Small Specific Gravity Research Articles

Pemanfaatan Limbah Kulit Tiram Sebagai Substitusi Semen pada Campuran Bata Ringan

Indonesian coastal areas of tourist spots that cause large amounts of seafood waste, such as oyster shells, led to the idea of reducing beach pollution by using oyster shells as a partial substitute for lightweight bricks as construction material. Lightweight bricks require high costs and have a heavy mass as walls, so oyster shell powder, which contains calcium carbonate and has a smaller specific gravity, is expected to qualify the Indonesian National Standard (SNI) requirements for lightweight bricks. The research method is quantitative experimental, which observes the effect of variables based on SNI. The composite of the lightweight brick combination is 0.35 Water Cement Ratio (FAS): 1 cement: 2 sand: 1 foam agent: 50 water, and the variable of oyster shell powder added to the cement is 0%, 3%, 6%, 9%, and 12% of cement. The quality test for oyster shell powder for making lightweight bricks based on SNI 8640, 2018, includes density, water absorption (porosity), and compressive strength tests. The result of average density analysis for 0% = 986 kg/m³, 3% = 954 kg/m³, 6% = 978 kg/m³, 9% = 920 kg/m³, and 12% = 903 kg /m³. According to the Indonesian National Standard (SNI), the porosity test results maximum is 25%, the result of average porosity analysis at 0% = 21.2%, 3% = 19.2%, 6% = 17.2%, 9% = 23%, and 12% = 24.6%. Compressive strength analysis results at 0% = 2.3 MPa, 3% = 1.9 MPa, 6% = 2.1 MPa, 9% = 1.7 MPa, and 12% = 1.6 MPa. In conclusion, oyster shell powder waste can reduce density, reduce porosity to the optimum point, increase the porosity afterward, increase compressive strength to the optimum point, and reduce compressive strength after passing the optimum point.

Failure mode analysis and prediction model of additively manufactured continuous carbon fiber‐reinforced polylactic acid

AbstractCarbon fiber‐reinforced composites are widely used in aerospace, rail transportation, and new energy vehicles due to their small specific gravity as well as good mechanical and chemical properties. Additive manufacturing of continuous carbon fiber‐reinforced polymer composites is an innovative composite manufacturing technique. In this paper, bending and shear specimens with different hatch spacing and layer thicknesses were prepared by fused filament fabrication (FFF) technique and subjected to three‐point bending experiments and interlayer shear experiments, respectively. The results showed that the maximum flexural strength and flexural modulus of the fabricated parts were 383.81 MPa and 41.23 GPa, respectively, and the maximum interlayer shear strength was 13.64 MPa. Finally, an optimized criterion for determining fiber kinking, fiber breakage, and matrix damage was proposed by considering in situ strength variations induced by process parameters. This new model was subsequently validated and could provide a method for fracture predicting of additive manufactured carbon fiber‐reinforced composites.Highlights CCFRC parts with different porosities were prepared by adjusting the layer thickness and hatch spacing. The bending and interlaminar shear damage mechanisms of CCFRC fabrications are revealed, and the effects of layer thickness and hatch spacing on their mechanical properties are investigated. Introduction of additive manufacturing factors to optimize failure models for CCFRC parts. Introduction of additive manufacturing coefficients to accurately predict the interlaminar shear strength of CCFRC parts by AM.

Defect Detection Method of Carbon Fiber Sucker Rod Based on Multi-Sensor Information Fusion and DBN Model.

Because of its unique characteristics of small specific gravity, high strength, and corrosion resistance, the carbon fiber sucker rod has been widely used in petroleum production. However, there is still a lack of corresponding online testing methods to detect its integrity during the process of manufacturing. Ultrasonic nondestructive testing has become one of the most accepted methods for inspection of homogeneous and fixed-thickness composites, or layered and fixed-interface-shape composites, but a carbon fiber sucker rod with multi-layered structures and irregular interlayer interfaces increases the difficulty of testing. In this paper, a novel defect detection method based on multi-sensor information fusion and a deep belief network (DBN) model was proposed to identify online its defects. A water-immersed ultrasonic array with 32 ultrasonic probes was designed to realize the online and full-coverage scanning of carbon fiber rods in radial and axial positions. Then, a multi-sensor information fusion method was proposed to integrate amplitudes and times-of-flight of the received ultrasonic pulse-echo signals with the spatial angle information of each probe into defect images with obvious defects including small cracks, transverse cracks, holes, and chapped cracks. Three geometric features and two texture features from the defect images characterizing the four types of defects were extracted. Finally, a DBN-based defect identification model was constructed and trained to identify the four types of defects of the carbon fiber rods. The testing results showed that the defect identification accuracy of the proposed method was 95.11%.

