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1
Juárez Alvarado, César Antonio, Javier Rodrigo Gonzalez Lopez, José Manuel Mendoza, and Antonio Alberto Zaldivar Cadena. "Low impact fiber reinforced material composite." Revista ALCONPAT 7, no. 2 (May 31, 2017): 135–47. http://dx.doi.org/10.21041/ra.v7i2.189.
Повний текст джерелаАнотація:
Low impact fiber reinforced material compositeABSTRACTThis article investigates the mechanical behavior of fiber-reinforced cementitious composites using moderate to high contents of fly ash (FA) as a replacement for cement; the goal is to create primary building elements with low environmental impact. The experimental results showed that the compressive strength, modulus of elasticity, and post-cracking flexural strength for specimens with w/cm = 0.60 and 20% FA substitution increased with respect to the control. Moreover, the specimens with high FA substitutions had significantly lower mechanical strength values and elastic modulus values. The results indicate that it is feasible to use fiber-reinforced concrete composites as an alternative for low-environmental impact primary construction.Keywords: fiber; cementitous; composites; fly ash, impact material.
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Nan, Senlin, Wentao Li, Weiming Guan, Huabin Liu, Hongchao Zhao, Yingyuan Wen, and Junhui Yao. "Research on the Rapid Strengthening Mechanism of Microwave Field-Controlled Gypsum-Cemented Analog Materials." Minerals 11, no. 12 (November 30, 2021): 1348. http://dx.doi.org/10.3390/min11121348.
Повний текст джерелаАнотація:
Various geotechnical experiments have used gypsum-cemented analog geotechnical materials. However, this material needs a long curing time, and the target strength is not easy to control. Therefore, this research adopted microwave heating as the curing method for this kind of material. Objectively, the authors investigated the variations in the material strength versus heating power and heating time. On this basis, we clarified the influence mechanism of microwaves on the strength of analog materials by analyzing material temperature, moisture content, and microstructure, which eventually led to an experimental control method for rapid strengthening of microwave field-controlled gypsum-cemented analog materials. Consequently, we drew the following conclusions. The stable strength of the material under high-power microwave curing was much lower than that under natural curing, while the material strength under low-power microwave curing was the closest to the material under natural curing.
3
Shi, Yaobin, Yicheng Ye, Nanyan Hu, Xu Huang, and Xianhua Wang. "Experiments on Material Proportions for Similar Materials with High Similarity Ratio and Low Strength in Multilayer Shale Deposits." Applied Sciences 11, no. 20 (October 15, 2021): 9620. http://dx.doi.org/10.3390/app11209620.
Повний текст джерелаАнотація:
It is important to systematically investigate the similar materials with high similarity ratio and low strength in multilayer shale deposits, to provide a scientific basis and experimental basis for the research of underground mining of multilayer shale deposits. In this paper, using an orthogonal experimental method, the physical and mechanical parameters of different material proportions were analyzed with four control factors of mica powder/standard sand, filling material/bonding material, Portland cement/gypsum, silicone oil ratio. Twenty-five groups of material proportioning schemes were designed, and the density, porosity, compressive strength, and elastic modulus of each group of materials were measured. Through the range analysis and significance analysis, the influence of control factors on the material parameters was explored, and multivariate linear regression analysis of test results was carried to eliminate outliers. The result showed that the physical and mechanical parameters of similar materials prepared according to the proportioning scheme were widely distributed, which can meet the preparation requirements of similar materials with different lithologies. The density and compressive strength were most affected by the ratio of Portland cement/gypsum, the porosity was most affected by the ratio of filling material/bonding material, and the elastic modulus was mainly controlled by the silicone oil ratio. The proportioning scheme was applied to three similar prepared shale materials with large lithology differences. The error between actual similar constant and design similar constant of low strength similar material was less than 1.62%. The physical and mechanical parameters of similar materials were in good agreement with the original rock.
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IVANNIKOV, Sergei I., Yana A. VAHTEROVA, Yuri A. UTKIN, and Ying SUN. "Calculation of strength, rigidity, and stability of the aircraft fuselage frame made of composite materials." INCAS BULLETIN 13, S (August 3, 2021): 77–86. http://dx.doi.org/10.13111/2066-8201.2021.13.s.8.
Повний текст джерелаАнотація:
Carbon-carbon composite materials (CCCM) are characterized by high heat resistance and thermostability for which they, in most of their physical and mechanical characteristics, can be attributed to the most promising materials. Approximately 81% of all carbon-carbon composite materials are used for the manufacture of brake rotors for aircraft, 18% – in space rocket technology, and only 1% – for all other areas of application. This study discusses calculations of the strength, rigidity, and stability of a frame made of carbon-carbon composite materials. It is known that the strength of CCCM based on high-strength carbon fibers is higher than the strength of a composite material based on high-modulus carbon fibers obtained at various processing temperatures. The stress-strain behaviour (SSB) of the material is carried out. Among the special properties of CCCM are low porosity, low coefficient of thermal expansion, maintaining a stable structure and properties, as well as product dimensions.
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P N, Ojha, Suresh Kumar, Brijesh Singh, and Mohapatra B N. "Pervious concrete, plastic concrete and controlled low strength material- a special applications concrete." Journal of Building Materials and Structures 7, no. 2 (December 7, 2020): 221–35. http://dx.doi.org/10.34118/jbms.v7i2.777.
Повний текст джерелаАнотація:
The paper presents the study carried out for three special concretes like Pervious Concrete, Plastic Concrete and Controlled Low Strength Materials (CLSM) using locally available materials. Pervious concrete is a concrete with high porosity. It is used in a wide range of applications including pervious pavements and helps in improving pavement skid resistance and reducing hydroplaning. This concrete was designed to meet the requirement of 28-day compressive strength of 10 MPa and water permeability of 0.50 cm/sec. Plastic concrete has low compressive strength but higher ductility and lower permeability. It is used for creating an impermeable barrier (cut-off wall) for containment of contaminated sites or seepage control in highly permeable dam foundations. This concrete was designed to meet the requirement of 28-day unconfined compressive strength of 1.5 to 2.5 MPa and confined compressive strength of 2.5 to 3.5 Mpa at confining pressure of 4 Kg/cm2. Controlled Low Strength Material (CLSM) or flowable fill mixtures are typically specified and used in place of compacted fill especially for backfill, utility bedding, void fill and bridge approaches. CLSM is a self-compacting, flowable, low strength cementitious material which suits the requirement of different applications such as excavatable backfill and structural backfill. The properties of CLSM that were investigated included bleeding, density of hardened CLSM, permeability and unconfined compressive strength at 7 days and 28 days age.
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Mansori, Mohamed El, and Barney E. Klamecki. "Magnetic Field Effects in Machining Processes and on Manufactured Part Mechanical Characteristics." Journal of Manufacturing Science and Engineering 128, no. 1 (July 20, 2005): 136–45. http://dx.doi.org/10.1115/1.2113007.
Повний текст джерелаАнотація:
A review of research results demonstrating that magnetic fields applied to machining processes and mechanically manufactured parts can have beneficial effects is presented, an explanatory mechanistic model is described, and the model is used to interpret some results. The magnetic field-material interaction model shows an exponential dependence of material behavior and mechanical property changes on applied field strength and material magnetostrictive characteristics. Implications for use of magnetic fields to manipulate tribological processes, control machining processes, and alter material properties are that low field strengths can be useful for treating materials that have large magnetostrictive stain and high magnetic saturation level.
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Sun, Jing, Jing Shun Yuan, Xiao Hong Cong, and Hong Bo Liu. "Experimental Study on Quality Control of Moderate-Strength Commercial Concrete." Applied Mechanics and Materials 174-177 (May 2012): 460–63. http://dx.doi.org/10.4028/www.scientific.net/amm.174-177.460.
Повний текст джерелаАнотація:
For the quality control of commercial concrete, it is important to choose correct raw- material and mixture ratio. C40 and C50 concrete were prepared in dry and cold climate environment, using local raw materials and a large amount of fly ash. Specific researches were made about different kinds and dosage of superplasticizers on the slump of concrete, slump loss and the intensity of the impact. The results show that naphthalene series superplasticizer JK-2 and 30% of fly ash can ensure that slump of the mixture concrete reach more than 180mm, slump loss is less than 30mm in an hour, strength of hardened paste will not be reduced, and concrete can be prepared with low costs.
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Saithongkum, Nathathai, and Karuna Tuchinda. "Study of Properties of 3D Printed Short Carbon Fiber Composite." Key Engineering Materials 841 (May 2020): 182–87. http://dx.doi.org/10.4028/www.scientific.net/kem.841.182.
