtained in a magnetic field of 230 kA/m were as follows: complex shear modulus G* - 1.2 MPa, storage modulus G-1.2 MPa and loss modulus G 0.35 MPa. The studies revealed also that the silica fumed, dispersed in polypropylene glycol or polyethylene oxide, demonstrates shear thickening properties. The best combination of the properties (high viscosity, obtained at high shear rate) represents the material composed of the silica fumed (SF) and PEO300. Change of the volume fraction of the SF and variation of the molecular weight of the oligomer enables tailoring of the STF properties. Ballistic tests revealed that the structures containing PE bags with MRF (in magnetic field) or STF can enhance the protective performance of body armours providing their flexibility.

The Ballistic Performance of Multi-Layer Kevlar Fabrics Impregnated with Shear Thickening Fluids

2015 ◽  
Vol 782 ◽  
pp. 153-157 ◽  
Author(s):  
Yan Wang ◽  
Shu Kui Li ◽  
Xin Ya Feng
Keyword(s):  
Particle Size ◽  
Coupling Effect ◽  
Shear Thickening ◽  
Silica Particles ◽  
Ballistic Performance ◽  
Shear Thickening Fluid ◽  
Aramid Fabric ◽  
Shear Thickening Fluids ◽  
Ballistic Properties ◽  
Ballistic Test

This study investigates the ballistic penetration performance of aramid fabric impregnated with shear thickening fluid. The ballistic test was conducted at impact velocity of 445 m/s, and three types of shear thickening fluids prepared with silica particles of different sizes (200nm, 340nm and 480nm) are involved. The results demonstrate an enhancement in ballistic properties of fabric due to the impregnation of shear thickening fluids. The fabrics with smaller particle size show better ballistic performance. Microscopic observation of aramid fabric reveals that shear thickening fluids with smaller silica particles have a better adhesion on and between yarns, enhancinging the coupling effect between yarns. The corresponding mechanism was discussed in the paper.

scholarly journals Static puncture resistance characteristics with various indenter nose shape geometry perforation of shear thickening fluid impregnated polypropylene fabric for soft armour application

2022 ◽  
Vol 30 ◽  
pp. 096739112110633
Author(s):  
Deepak SampathKumar ◽  
Thirumalaikumarasamy Duraisamy ◽  
Thirumal Pattabi ◽  
AshokKumar Mohankumar
Keyword(s):  
Volume Fraction ◽  
Shear Thickening ◽  
Shear Thickening Fluid ◽  
Puncture Resistance ◽  
Dry Process ◽  
Highly Sensitive ◽  
Study Results ◽  
Target Sample ◽  
Nose Shape ◽  
Silica Microparticles

At present, puncture resistance and rheological performance of shear thickening fluid (STF) is an essential design requirement for a soft armour material (target sample). The target sample is prepared with a dip and dry process of STF impregnated woven polypropylene (PP) fabric. These samples were tested and compared with neat PP fabric. The penetration depth of target samples is highly sensitive to the coefficient of friction between the indenter’s nose shape geometry and the target sample. The STF is prepared by mechanical dispersion of synthesized microsphere silica microparticles at a volume fraction of 57% in polyethylene glycol (400 g/mol). The rheological response indicates that the prepared concentration of silica microparticles in the STF suspension is observed to have a better shear thickening effect. The viscosity of suspension is highly sensitive to silica aspect ratio, volume fraction and particle size distribution in this work. Tensile tests along with puncture resistance with different indenter nose shapes geometry (hemispherical, elliptical, flat and conical) have been performed in the present study. Results indicate that the energy absorption is more with the hemispherical indenter and less with that of the conical indenter, which is attributed to the minimum surface area of contact as compared to all other indenters. A total of 16 number of fabricated target samples with various coating thicknesses of STF impregnated fabrics achieved the desired tensile strength, modulus and puncture resistance.

Development of Flexible Extremities Protection utilizing Shear Thickening Fluid/Fabric Composites

2012 ◽  
Author(s):  
Mahesh Hosur ◽  
Norman Wagner ◽  
C. T. Sun ◽  
Vijaya Rangari ◽  
Jack Gillespie ◽  
...  
Keyword(s):  
Shear Thickening ◽  
Shear Thickening Fluid ◽  
Fabric Composites

Dynamic compressive response of 3D GFRP composites with shear thickening fluid (STF) matrix as cushioning materials

2021 ◽  
pp. 002199832098424
Author(s):  
Mohsen Jeddi ◽  
Mojtaba Yazdani
Keyword(s):  
Shear Thickening ◽  
Low Velocity Impact ◽  
Gfrp Composites ◽  
High Concentration ◽  
Low Velocity ◽  
Shear Thickening Fluid ◽  
Compressive Response ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced ◽  
Shear Thickening Fluids

Whereas most previous studies have focused on improving the penetration resistance of Shear Thickening Fluids (STFs) treated composites, in this study, the dynamic compressive response of single and multi-ply 3 D E-Glass Fiber Reinforced Polymer (GFRP) composites with the STF matrix was investigated by using a drop-weight low-velocity impact test. The experimental results revealed the STF improved the compressive and cushioning performance of the composites such that with increasing its concentration, further improvement was observed. The five-ply composite containing the STF of 30 wt% silica nanoparticles and 1 wt% carbon nanotubes (CNTs) reduced the applied peak force by 56% and 26% compared to a steel plate and five-ply neat samples, respectively. A series of repeated impacts was performed, and it was found that the performance of high-concentration composites is further decreased under this type of loading.

Impact resistance of shear thickening fluid/Kevlar composite treated with shear-stiffening gel

2018 ◽  
Vol 106 ◽  
pp. 82-90 ◽  
Author(s):  
Qianyun He ◽  
Saisai Cao ◽  
Yunpeng Wang ◽  
Shouhu Xuan ◽  
Pengfei Wang ◽  
...  
Keyword(s):  
Impact Resistance ◽  
Shear Thickening ◽  
Shear Thickening Fluid
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