Molybdenum Sulfide Selenide Nanosheets Synergized with Nitrogen‐Rich Carbon Frameworks toward High Performance and Stable Sodium Storage

AbstractTransition metal dichalcogenides attract much attention in fabricating advanced electrodes for sodium‐ion batteries. Herein, to improve electrochemical activity and structural stability and thus enhance sodium storage performances, molybdenum sulfide selenide (MoSSe) nanosheets synergized with nitrogen‐rich carbon nanoframeworks (NCNF@MoSSe) are constructed through a combination of hydrothermal technique and template method with (NH4)2MoS4 and Se powders as the reactants and N‐rich polypyrrole nanotubes as the template. On the one hand, nitrogen‐rich carbon nanoframeworks with high conductance and thermal stability can serve as an effective carrier for an ideal charge migration. On the other hand, compared to MoS2 or MoSe2, MoSSe is a more desirable active material with smaller specific gravity and proper interlayer distance. The structural analyses demonstrate the strong core–shell combination and the good structural stability of the NCNF@MoSSe hybrids. As results, the NCNF@MoSSe hybrids can work as anode material with enhanced sodium storage properties and deliver a high specific capacity (502 mAh g−1 at 0.1 A g−1) as well as a good cyclic stability (323.3 mAh g−1 at 2.0 A g−1 after 700 cycles).

Characterization and functional evaluation of surface texture of micro eccentric shaft based on multi-index

Micro eccentric shaft has important application in many high-tech fields because of its small specific gravity, material, and energy saving. The machined surface texture has an indispensable influence on the surface integrity and the final functional capability. However, due to the micro scale and weak rigidity, it is difficult to characterize the surface texture and evaluate the functionality by traditional quantitative parameters. In order to comprehensively realize the surface texture characterization and functional analysis, a mathematical model is established to simulate the surface texture machined with different cutting tools. Then the surface microscopic profile and functional performance of the surface texture are analyzed by amplitude distribution function (ADF) and bearing area curve (BAC), and the surface texture is also evaluated by fractal dimension, which can avoid the negative effects of scale and resolution. Furthermore, power spectrum density (PSD) is utilized to analyze the relationship between the process dynamic state and geometrical specification of the surface texture. The validity of experimental results shown that the microscopic height distribution of surface machined by flat end milling cutter tends to be more random and there are more microscopic geometric features than that of the ball end milling cutter. The machined surface obtained by the flat end milling cutter has better load bearing, wear resistance, and liquid retention capability.

Study on a New Environmentally Friendly Synthetic Fluid for Preparing Synthetic-Based Drilling Fluid

In view of the pollution problems related to using oil-based drilling fluids, we prepared a new environmentally friendly synthetic fluid, namely, NSF, for use in synthetic-based drilling fluid instead. We used heavy hydrocarbons from Daqing as raw material in our preparation and employed few-steps refining techniques, such as hydrodesulfurization, hydrodearomatization, and hydrogenation. After the treatment, the sulfur and aromatic hydrocarbon contents in the NSF were <0.5 mg/L, meeting international environmental standards. NSF is composed mainly of C12-C22 hydrocarbons, and is characterized by low impurity content, small specific gravity, and easy degradation. In addition, the LC50 value is >1,000,000 mg/L water-soluble fraction; therefore, its toxicity is <10% of that of diesel in oil-based drilling fluid and, as the flash point of NSF is about 134°C, the related fire hazard is low. The synthetic-based drilling fluid with NSF has the advantage of causing no swelling damage to the reservoir, and saves the cost of drilling fluid because it doesn't need to deal with the environmental problems (the sulfur and aromatic hydrocarbon contents were <0.5 mg/L) and field problems caused by the reaction between drilling fluid and reservoir, and greatly increases the ROP through reducing the drill pipe sticking and with C12-C22 hydrocarbons in synthetic-based fluid, and safely uses, and has stable drilling fluid performances which are flash point (134°C) and low fire hazard. We have therefore achieved our aim of preparing a high-quality and non-toxic synthetic fluid, of which the aromatic hydrocarbon and sulfur contents meet international standards. Using this synthetic-based drilling fluid therefore facilitates environment protection drilling.

