Journal articles: 'Stress block parameters'

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Singh, Brijesh, Vikas Patel, P. N. Ojha, and V. V. Arora. "Analysis of stress block parameters for high strength concrete." Journal of Asian Concrete Federation 6, no. 1 (June 30, 2020): 1–9. http://dx.doi.org/10.18702/acf.2020.6.6.1.

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Singh, Brijesh, Vikas Patel, P. N. Ojha, and V. V. Arora. "Analysis of stress block parameters for high strength concrete." Journal of Asian Concrete Federation 6, no. 1 (June 30, 2020): 1–9. http://dx.doi.org/10.18702/acf.2020.6.6.1.1.

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Bae, Baek-il, Hyun-Ki Choi, and Chang-Sik Choi. "Stress Block Parameters for Steel Fiber Reinforced Reactive Powder Concrete." Advanced Science Letters 13, no. 1 (June 30, 2012): 115–19. http://dx.doi.org/10.1166/asl.2012.3832.

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Oztekin, Ertekin, Selim Pul, and Metin Husem. "Determination of rectangular stress block parameters for high performance concrete." Engineering Structures 25, no. 3 (February 2003): 371–76. http://dx.doi.org/10.1016/s0141-0296(02)00172-4.

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Braga, Franco, Rosario Gigliotti, Michelangelo Laterza, and Michele D'Amato. "An Analytical Formulation of Stress-Block Parameters for Confined Concrete!" Open Construction and Building Technology Journal 2, no. 1 (September 26, 2008): 156–65. http://dx.doi.org/10.2174/1874836800802010156.

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Akbar, Fachreza, Ari Wibowo, and Wisnumurti Wisnumurti. "Preloaded Reinforced Concrete Beam Stress Block Parameters : A Preliminary Approach." Rekayasa Sipil 12, no. 1 (February 20, 2018): 1–9. http://dx.doi.org/10.21776/ub.rekayasasipil.2018.012.01.1.

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Assi, Nizar, Husain Al-Gahtani, and Mohammed A. Al-Osta. "Numerical Investigation of Stress Block for High Strength Concrete Columns." Civil Engineering Journal 6, no. 5 (May 1, 2020): 974–96. http://dx.doi.org/10.28991/cej-2020-03091522.

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This paper is intended to investigate the stress block for high strength concrete (HSC) using the finite element model (FEM) and analytical approach. New stress block parameters were proposed for HSC including the stress intensity factor (α1) and the depth factor (β1) based on basic equilibrium equations. A (3D) finite element modeling was developed for the columns made of HSC using the comprehensive code ABAQUS. The proposed stress parameters were validated against the experimental data found in the literature and FEM. Thereafter, the proposed stress block for HSC was used to generate interaction diagrams of rectangular and circular columns subjected to compression and uniaxial bending. The effects of the stress block parameters of HSC on the interaction diagrams were demonstrated. The results showed that a good agreement is obtained between the failure loads using the finite element model and the analytical approach using the proposed parameters, as well as the achievement of a close agreement with experimental observation. It is concluded that the use of proposed parameters resulted in a more conservative estimation of the failure load of columns. The effect of the stress depth factor is considered to be minor compared with the effect of the intensity factor.

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Yeon, Kyu-Seok, Jai-Chul Yi, and Yoon-Sang Choi. "Stress-Strain Relation and Stress Block Parameters on Flexural Compressive Strength of Polymer Concrete." Journal of The Korean Society of Agricultural Engineers 50, no. 5 (September 30, 2008): 29–37. http://dx.doi.org/10.5389/ksae.2008.50.5.029.

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Zhang, Xiu Fang, and Shi Lang Xu. "Rectangular Stress-Block Parameters for Bending Design of Reinforced UHTCC Beam." Advanced Materials Research 243-249 (May 2011): 32–40. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.32.

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The full replacement of plain concrete with ultra-high toughness cementitious composite (UHTCC) in structural members can obtain the enhanced structural performance over traditional concrete structures because of its prominent advantages such as the markedly ductile deformation capacity after post-cracking and excellent damage tolerance ability. In the current article, aimed at setting up the theoretical formula for the practical use in the bending design of reinforced beam made of UHTCC, the equivalent parameters introduced in rectangular stress block approach are analytically determined. Two existing models in compression for UHTCC, i.e., bilinear model and parabolic line then horizontal line (nonlinear model) are adopted in the derivation of the equivalent parameters. By comparing moment-curvature curve obtained from the experiment with the calculated one, the nonlinear model is verified to be rational and could predict bending capacity with sufficient accuracy. Further comparison between moment-curvature curves calculated according to two compression models shows that the nonlinear model can give a bending response prediction with almost the same accuracy as the bilinear model. Finally, it is suggested that, in the case that nonlinear compression model is adopted for the compressive behavior in UHTCC, the equivalent parameters α=0.8 and β=1.0 could be used to estimate ultimate load bearing capacity of reinforced UHTCC beam.

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Karthik, Madhu M., and John B. Mander. "Stress-Block Parameters for Unconfined and Confined Concrete Based on a Unified Stress-Strain Model." Journal of Structural Engineering 137, no. 2 (February 2011): 270–73. http://dx.doi.org/10.1061/(asce)st.1943-541x.0000294.

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Neethu, Elizabeth John, and S. R. Akhil Raj. "Evaluation of Stress Block Parameters for Steel Fibre Reinforced SCC with Recycled Concrete Aggregate." Applied Mechanics and Materials 857 (November 2016): 76–81. http://dx.doi.org/10.4028/www.scientific.net/amm.857.76.

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Stress block parameters are predominantly used in the design of concrete structural members and offer a convenient method to arrive at the flexural capacity. The objective is to find the equivalent stress block parameters namely, the effective average concrete ratio and the stress block depth factor for Self Compacting Concrete with recycled aggregate (RSCC) and SCC with recycled aggregate incorporating steel fibres (SFRSCC) . SCC is defined as a highly workable concrete which flows by its own weight. Sustainability of SCC can be improved by replacing mineral aggregates by industrial waste like rubber, recycled aggregate, granite powder etc. An experimental investigation was carried out on the stress strain characteristics of SCC by partially replacing 25, 50, 75 and 100 % of coarse aggregate by recycled aggregate (RSCC) for varying design strength 30, 40, 50 MPa under monotonically increasing axial loading. The behavior of SCC with 100 % recycled aggregate incorporating steel fibres with different volumetric ratios is also explored. A total of 72 cylinders were prepared to develop a stress strain model for RSCC and SFRSCC. The results were compared with the existing models used for SCC and recycled aggregate and it indicates that Saenz model was found applicable for finding the stress block parameters. The proposed parameters were found to be lesser than the values for normal concrete specified by IS 456 and that these parameters could be used to determine the flexural strength of members made using the above composites.

