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1
Hammza, Tariq M., Ehab N. Abas, and Nassear R. Hmoad. "Optimum Design of Journal Bearings Dimensions for Rotating Machines." Engineering and Technology Journal 38, no. 10A (October 25, 2020): 1481–88. http://dx.doi.org/10.30684/etj.v38i10a.1093.
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The values of Many parameters which involve in the design of fluid film journal bearings mainly depend on the bearing applied load when using the conventional design method to design the journal bearings, in this study, as well as applied bearing load, the dynamic response and critical speed have been used to calculate the dimensions of journal bearings. In the field of rotating machine, especially a heavy-duty rotating machines, the critical speed and response are the main parameters that specify bearing dimensions. The bearing aspect ratio (bearing length to bore diameter) and bearing clearance have been determined based on rotor maximum critical speed and minimum response displacement. The analytical solution of rotor Eq. of motion was verified by numerical solution via using ANSYS Mechanical APDL 18.0 and by comparing the numerical solution with the preceding study. The final study results clearly showed that the bearing aspect ratio has little effect on the critical speed, but it has a high effect on the dynamic response also the bearing clearance has little effect on the critical speed and considerable effect on the dynamic response. The study showed that the more accurate values of bearing aspect ratio to make the response of rotor as low as possible are about 0.65 - 1 and bearing percent clearance is about 0.15 - 0.2 for different rotor dimensions.
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Xu, Yuan, Xiao Ping Wang, Juan Cheng, and Dong Wang. "Orthogonal Design Choices Recycled Concrete Load-Bearing Hollow Block." Applied Mechanics and Materials 368-370 (August 2013): 1090–94. http://dx.doi.org/10.4028/www.scientific.net/amm.368-370.1090.
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Study four factors - water consumption , water-cement ratio , recycled fine aggregate replacement ratio of recycled coarse aggregate replacement rate - affect the regularity of the load-bearing hollow block compressive strength of recycled concrete by orthogonal test method , the test showed that , water consumption factors affect the compressive strength of recycled concrete block design with than the emphasis on the control of water consumption . Under the test conditions , the optimum mixture ratio of recycled concrete load-bearing block : water consumption of 160 kg / m 3 , the water cement ratio 0.45 , recycled fine aggregate replacement ratio of 30% recycled coarse aggregate replacement ratio of 30% .
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Huang, Jian, Chaoyang Li, and Bingkui Chen. "Optimization Design of RV Reducer Crankshaft Bearing." Applied Sciences 10, no. 18 (September 18, 2020): 6520. http://dx.doi.org/10.3390/app10186520.
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The crankshaft bearing is the key component of a rotate vector (RV) reducer. However, owing to the harsh working load and restricted available space, the bearing often suffers from fatigue failure. Therefore, this study proposes a novel optimization method for RV reducer crankshaft bearings. A nonlinear constraint optimization model for the design of the bearing considering the crowned roller profile is formulated and is solved by using a crow search algorithm. The goal of the optimization is to maximize the fatigue life of the bearing. The design variables corresponding to the bearing geometry and crowned roller profile are considered. The load working conditions of the bearing and structure of the RV reducer are analyzed. Various constraints, including geometry, lubrication, strength of the bearing, and structure of the RV reducer, are established. Through the optimization design, the optimum crowned roller profile suitable for the working load of the bearing is obtained, and the stress concentration between the roller and raceway is eliminated. Taking the crankshaft bearing of RV-20E and RV-110E type reducers as examples, the bearings were optimized by the proposed method. After optimization, the bearing life of the RV-20E type reducer is increased by 196%, and the bearing life of the RV-110E type reducer is increased by 168%.
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Megson, T. H. G., and G. Hallak. "Optimum Design of Load-Bearing Box Girder Diaphragms having a central support." Thin-Walled Structures 22, no. 3 (January 1995): 203–15. http://dx.doi.org/10.1016/0263-8231(94)00037-z.
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Zhang, Yu Lian, and Hai Zhang. "Optimum Design Study of a Hydraulic Pressure Derrick Based on Stability." Advanced Materials Research 189-193 (February 2011): 1982–85. http://dx.doi.org/10.4028/www.scientific.net/amr.189-193.1982.
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The bearing load is very large when the hydraulic pressure derrick suspends cargo. The hydraulic pressure derrick is a very important component which transfers cargo load to hull. The method of optimization theory based on dual method was transplanted to optimize the hydraulic pressure derrick structure and the optimizing model of the hydraulic pressure derrick was established. The hydraulic pressure derrick structure was optimized under four load cases. The numerical results show that the structure strength and stability of hydraulic pressure derrick are fit.
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Li, Ming, and Li Na Sun. "Optimum Design for Improvement of Roller Bearing Load Distribution in a Medium Scale Mill." Applied Mechanics and Materials 215-216 (November 2012): 54–58. http://dx.doi.org/10.4028/www.scientific.net/amm.215-216.54.