Behavior of bagasse ash-calcium carbide residue stabilized soil with polyester fiber inclusion

Bagasse ash is a non-cohesive waste material having small specific gravity that is relatively smaller than that of normal soil, and it behaves as pozzolanic material. Whereas calcium carbide residue (CCR) is hazardous waste materials containing high calcium. Research about using of bagasse ash and CCR is continually in progress. In this paper, a series of experimental studies was undertaken to study the individual and combined effects of randomly oriented polyester fiber inclusions on bagasse ash-CCR stabilized soil. The first step was carried out compaction test on 7, 14, 21, 28 and 36 days-cured soil-mixed with 8% CCR to get optimum curing period that was found at 28 days. Then, the test of soil + 8% CCR + bagasse ash with proportion of 3, 6, 9 and 12% was performed on unconfined compression test to get the best proportion of bagasse ash. That was found 9%. Finally, compaction, direct shear, and unconfined compression tests were performed on 2% fiber inclusion on bagasse ash-CCR stabilized soil (soil + 8% CCR + 9% bagasse ash). Stiffness and maximum dry density (MDD) of soil increase due to additional of CCR, however, it is not significantly affected by the polyester fiber inclusion. Improvement shear strength of stabilized soil is mostly affected by the increase of cohesion rather than due to improvement of internal friction angle. Ductility of bagasse ash-CCR soil mixture increased because of the present of polyester fiber reinforcement.

Cellulose/vaterite nanocomposites: Sonochemical synthesis, characterization, and their application in protein adsorption

Vaterite is recognized as an important biomedical material owing to its features such as high specific surface area, high solubility, high dispersion, and small specific gravity. Herein, we report a facile and green sonochemical route to prepare vaterite nanospheres (assembled from rice-shaped nanoparticles) with average diameter of 206–246 nm by using cellulose as substrate. The important role of cellulose concentration on the phase of the products was systematically investigated, and the formation mechanism of vaterite was proposed. Moreover, the as-prepared cellulose/vaterite nanocomposites have a good cytocompatibility and a relatively high protein adsorption ability using hemoglobin as a model protein. These results indicate that the as-prepared cellulose/vaterite nanocomposites are promising for applications in biomedical fields, such as protein adsorption.

Manufacture of Reclaimed Fiber Non-Woven for Sound Absorption

Recycling is the process of making or bringing out new products from a product that has originally served its purpose. The use of non-woven for noise reduction is based on two major advantages of these materials, namely low production costs and small specific gravity. Through this thesis, an attempt was made and implemented an innovative technique of developing stitch bonded non-woven by using recycled fiber. Knitted wastes were collected from cut and sew knitwear factories and recycled by using fabric opening machine in Adey abeba textile factory. The opened fibers are carded by mechanical carding machine by varying the number of layers. Six nonwoven samples are manufactured by stitching the web structure with core spun yarn. The manufactured reclaimed fiber stitch bonded nonwoven sound absorption coefficients were measured according to ASTM E 1050 standard by an impedance tube. The results revealed that the sound absorption coefficient increased with increasing frequency level of 500 Hz, 1000 Hz, 1500 Hz, 2000 Hz, 2500 Hz and 3000 Hz. Factors influencing sound absorption of nonwoven materials such as fabric thickness, areal density, air permeability and thermal conductivity were tested. The results revealed that while thickness increases the sound absorbing performance also increases. Low frequency sound absorption has direct relationship with thickness. However, at higher frequencies thickness has insignificant effect on sound absorption. Less dense and more open structure absorbs sound of low frequencies. Denser structure performs better for frequencies above 2000 Hz. Air permeability of the stitch bonded nonwoven decreases the sound absorption performance increases. The mechanism of sound absorption was conversion of sound energy in to heat but the effect of thermal conductivity of stitch bonded nonwoven structure was very small.

Study on the Multiwalled Carbon Nano tube Mixed EDM of Al-SiCp Metal Matrix Composite

Present study investigates the feasibility of machining Al-SiCp metal matrix composite by multiwalled carbon nanotube (MWCNT) mixed electric discharge machining (EDM). Experiments were conducted on indigenously developed nano powder mixed electric discharge machining (NPMEDM) setup. Material removal rate (MRR) and surface roughness (SR) were considered as the p erformance measures. From the outcome of the results, it has been concluded that straight pin shape and small specific gravity of CNTs leads to uniform dispersion in the EDM dielectric fluid, which in turn, leads to enhancement in MRR and reduction in SR.

