The Experts below are selected from a list of 15471 Experts worldwide ranked by ideXlab platform
Michael A. Mccarthy - One of the best experts on this subject based on the ideXlab platform.
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insights into complex rheological behaviour of carbon fibre peek from a novel numerical methodology incorporating fibre friction and Melt Viscosity
Composite Structures, 2018Co-Authors: Anne Deignan, Lukasz Figiel, Michael A. MccarthyAbstract:Abstract A recent rheological study of carbon-fibre-reinforced PEEK (CF/PEEK) demonstrated highly complex behaviour, involving phenomenological differences at low and high strain rates. To explain the behaviour, it was hypothesised that CF/PEEK responds as a yield-stress fluid at low strain rates, with boundary-lubricated, fibre-fibre friction determining the Viscosity, and as a viscous fluid at high strain rates, with polymer Melt Viscosity dominating the response. In this paper, a novel finite-element methodology, incorporating fibre friction and Melt Viscosity in the same model, is employed to study this hypothesis. Two-fibre models investigate how fibre friction and Melt Viscosity combine to produce an overall composite Viscosity. Representative-volume-element (RVE) models examine multi-fibre/Melt response, and demonstrate that inclusion of fibre friction produces the observed yield-stress behaviour at low strain rates, and viscous behaviour at high strain rates. Another phenomenon which affects rheological measurements of such composites is shear banding in the sample, which occurs in the yield-stress regime. This effect is demonstrated in the models, and analysis of load transfer between fibres and Melt explains how it arises, and how it leads to diminished values of measured Viscosity. The results pave the way for improved process models for high-throughput manufacturing processes such as Automated Tape Placement.
Daniele Giordano - One of the best experts on this subject based on the ideXlab platform.
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an expanded non arrhenian model for silicate Melt Viscosity a treatment for metaluminous peraluminous and peralkaline liquids
Chemical Geology, 2006Co-Authors: Donald B Dingwell, J K Russell, Daniele Giordano, A Mangiacapra, Marcel Potuzak, Claudia Romano, A Di MuroAbstract:We present new Viscosity measurements for Melts spanning a wide range of anhydrous compositions including: rhyolite, trachyte, moldavite, andesite, latite, pantellerite, basalt and basanite. Micropenetration and concentric cylinder viscometry measurements cover a Viscosity range of 10 −1 to 10 12 Pas and a temperature range from 700 to 1650 °C. These new measurements, combined with other published data, provide a high-quality database comprising ∼800 experimental data on 44 well-characterized Melt compositions. This database is used to recalibrate the model proposed by Giordano and Dingwell [Giordano, D., Dingwell, D. B., 2003a. Non-Arrhenian multicomponent Melt Viscosity: a model. Earth Planet. Sci. Lett. 208, 337–349] for predicting the Viscosity of natural silicate Melts. The present contribution clearly shows that: (1) the Viscosity (η)–temperature relationship of natural silicate liquids is very well represented by the VFT equation [log η=A+B/(T −C)] over the full range of Viscosity considered here, (2) the use of a constant high-T limiting value of Melt Viscosity (e.g., A) is fully consistent with the experimental data, (3) there are 3 different compositional suites (peralkaline, metaluminous and peraluminous) that exhibit different patterns in Viscosity, (4) the Viscosity of metaluminous liquids is well described by a simple mathematical expression involving the compositional parameter (SM) but the compositional dependence of Viscosity for peralkaline and peraluminous Melts is not fully controlled by SM. For these extreme compositions we refitted the model using a temperature-dependent parameter based on the excess of alkalies relative to alumina (e.g., AE/SM). The recalibrated model reproduces the entire database to within 5% relative
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a model for silicate Melt Viscosity in the system camgsi2o6 caal2si2o8 naalsi3o8
Geochimica et Cosmochimica Acta, 2005Co-Authors: J K Russell, Daniele GiordanoAbstract:Abstract Five hundred eighty-five Viscosity measurements on 40 Melt compositions from the ternary system CaMgSi2O6 (Di)-CaAl2Si2O8 (An)-NaAlSi3O8 (Ab) have been compiled to create an experimental database spanning a wide range of temperatures (660–2175°C). The Melts within this ternary system show near-Arrhenian to strongly non-Arrhenian properties, and in this regard are comparable to natural Melts. The database is used to produce a chemical model for the compositional and temperature dependence of Melt Viscosity in the Di-An-Ab system. We use the Vogel-Fulcher-Tammann equation (VFT: log η = A + B/(T − C)) to account for the temperature dependence of Melt Viscosity. We also assume that all silicate Melts converge to a common Viscosity at high temperature. Thus, A is independent of composition, and all compositional dependence resides in the parameters B and C. The best estimate for A is −5.06, which implies a high-temperature limit to Viscosity of 10-5.06 Pa s. The compositional dependence of B and C is expressed by 12 coefficients (bi=1,2.6, cj=1,2..6) representing linear (e.g., bi=1:3) and higher order, nonlinear (e.g., bi=4:6) contributions. Our results suggest a near-linear compositional dependence for B (
Anne Deignan - One of the best experts on this subject based on the ideXlab platform.