Повний текст джерелаАнотація:
The properties of composite materials do not depend only on the properties of raw materials but also other parameters such as volume fraction, geometry, dimension and material distribution etc. Carbon fiber reinforced polymer is one of the top choices of composite material because carbon fiber has light weigh with high tensile strength. For fiber-based composite such as carbon fiber composite, directions of carbon fiber with respect to loading direction could also affect to the strength of composite material under load. In this work, the properties of short carbon fiber-resin composite were investigated (fiber length of 0.2 mm.) with two different fiber orientations, i.e. 0 and 90 degrees to applied load. The 3D printing technique was employed in order to control carbon fiber direction and minimize material loss leading to material cost reduction. It was found that 3D printing technique could control direction of fiber in most case. However, at area with high curvature, the unexpected fiber direction was observed due to post hot process during which material flow was expected. It should also be noted that fiber path during 3D printing process may be very crucial as it could result in low strength local area due to low fiber density. This area could promote stress concentration leading to final fracture.
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Bodek, Sophie, and Douglas J. Jerolmack. "Breaking down chipping and fragmentation in sediment transport: the control of material strength." Earth Surface Dynamics 9, no. 6 (December 6, 2021): 1531–43. http://dx.doi.org/10.5194/esurf-9-1531-2021.
Повний текст джерелаАнотація:
Abstract. As rocks are transported, they primarily undergo two breakdown mechanisms: fragmentation and chipping. Fragmentation is catastrophic breakup by fracture in the bulk – either by subcritical crack growth under repeated collisions, or from a single high-energy (supercritical) collision – and produces angular shards. Chipping is a distinct low-energy mechanism of impact attrition that involves shallow cracking; this process rounds river pebbles in a universal manner under bed-load transport. Despite its geophysical significance, the transition from chipping to fragmentation is not well studied. Here, we examine this transition experimentally by measuring the shape and mass evolution of concrete particles of varying strength, subject to repeated collisions in a rotating drum. For sufficiently strong particles, chipping occurred and was characterized by the following: attrition products were orders of magnitude smaller than the parent; attrition rate was insensitive to material strength; and particles experienced monotonic rounding toward a spherical shape. As strength decreased, we observed the onset of a subcritical cracking regime associated with fragmentation: mass of attrition products became larger and more varied; attrition rate was inversely proportional to material strength; and shape evolution fluctuated and became non-monotonic. Our results validate conceptual and numerical models for impact attrition: chipping follows “Sternberg's law” of exponential mass loss through time; for fragmentation, the lifetime of particles increases nonlinearly with material strength, consistent with “Basquin's law” of fatigue failure. We suggest that bedrock erosion models must be clarified to incorporate distinct attrition mechanisms, and that pebble or bedrock-channel shape may be utilized to deduce the operative mechanism in a given environment.
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Solikin, Mochamad. "Compressive Strength Development of High Strength High Volume Fly Ash Concrete by Using Local Material." Materials Science Forum 872 (September 2016): 271–75. http://dx.doi.org/10.4028/www.scientific.net/msf.872.271.
Повний текст джерелаАнотація:
This paper presents a research to produce high strength concrete incorporated with fly ash as cement replacement up to 50% (high volume fly ash concrete) by using local material. The research is conducted by testing the strength development of high volume fly ash concrete at the age of 14 days, 28 days and 56 days. As a control mix, the compressive strength of Ordinary Portland Cement (OPC) concrete without fly ash is used. Both concrete mixtures use low w/c. consequently, they lead to the use of 1 % superplasticizer to reach sufficient workability in the process of casting. The specimens are concrete cubes with the dimension of 15 cm x15 cm x 15 cm. The totals of 24 cubes of HVFA concrete and OPC concrete are used as specimens of testing. The compressive strength design of concrete is 45 MPa and the slump design is ± 10 cm. The result shows that the compressive strengths of OPC concrete at the age of 14 days, 28 days, and 56 days are 38 MPa, 40 MPa, and 42 MPa. Whereas the compressive strength of HVFA concrete in the same age of immersing sequence are 29 MPa, 39 MPa, and 42 MPa. The result indicates that HVFA concrete can reach the similar compressive strength as that of normal concrete especially at the age of 56 days by deploying low water cement ratio.
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Peterside, David T., Joseph E. Palaia, Andrew C. Schuerger, Melanie J. Correll, and Ray A. Bucklin. "Testing of Greenhouse Cladding Materials for Space Environments, Part 2: Laminates." Applied Engineering in Agriculture 34, no. 3 (2018): 575–80. http://dx.doi.org/10.13031/aea.12465.
Повний текст джерелаАнотація:
Abstract. Plants grown in greenhouse-type structures are potential sources of food, oxygen, clean water, fiber, and other resources needed for bioregenerative life support systems during long-term space missions. Identification of cladding materials with appropriate optical and physical properties that can withstand the high ultraviolet radiation, low pressure, and low temperature Martian environment is necessary for greenhouse design. The objective of this study was to evaluate the effects of simulated Mars environmental conditions on yield strength and light transmissivity of composites composed of a layer of 0.15 mm polyimide film (LaRC™CP1) attached to acrylic, polyvinyl chloride (PVC), or polycarbonate cladding materials. The University of Florida’s Mars Simulation Chamber (MSC) at Kennedy Space Center was utilized to expose material samples to simulated Mars environmental conditions. Changes in control versus exposed material sample transmissivities were measured using a spectroradiometer over the PAR range of wavelengths from 400 to 700 nm and material peak yield strengths were determined using an Instron universal testing machine. Keywords: LaRC™CP1, Mars greenhouse, PAR transmission, Plastics, Strength of materials, UV damage.The overall results comparing pre- and post-exposure of samples to simulated Martian conditions in the MSC showed that the addition of a layer of polyimide did not benefit either the transmissivity or strength of polycarbonate cladding materials, but did show benefits in retaining transmissivity for PVC and in maintaining strength for acrylics exposed to Mars simulated environment. However, transmissivities of the plastics were reduced by the addition of protective layers of polyimide. Keywords: LaRC™CP1, Mars greenhouse, PAR transmission, Plastics, Strength of materials, UV damage.
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Cooper, Khershed P. "Manufacturing Technologies for Small Lot Size, Short Cycle Time and Low Cost." Materials Science Forum 561-565 (October 2007): 821–26. http://dx.doi.org/10.4028/www.scientific.net/msf.561-565.821.
Повний текст джерелаАнотація:
New manufacturing methods involving direct fabrication processes seem ideal for mass customization or “just-in-time” production. The use of tool-less means of production ensures reduced lead-time and lower cost. Besides, they provide flexibility in design and fabrication, which are essential for small lot sizes. However, part quality and production reliability are challenges that must be met. When adapted to the micro-factory paradigm, direct manufacturing can be made portable and capable of remote manufacturing. The benefits of miniaturization are savings in materials and energy consumption, but the increased surface area to volume ratio has implications for material behavior, especially mechanical strength. The newest incarnation of direct manufacturing is direct digital manufacturing or DDM, which involves localized deposition of material or energy and the creation of heterogeneous objects with digital means of control. DDM seeks spatial control of macrostructure, composition, texture and properties with the possibility of producing materials with unusual behavior, functionally gradient structures and integrated component devices. For DDM, multi-material design, precision in deposition, shaping and removal and understanding of heterogeneous material behavior are challenges.
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Batog, Andrzej, and Elżbieta Stilger-Szydło. "Low-Strength Substrates and Anthropogenic Soils in Transportation Engineering." Studia Geotechnica et Mechanica 40, no. 4 (December 26, 2018): 292–99. http://dx.doi.org/10.2478/sgem-2018-0029.
Повний текст джерелаАнотація:
AbstractRoad embankments, especially their slopes’ surfaces, must fulfil all the requirements concerning the exploitation criteria after the completion of construction works. This is very important while constructing or modernizing the embankments, based on the substrate including low-strength soils as well as in simple ground conditions (most convenient). The last dozen or so years of intensive construction of transport infrastructure have shown how big is the problem of ensuring the required volumes of qualified soil material for the construction of road embankments or the modernization of railway embankments. The depleting deposits of natural and easily accessible soils for the construction of embankments result in the need to use anthropogenic soils, for example, in the form of aggregates from the recycling of construction waste and other locally available waste materials, usually in the form of slag and ashes from the combined heat and power plants. In such cases, there’s a need to treat transportation earth structures individually in the scope of designing and quality control, because there are no applicable standard provisions in this scope.This work indicates some of these important contemporary problems of transport engineering, occurring in newly built and modernized road objects, such as the stability of road embankments based on a low-strength substrate, use of anthropogenic soils and materials originating from the recycling of concrete surfaces for the construction of road embankments.
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Panda, Biranchi, Nisar Ahamed Noor Mohamed, Suvash Chandra Paul, GVP Bhagath Singh, Ming Jen Tan, and Branko Šavija. "The Effect of Material Fresh Properties and Process Parameters on Buildability and Interlayer Adhesion of 3D Printed Concrete." Materials 12, no. 13 (July 4, 2019): 2149. http://dx.doi.org/10.3390/ma12132149.
