Micromechanics

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

Micromechanics modelling for the constitutive behavior of polycrystalline shape memory alloys. I: Derivation of general relations

Abstract: A MICROMECHANICS constitutive model has been proposed in this paper to describe the pseudoelastic and shape memory behavior of polycrystalline shape memory alloys under various temperatures The derivation of the model is based on the thermodynamics, micromechanics and microstructural physical mechanism analysis of the material during deformation and it is shown that the inelastic deformation of the material in the mechanical and/or thermal loading processes is associated with some temperature, stress state and loading history dependent yielding surfaces which microscopically correspond to the forward and reverse transformation (or reorientation) processes, respectively

3D Fibre Reinforced Polymer Composites

Abstract: Introduction: Background Introduction to 3D FRP composites Manufacture of 3D Fibre Preforms: Weaving Braiding Knitting Stitching Preform Consolidation Liquid moulding techniques Resin selection Tooling Component quality. Micromechanics Models for Mechanical Properties: Fundamentals in micromechanics Unit cell models for 2D woven composites Models for 3D woven composites Unit cell models for braided and knitted composites. 3D Woven Composites: Microstructural properties of 3D woven composites In-plane mechanical properties of 3D woven composites Interlaminar fracture properties of 3D woven composites 3D woven distance fabric composites. Braided Composite Materials: In-plane mechanical properties Fracture toughness and damage performance Fatigue performance Modelling of braided composites. Knitted Composite Materials: In-plane mechanical properties Interlaminar fracture toughness Impact performance Modelling of knitted composites. Stitched Composites: The Stitching process Mechanical properties of stitched composites Interlaminar properties of stitched composites Stitched composite joints. Z-Pinned Composites Fabrication of Z-pinned composites Mechanical properties of Z-pinned composites Delamination resistance and damage tolerance of Z-pinned composites Z-Pinned sandwich composites.

Effective Elastic Properties of Carbon Nanotube Reinforced Composites

Abstract: We seek to obtain continuum level elastic properties for carbon nanotubes and carbon nanotube reinforced composites through a variety of micromechanics techniques. Using the in-plane elastic properties of graphene sheets the effective properties of carbon nanotubes are calculated using a modified composite cylinders micromechanics technique to treat the hollow nanotube as a transversely isotropic solid cylinder. Effective properties found for single-walled carbon nanotubes in this fashion are found to be in good agreement with both experimentally and theoretically obtained results available in the literature. Having a solid fiber then allows for the calculation of an Eshelby tensor and hence, the use of additional more advanced micromechanics techniques to calculate carbon nanotube reinforced composite effective elastic properties. In what are termed two-step approaches, the generalized self-consistent and Mori-Tanaka micromechanics techniques are employed to obtain effective elastic properties of composites consisting of aligned single or multi-walled effective carbon nanotubes embedded in a polymer matrix of EPON 862 at various effective carbon nanotube volume fractions. These results are compared to a single step composite cylinders approach wherein an additional phase consisting of the polymer matrix is placed around the carbon nanotube prior to obtaining the effective carbon nanotube properties, thereby obtaining the effective composite properties in a single calculation. It is found that the two-step Mori-Tanaka results yield nearly identical results as the single step composites cylinders approach. Finally, it has been observed in the literature that electrostatic clumping of nanotubes into nanotube bundles complicates the adequate dispersion of the nanotubes within the polymer matrix. The quantification and modeling of this clustering in aligned nanotube composites is accomplished herein using Dirichlet tessellation in conjunction with an n-phase generalized self-consistent technique. It is observed that the effect of clustering is to reduce in magnitude only the transverse to fiber alignment properties of the transversely isotropic effective composite as compared to the randomly distributed aligned carbon nanotube composite’s effective elastic properties, and that this reduction in transverse elastic properties increases with increasing global volume fraction of effective carbon nanotubes. Results indicate that, while the clustering effect does contribute to some reduction in composite properties, other factors such as cluster misalignment and poor fiber-matrix bonding may play a significantly larger role. Nomenclature 11 E = the one-direction Young’s modulus 12 ν = the one-direction Poisson’s ratio 23 κ = the 2-3-plane bulk modulus 12 μ = the 1-2-plane shear modulus 23 μ = the 2-3 plane shear modulus A E = the axial Young’s modulus of a fiber

Simplified composite micromechanics equations for hygral, thermal and mechanical properties

Abstract: A unified set of composite micromechanics equations of simple form is summarized and described. This unified set can be used to predict unidirectional composite (ply) geometric, mechanical, thermal and hygral properties using constituent material (fiber/matrix) properties. This unified set also includes approximate equations for predicting (1) moisture absorption; (2) glass transition temperature of wet resins; and (3) hygrothermal degradation effects. Several numerical examples are worked-out to illustrate ease of use and versatility of these equations. These numerical examples also demonstrate the interrelationship of the various factors (geometric to environmental) and help provide insight into composite behavior at the micromechanistic level.

Composites Engineering Handbook

Abstract: Introduction - definitions, classifications and applications. Part 1 Constituents: fibres, fabrics and fillers matrix resins and fibre/matrix adhesion. Part 2 Mechanics: micromechanics mechanics of laminated structures mechanics of woven fabric composites fracture and damage mechanics in laminated composites. Part 3 Processing: processing for laminated structures press moulding processes filament winding the pultrusion process for continuous automated manufacture of engineered composite profiles processing of thermoplastic matrix composites processing of particle-reinforced metal matrix composites joining and repair of aircraft composite structures machining of composite materials. Part 4 Properties and performance: laminated polymer matrix composites random fibre composites selection guidelines for metal matrix composites ceramic matrix composites cement matrix composites. Part 5 Testing: mechanical property measurements nondestructive tests. Part 6 Engineering with composite materials: design methodology and practices materials selection, preliminary design and sizing for composite laminates design guidelines for laminated composites.