101 results found
Hagan EWS, Charalambides MN, Young CRT, et al., 2015, The effects of strain rate and temperature on commercial acrylic artist paints aged one year to decades, Applied Physics A - Materials Science & Processing, Vol: 121, Pages: 823-835, ISSN: 1432-0630
Acrylic artist paints are viscoelastic composites containing a high molecular weight copolymer, pigment and a variety of additives. The glass transition temperature of the latex binder is typically slightly below ambient conditions, giving mechanical properties that are strongly dependent on strain rate and temperature. In previous work, the viscoelastic behaviour of custom-formulated latex artist paints was reported for films with known volume fractions of pigment using data from uniaxial tensile tests at different strain rates and temperatures. Secant Young’s modulus and failure strain master curves were constructed for each film through time-temperature superposition, allowing predictions beyond the experimental timescale at a selected reference temperature. A similar analysis is now presented for a small set of commercial artist paints tested at ages of 1 and 27 years. Experimental shift factor values are reported with fits to the Arrhenius, WLF and Vogel Fulcher equations, along with a comparison with published data for acrylic polymers. The tensile results highlight a spectrum of properties that acrylic paints may exhibit—brittle glass to hyperelastic—depending on the conditions during deformation. Strong similarities are shown between products from different manufacturers, and the findings suggest a high degree of stability with age. A method for predicting failure as a function of strain rate and temperature is also presented, and the methodology gives a framework for investigating other artist materials and the factors influencing their mechanical properties.
Arora H, Tarleton E, Li-Mayer J, et al., 2015, Modelling the damage and deformation process in a plastic bonded explosive microstructure under tension using the finite element method, Computational Materials Science, Vol: 110, Pages: 91-101, ISSN: 0927-0256
Modelling the deformation and failure processes occurring in polymer bonded explosives (PBX)and other energetic materials is of great importance for processing methods and lifetime storagepurposes. Crystal debonding is undesirable since this can lead to contamination and a reductionin mechanical properties. An insensitive high explosive (PBX-1) was the focus of the study.This binary particulate composite consists of (TATB) filler particles encapsulated in a polymericbinder (KELF800). The particle/matrix interface was characterised with a bi-linear cohesive law,the filler was treated as elastic and the matrix as visco-hyperelastic. Material parameters weredetermined experimentally for the binder and the cohesive parameters were obtained previouslyfrom Williamson et al. (2014) and Gee et al. (2007) for the interface. Once calibrated, the materiallaws were implemented in a finite element model to allow the macroscopic response of thecomposite to be simulated. A finite element mesh was generated using a SEM image to identifythe filler particles which are represented as a set of 2D polygons. Simulated microstructureswere also generated with the same size distribution and volume fraction only with the idealisedassumption that the particles are a set of circles in 2D and spheres in 3D. The various modelresults were compared and a number of other variables were examined for their influence on theglobal deformation behaviour such as strain rate, cohesive parameters and contrast between fillerand matrix modulus. The overwhelming outcome is that the geometry of the particles plays acrucial role in determining the onset of failure and the severity of fracture in relation to whetherit is a purely local or global failure. The model was validated against a set of uniaxial tensiletests on PBX-1 and it was found that it predicted the initial modulus and failure stress and strainwell.Keywords: Particulate composites, High volume fraction, Finite Element Analysis,Micromechanics, Fract
Zhang R, 2015, Microstructure-property relationships in alumina trihydrate filled poly (methyl methacrylate) composite materials, 2015 Global Conference on Polymer and Composite Materials (PCM 2015), Publisher: IOP Publishing: Conference Series, ISSN: 1757-899X
The mechanical properties (Young's modulus and fracture toughness) of composite made from a poly (methyl methacrylate) (PMMA) matrix filled with alumina trihydrate(ATH) are reported. The experiments were performed using flexural tests and single edge notched bend (SENB) tests. The composites samples were tested at a range of filler volume fractions (34.7%, 39.4% and 44.4%) and mean filler diameters (8 pm, 15 pm and 25 pm). The data of Young's modulus agreed well with the results of Lielens model and finite element analysis (FEA) model.
Forte AE, D'Amico F, Charalambides MN, et al., 2015, Modelling and experimental characterisation of the rate dependent fracture properties of gelatine gels, FOOD HYDROCOLLOIDS, Vol: 46, Pages: 180-190, ISSN: 0268-005X
Mohammed IK, Charalambides MN, Williams JG, et al., 2015, Modelling Deformation and Fracture in Confectionery Wafers, International Conference of Computational Methods in Sciences and Engineering (ICCMSE), Publisher: AMER INST PHYSICS, Pages: 289-292, ISSN: 0094-243X
The aim of this research is to model the deformation and fracture behaviour of brittle wafers often used in chocolate confectionary products. Three point bending and compression experiments were performed on beam and circular disc samples respectively to determine the 'apparent' stress-strain curves in bending and compression. The deformation of the wafer for both these testing types was observed in-situ within an SEM. The wafer is modeled analytically and numerically as a composite material with a core which is more porous than the skins. X-ray tomography was used to generate a three dimensional volume of the wafer microstructure which was then meshed and used for quantitative analysis. A linear elastic material model, with a damage function and element deletion, was used and the XMT generated architecture was loaded in compression. The output from the FE simulations correlates closely to the load-deflection deformation observed experimentally.