Повний текст джерелаАнотація:
The advent of digital concrete fabrication calls for advancing our understanding of the interaction of 3D printing with material rheology and print parameters, in addition to developing new measurement and control techniques. Thixotropy is the main challenge associated with printable material, which offers high yield strength and low viscosity. The higher the thixotropy, the better the shape stability and the higher buildability. However, exceeding a minimum value of thixotropy can cause high extrusion pressure and poor interface bond strength if the printing parameters are not optimized to the part design. This paper aims to investigate the effects of both material and process parameters on the buildability and inter-layer adhesion properties of 3D printed cementitious materials, produced with different thixotropy and print head standoff distances. Nano particles are used to increase the thixotropy and, in this context, a lower standoff distance is found to be useful for improving the bond strength. The low viscosity “control” sample is unaffected by the variation in standoff distances, which is attributed to its flowability and low yield stress characteristics that lead to strong interfacial bonding. This is supported by our microscopic observations.
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Par, Matej, Laura Plančak, Lucija Ratkovski, Tobias T. Tauböck, Danijela Marovic, Thomas Attin, and Zrinka Tarle. "Improved Flexural Properties of Experimental Resin Composites Functionalized with a Customized Low-Sodium Bioactive Glass." Polymers 14, no. 20 (October 12, 2022): 4289. http://dx.doi.org/10.3390/polym14204289.
Повний текст джерелаАнотація:
This study evaluated the flexural properties of an experimental composite series functionalized with 5–40 wt% of a low-Na F-containing bioactive glass (F-series) and compared it to another experimental composite series containing the same amounts of the conventional bioactive glass 45S5 (C-series). Flexural strength and modulus were evaluated using a three-point bending test. Degree of conversion was measured using Fourier-transform infrared spectroscopy. Weibull analysis was performed to evaluate material reliability. The control material with 0 wt% of bioactive glass demonstrated flexural strength values of 105.1–126.8 MPa). In the C-series, flexural strength ranged between 17.1 and 121.5 MPa and was considerably more diminished by the increasing amounts of bioactive glass than flexural strength in the F-series (83.8–130.2 MPa). Analogously, flexural modulus in the C-series (0.56–6.66 GPa) was more reduced by the increase in bioactive glass amount than in the F-series (5.24–7.56 GPa). The ISO-recommended “minimum acceptable” flexural strength for restorative resin composites of 80 MPa was achieved for all materials in the F-series, while in the C-series, the materials with higher bioactive glass amounts (20 and 40 wt%) failed to meet the requirement of 80 MPa. The degree of conversion in the F-series was statistically similar or higher compared to that of the control composite with no bioactive glass, while the C-series showed a declining degree of conversion with increasing bioactive glass amounts. In summary, the negative effect of the addition of bioactive glass on mechanical properties was notably less pronounced for the customized bioactive glass than for the bioactive glass 45S5; additionally, mechanical properties of the composites functionalized with the customized bioactive glass were significantly less diminished by artificial aging. Hence, the customized bioactive glass investigated in the present study represents a promising candidate for functionalizing ion-releasing resin composites.
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Wang, H., and T. Vu-Khanh. "Damage Extension in Carbon Fiber/PEEK Crossply Laminates under Low Velocity Impact." Journal of Composite Materials 28, no. 8 (May 1994): 684–707. http://dx.doi.org/10.1177/002199839402800801.
Повний текст джерелаАнотація:
Low-velocity impact in carbon fiber/PEEK crossply laminates has been studied by test and analysis. Emphases of the study were focused on the material properties which may control the damage extension of transverse crack and delamination. It was found that, considering the thermal residual stress and the crack constraining effect, extension of transverse cracks could not be predicted by the Strength of Materials approach. The impact-induced delamination could be characterized by the crack arrest concept of fracture mechanics. The delamination resulted from a Mode II-dominated unstable fracture, which occurred under displacement-controlled conditions and seemed to be arrested at a constant interlaminar fracture energy. It was found that the thermoplastic APC-2 composite exhibits the same damage modes as epoxy composites under low velocity impact. Both the matrix-controlled damage and the fiber-controlled penetration may become the dominant failure mode, depending on the stacking sequence of the laminate. The residual stress in the thermoplastic laminates is as high as half of the transverse strength of the unidirectional material. The crack constraining effect tends to increase the in situ transverse strength of the lamina as the lamina thickness decreases. Considering the residual stress and crack constraining effect, the transverse crack extension cannot be predicted by the Strength of Materials approach. The crack arrest concept of fracture mechanics seems to be a useful approach to predict the extension of impact-induced delamination. The delamination resulted from a Mode II-dominated unstable fracture, which occurred under displacement-controlled conditions and seemed to be arrested at a constant interlaminar fracture energy. By assuming the delamination arrest at about the time of maximum impact load, the delamination arrest toughness could be evaluated from the test data of [05/905/05] laminates. The delamination arrest toughness is also found to be close to the Mode II-propagation toughness of the material.
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Yang, Dao Yuan, and Guang Hui Wei. "Research the Performance of Alumina Insulation Material by Freeze-Drying." Key Engineering Materials 512-515 (June 2012): 527–30. http://dx.doi.org/10.4028/www.scientific.net/kem.512-515.527.
Повний текст джерелаАнотація:
The traditional method of preparation alumina insulation material includes the addition of pore-forming agent, direct foaming, foam impregnation and gel-casting. In this experiment, α-alumina as raw material, silica fume as an additive, Combination freeze-drying method, add pore-forming agent and direct foaming successfully prepared low-density, high strength, low thermal conductivity of alumina insulation material. Change the particle size of pore-forming agent can be get different properties of the sample. The SEM photograph was clearly observed that the hole wall dense uniform, α-alumina particles sufficient contact, no significant ice sublimation hole left. There are also the reasons of the sample with higher value of bending strength and compressive strength. This can make a control of porosity, as well as pore size, pore shape and pores space topology of alumina insulation material.
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He, Long, Jin Shi Li, Mei Hua Chen, Yan Yang, Xin Peng Lou, Mao Lin Chen, Jie Guang Song, Lin Chen, Song Lin Guo, and Cheng Wei Hao. "Effect of Control Technology on Properties of Quartz Porous Brick." Key Engineering Materials 777 (August 2018): 564–68. http://dx.doi.org/10.4028/www.scientific.net/kem.777.564.
Повний текст джерелаАнотація:
A high-performance quartz sand insulation brick was prepared by using low grade quartz sand under different sintering process conditions. The optimum sintering process conditions were obtained by analyzing the relationship between microstructure and sintering process. Through the compounding, pulping, forming, drying and sintering processes, and the performance test of the porous brick, the following conclusions can be drawn, the comprehensive performance in all aspects, the porosity is similar, the preferred high compressive strength conditions, in order to get a best The bonding point, brick body sintering temperature of 1150 °C, porosity of 74.56%, compressive strength of 2.1 MPa of porous brick, and the pores are smooth, more uniform distribution. With the prolonging of the holding time, the porosity of the porous brick is reduced, and the performance is 1h, the porosity is 77.22% and the compressive strength is 2.05 MPa. When the raw material ratio is 60% quartz sand, 30wt% kaolin, calcium carbonate 9.6wt%, foaming agent 0.4wt%, water ratio 0.9 holding time at 1h sintering at 1150°C can get better porosity and compressive strength of the insulation brick. The porous material was sintered at 1150 °C, the content of foaming agent was 0.2wt%, the ratio of water to material was 0.9, and the compressive pressure and porosity were the better.
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Dahar, Eddy, and Raudhatul Husna. "PENGARUH PENAMBAHAN ZIRKONIUM OKSIDA DAN SERAT POLIPROPILEN TERHADAP KEKUATAN IMPAK DAN TRANSVERSAL BAHAN BASIS GIGI TIRUAN RESIN AKRILIK POLIMERISASI PANAS." Jurnal Ilmiah PANNMED (Pharmacist, Analyst, Nurse, Nutrition, Midwivery, Environment, Dentist) 12, no. 2 (October 19, 2018): 177–82. http://dx.doi.org/10.36911/pannmed.v12i2.21.
Повний текст джерелаАнотація:
Heat polymerized acrylic resin is the most common material used for making denture base because of it’s advantages. However, this material still hasn’t fulfill all the ideal requirements as a denture base. Some disadvantages that need to be fixed are low impact and transverse strength causing an easy base of fracture. Several attempts were made to improve the mechanical properties of heat polymerized acrylic resin materials by adding reinforcing materials. Zirconium oxide is one of chemical group that can be used as a reinforcing material and polypropylene fiber which is including in fiber reinforcing groups. This study aims to determine whether there is a difference in the effect of the addition of 5% ZrO2 nanoparticles and 2% chopped polypropylene fibers 6 mm in length on the impact and transverse strength of heat polymerized acrylic resin denture base material. The design of this study is a laboratory experimental and the number of samples in this study are 60 samples. The result of this study shows the mean value of the impact and transverse strength of heat polymerized acrylic resin with ZrO2 nanoparticles reinforced is greater than the control group and heat polymerized acrylic resin group with polypropylene fiber reinforced with significant difference, and the mean value of impact and transverse strength of heat polymerized acrylic resin with polypropylene fibers reinforced is greater than the control group with significant difference.
