Journal articles on the topic 'Compression effect'
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1
Ma, Wei Hua, and Hong Zhen Kang. "Experimental Study on Compressive Behavior of CFRP Confined Concrete Columns." Advanced Materials Research 446-449 (January 2012): 3725–29. http://dx.doi.org/10.4028/www.scientific.net/amr.446-449.3725.
Abstract:
Compressive tests of 30 concrete column specimens with three concrete strength grades are carried out in this paper to study ultimate compressive strength of specimens. The specimens are divided into three groups, that is, unconfined, confined by CFRP with no initial compression and confined by CFRP with various initial compressions. The different initial compressions’ influence on ultimate stresses and strains are investigated. The decrease of CFRP reinforcing effect due to pre-compression are analyzed. The research results provide experimental datum for reinforced design of existing concrete columns.
2
Lee, Jae-Min, and Hyeong-Wan Yun. "Effect of Chest Compression Position Depending on the Rescuer’s Hip Joint Angle During Basic CPR." Fire Science and Engineering 34, no. 2 (April 30, 2020): 103–9. http://dx.doi.org/10.7731/kifse.0902eaff.
Abstract:
This study aims to investigate the improvement in basic CPR quality on the basis of the hip joint angle of the rescuer among students in the Department of Emergency Medical Technology who completed a basic CPR curriculum. In this study, we carried out a comparative analysis using SimPad SkillReporter and Resusci Anne® QCPR® to measure the quality of CPR (depth of chest compressions, full relaxation, compression speed, and more) on the basis of the rescuer’s hip joint angle in accordance with the 2015 AHA Guidelines and conducted chest compressions and CPR 5 times in a 30:2 ratio. It was found that maintenance of the rescuer’s hip joint angle at 90 degrees while compressing and relaxing the chest made a statistically significant difference in both the experimental and control groups. Moreover, this indicated that the closer the hip joint angle was to 90 degrees, the better was the quality of basic CPR. However, there was no significant difference in the hip joint angle, degree of CPR, depth of chest compressions, chest compression speed, chest compression and relaxation percentages (%), accuracy of chest compressions, hands-off time during CPR, and percentage of chest compression time (p > 0.05). Maintaining the hip joint angle at 90 degrees for basic CPR was not significantly different from not maintaining this angle. Nonetheless, good results have been obtained at moderate depth and 100% recoil. Therefore, good outcome and high-quality CPR are expected.
3
Liu, Chunlei, Qun Zheng, Qi Wang, Aqiang Lin, Yuting Jiang, and Mingcong Luo. "Sensitivity Analysis of Multistage Compressor Characteristics Under the Spray Atomization Effect Using a CFD Model." Energies 12, no. 2 (January 18, 2019): 301. http://dx.doi.org/10.3390/en12020301.
Abstract:
In this paper, a CFD model is used to simulate the effect of spray atomization at the compressor inlet on a multistage axial subsonic compressor. Special attention is paid to the change of compressor characteristics with wet compression under different rotating speeds to gain the compressor characteristic lines of wet compression. The effects of pneumatic crushing and blade-wall-collision on water droplets and droplet trajectories are contrasted and analyzed under different spray conditions. Then, the whole/stage-by-stage compressor performances and the flow field are also investigated under dry and wet cases near the design operating condition. The results indicate that multistage compressor performance can be improved with wet compression under the proper water spaying rate and a small droplet size. The influence of pneumatic crushing on the water droplets below 20 μm can be ignored, and the effect of blade collision on water droplets above 5μm should be considered in the wet compression conditions. Compared to the dry compression, as measured by volume flow, wet compression with proper spaying conditions makes the front stages operate within a relatively high flow range and the back stages operate within a relatively low flow range. Additionally, the operating state with wet compression is opposite to the compressor operating near the surge boundary, which presents the phenomenon of “former surged and back blocking”.
4
Lee, Sang Eon, and Jung-Wuk Hong. "Effect of Crack Closure on Magnitude of Modulated Wave." International Journal of Structural Stability and Dynamics 20, no. 13 (December 2020): 2041018. http://dx.doi.org/10.1142/s0219455420410187.
Abstract:
Fatigue cracks generated by repeated loads cause structural failures. Such cracks grow continuously and at an increasing speed owing to the concentration of stresses near the crack tips. Therefore, the early detection of fatigue cracks is imperative in the field of structural-health monitoring for the safety of structures exposed to dynamic loading. In particular, the detection of those cracks subjected to compression is known as a challenging problem in the nondestructive inspection area. The nonlinear ultrasonic modulation technique is effective for the detection of microcracks smaller than the size of a wavelength because this technique uses the deformation of waves passing through the crack surfaces. However, the technique has not been thoroughly verified for detecting cracks subjected to external forces. In this study, nonlinear ultrasonic modulation tests are performed on two types of crack specimens under compressive forces. The results show that in fatigue-cracked specimens, the cracks can be detected using modulated waves even under strong compressions. With artificial cracks, buckling occurs at a relatively low compression, and the amounts of modulated waves rapidly increase due to the bending of the specimen before buckling failure takes place. In this study, the crack detection methodology under compression is proposed and experimentally verified. The proposed method might be beneficial to find cracks under compression in various structural components.
5
Shi, Feng Jian, Si Zhen Ye, Lei Gang Wang, and Sheng Lu. "Effect of Friction on Billet Deformation during Multi-Axial Compressions." Advanced Materials Research 143-144 (October 2010): 879–83. http://dx.doi.org/10.4028/www.scientific.net/amr.143-144.879.
Abstract:
The effect of friction on compression load, effective strain, damage value and maximum principal stress were analyzed by rigid-plastic finite element method during multi-axial compressions (MAC). The results show that with the number of compressions, the maximum compression load increases gradually, the effective strain distributes ringwise and the maximum effective strain is in the center and the minimum at the surface. The damage is inclined to appear at the barreled shape perpendicular to the longitudinal axis. With the increase of friction coefficient, the maximum compression load, strain inhomogeneity, damage value and maximum principal stress increase under the condition of same number of compression. These results indicate that the friction is adverse during MAC. Appropriate measures should be adopted to decrease the effect of frictional force.
6
Du, Haijun, Yanhua Ma, Ruoyan Li, Ting Lei, and Pei Wu. "Effect of vibrational frequency on alfalfa opening compression process." BioResources 17, no. 4 (October 14, 2022): 6706–17. http://dx.doi.org/10.15376/biores.17.4.6706-6717.
Abstract:
To reveal the action mechanism of vibration frequency in alfalfa opening compression, a self-developed vibration compression test system was used to evaluate the variation of compression force during alfalfa open compression. A faster vibration frequency yielded a smaller compression force required for compressing alfalfa into blocks. Compared with free vibration compression, vibration compression was beneficial to release the internal stress of alfalfa block, reduce the forming pressure, and stabilize the high density. In the range of test vibration frequency, when the frequency was 15 Hz, the residual internal stress release ratio of alfalfa block was the highest, and the stable density of alfalfa block was the largest. Considering the pressure and alfalfa block density comprehensively, the optimized vibration frequency was approximately 15 Hz.
7
HAN, FENGXIA, QING LIU, XIN GUO, MENG ZHANG, and XIA HAN. "ANALYTICAL STUDY ON AXIAL AND ECCENTRIC COMPRESSIVE BEHAVIOR OF POPLAR COLUMN STRENGTHENED BY BFRP." WOOD RESEARCH 67(1) 2022 67, no. 1 (January 16, 2022): 11–25. http://dx.doi.org/10.37763/wr.1336-4561/67.1.1125.