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In roller bearing reformation of a medium scale mill, the micro-dimensional theory of mill is adopted. A new space self-alignment roll system is developed, including a divided base. This ensures the statically determinate of the mill under both light duty and heavy duty conditions. So the load distribution of roller bearing can be improved, and the bearing will have a long life. Since the new roll system began to run, it is in a fine motion until now. The roller bearing has exceeded its specified life. The design aim of service longevity is realized.
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Zhang, Yongbin. "BOUNDARY SLIPPAGE FOR IMPROVING THE LOAD AND FRICTION PERFORMANCE OF A STEP BEARING." Transactions of the Canadian Society for Mechanical Engineering 34, no. 3-4 (September 2010): 373–87. http://dx.doi.org/10.1139/tcsme-2010-0022.
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The present paper proposes a new type of step bearing by specifically modifying the interfacial condition between the fluid film and the bearing surface and introducing the boundary slippage at those interfaces. Analysis for the load-carrying capacity and friction coefficient is presented for this kind of bearing. The comparison of the obtained analytical results with the conventional (no-slippage) step bearing results shows that modifying the interfacial condition and introducing the boundary slippage at the specific bearing surfaces can significantly increase the load-carrying capacity and reduce the friction coefficient of a step bearing. Design guideline, the load-carrying capacity and the friction coefficient are also presented for this bearing at optimum condition which reaches the maximum load-carrying capacity.
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Hattori, T., H. Ohnishi, and M. Taneda. "Optimum Design Technique for Rotating Wheels." Journal of Engineering for Gas Turbines and Power 110, no. 1 (January 1, 1988): 41–44. http://dx.doi.org/10.1115/1.3240084.
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Compressor rotors and turbine rotors are subject to centrifugal and thermal loads. These loads increase proportionally with tip speed, pressure ratio, and gas temperature. On the other hand, the rotor weight must be lessened to improve rotor dynamics and restrict bearing load. Thus, an optimum design technique is required, which offers the lightest possible wheel shape under the stress limit restriction. This paper introduces an optimum design system developed for turbomachinery rotors, and discusses several application results. The sequential linear programming method is used in the optimizing process, and centrifugal and thermal stress analyses of variable thickness rotating wheels are performed using Donath’s method. This system’s validity is confirmed by application to uniform-strength rotating disk problems and comparison with analytical results. This optimum design program is then applied to the design of axial flow compressor wheels.
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Wang, Qingyan, Hongzhong Ma, Shengrang Cao, and Bingyan Chen. "Structure Optimal Design of Electromagnetic Levitation Load Reduction Device for Hydroturbine Generator Set." Mathematical Problems in Engineering 2015 (2015): 1–5. http://dx.doi.org/10.1155/2015/814084.
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Thrust bearing is one part with the highest failure rate in hydroturbine generator set, which is primarily due to heavy axial load. Such heavy load often makes oil film destruction, bearing friction, and even burning. It is necessary to study the load and the reduction method. The dynamic thrust is an important factor to influence the axial load and reduction design of electromagnetic device. Therefore, in the paper, combined with the structure features of vertical turbine, the hydraulic thrust is analyzed accurately. Then, take the turbine model HL-220-LT-550, for instance; the electromagnetic levitation load reduction device is designed, and its mathematical model is built, whose purpose is to minimize excitation loss and total quality under the constraints of installation space, connection layout, and heat dissipation. Particle swarm optimization (PSO) is employed to search for the optimum solution; finally, the result is verified by finite element method (FEM), which demonstrates that the optimized structure is more effective.
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Wang, Ying Jia, Qi Wu Dong, Hong Guo, and Shao Qi Cen. "Performance Analysis of the Rayleigh Step Bearing under the Coexistence State of Fluid with Laminar Flow and Turbulence." Advanced Materials Research 396-398 (November 2011): 886–92. http://dx.doi.org/10.4028/www.scientific.net/amr.396-398.886.
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In the design of tribology pairs, the Rayleigh step bearing is known as a bearing with the highest load capacity amongst all other possible bearing geometries. This paper mainly discusses a new high-speed bearing with shallow and deep cavities on the inner surface of the bearing, and further the physical phenomena in laminar flow and turbulence regimes was revealed. In doing so, the pressure distribution was calculated first using the continuity equations and then performances in the whole flow domain such as pressure distribution, load-carrying capacity, friction force and friction coefficient were calculated. In addition, a set of optimum geometries are shown to provide the highest load capacity for the Rayleigh step bearing under varied Reynolds number. Finally, associated conclusions were drawn by comparison between results under the coexistence state and under the laminar state.
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Yamane, Masami, Kyosuke Ono, and Kohei Iida. "Analysis of Tracking Characteristics and Optimum Design of Tri-Pad Slider to Micro-Waviness." Journal of Tribology 125, no. 1 (December 31, 2002): 152–61. http://dx.doi.org/10.1115/1.1510882.