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Etxeberria, Miren, Javier Ainchil, Ma Eugenia Pérez, and Alain González. "Use of recycled fine aggregates for Control Low Strength Materials (CLSMs) production." Construction and Building Materials 44 (July 2013): 142–48. http://dx.doi.org/10.1016/j.conbuildmat.2013.02.059.
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Berglund, Lars A., and Ton Peijs. "Cellulose Biocomposites—From Bulk Moldings to Nanostructured Systems." MRS Bulletin 35, no. 3 (March 2010): 201–7. http://dx.doi.org/10.1557/mrs2010.652.
Повний текст джерелаАнотація:
AbstractCellulose biocomposites are widely used in industry as a low-cost engineering material with plant fiber reinforcement. However, chemical and microstructural heterogeneity causes low strength, low strain-to-failure, high moisture sensitivity, and odor and discoloration problems. Efforts toward improved performance through fiber orientation control, increased fiber lengths, and biopolymer use are reviewed. Interfacial strength control and moisture sensitivity are remaining challenges. As an attractive alternative reinforcement, high-quality cellulose nanofibers obtained by wood pulp fiber disintegration can be prepared at low cost. These nanofibers have high length/diameter ratios, diameters in the 5–15 nm range, and intrinsically superior physical properties. Wood cellulose nanofibers are interesting as an alternative reinforcement to more expensive nanoparticles, such as carbon nanotubes. Nanopaper and polymer matrix nanocomposites based on cellulose nanofiber networks show high strength, high work-of-fracture, low moisture adsorption, low thermal expansion, high thermal stability, high thermal conductivity, exceptional barrier properties, and high optical transparency. The favorable mechanical performance of bioinspired foams and low-density aerogels is reviewed. Future applications of cellulose biocomposites will be extended from the high-volume/low-cost end toward high-tech applications, where cellulose properties are fully exploited in nanostructured materials.
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Sarcev, Branislava Petronijevic, Danka Labus Zlatanovic, Miroslav Hadnadjev, Branka Pilic, Ivan Sarcev, Dubravka Markovic, and Sebastian Balos. "Mechanical and Rheological Properties of Flowable Resin Composites Modified with Low Addition of Hydrophilic and Hydrophobic TiO2 Nanoparticles." Materiale Plastice 58, no. 2 (July 5, 2021): 80–90. http://dx.doi.org/10.37358/mp.21.2.5480.
Повний текст джерелаАнотація:
The aim of this work was to find the influence of the addition of low amount of hydrophilic and hydrophobic TiO2 nanoparticles on compressive strength, microhardness and rheological properties of flowable dental composite material. Specimens were prepared by adding 0.05; 0.2 and 1 wt. % of hydrophilic and hydrophobic 20 nm TiO2 nanoparticles. These specimens were compared to non-modified control specimens in compressive strength and microhardness. Furthermore, their rheological properties were determined. The optimal nanoparticle loading was 0.2 % hydrophobic TiO2, resulting in significantly higher compressive strength and microhardness than those of the control specimen group. Mechanical properties of flowable composites reinforced with hydrophilic and hydrophobic TiO2 at higher loadings are lower than those of control specimens, which is the result of nanoparticle agglomeration. TiO2 nanoparticles addition resulted in the decrease in viscosity in all specimens except for the specimewn with 1% hydrophilic TiO2 nanoparticles. In accordance to the obtained results, hydrophobic nanoparticle addition results in a more resistant and durable material, combined with an increased flowability compared to a non-modified composite.
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Meng, Qingyu. "Numerical Simulation of Multifunctional Projectile Penetrating Reinforced Concrete Target Plate Based on Sensor Data Acquisition." Journal of Sensors 2022 (August 31, 2022): 1–9. http://dx.doi.org/10.1155/2022/3115123.
Повний текст джерелаАнотація:
The main material of a type of multifunctional warhead is energy-containing material, which mainly relies on the projectile’s own kinetic energy to hit the target plate to achieve the function of penetrating reinforced concrete, so it needs the bullet material to have high strength and be able to withstand the high overload when penetrating reinforced concrete. At present, the composite energy-containing material structure with Al, Zr, Ti, and other materials as PTFE-based reducing agents is the mainstream direction of research on high-strength energy-containing materials. LS-DYNA is used to establish a simulation model to simulate and analyze the tapping power. The relationship curve between material strength and attack depth is established and compared with the experimental data of traditional steel material attack ammunition to finally determine the strength limit of energy-containing material compared with traditional attack ammunition. The simulation results show that the composite energy-containing material multifunctional projectile can accomplish the tapping task of penetrating 1.2 m reinforced concrete under the premise of ensuring that the percentage of W powder is not higher than 80%. This study has a certain reference value for the selection of energy-containing materials for multifunctional warheads. For the low-velocity penetration below 400 m/s, the effect of frictional resistance of the head as well as the sidewall on the penetration depth can be ignored, but the overload curve when considering the sidewall friction is more realistic. Using a combination of experimental and theoretical methods, the influence of the projectile material on the mass erosion of high-speed kinetic energy projectiles was studied, and the Jones erosion model based on the thermal melting principle was improved. Based on the cavity expansion theory, the calculation method of the shape evolution of the bullet head was established. The comparison with the experimental results shows that the improved model is applicable to different types of soft and hard materials and can accurately calculate the mass erosion amount, erosion depth, and shape evolution of the bullet head.
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Semboshi, Satoshi. "Guiding principles for creating new high strength-high conductivity copper alloys." Impact 2020, no. 1 (February 27, 2020): 71–73. http://dx.doi.org/10.21820/23987073.2020.1.71.
Повний текст джерелаАнотація:
Solid solution strengthened alloys such as brass and bronze have been widely used as contact materials for energisation in a range of devices due to the fact that they are relatively low cost. In more recent times precipitation strengthened alloys such as copper-beryllium, copper-titanium and copper-nickel-silicon are used due to their excellent strength and conductivity. Yet, little headway has been made in the development of precipitation hardening copper alloys due to the difficulty associated with departing from existing alloy designs and structure control methods. One team of researchers is exploring the use of over-aged material instead of the conventional peak-aged material. This is because previous studies have suggested that wires of this type may have improved strength and conductivity. But there remain many unknowns. Associate Professor Satoshi Semboshi is a researcher based at the Institute for Materials Research, Tohoku University, Japan, who is seeking to shed light on these unknowns.
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Kang, J. K., Yong Keun Lee, Kwang Mahn Kim, and Kyoung Nam Kim. "Effect of Glass Filler Content on Hydrophilic Addition Silicone Impression Materials in Dentistry." Key Engineering Materials 284-286 (April 2005): 909–12. http://dx.doi.org/10.4028/www.scientific.net/kem.284-286.909.
Повний текст джерелаАнотація:
Dental impression materials are used to register or reproduce the form and relationship of the teeth and oral tissues. They should not be torn when removing from the wet mouth after setting. Nowadays, silica is widely used as filler to overcome the low mechanical strength of the dental impression materials. The purpose of this study was to synthesize high strength glass in the system of MgO-CaO-Al2O3-SiO2 and investigate its usefulness according to ISO standard after mixing with addition silicone. Commercial products, Contrast, Examix, Express, and Perfect-F were selected as control group. When the prepared glass filler was introduced in addition silicone impression material, tear strength was drastically increased significantly than that of the control group, keeping the consistency. All experimental groups showed higher tear stength than that of control groups. As the amount of filler content increases, tear strength was increased. Strain in compression, recovery from deformation, and linear dimensional change were satisfied the ISO standard either all the experimental or control groups. Therefore, calcium-substituted magnesium aluminosilicate glass in the system of 12.5MgO-17.5CaO-20Al2O3-50SiO2 is expected the useful filler in the light body of addition silicone impression materials.
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Hornbogen, Erhard. "Contribution of Electron Microscopy to Structural Materials." Proceedings, annual meeting, Electron Microscopy Society of America 48, no. 1 (August 12, 1990): 10–11. http://dx.doi.org/10.1017/s042482010017880x.
