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1
Kantola, Jani, Kari Mäntyjärvi e Jussi A. Karjalainen. "Laser Assisted Cutting of Abrasion Resistant Steel". Key Engineering Materials 504-506 (fevereiro de 2012): 1371–76. http://dx.doi.org/10.4028/www.scientific.net/kem.504-506.1371.
Resumo:
Abrasion resistant (AR) steels offer excellent hardness and strength properties in applications as mining and earth moving machines. As an outcome of high hardness AR steels can be used to produce durable, light-weight and energy saving products. However, their mechanical processing can be challenging as the hardness of the material approaches the hardness of the tooling used. This places high forces on cutting tools and machines, which, in turn, increases wear and causes early breakdown. This research examines whether the laser treatment of AR steels can be used to aid guillotine shearing. The tested material was abrasion resistant steel with hardness of 400 HBW. Two different laser treatments were examined: local laser heat treatment and laser milling. The aim of laser heat treatment was to change the original martensitic microstructure locally into weaker structure, beneficially for shearing. Narrow grooves were made along the cut line by laser milling, and then the plate cut along them. The effect of local laser heat treatment and the fracture initiating effect of the groove was evaluated from the cutting force. Microhardness tests and micro photos were taken after laser heat treatments. The results indicated that the shearing force of AR steels can be reduced up to 25% with the aid of laser heat treatments. Laser milling had only a slight effect to the shearing force of up to about 8%. In addition, the relative depth of the laser milled groove is estimated at the same range, thus force reduction is mainly due to reduction of material thickness.
2
Guan, Chengyu, Jun Zou, Qingchang Chen, Mingming Shi e Bobo Yang. "Effect of Different Bonding Materials on Flip-Chip LED Filament Properties". Applied Sciences 10, n.º 1 (19 de dezembro de 2019): 47. http://dx.doi.org/10.3390/app10010047.
Resumo:
This article researches the effect of Sn-based solder alloys on flip-chip light-emitting diode LED (FC-LED) filament properties. SEM images, shearing force, steady-state voltage, blue light luminous flux, and junction temperature were examined to demonstrate the difference between two types of FC-LED filaments welded with two solders. The microstructure surface of Sn90Sb10 filament solder joints was smoother and had fewer voids and cracks compared with that of SAC0307 filament solder joints, which indicates that the Sn90Sb10 filaments had a higher shearing force than the SAC0307 filaments; moreover, the average shearing force was beyond 200 gf (standard shearing force). The steady-state voltage and junction temperature of the Sn90Sb10 solder-welded FC-LED filament were lower, and the Sn90Sb10 filament had a relatively higher blue light luminous flux. If high reliability of the solder joints and better photoelectric properties of the filaments are required, this Sn90Sb10 solder is the best bonding material for FC-LED filament welding.
3
Shirobokov, Anton, Fritz Klocke, Oksana Baer, Andreas Feuerhack, Daniel Trauth e Martin Wahl. "Finite element modelling of cutting force in shearing of multidirectional carbon fibre reinforced plastic laminates". Journal of Composite Materials 52, n.º 28 (19 de abril de 2018): 3865–74. http://dx.doi.org/10.1177/0021998318771145.
Resumo:
Lightweight structural components made of carbon fibre reinforced plastics are manufactured near-net-shape. However, in order to fulfil geometrical or functional requirements, carbon fibre reinforced plastic components have to be trimmed and pierced in a finish processing step. Shearing is a highly productive technology that is potentially suitable for cost-effective finishing of carbon fibre reinforced plastic components in high-volume series production. Shearing of carbon fibre reinforced plastic has not yet been sufficiently researched. Cutting force is an important characteristic of the shearing process. Up to now, there exists limited knowledge on numerical modelling of the cutting forces in carbon fibre reinforced plastic shearing. In order to address this, a finite element process model of carbon fibre reinforced plastic trimming was developed in this work. The process modelling included a formulation of continuum mechanical material model for a unidirectional ply as well as a development of a kinematic model of the trimming process. The developed finite element process model was validated by means of experimental data. The simulated and experimentally determined maximum specific cutting forces demonstrated a very good qualitative and quantitative agreement.
4
Rinck, Philipp M., Alpcan Gueray e Michael F. Zaeh. "Modeling of cutting forces in 1-D and 2-D ultrasonic vibration-assisted milling of Ti-6Al-4V". International Journal of Advanced Manufacturing Technology 119, n.º 3-4 (30 de novembro de 2021): 1807–19. http://dx.doi.org/10.1007/s00170-021-08355-x.
Resumo:
AbstractTo meet the modern demands for lightweight construction and energy efficiency, hard-to-machine materials such as ceramics, superalloys, and fiber-reinforced plastics are being used progressively. These materials can only be machined with great effort using conventional machining processes due to the high cutting forces, poor surface qualities, and the associated tool wear. Vibration-assisted machining has already proven to be an adequate solution in order to achieve extended tool lives, better surface qualities, and reduced cutting forces. This paper presents an analytical force model for longitudinal-torsional vibration-assisted milling (LT-VAM), which can predict cutting forces under intermittent and non-intermittent cutting conditions. Under intermittent cutting conditions, the relative contact ratio between the rake face and the sliding chip is utilized for modelling the shearing forces. Ploughing forces and shearing forces under non-intermittent cutting conditions are calculated by using an extended macroscopic friction reduction model, which can predict the reduced frictional forces under parallel and perpendicular vibration superimposition. The force model was implemented in MATLAB and can predict cutting forces without using any experimental vibration-assisted milling (VAM) data input.
5
Fujio, Y., N. Igura e I. Hayakawa. "Depolymerization of Molten-Moisturized-Starch Molecules by Shearing-Force under High Temperature". Starch - Stärke 47, n.º 4 (1995): 143–45. http://dx.doi.org/10.1002/star.19950470405.
6
Varenberg, M., e S. Gorb. "Shearing of fibrillar adhesive microstructure: friction and shear-related changes in pull-off force". Journal of The Royal Society Interface 4, n.º 15 (27 de fevereiro de 2007): 721–25. http://dx.doi.org/10.1098/rsif.2007.0222.
Resumo:
To characterize the effect of shearing on function of fibrillar adhesive microstructure, friction and shear-related changes in pull-off force of a biomimetic polyvinylsiloxane mushroom-shaped fibrillar adhesive microstructure were studied. In contrast to a control flat surface, which exhibited pronounced stick–slip motion accompanied with high friction, the fibrillar microstructure demonstrated a stable and smooth sliding with a friction coefficient approximately four times lower. The structured contact also manifested zero pull-off force in a sheared state, while the flat surface exhibited highly scattered and unreliable pull-off force when affected by contact shearing. It appears that the fibrillar microstructure can be used in applications where a total attachment force should be generated in a binary on/off state and, most surprisingly, is suitable to stabilize and minimize elastomer friction.
7
Kohta, Masushi, Shunji Yunoki e Junko Sugama. "Effect of prophylactic dressings to reduce pressure injuries: a polymer-based skin model". Journal of Wound Care 33, Sup2 (1 de fevereiro de 2024): S4—S9. http://dx.doi.org/10.12968/jowc.2024.33.sup2.s4.
Resumo:
Objective: This study evaluated the effect of pressure injury (PI) prophylactic dressings used for patients at high risk of PI development to reduce friction, shear force and pressure, and their combined force, in an original polymer-based skin model. Method: A low-friction outer-layer hydrocolloid (LFH) dressing and a multilayered silicone foam (MSF) dressing were used. Before application, compression and friction properties were measured. Our original experimental model—the ‘simulated skin-shearing test’—consisted of: a weight; a polyurethane-based skin model containing a three-axis tactile sensor; dressings; a table covered with bedsheets; and a mechanical tester, by which the interface friction force, internal shear force and pressure were measured continuously during skin model movements. An estimated combined force generated by internal shear and pressure was represented as a vector. A model with no dressing was used as a control. Results: The LFH dressing had significantly higher compression strength versus the MSF dressing. In contrast, the dynamic coefficient of friction was lower for the LFH dressing versus the MSF dressing (p<0.05). In simulated skin-shearing test results, shear forces were 0.45N and 0.42N for LFH and MSF dressings, respectively, with no significant difference. The estimated combined force was lower for the MSF dressing compared with that of the LFH dressing and control. Conclusion: The shear force-reducing effect in the skin model was equivalent between the LFH and MSF dressings. However, the MSF dressing significantly reduced the force generated by a combination of internal shear force and pressure compared with the LFH dressing.
