Application de la technologie Shear Thickening Fluid pour les gilets pare-balles :: TPE Shear Thickening Fluid. Le kevlar est donc le matériau utilisé aujourd’hui pour les gilets par balles. Avant cette invention, l'industrie de l'armement cherchait à découvrir des fibres de plus en plus résistantes, sans résultat apparent puisque le kevlar reste le matériau le plus utilisé. Néanmoins, depuis 1994, faute de nouvelles technologies alliant l’efficacité à la légèreté et à la flexibilité, les gilets pare-balles ne se développeront pas. Il faut attendre 2001 pour que l’US army adopte et développe une nouvelle technologie qu’ils ont appelée Shear Thickening Fluid. Les deux grands inventeurs de cette nouvelle technologie sont : Norman J. Il vient de l'université du Delaware ( le Delaware est un Etat des Etats-Unis) Et Eric D.
On a vu dans la partie "le phénomène en détail" comment cette technologie fonctionnait. -l'histoire de cette nouvelle technologie (pourquoi avoir effectué des recherches dessus?) -sa commercialisation -ses avantages et inconvénients I-l'histoire de cette nouvelle technologie. Shear‐Thickening (“Dilatancy”) in Suspensions of Nonaggregating Solid Particles Dispersed in Newtonian Liquids | Browse - Journal of Rheology.
Abstract The literature on this subject stands currently at over 100 articles; this review seeks to present an overall picture of the subject, using the results of these articles. Concentrated suspensions of nonaggregating solid particles, if measured in the appropriate shear rate range, will always show (reversible) shear thickening. The actual nature of the shear thickening will depend on the parameters of the suspended phase: phase volume, particle size (distribution), particle shape, as well as those of the suspending phase (viscosity and the details of the deformation, i.e., shear or extensional flow, steady or transient, time and rate of deformation). The explanations offered for the phenomenon that are supported by independent physical measurements postulate that the increase in viscosity is due to the transition from a two‐dimensional layered arrangement of particles to a random three‐dimensional form.
Dilatant materials. “A dilatant material is one in which viscosity increases with the rate of shear.” (wikipedia) In other words, a dilatant material will become “thicker” or “harder” when it is hit. This is counter-intuitive… imagine a liquid that becomes solid when it is hit, then quickly returns to a liquid. A simple example of a dilatant material is called “oobleck“. Oobleck is a mixture of cornstarch and water. Click here to learn how to make oobleck at home. There is currently research going on that uses dilatant materials for flexible body armor.
Patent US20030077299 - Dilatant composition - Google Patents. [0060] Each of o/w emulsions (1) to (8) was prepared by preemulsifying a batch of the corresponding formulation shown in Table 1 and then subjecting the preemulsion to emulsification three times under 9×107 s−1 (2,800 kg/cm2) in a high-pressure emulsifying machine “DeBEE 2000” (trade name; manufactured by B.E.E. International Corporation). [0061] On the other hand, 2% aqueous solutions of the components (B) shown in Table 2 were prepared, respectively. [0062] Each composition was produced by mixing component (A) (5 parts by weight) in Table 1, the 2% aqueous solution of the corresponding component (B) (2 parts by weight) in Table 2, and purified water (3 parts by weight). Its dilatancy factor was measured by a method describe below. The results are also shown in Table 2. [0064] Measured by an oscillation viscometer (“CJV-5000”, trade name; manufactured by A & D Company) after left over standstill at 25° C. for 3 days. [0073] Each essence was obtained by the following procedure.
Journal of Non-Newtonian Fluid Mechanics - Shear-thickening and structure formation in polymer solutions. The phenomenon of shear-thickening has been investigated for solutions of several high molecular weight crystallizable polymers using capillary rheometry. The systems studied: polyethylene/xylene, polypropylene/tetralin, and poly(ethylene oxide)/ethanol have previously been investigated for their flow induced crystallization behavior. A shear-thickening pattern occurs in the relative viscosity vs. shear rate flow curves for the first two systems which, for the former of the two, also shows a strong molecular weight dependence. For the range of conditions studied, the poly(ethylene oxide)/ethanol system did not show shear-thickening, exhibiting instead a shear thinning pattern for the lower molecular weight sample studied and a constant viscosity high shear plateau for the higher MW system.
Journal of Non-Newtonian Fluid Mechanics - Normal stresses in extremely shear thickening polymer dispersions. Abstract Measurements of the first and second normal stress differences of an extremely shear thickening polymer dispersion have been performed at imposed shear stress both by means of a Rheometrics RDS and a home-made Normal Force Cell using cone-plate geometry. The sample is a 58.7 vol.% dispersion of styrene/ethyl acrylate copolymer particles with 280 nm average diameter in glycol. The spheres are electrostatically stabilized by negative charges due to carboxylic groups. In the regime of strong shear thickening a negative first normal stresses difference N1 is found, the absolute value of which is equal to the absolute value of the shear stress τ: N1 = -|τ|.
The experimentally observed relation of the apparent shear stress τa and apparent first normal stress difference N1a in plate-plate geometry, N1a= -|τa|, can be explained by assuming that only the sample part near the rim is shear thickening whereas the inner part remains in the low viscosity regime. Keywords. Richard Palmer --- D3O Energy Absorber -- articles & 2 US Patent Applications. DEFLEXION™ – Dow Corning’s high performance impact protective textile - Dow Corning. FAQs - D3O Lab. Good Sports | In-depth. 28 November 2005 A new generation of sports gear protects players from knocks and blows with an impact-absorbing elastomeric material. Stuart Nathan reports. When Jerzy Dudek, Poland’s goalkeeper, runs out on to the pitch for next year’s World Cup campaign, his gloves will have a distinctive orange strip running across the knuckles.
But this isn’t just another styling point for the image-driven sportswear industry. Known as d3o, the orange material has properties that could change the way protective materials are constructed. Based on a complex elastomeric compound discovered and developed at the University of Hertfordshire, d3o is a shear-thickening material. d3o Labs has incorporated it into a soft foam matrix, and Richard Palmer, d3o Labs’ chief executive, has devised a striking party piece to demonstrate its properties: donning a long-sleeved T-shirt with d3o panels sewn into the sleeves, he slams his elbow into the tabletop as hard as he can.
‘The colour’s our trademark,’ said Sudul.