Повний текст джерелаАнотація:
Structural materials are expected to fulfil mechanical functions, for example in bridges, crank shafts, turbine blades, or medical implants. In use, high strength is aspired at low materials weight. The structure should be safe and the costs of the material, semi—finished products, or parts should be low. The term strength implies the resistance of a material against plastic deformation, as well as against propagation of cracks (i. e. toughness). Safety is connected with the control of various mechanisms of crack growth such as rupture, fatigue, and stress corrosion cracking. Finally, interaction of surfaces will induce a frictional shear stress, which may cause wear. The life of structures is usually limited by mechanical failure, which may become catastrophic, if it is unexpected due to lack of understanding of structural materials.The specific weight of materials predominantly stems from the kind of atoms from which the material is built. The properties implied in strength are mainly related to microstructure. There are only two types of phases of which materials are built: crystals and glasses (if the quasicrystals are neglected, for which applications have not yet been found). Metals are usually crystalline. Their strength is closely related to the properties of crystal dislocations. Transmission electron microscopy (TEM) is the major tool for their investigation. Resistance against plastic deformation (i. e. yield stress) is controlled by elements of the microstructure, which act as obstacles against their motion. These microstructural features and their interaction with dislocations can also be analysed by TEM. It is reasonable to classify microstructural objects according to their geometrical dimensions 0 ≤ d ≤ 3. They become hardening mechanisms which are the ways by which the yield strength (i. e. load carrying ability of a material canb be raised).
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Fu, Hong-Yuan, Shuang-Xing Qi, Zhen-Ning Shi, and Ling Zeng. "Mixing Ratios and Cementing Mechanism of Similar Silty Mudstone Materials for Model Tests." Advances in Civil Engineering 2021 (August 17, 2021): 1–19. http://dx.doi.org/10.1155/2021/2426130.
Повний текст джерелаАнотація:
The similarity model test is one of the important means to study the engineering properties of soft rock. This study aims to develop similar materials for silty mudstone, which has characteristics of low strength and water expansion, based on traditional materials including gypsum, barite powder, clay minerals, and distilled water. The orthogonal design method was used to determine the mixing ratios of the similar materials. The density, uniaxial compressive strength, tensile strength, elastic modulus, and Poisson’s ratio were selected as control indicators of the similar materials. The results show that the water content is the dominant factor for the density, tensile strength, elastic modulus, and Poisson’s ratio of the similar materials of silty mudstone, while the gypsum content is the dominant factor for the uniaxial compressive strength. The physical and mechanical properties of the similar material samples with water content of 19%, barite powder ratio of 32%, and gypsum mass of 250 g show good similarity to those of the raw silty mudstone. The water absorption and expansibility of similar materials with clay mineral ratio of 12% are consistent with those of the raw silty mudstone. The scanning electron microscopy (SEM) observation indicates that the similar material with optimal mixing ratios exhibits a similar microstructure to that of silty mudstone.
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Chukwudi, Obi Ifeanyi. "ORGANIC PLASTICS: MATERIAL FOR SICK BUILDING SYNDROME CONTROL AND PREVENTION IN BUILDING CONSTRUCTION." International Journal of Research -GRANTHAALAYAH 6, no. 6 (June 30, 2018): 193–99. http://dx.doi.org/10.29121/granthaalayah.v6.i6.2018.1365.
Повний текст джерелаАнотація:
Plastics are organic materials, which consist of synthetic or natural high-molecular compounds (polymers). Due to the large variety of plastic, its different types have different properties, which make it possible to widely use this material in all fields of industry from packaging to the construction industry. The second highest consumer of organic plastics materials after packaging is the construction industry. Thanks to great versatility, cost effectiveness, durability, strength to weight ratio and low maintenance plastics appear to be economically attractive in the construction sector and are used in the manufacturing of wide range of materials in the construction industry. Plastics most times are not easily seen in buildings, but they are widely used in construction and building industry for a vast and wide range of materials, which include insulation, piping, interior design, piping and conduit (rain water, electrical conduits, and sewage pipes, gas distributions and plumbing). Piping and Conduit for instance can consume around 35% of plastic production and are one of the largest consumers of polymers in construction. The purpose of this research is to study plastic as a construction material that can be used to control the formation of Sick building syndrome in buildings, and also as a material that can often be used in the construction industry.
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Oguntuase, Musa, Gbenga Joshua Adeyemi, and Joseph Temitope Stephen. "Effects of Cow Horn Particulates as Addictive on Microstructure, Tensile and Compressive Properties of Recycled Aluminium Alloy." European Journal of Engineering and Technology Research 7, no. 2 (April 29, 2022): 146–52. http://dx.doi.org/10.24018/ejeng.2022.7.2.2803.
Повний текст джерелаАнотація:
In the recent time, the development of low cost metal alloys reinforced with waste materials such as agricultural waste and industrial waste has been one of the major innovations in the area of material science. Aluminium scraps were used as raw material and reinforced with locally available inexpensive cow horn particulate (CHp) of 3, 6, 9 and 12% by weight to develop a new material in the present study. The microstructure view was studied using optical microscope for analysing the distribution of CHp. The tensile and compressive strengths were studied for the reinforced CHp aluminium alloy. The results revealed that the tensile and compressive strengths values increase as the CHp increases and falls when the weight proportion reaches 12% due to poor wettability. Increment of 10.1%, 19.2%, 29.4% and 8.7% in tensile strength and 13.3%, 31.2%, 43.2% and 12.7% in the compressive strength were recorded for addition of 3%, 6%, 9% and 12% CHp reinforcement, respectively. The microstructure examination shows that the control sample contained fine, packed and shining grained structure while the CHp reinforced aluminium alloy contained less packed, dull with some inclusion grained structure. The inclusion and dull surface of the grains was observed increases as the percentages of the cow horn particles added increased. The spectrographic analysis conducted to determine the chemical compositions of all the specimens, showed various elements present in control sample and CHp reinforced aluminium alloy. Aluminium is in the range 91.3-93.0%, followed by silicon with 4.36-5.01%, other elements present include iron, copper, magnesium, manganese, chromium, nickel, zinc, titanium, lead, and others.
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Santini, Silvia, Angelo Forte, and Lorena Sguerri. "The Structural Diagnosis of Existing RC Buildings: The Role of Nondestructive Tests in the Case of Low Concrete Strength." Infrastructures 5, no. 11 (November 12, 2020): 100. http://dx.doi.org/10.3390/infrastructures5110100.
Повний текст джерелаАнотація:
In the structural safety assessment process of existing structures, knowledge of the mechanical properties of the materials is key. Different experimental activities carried out on materials extracted from existing reinforced concrete buildings show a high strength variability, especially concrete. In the past, the lack of standardized quality control for materials and workmanship caused nonuniform and homogeneous properties within the same structure. The most accurate and reliable experimental technique consists of performing direct tests on the materials, but these are considerably expensive and invasive. In this paper, alternative indirect methods that estimate material properties by correlating different physical measures were proved to reduce invasive inspections on existing buildings and infrastructures, especially in built heritage. A complete experimental activity concerning destructive and nondestructive tests was conducted on elements (four portions of a column and a beam portion) removed from an Italian school building built in 1940. Destructive and nondestructive methods were compared and appropriate correlation laws developed to predict the main mechanical properties of the studied material. Reliable correlations were identified considering the pull-out test, Sonic–Rebound (SonReb) combined method and ultrasonic pulse velocities (UPVs). The latter were mapped by tomography, which highlighted the compression properties of concrete in the different structural sections.
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Gomez-Rivas, E., A. Griera, and M. G. Llorens. "Fracturing of ductile anisotropic multilayers: influence of material strength." Solid Earth Discussions 7, no. 1 (January 29, 2015): 419–57. http://dx.doi.org/10.5194/sed-7-419-2015.
Повний текст джерелаАнотація:
Abstract. Fractures in rocks deformed under dominant ductile conditions typically form simultaneously with viscous flow. Material strength plays a fundamental role on fracture development in such cases, since fracture propagation can be strongly reduced by the high energy absorption of the material. Additionally, the degree and nature of anisotropy can influence the orientation and type of resulting fractures. In this study, four plasticine multilayer models have been deformed under coaxial boundary conditions to investigate the influence of strength and anisotropy on the formation of fracture networks. The experiments were made of different mixtures and presented two types of anisotropy: composite and composite-intrinsic. The transition from non-localised deformation to systems where fracture networks control deformation accommodation is determined by the ability of the material to dissipate the external work and relax the elastic strain during loading, either by viscous flow or by coeval flow and failure. Tension cracks grow in experiments with composite anisotropy, giving rise to a network of shear fractures when they collapse and coalesce with progressive deformation. The presence of an additional intrinsic anisotropy enhances the direct nucleation of shear fractures, whose propagation and final length depend on the rigidity of the medium. Material strength increases the fracture maximum displacement (dmax) to fracture length (L) ratio, and the resulting values are significantly higher than those from fractures in elastic-brittle rocks. This is associated with the low propagation rates of fractures in rocks undergoing ductile deformation.
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Gomez-Rivas, E., A. Griera, and M. G. Llorens. "Fracturing of ductile anisotropic multilayers: influence of material strength." Solid Earth 6, no. 2 (May 19, 2015): 497–514. http://dx.doi.org/10.5194/se-6-497-2015.