8
Sun, Jun, Yu Ling Wang e Bo Lu. "Optimal Design and Process Analysis of the Blade for High-Speed Shearing Stainless Steel Tube". Advanced Materials Research 139-141 (outubro de 2010): 797–800. http://dx.doi.org/10.4028/www.scientific.net/amr.139-141.797.
Resumo:
This paper mainly researches on the effect from high-speed shearing tool to the quality of stainless steel tube cutting. At first, the relationship between contour line of vertical blade and the direction of shear force and chip flow are studied, and the influence on the quality of shearing caused by the size of blanking clearance is analyzed. Then a new blade contour line that made most of the iron chippings is located outside of the tube and reasonable blanking clearance is obtained. Further, based on the tearing caused by single-blade shear on the top of steel tube, the shape and angle of the vertical blade are studied, and the structure of the vertical blade nose is optimized, which improves the shearing quality of the blade. Finally, the numerical simulation of the process of shearing is done to verify the feasibility of the designed structure by the finite element software DEFORM.
9
Clark, Abe, Derek Olson, Andrew Swartz e Sobing Phua. "A granular physics-based model for sediment dispersion". Journal of the Acoustical Society of America 153, n.º 3_supplement (1 de março de 2023): A87. http://dx.doi.org/10.1121/10.0018263.
Resumo:
Current models of dispersion in marine sediments include losses due to fluid viscosity and shearing at grain-grain contacts. An additional loss mechanism, which is well established in granular physics but is not included in existing models, is the inelasticity of normal compression at grain-grain contacts. Additionally, force-bearing contact networks, often called “force chains,” involve primarily normal compressive forces. These “force chains” are known to play a dominant role in force transmission in granular materials, including wave propagation. Using theoretical analysis of a 1D model “force chain” as well as DEM simulations in higher spatial dimension, we show that this granular mechanics perspective, where forces are transmitted along lossy force chains, may be able to explain salient features of the acoustic properties of marine sediments. In particular, the low and high-frequency behavior of the attenuation coefficient match a large collection of experimental data. [This was supported by the Office of Naval Research.]
10
Csizmazia, Zoltán, Ilona Nagy Polyák e Attila Kőkuti. "Basic Research for the Development of Fertiliser Spreaders". Acta Agraria Debreceniensis, n.º 24 (11 de outubro de 2006): 52–57. http://dx.doi.org/10.34101/actaagrar/24/3225.
Resumo:
The knowledge of the physical characteristics of fertiliser particles is essential for the constructors and operators of fertiliser distributors. Among physical characteristics, the most important are the frictional and aerodynamic properties for the description of particle movement. Adjustable angled slopes, shearing boxes and various rotating disks are used to identify frictional properties. We have developed a high precision shearing box with digital force measuring cells and a distance signaller (incremental transducer) that we use for slide tests efficiently. We measured the frictional characteristics of 6 different fertilisers: the inner coefficient of friction and the coefficient of friction on ten test surfaces most commonly used in machinery, and we specified the relationship between displacement, loading and the coefficient of friction. We can conclude that the material of the frictional surface significantly influences the force of friction.However, our experience tells us that the shearing box is not suitable for the measurement of the inner friction, since the examined particles slide on the metal surface of the shearing box in a growing extent in the course of displacement, so it does not measure the real inner friction. Therefore, in our experiment we have developed rotating shearing equipment with a constant shearing surface to identify the inner friction. We tested the equipment with fertilisers and we identified the inner frictional characteristics of 6 different fertilisers. With the developed rotating shearing apparatus we could measure the real inner friction of the particles.To identify the aerodynamic characteristics of granules, wind tunnels and free-fall tests are used. An elutriator have been developed for our investigation. We have used fertilisers for testing the measuring equipment and we have identified the aerodynamic characteristics of 6 different fertilisers.
11
Izamshah, Raja, Nurul Husna, Mohd Hadzley, Mohd Amran, Mohd Shahir Kasim e Sivaraos. "Optimization of Cutter Geometry Features to Minimise Cutting Force on Machining Polyetheretherketone (PEEK) Engineering Plastic". Applied Mechanics and Materials 761 (maio de 2015): 282–86. http://dx.doi.org/10.4028/www.scientific.net/amm.761.282.
Resumo:
Machining of thermoplastic material poses several challenges due to its low melting temperature and high thermal expansion which directly related to cutting force. Thus, controlling the cutting force and temperature is desirable for machining polyetheretherketone (PEEK). The cutting force is dependent on friction and shearing action produced by the tool. It is indicated the cutting force is significantly affected by tool cutter geometry. This paper aims to control the cutting force by optimizing the cutter geometries especially rake, clearance and helix angle on machining PEEK. The two –flutes of solid carbide ball nose end mills were used to conduct the experiments and the cutting force acquired was measured using piezoelectric dynamometer. Response Surface Methodology (RSM) approach was applied to design and analyse the optimal combination of tool geometry feature for machining PEEK. Based on obtained results, the best optimal values of tool geometry which contribute to minimum of cutting force were 17° rake angle, 26° of helix angle and 10° of clearance angle. The best control of tool geometry ultimately improves the cutting performance and reduces defect caused by high cutting forces.
12
Rusakov, A. N., e M. S. Turgenbaev. "Monitoring of the cutting device of shearing machines for sheep". Sel'skohozjajstvennaja tehnika: obsluzhivanie i remont (Agricultural Machinery: Service and Repair), n.º 9 (5 de setembro de 2021): 18–22. http://dx.doi.org/10.33920/sel-10-2109-03.
Resumo:
The article presents monitoring of cutting machines of sheep shearing machines. In general, shearing machines have low-cutting machines, which is due to the production of the largest wool cutting. It was found that with increasing cutting speed, the force on the cut of wool decreases. The speed of submission of the machine at strippers with low qualification is 0,3–0,7 m/s; average 0,4–0,8 m/s; high 0,5–1,1 m/s. The width of the comb grip is the main constructive parameter of the shearing machine, which affects its productivity, priority is given to wide-grasping machines having a width of 76,8 mm, with which the main sheep population is processed.
13
Lin, Huang-bin, Shou-gao Tang e Cheng Lan. "Control Parametric Analysis on Improving Park Restoring Force Model and Damage Evaluation of High-Strength Structure". Advances in Materials Science and Engineering 2016 (2016): 1–10. http://dx.doi.org/10.1155/2016/3696418.
Resumo:
In the dynamic time-history analysis of structural elastoplasticity, it is important to develop a universal mathematical model that can describe the force-displacement characteristics for restoring force. By defining three control parameters (stiffness degradation, slip closureγ, energy degradationβ), the Park restoring force mathematical model can simulate various components. In this study, the Park restoring force has been improved by adding two control parameters (energy-based strength degradationβeand ductility-based strength degradationβd). Based on the testing data, the constitutive model is input and 55 numerical models are developed to analyze the effects of various parameters on structural behavior.Conclusion. (1)βhas determinative effect on structural behavior; the effect ofβeis basically consistent with that ofβ;αhas significant effect on shear forces and bending moments;γhas significant effect on displacements and accelerations;βdhas significant effect on shearing forces, acceleration, and total energy consumptions. (2) Based on the classification of four types of damage level, the recommended values forα,γ,β,βe, andβdare presented. (3) Based on the testing data of high-strength columns, the recommended values for the five control parameters of the improved Park restoring force model are presented.