Mohammed MAP, Tarleton E, Charalambides MN, et al., 2015, A Micromechanics Model for Bread Dough, International Conference of Computational Methods in Sciences and Engineering (ICCMSE), Publisher: American Institute of Physics, Pages: 305-309, ISSN: 0094-243X
The mechanical behaviour of dough and gluten was studied in an effort to investigate whether bread dough canbe treated as a two phase (starch and gluten) composite material. The dough and gluten show rate dependent behaviourunder tension, compression and shear tests, and non-linear unloading-reloading curves under cyclic compression tests.There is evidence from cryo-Scanning Electron Microscopy (SEM) that damage in the form of debonding between starchand gluten occurs when the sample is stretched. A composite finite element model was developed using starch as fillerand gluten as matrix. The interaction between the starch and gluten was modelled as cohesive contact. The finite elementanalysis predictions agree with trends seen in experimental test data on dough and gluten, further evidence that debondingof starch and gluten is a possible damage mechanism in dough.
Kinloch AJ, Mohammed IK, Charalambides MN, 2014, Modelling the interfacial peeling of pressure-sensitive adhesives, Journal of Non-Newtonian Fluid Mechanics, Vol: 222, Pages: 141-150, ISSN: 1873-2631
Peel tests were performed using specimens which consisted of a polyester backing membrane supporting an acrylic pressure-sensitive adhesive adhered to a polyethylene substrate. Interfacial separation of the PSA from the polyethylene substrate was observed. Finite element (FE) peeling simulations were conducted which modelled the backing-membrane as an elasto-plastic power-law material, the adhesive as a viscoelastic material and the interfacial properties with a cohesive zone model (CZM). The material properties of the backing membrane and the pressure-sensitive adhesive were measured from tensile and stress relaxation experiments. The cohesive zone parameters were calculated analytically from the peel test data, as well as being measured directly from independent poker-chip probe tack tests. The numerical results from the CZM/FE simulations and the experimental values of the peel forces as a function of the peel angle were found to be in good agreement.
Mohammed IK, Charalambides MN, Williams JG, et al., 2014, Modelling the microstructural evolution and fracture of a brittle confectionery wafer in compression, INNOVATIVE FOOD SCIENCE & EMERGING TECHNOLOGIES, Vol: 24, Pages: 48-60, ISSN: 1466-8564
Tantideeravit S, Charalambides MN, Balint DS, et al., 2013, Prediction of delamination in multilayer artist paints under low amplitude fatigue loading, ENGINEERING FRACTURE MECHANICS, Vol: 112, Pages: 41-57, ISSN: 0013-7944
Mohammed IK, Charalambides MN, Williams JG, et al., 2013, Modelling the deformation of a confectionery wafer as a non-uniform sandwich structure, JOURNAL OF MATERIALS SCIENCE, Vol: 48, Pages: 2462-2478, ISSN: 0022-2461
Mohammed MAP, Tarleton E, Charalambides MN, et al., 2013, Mechanical characterization and micromechanical modeling of bread dough, JOURNAL OF RHEOLOGY, Vol: 57, Pages: 249-272, ISSN: 0148-6055
Arora H, Charalambides MN, Tarleton E, et al., 2013, An image based approach to modelling plastic bonded explosives (PBX) on the micro scale, Pages: 5391-5397
Tarleton E, Charalambides MN, Leppard C, 2012, Image-based modelling of binary composites, 21st International Workshop on Computational Mechanics of Materials (IWCMM), Publisher: ELSEVIER SCIENCE BV, Pages: 183-186, ISSN: 0927-0256
Hagan EWS, Charalambides MN, Young CRT, et al., 2011, Influence of the inorganic phase concentration and geometry on the viscoelastic properties of latex coatings through the glass-transition, POLYMER, Vol: 52, Pages: 1662-1673, ISSN: 0032-3861
Mohammed MAP, Tarleton E, Charalambides MN, et al., 2011, A composite model for wheat flour dough under large deformation, 11th International Congress on Engineering and Food (ICEF), Publisher: ELSEVIER SCIENCE BV, Pages: 492-498, ISSN: 2211-601X
Stapountzi OA, Charalambides MN, Williams JG, 2011, The Fracture Toughness of a Highly Filled Polymer Composite, Symposium on Recent Advances in Mechanics, Publisher: SPRINGER-VERLAG BERLIN, Pages: 447-459
Mohammeda IK, Charalambides MN, Williams JG, et al., 2011, Modelling deformation and fracture in confectionery wafers, 11th International Congress on Engineering and Food (ICEF), Publisher: ELSEVIER SCIENCE BV, Pages: 499-504, ISSN: 2211-601X
