Journal articles: 'Relative compaction'

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CARTER, M. R. "RELATIVE MEASURES OF SOIL BULK DENSITY TO CHARACTERIZE COMPACTION IN TILLAGE STUDIES ON FINE SANDY LOAMS." Canadian Journal of Soil Science 70, no. 3 (August 1, 1990): 425–33. http://dx.doi.org/10.4141/cjss90-042.

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Field studies concerned with soil physical properties require methods to quantify and characterize soil compaction, especially for tillage experiments. The bulk densities of a Charlottetown and Gowanbrae fine sandy loam were related to a maximum or standard compaction state for each soil to obtain a measure of relative compaction. The two soils were both classified as Orthic Humo-Ferric Podzols. Relative compaction was closely related to the volume of macropores (r2 = 0.85). Over a 3-yr period, mouldboard ploughing loosened the soil to give an average relative compaction of 77%. Subsequent soil consolidation and settling increased relative compaction to 84% over the growing season. Direct-drilling maintained relative compaction at a limited range of 88–91%. Relative grain yield of cereals was related (r2 = 0.69) using a polynomial curve to relative compaction. A range of 77–84% relative compaction was associated with a relative grain yield ≥ 95%. A relative compaction of 84–89% was considered the equilibrium soil density level for the two soils under study. This range was related to a macropore volume of 13.5–10% which is adequate for permeability but possibly inadequate for optimum soil aeration under a humid soil moisture regime. Overall, relative compaction provided a useful index or standard to assess changes in soil bulk density and proved to be a biologically meaningful soil physical parameter. Key words: Soil compaction indices, relative compaction, Podzolic soil, fine sandy loam, cereal yield

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Voicu, Gheorghe, Mircea Lazea, Gabriel-Alexandru Constantin, Elena-Madalina Stefan, and Mariana-Gabriela Munteanu. "Finite element analysis of the compaction plate from a garbage truck." E3S Web of Conferences 180 (2020): 04006. http://dx.doi.org/10.1051/e3sconf/202018004006.

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Vehicles that collect and transport household waste are equipped with complex systems that perform the loading of the waste from the stationary collection containers, take over and pre-compact of material, compaction in the body of the structure and finally the landfill of the collected waste. Of all these operations, the compaction process is by far the most mechanically demanding. In this paper, the structural analysis of the compactor plate from a garbage truck is presented. In the first stage it was carried out parametric modelling of the assembly composed of compactor plate, counter pressure plate, the back of the garbage truck and to be compacted material. After assembly, the dynamic simulation of the compaction process in the garbage truck was performed, and the compaction mechanical stresses for the compactor plate were loaded in the Simulation module of the SolidWorks 2016 program. Here the finite element analysis was performed, resulting in the value and dispersion of the equivalent stresses (calculated by von Mises criterion), displacements and relative deformations of compactor plate from the analysed garbage truck.

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Mohammadi, K., and Abolfazl Darvizeh. "Dynamic Model of Compaction Process of Metallic Powders." Advanced Materials Research 264-265 (June 2011): 155–59. http://dx.doi.org/10.4028/www.scientific.net/amr.264-265.155.

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Dynamic modeling of compaction process ,and evaluation of hardening parameters of powder compacts undergoing uni-axial/multi compaction is a tedious process and requires many elaborate tests .However ,assuming a two-parameter failure surface ( such as Mohr–Coulomb),evolution of failure surface may be monitored by two points on the failure surface. Results of uni-axial compression and direct or indirect tensile tests may readily provide the two required points. In order to assess this hypothesis ,a laboratory investigation was carried out using atomized iron powder(WPL-200) and aluminum powder(+160Mm) . Green compacts of the said drop-hammer , specifically designed for this purpose. Specimens with various relative compactions were produced and tested in uni-axial compression test and Brazilian split test .Variations of compressive/tensile strength with compaction energy(hammer speed) and relative density were studied and hardening law for green compacts were developed.

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Qian, Jing, and Ling Wei Meng. "Structural Analysis for Space-Swing Mechanism on Gyratory Compactor." Key Engineering Materials 621 (August 2014): 253–59. http://dx.doi.org/10.4028/www.scientific.net/kem.621.253.

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Based on the automatic dynamic analysis of mechanical systems software, both rigid and flexible models of the space-swing mechanism for the superpave gyratory compactor are developed. The structural analysis shows that the length and the initial phase of cranks, and the assembling accuracy (coordinates) of some points are very sensitive relative to the waving of compaction angle. Greater rigidity helps stabilize the change of the compaction angles.

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Day, Robert W. "Relative Compaction of Fill Having Oversize Particles." Journal of Geotechnical Engineering 115, no. 10 (October 1989): 1487–91. http://dx.doi.org/10.1061/(asce)0733-9410(1989)115:10(1487).

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Han, P., X. Z. An, Y. X. Zhang, and Z. S. Zou. "FEM modeling on the compaction of Fe and Al composite powders." Journal of Mining and Metallurgy, Section B: Metallurgy 51, no. 2 (2015): 163–71. http://dx.doi.org/10.2298/jmmb150210020h.

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The compaction process of Fe and Al composite powders subjected to single action die compaction was numerically modeled by FEM method. The relationship between the overall relative density and compaction pressure of the compacts with various Al contents was firstly identified, and the influences of Al content on the local relative density, stress, and their distributions were studied. Then the compaction pressure effects on the above properties with fixed Al content were discussed. Furthermore, detailed flow behaviors of the composite powders during compaction and the relationship between the compaction pressure and the ejection force/spring back of the compact were analyzed. The results show that: (1) With each compaction pressure, higher relative density can be realized with the increase of Al content and the relative density distribution tends to be uniform; (2) When the Al content is fixed, higher compaction pressure can lead to composite compact with higher relative density, and the equivalent Von Mises stress in the central part of the compact increases gradually; (3) Convective flow occurs at the top and bottom parts of the compact close to the die wall, each indicates a different flow behavior; (4) The larger the compaction pressure for each case, the higher the residual elasticity, and the larger the ejection force needed.

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Güner, Faruk. "Numerical Investigation of AISI 4140 Powder High Relative Density Compaction In Terms of Compaction Velocity." Mechanics 26, no. 1 (February 12, 2020): 5–11. http://dx.doi.org/10.5755/j01.mech.26.1.22862.

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In this study high relative density compaction of AISI 4140 steel powder compaction numerically investigated via different compaction velocities using Multi Particle Finite Element Method (MPFEM). 2D Analyses performed by three different particle geometry; 25µm, 35µm and 45µm in radius. Particle size effect also investigated via high relative density and compaction velocity. von Mises Power law evaluated for AISI 4140 steel powder and utilized to analysis. Results were plotted both in visually and graphically in aim to show effect of relative density, particle size, contact interactions and compaction velocity. The stress distribution through the height of die revealed out. A four-fold increase in compaction velocity increase the Equivalent von Mises stress 2% where the stress value can reach up to 3 times the yield stress. Stress values along the punch to the bottom of the die show a parabolic tendency with compaction velocity increase.