Simulation of composite material exposed to lighting of component A

Composite material has many advantages such as small specific gravity, high strength and good corrosion resistance. So it is widely used to the aircraft manufacturing industry. Composite material has a poor conductivity, lighting current is difficult to quickly to go out when subjected to lighting, resistance heat would cause serious heat damage and endanger the safety of aircraft flying. In this paper, the finite element analysis software is used simulate the thermal–electrical effect of carbon fibre epoxy composite plates when struck by lightning. Simulation results show that maximum potential of the composite is consistent with the trends of the exposed lighting current waveforms, lighting current goes along with the direction of the largest conductivity of the surface the composite plates, resistance heat generated by lighting current also mainly goes along the surface so that the thermal damage of the composite plate are concentrated on the surface. The thermal injury of the next layer in influenced by the angle of the upper layer. The thermal injury of the layer with 90° fibre angle is more serious, so the amount of the layer with 90° fibre angle should be as little as possible. The paper obtains the thermal damage distribution of the composite plate when struck by lighting and provides a reference for assessing the reliability of the composite exposed to lighting.

Physical modeling of lateral spreading induced by inclined sandy foundation in the state of zero effective stress

The state of zero effective stress is a situation at which the effective stress of saturated sand decreases to zero in the process of liquefaction. In the state of zero effective stress, sand particles suspend in water and the foundation is vulnerable to much large lateral deformation. The state of zero effective stress can be achieved through dynamic loading tests, but the obtained state is difficult to sustain a steady situation. To simulate the suspended sand in water under fully liquefied condition, plastic sand, characterized by small specific gravity, is used instead of quartz sand to build an inclined foundation. Salt water with similar density is used to pass in slowly near bottom of the foundation. As observed in tests, the plastic sand is able to suspend in sodium chloride solution (salt water) of a specific density and thus this model can be used to simulate the lateral spreading of a foundation under zero effective stress state. Lateral deformation occurs within a certain depth beneath the ground and the magnitude increases from the bottom up, showing nonlinear behaviors. This paper presents a physical modeling approach for achieving the state of zero effective stress under static laboratory condition.

Viability and vigour of ageing pea seeds with various densities

Pea seed lots (of big and small densities and a control) were stored for six months in hydrostats in relative air humidity 90 and 50 per cent, at 21°C. Viability was determined on the basis of germination rate (energy) and capacity; vigour on the basis of sprout growth analysis, conductometric measurements and over-all dehydrogenase activity in the embryonic axes (tigella). Seeds stored in a high relative air humidity were losimg their viability and vigour more quickly than did those stored in a dry air. Seeds of big density were preserving better and ageing slower than seeds of small specific gravity.

Why to synthesize vaterite polymorph of calcium carbonate on the cellulose matrix via sonochemistry process?

Vaterite is an important biomedical material due to its features such as high specific surface area, high solubility, high dispersion, and small specific gravity. The purposes of this article were to explore the growth mechanism of vaterite on the cellulose matrix via sonochmistry process. In the work reported herein, the influences of experimental parameters on the polymorph of calcium carbonate were investigated in detail. The calcium carbonate crystals on the cellulose matrix were characterized by means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Experimental results revealed that all the reactants, solvent, and synthesis method played an important role in the polymorph of calcium carbonate. The pure phase of vaterite polymorph was obtained using Na2CO3 as reactant in ethylene glycol on the cellulose matrix via sonochmistry process. Based on the experimental results, one can conclude that the synthesis of vaterite polymorph is a system process.

Experimental Research of Tin Ore from Kazakhstan

The paper recovered the tin from a refractory tin ore in Kazakhstan. The grade of tin in raw ore is 1.19%. Through technological mineralogy study, we found the tin was mainly in the forms of cassiterite and stannite. Considering the gravity process would make the stannite lost in tailings because of its small specific gravity, we explored the flotation to recover the tin. In fact, the grade and recovery of tin were bad by collectors contrast test. Finally, we adopted gravity flowsheet to recover cassiterite. The recovery of tin is not high because the tin in the form of stannite lost in tailings. As a result, the tin concentrate with a grade of 21.56% and the recovery of 52.90% were obtained.

A study on the manufacturing of digital camera barrel using magnesium alloy

In recent year, there has been a growth of the manufacture and application of magnesium products. For Magnesium alloys take advantage small specific gravity and relatively high strength, shielding electromagnetic waves. However, there are so many studies to assure good formability because Magnesium alloy is difficult to form. The AZ31B alloy shows an excellent workability at temperatures from 250 °C to 400 °C. Temperatures higher than 400 °C are not suitable for forming of the AZ31B alloy because of heavy oxidation. Forming temperature and heat transfer of Magnesium alloy to the molds, punch velocity, friction coefficient and geometric shape of molds are important factors to forge the components successfully. The forming factors of press forging on AZ31B have been studied by finite element analysis that was done with DEFORM/3D software. By conducting a circular design which included predictive experiments, evaluation of the outcome of actual products, and process modifications, the optimum conditions were established for a forging process to manufacture a magnesium alloy camera barrel.

