An instrumented indentation method is developed for generating maps of time-dependent viscoelastic and time-independent plastic properties of polymeric materials. The method is based on a pyramidal indentation model consisting of two quadratic viscoelastic Kelvin-like elements and a quadratic plastic element in series. Closed-form solutions for indentation displacement under constant load and c...

Alginate microcapsules containing epoxy resin were developed through electrospraying method and embedded into epoxy matrix to produce a capsule-based self-healing composite system. These formaldehyde free alginate/epoxy microcapsules were characterized via light microscope, field emission scanning electron microscope, fourier transform infrared spectroscopy and thermogravimetric analysis. Resul...

Improved dimensional stability of composites is desired in applications where they are exposed to varying temperature conditions. The current study aims at analyzing the effect of vapor-grown carbon nanofibers (CNFs) on the thermal expansion behavior of epoxy matrix composites and hollow particlefilled composites (syntactic foams). CNFs have a lower coefficient of thermal expansion (CTE) than e...

fiber metal laminates (fmls) are new composite materials consisting of thin metal layers and high strength composite layers. arall (aramid aluminum laminate) is a family of the fml that consists of thin aluminum sheets along with kevlar/epoxy composite layers. this material has many advantages such as light weight, excellent corrosion, fatigue and impact resistance. since, arall is a new materi...

In this paper, mechanical buckling analysis of composite annular sector plates with bean shape cut out is studied. Composite material sector plate made of Glass-Epoxy and Graphite-Epoxy with eight layers with same thickness but different fiber angles for each layer. Mechanical loading to form of uniform pressure loading in radial, environmental and biaxial directions is assumed. The method used...

Microencapsulated dicyclopentadiene (DCPD) healing agent and Grubbs’ Ru catalyst are incorporated into an epoxy matrix to produce a polymer composite capable of self-healing. The fracture toughness and healing efficiency of this composite are measured using a tapered double-cantilever beam (TDCB) specimen. Both the virgin and healed fracture toughness depend strongly on the size and concentrati...

The propagation of electrical trees along interfaces in epoxy resin is described. The electrical trees grew in needle-plane samples without and with internal barriers up to the final breakdown. The barrier materials glass, mica and PTFE had been chosen because they have significantly different bond mechanisms to the epoxy resin as well as being common materials in various composite high voltage...

It is difficult to detect delamination of rotating composite components like helicopter and wind turbine blades while in-service with a wired system. In the present study, a wireless system using a tiny oscillation circuit for detecting delamination of carbon/epoxy composites is proposed. In this system, a tiny oscillation circuit is attached to the composite component. When delamination of the...

The influence of surface modifications on the mechanical properties of epoxy-hexagonal boron nitride nanoflake (BNNF) nanocomposites is investigated. Homogeneous distributions of boron nitride nanoflakes in a polymer matrix, preserving intrinsic material properties of boron nitride nanoflakes, is the key to successful composite applications. Here, a method is suggested to obtain noncovalently f...

The focus of this work is the evaluation of the physical compatibility between an epoxy resin used as a matrix and an oxidized, unsized carbon fiber, and between this same epoxy resin and glassy carbon. For this purpose, carbon fibers, glassy carbon and epoxy resin have been assigned Hansen solubility (cohesion) parameters (HSP) by analysis of their interactions with a set of well-defined liqui...