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Ngai, Tungwai Leo, Zhi Yu Xiao, Yuan Biao Wu, and Yuan Yuan Li. "Studies on Preparation of Ti₃SiC₂ Particulate Reinforced Cu Matrix Composite by Warm Compaction and Its Tribological Behavior." Materials Science Forum 534-536 (January 2007): 929–32. http://dx.doi.org/10.4028/www.scientific.net/msf.534-536.929.

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Conventional powder metallurgy processing can produce copper green compacts with density less than 8.3 g/cm3 (a relative density of 93%). Performances of these conventionally compacted materials are substantially lower than their full density counterparts. Warm compaction, which is a simple and economical forming process to prepare high density powder metallurgy parts or materials, was employed to develop a Ti3SiC2 particulate reinforced copper matrix composite with high density, high electrical conductivity and high strength. In order to clarify the warm compaction behaviors of copper powder and to optimize the warm compaction parameters, effects of lubricant concentration and compaction pressure on the green density of the copper compacts were studied. Copper compact with a green density of 8.57 g/cm3 can be obtained by compacting Cu powder with a pressure of 700 MPa at 145°C. After sintered at 1000°C under cracked ammonia atmosphere for 60 minutes, density of the sintered compact reached 8.83 g/cm3 (a relative density of 98.6%). Based on these fabrication parameters a Ti3SiC2 particulate reinforced copper matrix composite was prepared. Its density, electrical conductivity, ultimate tensile strength, elongation percentage and tribological behaviors were studied.

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Landrø, Martin, and Jan Stammeijer. "Quantitative estimation of compaction and velocity changes using 4D impedance and traveltime changes." GEOPHYSICS 69, no. 4 (July 2004): 949–57. http://dx.doi.org/10.1190/1.1778238.

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In some hydrocarbon reservoirs, severe compaction of the reservoir rocks is observed. This compaction is caused by production, and it is often associated with changes in the overburden. Time‐lapse (or 4D) seismic data are used to monitor this compaction process. Since the compaction causes changes in both layer thickness and seismic velocities, it is crucial to distinguish between the two effects. Two new seismic methods for monitoring compacting reservoirs are introduced, one based on measured seismic prestack traveltime changes, and the other based on poststack traveltime and amplitude changes. In contrast to earlier methods, these methods do not require additional empirical relationships, such as, for instance, a velocity‐porosity relationship. The uncertainties in estimates for compaction and velocity change are expressed in terms of errors in the traveltime and amplitude measurements. These errors are directly related to the quality and repeatability of time‐lapse seismic data. For a reservoir at 3000‐m depth with 9 m of compaction, and assuming a 4D timeshift error of 0.5 ms at near offset and 2 ms at far offset, we find relative uncertainty in the compaction estimate of approximately 50–60% using traveltime information only.

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Yu, Bangyong, Shucai Pan, and Kaisheng Xu. "Particle Crushing and Morphology Evolution of Saturated Crushed Gangue under Compaction." Advances in Civil Engineering 2020 (November 11, 2020): 1–10. http://dx.doi.org/10.1155/2020/8839302.

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In this research, the deformation, particle crushing, and morphology evolution of saturated crushed gangue under variable axial stresses (0, 2, 4, 8, 12, 16, and 20 MPa) were investigated by performing a series of laboratory tests with our self-designed compacting device. The research results showed that the relationship between compression modulus and axial stress can be expressed by an exponential function. The relative breakage varied from 0 to 0.3685 and increased monotonously with the increase of axial stress. The relation between relative breakage and axial strain was described by a linear function. The particle circularity varied from 1.179 to 1.361 and decreased gradually with the increase of axial stress. When the axial stress increased from 0 MPa to 2 MPa, the relative breakage increased rapidly by over 39.15% of the total increase, and the particle circularity of large particles in the range of 15–20 mm sharply decreased by over 48.34% of the total decrease. 2 MPa was a key value in controlling the particle crushing of the saturated crushed gangue during compaction. Particle crushing was predominantly divided into three types: fracture, crushing, and grinding. At the early stage of compaction, fracture and crushing took place in large numbers. At the end, grinding was the main form of particle crushing. The axial strain was influenced by the initial gradation, and a larger Talbot exponent corresponded to a larger strain. However, the initial gradation had little effect on the relative breakage.

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Razouki, Sabah S., and Dina K. Kuttah. "Effect of Relative Compaction on Water Absorption and Gypsum Dissolution in Gypsum-Rich Clayey CBR Samples." Transportation Infrastructure Geotechnology 7, no. 4 (April 11, 2020): 590–604. http://dx.doi.org/10.1007/s40515-020-00107-w.

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Abstract A clayey gypsiferous soil of CL group according to the Unified Soil Classification System was studied for the effect of relative compaction on water absorption and gypsum dissolution during long-term soaking. The soil has a gypsum content of about 33%. Two sets of soil samples were prepared at optimum moisture content of 11.75% of the modified Proctor compaction test. The first set received 100%, while the second received about 93.5% relative compaction with respect to modified Proctor. These samples were soaked for 4, 7, 15, 30, and 120 days under 40 lbs (178 N) surcharge load. The moisture content was determined at top, quarter points, midpoint, and bottom of each soil sample. The test results revealed that for each compaction effort, the moisture content along each soaked soil sample is not uniform and increased with increasing soaking period. This increase in moisture content is greater for soil samples compacted at the lower compaction effort. The moisture content at top of each soil sample is greater than at the bottom, and the least moisture content took place at the middle of the sample. The dissolution of gypsum, at the top of soil samples, was greater than that at the middle. A multiple regression equation was developed relating strongly the decrease in gypsum content along the clayey CBR samples, with compaction effort and increase in average moisture content along the samples due to soaking. Similarly, strong correlation was obtained from the multiple regression developed between absorbed water, soaking period, and compaction effort. The paper shows that the water absorption and gypsum dissolution decrease with increasing relative compaction as the soil becomes denser.

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Smolin, Yu P., and K. V. Vostrikov. "COMPACTION OF SATURATED SOILS WITH REGARD TO COMPRESSIBLE PORE FLUID AND SOIL CREEP." Vestnik Tomskogo gosudarstvennogo arkhitekturno-stroitel'nogo universiteta. JOURNAL of Construction and Architecture 21, no. 5 (October 29, 2019): 192–99. http://dx.doi.org/10.31675/1607-1859-2019-21-5-192-199.