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This paper describes optimum air-bearing design of a tri-pad slider in terms of tracking ability to micro-waviness based on theoretical analysis of the two-degree-of-freedom slider model and the distributed and concentrated air-bearing stiffness model. Although a short tri-pad type slider was introduced through the load/unload technique, we point out that this type of slider is superior to the traditional rail type slider in terms of tracking ability to micro-waviness. More importantly, the distance between head-gap position and the rear air-bearing center should be made as small as possible. The spacing variation due to lower mode resonance can be eliminated if the positions of front and rear air-bearing centers are located at the center of percussion. The resonance amplitude of the higher order mode in spacing variation can be reduced if the length of the rear air-bearing pad is designed to be 1.2∼1.3 times the wavelength of the higher mode resonance frequency. Since the momental stiffness of the front air-bearing prevents the head-gap from tracking micro-waviness, the front air-bearing length should be made short or the ratio of rear to front air-bearing stiffness should be made large. If the resonance amplitude of the lower mode must be decreased, the front air-bearing length should be designed to be 1.2∼1.3 times the wavelength of the lower mode resonance frequency.
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Zuo, Xiaobo, Shengyi Li, Ziqiang Yin, and Jianmin Wang. "Design and Parameter Study of a Self-Compensating Hydrostatic Rotary Bearing." International Journal of Rotating Machinery 2013 (2013): 1–10. http://dx.doi.org/10.1155/2013/638193.
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The influence of design parameters on the static performance of a newly designed self-compensating hydrostatic rotary bearing was investigated. The bearing was designed by incorporating the main attributes of angled-surface self-compensating bearing and opposed-pad self-compensating bearing. A governing model based on flow conservation was built to theoretically study the static performance, and the methodology was validated by experiments. It is pointed out that the influence factors on the bearing static performance are the designed resistance ratio of the restricting land to the bearing land, the inner resistance ratio of the land between pockets to that between the pocket and the drain groove, the initial clearance ratio of the restricting gap to the bearing gap, and the semiconical angle. Their effects on the load carrying capacity and stiffness were investigated by simulation. Results show that the optimum designed resistance ratio is 1; the initial clearance ratio should be small, and the inner resistance ratio should be large.
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Megson, T. H. G., and G. Hallak. "Optimum design of load-bearing box girder diaphragms having supports at the flange/web junctions." Thin-Walled Structures 22, no. 1 (January 1995): 39–49. http://dx.doi.org/10.1016/0263-8231(95)95936-u.
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Jafari, Mohammad, Seyed Ahmad Mahmodzade Hoseyni, Holm Altenbach, and Eduard-Marius Craciun. "Optimum Design of Infinite Perforated Orthotropic and Isotropic Plates." Mathematics 8, no. 4 (April 11, 2020): 569. http://dx.doi.org/10.3390/math8040569.
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In this study, an attempt was made to introduce the optimal values of effective parameters on the stress distribution around a circular/elliptical/quasi-square cutout in the perforated orthotropic plate under in-plane loadings. To achieve this goal, Lekhnitskii’s complex variable approach and Particle Swarm Optimization (PSO) method were used. This analytical method is based on using the complex variable method in the analysis of two-dimensional problems. The Tsai–Hill criterion and Stress Concentration Factor (SCF) are taken as objective functions and the fiber angle, bluntness, aspect ratio of cutout, the rotation angle of cutout, load angle, and material properties are considered as design variables. The results show that the PSO algorithm is able to predict the optimal value of each effective parameter. In addition, these parameters have significant effects on stress distribution around the cutouts and the load-bearing capacity of structures can be increased by appropriate selection of the effective design variables. The main innovation of this study is the use of PSO algorithm to determine the optimal design variables to increase the strength of the perforated plates. Finite element method (FEM) was employed to examine the results of the present analytical solution. The results obtained by the present solution are in accordance with numerical results.
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Lai, Tao, Xiaoqiang Peng, Junfeng Liu, Chaoliang Guan, Xiaogang Chen, Guipeng Tie, and Meng Guo. "Design optimization of high-precision aerostatic equipment based on orifice restriction." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 233, no. 10 (January 2, 2019): 3459–74. http://dx.doi.org/10.1177/0954406218819559.
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The aerostatic lubrication model with orifice restriction is built based on finite difference method. The model is solved by combination of flux-error feedback and optimization of grids parameter. The stiffness of aerostatic bearing can be improved by reducing the diameter of the orifice, but the optimum working gas gap is reduced and the processing difficulty of surface throttle is improved. The experiments of load and stiffness are carried out on the slider (50 × 50 mm) with the diameter of orifice at 50 µm. The experimental results and theoretical calculation are in good agreement; thus, the model is verified. The structural parameter of two, three, and four orifice gas-bearings is optimized, respectively, based on the proposed model, and the optimum positions of the orifices are obtained. According to the results, the aerostatic bearing guideways, made up of optical material (K9), are manufactured by some optical ways, and the lubrication of the small gas gap is guaranteed; meanwhile, the straightness accuracy of the aerostatic bearing guideways is 0.1 µm/200 mm. The analysis result verifies that the calculation method and the aerostatic lubrication model are significant to the design of high-precision aerostatic equipment.