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Chen, Rong, Wang Ping, and Hao Xu. "Influence of Structural Parameters on Mechanical Properties of Double-Block Ballastless Track." Applied Mechanics and Materials 84-85 (August 2011): 188–93. http://dx.doi.org/10.4028/www.scientific.net/amm.84-85.188.

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A high degree of integrity is the most remarkable feature that makes double-block ballastless track different from other ballastless track structure. Based on the beam/plate theory on elastic foundation, influences of several structural parameters (such as size of track slab and support layer, support stiffness of the subgrade, etc) on stress of the ballastless track system under the axle load of 300kN were studied in order to obtain further understanding of the mechanic performance of double-block ballastless track under the train load. Results show that: structure of double-layer combined structure should be adopted to decrease the stress of each layer of ballastless track; the width of support layer should be less than 3.6m; because the ratio of track slab stress to support layer stress is larger than the ratio of their strength, the width of track slab in the double-layer separated structure should be 280mm or less.

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Tran, Tung T., Thong M. Pham, and Hong Hao. "Rectangular Stress-block Parameters for Fly-ash and Slag Based Geopolymer Concrete." Structures 19 (June 2019): 143–55. http://dx.doi.org/10.1016/j.istruc.2019.01.006.

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Prachasaree, Woraphot, Suchart Limkatanyu, Abideng Hawa, and Agarat Samakrattakit. "Development of Equivalent Stress Block Parameters for Fly-Ash-Based Geopolymer Concrete." Arabian Journal for Science and Engineering 39, no. 12 (November 11, 2014): 8549–58. http://dx.doi.org/10.1007/s13369-014-1447-2.

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15

CAMACHO, J. S., B. G. LOGULLO, G. A. PARSEKIAN, and P. R. N. SOUDAIS. "The influence of grouting and reinforcement ratio in the concrete block masonry compressive behavior." Revista IBRACON de Estruturas e Materiais 8, no. 3 (June 2015): 341–64. http://dx.doi.org/10.1590/s1983-41952015000300006.

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This paper presents an experimental investigation on the compressive strength and stress-strain curves of concrete block masonry with varying block and grout strengths and reinforcement ratio. The three-block prisms, built with 8.5 and 15.0 MPa blocks, were tested hollow and filled with 17.0 and 30.0 MPa compressive strength grouts. In addition, prisms and walls with reinforcement rates of 0.15%, 0.40% and 1.0 % were also tested. With the results, it was possible to measure the compressive strength and stress-strain behavior of masonry with inclusion of different grout and reinforcement components, giving parameters for better evaluation of their performance and design. Among the conclusions, it was observed that increasing the compressive strength of masonry is not proportional to the increase of the grouting area and the efficiency of reinforcement to increase compressive strength is low. Stress-strain curves for the several materials combinations are made available.

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Pawliczek, Roland, and Tadeusz Lagoda. "Investigation of Changes in Fatigue Damage Caused by Mean Load under Block Loading Conditions." Materials 14, no. 11 (May 22, 2021): 2738. http://dx.doi.org/10.3390/ma14112738.

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The literature in the area of material fatigue indicates that the fatigue properties may change with the number of cycles. Researchers recommend taking this into account in fatigue life calculation algorithms. The results of simulation research presented in this paper relate to an algorithm for estimating the fatigue life of specimens subjected to block loading with a nonzero mean value. The problem of block loads using a novel calculation model is presented in this paper. The model takes into account the change in stress–strain curve parameters caused by mean strain. Simulation tests were performed for generated triangular waveforms of strains, where load blocks with changed mean strain values were applied. During the analysis, the degree of fatigue damage was compared. The results of calculations obtained for standard values of stress–strain parameters (for symmetric loads) and those determined, taking into account changes in the curve parameters, are compared and presented in this paper. It is shown that by neglecting the effect of the mean strain value on the K′ and n′ parameters and by considering only the parameters of the cyclic deformation curve for εm = 0 (symmetric loads), the ratio of the total degree of fatigue damage varies from 10% for εa = 0.2% to 3.5% for εa = 0.6%. The largest differences in the calculation for ratios of the partial degrees of fatigue damage were observed in relation to the reference case for the sequence of block n3, where εm = 0.4%. The simulation results show that higher mean strains change the properties of the material, and in such cases, it is necessary to take into account the influence of the mean value on the material response under block loads.

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Elbahy, Y. I., M. A. Youssef, and M. Nehdi. "Stress block parameters for concrete flexural members reinforced with superelastic shape memory alloys." Materials and Structures 42, no. 10 (November 27, 2008): 1335–51. http://dx.doi.org/10.1617/s11527-008-9453-z.

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18

Han, Quan Li, and H. J. Zhao. "Surface Strain and Roughness Change of Aluminum Block Ground by Fixed Abrasives." Key Engineering Materials 487 (July 2011): 131–34. http://dx.doi.org/10.4028/www.scientific.net/kem.487.131.

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This paper aims to investigate the machining characteristics of surface ground by fixed abrasives. Face grinding experiments of aluminum block are done. Different surface in experiment are generated through change of processing time while keeping other experiment parameters unchanged, and those tests of surface strain and roughness of aluminum blocks are conducted. The magnitude of stress and roughness on sample after experiment increases with processing time, which is also fit for the change of the above index parameter between before and after experiment. Larger surface stress of sample on which higher surface roughness is also seen is found in present investigation. The most helpful findings in experiments indict that engineering in workshops will get the method to achieve the product with high performance, when decreasing the surface stress and roughness and extending service life.

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Gao, Wenwei, Hairong Yang, Le Wang, and Ruilin Hu. "Numerical Simulations of the Soil–Rock Mixture Mechanical Properties Considering the Influence of Rock Block Proportions by PFC2D." Materials 14, no. 18 (September 20, 2021): 5442. http://dx.doi.org/10.3390/ma14185442.