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The paper describes the problem of consolidation of clay soil with spherical tensor and stress deviator, taking into account compressibility of pore fluid and the soil creep. In solving the problem, the differential equation is suggested for compacting cohesive soil filled with linearly compressible groundwater. It is considered that the gas volume in the groundwater does not exceed 10 %. The solution of the differential equation is based on the Fourier transform.For the numerical calculation of creep during compaction of consolidated soil an easy-touse method was used, i.e. testing of soil samples of the same monolith in the compression device, but different height. Knowing the relative vertical deformation of these samples, approximation and extrapolation methods allow to find the relative deformation at the sample height tending to zero. At almost zero sample thickness, deformation depends only on the soil creep, while the pore pressure will no longer play a role.The obtained values of the relative strain are used to select the function of the creep nucleus. It is found that the exponential function optimally describes the process of soil compaction over the entire area: from the beginning of compaction to its termination.Knowing the pressure, the stress in soil and the amount of sediment are found with a triaxial compression, taking into account its instantaneous deformation.

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Wang, Wenchao, Hui Qi, Pingan Liu, Yuanbo Zhao, and Hao Chang. "Numerical Simulation of Densification of Cu–Al Mixed Metal Powder during Axial Compaction." Metals 8, no. 7 (July 12, 2018): 537. http://dx.doi.org/10.3390/met8070537.

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The densification mechanism of Cu–Al mixed metal powder during a double-action die compaction was investigated by numerical simulation. The finite element method and experiment were performed to compare the effect of the forming method, such as single-action die compaction and double-action die compaction, on the properties of compact. The results showed that the latter could significantly raise the densification rate and were in good agreement with Van Der Zwan–Siskens compaction equation. The effects of the different initial packing structures on the properties of the compact were studied. The results showed that a high-performance compact could be obtained using a dense initial packing structure at a given compaction pressure. Additionally, the effects of the Al content and compaction pressure on the relative density and stress distribution were analyzed. It was observed that, with an increase in the Al content at a given compaction pressure, the relative density of the compact increased, whereas the stress decreased. Furthermore, when the Al content was fixed, the relative density and stress increased with increasing compaction pressure. The relationship between the relative density and the compaction pressure under different friction conditions was characterized and fitted according to the Van Der Zwan–Siskens compaction equation. The influence mechanisms of die wall friction on the compaction behavior were investigated. It was revealed that friction is a key factor that causes the inhomogeneity of the powder flow and stress distribution. Finally, the effects of the dwell time and height–diameter ratio on the densification behavior were analyzed, and it was found that an increase in the dwell time promoted the densification process, whereas an increase of the height–diameter ratio could hinder the process.

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Lim, Joong Yeon, Jung Min Seo, and Beong Bok Hwang. "A Numerical Analysis of Powdered Metal Compaction Processes for Two-Level Flanged Solid Cylindrical Components." Materials Science Forum 475-479 (January 2005): 3251–54. http://dx.doi.org/10.4028/www.scientific.net/msf.475-479.3251.

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A finite element method for the compaction process of metallic powder is introduced in the present work. Basic equations for the finite element formulation are summarized. A yield criterion, which is modified by describing asymmetric behavior of powder metal compacts, is introduced and applied to a certain class of powdered metal compaction processes. Two-level flanged solid cylindrical components are analyzed in three different compacting methods with three different compact geometries. The simulation results are summarized in terms of relative density distribution within compacts, pressure distributions along the die-wall interfaces, load-stroke relationships of each punch, average densities as functions of height and radius of the compact, respectively, and average densities of pin and head. For each compact from different compacting method, the best pressing method is chosen for uniform density distributions within the compact.

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Omar, Chalak S., Ranjit M. Dhenge, Stefan Palzer, Michael J. Hounslow, and Agba D. Salman. "Roller compaction: Effect of relative humidity of lactose powder." European Journal of Pharmaceutics and Biopharmaceutics 106 (September 2016): 26–37. http://dx.doi.org/10.1016/j.ejpb.2016.02.016.

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Mapfumo, E., D. S. Chanasyk, M. A. Naeth, and V. S. Baron. "Soil compaction under grazing of annual and perennial forages." Canadian Journal of Soil Science 79, no. 1 (February 1, 1999): 191–99. http://dx.doi.org/10.4141/s97-100.

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This study investigated the impact of heavy, medium and light grazing of meadow bromegrass an triticale on soil bulk density, relative compaction and penetration resistance. The study was conducted at Lacombe, Alberta, on a Orthic Black Chernozem of loam to silt loam texture. Sampling was conducted in fall 1995, spring 1996, fall 1996 and spring 1997. Core samples to a 15-cm depth were collected for measurement of bulk density and moisture content. Penetration resistance to 15 cm was measured with a hand-pushed cone penetrometer. The standard Proctor test was used to determine maximum bulk density. Relative compaction was the ratio of actual bulk density to the Proctor maximum bulk density expressed as a percentage. Surface (0–2.5 cm) bulk density and penetration resistance were significantly greater under heavily grazed than under medium and lightly grazed meadow bromegrass only for fall 1995. Differences in bulk density, relative compaction and penetration resistance for different grazing intensities in spring and fall 1996 and spring 1997 were either small or not significant. Generally, bulk density decreased over winter in the top 2.5 cm, was not consistent in the 5- to 10-cm depth interval and did not change in the 10- to 15-cm interval. Except in fall 1995, the relative compaction values for all grazing intensities and forage species were less than 90%, a value considered critical for plant growth. Generally, within each grazing level, there were minimal differences in bulk density, relative compaction and penetration resistance under triticale compared to those under meadow bromegrass. Key words: Bulk density, relative compaction, penetration resistance

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Twerdoff, D. A., D. S. Chanasyk, E. Mapfumo, M. A. Naeth, and V. S. Baron. "Impacts of forage grazing and cultivation on near-surface relative compaction." Canadian Journal of Soil Science 79, no. 3 (August 1, 1999): 465–71. http://dx.doi.org/10.4141/s98-076.

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The study was conducted at the Lacombe Research Station, Alberta, on an Orthic Black Chernozem of loam to silt loam texture to investigate grazing impacts and cultivation on near-surface soil compaction. Four forages, smooth bromegrass (Bromus inermis Leyss 'Carlton'), meadow bromegrass (Bromus riparius Rhem 'Paddock'), a mixture of triticale (X Triticosecale Wittmack 'Pika') and barley (Hordeum vulgare L. AC Lacombe), and triticale were used for the study. Each forage species was subjected to heavy, medium and light intensity grazing. Measurements of bulk density and volumetric moisture content for the 0- to 10-cm depth interval were conducted using a surface moisture-density probe between spring 1994 and fall 1996. Relative compaction was calculated as the actual bulk density expressed as a percentage of the Proctor maximum density. Relative compaction values for all treatments and that for the benchmark were less than 90%, which is considered critical for limiting plant growth. Cultivation reduced bulk density under annual forages by only 3% and lowered it under heavy grazed annual treatments most. Regression analysis conducted on the dependence of bulk density to cumulative cow-days indicated a curvilinear relationship. Bulk density increased more rapidly with increasing cumulative cow-days for annuals compared to perennials. From a management perspective, adopting intensive rotational grazing systems for perennial and annual forages may not cause any serious surface compaction problems for soils in this area. Key words: Annuals, bulk density, cow-days, grazing intensity, perennials, volumetric moisture content

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Brus, Dick J., and Jan J. H. van den Akker. "How serious a problem is subsoil compaction in the Netherlands? A survey based on probability sampling." SOIL 4, no. 1 (February 5, 2018): 37–45. http://dx.doi.org/10.5194/soil-4-37-2018.