Abstract:
In this work, the compression behaviour of the Xinjiang poplar column was reinforced by basalt fibre reinforced polymer (BFRP) strips with different reinforced configurations, and thenumerical simulations were performed on the axial and eccentric compressions of poplar columns unreinforced and reinforced with BFRP to assess the effect of the bearing capacity and deformation of the columns. The results show that the use of BFRP to reinforce the Xinjiang poplar column effectively improves its axial compressive bearing capacity (axial compression) andbending bearing capacity (eccentric compression), and at the same time, the bearing capacity and stiffness of the columns strengthened by BFRP increased with the bonding area of BFRP.
8
He, Jun Yan, Wan Jie Meng, and Chu Jun Zhao. "Effects of Core Diameter Variation on the Silicon Photonic Nanowire Soliton Effect Compressor." Advanced Materials Research 571 (September 2012): 395–99. http://dx.doi.org/10.4028/www.scientific.net/amr.571.395.
Abstract:
The influences of core diameter variation on silicon photonic nanowire soliton-effect femtosecond pulse compressor at 1550 nm have been numerically analyzed. It is shown that when the core diameter smaller than 355 nm, the compression factor increases and the quality factor and the optimum fiber length decreases with the increasing core diameter; when the core diameter larger than 355 nm, the core diameter has little effect on the optimum fiber length, but the compression factor decreases and the quality factor increases with the increasing core diameter.
9
Sha, Yu, Hui Tang, Xin Song, and Jia Zhen Zhang. "Finite Element Analysis of the Effect of the Compressive Loading on Fatigue Crack Growth under Different Loading." Applied Mechanics and Materials 16-19 (October 2009): 269–72. http://dx.doi.org/10.4028/www.scientific.net/amm.16-19.269.
Abstract:
In this paper, elastic-plastic finite element analysis has been performed in order to obtain the fatigue crack tip parameters under tension-compression loading. Two centre-cracked high-strength aluminum alloy with a crack length of 2mm under different tension-compression loading are analyzed. The analysis shows that the compressive loading has a significant contribution towards the crack tip plasticity and the crack tip stress. In a tension-compression loading the crack tip displacement increases with the increase of the compressive stress and the crack tip compress stress increases with the increase of the compressive stress. The maximum stress intensity Kmax in the tension part of the stress cycle and the maximum compressive stress in the compression part of the stress cycle are the main factors controlling the near crack tip parameters.
10
Jee, Yong Ju, and Stephen R. Swanson. "Effect of State of Stress on Compression Failure in Carbon/Epoxy Laminates." Journal of Engineering Materials and Technology 117, no. 3 (July 1, 1995): 347–50. http://dx.doi.org/10.1115/1.2804550.
Abstract:
Compression loadings in thick composites can in some cases lead to three-dimensional states of stress with a compressive mean stress. A model is developed in the present work that attempts to incorporate this compressive mean stress into a prediction for compression strength of carbon/epoxy fiber composites. The model assumes that the fibers have an initial misalignment, and that composite failure occurs when the fiber-matrix bond strength is exceeded. Literature values for the effect of pressure on bond strength are included. Comparisons with experimental data support the predicted increase in compression strength with pressure.
11
Feng, Yan Feng, Tian Hong Yang, Hua Wei, Hua Guo Gao, and Zhe Zhang. "Research of Inclination Angle Effect on Joint Rock Macromechanical Parameters." Materials Science Forum 704-705 (December 2011): 1089–94. http://dx.doi.org/10.4028/www.scientific.net/msf.704-705.1089.
Abstract:
The joint of rock mass influences and controls the rock mass intensity, deformation characteristics and instability failure in the rock engineering to a great extent. Using the similar material simulation is of different inclination angle of non-penetration jointing and non-jointing rock mass, through using rigid servo compression machine to carry uniaxial compression test, we get a nearly same trend of joint rock mass stress-strain curve of different angle, the curve of inclination angle of 45 is analyzed, the test result shows that the compressive strength first decreases and then increases gradually with the increase of rock inclination angle. The compression intensity is its minimum when of the inclination angle of 45°, and the deformation modulus first decreases and then increases, but deformation modulus of 30° is its minimum. In addition, through the use of developed RFPA2D system to simulate on trial uniaxial compression value based on microscopic damage mechanics, we get the conclusion that the numerical analysis and test result is fitting approximately, it is validated that the numerical model can simulate joint rock well. Keywords: joint rock mass, inclination angle, uniaxial compression, compressive intensity, deformation modulus
12
Sun, Jianting, Xin Zhou, Qi Liang, Zhitao Zuo, and Haisheng Chen. "The Effect of Wet Compression on a Centrifugal Compressor for a Compressed Air Energy Storage System." Energies 12, no. 5 (March 8, 2019): 906. http://dx.doi.org/10.3390/en12050906.
Abstract:
There is an urgent demand to reduce compression power consumption in Compressed Air Energy Storage (CAES) systems. Wet compression has been widely used in gas turbines to reduce compressor power consumption and improve thermal efficiency, but this technology has not been applied yet in the CAES field. In this paper, a centrifugal compressor for CAES was numerically studied to investigate the effect of wet compression on compressor and droplet motion. The results showed that wet compression makes the performance curve shift to a high-pressure ratio/efficiency. Meanwhile, wet compression lowers the stall margin and narrows the stable operation range, and the effect is enhanced with the increase of water injection ratio or the decrease of average droplet diameter. Wet compression can effectively save compressor power consumption during energy storage, and at the designed pressure ratio, the power consumption can be reduced by 1.47% with a water injection ratio of 3% and an average droplet diameter of 5 μm. Influenced by the inertia and secondary flow, the droplets migrate to the impeller pressure and shroud side, thus causing brake loss by impacting on blades. The migration of droplets strengthens with the increase in the average droplet diameter and flow coefficient.
13
Kang, Hyun-Su, Sung-Yeon Kim, and Youn-Jea Kim. "Wet Compression Study for an Aero-Thermodynamic Performance Analysis of a Centrifugal Compressor at Design and Off-Design Points." Processes 10, no. 5 (May 9, 2022): 936. http://dx.doi.org/10.3390/pr10050936.
Abstract:
In this study, to analyze the effect of wet compression technology on the aero-thermodynamic performance of a centrifugal compressor, a numerical analysis study was conducted on the design point and off-design point. Wet compression technology sprays water droplets at the inlet of the compressor. During the compression process, water droplets evaporate, reducing the heat of compression and reducing the compression work, which improves the efficiency of the compressor. In wet compression technology, detailed research is needed for the application to compressors because the droplet behavior affects the internal flow. The main parameters for wet compression technology are the droplet size and injection rate selection, and the flow inside the compressor changed by the droplet behavior was analyzed. When the droplet size and injection rate were changed at the design point and the off-design point, it was confirmed that a small droplet size was effective in both areas, and it was confirmed that the performance improved as the flow rate increased. The internal flow changed greatly depending on the size of the droplet. As a result, the centrifugal compressor to which the wet compression technology was applied had a lower outlet temperature than dry compression at both the design point and the off-design point and had increases in the pressure ratio and efficiency. However, the surge margin decreased by about 2% in the surge region. The reason is that due to high-speed rotation, particles move in the outer diameter direction and are driven into a tip-leakage flow, and many stagnant flows occur without flowing into the main flow. Through the study results, it was possible to understand the effects of wet compression technology on the performance and efficiency increase of centrifugal compressors and the effects of particle behavior on the internal flow of the compressor at the off-design point.
14
Hayati, Anis Kamilah, and Haris Suka Dyatmika. "THE EFFECT OF JPEG2000 COMPRESSION ON REMOTE SENSING DATA OF DIFFERENT SPATIAL RESOLUTIONS." International Journal of Remote Sensing and Earth Sciences (IJReSES) 14, no. 2 (January 8, 2018): 111. http://dx.doi.org/10.30536/j.ijreses.2017.v14.a2724.