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Soil-rock mixtures (S-RMs), as a kind of special engineering geological material, need to be studied because of the special structure and complex movement mechanism of their rock blocks, their physical and mechanical properties, and the factors underlying rock block movement in the process of their deformation and failure. In this paper, a series of discrete-element numerical models are constructed in particle flow code software (PFC2D). First, the random structure numerical models of S-RMs with different rock block proportions are established. Then, the parameters of the soil meso-structure are inversed by the biaxial simulation test, and a series of biaxial compressive tests are performed. The characteristics of stress and strain, deformation and failure, and rock block rotation and energy evolution are systematically investigated. The results show the following. (1) As the rock block proportion (confining pressure 0.5 MPa) increases, the peak strength of increases, the fluctuations of the post-peak become more obvious, and the dilatancy of the sample increases. (2) As the rock block proportion increases, the width of the shear band increases, the distribution of cracks becomes more complex and dispersed, and the range of the shear zone increases. (3) The number of rock blocks with rotation also increases significantly as rock block proportion increases, and the rotation angles are mostly between −5° and 5°. (4) The strain energy of S-RMs with different rock block proportions follows the same change rule as axial strain, showing a trend of first increasing and then decreasing, like the stress–strain curve.

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Berre, Toralv, Tom Lunne, Knut H. Andersen, Stein Strandvik, and Morten Sjursen. "Potential improvements of design parameters by taking block samples of soft marine Norwegian clays." Canadian Geotechnical Journal 44, no. 6 (June 1, 2007): 698–716. http://dx.doi.org/10.1139/t07-011.

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Undrained triaxial and direct simple shear tests on samples reconsolidated to the in situ effective stresses and oedometer tests have been carried out on standard piston tube and on high quality block samples from 12 deposits of soft Norwegian marine clays. Based on the results of a selected number of these tests, empirical procedures for estimating the effect of sample disturbance have been developed. These procedures can be used to show the potential increase that may be achieved in undrained shear strength and apparent preconsolidation stress by taking high quality block samples. Suggestions are also given regarding corrections for rate of loading and temperature effects; as well, examples are given regarding possible consequences for design if higher strengths are utilized.Key words: soft clays, sample disturbance, consolidation procedures, stress–strain–strength behaviour.

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Turuntaev, Sergey B., and Vasily Y. Riga. "Non-linear effects of pore pressure increase on seismic event generation in a multi-degree-of-freedom rate-and-state model of tectonic fault sliding." Nonlinear Processes in Geophysics 24, no. 2 (May 22, 2017): 215–25. http://dx.doi.org/10.5194/npg-24-215-2017.

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Abstract. The influence of fluid injection on tectonic fault sliding and seismic event generations was studied by a multi-degree-of-freedom rate-and-state friction model with a two-parametric friction law. A system of blocks (up to 25 blocks) elastically connected to each other and connected by elastic springs to a constant-velocity moving driver was considered. Variation of the pore pressure due to fluid injection led to variation of effective stress between the first block and the substrate. Initially the block system was in a steady-sliding state; then, its state was changed by the pore pressure increase. The influence of the model parameters (number of blocks, spring stiffness, velocity weakening parameter) on the seismicity variations was considered. Various slip patterns were obtained and analysed.

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Petermann, J., S. Hinz, and K. Schulte. "Degradation Parameters and Two-Stress Block Fatigue of Angle-Ply Carbon Fiber Reinforced Epoxy." Journal of ASTM International 1, no. 8 (2004): 19030. http://dx.doi.org/10.1520/jai19030.

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Liu, Guang Feng, Yang Lu, Ling Lu, and Jun Tao Wang. "Ultralow Permeability Reservoir Stress Field Simulation." Advanced Materials Research 816-817 (September 2013): 728–33. http://dx.doi.org/10.4028/www.scientific.net/amr.816-817.728.

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The simulation method of reservoir tectonic and present stress field was recommended, and in-situ stress distribution of C82 ultralow permeability reservoir formation in Changqing oilfied Z19 well block was computed. The method is based on finite element analysis, of which the contents and procedures include geological model establishment, calculation model establishment and results analysis. The simulation precision depends on the reliability of models. Inversion criteria need to be set to determine whether the ultimate simulating result is reasonable. Main inversion criteria include absolute inversion, principle stress criteria, deformation criteria, etc. The maximum principle stress value of C82 formation in Z19 well block is between 35.7 and 45.2MPa, whose direction is NE 72o-80o, and the dominant direction is NE 75o. The differential stress value is between 0.4 and 9.8MPa. The relationship between stress, reservoir parameters and production data was discussed. The simulation results can be taken as reference for well pattern design, optimization and overall fracturing design.

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Huang, Chi Kong, Chau Chen Torng, and Hsien Ming Chang. "Stress Analysis on the Stretch Forming of the Aluminum Saddle-Shaped Skins." Advanced Materials Research 89-91 (January 2010): 703–8. http://dx.doi.org/10.4028/www.scientific.net/amr.89-91.703.

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The stretch forming applied force during the forming process and exceed the yield stress of the raw material to make the part deforming plastically, and fitting the contour of a form block, then the purpose of forming can be reasonably achieved. The saddle-shaped skin located in the mating area between the vertical stabilizer and the empennage. This study investigates the stress distribution on the stretch forming of saddle-shaped skins. First, apply the FEM software-ABAQUS to analyses the stretch forming of saddle-shaped skin. Then use the statistical method to analysis the stress in different forming conditions. Finally, the stress of saddle-shaped skins on the critical location is analyzed and discussed. This study aims to modify the process parameters in advance to prevent the failure and defects of skin and provide valuable information for both production engineer and tool designer to improve their design of process parameters and form block.

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Зарецкая, Марина Валерьевна. "To the study of the natural seismic tension of geological massifs." Вестник Чувашского государственного педагогического университета им. И.Я. Яковлева. Серия: Механика предельного состояния, no. 4(46) (December 30, 2020): 124–30. http://dx.doi.org/10.37972/chgpu.2020.46.4.009.