14
Yagita, Ryo, Yohei Abe, Yuma Munesada e Ken-ichiro Mori. "Deformation behaviour in shearing of Ultra-High Strength Steel sheets under insufficient blankholding force". Procedia Manufacturing 50 (2020): 26–31. http://dx.doi.org/10.1016/j.promfg.2020.08.006.
15
Korolczuk-Hejnak, M., e P. Migas. "Analysis of Selected Liquid Steel Viscosity / Analiza Lepkosci Wybranych Gatunków Stali W Stanie Ciekłym". Archives of Metallurgy and Materials 57, n.º 4 (1 de dezembro de 2012): 963–69. http://dx.doi.org/10.2478/v10172-012-0107-3.
Resumo:
This paper presents the results of the rheological analysis of selected grades of steel: 90CrV6, DHQ3, 34CrNiMo. In metallurgical processes, gradient of the dynamic viscosity parameter is an important indicator characterizing the behavior of liquid metal in the industrial aggregates. It affects the processes of heat exchange and mass transport occurring in the existing liquid, solid and gaseous phases. Only a small number of high temperature viscosity measurements is available. This is due to the fact that the experiments are difficult to conduct and due to the general assumption that the molten steel is a liquid exhibiting similarities to Newtonian liquids body. In general liquid metal processes are affected by dynamic forces. Values of the parameters which could be treated as rheological in those real processes are very difficult to measure therefore the influence of the following factors: time of shearing, force value, force direction and shear rate are neglected. The significance of these dynamic parameters seems to be particularly important in the steel continuous casting and thixoforming process. In this work authors analyzed, from the rheological point of view, chosen representative types of steel produced in electric arc furnace. Measurements were taken using a high temperature viscometer FRS1600 in the range of liquidus temperatures as well as above the liquidus for variable shear rates and different time of shearing.
16
Vu, Van-Dam, Thanh-Toan Nguyen, Ngoc-Hung Chu, Quoc-Huy Ngo, Ky-Thanh Ho e Van-Du Nguyen. "Multiresponse Optimization of Cutting Force and Cutting Power in Chopping Agricultural Residues Using Grey-Based Taguchi Method". Agriculture 10, n.º 3 (25 de fevereiro de 2020): 51. http://dx.doi.org/10.3390/agriculture10030051.
Resumo:
Agricultural residues are the most abundant biomass and forage resources. Chopping is a precondition for either use, and reducing the shearing force has been considered as one of the most effective way to save energy. A smaller force can also permit more compact mechanical parts of chopping devices. In several cases, power consumption may be large, even when the shearing force is small, if the corresponding cutting velocity is high. Consequently, it is important to minimize both cutting force and power consumption simultaneously. This paper presents a practical approach to solve the multi-objective optimization problem for chopping processes of corn stalks. Applying the Taguchi design of experiments, a plan of 27 chopping tests was conducted. Based on the grey relational grade analysis and analysis of variance technique, optimum levels as well as the percentage contribution of such parameters were identified. Experimental results showed that the multi-response optimization problem in chopping corn stalks can be effectively addressed through the combination of Taguchi design and grey relational analysis. The results can be expanded for practical applications in design and operation of chopping machines for agricultural residues.
17
Xian, Qingjun, Zhe Wang, Xiaosong Liu, Shaokui Ma e Zhaoran Xiao. "Site Measurement Study on Mechanical Properties of SMW Piles of Building Structures in Sandy Soil Areas". Buildings 12, n.º 10 (19 de outubro de 2022): 1733. http://dx.doi.org/10.3390/buildings12101733.
Resumo:
SMW (soil mixing wall) piles have been widely used in soft soil areas such as Jiangsu, Shanghai, Tianjin and so on, and they have many advantages, such as retaining the structures of foundation pits. In order to promote the application of SMW piles in sandy soil areas such as Henan province, SMW piles were used in a deep foundation pit project of a high-rise building in Zhengzhou. Three SMW piles in the middle area of the foundation pit were selected for site measurement to determine the mechanical properties of SMW piles in sandy soil areas. Several typical test sections were determined along the height of the pile. The vibrating string type of the reinforcement dynamometers were set on the H-shaped steel of each test section, and the stress distribution of the H-shaped steel along the depth of the pit was obtained via testing. The axial force, bending moment and shearing force of the H-shaped steel were further calculated, and the affecting factors and development laws of the internal force distribution of the H-shaped steel were analyzed in detail. The research shows that, at the stage of foundation pit excavation, the overall stress of H-shaped steel increases gradually. The axial force of H-shaped steel in an SMW pile is mainly affected by such factors as the weight of the H-shaped steel, the weight of the crown beam and the first support system, the weight of the breast beam and the second support system, and the frictional resistance of the cemented soil. The bending moment and shearing force of H-shaped steel are mainly affected by such factors as the lateral soil pressure and the concentrated forces of the two support systems. When the foundation pit was excavated to the base, the development of and changes in the law of internal force with regard to the H-shaped steel was analyzed. When the overall internal force of the H-shaped steel is at its maximum, the maximum absolute values in terms of the axial force, bending moment and shearing force are −481 KN, 371 KN·m and 123 KN. In the process of foundation pit excavation and backfilling, the point of contraflexure of the H-shaped steel moves down gradually, and the fixed end of corresponding SMW pile also moves down and stabilizes below the base. These results may provide a reference for the design and construction of SMW piles of building structures in sandy soil areas.
18
Döbrich, Oliver, Thomas Gereke e Chokri Cherif. "A Finite Element Based Approach for the Accurate Determination of the Shear Behaviour of Textiles with the Picture-Frame Shear Test". Key Engineering Materials 554-557 (junho de 2013): 1105–15. http://dx.doi.org/10.4028/www.scientific.net/kem.554-557.1105.
Resumo:
Picture frame shear tests are state of the art for determining the shear force vs. shear angle behaviour for in-plane deformation of most technical textiles, such as woven fabrics. Many publications describe this test and the used picture frames. Benchmark tests showed that the measured shearing behaviour for one sample depends on the picture frame used. The shearing rigidity of most textiles is very small compared to the in-plane tensile stiffness, so slight imperfections on the experimental setup have a significant effect on the measured results. During the picture frame test, wrinkles may form on the sample surface during the motion of the picture frame above a critical shear angle. These wrinkles can be described as local fabric buckling. If forming of wrinkles leads to a lower level of internal energy compared to a further shearing of the fabric, local wrinkles occur due to the principle of least action. Because of this effect, the measured shear force above the first formation of wrinkles is inaccurate for describing the exact shearing behaviour of textiles. Another possibility for measuring the shear force vs. shear angle behaviour is the bias-extension test. Here, higher shear angles can be achieved without the formation of wrinkles. Both methods are compared in this paper for different textile samples. The relationship of the shear angle and the applied shear force is an important mechanical value and one of the most important input parameter in numerical drape simulations. The analysis of wrinkles, which occur during textile draping, demands exact input parameters for the simulation. Most important for the drape simulation of technical high-performance textiles are accurate values for the bending and shear behaviours. This paper presents simulation results of the wrinkling during a picture frame shear test. Results show that the input parameter for the shear rigidity delivered by the picture frame shear test do not exactly reproduce the formed wrinkles and are, therefore, not suitable for an exact drape simulation. The underestimation of the shear force vs. shear angle behaviour will be shown with a finite element simulation model. The adaptation of the picture-frame and bias-extension parameters for a proper use in numerical drape simulations are examined.
19
Tsuruta, Kenji. "Initial Stage of Consolidation of Silicon-Carbide Nanocrystals under Pressure: A Tight-Binding Molecular-Dynamics Study". Journal of Nanomaterials 2011 (2011): 1–6. http://dx.doi.org/10.1155/2011/308495.
Resumo:
Tight-binding molecular-dynamics (TBMDs) simulations are performed to study atomic and electronic structures during high-temperature consolidation processes of nanocrystalline silicon carbide under external pressure. We employ a linear-scaling method (the Fermi-operator expansion method) with a scalable parallel algorithm for efficient calculations of the long time-scale phenomena. The results show that microscopic processes of the consolidation depend strongly on initial orientations of the nanocrystals. It is observed that an orientational rearrangement of the nanocrystals initially misaligned is induced by an instantaneous shearing force between nanocrystals, whereas the aligned system undergoes densification without shearing. Analysis on an effective-charge distribution and an average bond-order distribution reveals electronic-structure evolutions during these processes.