Hagan EWS, Charalambides MN, Young CRT, et al., 2010, Viscoelastic properties of latex paint films in tension: Influence of the inorganic phase and surfactants, PROGRESS IN ORGANIC COATINGS, Vol: 69, Pages: 73-81, ISSN: 0300-9440
Gamonpilas C, Charalambides MN, Williams JG, et al., 2010, PREDICTING THE MECHANICAL BEHAVIOUR OF STARCH GELS THROUGH INVERSE ANALYSIS OF INDENTATION DATA, APPLIED RHEOLOGY, Vol: 20, ISSN: 1430-6395
Gamonpilas C, Charalambides MN, Williams JG, 2009, Determination of large deformation and fracture behaviour of starch gels from conventional and wire cutting experiments, JOURNAL OF MATERIALS SCIENCE, Vol: 44, Pages: 4976-4986, ISSN: 0022-2461
Stapountzi OA, Charalambides MN, Williams JG, 2009, Micromechanical models for stiffness prediction of alumina trihydrate (ATH) reinforced poly (methyl methacrylate) (PMMA): Effect of filler volume fraction and temperature, COMPOSITES SCIENCE AND TECHNOLOGY, Vol: 69, Pages: 2015-2023, ISSN: 0266-3538
Hagan EWS, Charalambides MN, Young CT, et al., 2009, Tensile properties of latex paint films with TiO2 pigment, MECHANICS OF TIME-DEPENDENT MATERIALS, Vol: 13, Pages: 149-161, ISSN: 1385-2000
Goh SM, Alten S, van Dalen G, et al., 2008, The mechanical properties of model-compacted tablets, JOURNAL OF MATERIALS SCIENCE, Vol: 43, Pages: 7171-7178, ISSN: 0022-2461
Gamonpilas C, Charalambides MN, Williams JG, et al., 2008, Characterisation of fracture behaviour of starch gels using conventional fracture mechanics and wire cutting tests, 15th International Congress on Rheology/80th Annual Meeting of the Society-of-Rheology, Publisher: AMER INST PHYSICS, Pages: 1232-+, ISSN: 0094-243X
Gamonpilas C, Charalambides MN, Williams JG, et al., 2008, Characterisation of large deformation behaviour of starch gels using compression and indentation techniques, 15th International Congress on Rheology/80th Annual Meeting of the Society-of-Rheology, Publisher: AMER INST PHYSICS, Pages: 1189-+, ISSN: 0094-243X
Xiao W, Charalambides MN, Williams JG, 2007, Sheeting of wheat flour dough, INTERNATIONAL JOURNAL OF FOOD SCIENCE AND TECHNOLOGY, Vol: 42, Pages: 699-707, ISSN: 0950-5423
OA Stapountzi, M Charalambides, JG Williams, 2007, EFFECT OF TEMPERATURE AND FILLER VOLUME FRACTION ON THE STIFFNESS OF PARTICLE REINFORCED POLY- METHYL METHACRYLATE, 13th International Conference on Experimental Mechanics(ICEM13), Publisher: Springer, Dordrecht, The Netherlands
Xiao W, Charalambides MN, Williams JG, 2007, Sheeting of wheat flour dough, International Journal of Food Science and Technology, Vol: 42, Pages: 699-707, ISSN: 0950-5423
Charalambides MN, Wanigasooriya L, Williams JG, et al., 2006, Large deformation extensional rheology of bread dough, RHEOL ACTA, Vol: 46, Pages: 239-248, ISSN: 0035-4511
<p>The stress-strain curves of bread dough were derived under uniaxial compression, uniaxial tension and equi-biaxial tension loading conditions. In uniaxial compression, a lubricant was used to eliminate frictional effects between the loading platens and the sample. In uniaxial tension, cylindrical samples with thin flat discs at both ends ('I' samples) were tested. The discs at both ends were allowed to air-dry and were subsequently glued onto the loading platens. In equi-biaxial tension, a thin disc of dough was inflated into a bubble using pressurised air. The thickness at the top of the bubble was measured by shining a light through the walls of the bubble and recording the change in light intensity as the wall becomes thinner. All methods ensured that uniform deformation was obtained. Stress and strain were accurately evaluated using image analysis techniques. The tests were performed at various strain rates and speeds that defined the time dependence of the material. A non-linear viscoelastic model based on the Prony series and Van der Waals hyperelasticity was used to predict all test data. The model had a total of five material parameters and two time constants, which were set to represent the actual time scales of the experiments. A reasonable agreement between the experimental data and the chosen material model was observed.</p>
Charalambides MN, Wanigasooriya L, Williams JG, et al., 2006, Large deformation extensional rheology of bread dough, Rheologica Acta, Vol: 46, Pages: 239-248, ISSN: 0035-4511
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