The Experts below are selected from a list of 27918 Experts worldwide ranked by ideXlab platform
Claude Feldman Pambou Nziengui - One of the best experts on this subject based on the ideXlab platform.
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notched beam Creep of douglas fir and white fir in outdoor conditions experimental study
Construction and Building Materials, 2019Co-Authors: Claude Feldman Pambou Nziengui, Rostand Moutou Pitti, Eric Fournely, Joseph Gril, Gael Godi, Samuel IkogouAbstract:Abstract The impact of variations of relative humidity, temperature and moisture content on the Creep of notched beams of Douglas fir and white fir are investigated. Indoor static 4-points bending Tests are followed by outdoor Creep Tests of notched beams designed to trigger the breakage mode associated with the use of notched ends. The dimensions of wood specimens follow Eurocode requirements. The maximum load applied to outdoor Creep Tests is derived from the failure load obtained during indoor instantaneous Tests. The results show that the variations of the relative humidity and temperature, coupled with the loading, play a key role in the lifetime of timber, as they accelerate its aging. In addition, the link between the changes of climatic parameters and the damage of the beams and the limit of their lifetime as structure is shown.
Samuel Ikogou - One of the best experts on this subject based on the ideXlab platform.
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notched beam Creep of douglas fir and white fir in outdoor conditions experimental study
Construction and Building Materials, 2019Co-Authors: Claude Feldman Pambou Nziengui, Rostand Moutou Pitti, Eric Fournely, Joseph Gril, Gael Godi, Samuel IkogouAbstract:Abstract The impact of variations of relative humidity, temperature and moisture content on the Creep of notched beams of Douglas fir and white fir are investigated. Indoor static 4-points bending Tests are followed by outdoor Creep Tests of notched beams designed to trigger the breakage mode associated with the use of notched ends. The dimensions of wood specimens follow Eurocode requirements. The maximum load applied to outdoor Creep Tests is derived from the failure load obtained during indoor instantaneous Tests. The results show that the variations of the relative humidity and temperature, coupled with the loading, play a key role in the lifetime of timber, as they accelerate its aging. In addition, the link between the changes of climatic parameters and the damage of the beams and the limit of their lifetime as structure is shown.
Mehdi Ostadhassan - One of the best experts on this subject based on the ideXlab platform.
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Creep behavior of shale nanoindentation vs triaxial Creep Tests
Rock Mechanics and Rock Engineering, 2021Co-Authors: Kouqi Liu, F S Rassouli, Bo Liu, Mehdi OstadhassanAbstract:In this study, three shale samples from the Wolfcamp Formation in Permian basin were selected and studied for Creep behavior using two different methods at macro- and micro-scale: triaxial and nanoindentation Creep Tests. The triaxial Creep test showed the effects of axial differential stress on the Creep behavior of shale rocks including the strain and contact Creep modulus. As the axial differential stress increased, the Creep strain value presented an increasing trend. Additionally, based on the grid nanoindentation Creep experiments, three different mechanical phases were recognized in these samples; Phase 1: soft mechanical phase, Phase 2: intermediate, and Phase 3: hard mechanical phase. Based on the micro-scale results, at the same Creep time periods, phase 1 (clay + organic matter) was found to have a smaller contact Creep modulus and larger Creep strain value than Phase 3 (quartz). Comparing the results from these two scales of measurements, the contact Creep modulus from the triaxial test and the homogenized contact Creep modulus from nanoindentation experiments showed some discrepancies. Based on the samples in this study, the contact Creep modulus from the triaxial test varied from 0.5 to 4 times the value of the nanoindentation test. The differences between the contact Creep modulus from the nanoindentation and triaxial test could be due to the Creep strain amplitude. Considering Sample 1 as an example, the Creep strain amplitude under the nanoindentation is inferred to be 0.069 which is not equal to the Creep strain amplitude from the triaxial test (0.0052 under differential stress of 30 MPa). Ultimately, the contact Creep modulus from the nanoindentation can fluctuate based on the samples’ content, while the reason for this is still a question that needs further study. Overall, this study is a preliminary investigation to help us understand how nanomechanical data in complex geomaterials can relate to traditional triaxial data.
M Goken - One of the best experts on this subject based on the ideXlab platform.
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new flat punch indentation Creep testing approach for characterizing the local Creep properties at high temperatures
Materials & Design, 2019Co-Authors: D Matschkalamberger, Markus Kolb, Steffen Neumeier, S Gao, Alexander Hartmaier, Karsten Durst, M GokenAbstract:Abstract An indentation Creep testing approach has been developed which allows measuring Creep properties at high temperatures. In contrast to existing indentation or impression Creep experiments, the approach described here allows to achieve a quite high spatial resolution, as flat punch indenters with a diameter of only 20 μm are used. First indentation Creep Tests have been performed on single crystalline nickel and nickel binary solid solution alloys with Re, Ta or W as alloying elements, respectively. The indentation Creep Tests have been carried out at a temperature of 650 °C and stress levels in the range of 85 to 400 MPa. Using crystal plasticity finite element modeling, the indentation Creep response is converted into equivalent uniaxial Creep properties. It is shown that the conversion parameters, evaluated for differently oriented single crystals, can be chosen independently of the Creep rate exponent in the power law Creep regime. It is found that the indentation Creep results agree well with conventional uniaxial Creep Tests. Furthermore, the results show that Ta is the most effective solid solution strengthener of all tested solid-solution strengtheners at 650 °C because of the large atomic size mismatch, followed by W and Re.
Shin-ichi Komazaki - One of the best experts on this subject based on the ideXlab platform.
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evaluation of Creep rupture strength of high nitrogen ferritic heat resistant steels using small punch Creep testing technique
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2016Co-Authors: Shin-ichi KomazakiAbstract:Abstract The development of next generation ultra-heat-resistant ferritic steels for the future advanced thermal power plants which operate in excess of 700 °C are currently in progress in Japan. The small punch (SP) Creep testing technique which uses miniature specimens has been applied to evaluate Creep rupture strength of newly developed high nitrogen ferritic steels. The SP Creep Tests have been carried out on different grades of high nitrogen ferritic steels in the temperature range of 600–800 °C, under different loads in the range of 70–400 N, using specimens of dimension ∅8 mm x 0.5 mm. The SP Creep rupture results of high nitrogen ferritic steels have been compared with that of conventional steel (Gr.91). The high nitrogen steels exhibited higher Creep rupture strength when compared to the Gr.91. The Creep rupture results obtained from SP Creep Tests were correlated to the uniaxial Creep rupture results obtained from conventional Creep Tests using a stress conversion coefficient of 2.05. The paper investigates the applicability of SP Creep testing technique for the evaluation of Creep rupture strength of high nitrogen ferritic heat-resistant steels.