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Wang, Zhanchao, Fei Guo, Ying Liu, Xiangfeng Liu, and Yuming Wang. "Design and fabrication of the tilting-pad thrust bearing surface profile." Industrial Lubrication and Tribology 70, no. 8 (November 12, 2018): 1402–7. http://dx.doi.org/10.1108/ilt-01-2018-0043.
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PurposeThis paper aims to design a new surface profile with simpler processing technology, which makes the bearing load carrying capacity (LCC) close to that of conventional tilting-pad thrust bearing.Design/methodology/approachThe paper analyzes the LCC of the thrust pad with crown profile and designs a new profile, whose performance is similar to the crown profile. The laser method is introduced to fabricate the new profile. The profile with tiny crown height can be fabricated by the laser with the proper parameters.FindingsIt was found that there is an optimum value, which is best in terms of the capacity of tilting-pad thrust bearing reach. The new profile with proper parameters can replace the crown profile.Originality/valueThe new profile can replace the crown profile and is easier to be made. The new design method could be adopted for designing the pad surface profile of the tilting-pad thrust bearing.
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Naidubabu, Y., G. Mohana Rao, K. Rajasekhar, and B. Ratna Sunil. "Design and simulation of polymethyl methacrylate-titanium composite bone fixing plates using finite element analysis: Optimizing the composition to minimize the stress shielding effect." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 231, no. 23 (September 8, 2016): 4402–12. http://dx.doi.org/10.1177/0954406216668550.
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Stress shielding is a mechanical phenomenon usually found in load-bearing bone implants. Difference in mechanical properties between the natural bone and the artificial implant leads to stress shielding problem. In the present work, polymethyl methacrylate and commercial pure titanium were selected to design laminate and particulate composites. Optimum composition was theoretically obtained that exhibits mechanical properties close to that of natural human bone. Bone fixing plate was designed for femur bone using computer-aided design. Finite element analysis was adopted to analyze the stress distribution in the bone and implant under static load conditions. Fixing plate with three screws was modeled and simulated using finite element analysis to investigate the stress distribution. Simulation was also done considering 316 L stainless steel as fixing implant and compared with the present optimized composition. Laminate composite with 0.3 volume fraction of titanium has shown mechanical properties close to the bone compared with other combinations. The results have clearly shown that the von-Mises stress induced in the bone with polymethyl methacrylate-titanium laminate composite plates was increased compared with the bone implanted with 316 L steel. Interestingly, laminate composites exhibited higher stresses in the bone compared with particulate composites. From the present design and simulation, it is clearly demonstrated that the laminate composites of polymethyl methacrylate–30% titanium can be an optimum choice for load-bearing implant materials with reduced stress shielding effect.
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Aydoğdu, İbrahim, Mukaddes Merve Kubar, Dahi Şen, Osman Tunca, and Serdar Çarbaş. "Optimum design of purlin systems used in steel roofs." Challenge Journal of Structural Mechanics 4, no. 3 (September 4, 2018): 89. http://dx.doi.org/10.20528/cjsmec.2018.03.002.
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In this study, one existing purlin system which is used in steel roof is optimized by taking into account less cost and bearing maximum load via developed software. This software runs with firefly algorithm which is one of the recent stochastic search techniques. One of the metaheuristic techniques, so-called firefly algorithm imitates behaviors of natural phenomena. Behaviors and communications of firefly are inspired by this algorithm. In optimization algorithm, steel sections, distance between purlins, tensional diagonal braces are determined as design variables. Design loads are taken into account by considering TS498-1997 (Turkish Code) in point of place where structure will be built, outside factors and used materials. Profile list in TS910 is used in selection stage of cross sections of profile. Constraints of optimization are identified in accordance with bending stress, deformation and shear stress in TS648. Design variables of optimization are selected as discrete variables so as to obtain applicable results. Developed software is tested on existing real sample so; it is evaluated with regard to design and performance of algorithm.
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Sharma, Sanjay, Gourav Jamwal, and Rajeev K. Awasthi. "Enhancement of steady state performance of hydrodynamic journal bearing using chevron-shaped surface texture." Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 233, no. 12 (May 2, 2019): 1833–43. http://dx.doi.org/10.1177/1350650119847369.
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In the present study, the optimum design parameters of chevron-shaped surface texture have been determined for the steady state performance enhancement of a hydrodynamic journal bearing. The fluid flow governing Reynolds equation has been solved using the finite element method, assuming iso-viscous and Newtonian fluid to obtain the static performance characteristics of textured hydrodynamic journal bearing. Different texture depths, areas and distributions have been numerically simulated and a set of optimum texture parameters has been determined based on the maximum performance enhancement ratio. The numerically obtained results indicate that surface texturing can improve bearing performance if the textured region is placed in the pressure build-up region. Moreover, surface texturing is the most effective at bearing performance enhancement when the bearing operates at lower eccentricity ratios. The performance enhancement ratio, which is the ratio of load-carrying capacity to coefficient of friction is found to be maximum at texture depth of 0.4, k = 0.3, textured zone located in the increasing pressure region and eccentricity ratio of 0.2.
