Micromechanics

About: Micromechanics is a research topic. Over the lifetime, 6000 publications have been published within this topic receiving 162635 citations.

Characterization of electrical and thermal properties of carbon nanotube/epoxy composites

Abstract: The electrical and thermal conductivity of pristine, oxidized, and fluorinated single-wall/multi-wall carbon nanotube (CNT) mixtures, dispersed in epoxy, were investigated as a function of CNT concentration. The effect of fabrication parameters, such as stirring rate and degree of epoxy pre-curing, on CNT dispersion was analyzed. The electrical conductivity increased by 10 and 6 orders of magnitude for pristine and oxidized CNT composites, respectively, relative to neat epoxy, while fluorinated CNT composites showed no increase in electrical conductivity. An increase of up to 5.5% was observed in thermal conductivity for pristine CNT composites while oxidized and fluorinated CNTs provide less enhancement in thermal conductivity. A micromechanics model, based on the composite cylinders method, was implemented to study the electrical and thermal conductivity of these composites. Effects in electrical and thermal conduction, such as electron hopping and thermal interface resistance, respectively, were incorporated into the model to accurately simulate the acquired experimental results.

Measurement of Epoxy Resin Tension, Compression, and Shear Stress–Strain Curves over a Wide Range of Strain Rates Using Small Test Specimens

Abstract: The next generation aircraft engines are designed to be lighter and stronger than engines currently in use by using carbon fiber composites. In order to certify these engines, ballistic impact tests and computational analyses must be completed, which will simulate a “blade out” event in a catastrophic engine failure In order to computationally simulate the engine failure, properties of the carbon fiber and resin matrix must be known. When conducting computer simulations using a micromechanics approach, experimental tensile, compressive, and shear data are needed for constitutive modeling of the resin matrix material. The material properties of an Epon E862 epoxy resin will be investigated because it is a commercial 176°C (350°F) cure resin currently being used in these aircraft engines. These properties will be measured using optical measurement techniques. The epoxy specimens will be tested in tension, compression and torsional loadings under various strain rates ranging from 10−5 to 10−1 s−1 and tempera...