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Abstract. Although soil compaction is widely recognized as a soil threat to soil resources, reliable estimates of the acreage of overcompacted soil and of the level of soil compaction parameters are not available. In the Netherlands data on subsoil compaction were collected at 128 locations selected by stratified random sampling. A map showing the risk of subsoil compaction in five classes was used for stratification. Measurements of bulk density, porosity, clay content and organic matter content were used to compute the relative bulk density and relative porosity, both expressed as a fraction of a threshold value. A subsoil was classified as overcompacted if either the relative bulk density exceeded 1 or the relative porosity was below 1. The sample data were used to estimate the means of the two subsoil compaction parameters and the overcompacted areal fraction. The estimated global means of relative bulk density and relative porosity were 0.946 and 1.090, respectively. The estimated areal fraction of the Netherlands with overcompacted subsoils was 43 %. The estimates per risk map unit showed two groups of map units: a “low-risk ” group (units 1 and 2, covering only 4.6 % of the total area) and a “high-risk” group (units 3, 4 and 5). The estimated areal fraction of overcompacted subsoil was 0 % in the low-risk unit and 47 % in the high-risk unit. The map contains no information about where overcompacted subsoils occur. This was caused by the poor association of the risk map units 3, 4 and 5 with the subsoil compaction parameters and subsoil overcompaction. This can be explained by the lack of time for recuperation.

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Cheng, Xiao Le, Yi Min Gao, Jian Dong Xing, Jian Yang, and Chong Gao Bao. "Preparation of Warm Compacted and Sintered WC/Carbon Steel Composite and its Wear-Resistance." Key Engineering Materials 336-338 (April 2007): 1342–45. http://dx.doi.org/10.4028/www.scientific.net/kem.336-338.1342.

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The WC particulates (0.076mm~0.100mm in size) and carbon steel (0.45wt% C) are selected as a reinforced phase and matrix in the composites. The techniques of warm compaction are systematically investigated with powder metallurgy solid phase sintering method. The performance of sliding friction wear of the composites is tested on a pin on disk tester. The test results of warm compaction show that the composites sample containing 50% WC and 50% steel possesses the perfect compaction density (9.4362g/cm3) and the relative density reaches 91.6% under the condition of 140°C compaction temperature, 320KN stress, and lubricated with zinc stearate. The results of wear test show that the composite sample under the condition of warm compaction gains the best wear property, and the relative wear resistance is the 2.9 times of 15Cr cast iron, 2.6 times of 20Cr cast iron and 2.8 times of the composite sample under the condition of room temperature compaction. And the wear mechanism of the particle-reinforced composites is analyzed using SEM.

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Zhao, Yihai, Maja Krzic, Chuck E. Bulmer, Margaret G. Schmidt, and Suzanne W. Simard. "Relative bulk density as a measure of compaction and its influence on tree height." Canadian Journal of Forest Research 40, no. 9 (September 2010): 1724–35. http://dx.doi.org/10.1139/x10-115.

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Soil compaction often limits conifer regeneration on sites degraded by landings and roads, but inadequate understanding of the relationship between compaction and tree growth could lead to inappropriate soil conservation and rehabilitation efforts. We tested liquid and plastic limits, oxidizable organic matter, total carbon, particle size distribution, and iron and aluminum oxides on soil samples collected from five forest experiments in interior British Columbia. These data were used to estimate soil maximum bulk density (MBD) and relative bulk density (RBD); our objective was to relate RBD to tree growth. Height of interior Douglas-fir ( Pseudotsuga menziesii var. glauca (Bessin) Franco) was limited when RBD was >0.72. For lodgepole pine ( Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) and hybrid white spruce ( Picea glauca (Moench) Voss × Picea engelmannii Parry ex Engelm.), RBDs of 0.60–0.68 corresponded to maximum height, whereas RBDs of 0.78–0.87 appeared to limit height growth. The presence of surface organic material mitigated compaction and was often associated with lower RBD. Our results illustrate the usefulness of RBD to assess compaction and suggest that soil rehabilitation should be considered on disturbed sites where soil RBD is >0.80.

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Wong, RJ, MS Roy, and JEK Byrnes. "Sediment selection: range-expanding fiddler crabs are better burrowers than their historic-range counterparts." Marine Ecology Progress Series 674 (September 16, 2021): 163–71. http://dx.doi.org/10.3354/meps13811.

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Climate change plays a large role in driving species range shifts; however, the physical characteristics of an environment can also influence and alter species distributions. In New England salt marshes, the mud fiddler crab Minuca pugnax is expanding its range north of Cape Cod, MA, into the Gulf of Maine (GoM) due to warming waters. The burrowing lifestyle of M. pugnax means sediment compaction in salt marshes may influence the ability of crabs to dig, with more compact soils being resistant to burrowing. Previous studies indicate that salt marshes along the GoM have a higher sediment compaction relative to marshes south of Cape Cod. Physical characteristics of this habitat may be influencing the burrowing performance of M. pugnax and therefore the continuation of their northward range expansion into the GoM. We conducted a controlled laboratory experiment to determine if compaction affects the burrowing activity of M. pugnax in historical and range-expanded populations. We manipulated sediment compaction in standardized lab assays and measured crab burrowing performance with individuals collected from Nantucket (NAN, i.e. historical range) and the Plum Island Estuary (PIE, i.e. expanded range). We determined compaction negatively affected burrowing ability in crabs from both sites; however, crabs from PIE have a higher probability of burrowing in higher sediment compactions than NAN crabs. In addition, PIE crabs were more likely to burrow overall. We conclude that site level differences in compaction are likely altering burrowing behavior in the crab’s expanded-range territory by way of local adaptation or phenotypic plasticity.

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Zhang, Bao, Idris K. Mohammed, Yi Wang, and Daniel S. Balint. "On the use of HCP and FCC RVE structures in the simulation of powder compaction." Journal of Strain Analysis for Engineering Design 53, no. 5 (May 10, 2018): 338–52. http://dx.doi.org/10.1177/0309324718774188.

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Use of hexagonal close packed and face centered cubic structures to simulate powder compaction reveals that plastic deformation is effective in reducing porosity until a relative density of 0.96, beyond which a drastic rise in pressure is required. The compaction process can be divided into three phases demarcated by relative densities of 0.8 and 0.92, characterized, respectively, by local yielding around the initial contact point, coalescence of locally yielded zones and full plastic flow to reduce pores. The macroscopic yield behaviour of the powder assembly in the present work agrees reasonably with analytical and numerical models such as the Storåkers-Fleck-McMeeking model and multi-particle finite element model. It is found that for rate-dependent powder materials, the compaction process is noticeably rate dependent from a relative density of 0.85. Although a regular packing of powders is unrealistic, the understanding gained from a regular packing model provides insight into the role that plastic deformation plays during powder compaction.