20
Sheu, Jinn Jong, Dong Mei Xu e Chin Wei Liu. "Cutting Force and Tool Deflection Predictions for High Speed Machining of Hard to Cut Material". Advanced Materials Research 154-155 (outubro de 2010): 1157–64. http://dx.doi.org/10.4028/www.scientific.net/amr.154-155.1157.
Resumo:
The dimension accuracy and the too life are the major issues of the machining of hard-to-cut materials. To fulfill the requirements of accuracy and tool life needs not only well planning of cutting path but also the proper cutting conditions of cutters. The vibration and deflection of cutters caused by poor selection of cutting conditions can be predicted using models of cutting force and tool deflection. In this paper, a cutting force model considering the effect of tool helical angle and a cantilever beam model of tool deflection were proposed for the high speed machining of hard-to-cut material SKD11. The shearing force, the plowing forces, and the helical angle of cutters are considered in the elemental force model. The material of workpiece, SKD11, studied in this paper is commonly used for the die and mold industries. The cutting constants of the proposed force model are determined via the cutting experiments carried out on a high speed machining center. A dynamometer and a high frequency data acquisition system were used to measure the x-, y-, and z-direction cutting forces. The obtained cutting constants were used to predict the cutting forces and compared with the results obtained from the cutting experiment of verification using cutters with different helical angles. The theoretical and the experimental cutting forces in the x-, y-, and z- direction are in good agreement using flat cutters with 30 and 45 degrees of helical angle. The dimension deviations of the cut surface in the cutting experiment case of tool deflection were measured using a touch probe and an infrared receiver installed on the machining center. The measured average dimension deviation, 0.163mm, is close to the predicted tool deflection, 0.153mm, using the proposed cantilever beam model. The comparisons of the cutting forces and the average of the cut surface dimension deviation are in good agreement and verify the proposed cutting force and the tool deflection models are feasible and useful.
21
Li, Mengtian, Jun Zou, Wengjuan Wu, Mingming Shi, Bobo Yang, Wenbo Li e Bin Guo. "Effect of Different Welding Methods on Flip-Chip LED (FC-LED) Filament Properties". Applied Sciences 8, n.º 11 (15 de novembro de 2018): 2254. http://dx.doi.org/10.3390/app8112254.
Resumo:
This paper investigates the effect of two different welding methods, direct welding (DW) and vacuum furnace welding (VFW), on flip-chip light-emitting diode (FC-LED) filament properties. Shearing force, SEM, steady-state voltage, steady-state luminous flux, and change of photoelectric performance with aging time were employed to characterize the differences in filament properties between the two welding methods. The shearing test revealed that the average shearing force of the VFW group was higher than that of the DW group, but the two groups followed the standard. Furthermore, the microstructure of the VFW group fault was more smoother, and the voids were fewer and smaller based on the SEM test results. The steady-state voltage and luminous flux revealed that the VFW group had a more concentrated voltage and a higher luminous flux. The aging data revealed that the steady-state voltage change rate of both groups was not very different, and both luminous flux maintenance rates of the VFW group were higher than those of the DW group, but all were within the standard range. In conclusion, if there is a higher requirement for filament in a practical application, such as the filament is connected in series or in parallel and needs a higher luminous flux, it can be welded using vacuum furnace welding. If the focus is on production efficiency and the high performance of filaments is not required, direct welding can be used.
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Wang, Zhi Wei, Ya Long Wang e Dong Dong Zhang. "Optimization on Parameters of Resistance Spot Welding Process for Galvanized Steel Plate". Advanced Materials Research 658 (janeiro de 2013): 178–81. http://dx.doi.org/10.4028/www.scientific.net/amr.658.178.
Resumo:
In order to research welding technology of DX51D+Z cold rolled galvanized steel, using multivariate nonlinear regression orthogonal combination design method, adopted the shear load as quality indicators, counted welding current, electrode force, welding time, squeeze time and the interaction of them as factors, to built the nonlinear regression models, by adopting this model to forecast shearing load. The result shows that this model has high forecast precision.
23
Wang, Zhi Wei, Ya Long Wang e Dong Dong Zhang. "The Multivariate Nonlinear Regression Model of Zincificated Steel Resistance Spot". Advanced Materials Research 664 (fevereiro de 2013): 825–29. http://dx.doi.org/10.4028/www.scientific.net/amr.664.825.
Resumo:
In order to research welding technology of DX51D+Z cold rolled galvanized steel, using multivariate nonlinear regression orthogonal combination design method, adopted the shear load as quality indicators, counted welding current, electrode force, welding time, squeeze time and the interaction of them as factors, to built the nonlinear regression models, by adopting this model to forecast shearing load. The result shows that this model has high forecast precision.
24
Yang, Shu Cai, Bin Jiang, H. Y. Li, M. L. Zheng e S. J. Wang. "Cutting Thickness of High Speed Ball-End Milling Hardened Steel". Advanced Materials Research 426 (janeiro de 2012): 24–27. http://dx.doi.org/10.4028/www.scientific.net/amr.426.24.
Resumo:
In order to solve the problem of machined surface damage and machining efficiency decline that caused by the decrease of effective cutting thickness in high speed ball-end milling hardened steel, using high speed cutting adiabatic shearing model, analyzed the adiabatic shearing deformation on hardened steel, and proposed the criterion of chip separating position. Analyzed the force in the transformation process from cutting to plowing, the influence of cutter deformation on cutting thickness was studied, and established the minimum cutting thickness model. Having done finite element analysis of cutter and experiment of high speed milling hardened steel, the validity of the minimum cutting thickness model was proved. The results show that cutting thickness changes from small to large, and then from large to small under the influence of cutting trajectory and tool edge radius. The deformation of cutter leads to the increase of the minimum cutting thickness, and further enhances chip thickness thinning effect. High feed can compensate cutting thickness thinning and the minimum cutting thickness model provides an effective way to restrain the damage of machined surface and cutter caused by cutter plowing.
25
Kondo, Keita, Keisuke Kido e Toshiyuki Niwa. "Spheronization mechanism of pharmaceutical material crystals processed by extremely high shearing force using a mechanical powder processor". European Journal of Pharmaceutics and Biopharmaceutics 107 (outubro de 2016): 7–15. http://dx.doi.org/10.1016/j.ejpb.2016.06.021.
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Zhang, Kehong, Yuhang Su e Hui Xiao. "Preparation and characterization of nanofibrillated cellulose from waste sugarcane bagasse by mechanical force". BioResources 15, n.º 3 (9 de julho de 2020): 6636–47. http://dx.doi.org/10.15376/biores.15.3.6636-6647.
Resumo:
The effect of different mechanical force application methods was investigated relative to the structure and properties of nanofibrillated cellulose (NFC) from sugarcane bagasse. The NFC was prepared by grinding, high pressure homogenization, and ultrasonication with chemical pretreatment. Fiber morphology, crystalline, chemical structures, and tensile property were analyzed to reveal the mechanisms of NFC production behind different mechanical treatments. The results showed that compared with grinding treatment, high pressure homogenization and ultrasonic treatment can obviously increase the aspect ratio and size uniformity of NFC. Ultrasonic treatment gave the best results. The combination of grinding, high pressure homogenization, and ultrasonic treatment resulted in NFC with the average diameter of 23.18 nm. With the shearing action of grinding, high pressure homogenization, and ultrasonic treatment, the mechanical properties, crystallinity and thermal stability of NFC were gradually enhanced. This results demonstrated that a very low-value agricultural waste product can be easily converted to a high performance nanocomposite with tensile strength of 153.6 MPa and strain at break of 8.83%.