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Методом блочного элемента проведено исследование блочной структуры, моделирующей геологический массив. Состояние геологической среды описывается уравнениями движениями для однородной, изотропной упругой среды в форме Ляме. Выписаны функциональные и псевдодифференциальные уравнения, получены интегральные представления блочного элемента. Установлены основные тенденции изменения контактных напряжений в зависимости от значений механических характеристик материала блоков и геометрических параметров структуры. The block structure method is used to study the block structure modeling a geological massif. The state of the geological medium is described by equations of motion for a homogeneous, isotropic elastic medium in the form of a Lame. Functional and pseudo-differential equations are written out, and integral representations of the block element are obtained. The main tendencies of contact stress variation are established depending on the values of the mechanical characteristics of the material of the blocks and the geometric parameters of the structure.

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Hadhood, Abdeldayem, Hamdy M. Mohamed, and Brahim Benmokrane. "Assessing Stress-Block Parameters in Designing Circular High-Strength Concrete Members Reinforced with FRP Bars." Journal of Structural Engineering 144, no. 10 (October 2018): 04018182. http://dx.doi.org/10.1061/(asce)st.1943-541x.0002173.

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Miao, Hong, Dun Wen Zuo, Hong Feng Wang, and X. W. Sha. "Effect of Optimization of Shot Peening Parameters on Surface Integrity of NAK80." Key Engineering Materials 426-427 (January 2010): 537–39. http://dx.doi.org/10.4028/www.scientific.net/kem.426-427.537.

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Shot peening is known to improve the fatigue performance of materials. The improvement in fatigue is that plastic deformation in the surface increases hardness, yield stress and microstrain of thinning Crystal block and dislocation density, and formed advantaged compress residual stress that are introduced into the near-surface of the components and which hinder crack initiation and growth. But over peening effect is produced when shot peening strengthening goes beyond a certain limit, which was adverse to improve surface quality. This paper adopted the optimization of the critical peening parameters to avoid appearing over peening effect. The experimental result showed that arc high value of optimal shot peening was 0.40mm.

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Zhou, Ji Jun, Huai Fu, Yue Zhang, Yan Li, and De Zhang. "Strength Attenuation and Post Failure Behaviour of Fine Sandstone." Advanced Materials Research 446-449 (January 2012): 3538–43. http://dx.doi.org/10.4028/www.scientific.net/amr.446-449.3538.

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Three types of physical tests were designed to study post failure behaviour and strength attenuation of fine sandstone. Tests include rock compression test, rock unloading test and rock block shear test. The stress-strain curves at different confining pressures had been obtained as well as axial strain-lateral strain curves. The differences of axial strain-lateral strain curves exhibit that stress peak point and the point of fault formation are apparently different for the rock. After the fault is generated, fractured rock slides on the fault surfaces, while confining pressure, material strength and structure effect decide the post failure behaviour. Damaged rock specimens were poured in concrete specimens as well as irregular blocks. Material strength of rock blocks was attained. Shear strength gradually attenuates with unloading points close to the peak. Past the stress peak, rock blocks from fractured rock still have considerable material strength. It is shown that there are differences of strength parameters obtained from direct shear test and triaxial test.

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Velayutham, Nedumaran, Selvaraju ., and Shanmugavelu . "Bilateral superficial cervical plexus block combined with general anaesthesia for thyroid surgery-a comparative study of intraoperative haemodynamic status and safety." International Journal of Research in Medical Sciences 6, no. 1 (December 23, 2017): 236. http://dx.doi.org/10.18203/2320-6012.ijrms20175726.

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Background: When general anaesthesia is employed for a surgery, the hemodynamic changes are intense during intubation, intraoperative stress and extubation. Hence, in the present study, by employing Bilateral Superficial Cervical Plexus Block using 0.5% Bupivacaine prior to skin incision, assessment of hemodynamic effects during intraoperative period is done. The aim of the study was to compare the intra operative hemodynamic status and the safety of bilateral superficial cervical plexus block with general anesthesia in thyroid surgerie.Methods: Bilateral superficial cervical plexus block was performed in patients undergoing simple thyroid surgery using normal saline in 29 control group patients and 0.5% Bupivacaine in 29 study group patients. Intraoperative hemodynamic status was monitored in both the groups using parameters such as heart rate, systolic blood pressure, diastolic blood pressure and mean blood pressure.Results: Hemodynamic parameters are not altered during the intraoperative period in the study and control group.Conclusions: Bilateral Superficial Cervical Plexus Block with bupivacaine did not alter the intraoperative hemodynamic parameters.

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Sarkar, Debashish, Andrey Bakulin, and Robert L. Kranz. "Anisotropic inversion of seismic data for stressed media: Theory and a physical modeling study on Berea Sandstone." GEOPHYSICS 68, no. 2 (March 2003): 690–704. http://dx.doi.org/10.1190/1.1567240.

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Nonhydrostatic stress, an often‐ignored source of seismic anisotropy, is universally present in the subsurface and may be as common as intrinsic or fracture‐induced anisotropy. Nonhydrostatic stress, applied to an initially transversely isotropic solid with vertical symmetry axis (VTI), results in an effective medium having almost orthorhombic symmetry (provided that one of the principal stresses is aligned with the symmetry axis). The symmetry planes observed in this orthorhombic medium are aligned with the orientations of the principal stresses, and anisotropic parameters (ε(1,2), δ(1,2,3), and γ(1,2)) can reveal information about the stress magnitudes. Thus, time‐lapse monitoring of changes in anisotropy potentially can provide information on temporal variations in the stress field. We use nonlinear elasticity theory to relate the anisotropic parameters to the magnitudes of the principal stresses and verify these relationships in a physical modeling study. Under the assumption of weak background and stress‐induced anisotropy, each effective anisotropic parameter reduces to the sum of the corresponding Thomsen parameter for the unstressed VTI background and the corresponding parameter associated with the nonhydrostatic stress. The stress‐related anisotropic parameters depend only on the differences between the magnitudes of principal stresses; therefore, principal stresses can influence anisotropic parameters only if their magnitudes differ in the symmetry plane in which the anisotropic parameters are defined. We test these predictions on a physical modeling data set acquired on a block of Berea Sandstone exhibiting intrinsic VTI anisotropy. Uniaxial stress, applied normal to the VTI symmetry axis, i.e., horizontally, produces an effective medium that is close to orthorhombic. We use two different methods to estimate the anisotropic parameters and study their variation as a function of stress. The first method utilizes conventional measurements of transmission velocities along the principal axes of the sample. The second method uses PP and PS reflection data acquired along seven different azimuths on the surface of the block. In accordance with theoretical predictions, the anisotropic parameters in the vertical plane normal to the stress are almost insensitive to the magnitude of the stress. In contrast, anisotropic parameters in the vertical plane of the applied stress increase approximately in a linear fashion with increasing stress. Except for the parameter δ(1), comparison of the measured values of anisotropic parameters with theoretical predictions shows satisfactory agreement. Despite some documented discrepancies, we believe that nonlinear elasticity may provide a suitable framework for estimating pore pressure and 3D stresses from seismic data.