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Ko, B. D., D. H. Jang, Hyoung Jin Choi, Joong Yeon Lim, and Beong Bok Hwang. "Finite Element Method in Powdered Metal Compaction Processes." Materials Science Forum 449-452 (March 2004): 109–12. http://dx.doi.org/10.4028/www.scientific.net/msf.449-452.109.

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A finite element method for the compaction process of metallic powder is introduced in the present work. Basic equations for the finite element formulation are summarized. A yield criterion, which is modified by describing asymmetric behavior of powder metal compacts, is introduced and applied to various classes of powdered metal compaction processes. Three material parameters are involved in the yield function and determined from the behavior of sintered powder compacts as a function of relative density. The FEM simulation includes single-action and double-action pressings of solid cylinders as well as cylindrical rings of relatively long parts (Class II parts). The compaction process for multi-level flanged components (Class III and Class IV parts) is also analyzed. The predicted results from simulations are summarized in terms of density distributions within the compacts and pressure distributions exerted on the die-wall interfaces, and also in terms of effectiveness with increased relative motions with in the compacts and the effect of various compaction schemes of combination of punch motions. Results obtained in the multi-level compaction process are discussed in terms of average relative density distributions at each height.

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Zhong, Ji Xiang. "Subgrade Compaction Boundary Layer Detection Method and Detection System." Advanced Materials Research 639-640 (January 2013): 1259–64. http://dx.doi.org/10.4028/www.scientific.net/amr.639-640.1259.

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At present, the degree of compaction is the main criterion for subgrade compaction quality.It is the relative expression of the compacted density,Just average.It does not adequately reflect the subgrade compaction layer vertical compaction density distribution law. Compaction boundary layer micro-unit compression pressure on in the process of pressure transmission decreases gradually until they reach the critical formation pressure dense layer. Compaction by detecting the boundary layer vertical zone layer densification, to calculate the boundary thickness, to draw isodense of densification. a clear reproduction of the compacted layer vertical compaction density distribution law. This paper describes the detection principles and detection methods of the compaction boundary layer. describes in detail functional structure and system design of the vehicle automatic detection system used to detect compaction boundary layer of each vertical zone.

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Xiao, Yuanjie, Meng Wang, Xiaoming Wang, Juanjuan Ren, Weidong Wang, and Xiaobin Chen. "Evaluating Gyratory Compaction Characteristics of Unbound Permeable Aggregate Base Materials from Meso-Scale Particle Movement Measured by Smart Sensing Technology." Materials 14, no. 15 (July 31, 2021): 4287. http://dx.doi.org/10.3390/ma14154287.

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The quality of compaction of unbound aggregate materials with permeable gradation plays a vital role in their field performance; however, there are currently few unanimously accepted techniques or quality control criteria available for ensuring adequate compaction of such materials in either laboratory or field applications. This paper presented testing results of a laboratory gyratory compaction study where the combinations of gyratory parameters were properly designed using the orthogonal array theory. Innovative real-time particle motion sensors were employed to record particle movement characteristics during the compaction process and provide a meso-scale explanation about compaction mechanisms. Particle abrasion and breakage were also quantified from particle shape digitized from the three-dimensional (3D) laser scanner before and after compaction. The optimal combination of gyratory parameters that yields the best compaction performance was determined from the orthogonal testing results with the relative importance of major influencing parameters ranked accordingly. Meso-scale particle movement at the upper center and center side positions of the specimen are promising indicators of compaction quality. The gyratory compaction process can be consistently divided into three distinct stages according to both macro-scale performance indicators and meso-scale particle movement characteristics. A statistically significant bi-linear relationship was found to exist between relative breakage index and maximum abrasion depth, whereas the quality of compaction and the extent of particle breakage appear to be positively correlated, thus necessitating the cost-effective balance between them. The results of this study could provide technical insights and guidance to field compaction of unbound permeable aggregates.

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Ekwue, E. I., and R. J. Stone. "Irrigation Scheduling for Sweet Maize Relative to Soil Compaction Conditions." Journal of Agricultural Engineering Research 62, no. 2 (October 1995): 85–94. http://dx.doi.org/10.1006/jaer.1995.1067.

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Battigelli, Jeffrey P., John R. Spence, David W. Langor, and Shannon M. Berch. "Short-term impact of forest soil compaction and organic matter removal on soil mesofauna density and oribatid mite diversity." Canadian Journal of Forest Research 34, no. 5 (May 1, 2004): 1136–49. http://dx.doi.org/10.1139/x03-267.

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This study examines the short-term impact of forest soil compaction and organic matter removal on soil mesofauna, in general, and oribatid mite species, in particular. Both soil compaction and organic matter removal reduced the density of soil mesofauna. Stem-only harvesting reduced total mesofauna densities by 20% relative to uncut forest values. A combination of whole-tree harvest and forest floor removal with heavy soil compaction significantly reduced total soil mesofauna densities by 93% relative to the uncut forest control. Removal of the forest floor represents a substantial loss of habitat for most soil mesofauna. The forest floor apparently buffered the mineral soil by limiting both the impact of soil compaction and fluctuations in soil temperature and moisture. The relative abundance of Prostigmata and Mesostigmata increased with treatment severity, whereas that of Oribatida decreased. Species richness of the oribatid mite fauna was reduced as the severity of treatments increased. The number of rare oribatid species (those representing <1% of the total oribatid mite sample) decreased by 40% or more relative to the uncut forest control. Evenness also decreased as treatment severity increased. Oppiella nova and Suctobelbella sp. near acutidens were the dominant oribatid species in both the forest floor and mineral soil, regardless of treatment. Soil compaction and organic matter removal significantly impacted the density and diversity of soil mesofauna and oribatid mite fauna in the short term at these study sites.

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Ta, Dung Quoc, and Peter Behrenbruch. "ESTIMATION OF NEW RELATIVE PERMEABILITY CURVES DUE TO COMPACTION CASE STUDY AT BACHAQUERO FIELD – VENEZUELA." Science and Technology Development Journal 14, no. 2 (June 30, 2011): 38–53. http://dx.doi.org/10.32508/stdj.v14i2.1916.

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This paper is written to analyse the variation of water production due to compaction in a field in Venezuela. The producing water, after being analysed, was suspected not from aquifer. So where does the water come from? The results shows that pore structures of reservoir changed, and producing water is due to volume changes of immobile water and mobile water as the result of compaction. It means that relative permeability curves have changed when rock deforms.