27
Qian, Fei, Hai Jun Wu, Feng Lei Huang, Ai Guo Pi e Xiu Fang Ma. "Projectile Mass Loss Model Using the Coefficient of Friction for High-Speed Penetration into Concrete". Applied Mechanics and Materials 566 (junho de 2014): 365–70. http://dx.doi.org/10.4028/www.scientific.net/amm.566.365.
Resumo:
In this paper, a model of the friction coefficient in the high-speed penetration process has been used, which considers the micro-asperities of the projectile surface, the adiabatic shearing and the heat conduction on the nose of projectile. It also considers that the coefficient of friction is a function of the sliding velocity. Then, an analytical model of mass loss based on the coefficient of friction and the revised dynamic spherical cavity expansion theory of the concrete material is constructed. An analytical estimate for the work done by friction force in the penetration could be calculated and the evaluation of mass loss of projectile could also be calculated by the heat translated from the work done by friction force. Finally, a comparative analysis between the calculated data and the experimental data of mass loss is done.
28
You, Qing, Yongchun Tang, Caili Dai, Mingwei Zhao e Fulin Zhao. "A Study on the Morphology of a Dispersed Particle Gel Used as a Profile Control Agent for Improved Oil Recovery". Journal of Chemistry 2014 (2014): 1–9. http://dx.doi.org/10.1155/2014/150256.
Resumo:
To achieve in-depth profile control of injection water and improve oil recovery, a new profile control agent, termed as dispersed particle gel (DPG), has been developed and reported. In this paper, the morphology of DPG and the factors that influence its morphology are systematically investigated using atomic force microscopy (AFM). The AFM studies show that DPG is composed of small pseudospherical particles and that their sizes can be controlled by adjusting the shearing rate, the initial polymer mass concentration, and the salinity. Dynamic light scattering (DLS) is used to study the effects of the initial polymer mass concentration, the shearing rate, the salinity, and the high-temperature aging on the particle size of DPG. The aggregation ability of DPG is explained using the DLVO theory and space stability theory. This work provides a scientific basis and technical support for the formula design of DPG and its application in the oil and gas field.
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Murakami, Katsuhide, Masato Ishii, Kentaroh Miyazaki e Yasuhiro Tsuneki. "Proposal for an Efficient Damping System for High-Rise Buildings in Major Earthquakes". Journal of Disaster Research 11, n.º 1 (1 de fevereiro de 2016): 106–17. http://dx.doi.org/10.20965/jdr.2016.p0106.
Resumo:
Recent vibration resistant designs for buildings in Japan often adopt a vibration control structure with dampers arranged in the framework. Generally, the dampers are arranged in the building’s core in a geometry that works most effectively to protect against story shearing deformation. It is already known, however, that the above-mentioned arrangement of dampers does not provide good damping effects for the upper stories of high-rise buildings with large aspect ratios, because the protection mechanism is designed to decrease the shearing deformation components of the building’s horizontal deformation caused by its horizontal loads. A new type of dampers, called force-restricted tuned viscous mass dampers (FRTVMD), has been recently developed for such circumstances, amplifying the deformation of viscous dampers with their tuned mass effects. This paper, therefore, first presents a tuned mass damper (TMD) system, effective for high-rise buildings with large aspect ratios against great earthquakes, and then proposes a new vibration control structural system capable of generating better damping effects with FRTVMD. In addition, we review its characteristics and effects by analyzing its vibration response, as well as verify that a combined use of such vibration control structural systems will generate far greater damping effects than an individual system.
30
Nakayama, Noboru, Hayato Inoue, Hideharu Kusunoki, Masaomi Horita, Yoshitaka Kumeda e Keishi Nakamura. "Effect of Shearing Distance on Mechanical and Electrical Properties for Cu-11Mn-4Ni Thin Plate Formed by Compression Shearing Method at Room Temperature". Materials Science Forum 941 (dezembro de 2018): 1517–22. http://dx.doi.org/10.4028/www.scientific.net/msf.941.1517.
Resumo:
ince the temperature coefficient of resistance of Manganin (Cu-12Mn-2Ni) is extremely small, Manganin plate are used for resistors, especially shunts for current sensing.Generally, the melting and casting is used as a method to make an alloy such as Manganin. Further, the Manganin used as resistive material is produced by rolling after casting. Since such manufacturing processes have heating steps, long molding time is necessary and temperature control is important.In recent years, Cu-11Mn-4Ni powder has been developed. If manganin plate can be produced directly from alloy powder, simplification of the manufacturing process can be expected. A powder metallurgy is used as a method of solidifying and shaping the alloy powder. However many pores are generated in the sample because of using a binder. Therefore, the resistance value of the alloy fabricated through the method may not be stable.The Compression Shearing Method at Room Temperature (COSME-RT) is one of solutions to achieve the high density forming. In COSME-RT alloy powders are simultaneously loaded by a shearing force and a compressive stress in air at room temperature to form a plate. In the process, temperature control is unnecessary and the manufacturing time becomes shorter.In the present study, the fabrication of Cu-11Mn-4Ni plate is carried out by compression shearing method at room temperature and mechanical and electrical properties of the plate are evaluated.
31
Furmanov, D. V., N. N. Klochko e T. A. Krasnobaev. "Testing of equipment for removing reinforced concrete pile caps". Russian Automobile and Highway Industry Journal 21, n.º 1 (11 de março de 2024): 38–46. http://dx.doi.org/10.26518/2071-7296-2024-21-1-38-46.
Resumo:
Introduction. The article discusses the requirements for equipment for removing pile caps of reinforced concrete piles. The machines produced nowadays have excessive power and strength parameters which has been noted and proved experimentally.Materials and methods. Using a prototype of operational equipment on the different piles of different cross-section the force parameters of the working process, the character of development of cutting resistance forces in the cycle were investigated.Results. The stick-slip nature of cutting resistance forces and then a sharp drop of these forces on the whole area of theoscillogram indicates the brittle character of the pile fracture. It is also noted that the dependence of head shearing resistance forces on the height of the pile cap is linear. Technological and constructive features of the new equipment were investigated. High productivity of the machine as a whole was shown.Discussion and conclusion. Based on the results of the tests, the authors concluded that further work on the study of the working process of removal of reinforced concrete pile caps is reasonable.
32
Hidalgo-Tufiño, Lizbeth, Anais Adauto e Carmen Velezmoro. "Speed shear rate impact on the properties of OSA-modified potato starch". Scientia Agropecuaria 14, n.º 1 (22 de março de 2023): 117–25. http://dx.doi.org/10.17268/sci.agropecu.2023.011.
Resumo:
The reaction between starch granules and octenyl succinic anhydride (OSA) is regularly retarded due to the low breakthrough of large oily OSA droplets into starch granules in an aqueous reaction system. Furthermore, high-speed shearing is widely used in the food industry, demanding high shear, cavitation, and collision force. In this sense, high-speed shearing could reduce the size of OSA droplets and promote a more homogeneous distribution of groups in the starch granule. The aim of this study was to evaluate the impact of OSA potato starch synthesis assisted by high-speed shear on structure (SEM and FTIR), gelatinization, rheology, and emulsifying activity (ES and AS) was investigated. The results showed a gradual increase in DS proportional to the applied speed. Likewise, the OSA starches showed a slight alteration in the shape of the granules (SEM), and FT-IR spectroscopy showed a characteristic absorption of the ester carbonyl groups in the OSA starch at 1724 cm-1. The high-speed shear-treated starches exhibited a significant change in the reduction of the initial gelatinization temperature, although not in the enthalpy. All the gels presented rheology adjusted to the Herschel-Bulkley model with variations in the initial shear stress. Changes in the viscoelastic behavior are proportional to the shear rate detected. High-speed shear treatment did not show a significant effect on emulsion stability (ES) and emulsion activity (EA). Consequently, applying high shear rates allows having OSA starches with different uses.
33
van der Veen, C. J., e I. M. Whillans. "Force Budget: Numerical Methods and Application to Two-Dimensional Flow Along the Byrd Station Strain Network, West Antarctica (Abstract)". Annals of Glaciology 11 (1988): 210. http://dx.doi.org/10.3189/s0260305500006716.
