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The compression properties of three-dimensional angle-interlock woven E-glass fabric/vinyl ester composite material along thickness direction under quasi-static (0.001 s−1) and high strain rates (800, 1600, and 2700 s−1) were investigated with finite element method and compared with those in experimental. The finite element method model was based on the three-dimensional woven composite microstructure. It was found that the compressive properties are sensitive to strain rate both in finite element method and experimental. The finite element method results showed good agreements with that of experimental in stress–strain curves and fracture morphologies. The obvious strain rate sensitivity of the compression properties and failure modes of three-dimensional angle interlock composites was both verified with the finite element method model and results in experimental. The compressive stiffness and maximum compressive stress increased with the strain rate while the failure strain showed an opposite trend. The failure mode is mainly in shear failure. The compressive failure mechanisms have been analyzed from the different components of the three-dimensional woven composites. [ABSTRACT FROM AUTHOR]

The compressive behaviour of epoxy based syntactic foams filled by ceramic microballoons is experimentally investigated in this study. Nine different types of syntactic foams are fabricated with three different microballoon sizes and three different microballoon fractions. All of the syntactic foam specimens are tested at various strain rates from quasi-static to high strain rates. Analysis of the results is carried out on the effect of the volume fraction, microballoon size and strain rate on the compressive behaviour of syntactic foams. Also, scanning electron microscopy is used to understand the fracture mechanisms of tested specimens. The results show that as the microballoon volume fraction increases the compressive strength, compressive modulus, failure strain and plateau stress decreases for all types of syntactic foams at all strain rates. Although, this decrease is slight for 20% and 40% volume fraction, it is considerable for 60% microballoon volume fraction syntactic foam. The results indicate that reducing the microballoon size or increasing the strain rate of testing would enhance the compressive strength. [ABSTRACT FROM AUTHOR]

In this study, uniaxial compressive properties of pure magnesium and Mg/(Y 2O3 + Cu) hybrid nanocomposites are investigated. Addition of hybrid reinforcements (ceramic + metal) at nano-length scale led to grain-size refinement and the amount of porosity remained below 1%. The presence of hybrid reinforcements led to a significant increase in 0.2% compressive yield strength (CYS) and ultimate compressive strength (UCS) while the failure strain was compromised. Best improvements in 0.2% CYS, UCS, and hardness were realized when the amount of copper was increased to one volume percent for fixed 0.7% Y2O3 nanoparticulates. Comparatively low ductility of magnesium hybrid nanocomposites under compressive loading was attributed to the absence of twinning unlike pure magnesium. The variation in the mechanical properties in this study is correlated with the microstructural features and texture effects. [ABSTRACT FROM AUTHOR]

In the present study, new light weight nanocomposites (AZ31-1.5Al2O3-Ca) based on magnesium alloy AZ31B are developed using disintegrated melt deposition technique. Microstructural characterization studies revealed equiaxed grain structure, minimal porosity, and good matrix-reinforcement interfacial integrity. The results also showed that addition of both nano-Al2O3 and Ca led to a simultaneous improvement in 0.2% yield compressive strength (0.2% YCS), ultimate compressive strength (UCS), and work of fracture (WoF) of the AZ31B magnesium alloy while failure strain was slightly compromised. Moreover, excellent oxidation resistance of this composite was realized when compared to AZ31B up to 500°C. The results suggest that this composite formulation can be used in diverse engineering applications requiring light weight structural materials. [ABSTRACT FROM AUTHOR]

Solidification processing followed by hot coextrusion was used to fabricate a bimetal magnesium/aluminum macrocomposite containing millimeter- scale Al core reinforcement. Microstructural characterization revealed limited interfacial interdiffusion of both metals into each other. Compressive testing revealed that the presence of Al core does not affect 0.2%YS, marginally decreases ultimate compressive strength (UCS), and significantly increases failure strain (115%) and work of fracture (55%) of Mg. The effect of the presence of mm-scale Al core on the compressive properties of the bimetal macrocomposite is investigated in this article. [ABSTRACT FROM AUTHOR]

Methods for dynamic characterization of composite materials were extended and applied to the study of strain rate effects under transverse compression as well as shear. Falling weight impact and Split Hopkinson Pressure Bar systems were developed for dynamic characterization of composite materials in compression and shear at strain rates up to 1800 sO. Strain rates below 10 s5l were generated using a servohydraulic testing machine. Strain rates between 10 sol and 300 sol were generated using the drop tower apparatus. Strain rates above 500 s-l were generated using the Split Hopkinson Pressure Bar.Seventy-two and forty-eight ply unidirectional carbon/epoxy laminates (IM6G/3501-6) loaded in the transverse direction were characterized. Off-axis (15°, 300, 450 and 600) compression tests of the same unidirectional material were also conducted to obtain the in-plane shear stress-strain behavior. Strain rates over a wide range, from 10-4 s-1 (quasi-static) up to 1800 s-1, were recorded. The 90-degree properties, which are governed by the matrix,show an increase in modulus and strength over the static values but no significant change in ultimate strain. The stress-strain curve stiffens as the strain rate increases. This stiffening behavior is very significant in the nonlinear region for strain rates between 10-4 s-I and 1 s51. For strain rates above 1 s-1, the stress-strain behavior continues this stiffening trend until it is almost linear at a strain rate of 1800 s-1. The shear stress-strain behavior, which is also matrix-dominated, shows high nonlinearity with a plateau region at a stress level that increases significantly as the strain rate increases. [ABSTRACT FROM PUBLISHER]