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Cui, Li. "A new fatigue damage accumulation rating life model of ball bearings under vibration load." Industrial Lubrication and Tribology 72, no. 10 (June 1, 2020): 1205–15. http://dx.doi.org/10.1108/ilt-05-2019-0180.
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Purpose Bearings in electric machines often work in high speed, light load and vibration load conditions. The purpose of this paper is to find a new fatigue damage accumulation rating life model of ball bearings, which is expected for calculating fatigue life of ball bearings more accurately under vibration load, especially in high speed and light load conditions. Design/methodology/approach A new fatigue damage accumulation rating life model of ball bearings considering time-varying vibration load is proposed. Vibration equations of rotor-bearing system are constructed and solved by Runge–Kutta method. The modified rating life and modified reference rating life model under vibration load is also proposed. Contrast of the three fatigue life models and the influence of dynamic balance level, rotating speed, preload of ball bearings on bearing’s fatigue life are analyzed. Findings To calculate fatigue rating life of ball bearings more accurately under vibration load, especially in high speed and light load conditions, the fatigue damage accumulation rating life model should be considered. The optimum preload has an obvious influence on fatigue rating life. Originality/value This paper used analytical method and model that is helpful for design of steel ball bearing in high speed, light load and vibration load conditions. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-05-2019-0180/
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Shirazi, Mohammad Gharehzadeh, Ahmad Safuan Bin A. Rashid, Ramli Bin Nazir, Azrin Hani Binti Abdul Rashid, Hossein Moayedi, Suksun Horpibulsuk, and Wisanukhorn Samingthong. "Sustainable Soil Bearing Capacity Improvement Using Natural Limited Life Geotextile Reinforcement—A Review." Minerals 10, no. 5 (May 24, 2020): 479. http://dx.doi.org/10.3390/min10050479.
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Geotextiles are commercially made from synthetic fibres and have been used to enhance bearing capacity and to reduce the settlement of weak soil foundations. Several efforts have been made to investigate the possibility of using bio-based geotextiles for addressing environmental issues. This paper attempts to review previous studies on the bearing capacity improvement of soils reinforced with bio-based geotextiles under a vertical static load. The bearing capacity of the unreinforced foundation was used as a reference to illustrate the role of bio-based geotextiles in bearing capacity improvement. The effects of first geotextile depth to footing width ratio (d/B), geotextile spacing to footing width ratio (S/B), geotextile length to footing width ratio (L/B) and the number of reinforcement layers (N) on the bearing capacity were reviewed and presented in this paper. The optimum d/B ratio, which resulted in the maximum ultimate bearing capacity, was found to be in the range of 0.25–0.4. The optimum S/B ratio was in the range of 0.12–0.5. The most suitable L/B ratio, which resulted in better soil performance against vertical pressure, was about 3. Besides, the optimum number of layers providing the maximum bearing capacity was about three This article is useful as a guideline for a practical design and future research on the application of the natural geotextiles to improve the short-term bearing capacity of weak soil foundations in various sustainable geotechnical applications.
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Yuan, Ge Xia, Hong Zhao Liu, Yu Qiang Han, Ying Xiang Zhao, and Juan Ping Wang. "Optimum Design of a Kind of Split Type Compound Vessel Used in Ultrahigh Pressure Technology." Advanced Materials Research 148-149 (October 2010): 1458–63. http://dx.doi.org/10.4028/www.scientific.net/amr.148-149.1458.
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To enhance multilayer pressure vessels’ load bearing capacity, the paper presented a kind of split type compound vessel which employed split, shrink-fit and autofrettage techniques simultaneously. The vessel consists of a split layer made of sintered carbide, and an outer two-layer whole cylinder treated with autofrettage and shrink-fit. The mathematic model for the optimization design of the split type vessels was build based on stress analysis of each layer. In the model, the wall thickness of compound vessels is taken as an objective function; thickness of each layer, shrink-fit pressures, and the elastic-plastic radii of autofrettaged two layers are the design parameters; that Tresca stress of each layer equals to its design stress is constraint. An example was optimized. The results show that no additional strength was wasted in any of the layers at the optimum, and the vessels’ load capacity was far beyond the yield stress of outer whole cylinder.
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Fakoor, M., R. Rafiee, and M. Sheikhansari. "The influence of fiber-crack angle on the crack tip parameters in orthotropic materials." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 231, no. 3 (August 9, 2016): 418–31. http://dx.doi.org/10.1177/0954406215617195.
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Identification of the critical angle between fiber and crack direction in orthotropic materials for avoiding catastrophic failure is necessary. Recognition of the optimum regions for creating notches in orthotropic materials for creation of maximum load-bearing capability is an important parameter in structural design. In this paper, the critical angles between crack and fiber direction are predicted, extracting crack tip parameters in orthotropic materials using stress series expansion and numerical method. The variations of crack tip parameters with respect to the angle between crack and fiber for modes I and II are presented. The presented functions for these variations can be used in the optimum design procedure of orthotropic structures. The obtained results are validated using experimental study.