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Dolwichai, T., J. Limtragool, and S. Bureerat. "Optimization of a Triangular Slot Shape in a Tire Tread Block by Using the Finite Element Analysis and MPSO." Advanced Materials Research 505 (April 2012): 424–28. http://dx.doi.org/10.4028/www.scientific.net/amr.505.424.

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The work of this paper presents the use of MPSO which is an evolutionary optimizer. The work objective is finding the optimal shape of triangular slot in a tire tread block. The numbers of design parameters with triangular slot are 9. They are used to characterize size and position of the triangular slot in a tire tread block. The optimization methods are implemented to solve two objectives. First, the normal contact stress at contact patch region must be lowest and second, the friction contact stress at the same region must be highest. Therefore, the problem type is bi-objective optimization. The finite element analyses are simulated by modeling of tire tread block contacting to the friction surface with commercial finite element program (ANSYS). The models are simulated as compressing and sliding or braking situation. The tire tread block is modeled as hyperelastic material which used the three basic tests, i.e., uni-axial tensile test, planar shear test and equal bi-axial tensile test. The best fitted of hyperelastic material model for the work is Ogden Hyper Foam order 3th. The results of work are present as the mean of design parameters which are accepted for two objectives.

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Zhang, Li Gang, Wei Ren, Yun Tao Wang, and Qiing Chai. "Analysis of Perforation Parameters under Fluid-Solid Coupling Theory." Advanced Materials Research 524-527 (May 2012): 1344–49. http://dx.doi.org/10.4028/www.scientific.net/amr.524-527.1344.

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In this paper, The use of the basic mechanics model, based on the use of fluid-structure coupling of thinking, the use of finite element software simulations, And Then quantitative study the effect of perforation parameters such as perforating depth, aperture,shooting density,shot phasing,drawdown on hole stability and well yield,make sure the weight size relationship of each perforation parameters about hole stability and well yield based on the orthogonal analysis. In the end based on the actual lithology information and original crustal stress distribution in longxi area of Daqing ,to design optimum perforating parameter of this block well.

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Hsu, Chaur‐Jian, and Michael Schoenberg. "Elastic waves through a simulated fractured medium." GEOPHYSICS 58, no. 7 (July 1993): 964–77. http://dx.doi.org/10.1190/1.1443487.

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Ultrasonic velocities were measured on a block composed of lucite plates with roughened surfaces pressed together with a static normal stress to simulate a fractured medium. The measurements, normal, parallel, and oblique to the fractures, show that for wavelengths much larger than the thickness of an individual plate, the block can be modeled as a particular type of transversely isotropic (TI) medium that depends on four parameters. This TI medium behavior is the same as that of an isotropic solid in which are embedded a set of parallel linear slip interfaces, specified by (1) the excess compliance tangential to the interfaces and (2) the excess compliance normal to the interfaces. At all static stress levels, we inverted the data for the background isotropic medium parameters and the excess compliances. The background parameters obtained were basically independent of stress level and agreed well with the bulk properties of the lucite. The excess compliances decreased with increasing static closing stress, implying that increasing static stress forces asperities on either side of a fracture into greater contact, gradually eliminating the excess compliance that gives rise to the anisotropy. A medium with such planes of excess compliance has been shown, theoretically, to describe the behavior of a medium with long parallel joints, as well as a medium with embedded parallel microcracks.

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Kumar, Prabhat. "Effect of strain ratio variation on equivalent stress block parameters for normal weight high strength concrete." Computers and Concrete 3, no. 1 (February 25, 2006): 17–28. http://dx.doi.org/10.12989/cac.2006.3.1.017.

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Yuan, Fang, and Yu-Fei Wu. "Analytical method for derivation of stress block parameters for flexural design of FRP reinforced concrete members." Composite Structures 229 (December 2019): 111459. http://dx.doi.org/10.1016/j.compstruct.2019.111459.

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Sonnov, M. A., A. V. Trofimov, A. E. Rumyantsev, and S. V. Shpilev. "Application of Numerical and Block Geomechanical Modelling to Determine Parameters of Large-Section Chambers." Mining Industry Journal (Gornay Promishlennost), no. 2/2021 (May 10, 2021): 127–31. http://dx.doi.org/10.30686/1609-9192-2021-2-127-131.

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The study is exemplified by complex workings of a main ore pass that include a variety of underground structures, usually with unique dimensions which depend on the function and size of the equipment placed. The technical solutions for the underground crushing plant and associated structures envisage construction of chambers with the height of up to 35 m and the width of up to 20 m at the depths exceeding 800-1000 m. Such conditions call for a closer attention to be paid to the mine support parameters, especially the bolting depth. A block geomechanical model was designed in the Micromine Mining Software for the rock mass of the new main ore pass. Geotechnical boreholes logs and results of physical and mechanical rock tests were used as the input data for the model. Four domains were identified in the block geomechanical model for subsequent numerical modelling. A 3D model of the stress-and-strain state of the rock mass was made using the CAE Fidesys software based on the Micromine wire-frame model of the main ore pass. The history of the rock mass incremental loading was reconstructed for correct simulation of its stress-and-strain state. Prior to the excavation, the rock mass is pre-stressed by the weight of the rock strata. The excavation phase was then simulated in the stepwise manner. An array of points with the values of maximum principal stresses was downloaded from the numerical model post-processing program and interpolated into the block geomechanical model to refine the SRF parameter of the Barton's Q rating. Based on the obtained Q values, the mine support parameters for chambers were determined using the Barton, Hutchinson and Potvin empirical methods.

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Ayub, Tehmina, Sadaqat Ullah Khan, and Nasir Shafiq. "Flexural Modelling and Finite Element Analysis of FRC Beams Reinforced with PVA and Basalt Fibres and Their Validation." Advances in Civil Engineering 2018 (2018): 1–18. http://dx.doi.org/10.1155/2018/8060852.