Abstract:
The huge size of remote sensing data implies the information technology infrastructure to store, manage, deliver and process the data itself. To compensate these disadvantages, compressing technique is a possible solution. JPEG2000 compression provide lossless and lossy compression with scalability for lossy compression. As the ratio of lossy compression getshigher, the size of the file reduced but the information loss increased. This paper tries to investigate the JPEG2000 compression effect on remote sensing data of different spatial resolution. Three set of data (Landsat 8, SPOT 6 and Pleiades) processed with five different level of JPEG2000 compression. Each set of data then cropped at a certain area and analyzed using unsupervised classification. To estimate the accuracy, this paper utilized the Mean Square Error (MSE) and the Kappa coefficient agreement. The study shows that compressed scenes using lossless compression have no difference with uncompressed scenes. Furthermore, compressed scenes using lossy compression with the compression ratioless than 1:10 have no significant difference with uncompressed data with Kappa coefficient higher than 0.8.
15
AKYOL, Burak, Mustafa GÜDEN, and Subhan NAMAZOV. "EXPERIMENTAL INVESTIGATION OF THE EFFECT OF STRAIN RATE ON THE CRUSHING STRENGTH OF A CELLULAR CONCRETE." Machine Science Journal 1, no. 1 (May 15, 2023): 4–21. http://dx.doi.org/10.61413/ftxi2310.
Abstract:
The strain rate dependent compressive strength of an autoclaved aerated concrete (AAC) having a density of 600 kg m-3 was experimentally investigated between quasi-static and high strain rates (2x10-3-~4150 s-1) through quasi-static and dynamic compression, confined compression and indentation tests. High strain rate equilibrium and direct impact non-equilibrium compression tests in conjunction with the high strain rate confined compression and indentation tests were conducted in a compression Split Hopkinson Pressure Bar. The experimental results showed two different regions of the compressive strength-dependency on the strain rate: a low-strain rate-dependent region from quasi-static to ~18 s-1 and a high-strain ratedependent region from ~18 s-1 to ~1000 s-1. The switch of the failure mode from the single axial cracking at quasi-static strain rates to the extensive axial and circumferential cracking at increasing strain rates was ascribed to both the axial and radial inertia. The dynamic increased factor (DIF=dynamic strength/static strength) showed an abrupt increase after ~18 s-1 as similar with the compressive strength. The mean confined and indentation strength values also increased as the velocity increased, while the mean confined compression strength values were shown to be comparable with the dynamic compressive strength values. The inertia and strain rate contributions to the enhancement of DIF until about 1000 s-1 were predicted by taking the quasistatic indentation strength as the full confinement strength.
16
Wang, Xiao Hong, Qiao Gang Hu, Shi Yu Zhong, Teng Dang, Hai Lun Wang, and Yuan Hua Lin. "Effect of Nickel-Modified SiC Particles on Compressive Damage of SiCp / 7075 Composites." Materials Science Forum 944 (January 2019): 705–13. http://dx.doi.org/10.4028/www.scientific.net/msf.944.705.
Abstract:
The wettability between silicon carbide and aluminum is poor, silicon carbide is difficult to fuse or the distribution of silicon carbide is not uniform in the ingot when the SiCp / 7075 composite is prepared by melt casting.The surface modification of SiCp by nickel plating can significantly reduce the wetting angle of SiC/Al and improve the distribution uniformity of silicon carbide in SiCp / 7075. In this thesis, the thermal compression process 6.5% SiCp / 7075 reinforced by nickel-plated modified silicon carbide is simulated by DEFOEM-3D software.The influence of the shape and particle size of nickel-plated modified silicon carbide on its compressive damage has been highlighted, and the deformation characteristics of the SiC/Ni/Al interface layer in the thermal compression process have been discussed. The numerical simulation results show that the 6.5% SiCp / 7075 reinforced by spherical nickel-plated modified silicon carbide particles with a particle size of 15 μm has the smallest compression damage value of 0.0426, at this point the compression temperature is 400°C, the compression ratio is 15, and the compression rate is 0.03s-1. the hot compression test of 6.5% SiCp / 7075 reinforced by spherical nickel-plated modified silicon carbide particles with a particle size of 15 μm was performed by using the same compression parameters as the numerical simulation. After hot pressing, the sample had a smooth surface with few obvious cracks, which was consistent with the numerical simulation results. Key words: nickel-plating modification; silicon carbide particles; compressive damage; grain size; grain morphology
17
Tu, Ruichen, Ning Wei, Yongmao Pei, Yan Liu, Fengguo Zhang, and Dongsheng Zhang. "The Effect of Compression on the Void Coalescence under Strong Dynamic Loading." Advances in Materials Science and Engineering 2022 (February 28, 2022): 1–11. http://dx.doi.org/10.1155/2022/9990161.
Abstract:
The void coalescence under strong dynamic loading is a significant spallation process for ductile metals. Since the spallation is basically dominated by tension waves, most void coalescence studies have focused on the tension effect. However, it is known that in spallation, the material initially undergoes a strong compression wave, and then an irreversible deformation is produced by the compression wave inside the material. Therefore, in this paper, the effect of compression on the void coalescence is investigated using the molecular dynamics (MD) simulation. It was found that as the compressive strain increases, the yield strength decreases first and then increases. The results showed that due to the Bauschinger effect (BE), the yield strength decreases by 19.43% from 5.66 GPa without compressive loading to 4.56 GPa when the compressive strain is −7.5%, after which the yield strength increases. The voids do not coalesce when the compressive strain is −8%. In addition, it was found that during the compressive phase, the void surfaces would generate dislocations, which could obstruct the void coalescence in the tensile phase. Furthermore, under compressive loading, the temperature effect on the void coalescence was studied, and it was found that lower temperatures could suppress the void coalescence.
18
Aswath, P. B., S. Suresh, D. K. Holm, and A. F. Blom. "Load Interaction Effects on Compression Fatigue Crack Growth in Ductile Solids." Journal of Engineering Materials and Technology 110, no. 3 (July 1, 1988): 278–85. http://dx.doi.org/10.1115/1.3226049.
Abstract:
The influence of the very first compression cycle on subsequent Mode I crack growth in notched plates of ductile solids subject to fully compressive cyclic loads has been examined in this work. Whereas stable crack growth occurs from the root of the notch over hundreds of thousands of compression cycles, the amplitude of the very first compression cycle is found to have a decisive effect on the total distance of crack advance. Specifically, a three-fold increase in the stress amplitude during the first compression cycle alone leads to more than a ten-fold increase in the total distance of crack growth during subsequent cycles. Finite element calculations of the crack closure stress levels during cyclic compression are in concurrence with the experimental results of closure stresses (measured from changes in compliance) for a lower strength steel. A brief discussion is also presented of the effects of periodic compressive overloads on crack growth behavior under far-field cyclic compression.
19
Gindl, W. "Comparing Mechanical Properties of Normal and Compression Wood in Norway Spruce: The Role of Lignin in Compression Parallel to the Grain." Holzforschung 56, no. 4 (June 27, 2002): 395–401. http://dx.doi.org/10.1515/hf.2002.062.
Abstract:
Summary Cell-wall lignin content and composition, as well as microfibril angle of normal and compression wood samples were determined prior to mechanical testing in compression parallel to the grain. No effect of increased lignin content on the Young's modulus in compression wood was discernible because of the dominating influence of microfibril angle. In contrast, compressive strength of compression wood was not negatively affected by the high microfibril angle. It is proposed that the observed high lignification in compression wood increases the resistance of the cell walls to compression failure. An increased percentage of p-hydroxyphenylpropane units observed in compression wood lignin may also contribute to the comparably high compressive strength of compression wood.
20
Yu, W., and R. O. Ritchie. "Fatigue Crack Propagation in 2090 Aluminum-Lithium Alloy: Effect of Compression Overload Cycles." Journal of Engineering Materials and Technology 109, no. 1 (January 1, 1987): 81–85. http://dx.doi.org/10.1115/1.3225939.