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Tatsuoka, Fumio, and Toru Miura. "Compacted states and physical properties of soil controlled by the degree of saturation during compaction." E3S Web of Conferences 92 (2019): 18002. http://dx.doi.org/10.1051/e3sconf/20199218002.

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For satisfactory performance of soil structures, it is necessary to properly control soil compaction ensuring the physical properties of compacted soil required in design. Usually the dry density ρd and the water content w are controlled in relation to the maximum dry density (ρd)max and the optimum water content wopt determined by laboratory compaction tests on a chosen representative sample at a certain compaction energy level CEL. Although CEL and soil type affect significantly (ρd)max, wopt and physical properties, they change inevitably, sometimes largely, in a given project while field CEL may not match the value used in the laboratory compaction tests. In comparison, the optimum degree of saturation (Sr)opt (i.e., Sr when (ρd)max is obtained) and the normalized compaction curve (i.e., ρd/(ρd)max vs. Sr - (Sr)opt relation) for given CEL and soil type are insensitive to variations in CEL and soil type and they are essentially fixed in a given project. Besides, the stress-strain and hydraulic properties of compacted soil are controlled by ρd and “Sr at the end of compaction relative to (Sr)opt”. It is proposed to control w and CEL so that Sr= (Sr)opt while ρd becomes large enough to ensure the physical properties required in design fully taking advantage of available field CEL on site. A case history of earth-fill dam construction in Japan following this soil compaction control method is reported.

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Muthuraja, A., and S. Senthilvelan. "Compaction Characteristics of Tungsten Carbide Based Self-Lubricant Cutting Tool Material." Applied Mechanics and Materials 592-594 (July 2014): 87–91. http://dx.doi.org/10.4028/www.scientific.net/amm.592-594.87.

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In this study, an attempt has been made to develop solid lubricant cutting tool material with the aid of powder metallurgy technique. Chosen tungsten carbide, cobalt and calcium fluoride were milled in the planetary ball milling, followed by uniaxial compaction and sintering in a tube furnace. Materials were milled at various hours of milling and compaction pressure to understand the effect of relative density and hardness of sintered specimens. It is found that the relative density of compacted and sintered specimens found to increase with the compaction pressure but decreased with milling time after particular time. From the investigation, 40 hr of milling and 400 MPa compaction pressure found to be suitable for the development of proposed material. In this work, sample density was measured by the Archimedes’ method and hardness was measured by Rockwell hardness tester.

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Schaerer, Magna Monteiro, Deane Roehl, and José Luís Silveira. "Numerical Analysis of Metal Powders in Uniaxial Compaction." Materials Science Forum 591-593 (August 2008): 218–22. http://dx.doi.org/10.4028/www.scientific.net/msf.591-593.218.

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Powder consolidation constitutes an important step in the manufacture of products of high quality and precision. To obtain these components, with desired forms and final mechanical properties, it is of extreme importance to have knowledge about the processes to obtain powders, compacting and sintering. The objective of this work is to verify which model, obtained from the literature, better describes the compaction densification behavior of iron powder in closed-die. Doraivelu’s criterion was carried through the method of the finite elements with the implementation of an elastoplastic model with hardening. The influence of the yield function coefficient against the relative density was evaluated, as well as, the yield function in the hydrostatic space.

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Ardestani, Mohammad, Mohsen Rafiei, Sina Salehian, Mohammad Reza Raoufi, and Mohammad Zakeri. "Compressibility and solid-state sintering behavior of W-Cu composite powders." Science and Engineering of Composite Materials 22, no. 3 (May 1, 2015): 257–61. http://dx.doi.org/10.1515/secm-2013-0159.

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AbstractIn this research, compressibility and the effect of cold compaction pressure on sintered density of tungsten (W)-15% wt copper (Cu) and W-75% wt Cu composite powders were investigated. The powders were prepared by milling and reduction of WO3/CuO powder mixtures. The crystalline size and lattice strain of WO3 and CuO were determined using Debye-Scherrer’s formula after mechanical milling. Heckel and Panelli-Ambrosio equations were used to evaluate cold compaction behavior of the reduced powders. The results showed that Heckel equation represents better correlation between compaction pressure and relative density of W-75% wt Cu composite powders. However, it was confirmed that the preferred relation for evaluating the compaction behavior of W-15% wt Cu composite powders is Panelli-Ambrosio equation. The green compacts were sintered at 1000°C. It was shown that, by increasing the cold uniaxial pressure prior to sintering, the difference between green and sintered densities of W-15% wt Cu composite powder compacts was decreased. However, the W-75% wt Cu powders showed a different manner and higher compaction pressures led to higher densification during sintering.

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Kim, Y. H., Xiang Ma, H. C. Baek, and Chang Hwy Lim. "Stress Analysis of Cold Die Compaction with Rotating Tools for Aluminum Powder." Key Engineering Materials 340-341 (June 2007): 1375–80. http://dx.doi.org/10.4028/www.scientific.net/kem.340-341.1375.

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In this paper, a modified slab analysis has been used to determine the pressure distribution in the cylindrical compaction of aluminum powder under rotating die compaction. The analytical results are discussed to explain the pressure distribution and the interaction of the various parameters. To predict the density distribution in a powder compact under an applied pressure with torsion, the pressure function is coupled with some form of a pressure density relationship. High relative density can be realized in powder compacts by the rotating die compaction in contrast to the conventional compaction. A numerical analysis, using the DEFORM3D simulation software, is also carried out on the compaction under the rotating punch.

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Sevillano, J. Gil. "Size effects in powder compaction." Journal of Materials Research 16, no. 5 (May 2001): 1238–40. http://dx.doi.org/10.1557/jmr.2001.0172.

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It is well known that great difficulties are encountered in the cold compaction of ultrafine powders. Such difficulties have been qualitatively attributed to several origins (e.g., increasing relative contribution of oxidized layers to particle resistance as particle size decreases). The main densification stage during compaction is governed by plastic deformation at interparticle contacts under pressure. On account of the strength enhancement of plastic resistance in presence of plastic strain gradients (physically resolved by “geometrically necessary dislocations”) a contribution to the size effect on powder compaction efficiency is here predicted. Some quantitative experimental data available are in good agreement with this explanation.

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Agnelli, Marco, Bruno Huet, Vincent Briaud, Elodie André, and Alexander Pisch. "Some Insights on the Role of Relative Humidity and Compaction on the Carbonation Rate of CaO/SiO₂ (50/50) Clinker." Key Engineering Materials 711 (September 2016): 837–43. http://dx.doi.org/10.4028/www.scientific.net/kem.711.837.

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This paper focuses on the carbonation of non-hydraulic binders based primarily on wollastonite (CaSiO3) in order to study the relationship between clinker composition, curing conditions and compaction on carbonation reaction rate. Decoupled carbonation and drying experiments are carried out using cements at different CaO/SiO2 ratio, at 60 °C, 1 bar of CO2 and multiple RH (relative humidity) and compaction degrees. Solid analysis include mass gain or loss, TGA, XRF and Carbon/Hydrogen (CH) to determine respectively the bound H2O content, CO2 content and the mineralogical assemblage. Relative humidity strongly influences carbonation intrinsic reaction rate, while compaction seems to be a second order mechanism. Testing procedure can be used to discriminate the reactivity of clinkers with various initial phase assemblage.