Crystallisation of Silicon on Reinforcement Fibres as a Consequence of Overheating of Matrix Metal during Saturation in MMC

Metal-matrix composites for many years have been widely used as engineering material all over the world, also in Poland. It is due to good construction properties, small specific gravity, ease of product formation, also large size items, diversity of manufacturing methods, and great possibilities of changing their properties depending on the output products used [. The authors of this study deal with metal-matrix composites made by casting. One of the methods they use in their research includes the saturation of the reinforcement structure (short disordered fibres pressed like felt, forming a profile, called preform) with metal liquid matrix under pressure. Phenomena occurring in the production of a composite material are similar to those taking place during making casts from traditional materials (cast steel, cast iron, non-ferrous metal alloys). This article is an overview of a problem encountered while detecting and describing defects of metal-matrix composite materials produced by saturation. It focuses on phenomena that take place during casting solidificationespecially the influence of the matrix (with different temperatures of liquid metal) on the reinforcement during its saturation and crystallisation of silicon plates on it.

Advantages of carbon nanotubes in electrical discharge machining

Carbon nanotubes (CNTs) have a small specific gravity and a straight-pin shape, which allow them to continuously float and to uniformly disperse throughout the entire dielectric-filled cavity with little agglomeration during electrical discharge machining (EDM). In the past, powder mixtures of silicon, aluminum, and chrome have been used in the EDM process. However, there are concerns about flushing the controlled gap between the electrode and the workpiece because of their heavy specific gravity and their associated non-uniform dispersion in the dielectric. In this study, the effect of adding CNT powders to the dielectric on the surface integrity and the machining efficiency of the workpiece were investigated. CNTs can avoid the agglomeration problem. The CNTs were fabricated by chemical vapor deposition and added to the dielectric at a concentration of 0.4 g/l. The average surface roughness of 0.09 μm was achieved within 1.2 h, and the material defects of the recast layer and the micro-cracks were considerably reduced. The adopted processing parameters were a negative electrode polarity, a discharge current of 1 A, a pulse duration of 2 μs, an open-circuit voltage of 280 V, and gap voltage of 70 V. This technology improved the surface finish by 70% and the machining time by 66%. The achievement is attributed to the nanoscale characteristics of the CNTs in the dielectrics. The surface force became large and was able to balance the gravity body force of the CNTs. Consequently, the electric arcs were well dispersed and more uniform across the electrode gap, thus significantly enhancing the performance of the electrical discharge. It is expected that carbon nanotubes will be used in many EDM applications.

AZ31 마그네슘 합금판재의 소성변형특성

In recent years, there has been a growth of the manufacture and application of magnesium products because of its small specific gravity as well as its relatively high strength. However, there are so many studies to assure good formability because magnesium sheet alloy is difficult to form. In this study, uniaxial tensile and biaxial tensile tests of AZ31 magnesium sheet alloy with thickness of 1.2mm were performed at room temperature. Uniaxial tensile tests were performed until <TEX>$7{\%}$</TEX> of engineering strain. Lankford values and stress-strain curve were obtained. Biaxial tensile tests with cruciform specimen were performed until the breakdown of the specimen occurs. The yield loci were calculated by application of plastic work theory. The results are compared with the theoretical predictions based on the Hill and Logan-Hosford model. In this study, Hill's 1979 yield function for the case of m=2.8 and Logan-Hosford yield function for the case of M=8 give good agreements with experimental results. However, next study will be performed at warm-temperature because the specimens are broken under the <TEX>$0.5{\%}$</TEX> of equivalent strain at biaxial tensile test.

Prediction of Test Weight from a Small Volume Specific Gravity Measurement

ABSTRACTThe specific gravity (cm3/g) of small (20 and 40 g) samples of soft wheats from three states were rapidly measured and compared with bulk density (g/cm3) measurements (microtest weights). Specific gravities were correlated with test weights for both cleaned and uncleaned samples. The relationship between specific gravity and test weight was linear unless the samples were severely shriveled. Operator effect was not statistically significant. Simple linear regression analysis produced equations that predicted with high R2 value microtest weights from specific gravity measurements. Both 20 and 40 g sample sizes were satisfactory. However, 40 g samples produced better statistical relationships.