Abstract:
Fatigue crack propagation behavior has been examined in a commercial 12.7 mm thick plate of Al-Cu-Li-Zr alloy, 2090, with specific emphasis on the effect of single compression overload cycles. Based on low load ratio experiments on cracks arrested at the fatigue threshold (ΔKTH), it is found that crack growth at ΔKTH can be promoted through the application of periodic compression cycles, of magnitude two times the peak tensile load. Similar to 2124 and 7150 aluminum alloys, such compression-induced crack growth at the threshold decelerates progressively until the crack re-arrests, consistent with the reduction and subsequent re-generation of crack closure. The compressive loads required to cause such behavior, however, are far smaller in the 2090 alloy. Such diminished resistance of aluminum-lithium alloys to compression cycles is discussed in terms their enhanced “extrinsic” crack growth resistance from crack path deflection and resultant crack closure, and the reduction in the closure from the compaction of fracture surface asperities by moderate compressive stresses.
21
Aji Suryadi, Yanuar, and Gunawan. "Compressor Piping Design Effect on Vibration Data." Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 88, no. 1 (October 11, 2021): 94–108. http://dx.doi.org/10.37934/arfmts.88.1.94108.
Abstract:
One of the systems for oil and gas production supports is the nitrogen compression system. Problem found that condition of the compressor has high vibration with the maximum overall the first compressor is 9,813 mm / s RMS, the second compressor is 7,439 mm / s RMS, the third compressor is 7,430 mm / s RMS, the fourth compressor is 13.47 mm / s RMS, the fifth compressor is 13,220 mm / s RMS, and sixth compressor already damaged. This research will discuss the nitrogen compression process in terms of the characteristics of the output fluid flow from the compressor using computational fluid dynamics. The first piping system shows that the standby compressor's flow has a higher pressure reaching 10.72 - 11.82 Pa but it is still acceptable. The second piping system with two compressors in operation shows that the pipeline flows in the opposite direction with high pressure. Flow turbulence occurs, resulting in a higher speed. The highest pressure in the pipeline reaches 44.79 Pa, mostly at the fifth and sixth compressors. The conclusion from this research there is high pressure backflow when one compressor stops and another compressor start running. Prevents direct pressure to the compressor or the condensed fluid from the gas flowing and entering the compressor used valve addition.
22
Yan, Yufu, Jiamin Zhao, Long Chen, Hongjian Zhao, Olga Klimova-Korsmik, Oleg V. Tolochko, Fuxing Yin, Puguang Ji, and Shaoming Kang. "Effect of Strain Rate on Compressive Properties of Aluminium-Graphene Composites." Metals 13, no. 3 (March 20, 2023): 618. http://dx.doi.org/10.3390/met13030618.
Abstract:
Graphene-reinforced aluminium composites have been widely studied due to their excellent mechanical properties. However, only a few studies have reported their dynamic compression properties. The purpose of this study is to investigate the quasi-static and dynamic compression properties of graphene-reinforced aluminium composites. The addition of graphene improved the compressive stress resistance and energy absorption capacity of the aluminium matrix. An aluminium-0.5 wt.% graphene composite exhibited good compressive properties due to the different interfacial wave impedance generated by the additional grain boundaries or Aluminium-Graphene interfaces.
23
Yu, Annie, Sachiko Sukigara, and Miwa Shirakihara. "Effect of Silicone Inlaid Materials on Reinforcing Compressive Strength of Weft-Knitted Spacer Fabric for Cushioning Applications." Polymers 13, no. 21 (October 22, 2021): 3645. http://dx.doi.org/10.3390/polym13213645.
Abstract:
Spacer fabrics are commonly used as cushioning materials. They can be reinforced by using a knitting method to inlay materials into the connective layer which reinforces the structure of the fabric. The compression properties of three samples that were fabricated by inlaying three different types of silicone-based elastic tubes and one sample without inlaid material have been investigated. The mechanical properties of the elastic tubes were evaluated and their relationship to the compression properties of the inlaid spacer fabrics was analysed. The compression behaviour of the spacer fabrics at an initial compressive strain of 10% is not affected by the presence of the inlaid tubes. The Young’s modulus of the inlaid tubes shows a correlation with fabric compression. Amongst the inlaid fabric samples, the spacer fabric inlaid with highly elastic silicone foam tubes can absorb more compression energy, while that inlaid with silicone tubes of higher tensile strength has higher compressive stiffness.
24
Schümann, Kerstin, Olga Sahmel, Heiner Martin, Klaus-Peter Schmitz, and Niels Grabow. "Investigation of Bauschinger effect in thermo-plastic polymers for biodegradable stents." Current Directions in Biomedical Engineering 3, no. 2 (September 7, 2017): 623–25. http://dx.doi.org/10.1515/cdbme-2017-0130.
Abstract:
AbstractThe Bauschinger effect is a phenomenon metals show as a result of plastic deformation. After a primary plastic deformation the yield strength in the opposite loading direction decreases. The aim of this study is to investigate if there is a phenomenon similar to Bauschinger effect in thermoplastic polymers for stent application that would influence the mechanical properties of these biodegradable implants. Combined uniaxial tensile with subsequent compression tests as well as conventional compression tests without prior tensile loading were performed using biodegradable polymers for stent application (PLLA and a PLLA based blend). Comparing the results of compression tests with prior tensile loading to the compression-only tests a decrease in compressive strength can be observed for both of the tested materials. The conclusion of the performed experiments is that there is a phenomenon similar to Bauschinger effect not only in metallic materials but also in the examined thermoplastic polymers. The observed reduction of compressive strength as a consequence of prior tensile loading can influence the mechanical behaviour, e.g. the radial strength, of polymeric stents after sustaining a complex load history due to crimping and expansion.
25
Wolfenden, A., and LJ Javorik. "Effect of Axial Compression." Journal of Testing and Evaluation 14, no. 4 (1986): 213. http://dx.doi.org/10.1520/jte11264j.
26
ARIFFIN, SITI HAJAR, KONSTANTINOS GKATZIONIS, and SERAFIM BAKALIS. "EFFECT OF COMPRESSION ON MECHANICAL PROPERTIES OF READY-TO-EAT (RTE) SPINACH VARIETIES." Malaysian Applied Biology 49, no. 3 (October 25, 2020): 107–15. http://dx.doi.org/10.55230/mabjournal.v49i3.1553.
Abstract:
Compression-induced injury is frequently encountered during handling, packaging, transporting, and storage. In this study, compression test was performed using a mechanical tester, Universal Testing Machine Z030 (Zwick/Roell, Germany). Spinach varieties (Teen, Organic, Salad, and Baby) were used to study the response of spinach varieties towards stress. For single loading/unloading compression, maximum work (MaxW) and area under the curve (AUC) required to compress Organic spinach were found to be the highest followed by Teen and Salad spinach. The MaxW and AUC were found to be decreasing after storage which showed that the total work generated to compress the leaves was reduced due to texture degradation of the product after storage. For multiple loading/unloading compression, as the number of compressions increased, the MaxW decreased. Similar trend was observed at day 6. Apart from that, the MaxW for all the three spinach types were found to be similar at the 5th compression. This shows that regardless of the spinach types, they reached maximum resistance towards stress after the 5th consecutive compression. Under 200 N compression, leaves with stem required higher energy to compress compared to leaves without stem. However, for leaves compressed under 50 N and 100 N, the difference was only noticed on the 1st compression. The MaxW was found to be similar for leaves with stem and without stem starting from the 2nd compression till the 5th compression. The irregular and larger cell size of Organic spinach as compared to round-shaped and smaller cell size of Teen and Salad spinach may contribute to the ability of the Organic spinach tissue to have higher resistance towards mechanical stress during compression.
