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Aswani Kumar Bandaru - One of the best experts on this subject based on the ideXlab platform.
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high strain rate compression testing of intra ply and inter ply hybrid thermoplastic composites reinforced with kevlar basalt fibers
Polymer Testing, 2020Co-Authors: Aswani Kumar Bandaru, Hemant Chouhan, Naresh BhatnagarAbstract:Abstract In this study, the influence of hybridization on the compression response of thermoplastic matrix-based composites under high strain rate loading was investigated. The intra-ply and inter-ply hybrid composites were manufactured with Kevlar/Basalt yarns as the reinforcements with Polypropylene as a matrix. Cylindrical composite specimens were laser cut from the flat compression moulded laminates. The composite specimens were loaded under high strain rate using split-Hopkinson pressure bar setup at strain rates ranging from 2815/s to 5481/s. The study revealed differences in the rate-dependent growth of Peak Stress, Peak strain and toughness with the strain rate. Intra-ply hybrid composites with alternate weaving of Kevlar and basalt yarns exhibited highest Peak Stress as compared to the Inter-ply hybrid composites (alternate layers of Kevlar and basalt fabrics) and another intra-ply composite containing Kevlar in the warp and basalt in the weft direction. Whereas in inter-ply hybrid composite, with Kevlar as the loading face attained higher Stress, while composite with Basalt as the loading face attained higher strain. SEM micrographs revealed that Kevlar on the loading face can bear the impact with lesser delamination as compared to the Basalt on the loading face. Damage studies revealed that Kevlar fiber surface loading results in higher Stress as compared to basalt (brittle) surface loading with lower overall damage.
D G Morris - One of the best experts on this subject based on the ideXlab platform.
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possibilities for high temperature strengthening in iron aluminides
Intermetallics, 1998Co-Authors: D G MorrisAbstract:Abstract Iron aluminides based on Fe 3 Al and on FeAl offer considerable possibilities for development as intermediate temperature materials operating in aggressive chemical environments. Two major property limitations restrict their application: low toughness, related to their environmental sensitivity, and poor high temperature creep resistance. Considerable attention has been given to the intermediate Stress but, while many of its characteristics are well documented, there remains considerable uncertainty about the controlling mechanisms. Plastic deformation at temperatures above the Stress Peak can be analysed in terms of thermally-activated, creep-like flow, with a steady evolution during deformation of many of the controlling parameters. Two avenues can be explored for improving high temperature behaviour: modify the diffusive flow behaviour and restrict dislocation motion at dispersed particles. There is considerable evidence that control of matrix composition can lead to large changes in diffusion parameters and the motion of dislocations. Dislocation pinning at particles depends on the availability of suitable particle phases, and examples of precipitated carbides, dispersed oxides, and decomposed intermetallic mixtures will be considered.
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dislocation processes leading to the Stress anomaly in b2 type fe 40 al single crystals
Intermetallics, 1997Co-Authors: D G Morris, M A MorrisAbstract:Abstract The anomalous Stress Peak has been examined in Fe-40%Al single crystals compressed along a direction near [001]. A sharp Stress Peak is observed at 525 °C with anomalous strengthening found only about 25 °C on each side of the sharp Peak. Deformation by 〈 111 〉 superdislocations at low temperatures is made more difficult near the Stress Peak as the dislocations react to produce short, essentially immobile 〈 100 〉 segments and as edge superdislocations decompose to 〈 100 〉 and 〈 110 〉 dislocations, poorly mobile at such temperatures. There is no evidence of superdislocation pinning by extensive cross-slip, by climb, or by interaction with vacancy loops. At temperatures immediately above the Stress Peak 〈 110 〉 and 〈 100 〉 dislocations move, while at higher temperatures 〈 100 〉 dislocations alone ensure deformation. The flow Stress falls because of the thermal activation of glide and because of the limited possibilities for dislocation pinning through intersections and reactions as deformation occurs by 〈 100 〉 dislocations alone. Many processes have been observed in the temperature range encompassing the Stress Peak and deducing the critical mechanisms is difficult. The role of the orientation of the applied Stress in determining the relative rate of dislocation interactions and glide is emphasized.
Naresh Bhatnagar - One of the best experts on this subject based on the ideXlab platform.