Resumo:
Using the partitioning of full stresses into resistive and lithostatic parts, force balance for plane flow is expressed in terms of strain-rates and a vertical coordinate scaled to the ice thickness. The balance equation and constitutive relation can then be used to calculate stresses through a vertical section of a glacier. Because the flow law is highly non-linear, these calculations are done numerically. Starting at the surface, the force-balance equation is solved by using measured surface velocities to calculate vertical shearing, and this yields velocities at a depth just below the surface. These velocities are used to compute vertical shearing at that depth, from which velocities at the next deeper layer follow. In this way, going progressively downward, velocities and stresses are calculated throughout a section of a glacier.The theory for calculating resistive stresses and velocities in a glacier is applied to the Byrd Station Strain Network. Large longitudinal variations in basal drag and in sliding velocity occur and this result is little affected by errors in the input data or by uncertainties in the constitutive relation for ice. The basal drag is usually equal to the driving stress to within 10–20%, and both vary by a factor of about 2 along the strain network. Sites of high drag and little sliding are not always correlated with basal highs, indicating that some process (for example, complex bed drainage) is controlling the friction at the bed of the West Antarctic ice sheet.
34
van der Veen, C. J., e I. M. Whillans. "Force Budget: Numerical Methods and Application to Two-Dimensional Flow Along the Byrd Station Strain Network, West Antarctica (Abstract)". Annals of Glaciology 11 (1988): 210. http://dx.doi.org/10.1017/s0260305500006716.
Resumo:
Using the partitioning of full stresses into resistive and lithostatic parts, force balance for plane flow is expressed in terms of strain-rates and a vertical coordinate scaled to the ice thickness. The balance equation and constitutive relation can then be used to calculate stresses through a vertical section of a glacier. Because the flow law is highly non-linear, these calculations are done numerically. Starting at the surface, the force-balance equation is solved by using measured surface velocities to calculate vertical shearing, and this yields velocities at a depth just below the surface. These velocities are used to compute vertical shearing at that depth, from which velocities at the next deeper layer follow. In this way, going progressively downward, velocities and stresses are calculated throughout a section of a glacier. The theory for calculating resistive stresses and velocities in a glacier is applied to the Byrd Station Strain Network. Large longitudinal variations in basal drag and in sliding velocity occur and this result is little affected by errors in the input data or by uncertainties in the constitutive relation for ice. The basal drag is usually equal to the driving stress to within 10–20%, and both vary by a factor of about 2 along the strain network. Sites of high drag and little sliding are not always correlated with basal highs, indicating that some process (for example, complex bed drainage) is controlling the friction at the bed of the West Antarctic ice sheet.
35
Yan, Xiaoyu, Wei Wang, Xiaojun Liu, Jimin Xu, Lihong Zhu e Bingxun Yang. "Using FEM to study the frictional instability induced by third-body particles confined in frictional interface". Industrial Lubrication and Tribology 72, n.º 10 (1 de junho de 2020): 1239–44. http://dx.doi.org/10.1108/ilt-12-2019-0544.
Resumo:
Purpose A finite element method (FEM) model of the frictional behavior of two rough surfaces with a group of third-body particles confined by the surface asperities is established. By monitoring the stress distribution, friction force and the displacement of the surfaces, how the frictional instability is induced by these particles is studied. This modeling job aims to explore the relation between the meso-scale behavior and the macro-scale frictional behavior of these particles. Design/methodology/approach By using FEM, a 2D model of two frictional rough surfaces with a group of elastic or elasto-plastic particles confined by surface asperities is established. The Mises stress, macro friction force and displacements of elements are monitored during compressing and shearing steps. Findings The macro friction coefficient is more stable under higher pressure and smaller under higher shearing speed. The dilatancy of the interface is caused by the elevation effect of the particles sheared on the peak of the lower surface, particles collision and third body supporting. The combined effect of particles motion and surface–surface contact will induce high-frequency displacements of surface units in restricted direction. Originality/value Previous studies about third-body tribology are mainly concentrated on the frictional behavior with large number of particles distributed homogeneously across the interface, but this paper focuses on the behavior of third-body particles confined by surface asperities. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-12-2019-0544/
36
Schulz, Volker Paul, Nima Abbaspour, Tobias Baumeister e Thorsten Röder. "Lattice-Boltzmann Simulation and Experimental Validation of a Microfluidic T-Junction for Slug Flow Generation". ChemEngineering 3, n.º 2 (5 de maio de 2019): 48. http://dx.doi.org/10.3390/chemengineering3020048.
Resumo:
We investigate the interaction of two immiscible fluids in a head-on device geometry, where both fluids are streaming opposite to each other. The simulations are based on the two-dimensional (2D) lattice Boltzmann method (LBM) using the Rothman and Keller (RK) model. We validate the LBM code with several benchmarks such as the bubble test, static contact angle, and layered flow. For the first time, we simulate a head-on device by forcing periodicity and a volume force to induce the flow. From low to high flow rates, three main flow patterns are observed in the head-on device, which are dripping-squeezing, jetting-shearing, and threading. In the squeezing regime, the flow is steady and the droplets are equal. The jetting-shearing flow is not as stable as dripping-squeezing. Moreover, the formation of droplets is shifted downstream into the main channel. The last flow form is threading, in which the immiscible fluids flow parallel downstream to the outlet. In contrast to other studies, we select larger microfluidic channels with 1-mm channel width to achieve relatively high volumetric fluxes as used in chemical synthesis reactors. Consequently, the capillary number of the flow regimes is smaller than 10−5. In conclusion, the simulation compares well to experimental data.
37
Modric-Sahbazovic, Almedina, Mirjana Novakovic, Veljko Djokic, Izet Gazdic, Natasa Bibic e Zlatko Rakocevic. "Formation of a large-area monolayer of polystyrene film via the spin-coating method". Nuclear Technology and Radiation Protection 33, n.º 3 (2018): 246–51. http://dx.doi.org/10.2298/ntrp1803246m.
Resumo:
The self-assembly methods, an inexpensive and high throughput technique capable of producing nanostructure arrays, relies on the formation on a monolayer of self-assembled nanospheres. This paper reports on the formation of large-areas monolayer polystyrene particles ~150 nm in diameter onto monocrystalline Si (100) substrates by using the spin-coating method. In this method, the quality of the deposited monolayer is determined by the balance between spinning and solvent evaporation, accounted by two different forces, the centrifugal force and viscous shearing force, and their interplay. The key process parameters which influence the deposition process and determine the properties of polystyrene monolayers such as the spinning rate, time and concentration of PS particles in the solution were studied. By varying the experimental conditions in different steps the films quality can be easily improved and the optimized experimental parameters were achieved. A homogenous and well-ordered PS monolayer with a high surface coverage of ~94 % was formed on a large-area substrate of 1 cm ?1 cm at specific conditions of a 2000 rpm spinning rate, 2 wt. % polystyrene solution concentration and 210 s duration of the spinning process. We conclude that this method can be useful in a variety of applications since it offers a stable and controllable approach to the fabrication of monolayer polystyrene films on a large-scale.
38
Li, Shu Kun, Lu Hai Li, Xian Leng, Wen Bo Li, Xu Wei Hu e Wei Wei Li. "Dispersion Investigation on Cobalt Blue in Organic Solvent". Advanced Materials Research 311-313 (agosto de 2011): 521–25. http://dx.doi.org/10.4028/www.scientific.net/amr.311-313.521.
Resumo:
The performance of the dispersion of cobalt blue in organic solvent is studied. The influence of dispersant (type & dosage), pH value, and other dispersion parameters on the stability of cobalt blue dispersion system is tested which shows good stability and excellent dispersion performance with diethylamide glycol ether the solvent, complex formulation (M (KH550): M (KH560): M (A-842) = 1:1:2) the dispersant and 7 the pH value. The characteristics of dispersion system are evaluated through sedimentation experiment and measurement of article size distribution. The most steady dispersion system is formed through high speed shearing force and the size of cobalt blue in this system is about 300nm.