27
Clark, Michael D., Mikaela P. Davis, Meredith A. Petschauer, Erik E. Swartz, and Jason P. Mihalik. "Delivering Chest Compressions and Ventilations With and Without Men's Lacrosse Equipment." Journal of Athletic Training 53, no. 4 (April 1, 2018): 416–22. http://dx.doi.org/10.4085/1062-6050-91-17.
Abstract:
Context: Current management recommendations for equipment-laden athletes in sudden cardiac arrest regarding whether to remove protective sports equipment before delivering cardiopulmonary resuscitation are unclear. Objective: To determine the effect of men's lacrosse equipment on chest compression and ventilation quality on patient simulators. Design: Cross-sectional study. Setting: Controlled laboratory. Patients or Other Participants: Twenty-six licensed athletic trainers (18 women, 8 men; age = 25 ± 7 years; experience = 2.1 ± 1.6 years). Intervention(s): In a single 2-hour session, participants were block randomized to 3 equipment conditions for compressions and 6 conditions for ventilations on human patient simulators. Main Outcome Measure(s): Data for chest compressions (mean compression depth, compression rate, percentage of correctly released compressions, and percentage of optimal compressions) and ventilations (ventilation rate, mean ventilation volume, and percentage of ventilations delivering optimal volume) were analyzed within participants across equipment conditions. Results: Keeping the shoulder pads in place reduced mean compression depth (all P values < .001, effect size = 0.835) and lowered the percentages of both correctly released compressions (P = .02, effect size = 0.579) and optimal-depth compressions (all P values < .003, effect size = 0.900). For both the bag-valve and pocket masks, keeping the chinstrap in place reduced mean ventilation volume (all P values < .001, effect size = 1.323) and lowered the percentage of optimal-volume ventilations (all P values < .006, effect size = 1.038). Regardless of equipment, using a bag-valve versus a pocket mask increased the ventilation rate (all P values < .003, effect size = 0.575), the percentage of optimal ventilations (all P values < .002, effect size = 0.671), and the mean volume (P = .002, effect size = 0.598) across all equipment conditions. Conclusions: For a men's lacrosse athlete who requires cardiopulmonary resuscitation, the shoulder pads should be lifted or removed to deliver chest compressions. The facemask and chinstrap, or the entire helmet, should be removed to deliver ventilations, preferably with a bag-valve mask.
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Yao, Wang, Xi’an Li, Youjun Wu, Quan Xue, Zhitao Hao, Jianfeng Shi, Chen Zhang, and Yongbiao Ren. "Effect of Height-to-Diameter Ratio on the Compression Test Results of Remodeled Loess and Its Mechanism." Buildings 13, no. 1 (January 9, 2023): 176. http://dx.doi.org/10.3390/buildings13010176.
Abstract:
The confined compression test is the most widely used test to study the compressive deformation of soil in a laboratory, and the height–diameter (H/D) ratio has a significant effect on the confined compression test results. However, there has been limited research on the effect of the H/D ratio on loess compression deformation. In this work, a series of confined compression tests were carried out on the remolded loess samples using a modified oedometer to explore the effect of the H/D ratio on the compression deformation. Scanning electron microscopy (SEM) tests were used to investigate the variation of the microstructure in soils with different H/D ratios along the sample height. The results showed that the axial strain of the remolded loess decreases with the increase in the H/D ratio. The influence of the H/D ratio on the compression deformation is not obvious at lower pressures and compaction degrees, but it is significantly enhanced when the H/D ratio is beyond 0.65. The compression curves of the remolded loess samples with different H/D ratios fit the Gompertz equation well, and the transition point of the compression curves becomes difficult to identify with the increase in the H/D ratio. The compression index (Cc) decreases exponentially as a function of the H/D ratio, while the compressive yield stress (Pc) increases linearly with the increase in the H/D ratio. SEM analysis showed that, with the increase in the H/D ratio, the compression deformation of the sample changed from the whole sample involved in compression to the part of the soil in contact with the pressure. The compression of loess is mainly dominated by the compression of macropores and mesopores. The development of the soil–ring wall friction on the compression deformation induced by the H/D ratio was analyzed based on the change in microstructure, and a three-stage development of the soil–ring wall friction was established. These results and analysis established the connection between the specification and the literature, providing strong support for the rationality of the confined compression test results.
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Presley, Terrance, Evilia Kurnia, and Basia Wronski. "Case study of the effects on coal seam gas well production with installation of well head compression (oil-flooded rotary screw type): early outcomes of an Australian trial of four wells in the Bowen Basin." APPEA Journal 57, no. 2 (2017): 629. http://dx.doi.org/10.1071/aj16199.
Abstract:
This paper discusses the early outcomes of a trial of well head compression on coal seam gas (CSG) wells to lower surface pressure at the well head. This is a case study of four Johnson Controls Frick rotary screw compressor packages that were installed on CSG wells in an Origin Energy field in the Bowen basin and the early effects of lower well pressures on increased gas production due to the installation of compression. In mid-2016 Johnson Controls installed four compressor packages on Origin Energy wells with different characteristics (age, flow pressure), with a view of determining uplift of gas flow over the remaining life of the well, as well as operational issues with having well head compression. The expected versus actual uplift is compared for the different wells, with a view of providing some guidance on future potential wells that will benefit from this type of compression. Operational issues, such as effects on water flow, effect of oil and overall design considerations for well head compression, are also discussed.
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Fam, M. A., and M. B. Dusseault. "Effect of unloading duration on unconfined compressive strength." Canadian Geotechnical Journal 36, no. 1 (August 8, 1999): 166–72. http://dx.doi.org/10.1139/t98-074.
Abstract:
This note examines the effect of unloading duration on unconfined compression test results. Artificial clayey specimens were prepared using the slurry consolidation technique. Extracted specimens were loaded vertically under K0 conditions, and the load was kept constant until the end of primary consolidation. Specimens were unloaded and unconfined compression tests were carried out at different times after unloading. It is observed that the longer the unloading duration, the lower the measured unconfined strength. This behavior is attributed to the presence of negative excess pore pressure that dissipates with time, reducing the strength. Using the measured coefficient of consolidation, the degree of excess pore pressure dissipation and therefore the average mean effective stress near the failure zone can be calculated at the time of failure. Mohr circles are drawn tangential to the total shear envelope, using the calculated mean effective stresses. Reasonable agreement between predicted and measured unconfined compressive strengths has been observed, suggesting that consolidation theory can be adopted to assess the effect of unloading duration on unconfined compressive strength. Finally, engineering applications using a similar concept are briefly discussed.Key words: clays, unloading, consolidation, unconfined compression tests, triaxial tests.
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Qiu, Tian, and Lihong Liang. "Size effect on the compressive mechanical properties of pearl with “brick-mortar” structure." Journal of Physics: Conference Series 2519, no. 1 (June 1, 2023): 012027. http://dx.doi.org/10.1088/1742-6596/2519/1/012027.
Abstract:
Abstract The size dependence of four different diameters of pearls with “brick-mortar” structure was studied by uniaxial compression experiments. The results show that the failure of pearls with different diameters under the compressive load is not complete brittleness, but has a certain toughness. The maximum failure load and compressive strength of pearls cannot be considered as constants, which have a significant size dependence. The maximum failure load increases with the increase of pearl diameter, and the compressive strength decreases with the increase of pearl diameter. In addition, the compressive strength of pearls with different diameters conforms to the Weibull statistical law. When the compression fracture probability is 50%, the compressive strength of pearls with different diameters shows a significant size effect, and pearls with smaller diameters have greater compressive strength.
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Zamfirescu, Calin. "MODELING AND OPTIMIZATION OF AN AMMONIA-WATER COMPRESSION-RESORPTION HEAT PUMPS WITH WET COMPRESSION." Transactions of the Canadian Society for Mechanical Engineering 33, no. 1 (March 2009): 75–88. http://dx.doi.org/10.1139/tcsme-2009-0008.