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insights into complex rheological behaviour of carbon fibre peek from a novel numerical methodology incorporating fibre friction and Melt Viscosity
Composite Structures, 2018Co-Authors: Anne Deignan, Lukasz Figiel, Michael A. MccarthyAbstract:Abstract A recent rheological study of carbon-fibre-reinforced PEEK (CF/PEEK) demonstrated highly complex behaviour, involving phenomenological differences at low and high strain rates. To explain the behaviour, it was hypothesised that CF/PEEK responds as a yield-stress fluid at low strain rates, with boundary-lubricated, fibre-fibre friction determining the Viscosity, and as a viscous fluid at high strain rates, with polymer Melt Viscosity dominating the response. In this paper, a novel finite-element methodology, incorporating fibre friction and Melt Viscosity in the same model, is employed to study this hypothesis. Two-fibre models investigate how fibre friction and Melt Viscosity combine to produce an overall composite Viscosity. Representative-volume-element (RVE) models examine multi-fibre/Melt response, and demonstrate that inclusion of fibre friction produces the observed yield-stress behaviour at low strain rates, and viscous behaviour at high strain rates. Another phenomenon which affects rheological measurements of such composites is shear banding in the sample, which occurs in the yield-stress regime. This effect is demonstrated in the models, and analysis of load transfer between fibres and Melt explains how it arises, and how it leads to diminished values of measured Viscosity. The results pave the way for improved process models for high-throughput manufacturing processes such as Automated Tape Placement.
Lukasz Figiel - One of the best experts on this subject based on the ideXlab platform.
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insights into complex rheological behaviour of carbon fibre peek from a novel numerical methodology incorporating fibre friction and Melt Viscosity
Composite Structures, 2018Co-Authors: Anne Deignan, Lukasz Figiel, Michael A. MccarthyAbstract:Abstract A recent rheological study of carbon-fibre-reinforced PEEK (CF/PEEK) demonstrated highly complex behaviour, involving phenomenological differences at low and high strain rates. To explain the behaviour, it was hypothesised that CF/PEEK responds as a yield-stress fluid at low strain rates, with boundary-lubricated, fibre-fibre friction determining the Viscosity, and as a viscous fluid at high strain rates, with polymer Melt Viscosity dominating the response. In this paper, a novel finite-element methodology, incorporating fibre friction and Melt Viscosity in the same model, is employed to study this hypothesis. Two-fibre models investigate how fibre friction and Melt Viscosity combine to produce an overall composite Viscosity. Representative-volume-element (RVE) models examine multi-fibre/Melt response, and demonstrate that inclusion of fibre friction produces the observed yield-stress behaviour at low strain rates, and viscous behaviour at high strain rates. Another phenomenon which affects rheological measurements of such composites is shear banding in the sample, which occurs in the yield-stress regime. This effect is demonstrated in the models, and analysis of load transfer between fibres and Melt explains how it arises, and how it leads to diminished values of measured Viscosity. The results pave the way for improved process models for high-throughput manufacturing processes such as Automated Tape Placement.
Tony Mcnally - One of the best experts on this subject based on the ideXlab platform.
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shape stabilised phase change materials based on a high Melt Viscosity hdpe and paraffin waxes
Applied Energy, 2016Co-Authors: Pam Basheer, Yun Bai, Wei Sha, Tony McnallyAbstract:Shape stabilised phase change materials (SSPCMs) based on a high density poly(ethylene)(hv-HDPE) with high (H-PW, Tm=56–58°C) and low (L-PW, Tm=18–23°C) Melting point paraffin waxes were readily prepared using twin-screw extrusion. The thermo-physical properties of these materials were assessed using a combination of techniques and their suitability for latent heat thermal energy storage (LHTES) assessed. The Melt processing temperature (160°C) of the HDPE used was well below the onset of thermal decomposition of H-PW (220°C), but above that for L-PW (130°C), although the decomposition process extended over a range of 120°C and the residence time of L-PW in the extruder was <30s. The SSPCMs prepared had latent heats up to 89J/g and the enthalpy values for H-PW in the respective blends decreased with increasing H-PW loading, as a consequence of co-crystallisation of H-PW and hv-HDPE. Static and dynamic mechanical analysis confirmed both waxes have a plasticisation effect on this HDPE. Irrespective of the mode of deformation (tension, flexural, compression) modulus and stress decreased with increased wax loading in the blend, but the H-PW blends were mechanically superior to those with L-PW.
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Shape stabilised phase change materials based on a high Melt Viscosity HDPE and paraffin waxes
Applied Energy, 2016Co-Authors: Pam Basheer, Yun Bai, Wei Sha, Tony McnallyAbstract:Shape stabilised phase change materials (SSPCMs) based on a high density poly(ethylene)(hv-HDPE) with high (H-PW, Tm=56–58°C) and low (L-PW, Tm=18–23°C) Melting point paraffin waxes were readily prepared using twin-screw extrusion. The thermo-physical properties of these materials were assessed using a combination of techniques and their suitability for latent heat thermal energy storage (LHTES) assessed. The Melt processing temperature (160°C) of the HDPE used was well below the onset of thermal decomposition of H-PW (220°C), but above that for L-PW (130°C), although the decomposition process extended over a range of 120°C and the residence time of L-PW in the extruder was