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Liu, Yu, and Carl Wassgren. "Modifications to Johanson's roll compaction model for improved relative density predictions." Powder Technology 297 (September 2016): 294–302. http://dx.doi.org/10.1016/j.powtec.2016.04.017.

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Al-Obaidi, Anwar Luay, Mustafa A. Yousif, and ALaa Ihssan Hamid. "Effect of Relative Compaction on the Bearing Capacity of Cohesive Soils." IOP Conference Series: Materials Science and Engineering 737 (March 6, 2020): 012108. http://dx.doi.org/10.1088/1757-899x/737/1/012108.

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Suits, L. D., T. C. Sheahan, Norman W. Facas, Robert V. Rinehart, and Mike A. Mooney. "Development and Evaluation of Relative Compaction Specifications Using Roller-Based Measurements." Geotechnical Testing Journal 34, no. 6 (2011): 102915. http://dx.doi.org/10.1520/gtj102915.

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Hawley, Robert L., and Edwin D. Waddington. "In situ measurements of firn compaction profiles using borehole optical stratigraphy." Journal of Glaciology 57, no. 202 (2011): 289–94. http://dx.doi.org/10.3189/002214311796405889.

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AbstractWe have developed a technique in which we use a borehole video camera and post-processing software to make a record of the optical brightness as a function of depth in polar firn. We call this method borehole optical stratigraphy. To measure firn compaction, we note the positions of optical features on the borehole wall detected by an initial ‘baseline’ log. We track the displacements of these features in subsequent logs. The result provides a measurement of the relative vertical motion and thus compaction of the firn over the survey period. We have successfully used this system at Summit, Greenland, to measure the depth distribution of firn column shortening experienced in a borehole over three 1 year periods. The uppermost 30 m of the firn at Summit is compacting as predicted by a simple steady-state model, implying that the firn density profile at Summit is at or close to steady state over the past ∼70 years.

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Zohoor, Mehdi, and A. Mehdipoor. "Numerical Simulation of Underwater Explosive Compaction Process for Compaction of Tungsten Powder." Materials Science Forum 566 (November 2007): 77–82. http://dx.doi.org/10.4028/www.scientific.net/msf.566.77.

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Underwater explosive compaction is a modified explosive compaction process that is used for manufacturing of parts by compaction of hard powders such as tungsten powder. In the present research work, equation of state (EOS) for tungsten powder was determined by a theoretical method and numerical simulation of the underwater explosive compaction process for tungsten powder was done using LS-DYNA program. The simulation results were utilized for the optimization of die design setups, which were used in our experimental test. Several experiments for compaction of tungsten amorphous powder with a mean grain size about 5 microns were performed using C4 explosive with a detonation velocity about 8.2 km/s. The hardness and density of consolidated samples were determined. The fragmented surfaces of samples were analyzed by scanning electron microscope (SEM). The experimental results indicated the usefulness of computer simulation for optimization of die design and the process parameters. In addition, the results indicated that the tungsten parts without cracks and with a high relative hardness and density could be obtained by underwater explosive compaction method.

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Morales, R., S. Seetharaman, and V. Agarwala. "Mechanical and structural characterization of uniaxially cold-pressed Fe2Mo powders." Journal of Materials Research 17, no. 8 (August 2002): 1954–59. http://dx.doi.org/10.1557/jmr.2002.0289.

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In this work, Fe2Mo intermetallic powder, produced by H2 gas reduction of Fe2MoO4 was characterized by techniques like x-ray diffraction (XRD) and transmission electron microscopy (TEM). The TEM studies confirmed the presence of nano- and microcrystalline grains of Fe2Mo. The above powders when compressed uniaxially showed a logarithmic relation with “relative density”, δr, of the compacts. The multiple compaction mechanisms were analyzed by Kawakita's and Balshin's models. Vickers hardness number, VHN, was found to increase linearly with δr of the compacts. The hardness of Fe2Mo intermetallic when δr = 1 was estimated as 343 VHN. Using Tabor's analysis, the yield strength of Fe2Mo was found to be about 1100 MPa. This value was further confirmed from the details of relative broadening (112) Bragg peak of Fe2Mo obtained from XRD analyses of Fe2Mo at different compaction pressures.

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Nooren, Kees, Kim M. Cohen, Jaap H. Nienhuis, and Wim Z. Hoek. "Late Holocene differential subsidence and relative sea level rise in the Tabasco Delta, Mexico." Proceedings of the International Association of Hydrological Sciences 382 (April 22, 2020): 149–53. http://dx.doi.org/10.5194/piahs-382-149-2020.

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Abstract. Coastal subsidence owing to compaction of Holocene strata and deeper-rooted components affects large delta plains such as the Tabasco delta in southern Mexico (Gulf coast). For this system, GNSS3-PPP ground-truthed LiDAR imagery of high-resolution dated beach-ridge series reveals considerable differential subsidence on either side of the present Usumacinta-Grijalva River mouth. Collected field-data allows for quantification of differential subsidence over several time windows and reconstruction of relative sea-level rise back to 5000 years ago. Observed differential subsidence of 1–1.5 m is regarded to be syn-sedimentary delta-subsurface compaction of buried strata in response to the accumulating overburden of the prograding beach-ridge complex.

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Yuan, Xianjie, Xuanhui Qu, Haiqing Yin, Zhenwei Yan, and Zhaojun Tan. "Effects of Compaction Velocity on the Sinterability of Al-Fe-Cr-Ti PM Alloy." Materials 12, no. 18 (September 16, 2019): 3005. http://dx.doi.org/10.3390/ma12183005.

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In this research, the effects of the compaction velocity on the sinterability of the Al–Fe–Cr–Ti powder metallurgy (PM) alloy by high velocity compaction were investigated. The Al–Fe–Cr–Ti alloy powder was compacted with different velocities by high velocity compaction and then sintered under a flow of high pure (99.999 wt%) nitrogen gas. Results indicated that both the sintered density and mechanical properties increased with increasing compaction velocity. By increasing the compaction velocity, the shrinkage of the sintered samples decreased. A maximum sintered density of 2.85 gcm−3 (relative density is 98%) was obtained when the compaction velocity was 9.4 ms−1. The radial and axial shrinkage were controlled to less than 1% at a compaction velocity of 9.4 ms−1. At a compaction velocity of 9.4 ms−1, sintered compacts with an ultimate tensile strength of 222 MPa and a yield strength of 160 MPa were achieved. The maximum elongation was observed to be 2.6%. The enhanced tensile properties of the Al–Fe–Cr–Ti alloy were mainly due to particle boundary strengthening.