Abstract:
Wet ammonia-water compression-resorption heat pumps constitute an attractive alternative to the commonly known heat pumps based on Osenbrück cycle because they eliminate the necessity of oil-liquid refrigerant separation. In this respect, a special designed oil-free compressor operating under wet (two-phase) conditions equips the heat pump. The compressor is lubricated by the liquid refrigerant which is carried-out while compressing the vapor. The thermodynamic cycle is located completely inside the two-phase region. In this paper are demonstrated two procedures to optimize the design for COP maximization. It is shown that there is: (i) an optimal choice of the vapor quality at suction, and (ii) an optimal distribution of heat transfer surface between the resorber and the desorber (the total amount of heat transfer surface, being an expression of investment cost, is fixed). The circulating concentration of ammonia has to be chosen such that the minimum pressure in the system is over one bar (to avoid air penetration from the atmosphere) and the maximum pressure is bounded by a technical-economical maximal limit. A general procedure for calculation of the optimal cycle parameters is presented and exemplified for a case with practical relevance. The paper presents only the trends and rough quantitative estimations because the analyzed case is restricted to the ideal isentropic compression. Further research is needed to quantify in detail the effect of compression irreversibility.
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Takey, A. S. M. Aziz Naser, G. M. Ismail Hossain, Soumik Sarker, and Md Arifuzzaman. "Effect of Nylon Fiber Reinforcement on Mechanical Behavior of Expanded Perlite/Sodium Silicate Composites." IOP Conference Series: Materials Science and Engineering 1305, no. 1 (April 1, 2024): 012033. http://dx.doi.org/10.1088/1757-899x/1305/1/012033.
Abstract:
Abstract In this research, expanded perlite/sodium silicate composites reinforced with nylon fibers were manufactured with varying percentages of nylon fibers without changing the quantity of expanded perlite and sodium silicate solution. The composites were made by compression molding and cured at a temperature of 120 degrees Celsius for 48 hours. The flexural and compression tests were conducted according to the ASTM standards in the universal testing machine. The maximum flexural and compressive properties are found for 1.62 percent nylon fiber reinforcement. The addition of a higher quantity of nylon fiber in the composites deteriorates the compressive and flexural properties. The energy absorption during flexural and compression tests is improved significantly due to nylon fiber reinforcement. The fiber-reinforced composites show the ability to carry a significant amount of load even after crack initiation.
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Wee, Jeremy CP, Mooppil Nandakumar, Yiong Huak Chan, Rowena SL Yeo, Kaldip Kaur, V. Anantharaman, Susan Yap, and Marcus EH Ong. "Effect of Using an Audiovisual CPR Feedback Device on Chest Compression Rate and Depth." Annals of the Academy of Medicine, Singapore 43, no. 1 (January 15, 2014): 33–38. http://dx.doi.org/10.47102/annals-acadmedsg.v43n1p33.
Abstract:
Introduction: The aim of the study is to investigate the effect of using Automated External Defibrillator (AED) audiovisual feedback on the quality of cardiopulmonary resuscitation (CPR) in a manikin training setting. Materials and Methods: Five cycles of 30 chest compressions were performed on a manikin without CPR prompts. After an interval of at least 5 minutes, the participants performed another 5 cycles with the use of real time audiovisual feedback via the ZOLL E-Series defibrillator. Performance data were obtained and analysed. Results: A total of 209 dialysis centre staff participated in the study. Using a feedback system resulted in a statistically significant improvement from 39.57% to 46.94% (P = 0.009) of the participants being within the target compression depth of 4 cm to 5 cm and a reduction in those below target from 16.45% to 11.05% (P= 0.004). The use of feedback also produced a significant improvement in achieving the target for rate of chest compression (90 to 110 compressions per minute) from 41.27% to 53.49%; (P <0.001). The mean depth of chest compressions was 4.85 cm (SD = 0.79) without audiovisual feedback and 4.91 (SD = 0.69) with feedback. For rate of chest compressions, it was 104.89 (SD = 13.74) vs 101.65 (SD = 10.21) respectively. The mean depth of chest compression was less in males than in females (4.61 cm vs 4.93 cm, P = 0.011), and this trend was reversed with the use of feedback. Conclusion: In conclusion, the use of feedback devices helps to improve the quality of CPR during training. However more studies involving cardiac arrest patients requiring CPR need to be done to determine if these devices improve survival. Key words: Cardiopulmonary resuscitation, Chest compression, Quality
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Narloch, Piotr, Piotr Woyciechowski, Jakub Kotowski, Ireneusz Gawriuczenkow, and Emilia Wójcik. "The Effect of Soil Mineral Composition on the Compressive Strength of Cement Stabilized Rammed Earth." Materials 13, no. 2 (January 10, 2020): 324. http://dx.doi.org/10.3390/ma13020324.
Abstract:
Cemented stabilized rammed earth (CSRE) is a building material used to build load bearing walls from locally available soil. The article analyzes the influence of soil mineral composition on CSRE compressive strength. Compression tests of CSRE samples of various mineral compositions, but the same particle size distribution, water content, and cement content were conducted. Based on the compression strength results and analyzed SEM images, it was observed that even small changes in the mineral composition significantly affected the CSRE compressive strength. From the comparison of CSRE compressive strength result sets, one can draw general qualitative conclusions that montmorillonite lowered the compressive strength the most; beidellite also lowered it, but to a lesser extent. Kaolinite lightly increased the compressive strength.
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Pattamaprom, Cattaleeya, Duangkamol Dechojarassri, and Worsak Kanok-Nukulchai. "The Effect of Cure Conditions on the Strength of Ebonite Rubber Network." Rubber Chemistry and Technology 78, no. 4 (September 1, 2005): 724–35. http://dx.doi.org/10.5254/1.3547909.
Abstract:
Abstract Although ebonite has been discovered for a long time, its applications were still limited to some household products. Recently, ebonite rubber has become of interest, especially for structural applications due to its high and adjustable strength and rigidity. The rigidity can be enhanced by several folds by utilizing appropriate curing conditions. In this study, we investigate the effect of curing conditions on the mechanical properties of ebonite at various cure time. Here, the crosslink densities were determined qualitatively both before and after compression cycles to investigate the change in crosslink networks. After the pre-molding stage, the curing process was either continued in the compression mold, in the air-oven, or under nitrogen atmosphere. For the compression-mold and nitrogen-atmosphere curing, crosslink densities and the compressive moduli increased significantly with cure time, whereas, for air-oven curing, only slight increases in the afro-mentioned properties were observed. After completing four compression cycles, the crosslink density and mechanical properties remain high only when curing was done in the compression mold. Therefore, curing under pressure as in the compression mold for a prolonged time could be a mean in boosting the mechanical properties of ebonite.
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Larhrib, H., J. I. Wells, and M. H. Rubinstein. "Compressing polyethylene glycols: The effect of compression pressure and speed." International Journal of Pharmaceutics 147, no. 2 (February 1997): 199–205. http://dx.doi.org/10.1016/s0378-5173(96)04818-1.
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Hindratmo, Dimas Bayu, Bagiyo Condro Purnomo, Akbar Satrio Wicaksono, and Ilham Habibi. "Komparasi Kinerja AC Kendaraan dengan Menggunakan Refrigeran R-134a, dan R-290." Borobudur Engineering Review 3, no. 1 (May 17, 2023): 1–11. http://dx.doi.org/10.31603/benr.8898.