Повний текст джерелаАнотація:
Abstract. Fractures in rocks deformed under dominant ductile conditions typically form simultaneously with viscous flow. Material strength plays a fundamental role during fracture development in such systems, since fracture propagation can be strongly reduced if the material accommodates most of the deformation by viscous flow. Additionally, the degree and nature of anisotropy can influence the orientation and type of resulting fractures. In this study, four plasticine multilayer models have been deformed under coaxial boundary conditions to investigate the influence of strength and anisotropy on the formation of fracture networks. The experiments were made of different mixtures and had two types of anisotropy: composite and composite-intrinsic. The transition from non-localised deformation to systems where fracture networks control deformation accommodation is determined by the ability of the material to dissipate the external work and relax the elastic strain during loading either by viscous flow or by coeval flow and failure. Tension cracks grow in experiments with composite anisotropy, giving rise to a network of shear fractures when they collapse and coalesce with progressive deformation. The presence of an additional intrinsic anisotropy enhances the direct nucleation of shear fractures, the propagation and final length of which depend on the rigidity of the medium. Material strength increases the fracture maximum displacement (dmax) to fracture length (L) ratio, and the resulting values are significantly higher than those from fractures in elastic–brittle rocks. This can be related to the low propagation rates of fractures in rocks undergoing ductile deformation.
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Fang, Jun, Shi Qiang Lu, Chuang Liang, and Xu Guang Min. "Springback Behavior of High Strength Titanium Tube after Bending under Variations of Material Property Parameters." Key Engineering Materials 881 (April 2021): 13–18. http://dx.doi.org/10.4028/www.scientific.net/kem.881.13.
Повний текст джерелаАнотація:
In order to reveal the springback behavior of high strength TA18 tube after numerical control (NC) bending under the variations of material property parameters, the finite element (FE) model of the whole process for the high strength TA18 tube during NC bending was established under ABAQUS code and its stability was evaluated. Then, using the model, the springback behavior after tube bending under the variations of material property parameters was studied, and the significance of material property parameters on springback was revealed. The results show that the springback angle decreases with the increase of the Young’s modulus, hardening exponent and thickness anisotropy exponent or with the decrease of the strength coefficient and yield stress. The significance of material property parameters on springback of the high strength TA18 tube after NC bending from high to low are the yield stress, Young’s modulus, strength coefficient, thickness anisotropy exponent and hardening exponent.
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Liu, Hongtao, Yang Chen, Zijun Han, Qinyu Liu, Zilong Luo, Wencong Cheng, Hongkai Zhang, Shizhu Qiu, and Haozhu Wang. "Coal Wall Spalling Mechanism and Grouting Reinforcement Technology of Large Mining Height Working Face." Sensors 22, no. 22 (November 10, 2022): 8675. http://dx.doi.org/10.3390/s22228675.
Повний текст джерелаАнотація:
To control the problem of coal wall spalling in large mining height working faces subject to mining, considering the Duanwang Mine 150505 fully mechanized working face, the mechanism of coal wall spalling in working faces was investigated by theoretical analysis, numerical simulation and field experiment. Based on analysis of coal wall spalling in the working face, a new grouting material was developed. The stress and plastic zone changes affecting the coal wall, before and after grouting in the working face, were analyzed using numerical simulation and surrounding rock grouting reinforcement technology was proposed for application around the new grouting material. The results showed that: (1) serious spalling of the 150505 working face was caused by the large mining height, fault influence and low roof strength, and (2) the new nano-composite low temperature polymer materials used have characteristics of rapid reaction, low polymerization temperature, adjustable setting time, high strength and environmental protection. Based on analysis of the working face coal wall spalling problem, grouting reinforcement technology based on new materials was proposed. Industrial tests were carried out on the working face. Field monitoring showed that the stability of the working face coal wall was significantly enhanced and that rib spalling was significantly improved after comprehensive anti-rib-spalling grouting measures were adopted. These results provide a basis for rib spalling control of working faces under similar conditions.
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Han, Xiao Ming, and Er Bu Shen. "The Technique of Single-Component Synchronous Grouting Allocation to Resist Floating in High Pressure Water-Rich Formation." Key Engineering Materials 889 (June 16, 2021): 171–76. http://dx.doi.org/10.4028/www.scientific.net/kem.889.171.
Повний текст джерелаАнотація:
In high pressure water-rich formation, the grout is diluted by groundwater, could not develop early strength as quickly as possible for the dissipation of cementing material, failed to fill effectively the space between the segment and formation, which is unhelpful to control segment floating. In this study, by adding a variety of organic and inorganic materials to reduce grout setting time, meanwhile ensure the low loss of fluidity, high anti-aqueous dispersions, low shrinkage, finally, to achieved better effect than Two-component grouting.
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Galimzyanova, Rezeda Yu, Maria S. Lisanevich, and Yuri N. Khakimullin. "Influence of Gamma and Electron Radiation on the Strength Characteristics of Nonwoven SMS Materials Based on Polypropylene." Key Engineering Materials 899 (September 8, 2021): 172–78. http://dx.doi.org/10.4028/www.scientific.net/kem.899.172.
Повний текст джерелаАнотація:
Radiation sterilization is widely used to sterilize nonwoven SMS medical products. SMS materials have improved filtering and barrier properties, low bacteriopermeability and, due to these properties, are indispensable for medicine. They are used to make such important health care products as disposable surgical clothing and underwear. As a result of the research carried out, the effect of gamma and electron radiation, in the range of absorbed doses from 15 to 25 kGy, on the strength characteristics of nonwoven SMS materials based on polypropylene with a surface density of 35, 40, 50 g/cm2 was studied. It has been established that the strength characteristics (tensile strength, tensile strength, and tear strength) of nonwoven materials decrease after exposure to ionizing radiation. The higher the density of the material, the more its characteristics decrease after radiation sterilization. It was also found that gamma radiation, due to its nature, has a stronger effect on nonwoven materials based on polypropylene, and leads to a stronger decrease in strength characteristics. In general, for products sterilized by ionizing radiation and made from SMS materials, it is important to control the strength characteristics, primarily, the tensile strength in the transverse direction of the web stuff.
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Néspoli, Fabiana Gomes, Norberti Bernardineli, Roberto Brandão Garcia, Clovis Monteiro Bramante, Etiene Andrade Munhoz, and Augusto Bodanezi. "Low-concentrated nonvital bleaching effect on bond strength of composite resin restorations." Brazilian Dental Science 19, no. 3 (September 29, 2016): 82. http://dx.doi.org/10.14295/bds.2016.v19i3.1273.
Повний текст джерелаАнотація:
<p><strong>Objective:</strong> To investigate if short-term dentin bleaching with low-concentrated substances affects the bond strength of immediate resin composite restorations. <strong>Material and Methods:</strong> The buccal surfaces of fifty molar crowns were ground for dentin exposure and randomly assigned into 5 groups (n=10), according to the following treatments: sodium perborate + water; sodium perborate + 6% hydrogen peroxide; 6% hydrogen peroxide; 35% hydrogen peroxide (positive control), or no bleaching agent (negative control). The specimens were immediately restored with resin composite. Seven days after treatments, the shear bond test was performed in a universal test machine at a crosshead speed of 0.5 mm/min. Data were analyzed using ANOVA and Tukey’s HSD test (α = 0.05). <strong>Results:</strong> The shear bond strength mean values for the negative control group were higher than all experimental and positive control groups (p < 0.000), whose differences were not statistically significant (p > 0.05). <strong>Conclusion:</strong> Short-term dentin bleaching with sodium perborate+water, 6% hydrogen peroxide, or sodium perborate mixed with 6% hydrogen peroxide reduced the shear bond strength of immediate resin composite restorations.</p><p> </p><p><strong>Keywords</strong></p><p>Resins, synthetic; Hydrogen peroxide; Shear strength; Esthetics; Tooth.</p><div><hr align="left" size="1" width="33%" /><div><p> </p></div></div>
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Blum, Wolfgang. "Role of Boundaries in Control of Deformation Rate and Strength of Crystalline Materials." Materials Science Forum 604-605 (October 2008): 391–401. http://dx.doi.org/10.4028/www.scientific.net/msf.604-605.391.
Повний текст джерелаАнотація:
Plastic deformation of crystalline materials is not controlled by interaction among free dislocations only, but the interaction of free dislocations with internal boundaries. i) Low-angle boundaries: Modeling of deformation of pure materials with conventional grain size on the basis of structure evolution indicates that low-angle boundaries act as obstacles of free dislocations. The migration of the low-angle boundaries constitutes an essential recovery process determining the deformation resistance in the steady state. ii) High-angle boundaries: Severe plastic deformation transforms low-angle boundaries into high-angle ones. They differ in obstacle and recovery characteristics from low-angle boundaries, which explains the special properties of ultrafine-grained and nanocrystalline materials with regard to strength, strain rate sensitivity and ductility. iii) Phase boundaries in Ni-base superalloys enhance the strengthening by hard phases with strengthening by dense dislocation networks serving to reduce coherency stresses. It is concluded that internal boundaries play a crucial role in controlling the evolution of structure and strength in crystalline materials.