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A flexural capacity model for fibre-reinforced concrete (FRC) beams reinforced with PVA and basalt fibres is suggested for the rectangular beam sections. The proposed models are based on the concept of equivalent stress block parameters for both compressive and tensile stresses, similar to Eurocode and ACI code. The parameters are defined by allowing the conversion of the stress-strain models into equivalent rectangular stress blocks, similar to Eurocode 2. The flexural model is suggested to determine the loading capacity of 21 FRC beams containing up to 3% volume fraction of PVA and basalt fibres without reinforcing bars. In order to investigate the accuracy of the proposed flexure models, finite element analysis (FEA) of the same beams was carried out using the compressive and tensile stress-strain curves. Furthermore, 21 FRC beams subjected to three-point bending were tested. The results of the flexural models showed good agreement with the load-carrying capacity of the tested FRC beams, and the results of FEA of all beams showed a good correlation with the experimental results in terms of the maximum load, load versus midspan deflection patterns, and the maximum tensile strains.

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Sagaram, Madhulika, and Leonardo Lombardini. "Screening Pecan Cultivars for Drought Tolerance Using Physiological Parameters." HortScience 40, no. 4 (July 2005): 1129D—1129. http://dx.doi.org/10.21273/hortsci.40.4.1129d.

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Pecan is a riparian species distributed over an area of geographic and climatic variation; such a wide distribution produces exposure to varied environmental conditions, providing a potential for genetic adaptation within the cultivars. Genotypes can be screened in order to obtain more drought tolerant cultivars using indirect screening parameters (chlorophyll fluorescence, osmotic adjustment, and abscisic acid assay) based on physiological responses of plants to abiotic stress conditions. A study was established at Texas A&M University, College Station, using a mixture of fritted clay (Quick dry) and pure sand in 1:1 (by weight) ratio to study the effects of drought on pecan rootstocks. The experiment was set up with the three water potential levels as treatments (–0.033 MPa, –0.1 MPa, –0.3 MPa) in a randomized complete-block design with three blocks. Measurements will include leaf water relations (relative water content, leaf water potential, osmotic adjustments, etc.), gas exchange parameters [net carbon dioxide assimilation rate (A), transpiration rate (E), stomatal conductance (gs)], chlorophyll fluorescence measurements [minimum (Fo), maximum (Fm), and variable fluorescence (Fv), quantum efficiency], water use efficiency, and abscisic acid assay on roots. Statistical analysis systems (SAS) package will be used for analysis. PROC GLM of the SAS will be used for statistical analysis of study involving plant response to water potential levels.

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Zhao, Hong-Bao. "Experimental Study on Properties of Methane Diffusion of Coal Block under Triaxial Compressive Stress." Scientific World Journal 2014 (2014): 1–6. http://dx.doi.org/10.1155/2014/385039.

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Taking the standard size coal block samples defined by ISRM as research objects, both properties of methane diffusion of coal block under triaxial compressive stress and characteristic influences caused by methane pressure were systematically studied with thermo-fluid-solid coupling with triaxial servocontrolled seepage equipment of methane-containing coal. The result shows the methane diffusion property of coal block under triaxial compressive stress was shown in four-stage as follow, first is sharply reduce stage, second is hyperbolic reduce stage, third is close to a fixed value stage, fourth stage is 0. There is a special point making the reduced rate of characteristic curve of methane diffusion speed become sharply small; the influences of shape of methane diffusion speed characteristic curve caused by methane pressure are not obvious, which only is shown in numerical size of methane diffusion speed. Test time was extended required by appear of the special point makes the reduce rate of methane diffusion speed become sharply small. The fitting four-phase relation of methane diffusion of coal block under triaxial compressive stress was obtained, and the idea is proposed that influences of the fitting four-phase relation caused by methane pressure were only shown in value of fitting parameters.

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Tian, Yong, and Hai Lin. "Application of Rock Mechanics Parameters to Obtain Formation Pressure." Applied Mechanics and Materials 239-240 (December 2012): 803–6. http://dx.doi.org/10.4028/www.scientific.net/amm.239-240.803.

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Using triaxial tests of rock mechanics on stress testing instrument to analyze the results of its parameters, and obstained the the region that was consistent with the transformation between static and dynamic rock mechanics, the relationship between formation pore pressure and rock mechanical parameters, the pressure profile in the basis of rock mechanics parameters, etc. Combination of logging information and data, the method was identified which was in line with the use of rock mechanics parameters to strike a formation pressure. Using this method, I have analysised the formation pressure profiles of several wells in a block, and established the corresponding formation pressure detection section and the section of rock mechanics. The tested pressure and the measured pressure were compared more than 85% accuracy.

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Mousavian, Elham, and Claudia Casapulla. "Structurally informed design of interlocking block assemblages using limit analysis." Journal of Computational Design and Engineering 7, no. 4 (April 16, 2020): 448–68. http://dx.doi.org/10.1093/jcde/qwaa038.

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Abstract This paper presents a computational framework to design assemblages of interlocking blocks and to analyze their structural feasibility. The core of this framework is an extension of limit analysis to corrugated interfaces with orthotropic sliding behavior. Such block interfaces are made of a number of locks (i.e. projections on the corrugated faces, locking the blocks together) with rectangular cross section. The sliding resistance at the block interfaces is governed by the shear resistance of the locks and Coulomb’s friction law, normal to and along the locks, respectively. This resistance is assumed as a function of different interface geometric parameters and the stress state on an interface is represented by using a number of contact points distributed over the lock centerlines. The abstraction model has been validated through the comparison of the torsion–shear behavior of an interface obtained by the proposed model and experimental tests reported in the literature. The extended limit analysis has been implemented to model single-layer shells. When the model is infeasible, the geometry of the overall shell, blocks, and interlocking interfaces can be adjusted by the designer to make the model structurally feasible. The performance of the framework is presented through several examples, which demonstrate the relationships between the geometry of the interlocking interfaces and the stability of the assemblages.

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Zeng, Zhi Ping, Xue Song Wang, and Wen Rong Chen. "Study on Fatigue Characteristic of Double Block Ballastless Track under Coupling Loads." Advanced Materials Research 422 (December 2011): 789–93. http://dx.doi.org/10.4028/www.scientific.net/amr.422.789.