Abstract:
The development of vapor compression refrigeration systems currently depends on the issue of environmental problems related to ozone layer depletion (ODP) and global warming potential (GWP). In addition to environmental issues, low energy use is also in the spotlight of researchers. To solve the problem of refrigeration development, natural refrigeration, especially hydrocarbons, is the focus of attention. Hydrocarbons are refrigerants that have excellent properties to be natural refrigerants. This study aims to compare the performance of refrigerant R-134a with R-290. The research used a standard vapor compression refrigeration system with a TEV-type expansion valve. The system performance is seen through compression, refrigeration effect, and COP with variations in compressor rotational speed of 1000 rpm, 1500 rpm, and 2000 rpm. The results showed that the compression work, refrigeration effect, and coefficient of performance (COP) of R-290 had a more excellent value. R-290 produces the highest compression work at a 2000 rpm compressor speed of 33.34 kJ/kg for the refrigeration effect at 1000 rpm of 353.33 kJ/kg and COP at 1500 rpm 12.32.
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Wang, Yong-jing, Dan Qian, Ya-qi Chen, Zhi-jia Zhang, and Zhong-xiao Song. "Effect of plate lattice-filling on the compressive mechanical property of 3D-printed square honeycombs." Journal of Sandwich Structures & Materials 24, no. 3 (January 23, 2022): 1580–96. http://dx.doi.org/10.1177/10996362211068053.
Abstract:
In this paper, a novel plate lattice-filled square honeycomb (PLSH) is proposed in an attempt to improve the quasi-static compression performance and energy absorption of structure. Firstly, the quasi-static compression performance of the 3D-printed PLSH was analyzed through experimental investigation and finite element analysis. The results showed that the compressive strength and energy absorption capacity of the proposed PLSHs are higher than the sum of those of square honeycomb (SH) and plate lattices (PLs) which were tested individually. It can be seen that compressive strength per unit mass [Formula: see text] and energy absorption per unit mass [Formula: see text] by 15%–45% and 51%–151% relative to the SH, respectively, and 65.2%–582% and 78%–196% relative to the PLs, respectively. The strengthening mechanism is that the mutual constraint between the SH and PL stabilizes the buckling and alters the compressive deformation mode of both constituents, resulting in elevating compression performance and energy absorption capability of the PLSH.
40
Yang, Shuai, and Wenbai Liu. "The Effect of Changing Fly Ash Content on the Modulus of Compression of Stabilized Soil." Materials 12, no. 18 (September 10, 2019): 2925. http://dx.doi.org/10.3390/ma12182925.
Abstract:
Adding a curing agent can enhance the mechanical properties of soil including its compressive strength. However, few studies have quantitatively analyzed the compressive strength and microstructure of soils to explore the impact of changes in the microstructure on compressive strength. In addition, the cost of curing agents is too high to be widely used. In this study, curing agents with different proportions of fly ash were added to dredger fill to reduce the amount of curing agents needed. The quantitative analysis of the relationships between the modulus of compression Es and microstructures of stabilized soil samples is presented. The modulus of compression Es was gauged from compression tests. Microscopic images acquired using a scanning electron microscope were processed using the Image-Pro Plus (IPP) image processing software. The microscopic parameters, obtained using IPP, included the average equivalent particle size Dp, the average equivalent aperture size Db, and the plane pore ratio e. This research demonstrated that the fly ash added to the curing agent achieved the same effect as the curing agent, and the amount of curing agent required was reduced. Therefore, the modulus of compression for stabilized soil can be improved. This is due to the hydration products (i.e., calcium silicate hydrate, calcium hydroxide, and ettringite), produced by the hydration reaction, and which adhere to the surface of the particles and fill the spaces among them. Thus, the change in the pore structure and the compactness of the particles helps to increase the modulus of compression. In addition, there was a good linear relationship between the modulus of compression and the microscopic parameters. Using the mathematical relationships between the macroscopic and microscopic parameters, correlations can be built for macro–microscopic research.
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Kovac, M. "Size effect of mortar specimens under uniaxial compression." IOP Conference Series: Materials Science and Engineering 1252, no. 1 (September 1, 2022): 012012. http://dx.doi.org/10.1088/1757-899x/1252/1/012012.
Abstract:
Abstract This paper investigates the phenomenon of the size effect of quasi-brittle lime-based material. This research aims to confirm the existence of a size effect on a homogeneous material - test specimens of mortar, which are subjected to uniaxial compression and provide additional knowledge to explain the causes of the size effect. This paper deals with the analysis of the results of experimental tests of mortar specimens without inclusion and with one centrally located steel inclusion. Two series of tests with different slenderness and size were prepared. The results of the experiment showed that the compressive strength of the test specimens decreased with increasing specimen size. The larger interface area between the inclusion and the mortar matrix negatively affected the compression strength.
42
Zhang, Wei, Xiaoyu Bai, Bowen Hou, Yadong Sun, and Xiao Han. "Mechanical properties of the three-dimensional compression-twist cellular structure." Journal of Reinforced Plastics and Composites 39, no. 7-8 (November 17, 2019): 260–77. http://dx.doi.org/10.1177/0731684419888588.
Abstract:
The cellular structure can exhibit many special mechanical behaviors due to its variable cell shape. A three-dimensional compression-twist cell structure based on the rotation mechanism of two-dimensional chiral cell structure is developed, which has twist deformation under axial compression. The shape of three-dimensional compression-twist cell structure is determined through cell angle, cell length, and thickness ratio. Analytical expressions of effective Young’s modulus, Poisson’s ratio, and twist angle are derived by using beam theory, which have a good agreement with the finite element calculations and the deformation process of the cell is discussed. To work on the effect of geometric parameters of cell on the mechanical properties, a finite element analysis model of compression-twist cell structure is carried out, which shows the process of elastic and plastic deformation under compression. Effects of cell angle, cell length, and thickness ratio are fully discussed, which indicate that cell angle has obvious nonlinear effect on relative twist angle and could stiffen it. Finally, a compression-twist cell structure sample is made through three-dimensional printing, and an in-plane compressive experiment is carried out to prove analytical and finite element analysis results.
43
Chen, Yanqin, Jinghui Zhao, Cuihong Jin, Yuchao Ke, Decai Li, and Zixi Wang. "Effect of Clamping Compression on the Mechanical Performance of a Carbon Paper Gas Diffusion Layer in Polymer Electrolyte Membrane Fuel Cells." Membranes 12, no. 7 (June 23, 2022): 645. http://dx.doi.org/10.3390/membranes12070645.
Abstract:
During all the assembly stages of a polymer electrolyte membrane fuel cell (PEMFC) stack, gas diffusion layers (GDLs) endure clamping loads in the through-plane direction several times. Under such complicated assembly conditions, GDLs have to deform with the changes in structure, surface roughness, pore size, etc. A comprehensive understanding of the compressive performance of GDLs at different clamping phases is crucial to the assembly process improvement of PEMFCs. Two typical clamping compression was designed and performed to get close to the actual assembly conditions of PEMFCs. The results indicate that the initial clamping compression and the magnitude of the maximum clamping load have great impacts on the segmented compressive properties of GDLs. The nonlinear compressive performance of the GDL is mainly attributed to the unique microstructural information. The rough surface morphology contributes to the initial compressive characteristics where the big strain along with the small stress occurs, and the irreversible failures such as carbon fiber breakages and adhesive failures between fibers and binders account for the hysteresis between different compression stages. Importantly, it is found that the clamping compression hardly influences the small pore distribution below 175 μm but affects the large pore distribution over 200 μm.
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Ahmad, Seleem, Esraa Ali, Mohamed Moawad, and Hesham Elemam. "Experimental and numerical investigation the effect of concrete strength and area of steel reinforcement on mechanical performance of functionally graded reinforced concrete beams." Frattura ed Integrità Strutturale 17, no. 65 (June 22, 2023): 270–88. http://dx.doi.org/10.3221/igf-esis.65.18.