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high strain rate compression testing of intra ply and inter ply hybrid thermoplastic composites reinforced with kevlar basalt fibers
Polymer Testing, 2020Co-Authors: Aswani Kumar Bandaru, Hemant Chouhan, Naresh BhatnagarAbstract:Abstract In this study, the influence of hybridization on the compression response of thermoplastic matrix-based composites under high strain rate loading was investigated. The intra-ply and inter-ply hybrid composites were manufactured with Kevlar/Basalt yarns as the reinforcements with Polypropylene as a matrix. Cylindrical composite specimens were laser cut from the flat compression moulded laminates. The composite specimens were loaded under high strain rate using split-Hopkinson pressure bar setup at strain rates ranging from 2815/s to 5481/s. The study revealed differences in the rate-dependent growth of Peak Stress, Peak strain and toughness with the strain rate. Intra-ply hybrid composites with alternate weaving of Kevlar and basalt yarns exhibited highest Peak Stress as compared to the Inter-ply hybrid composites (alternate layers of Kevlar and basalt fabrics) and another intra-ply composite containing Kevlar in the warp and basalt in the weft direction. Whereas in inter-ply hybrid composite, with Kevlar as the loading face attained higher Stress, while composite with Basalt as the loading face attained higher strain. SEM micrographs revealed that Kevlar on the loading face can bear the impact with lesser delamination as compared to the Basalt on the loading face. Damage studies revealed that Kevlar fiber surface loading results in higher Stress as compared to basalt (brittle) surface loading with lower overall damage.
Syed Minhaj Saleem Kazmi - One of the best experts on this subject based on the ideXlab platform.
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axial Stress strain behavior of macro synthetic fiber reinforced recycled aggregate concrete
Cement & Concrete Composites, 2019Co-Authors: Syed Minhaj Saleem Kazmi, Muhammad Junaid Munir, Indubhushan Patnaikuni, Yingwu Zhou, Feng XingAbstract:Abstract This study aims to investigate the axial Stress-strain behavior of macro-synthetic fiber reinforced recycled aggregate concrete. Concrete cylinders reinforced with macro-synthetic fibers were tested under axial compression, with the variation of three different replacement ratios of recycled aggregates (i.e., 0, 50 and 100%) and three different dosages of macro polypropylene fibers (i.e., 0, 0.5 and 1% of volume of recycled aggregate concrete). A comparative study of the existing Stress-strain models for steel fiber reinforced normal and recycled aggregate concrete with the test results indicates that the Stress-strain behavior of steel fiber reinforced normal and recycled aggregate concrete can be well predicted by these existing models. No Stress-strain model for macro-synthetic fiber reinforced normal and recycled aggregate concrete has been developed. Based on the test results, a Stress-strain model is developed in this work by modifying the parameters of best performing Stress-strain model for steel fiber reinforced normal aggregate concrete. The proposed model can effectively predict the Stress-strain behavior of both steel and macro-synthetic fiber reinforced normal and recycled aggregate concrete. Test results show that the Peak Stress, Peak strain and ultimate strain of concrete specimens increase with the increase in fiber dosage and the addition of fibers has a better effect on recycled aggregate concrete and as compared to normal aggregate concrete.
Soheil Solhjoo - One of the best experts on this subject based on the ideXlab platform.
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determination of critical strain for initiation of dynamic recrystallization
Materials & Design, 2010Co-Authors: Soheil SolhjooAbstract:Abstract Using the work hardening rate–strain curves, an effective mathematical model has been developed to predict the Stress–strain curves of alloy steel during hot deformation up to the Peak Stress regardless of the level of the strain, weather smaller or larger than the critical strain. This model is expressed in terms of Peak Stress, Peak strain and one temperature-sensitive parameter, S . In addition, one new model, which is a function of Peak strain, was proposed to predict the critical strain for the initiation of dynamic recrystallization using the second derivative of work hardening rate with respect to Stress. Besides the theoretical study, the analysis is used to determine the Stress–strain curves and critical strain of 304 austenitic stainless steel. The predicted results were found to be in accord with the experimental data.
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analysis of flow Stress up to the Peak at hot deformation
Materials & Design, 2009Co-Authors: Soheil SolhjooAbstract:A mathematical model has been developed to predict Stress–strain curve up to the Peak Stress at hot deformation. This model is based on the linear estimation of work hardening rate-Stress curve up to the Peak Stress. This equation is expressed in terms of Peak Stress, Peak strain. In addition, in order to find the value of Peak strain, Zenner–Hollomon parameter is modified. The predicted results are found to be in accord with the experimental flow Stress curves which can be used to predict the required deformation forces in hot deformation processes.