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Wang, Shou Yin, Jie Tang, and Hong Guang Li. "Topology Optimum Structural Design of the Pedestal in the Electro-Optical Theodolite." Applied Mechanics and Materials 365-366 (August 2013): 72–76. http://dx.doi.org/10.4028/www.scientific.net/amm.365-366.72.
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The pedestal of the theodolite is the main load-bearing part for the installation of the thrust bearings and torque motor stator, which is used to support the weight of the turntable and the pitching shaft system. So that the stiffness of it will have a direct impact on the ability of the theodolites capturing and tracking targets. In order to improve the overall theodolites tracking ability, to increase the stiffness of pedestal becomes more important. The 12 ribs were adopted topology optimization analysis by using the finite element software ANSYS. Through appropriately partitioning topology optimization elements and non-optimized elements, and setting optimization method, the structure of the model was optimized. The optimal ribs shape weve got under the condition of the largest stiffness pedestal structure, which reinforces the overall stiffness of the pedestal, and reduces the total weight.
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Megson, T. H. G., and G. Hallak. "Optimum design of load-bearing box girder diaphragms having supports at a distance from the flange/web junctions." Thin-Walled Structures 22, no. 4 (January 1995): 275–89. http://dx.doi.org/10.1016/0263-8231(94)00038-2.
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Hu, F., L. Q. Chen, B. Qi, and W. W. Chen. "Finit Element Analysis and Optimum Design of Time-Sharing 4WD Vehicle Main Reducer." Applied Mechanics and Materials 246-247 (December 2012): 692–96. http://dx.doi.org/10.4028/www.scientific.net/amm.246-247.692.
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By carrying on the stress and transform analysis of the box of a kind of main reducer which was self— designed and manufactured for vehicles, by ROMAX modeling get accurate bearing load and conducting ANSYS finite element analysis. it is shown that structure design of the main reducer box is very important for the intension capability of the box, and for the transmission functions of the main reducer. The hidden trouble of the main reducer transmission due to the designers was solved, which couldn’t estimate the transform of main reducer box by traditional design method, and provided the necessary basis for further optimizing and ameliorating the whole transfer case system. By using the UG software we constructed a complicated model of the box, and carried on a series of accurate intension and fatigued analyses for the model by using ANSYS software.
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Lee, Dong-Soo, and Dong-Hoon Choi. "Reduced Weight Design of a Flexible Rotor with Ball Bearing Stiffness Characteristics Varying with Rotational Speed and Load." Journal of Vibration and Acoustics 122, no. 3 (February 1, 2000): 203–8. http://dx.doi.org/10.1115/1.1303066.
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This paper presents an effective design approach for reducing the weight of a flexible rotor in ball bearings with rotational speed and load dependent stiffness characteristics under constraints on the system eigenvalues and bearing fatigue life. Design variables are chosen to be the inner radii of shaft elements, the positions of ball bearings, and the preloads on the bearings. The stiffness characteristics of high speed ball bearings are completely described as functions of applied loads and spin speed, and applied to the dynamic behavior analysis of a rotor-bearing system. A transfer matrix method is used to obtain eigenvalues of the system and an augmented Lagrange multiplier (ALM) method is employed as an optimization technique. A multi-stepped rotor supported by two angular contact ball bearings is analyzed and designed to show the speed and load dependent stiffness effect on the system dynamic behavior and to demonstrate the effectiveness of the proposed optimum design approach. The results show that the effect of the stiffness on the system dynamic behavior is noticeable and that the suggested design approach is effective. [S0739-3717(00)00803-5]
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Setyo Muntohar, Agus, Willis Diana, Edi Hartono, and Anita Widianti. "Improvement the california bearing ratio of expansive subgrade using SiCC column." MATEC Web of Conferences 195 (2018): 03003. http://dx.doi.org/10.1051/matecconf/201819503003.
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In Indonesia, many main roads have been constructed on problematic soil. The chemical improvement is widely used to shallow soil modification and stabilization. This paper introduces the use of a SiCC column to strengthen the load-bearing capacity of the expansive soil. In the road pavement design, California Bearing Ratio (CBR) is a most useful parameter to define the pavement layers. Hence, this paper is aimed to investigate the effect of SiCC column on the CBR of compacted expansive soil. Two groups of specimens were prepared for CBR test under soaked condition. A set of specimens are prepared on the wet side (Specimen A), and a set of specimens are compacted on the dry side of optimum moisture content (Specimen B). The objective of this research is to determine the effect of moisture content and dry density on the CBR value. The experiment results show that the SiCC column significantly increases the CBR of expansive soil on both dry and wet side of optimum moisture content. The specimen compacted on the dry side exhibit a higher CBR than the specimen compacted on the wet side of optimum moisture content.
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Ku, C. P. Roger, and Hooshang Heshmat. "Compliant Foil Bearing Structural Stiffness Analysis—Part II: Experimental Investigation." Journal of Tribology 115, no. 3 (July 1, 1993): 364–69. http://dx.doi.org/10.1115/1.2921644.