Abstract:
In this work, an experimental and numerical program was designed to evaluate the role of compressive strength, Fc, and area of reinforcing steel, As, on the flexural behavior of functionally graded reinforced concrete beams. Eighteen layered sections of reinforced concrete beams were tested with different compressive strengths arrangement and area of main steel. The result showed that the minimum steel reinforcement with higher compressive strength in the compression zone increases load capacity and ductility. The average steel reinforcement with higher strength in the compression zone increases load capacity and decreases ductility. The results also approved that; higher strength in the compression zone can be used in beams with a high tensile steel ratio for decreasing compression steel as an economic side. 3D finite element was executed using ABAQUS to simulate experimental beams. The numerical result showed variation from the experimental but still, the behavior of numerical beams is the same as the experimental.
45
Rotman, Guy, Amir Feder, and Roi Reichart. "Model Compression for Domain Adaptation through Causal Effect Estimation." Transactions of the Association for Computational Linguistics 9 (2021): 1355–73. http://dx.doi.org/10.1162/tacl_a_00431.
Abstract:
Abstract Recent improvements in the predictive quality of natural language processing systems are often dependent on a substantial increase in the number of model parameters. This has led to various attempts of compressing such models, but existing methods have not considered the differences in the predictive power of various model components or in the generalizability of the compressed models. To understand the connection between model compression and out-of-distribution generalization, we define the task of compressing language representation models such that they perform best in a domain adaptation setting. We choose to address this problem from a causal perspective, attempting to estimate the average treatment effect (ATE) of a model component, such as a single layer, on the model’s predictions. Our proposed ATE-guided Model Compression scheme (AMoC), generates many model candidates, differing by the model components that were removed. Then, we select the best candidate through a stepwise regression model that utilizes the ATE to predict the expected performance on the target domain. AMoC outperforms strong baselines on dozens of domain pairs across three text classification and sequence tagging tasks.1
46
Du, Yubing, Zhiqing Zhao, Qiang Xiao, Feiting Shi, Jianming Yang, and Peiwei Gao. "Experimental Study on the Mechanical Properties and Compression Size Effect of Recycled Aggregate Concrete." Materials 14, no. 9 (April 29, 2021): 2323. http://dx.doi.org/10.3390/ma14092323.
Abstract:
To explore the basic mechanical properties and size effects of recycled aggregate concrete (RAC) with different substitution ratios of coarse recycled concrete aggregates (CRCAs) to replace natural coarse aggregates (NCA), the failure modes and mechanical parameters of RAC under different loading conditions including compression, splitting tensile resistance and direct shear were compared and analyzed. The conclusions drawn are as follows: the failure mechanisms of concrete with different substitution ratios of CRCAs are similar; with the increase in substitution ratio, the peak compressive stress and peak tensile stress of RAC decrease gradually, the splitting limit displacement decreases, and the splitting tensile modulus slightly increases; with the increase in the concrete cube’s side length, the peak compressive stress of RAC declines gradually, but the integrity after compression is gradually improved; and the increase in the substitution ratio of the recycled aggregate reduces the impact of the size effect on the peak compressive stress of RAC. Furthermore, an influence equation of the coupling effect of the substitution ratio and size effect on the peak compressive stress of RAC was quantitatively established. The research results are of great significance for the engineering application of RAC and the strength selection of RAC structure design.
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Özbek, Ö., Ö. Y. Bozkurt, and A. Erkliğ. "Effect of Basalt Intraply Fiber Hybridization on the Compression Behavior of Filament Wound Composite Pipes." International Polymer Processing 36, no. 2 (May 1, 2021): 193–204. http://dx.doi.org/10.1515/ipp-2020-4005.
Abstract:
Abstract The current study deals with the effect of basalt fiber hybridization on the compressive properties of composite pipes reinforced with glass fiber and carbon fiber. Hybrid and non-hybrid fiber reinforced pipes (FRPs) were fabricated through wet filament winding technique. Intraply fiber winding structure in which different fiber types were simultaneously wound at the layer was employed for the hybridization. The FRP samples wound by different fiber winding angles (± (40°), ± (55°), ± (70°)) were prepared in order to gain a better insight on the influence of basalt intraply fiber hybridization. The compression properties of FRP samples were experimentally determined by quasi-static compression tests using external parallel-plates for both the axial and radial directions. The non-hybrid carbon FRP pipes showed the maximum axial compression strength in parallel to the highest strength and lowest ductility of carbon fibers, while the minimum axial compression strength was obtained for the non-hybrid pipes reinforced with basalt fibers that, in comparison, exhibit much less strength and higher ductility. The pipes submitted to the axial compression tests predominantly failed due to the development of cracks and buckling along the fiber direction. While the inclusion of basalt fiber reduced the axial compression behavior of the non-hybrid carbon and glass FRP samples, it improved that behavior in the radial compression tests. Delamination was determined as the major failure mode for the damaged FRPs under radial compression. It is found that the incorporation of basalt fiber provides improvements in radial compression properties as opposed to axial compression properties and in the same manner the increment in fiber winding angle makes a positive contribution to radial compression properties.
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Tabbakh, Thamer, Abdulaziz Kurdi, and Animesh Kumar Basak. "Effect of Strain Rate and Extrinsic SIZE Effect on Micro-Mechanical Properties of Zr-Based Bulk Metallic Glass." Metals 11, no. 10 (October 11, 2021): 1611. http://dx.doi.org/10.3390/met11101611.
Abstract:
In this study, the mechanical properties and deformation features of Zr-based bulk metallic glass (BMG) are investigated at micro-scale via in situ micro-pillar compression. Furthermore, the effects of the strain rate and micro-pillar diameter on respective stress–strain curves are investigated. Together with the mechanical properties, such unique in situ micro-pillar compression techniques provide physical status to the micro-pillars, referring to the instances of stress–strain curves. It is noted that the effect of the strain rate on the stress–strain behaviour of the BMG diminishes with increasing micro-pillar diameter. In contrast, yield and ultimate compressive strength increase with increasing micro-pillar diameter, up to 4 µm. The deformation details after compression, as a result of conformed mechanical loading, are analysed by SEM and TEM. As evident from electron microscopy investigation, the plastic deformation is evidenced by the presence of multiple slip/shear bands, acting as load accommodation mechanisms in the course of mechanical loading together and resemble local plastic flow (ductile in nature) between two shear plans.
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Al-Quraishi, Hussein, Mahdi Al-Farttoosi, and Raad Abdulkhudhur. "Compression Splices of Reinforcing Bars in Reactive Powder Concrete." Civil Engineering Journal 5, no. 10 (October 21, 2019): 2221–32. http://dx.doi.org/10.28991/cej-2019-03091406.
Abstract:
Compression splices are widely used in compression members such as columns in multi- story buildings. There are efficient design equations for compression splice of reinforcement embedded in conventional concrete proposed by design codes of practice. However, there is no design equation for compression splice in compression members made of reactive powder concrete (RPC). So, it is required to introduce a design equation to calculate the steel bars lap splice length of RPC compression members. In this study, an experimental work was conducted to investigate the effect of different variables on compression splices strength. These variables were compressive strength of concrete, transverse reinforcement amount, splice length, yield stress of reinforcement and spliced rebar diameter. The experimental results showed that; Increase in the yield stress of reinforcing bars, length of spliced bars and compressive strength of concrete result in increasing in splice strength. Meanwhile, increase in diameter of reinforcing bars result in decreasing in compression splice strength. The increase in the amount of transverse reinforcement has insignificant effect on compression spliced strength of rebar. Finite element analysis was used to analyze the tested specimens and compared between numerical and experimental result was carried out. The numerical and experimental ultimate load and load-deflection behavior is very close to each other. Finite element method was used to investigate a wide range of experimental variables values through a parametric analysis. A new proposing equation for compression splicing of rebar in RPC column is presented in this research.
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Win, Htay. "Evaluation of Compression Lines and Aging Effect on Clayey Soils." International Journal of Trend in Scientific Research and Development Volume-2, Issue-5 (August 31, 2018): 2318–24. http://dx.doi.org/10.31142/ijtsrd18348.