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Ueda, Masato, and Masahiko Ikeda. "Controlling of mechanical property in additive manufactured porous titanium by structural control and alloying for bone substitutes." MATEC Web of Conferences 321 (2020): 05004. http://dx.doi.org/10.1051/matecconf/202032105004.
Повний текст джерелаАнотація:
Mechanical properties of metallic materials can be controlled by not only alloy design but also constructing appropriate structure. A porous material with adequate pore structure showing appropriate mechanical properties has long been sought as the ideal bone substitute, because it exhibits low Young’s modulus and bone ingrowth. Additive manufacturing (AM) can produce metallic tailor-made products such as artificial bone, several joints etc. The purpose of this work was to control the mechanical property of porous Ti by controlling the porous structure. In addition, the characteristics of Ti-Zr-Fe alloys were also investigated as the materials for the AM. First, porous polylactic acid with rhombicuboctahedron-derived structure was prepared by a 3D printer to determine appropriated structure for bone substitutes. The compressive strength and Young’s modulus was strongly influenced by the minimum cross-sectional area fraction perpendicular to the loading direction. Then the porous Ti with similar structures were prepared by a laser AM. The strength and Young’s modulus were extremely low compared with the expected ones. Then Ti-xmass%Zr-1mass%Fe alloys (x=0, 5, 10) were prepared as the materials for the AM. Vickers hardness increased almost linearly with Zr content by solution hardening. Ideal bone substitutes would be produced by such structural design and alloying.
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Musa, M. H. A., Md Abdul Maleque, Mohammad Yeakub Ali, and Muhammad Hasibul Hasan. "Fracture Behavior Issues in HSLA Pipeline Steels - A Review." Advanced Materials Research 1115 (July 2015): 207–12. http://dx.doi.org/10.4028/www.scientific.net/amr.1115.207.
Повний текст джерелаАнотація:
The increasing demand for natural gas and oil as an important energy sources has led to rising the application of high strength low alloy steels (HSLA), which indicates continued growth of pipeline installations and the qualification of the actual pipeline network. A difficult problem to be solved for the economic and safe operation of high pressure pipelines is the control of ductile fracture propagation. As a result, the accurate estimation of the resistance to fracture and ductile fracture arrest in pressurized pipelines are important issues. Technology to ensure such control is critical for the structural integrity and safety of pipelines because the possibility of a running fracture opens-up lead to the catastrophic long-running failure of a pipeline which involve public safety and property damage and environment impact. The integrity and high reliability of pipelines depend on various factors including mechanical damage or external interference, fatigue cracks, material defects, weld cracks, improper welding, internal or external corrosion and, most of all, on the ageing of the physical state of the pipeline material and the welded joints during their prolonged use. In order to understand the current problems in the pipeline materials and to develop steels with higher strength, better toughness and weldability, this paper gives brief overview of the comprehensive of fracture behavior including crack initiation and propagation of high strength low alloy pipeline steels.
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Karaś, Zuzanna, and Aleksandra Truszczyńska-Baszak. "Non randomised trial of GRAVITY system therapy effectiveness in chronic, low intensity low back disc disease." Biomedical Human Kinetics 14, no. 1 (January 1, 2022): 151–58. http://dx.doi.org/10.2478/bhk-2022-0019.
Повний текст джерелаАнотація:
Abstract Study aim: Chronic low back pain (CLBP) is a therapeutically challenging pain syndrome. Physical exercises are the most common therapy used in CLBP treatment. The aim of the study was to verify if GRAVITY system exercise can be effective in the therapy of chronic discogenic low back pain. The GRAVITY system exercise aims at strengthening full body muscles using the trainee’s own body weight only. Material and methods: The study was registered at ClinicalTrials.gov Identifier: NCT04765293. We used TREND statement. The study populations were 50 patients with CLBP. The study population (group I) consisted of 25 patients who had GRAVITY system exercise. The clinical control group were 25 patients who received standard treatment in an outpatient clinic of National Health Fund. Before the start of the training, the patients’ had their muscle strength responsible for stabilizing the lumbar segment measured. We also measured patients’ Oswestry Disability Index (ODI) prior to and after the therapy cycle. The therapy was conducted twice a week for 40 minutes over the period of 4 weeks. The clinical control group were 25 patients who received treatment from the National Health Fund and had only standardised physical therapy (laser, ultrasound, cryotherapy and magnetic therapy) sessions for two weeks. Results. We found statistically significant reduction in pain and disability in the study population after the treatment, but muscle strength did not increase significantly. Conclusions: 1. GRAVITY system exercise might efficient in pain and disability reduction. Muscle strength did not increase after therapy. 2. Pain and disability had positive correlation with female sex, decreased physical activity and sedentary work.
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Yang, Xiangyu, Wenping Geng, Kaixi Bi, Linyu Mei, Yaqing Li, Jian He, Jiliang Mu, Xiaojuan Hou, and Xiujian Chou. "The Wafer-Level Integration of Single-Crystal LiNbO3 on Silicon via Polyimide Material." Micromachines 12, no. 1 (January 9, 2021): 70. http://dx.doi.org/10.3390/mi12010070.
Повний текст джерелаАнотація:
In situ measurements of sensing signals in space platforms requires that the micro-electro-mechanical system (MEMS) sensors be located directly at the point to be measured and in contact with the subject to be measured. Traditional radiation-tolerant silicon-based MEMS sensors cannot acquire spatial signals directly. Compared to silicon-based structures, LiNbO3 single crystalline has wide application prospects in the aerospace field owing to its excellent corrosion resistance, low-temperature resistance and radiation resistance. In our work, 4-inch LiNbO3 and LiNbO3/Cr/Au wafers are fabricated to silicon substrate by means of a polyimide bonding method, respectively. The low-temperature bonding process (≤100 °C) is also useful for heterostructure to avoid wafer fragmentation results from a coefficient of thermal expansion (CTE) mismatch. The hydrophilic polyimide surfaces result from the increasing of -OH groups were acquired based on contact angle and X-ray photoelectron spectroscopy characterizations. A tight and defect-free bonding interface was confirmed by scanning electron microscopy. More importantly, benefiting from low-temperature tolerance and radiation-hardened properties of polyimide material, the bonding strength of the heterostructure based on oxygen plasma activation achieved 6.582 MPa and 3.339 MPa corresponding to room temperature and ultra-low temperature (≈ −263.15 °C), which meets the bonding strength requirements of aerospace applications.
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Yang, Xiangyu, Wenping Geng, Kaixi Bi, Linyu Mei, Yaqing Li, Jian He, Jiliang Mu, Xiaojuan Hou, and Xiujian Chou. "The Wafer-Level Integration of Single-Crystal LiNbO3 on Silicon via Polyimide Material." Micromachines 12, no. 1 (January 9, 2021): 70. http://dx.doi.org/10.3390/mi12010070.
Повний текст джерелаАнотація:
In situ measurements of sensing signals in space platforms requires that the micro-electro-mechanical system (MEMS) sensors be located directly at the point to be measured and in contact with the subject to be measured. Traditional radiation-tolerant silicon-based MEMS sensors cannot acquire spatial signals directly. Compared to silicon-based structures, LiNbO3 single crystalline has wide application prospects in the aerospace field owing to its excellent corrosion resistance, low-temperature resistance and radiation resistance. In our work, 4-inch LiNbO3 and LiNbO3/Cr/Au wafers are fabricated to silicon substrate by means of a polyimide bonding method, respectively. The low-temperature bonding process (≤100 ℃) is also useful for heterostructure to avoid wafer fragmentation results from a coefficient of thermal expansion (CTE) mismatch. The hydrophilic polyimide surfaces result from the increasing of -OH groups were acquired based on contact angle and X-ray photoelectron spectroscopy characterizations. A tight and defect-free bonding interface was confirmed by scanning electron microscopy. More importantly, benefiting from low-temperature tolerance and radiation-hardened properties of polyimide material, the bonding strength of the heterostructure based on oxygen plasma activation achieved 6.582 MPa and 3.339 MPa corresponding to room temperature and ultra-low temperature (≈ -263.15 °C), which meets the bonding strength requirements of aerospace applications.
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Mezher, Thaer Matlab, Ashraf A. M. R. Hiswa, and Mustafa Salman Shubber. "Improvement of Mechanical Properties of Concrete by Using Polyproplene Fibers and Admixure." Defect and Diffusion Forum 398 (January 2020): 167–72. http://dx.doi.org/10.4028/www.scientific.net/ddf.398.167.
