The Experts below are selected from a list of 207 Experts worldwide ranked by ideXlab platform
D Tumac - One of the best experts on this subject based on the ideXlab platform.
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Predicting the performance of chain saw machines based on Shore scleroscope Hardness
Rock Mechanics and Rock Engineering, 2014Co-Authors: D TumacAbstract:Shore Hardness has been used to estimate several physical and mechanical properties of rocks over the last few decades. However, the number of researches correlating Shore Hardness with rock cutting performance is quite limited. Also, rather limited researches have been carried out on predicting the performance of chain saw machines. This study differs from the previous investigations in the way that Shore Hardness values (SH1, SH2, and deformation coefficient) are used to determine the field performance of chain saw machines. The measured Shore Hardness values are correlated with the physical and mechanical properties of natural stone samples, cutting parameters (normal force, cutting force, and specific energy) obtained from linear cutting tests in unrelieved cutting mode, and areal net cutting rate of chain saw machines. Two empirical models developed previously are improved for the prediction of the areal net cutting rate of chain saw machines. The first model is based on a revised chain saw penetration index, which uses SH1, machine weight, and useful arm cutting depth as predictors. The second model is based on the power consumed for only cutting the stone, arm thickness, and specific energy as a function of the deformation coefficient. While cutting force has a strong relationship with Shore Hardness values, the normal force has a weak or moderate correlation. Uniaxial compressive strength, Cerchar abrasivity index, and density can also be predicted by Shore Hardness values.
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Estimation of Rock Cuttability from Shore Hardness and Compressive Strength Properties
Rock Mechanics and Rock Engineering, 2007Co-Authors: D Tumac, N. Bilgin, C. Feridunoglu, H. ErginAbstract:Shore Hardness has been used to estimate some mechanical and physical properties of rocks for many years. This study differs from previous studies in a way that it is directly oriented to rock cuttability. Two Shore Hardness values ( SH _1 and SH _2) and a coefficient of deformation value ( K ) have been measured for 30 different rock samples. In the first stage of the study, optimum specific energy values for 16 different rock samples obtained from full-scale cutting tests were correlated with the Shore Hardness values of the same rock samples changing SH _1 values from 9 to 66 and SH _2 values from 25 to 83, with deformation coefficient values changing from 26 to 195. In the second stage, the performance of a roadheader used in the Küçüksu (Istanbul) tunnel was recorded in detail and the instantaneous cutting rate of the machine was determined. Then, the relationship between Shore Hardness values, deformation coefficient and the instantaneous cutting rate of the machine was determined for different formations encountered. It is concluded that there is a relationship between Shore Hardness values, optimum specific energy and compressive strength, which may be used to estimate the rock cuttability and the instantaneous cutting rates of roadheaders within certain limits of reliability.
S Parke - One of the best experts on this subject based on the ideXlab platform.
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an experimental and theoretical study of the effect of sample thickness on the Shore Hardness of elastomers
Dental Materials, 2010Co-Authors: Adel Siddiqui, M Ade, M P Patel, S ParkeAbstract:Abstract Objective The Shore Hardness test is a quick and convenient way to measure Hardness of elastomers. The test specifies that the specimen should be at least 6 mm thick; however, published work in the literature indicates that workers often use much thinner samples. The aim of this study was to investigate the effect of thickness on the measured Hardness of a range of dental elastomers and develop a theoretical relationship to predict the effect. Methods 7 dental silicone elastomers were selected to give a range of Hardness values. Shore A scale Hardness measurements were made on standard thickness samples, and those of lower thicknesses. A theoretical analysis was derived, whereby the effect of thickness of the sample on its measured Hardness can be predicted and was tested using the results obtained. Results The results show reasonable agreement between theoretical and experimental values. The measured Shore Hardness increased inversely with thickness, the effect being most pronounced with thin samples. Results ranged from 66.3 ± 1.6–80.9 ± 0.4 for 1 mm thick to 35.0 ± 1.7–69.1 ± 0.6 for the 6 mm thickness. Ratio of the measured Hardness of 1 mm/6 mm ranged from 1.97 for the softest material to 1.17 for the hardest. Significance Measurements obtained with a Shore A Hardness tester on samples of less than the specified 6 mm thickness will give erroneously high values, the error being greater as thickness decreases. The theoretical treatment proposed gives a basis on which data obtained from studies that used thinner specimens can be better analysed.
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the relationship between Shore Hardness of elastomeric dental materials and young s modulus
Dental Materials, 2009Co-Authors: Iranthi M Meththananda, S Parke, M P Patel, M AdeAbstract:Abstract Objectives Hardness of elastomers can be directly related to Young's modulus, a relationship that was investigated in detail by Gent in a paper in 1958. The aim of this study was to test this relationship for 13 dental elastomers (12 silicone and 1 polyether) using the equation derived by Gent and one from BS 903 (1950) that accounts for departures at low values. Methods The dental elastomers were subjected to tensile testing and Shore A scale Hardness measurements. Young's moduli were calculated from the Hardness values using the Gent equation and the BS 903 equation. These calculated values were then compared with values derived experimentally from the tensile tests. Results Hardness values were in the range 30.2 (±0.5)–62.9 (±0.8) with the corresponding calculated modulus values in the range 1.1–4.1 MPa and 0.9–4.3 MPa for the Gent and modified equations, respectively. Young's modulus values derived from the tensile data were in the range 0.8 (±0.3)–4.1 (±0.3) MPa, showing good agreement with those calculated from the Hardness values. Providing viscoelastic creep is minimal during the duration of the test, there is a reasonably well-defined relationship between Shore Hardness and Young's modulus in the Hardness range studied. Significance Simple, non-destructive Hardness measurements can be used to determine Young's modulus values. Such values are needed in any calculations of stress distributions in soft lining materials, e.g. by FEA.