39
Jamkamon, Kamonpong, Keiji Yamada, Katsuhiko Sekiya e Ryutaro Tanaka. "Effects of Preheating Temperature at Primary Shear Zone in Laser Assisted Milling Process". Key Engineering Materials 825 (outubro de 2019): 45–50. http://dx.doi.org/10.4028/www.scientific.net/kem.825.45.
Resumo:
In this paper, preheating temperature was investigated for the laser assisted machining (LAM) of Inconel 718 under different conditions for the milling test. The experimental results show that the requirement of laser power for the particularly preheating temperature proportionally increased with the table speed. The resultant cutting force for sufficient shearing work material in LAM was lower than conventional machining (CM) approximately 11, 21 and 28% for the cutting speed of 30, 50 and 75 m/min, respectively. The tool wear in LAM could be improved at relatively high cutting speed of 75 m/min and the hardness of machined surface in LAM was slightly higher than CM.
40
Liu, Hongliang, Xun Wu, Jiaxuan Huang, Xibo Shao, Pei Wang, Guanyu Deng e Long Wang. "Influence of Concentration of Sodium Metasilicate and Descaling on the High Temperature Lubricating Effects Evaluated by Hot Rolling Mill". Lubricants 11, n.º 8 (18 de agosto de 2023): 352. http://dx.doi.org/10.3390/lubricants11080352.
Resumo:
Lubricant is vital to improve energy efficiency and workpiece durability for the moving counterpart. High-temperature lubricants are important for the hot rolling process to reduce the rolling force and protect the roller and the strips. The current paper concerns eco-friendly sodium metasilicate as a high-temperature lubricant. A hot rolling mill is employed to evaluate the lubrication effect of sodium metasilicate. The influence of crucial factors of concentration of lubricant and descaling is discussed; the rolled surface was analyzed by scanning electron microscopy, energy dispersive spectroscopy, and 3D profilometer. The results depict that the sodium metasilicate can reduce the rolling force by about 7.8% when the concentration of sodium metasilicate is 18% and above, and descaling of the hot stripe makes the lubrication effect more effective, which can reach a 12.7% reduction in the rolling force. This lubrication is attributed to the formed melts of the sodium silicate layer that offers an easy shearing interface. For the un-descaled samples, the lubricant will be compacted and mixed with the oxide scale, and weakens the lubrication effect. This work suggests that sodium metasilicate can be a high-temperature lubricant for hot rolling; descaling is vital, not only for the quality of the product but also for the efficiency of the lubricant. This work will also be useful for the concentration selection of glass lubricant.
41
Chen, Chao, Huiyang Zhang, Hao Peng, Xiangkun Ran e Qing Pan. "Investigation of the Restored Joint for Aluminum Alloy". Metals 10, n.º 1 (7 de janeiro de 2020): 97. http://dx.doi.org/10.3390/met10010097.
Resumo:
In recent years, the mechanical clinching method plays an increasingly important role in the building of thin-walled structures. The clinched joint can be employed to join the lightweight materials. Compared with other joining methods, the clinched joint has better mechanical behavior. However, the clinched joint may be deformed during use when it bears a high shear force. In this research, a process to join aluminum alloy and restore deformed joint was proposed and investigated. The clinched joint was deformed in the deforming process. Then, a customized rivet and two flat restoring tools were utilized for restoring the deformed joint to join aluminum alloy. Different restoring forces such as 45, 40, 35, 30, 25, and 20 kN were employed to produce diverse restored joints. Some shearing tests on the restored joint were utilized for understanding joint material flow, mode of failure, thickness of neck, shear strength, and absorption of energy. The thickness of neck can be increased in restoring process, which contributes to improve the shear strength. The rivet embedded in a pit also helps restored joint bear shear force, so all of the restored joints have higher absorption of energy and shear strength than the clinched joints. The restoring process effectively restores the deformed joint to obtain better mechanical behavior.
42
Zhang, Shu Yun, Guo Liang Bai e Lai Shun Zhao. "Research on Mechanical Behaviors of Composite Frame and Reinforced Concrete Core Hybrid Structures in High-Rise Buildings". Advanced Materials Research 163-167 (dezembro de 2010): 2056–62. http://dx.doi.org/10.4028/www.scientific.net/amr.163-167.2056.
Resumo:
For mechanical behaviors of composite frame and reinforced concrete core hybrid Structures in high-rise buildings, the three-dimension finite element models were established, modal analysis and elastic time-history analysis were finished, the cooperative work mechanism between frame and core was researched, the dynamic characteristics and seismic response of the hybrid structures under different connection type were studied. the results indicate that the stiffness characteristic of the hybrid structures should be taken between 1 to 2 so that two sub-structure can reasonably afford the internal force, the connection between frame and core bring differences in mode shape and natural vibration periods, the natural vibration periods of hinged model are greater than periods of rigid model, the mode shapes with mainly floor vibration are more likely to appear in hinged model, the connection would lead to significant changes in the deformation and distribution of inner force, the axial force of frame columns would significantly increase for the rigid connection, the shear and bending moment of frame columns would increase for the hinged connection, it was proposed that the hybrid structures should be separately analyzed with hinge model and rigid model for ensuring the frame columns have sufficient capacity of the shearing and bending both.
43
Carpenter, Chris. "Low-Force Shear Blades Developed for High-Strength Coiled Tubing". Journal of Petroleum Technology 73, n.º 06 (1 de junho de 2021): 42–43. http://dx.doi.org/10.2118/0621-0042-jpt.
Resumo:
This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 204403, “Development of Low-Force Shear Blades for High-Strength Coiled Tubing,” by Scott Sherman, Nexus Energy Technologies, prepared for the 2021 SPE/ICoTA Virtual Well Intervention Conference, 22–25 March. The paper has not been peer reviewed. As coiled tubing (CT) grades have evolved during the past 20 years and wall thicknesses have increased, the resulting force required to shear coil has more than doubled. An industry need existed to develop a shear blade for blowout preventers (BOPs) that could cut high-strength CT using legacy pressure-control equipment already in use. The paper describes the iterative process of development of a novel shear blade able to cut high-strength CT with 50% of the normal shear force. Objective The objective of the work detailed in the complete paper was to develop a novel CT-shearing system capable of cutting high-strength heavy-wall CT with reduced hydraulic pressures. Considering that CT will continue to evolve in terms of yield strength, the goal of the study was to future-proof BOPs wherever possible to protect customers from the liability of obsolete equipment. The authors write that, ultimately, BOPs will need to cut 175-grade CT strings with a 7-mm wall thickness with 103 MPa of wellbore pressure and less than 17.2 MPa hydraulic pressure. Development Process Initially, the following five options were considered: - Larger-diameter cylinders. This seemingly simple option, which would generate more shear force, was ruled out because the implementation would not be backward-compatible with existing well-control equipment and the larger cylinder volume would result in slower cycle times. - Boosted actuators. These could double shear force while maintaining piston diameter. While this solution is simple, theoretically, these actuators require twice as much hydraulic fluid from the accumulator to function. This results in a closing time that is nearly double that of a nonboosted actuator. - Pressure-balanced actuators. With this option, hydraulic forces would not need to overcome the forces related to wellbore pressure in addition to providing sufficient force to shear CT. These actuators do increase the amount of shear force available to cut CT when used on high-pressure wells. However, they increase complexity, cost, and weight and could result in trapped wellbore fluids within the actuator that could lead to corrosion-related issues. - Increasing hydraulic pressure to a given set of rams using a pressure multiplier for the shear rams or a similar system. This solution was deemed unsuitable because the hydraulics of most BOPs are designed for 150% of their rated pressure. Doubling the hydraulic pressure available to the BOP could damage the hydraulic cylinders and associated actuators, resulting in a catastrophic well-control situation. - Modifying shear blade geometry to reduce the shear force needed to cut CT using existing equipment. This was selected as the most-logical approach because the modified shear blades could be retrofitted into existing BOPs. Furthermore, this solution would not require modification to existing wellsite equipment such as accumulator skids and would not increase the weight or size of the BOP stack.