Повний текст джерелаАнотація:
Concrete is considered a low tensile resistance material and a weak material against cracking. The weak properties of concrete has been enhanced by utilizing fibers to reinforce it. In this research, the effects of the polypropylene fibers on several properties of plain concrete have been studied. It was found that the polypropylene fibers has enhanced the concrete ductility and the concrete crack control. The compressive strength of plain concrete has been increased by adding polypropylene fibers to it and also the flexural and splitting strengths. The best results were at fibers ratio of 1%. When the polypropylene fibers ratio has changed different effects on concrete properties have been obtained.
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Luo, Yun Rong, Tao Zeng, and Lei Fu. "Investigation on the Influence of Fatigue Damage on the Mechanics Property of Anti-Seismic Steel HRB400E Reinforcing Steel Bars." Applied Mechanics and Materials 368-370 (August 2013): 1678–82. http://dx.doi.org/10.4028/www.scientific.net/amm.368-370.1678.
Повний текст джерелаАнотація:
Low cycle fatigue (LCF) experiments on anti-seismic steel HRB400E reinforcing steel bars under constant total strain (0.6%) control were conducted on a MTS 809 servo-hydraulic material testing machine. The specimens were then subjected to quasi-static tension until they ruptures on the machine. The mechanical properties such as cyclic stress-strain behaviour, quasi-static strength, and quasi-static ductility of the material at various levels of fatigue damage were investigated .The test results indicate that when compared to its virgin state, in a certain cycles (about 80% fatigue life) the cycle-dependent behaviors of the material can cause a slight change in the strength and ductility, and the ductility of the steel has an opposite trend to the strength. However, a significant decrease occurs to both the strength and the ductility as the cyclic cycles exceeds about 80% fatigue life.
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M.R, Srinivasa, Y. S Rammohan, and Zahid Irfan. "Fretting Analysis of Aluminium 6061 Reinforced With Graphene." International Journal of Engineering & Technology 7, no. 3.12 (July 20, 2018): 568. http://dx.doi.org/10.14419/ijet.v7i3.12.16181.
Повний текст джерелаАнотація:
The application of Aluminium alloys becomes significant and most wide in the field of aviation industry. Aluminium 6061, because of its pro mechanical characteristics. Graphene is one of the allotropic forms of Carbon which is abundantly available in nature. The high tensile strength and low density of graphene is the added advantage as it is used as a reinforced material with Aluminium 6061. Graphene was found to be a more suitable reinforcing material that improves tribological properties of metal. Composite materials are mixtures of various parent materials resulting in the formation of materials having a mix of varied desired properties like low weight, larger stiffness, higher specific strength etc. The composite materials so obtained invariably have superior properties to their parental ones. So these materials become a really enticing notice for higher strengthened material for industrial sector. This paper primarily focuses on distinctive effects of utilizing Graphene as reinforcement for Al-6061in the view of tribological characteristics. Graphene has outstanding mechanical and physical properties, creating it a perfect reinforcement material for lightweight weight and high strength metal matrix composites (MMC) like Al-6061. Fabrication, being a important step, because it controls the microstructure, that successively determines the properties of the material, was conducted by stir casting. Stir casting additionally helped within the dispersion of Graphene uniformly within the metal matrix composite. To analyze the effect of tribological parameters damage resistance of the metal matrix composite, linear reciprocating tribometer was used.
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Salazar P, Araceli, R. H. Chávez T, J. A. Pichardo S, and Ulises Pichardo S. "PHYSICOCHEMICAL CHARACTERIZATION OF RAW MATERIALS FOR THE MANUFACTURING OF BRICK." EPH - International Journal of Science And Engineering 4, no. 1 (March 27, 2018): 1–5. http://dx.doi.org/10.53555/eijse.v4i1.130.
Повний текст джерелаАнотація:
Brick manufacturing is a traditional activity carried out by the practical knowledge transmitted person to person, why there is no documentation on the raw material and manufacturing process control. The objective of this study was to determine the physicochemical characteristics of the raw material used in the fabrication of the Bricks, as a first instance to be able to make future changes for the quality assurance of the process that allow increasing the resistance to compression of the bricks. A mechanical test about the compressive strength of bricks before and after heat treatment was made. In the analysis of elemental composition, the presence of the following elements was found: C, O, Na, Mg, Al, Si, K, Ca, Ti, Fe. These elements allowed to obtain a compressive strength of the bricks of 10 to 13kg/cm2 without heat treatment and 20 to 40 kg/cm2 with heat treatment. Morphologically particles of 5 to 300 micrometres were observed in the raw material, and in the Bricks of 15 to 250 micrometres. It is concluded that the great variation of particle size of the raw material leads to a low compressive strength. Other studies with more control in the homogenization of particle size are suggested to obtain greater compression strength. Besides the temperature control in the kiln used to heat treatment is needed. The International Standard ITINTEC 331,017, and the Standard NMX-C-404-1997, establishes 60N / cm2, and 24kg / cm2 as minimum respectively. This study serves as a basis for further studies to help control and ensure the quality of the bricks.
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Jongprateep, Oratai, Tunchanoke Khongnakhon, and Jednupong Palomas. "Composition-Microstructure-Property Relationships in BaTiO3 with Mg Addition." Key Engineering Materials 659 (August 2015): 58–63. http://dx.doi.org/10.4028/www.scientific.net/kem.659.58.
Повний текст джерелаАнотація:
Rising worldwide demands for energy encourages development of high-efficiency energy storage and capacitor components. Main requirements for dielectric materials employed in fabrication of high energy density capacitors include high dielectric constant, high dielectric breakdown strength, and low dielectric loss. Owing to its high dielectric constant and low dielectric loss [1], barium titanate is among common capacitor materials. Tailoring of dielectric properties of barium titanate can be achieved through controlled chemical composition, microstructure, and crystal structure. Synthesis and processing techniques, as well as doping of barium titanate, can be key factors to control the composition and structure, which consequently contribute to enhancement of dielectric constant in the material.
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Liu, Hanbing, Guobao Luo, Longhui Wang, Wensheng Wang, Wenjun Li, and Yafeng Gong. "Laboratory Evaluation of Eco-Friendly Pervious Concrete Pavement Material Containing Silica Fume." Applied Sciences 9, no. 1 (December 26, 2018): 73. http://dx.doi.org/10.3390/app9010073.
Повний текст джерелаАнотація:
Pervious concretes, such as sustainable pavement materials, have great advantages in solving urban flooding, promoting urban ecological balance, and alleviating urban heat island effect, due to its special porous structure. However, pervious concrete typically has high porosity and low strength. The insufficient strength and poor freeze-thaw durability are important factors that restrict its wide application, especially in seasonal frozen areas. Improving the strength and freeze-thaw resistance of pervious concrete will expand its application. Silica fumes, as an industrial by-product waste and supplementary cementitious material, play an important role in improving concrete performance. The objective of this paper was to study the effects of silica fumes on properties of sustainable pervious concrete. Silica fumes were used to replace cement with the equivalent volume method at different levels (3%, 6%, 9%, and 12%). The control pervious concrete and silica fume-modified pervious concrete mixtures were prepared in the lab. The porosity, permeability, compressive strength, flexural strength, and freeze-thaw resistance properties of all mixtures were tested. The results indicated that the addition of silica fumes significantly improved the strength and freeze-thaw resistance of pervious concrete. The porosity and permeability of all pervious concrete mixtures changed little with the content of silica fumes due to the adoption of the equal volume replacement method.
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Sakib, Nazmus, Rashidul Hasan, Azrul A. Mutalib, Maslina Jamil, Sudharshan N. Raman, and A. B. M. A. Kaish. "Utilization of Sugar Mill Waste Ash as Pozzolanic Material in Structural Mortar." Minerals 13, no. 3 (February 24, 2023): 324. http://dx.doi.org/10.3390/min13030324.
Повний текст джерелаАнотація:
Bagasse is produced as a waste in the sugar production process, which is used as fuel to stoke boilers in the sugar mills. The concluding product of this burning is residual sugarcane bagasse ash (BA), which is normally dumped or used as low-quality fertilizer. The ash for this study was collected from a reputed sugar mill located in the northern region of Bangladesh. Type I Portland cement (PC) was partially replaced with that finely ground bagasse ash without any pretreatment. The ground BA was used as a replacement for Portland cement at 5, 10, 15, 20, 25 and 30% of BA, respectively, in structural mortar. In addition, chemical characterization, specific gravity, X-ray diffraction (XRD), scanning electron microscopy (SEM), setting time, a strength activity index, compressive strength, water absorption, density and durability in a chloride environment of mortar were determined. The strength activity index result indicates that the used BA has the pozzolanic properties to be used as a partial cement replacement. The results showed that, at the age of 56 days, the mortar samples containing 5–15% ground bagasse ash had higher compressive strengths than the control mixture (mortar without ground bagasse ash). Mortar containing 15% ground bagasse ash had the highest mechanical and durability properties. Therefore, the substitution of 15% BA is acceptable for producing good quality structural mortar in the civil engineering construction field except in chloride environments.