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This paper describes the second part of an investigation into the mechanism of deformation of the corrugated foil (bump foil) strips used in compliant surface foil bearings. In the earlier work, a theoretical model was developed to predict the structural characteristics of bump foil strips under various loads, including the effects of the friction forces between the compliant elements, local interaction forces, load distribution profiles, and bump configurations. In the experiments described here in, two-dimensional deflections of bump foils were recorded via an optical tracking system for a wide range of operating conditions to verify the feasibility of the theoretical model. Test results corroborate the theoretical model for the linear regions of load and the deflection parameters. The effects of the bearing design parameters, such as bump configuration, load profile, and surface coating and lubricant, on the structural characteristics of the bump foil strip were investigated. In addition, the source and mechanism of nonlinear behavior of the bump foil strips under light load conditions were examined, and more effective methods of achieving both Coulomb damping and optimum structural compliance were investigated. An understanding of the analytical and semi-empirical relations resulting from this work offers designers the potential for enhancing the design of high-performance compliant foil bearings.
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Varga, Rok, Bojan Žlender, and Primož Jelušič. "Multiparametric Analysis of a Gravity Retaining Wall." Applied Sciences 11, no. 13 (July 5, 2021): 6233. http://dx.doi.org/10.3390/app11136233.
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The design of a gravity retaining wall should be simple to construct, quick to build and the best economic solution to a problem. This can be achieved by using advanced optimization methods. Since geotechnical engineers are not always able to determine the exact soil properties and other project data, an optimal design of a gravity retaining wall should also be determined for a wide range of input parameters. Therefore, a multiparametric analysis of an optimal designed gravity retaining wall was carried out. Optimum designs of gravity retaining walls were obtained for 567 combinations of different design parameters. Diagrams were developed to help engineers determine the optimum section of the wall, based on construction costs. An exhaustive search was carried out within the available parameters (project data). The parameters were ranked according to which had the most influence on the optimum cost of the gravity retaining wall and the utilization of multiple constraints. The most important parameter for the optimal cost of a gravity retaining wall is the height of the retained ground, followed by the shear angle of the soil, the soil–wall interaction coefficient, the slope angle and the variable surcharge load. The shear angle of the soil is most relevant to the bearing capacity and eccentricity condition, while the soil–wall interaction coefficient is most relevant to the sliding condition. Since European countries apply different load, material and resistance safety factors, the optimization model was developed in a general form, where different design approaches and unit prices could be applied. The case study provides an improved optimization model for selecting the optimal design of gravity walls, for engineers.
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Kumar, Vivek, Satish C. Sharma, and Kuldeep Narwat. "Influence of micro-groove attributes on frictional power loss and load-carrying capacity of hybrid thrust bearing." Industrial Lubrication and Tribology 72, no. 5 (October 17, 2019): 589–98. http://dx.doi.org/10.1108/ilt-07-2019-0278.
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Purpose Micro-surface texturing is emerging as a possible way to enhance the tribological performance of hydrodynamic fluid film bearings. In view of this, numerical simulations are carried out to examine the influence of surface texture on performance of hybrid thrust bearing system. This paper aims to determine optimum attributes of micro-grooves for thrust bearing operating in hybrid mode. Design/methodology/approach An iterative source code based on finite element formulation of Reynolds equation has been developed to numerically simulate flow of lubricant through the bearing. Mass-conserving algorithm based on Jakobsson–Floberg–Olsson (JFO) condition has been used to numerically capture cavitation phenomenon in the bearing. Gauss Siedel method has been used to obtain steady state performance parameters of the bearings. Findings A parametric study has been performed to improve the load supporting capacity of the bearing by optimizing micro-groove attributes and configuration. It is noticed that use of full-section micro-groove is beneficial in improving the efficiency of bearing by enhancing the fluid film reaction and reducing the film frictional power losses. Originality/value This study is helpful in examining the usefulness of micro-groove textured surfaces in hybrid thrust bearing applications.
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Markin, Nerella, Schröfl, Guseynova, and Mechtcherine. "Material Design and Performance Evaluation of Foam Concrete for Digital Fabrication." Materials 12, no. 15 (July 30, 2019): 2433. http://dx.doi.org/10.3390/ma12152433.
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Three-dimensional (3D) printing with foam concrete, which is known for its distinct physical and mechanical properties, has not yet been purposefully investigated. The article at hand presents a methodological approach for the mixture design of 3D-printable foam concretes and a systematic investigation of the potential application of this type of material in digital construction. Three different foam concrete compositions with water-to-binder ratios between 0.33–0.36 and densities of 1100 to 1580 kg/m³ in the fresh state were produced with a prefoaming technique using a protein-based foaming agent. Based on the fresh-state tests, including 3D printing as such, an optimum composition was identified, and its compressive and flexural strengths were characterized. The printable foam concrete showed low thermal conductivity and relatively high compressive strengths of above 10 MPa; therefore, it fulfilled the requirements for building materials used for load-bearing wall elements in multi-story houses. Thus, it is suitable for 3D-printing applications, while fulfilling both load-carrying and insulating functions.
