Shear Modulus

This paper reviews the processing, properties, and structure of carbon fibers. Carbon fibers are derived from several precursors, with polyacrylonitrile being the predominant precursor used today. Carbon fibers have high strength (3–7 GPa), high modulus (200–500 GPa), compressive strength (1–3 GPa), shear modulus (10–15 GPa), and low density (1.75–2.00 g/cm3). Carbon fibers made from pitch can have modulus, thermal, and electrical conductivities as high as 900 GPa, 1,000 W/mK, and 106 S/m, respectively. These fibers have become a dominant material in the aerospace industry and their use in the automotive and other industries is growing as their cost continues to come down.

Mechanical and surface properties of paint films treated with organic solvents and water have been investigated using a range of thermomechanical and dielectric techniques together with Fourier transform infrared spectroscopy and scanning electron microscopy. Changes in the nature of the surface after treatment were observed. The effect of water, propan-2-ol and propanone (acetone) immersion for 24 hours, and swabbing for a few minutes, on naturally aged 12 years old samples of lead white/linseed oil and burnt sienna/linseed oil could be measured directly in terms of change in the shear modulus of the paint films together with the accompanying change in the ratio of viscous to elastic components present in each system. Generally, the solvent-treated films became harder and showed reduced viscous components, whereas the water-treated samples became softer. There was a change in the dielectric properties of the leached films which pointed to the polar nature of the leachings. FTIR diffuse reflectance spectra supported this conclusion. Mittels einer Reihe von thermomechanischen und dielektrischen Verfahren sowie FT-IR-Spektroskopie und Scanning-Elektronenmikroskopie wurden die mechanischen und OberflÄcheneigenschaften von mit organischen Lösungsmitteln und Wasser behandelten Anstrichfilmen untersucht. Nach der Behandlung konnte eine VerÄnderung der OberflÄchenbeschaffenheit beobachtet werden. Der Effekt von 24-stündigem Eintauchen in bzw. paar minütigem Abtupfen mit Wasser, Propan-2-ol und Propanon (Azeton) von natürlich gealterten, 12 Jahre alten Proben von Bleiwei\/Leinöl und gebrannter Sienaerde/Leinöl konnte als Funktion des Schubmodules des Anstrichfilmes gemessen werden, begleitet von einem übergang von viskosen zu elastischen Komponenten in jedem System. Im allgemeinen wurden die lösungsmittelbehandelten Proben hÄrter und wiesen weniger viskose Bestandteile auf, wÄhrend die wasserbehandelten Proben weicher wurden. Es trat auch eine Änderung der dielektrischen Eigenschaften der ausgelaugten Filme auf, was auf den polaren Charakter des Auslaugungsvorganges hinweist. FT-IR Remissionsspektren bekrÄftigten diese Schlu\folgerung.

A micromechanics framework for the development of continuum-level constitutive models for the large-strain deformation of porous hyperelastic materials is presented. A kinematically admissible deformation field is assumed which enables the derivation of a strain energy density function for the porous material. The strain energy density function depends on the properties of the incompressible hyperelastic matrix material, the initial level of porosity, and the macroscopic deformation. Differentiation of the strain energy density function, with respect to deformation, provides an expression for the stress–strain behavior of the porous hyperelastic material. Example calculations are carried out for porous hyperelastic materials with a Neo–Hookean matrix. The constitutive model is used to predict the stress–strain behavior of the pore-containing matrix as a function of initial porosity and macroscopic loading conditions. Predictions of the dependence of the small-strain elastic response on porosity are compared to various estimates of effective elastic moduli for porous materials found in the literature. Constitutive model predictions of the small to large-strain deformation behavior compare well with results from numerical three-dimensional micromechanical multi-void cell models.

This paper reviews the processing, properties, and structure of carbon fibers. Carbon fibers are derived from several precursors, with polyacrylonitrile being the predominant precursor used today. Carbon fibers have high strength (3–7 GPa), high modulus (200–500 GPa), compressive strength (1–3 GPa), shear modulus (10–15 GPa), and low density (1.75–2.00 g/cm3). Carbon fibers made from pitch can have modulus, thermal, and

ABSTRACT This study investigates the effect of cement additive on some properties of asphalt binder using Superpave testing methods. Six cement-to-asphalt (C/A) ratios were considered in the study: 0.05, 0.10, 0.15, 0.20, 0.25 and 0.30 by volume of asphalt binder. The experimental tests that were conducted in the study included the Superpave rotational viscosity (RV) test and the dynamic shear rheometer (DSR) test. The RV test was conducted at the Superpave-specified high temperature of 135°C that represents the average mixing and laydown temperature, and at seven different rotational speeds of 5, 10, 20, 30, 50, 60, and 100rpm. On the other hand, the DSR test was conducted at four test temperatures of 58, 64, 70, and 76°C; one lower and two higher than the Superpave high performance grade (PG) temperature of the asphalt binder used in the study (PG 64). The loading frequency used in the DSR test was 10rad/s (1.59Hz) as specified by the Superpave system. Results of the study showed that the addition of Portland cement to asphalt binders increased the rotational viscosity (RV) of asphalt binders at 135°C and different rotational speeds. The C/A ratio of 0.15 was found to be the optimum ratio that achieved a balanced increase in the rotational viscosity and the value of the DSR G*/sinδ rutting parameter of asphalt binders. The C/A ratio had insignificant effects on the Newtonian behavior, the phase angle (δ), and the elastic behavior of asphalt binders. The increase in C/A ratio increased the stiffness of asphalt binders represented by the complex shear modulus (G*) value. The increase in the C/A ratio improved the rutting parameter, G*/sinδ value, at all temperatures. The increase in C/A ratio improved the Superpave high PG temperature (the high temperature at which the asphalt binder passed the Superpave criteria for G*/sinδ value). It was also shown that the best function that described the relationship between each of RV, G*, and G*/sinδ and the C/A ratio was the exponential function with high coefficient of determination (R2).