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Regarding double block ballastless track as research subject, three mechanical models were established, which include steel bar and concrete interaction mechanical model, spatial finite element static model of double block ballastless track, train-double block ballastless track vertical coupling dynamics model. According to concrete and steel bar stress time-dependant curves under axial even temperature and shrinkage load, temperature grads load and train load, fatigue load spectrum under coupling loads was obtained by using rain-flow counting method. Based on steel bar and concrete S-N curve, and Palmgren-Miner linear fatigue damage accumulation rule, track concrete layer fatigue life predicting model of double block ballastless track was established. Taking Changsha climatic condition for an example, the fatigue life of double block ballastless track is predicted, and the effects of design parameters to fatigue life are analyzed.

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Silva, Maria Liliane Dos Santos, Humberto Gildo de Sousa, Maria Lílian Dos Santos Silva, Claudivan Feitosa de Lacerda, and Enéas Gomes-Filho. "Growth and photosynthetic parameters of saccharine sorghum plants subjected to salinity." Acta Scientiarum. Agronomy 41, no. 1 (March 13, 2019): 42607. http://dx.doi.org/10.4025/actasciagron.v41i1.42607.

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Plants are often exposed to abiotic stresses such as salinity, which represents a barrier to the cultivation of agricultural species mainly in arid and semi-arid regions. This study evaluated the development of four saccharine sorghum genotypes for tolerance to different salinity levels under greenhouse conditions. The experimental design was a randomized complete block arranged in a 5 × 4 factorial scheme, which corresponded to five levels of irrigation water salinity [electrical conductivities of 0.5 (control), 2.5, 5.0, 7.5, and 10.0 dS m-1] and four saccharine sorghum genotypes (CSF 11, CSF 15, P 76 and P 298), with five replicates. The plants were evaluated for dry mass production, leaf area, height, stalk diameter, leaf gas exchange and relative chlorophyll content. The growth and leaf gas exchange measurements of the saccharine sorghum plants were significantly affected by salinity stress. Among the genotypes, CSF 11 and CSF 15 exhibited smaller reductions in growth, whereas P 298 showed the greatest reduction. These findings show that genotype CSF 11 can be classified as the most tolerant to salt stress, and genotype P 298 is the most sensitive.

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Huang, Rui, Zhaowei Chen, Fengshou Zhang, Xiaojin Zhou, Qian Wang, Hu Cao, Haozhe Zhang, and Xuegang Yang. "Fault Slip Risk Assessment and Treating Parameter Optimization for Casing Deformation Prevention: A Case Study in the Sichuan Basin." Geofluids 2020 (December 1, 2020): 1–17. http://dx.doi.org/10.1155/2020/8894514.

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Casing deformation is a key issue that restricts the efficient development of shale gas in the Sichuan Basin, southwest China. In this study, we take the Ning209 block as an example to analyze the characteristics of casing deformation distribution and the mitigation effect of using reduced treating parameters on casing deformation. The geological structure and in-situ stress characteristics of this block indicate that the high horizontal stress difference and high pore pressure may be the main cause of casing deformation. Hence, based on the fault likelihood and 3D in-situ stress model, a geomechanical probability model of fault slip is established to identify the areas with high risk of faults to explain the distribution of casing deformation and investigate the impact of reducing pumping rate on fault slip. The results show that the faults in the upper region of the block have a higher slip probability than the faults in the lower region, consistent with field casing deformation observation. The high stress difference and high pore pressure are the main factors causing a high slip probability of faults. After reducing pumping rate, slip probability is found to change from medium risk to low risk for faults in the lower region, which led to a significant reduction of casing deformation in the lower region. Reducing pumping rate can play a significant role in mitigating casing deformation caused by medium-risk faults, which has been proved by the field practices. This paper proposes a comprehensive method for preventing casing deformation by combining the fault slip risk assessment with the treating parameters optimization, which bridges the gap between prediction and control for mitigating casing deformation in the field.

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Silva, André A. R. da, Geovani S. de Lima, Carlos A. V. de Azevedo, Luana L. de S. A. Veloso, Hans R. Gheyi, and Lauriane A. dos A. Soares. "Salt stress and exogenous application of hydrogen peroxide on photosynthetic parameters of soursop." Revista Brasileira de Engenharia Agrícola e Ambiental 23, no. 4 (April 2019): 257–63. http://dx.doi.org/10.1590/1807-1929/agriambi.v23n4p257-263.

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ABSTRACT This study aimed to evaluate the gas exchanges and photosynthetic pigments of soursop seedlings cv. ‘Morada Nova’ irrigated with saline waters and subjected to exogenous application of hydrogen peroxide by seed soaking and foliar spraying. The study was carried out using plastic bags under greenhouse conditions at the Center of Technology and Natural Resources of the Federal University of Campina Grande, PB, Brazil, using a eutrophic Regolithic Neosol of sandy loam texture. Treatments were arranged in a randomized block design, in 5 x 5 factorial scheme, which consisted of five levels of electrical conductivity – ECw (0.7; 1.4; 2.1; 2.8 and 3.5 dS m-1) of irrigation water and five concentrations of hydrogen peroxide - H2O2 (0, 25, 50, 75 and 100 µM), with four replicates and three plants per plot. As the salt stress increased, there were reductions in internal CO2 concentration, instantaneous carboxylation efficiency and water use efficiency, and instantaneous carboxylation efficiency was the most sensitive variable. Hydrogen peroxide at concentrations of 25 and 50 µM attenuated the deleterious effects of water salinity on stomatal conductance, CO2 assimilation rate and chlorophyll a content, and the concentration of 25 µM was the most efficient. The content of chlorophyll b and carotenoids of soursop cv. ‘Morada Nova’ had the deleterious effects caused by the salinity of irrigation water mitigated by the exogenous application of hydrogen peroxide in the concentration of 25 μM.

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Verissimo, Mario Alvaro Aloisio, Ricardo Augusto de Oliveira, Sérgio Delmar dos Anjos e. Silva, Edelclaiton Daros, and Adílson Härter. "Genetic parameters and performance of sugarcane families under cold stress in the South of Brazil." Pesquisa Agropecuária Brasileira 53, no. 5 (May 2018): 583–92. http://dx.doi.org/10.1590/s0100-204x2018000500007.

