Light-Gas Gun Technology: A Historical Perspective

Swift, H. F.

doi:10.1007/3-540-27168-6_1

Cited by 18 publications

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“…Los proyectiles cilíndricos fueron descartados y se optó por usar proyectiles esféricos, empleando esferas de acero de 5.5 mm de diámetro. Se colocaron los proyectiles dentro de un dispositivo plástico denominado sabot en cada uno de los disparos para aumentar la capacidad de empuje de los gases y para que el impulso fuese lo más uniforme posible (Swift (2003)). El conjunto formado por el proyectil y el sabot una vez montado se ve en la figura 6.5.…”

Section: Descripción Del Cañón De Gas Y Elección Del Proyectilunclassified

Resistencia a impacto de morteros de cemento reforzados con fibra de vidrio (GRC)

Enfedaque¹

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The origin and use of cementitious materials dates from the civilization's origin. Egyptians were the first people that used hydraulic materials as gypsium; Romans and Greeks used volcanic ashes mixed with lime that produced a much better material than gypsium. However, Romans were the first to use cementitious mixes in common buildings.As is well known cementitious mixes are brittle and have a high compressive strength.To get a material with better mechanical properties reinforced concrete was developed, it is a compound of steel bars inside a concrete bulk. However, corrosion in steel bars appear due the chemical attack from the environment, and to avoid this phenomenon steels bars should have a few centimeters of concrete covering them. By doing so, elements of great mechanical properties are obtained but these elements are also very heavy. To solve this problem glass fiber reinforced cement (GRC) was developed based in the previous works done with glass fibers and polymeric matrices. GRC has the great compressive strength of cement mortars and the tensile strength of the glass fibers. GRC's superior mechanical properties are reduced with time. GRC becomes brittle, losses all ductility and its behavior can be considered as lineal and elastic up to failure. Aged GRC has the same behavior as cement mortar without any reinforcement. In order to reduce or avoid this harmful process, some chemical products have been added to the cement paste during GRC's manufacturing.In this work, a wide experimental programme has been carried out to evaluate the influence of the 6 chemical products added in GRC's mechanical properties. Pure tensile tests and 4 point bending tests have been done both in young GRC and in aged GRC (aged artificially IX Abstract by immersion in hot water tanks). GRC samples were aged up to a natural ageing process of 30 years.A wide and thoroughly study has been done in GRC fracture surfaces of tensile tested samples using an Scanning Electronic Microscope (SEM) searching the causes of the fragilization of GRC with time.GRC dynamic behavior and properties have been widely studied by doing medium and high strain rate tests. Medium strain rate tests were carried out in a drop machine on GRC plates. GRC's ballistic behavior was studied shooting steel spheres into GRC samples.Numerical simulations of the different tests were performed to analyze which GRC's mechanical properties have influence in the behavior of the material during the tests. GRC ageing was simulated by changing the characteristics of the fiber-matrix interface.Dynamic simulations were carried out in Autodyn v6 in order to check which GRC's properties had influence in GRC's dynamic behavior. X Capítulo 1Estado del arte 1.1. Descripción y fabricación del GRC El GRC es un material compuesto que está formado por una matriz de mortero de cemento y fibras cortas de vidrio. Fue ideado alrededor de 1950 como consecuencia del éxito de los materiales compuestos de matriz polimérica reforzados con fibras de vidrio. Se intentaron sustituir las arma...

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Section: Descripción Del Cañón De Gas Y Elección Del Proyectilunclassified