M Ade - One of the best experts on this subject based on the ideXlab platform.
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an experimental and theoretical study of the effect of sample thickness on the Shore Hardness of elastomers
Dental Materials, 2010Co-Authors: Adel Siddiqui, M Ade, M P Patel, S ParkeAbstract:Abstract Objective The Shore Hardness test is a quick and convenient way to measure Hardness of elastomers. The test specifies that the specimen should be at least 6 mm thick; however, published work in the literature indicates that workers often use much thinner samples. The aim of this study was to investigate the effect of thickness on the measured Hardness of a range of dental elastomers and develop a theoretical relationship to predict the effect. Methods 7 dental silicone elastomers were selected to give a range of Hardness values. Shore A scale Hardness measurements were made on standard thickness samples, and those of lower thicknesses. A theoretical analysis was derived, whereby the effect of thickness of the sample on its measured Hardness can be predicted and was tested using the results obtained. Results The results show reasonable agreement between theoretical and experimental values. The measured Shore Hardness increased inversely with thickness, the effect being most pronounced with thin samples. Results ranged from 66.3 ± 1.6–80.9 ± 0.4 for 1 mm thick to 35.0 ± 1.7–69.1 ± 0.6 for the 6 mm thickness. Ratio of the measured Hardness of 1 mm/6 mm ranged from 1.97 for the softest material to 1.17 for the hardest. Significance Measurements obtained with a Shore A Hardness tester on samples of less than the specified 6 mm thickness will give erroneously high values, the error being greater as thickness decreases. The theoretical treatment proposed gives a basis on which data obtained from studies that used thinner specimens can be better analysed.
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the relationship between Shore Hardness of elastomeric dental materials and young s modulus
Dental Materials, 2009Co-Authors: Iranthi M Meththananda, S Parke, M P Patel, M AdeAbstract:Abstract Objectives Hardness of elastomers can be directly related to Young's modulus, a relationship that was investigated in detail by Gent in a paper in 1958. The aim of this study was to test this relationship for 13 dental elastomers (12 silicone and 1 polyether) using the equation derived by Gent and one from BS 903 (1950) that accounts for departures at low values. Methods The dental elastomers were subjected to tensile testing and Shore A scale Hardness measurements. Young's moduli were calculated from the Hardness values using the Gent equation and the BS 903 equation. These calculated values were then compared with values derived experimentally from the tensile tests. Results Hardness values were in the range 30.2 (±0.5)–62.9 (±0.8) with the corresponding calculated modulus values in the range 1.1–4.1 MPa and 0.9–4.3 MPa for the Gent and modified equations, respectively. Young's modulus values derived from the tensile data were in the range 0.8 (±0.3)–4.1 (±0.3) MPa, showing good agreement with those calculated from the Hardness values. Providing viscoelastic creep is minimal during the duration of the test, there is a reasonably well-defined relationship between Shore Hardness and Young's modulus in the Hardness range studied. Significance Simple, non-destructive Hardness measurements can be used to determine Young's modulus values. Such values are needed in any calculations of stress distributions in soft lining materials, e.g. by FEA.
Halina Gluchowska - One of the best experts on this subject based on the ideXlab platform.
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the effect of soft segment structure on the properties of novel thermoplastic polyurethane elastomers based on an unconventional chain extender
Polymer International, 2011Co-Authors: Anna Kultys, Magdalena Rogulska, Halina GluchowskaAbstract:Thermoplastic polyurethane elastomers (TPUs) are now widely used because of their excellent properties that include high tensile and tear strength, and good abrasion, impact and chemical resistance. TPUs are multiblock copolymers with alternating sequences of hard segments composed of diisocyanates and simple diols (chain extenders) and soft segments formed by polymer diols. Commonly used hard segments for TPUs are derived from 4,4 � -diphenylmethane diisocyanate (MDI) and aliphatic diols. The aim of our research was to examine the possibility of obtaining TPUs with good tensile properties and thermal stability by using an unconventional aliphatic-aromatic chain extender, containing sulfide linkages. Three series of novel TPUs were synthesized by melt polymerization from poly(oxytetramethylene) diol, poly(e-caprolactone) diol or poly(hexane-1,6-diyl carbonate) diol of number-average molecular weight of 2000 g mol −1 as soft segments, MDI and 3,3 � [methylenebis(1,4-phenylenemethylenethio)]dipropan-1-ol as a chain extender. The structure and basic properties of the polymers were examined using Fourier transfer infrared spectroscopy, X-ray diffraction, atomic force microscopy, differential scanning calorimetry, thermogravimetric analysis, Shore Hardness and tensile tests. It is possible to synthesize TPUs from the aliphatic-aromatic chain extender with good tensile properties (strength up to 42.6 MPa and elongation at break up to 750%) and thermal stability. Because the structure of the newly obtained TPUs incorporates sulfur atoms, the TPUs can exhibit improved antibacterial activity and adhesive properties. c � 2011 Society of Chemical Industry
Regina Mericskestern - One of the best experts on this subject based on the ideXlab platform.
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vinylsiloxanether a new impression material clinical study of implant impressions with vinylsiloxanether versus polyether materials
Clinical Implant Dentistry and Related Research, 2012Co-Authors: Norbert Enkling, Stefan Bayer, Peter Jöhren, Regina MericskesternAbstract:The performance of three elastomeric materials for the open monophase implant impressions technique was tested under the following clinical conditions: polyether (IM) and vinylsiloxanether without (ID) and with additional simultaneous splinting of the implant impression copings with a higher Shore Hardness A-silicone (IDF).