44
Veenaas, Stefan, e Frank Vollertsen. "High Speed Joining by Laser Shock Forming". Advanced Materials Research 966-967 (junho de 2014): 597–606. http://dx.doi.org/10.4028/www.scientific.net/amr.966-967.597.
Resumo:
Due to an ongoing trend of function compaction miniaturization gets more and more important in industrial production. This makes hybrid joints under various conditions also in the micro range necessary. Existing joining solutions often have restrictions due to the principle of joining. Thus in this article a new high speed forming method for the micro range is shown, which is based on plastic deformation by laser induced shockwaves. First of all it is shown how metal sheet-sheet joints can be realized with this method. With the produced joints tensile tests are carried out, where a maximum shearing force of 26.7 N could be achieved. For a detailed process understanding, the near-field of the acting pressure of the TEA-CO2-laser induced shockwaves is measured. Moreover it is determined that the ignition point of the TEA-CO2-laser induced plasma out of aluminum is about 8 mm above the surface.
45
Nurul Fatin, M. R., A. B. Mohd Hadzley, Raja Abdullah Raja Izamshah e M. A. Amrand. "An Experimental Study of Wear Mechanism on High Speed Machining of FC300 Gray Cast Iron Using TiAlN Coated Carbide Cutting Tool". Applied Mechanics and Materials 761 (maio de 2015): 257–61. http://dx.doi.org/10.4028/www.scientific.net/amm.761.257.
Resumo:
This paper presents an experimental study of wear mechanism on high speed milling of FC300 gray cast iron using TiAlN coated carbide cutting tool. The experiment was carried out under dry cutting condition with different cutting speed (95-143m/min) and feed rate (4000-7000 mm/min). The cutting tool for machining FC300 gray cast iron is a ball nose end mill ø32 mm coated with TiAlN. Wear mechanism was analyzed at VB 0.08mm after 60 minute machining. The flank wear increased when the spindle speed and feed rate increased caused by the generated high shearing force and high cutting temperature. The dominant wear mechanisms appear to be the abrasion, adhesion, chipping and delaminating of coating at the contact surface of cutting tool. Formation of built-up edge (BUE) was evidence for most of the cutting trials.
46
Zhou, Chun Li, Wei Chen e Jin Kun Sun. "Experimental Study of LRB Energy Dissipation Walls and its Engineering Example Study". Applied Mechanics and Materials 405-408 (setembro de 2013): 2010–14. http://dx.doi.org/10.4028/www.scientific.net/amm.405-408.2010.
Resumo:
LRB energy dissipation wall is a type of energy dissipation device for building structures. According to the results of an quasi-static test, structure with LRB energy dissipation wall shows a stronger energy dissipation capacity and a better seismic performance than the normal frame-shear wall structure. This paper also introduces the applications technology of LRB energy dissipation wall in High-level framework structure. According to the dynamic property analysis of a three-dimensional finite element model which was built by the finite element analysis software ETABS, LRB energy dissipation wall can effectively prolong the natural vibration period of high-rise frame structure and significantly reduce the maximum acceleration, shearing force and horizontal displacement in different floors to make the variation more smooth which is important the to the energy dissipation and earthquake mitigation.
47
Golewski, Grzegorz L., e Tomasz Sadowski. "Experimental Investigation and Numerical Modeling Fracture Processes under Mode II in Concrete Composites Containing Fly-Ash Additive at early Age". Solid State Phenomena 188 (maio de 2012): 158–63. http://dx.doi.org/10.4028/www.scientific.net/ssp.188.158.
Resumo:
Mode II fracture analysis is especially important. This mode is vital in relation to concrete, due to its relatively low shearing strength and high sensitivity to such type of stress. Nowadays, the structural concretes containing an additives of fly-ash are quite commonly used in the construction industry. Initial cracks origin and development research was carried out using samples for three concrete mixtures: concrete without silica fly-ash (FA), concrete with 20% and concrete with 30% FA additive. 150x150x150 concrete cube with two initial cracks was used as a test sample. Experimental investigation under Mode II fracture was carried out in concrete composites at early age (after 3, 7, 14 and 21 days). X-FEM method enables observation of defect initiation and development, there is no need to input the original conditions. Calculations used peak principal stress criterion. Most calculations coincide with results of experimental research. There was a convergence of: cracks shapes, FQ critical force values, force - displacement graphs.
48
Chen, Hui Qiang, e Bo Ming Tang. "Study on Properties of Thin Layer Skid-Resistance Material in Tunnel Paving". Advanced Materials Research 150-151 (outubro de 2010): 969–74. http://dx.doi.org/10.4028/www.scientific.net/amr.150-151.969.
Resumo:
In order to reduce traffic accidents in tunnel, a type of new road material with excellent skid resistance and multicolour which was abbreviated to TSRM was studied in this paper, and its properties were analyzed and characterized by means of testing its cohesive force, shearing strength, water stability, chemistry stability and skid-resistance on the basis of the former studies. Based on large amount of indoor tests, technical standards for components of TSRM were put forward. The curing mechanism of TSRM was probed into in this paper. The results verified that the comprehensive properties of TSRM were excellent, and it has a high friction factor and good texture depth. With the result that TSRM was fit for tunnel paving.
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Wang, Y. H., e S. C. Leung. "A particulate-scale investigation of cemented sand behavior". Canadian Geotechnical Journal 45, n.º 1 (janeiro de 2008): 29–44. http://dx.doi.org/10.1139/t07-070.
Resumo:
In this paper, triaxial tests and numerical simulations using the discrete element method (DEM) are combined to explore the underlying mechanisms of the unique behavior of artificially cemented sands. The experimental results show that strength enhancement, volumetric dilation, and the shear banding associated failure mode are observed in Portland cement sand; these features become more pronounced with increasing cement content. Different responses are found in gypsum-cemented sand even though both types of cemented sand specimens were prepared under very similar void ratios before shearing. The DEM simulations on the Portland cement sand were carried out under two particular arrangements (i.e., the use of small cementing particles and flexible membrane boundaries). The simulation results reveal that particles in the bonding network jointly share the loading and many micro force-chains associated with cementation are created. Compared with uncemented sand, a more stable and stronger force–chain complex subjected to smaller force concentration is formed in cemented sand, which gives rise to higher strength. Intensive bond breakage, concentrated relative particle movement, column-like force chains, great particle rotation, and high local porosity are found inside the shear band. The bonded clusters remain at large strains to help stabilize the particle arch and therefore to maintain the volumetric dilation.
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Subair, Aysar Hassan, e Ala Nasir Aljorany. "Shaft Resistance of Long (Flexible) Piles Considering Strength Degradation". Journal of Engineering 27, n.º 3 (27 de fevereiro de 2021): 54–66. http://dx.doi.org/10.31026/j.eng.2021.03.04.
Resumo:
Soil-structure frictional resistance is an important parameter in the design of many foundation systems. The soil-structure interface area is responsible for load transferring from the structure to the surrounding soil. The mobilized shaft resistance of axially loaded, long slender pile embedded in dense, dry sand is experimentally and numerically analyzed when subjected to pullout force. Experimental setup including an instrumented model pile while the finite element method is used as a numerical analysis tool. The hypoplasticity model is used to model the soil adjacent to and surrounding the pile by using ABAQUS FEA (6.17.1). The soil-structure interface behavior depends on many factors, but mainly on the interface soil's tendency to contract or dilate under shearing conditions. To investigate this tendency, three piles with different surface roughness and under different confining pressures are used. A dilation behavior is observed in the relation of the average shaft resistance with the axial displacement for piles with rough and medium roughness surfaces, while contraction behavior is noticed when shearing piles with smooth surfaces. A large shear strength degradation of about (10%) reduction in the shaft resistance is observed under low confining pressure compared to a lesser reduction value of about (2%) under high confining pressure. Good agreement is obtained between the experimental and the numerical results.