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Yin, Jian-Hua. "Influence of relative compaction on the hydraulic conductivity of completely decomposed granite in Hong Kong." Canadian Geotechnical Journal 46, no. 10 (October 2009): 1229–35. http://dx.doi.org/10.1139/t09-053.

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The relative compaction (RC) parameter is commonly used for assessment of the degree of compaction of existing fill slopes and (or) for the design and construction of new fill slopes. This technical note presents the results of an experimental study on the relationship of RC with the saturated hydraulic conductivity (ksat) of typical completely decomposed granite (CDG) in Hong Kong. The results are interpreted and discussed. Useful correlations of RC versus ksat and void ratio (e) versus ksat are obtained. It is found that the RC has a significant influence on ksat of CDG. The influence of RC is equivalent to the influence of e on ksat of the soil.

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Li, Jian, and Bin Ting Yang. "Influence of Temperature and Stress Factors on Warm Compaction Process of Molybdenum Powder Density." Advanced Materials Research 341-342 (September 2011): 119–23. http://dx.doi.org/10.4028/www.scientific.net/amr.341-342.119.

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Utilization of finite element method (FEM) and warm compaction process, study on mechanical theory and FEM simulation of molybdenum powder processing. The typical warm compaction process of molybdenum powder was simulated and analyzed with MSC.Marc FEM software. Via calculating, stress field, relative density distribution of molybdenum powder and temperature field were obtained. The result show that when velocity is 5mm/s and pressure is 1000MPa densification is the best. In the molybdenum powder compaction process volume percent of densification zone is 75%.

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Sandeep, Ujjwal Prakash, P. C. Tewari, and Dinesh Khanduja. "Analysis of Powder Metallurgy Process Parameters for Relative Density of Low Carbon Alloy Steel Using Design of Experiments Tool." Applied Mechanics and Materials 592-594 (July 2014): 72–76. http://dx.doi.org/10.4028/www.scientific.net/amm.592-594.72.

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The main aim of present research paper is to analyze the influence of compaction load and sintering temperature on relative density of low carbon alloy steel. The alloy steel powder has been compacted at different loads and sintering at different temperatures. The compaction of alloy steel has been done with a circular die of 20 mm internal diameter and 100 mm height at different load and sintering temperature. With the application of hydrostatic stress, the pores will be removed and relative density will increase. So, relative density value will increase simultaneously. This experimental study presents how relative density can be improved by using Powder Metallurgy route. The results are further analyzed with the help of Analysis of Variance using Design of Experiments Tool.

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Wang, Defeng, Xizhong An, Peng Han, Haitao Fu, Xiaohong Yang, and Qingchuan Zou. "Particulate Scale Numerical Investigation on the Compaction of TiC-316L Composite Powders." Mathematical Problems in Engineering 2020 (February 29, 2020): 1–13. http://dx.doi.org/10.1155/2020/5468076.

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This paper presents a numerical investigation on the 2D uniaxial die compaction of TiC-316L stainless steel (abbreviated by 316L) composite powders by the multiparticle finite element method (MPFEM). The effects of TiC-316L particle size ratios, TiC contents, and initial packing structures on the compaction process are systematically characterized and analyzed from macroscale and particulate scale. Numerical results show that different initial packing structures have significant impacts on the densification process of TiC-316L composite powders; a denser initial packing structure with the same composition can improve the compaction densification of TiC-316L composite powders. Smaller size ratio of 316L and TiC particles (R316L/RTiC = 1) will help achieve the green compact with higher relative density as the TiC content and compaction pressure are fixed. Meanwhile, increasing TiC content reduces the relative density of the green compact. In the dynamic compaction process, the void filling is mainly completed by particle rearrangement and plastic deformation of 316L particles. Furthermore, the contacted TiC particles will form the force chains impeding the densification process and cause the serious stress concentration within them. Increasing TiC content and R316L/RTiC can create larger stresses in the compact. The results provide valuable information for the formation of high-quality TiC-316L compacts in PM process.

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Molotnikov, Andrey, Rimma Lapovok, Tao Peng, and Yuri Estrin. "Comparison of Different Extrusion Methods for Compaction of Powders." Materials Science Forum 667-669 (December 2010): 57–62. http://dx.doi.org/10.4028/www.scientific.net/msf.667-669.57.

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Densification of metallic powders by means of extrusion is regarded as a very attractive processing technique that allows obtaining a high level of relative density of the compact. However, the uniformity of the relative density depends on that of strain distribution and on the processing parameters. Several variants of extrusion can be used for compaction of metal particulates, including the conventional extrusion (CE) and equal channel angular pressing (ECAP), often referred to as equal-channel angular extrusion. Each of these processes has certain advantages and drawbacks with respect to compaction. A comparative study of these two extrusion processes influencing the relative density of compacts has been conducted by numerical simulation using commercial finite element software DEFORM2D. The results have been validated by experiments with titanium and magnesium powders and chips.

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Scherbakov, V. V., A. P. Karpik, I. V. Scherbakov, M. N. Barsuk, and I. A. Buntsev. "Geodetic technologies for monitoring ballast compaction parameters during the construction and overhaul of railways using global navigation satellite system." Geodesy and Cartography 961, no. 7 (August 20, 2020): 8–13. http://dx.doi.org/10.22389/0016-7126-2020-961-7-8-13.

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The development of a monitoring system based on global satellite navigation systems (GNSS) of ballast compaction quality during the construction and overhaul of railways is covered in the article. Traditional geodetic methods for determining the quality of ballast compaction are tedious. Non-geodetic methods (dynamic control systems, empirical models and geophysical methods) are not widely used on railways due to the low reliability of the ballast compaction quality, as well as the high complexity of the work. The proposed method and device of a quality control system for ballast compaction are based on the measurement of draft and residual deformations during compaction in dynamic mode. The current coordinates are determined using GNSS with dual-antenna positioning receivers performing advanced functions, including determining the relative position of the antennas in plan and height. The monitoring system developed at the Siberian State University of Railway Engineering enables real-time determining parameters which characterize the quality of compaction with high accuracy and the ability of controlling the compaction process according to the current parameters.

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Eskandari, H., and R. Gholamipouri. "Properties of Nd-Fe-B Powder Explosively Compacted." Materials Science Forum 673 (January 2011): 237–42. http://dx.doi.org/10.4028/www.scientific.net/msf.673.237.

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Nd-Fe-B magnets are used in wide range of industrial applications. In this research we studied the possibility of producing bulk Nd-Fe-B magnetic compact by using the direct cylinder explosive compaction. After compaction the density of compact was measured by the Archimedes method. Highly dense compact (> 98% relative density) without cracks was obtained by this technique. A concentric hole was observed at center of some compacts. The magnetic properties of the compact are Br=7.95KG, iHc=10.5kOe, (BH)max= 14MOe, and these values are same as those before explosive compaction.

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Journal articles on the topic 'Relative compaction'

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