Analysis of syntactic foam – GFRP sandwich composites for flexural loads
The use of glass microballoon (GMB) — epoxy syntactic foams as a sandwich core material is studied. The skins and foam core are fabricated and joined instantaneously unlike the procedures followed in the previous studies. Each successive layer of the sandwich is fabricated when the previous layer is in a semi-gelled state. These sandwich samples are characterized for their properties under flexural loading. The failure modes and mechanical properties are carefully investigated. The change in fabrication technique results in a significant increase in the load bearing pattern of the sandwich. In earlier studies, debonding was found to occur prematurely since the bonding between the skins and core is the weakest plane. Using the current technique, core cracking occurs first, followed by skin fiber breaking and debonding happens at the end. This ensures that the load carrying phase of the structure is extended considerably. The sandwich is also analytically studied using Reddy’s higher order shear deformation theory. A higher order theory is selected as the sandwich can no longer be considered as a thin beam and thus shear effects also need to be considered in addition to bending effects.
Syntactic foam core metal matrix sandwich composite: Compressive properties and strain rate effects
Abstract The present work is the first attempt to study metal matrix syntactic foam core sandwich composites. The sandwich is studied for microstructure and compressive properties at quasi-static and high strain rates. Under quasi-static compressive conditions, specimens were tested in the flatwise and edgewise orientations. The compressive strength, yield strength and plateau stress were higher in the flatwise orientation. Furthermore, both orientations for the sandwich composites showed a higher specific compressive strength and specific yield strength than the foam core alone. Failure initiated in the particles in the flatwise orientation, but in the carbon fabrics in the edgewise orientation. The results show that the fabric had a reinforcing effect under quasi-static conditions. The high strain rate (HSR) characterization was conducted in the strain rate range 525–845 s −1 using a split-Hopkinson pressure bar set-up equipped with a high speed image acquisition system. Within this strain rate range, the compressive strength of the sandwich is similar to that of the syntactic foam core alone. Upon review, the syntactic foam core metal matrix sandwich outperforms most of the syntactic foams in terms of energy absorption and compressive strength at comparable density levels.
Chemical-Looping Combustion of Biomass in a 10 kWth Reactor with Iron Oxide As an Oxygen Carrier
Chemical-looping combustion of biomass was carried out in a 10 kWth reactor with iron oxide as an oxygen carrier. A total 30 h of test was achieved with the same batch of iron oxide oxygen carrier. The effect of the fuel reactor temperature on gas composition of the fuel reactor and the air reactor, the proportion of biomass carbon reacting in the fuel reactor, and the conversion of biomass carbon to CO2 in the fuel reactor was experimentally investigated. The results showed that the CO production from biomass gasification with CO2 was more temperature dependent than the CO oxidation with iron oxide in the fuel reactor, and an increase in the fuel reactor temperature produced a higher increase for the CO production from biomass gasification than for the oxidation of CO by iron oxide. Although the conversion of biomass carbon to CO2 in the fuel reactor decreased with the increase of the fuel reactor temperature, there was a substantial increase in the proportion of biomass carbon reacting in the fuel react...