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Abstract: The objective of this work was to estimate the genetic parameters for the performance prediction of sugarcane (Saccharum spp.) families under natural cold stress, in Southern Brazil, and to identify the best combinations of parents aiming at the selection for tolerance to cold. Fifty-three full-sib families were evaluated in an incomplete block design, with five replicates per family, in the municipality of Pelotas, in the state of Rio Grande do Sul, Brazil. Harvest occurred in August 2013, nine months after planting and after cold spells with negative temperatures down to -2.2ºC. Statistical analyses, performed with the mixed model methodology, detected significant differences among families. Heritability estimates among progeny means were higher than those of individual heritability. Estimates of genetic progress for the traits megagrams of stalks per hectare, megagrams of brix per hectare, and number of stalks indicated gains of 93.8, 91.0, and 53.3%, respectively. A set of eight promising families that combine high estimates for yield and cold stress tolerance was obtained.

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Suchánek, Andrej, Jozef Harušinec, Mária Loulová, and Peter Strážovec. "Analysis of the distribution of temperature fields in the braked railway wheel." MATEC Web of Conferences 157 (2018): 02048. http://dx.doi.org/10.1051/matecconf/201815702048.

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The article deals with detection of reduced stress in a braked railway wheel, based on thermal transient analysis on virtual models, which influence the characteristics of the railway wheels. Structural analysis was performed by means of the ANSYS Multiphysics program system package. Thermal transient analysis deals with detection of temperature fields which are a result of braking by brake block. The applied heat flux represents the heat generated by friction of brake block. It is applied to a quarter model of the wheel to speed up the calculation. This analysis simulates two braking processes with subsequent cooling. Distribution of the equivalent stress was detected in the railway wheel cross section, at selected points. The input parameters were taken from the thermal transient analysis. These equivalent stresses result from thermal load.

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Yussupov, Khalidilla, Saifilmalik Myrzakhmetov, Khairulla Aben, Serhii Nehrii, and Tetiana Nehrii. "Optimization of the drilling-and-blasting process to improve fragmentation by creating of a preliminary stress in a block." E3S Web of Conferences 280 (2021): 08015. http://dx.doi.org/10.1051/e3sconf/202128008015.

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At mining and processing complexes, many parameters today are evaluated from the point of view of the total process from geology to the final product. Changes in certain mining parameters inevitable lead to the changes in the following downstream processes. In this article, the focus is on the ore fragmentation, which is one of the most important parameters in many mines as it affects the downstream ore preparation and processing efficiencies, productivities and costs. In most of the cases, the cheapest way to improve the fragmentation of the ore is by changing the drilling-and-blasting design parameters. It of course increases the mining costs, but at the same time decreases the costs of the following processes, which are normally significantly higher. Therefore, authors of this article propose a new way of optimization of the drilling-and-blasting process by introducing new blast design modifications. Based on the analysis, research of the scientific information and the mining practise, the authors discuss the way of creation of the preliminary stress in the block of the open pit and hence improving fragmentation. Physical experimental blasts in “Belaya Gorka” open pit were performed and shown positive results reflecting a potential for continuation of the research in this direction in the future.

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Ahmed, B., AS Mitu, M. Sultana, N. Tasnim, and AHMMR Talukder. "Yield and Physiological Indices of Lentil Genotypes Against Drought Stress." Bangladesh Agronomy Journal 23, no. 2 (March 15, 2021): 97–102. http://dx.doi.org/10.3329/baj.v23i2.52457.

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Four lentil genotypes/varieties BLX-010014-9, ILI-5143, BARI Mosur-3 and BARI Mosur-2 were given irrigation regimes (with and without irrigation) to evaluate the physiological indices of genotypes against drought stress. The experiment was conducted during rabi (winter) season of 2017-18 under pot culture at the Plant Physiology Division of Bangladesh Agricultural Research Institute (BARI). The experimental design was randomized completed block (RCBD) with six replications. Irrespective of genotypes/varieties, physiological parameters as well as seed yield were greatly affected due to irrigation regimes. Based on physiological parameters like accumulation of chlorophyll, enzymatic and non-enzymatic antioxidantthe genotype BLX-010014-9 was found to be drought tolerant due to its higher and lower values of enzymatic and non-enzymatic antioxidant indices (greater CAT, POD, APX and lower MDA) across the irrigation levels treatment. This genotype may be further explored to characterize its genes and mechanisms against drought stress for increased lentil production and way to developing the drought tolerant variety/varieties. Bangladesh Agron. J. 2020, 23(2): 97-102

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Vasichkina, E. S., T. K. Kruchina, D. S. Lebedev, and D. F. Egorov. "Hypervagotonic binodal dysfunction in children. Features of the natural course." Kazan medical journal 96, no. 4 (August 15, 2015): 609–15. http://dx.doi.org/10.17750/kmj2015-609.

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Aim. To evaluate the clinical and electrophysiological picture of binodal disease in children, as well as studying the clinical course of this disease. Methods. To study the clinical and electrophysiological picture of autonomic binodal disease, 426 patients under 18 years old were examined; the average age was 15.35±2.43 years (3-17.9). Patient’s complaints, medical history were examined, ECG, 24-hour ECG, stress ECG (treadmill or bicycle test), echocardiography, transesophageal electrophysiologic study were performed. In the case of a combination with pathological signs of sinus node dysfunction and atrioventricular node conduction disorders with the normalization of all parameters after the atropine administration, hypervagotonic binodal dysfunction was diagnosed. To assess the clinical course of the disease, a group of 72 children was selected, who were monitored repeatedly. Mean follow-up duration was 33 months. Results. During the study period, sinus node dysfunction and atrioventricular blocks completely resolved in 14 (19.44%), seen as normal clinical picture with no complaints, normal heart rate, no signs of sinoatrial block or atrioventricular block, normalization of Wenckebach point position. Another 35 (48.62%) had only one node dysfunction resolved (either sinoatrial or atrioventricular - Wenckebach point position within the age normal values and/or atrioventricular block resolved). In 23 (31.94%) - deterioration of the sinus node and atrioventricular node dysfunction was observed. Conclusion. There are significant differences in the frequency characteristics of heart rhythm and electrophysiological parameters of sinus node function in children with a favorable clinical course of binodal disease and progressive course of the disease.

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Journal articles on the topic 'Stress block parameters'

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