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Gunter, Edgar J., and Brian K. Weaver. "Kaybob Revisited: What We Have Learned about Compressor Stability from Self-Excited Whirling." Advances in Acoustics and Vibration 2016 (December 20, 2016): 1–17. http://dx.doi.org/10.1155/2016/7368787.
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The Kaybob compressor failure of 1971 was an excellent historic example of rotordynamic instability and the design factors that affect this phenomenon. In the case of Kaybob, the use of poorly designed bearings produced unstable whirling in both the low and high pressure compressors. This required over five months of vibration troubleshooting and redesign along with over 100 million modern U.S. dollars in total costs and lost revenue. In this paper, the history of the Kaybob compressor failure is discussed in detail including a discussion of the ineffective bearing designs that were considered. Modern bearing and rotordynamic analysis tools are then employed to study both designs that were considered along with new designs for the bearings that could have ultimately restored stability to the machine. These designs include four-pad, load-between-pad bearings and squeeze film dampers with a central groove. Simple relationships based on the physics of the system are also used to show how the bearings could be tuned to produce optimum bearing stiffness and damping of the rotor vibration, producing insights which can inform the designers as they perform more comprehensive analyses of these systems.
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Hiraki, S. "Optimum strength design of rear hub bearing for the light duty truck with dual tire — part 1: Measurement of actual bearing load with rear dual tire." JSAE Review 16, no. 3 (July 1995): 316. http://dx.doi.org/10.1016/0389-4304(95)95078-9.
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Belous, A. N., E. A. Dmitrenko, Ya Yu Goncharova, and O. E. Belous. "REDUCTION OF HEAT-MOISTURE IMPACT ON REINFORCED CONCRETE SILO FOR STORING CEMENT CLINKER." Vestnik Tomskogo gosudarstvennogo arkhitekturno-stroitel'nogo universiteta. JOURNAL of Construction and Architecture, no. 6 (December 29, 2019): 162–73. http://dx.doi.org/10.31675/1607-1859-2019-21-6-162-173.
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The paper analyzes various constructional options for insulation of load-bearing structures of reinforced concrete silo. Based on the analysis, the optimum insulation was selected according to the minimum temperature difference in the wall thickness. Factors affecting the heat-moisture characteristics of the walls of reinforced concrete silo are identified. The influence of heat-conducting inclusions on the heat-moisture characteristics of the building envelope is estimated. The temperature differences in the silo wall thickness are detected. The temperature and humidity are calculated for various design options and the moisture accumulation percentage of the con-struction is calculated for the specified time period.
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Walter, Fabian, and Michael Sinapius. "Influence of Aerodynamic Preloads and Clearance on the Dynamic Performance and Stability Characteristic of the Bump-Type Foil Air Bearing." Machines 9, no. 8 (August 23, 2021): 178. http://dx.doi.org/10.3390/machines9080178.
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The dry lubricated bump-type foil air bearing enables a carrying load capacity due to a pressure build up in a convergent air film. Since the air bearing provides low power dissipation above the lift-off speed and the flexible foil provides an adaptivity against high temperatures, manufacturing errors or rotor growth, the bump-type foil air bearing is in particular suitable for high speed rotating machineries. The corresponding dynamic behavior depends on the operational parameters, the behavior of the flexible foil structure, and in particular on the circumferential clearance. In order to avoid or suppress the critical subsynchronous motion at high rotational speeds, many researchers recommend adding an aerodynamic preload to the bore shape, representing a transition from a circular to a lobed bearing bore shape. In addition to positive effects on the stability, preliminary studies demonstrated degrading effects on the stiffness and damping due to increasing preload values. This observation leads to the assumption, that the preload value meets an optimum with respect to stability, load-capacity, and lift-off speed. With the aim of deriving an appropriate lobe configuration for the design of the bump-type foil air bearing, this work performs comprehensive numerical investigations on the dynamic performance and the stability characteristic as a function of preload and minimum clearance. To this end, this work uses steady-state and transient stability analysis methods to recommend optimal aeroydnamic preload values with respect to the corresponding minimum clearance.
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Ge, Jian Li, Guo Lai Yang, and Jian Wei Hao. "Modal and Transient Response Analysis for Complex Gear-Bearing System." Applied Mechanics and Materials 130-134 (October 2011): 1152–55. http://dx.doi.org/10.4028/www.scientific.net/amm.130-134.1152.
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The radar antenna pedestal is a complex gear-bearing system including three rotary motions, i.e. horizontal rolling, pitching rotation and azimuth rotation. In this paper, spring-dashpot elements and connection elements are applied to simulate gear meshing and bearing connection respectively. Moreover, the equivalent average stiffness and damping of teeth meshing and bearing connection are calculated. Then, quadrilateral shell elements, hexahedral elements, wedgy elements, connection elements and spring-dashpot elements are employed to build the finite element (FE) model of the gear-bearing system in Hypermesh software. Via intermediate file, the model is imported into ABAQUS software for modal analysis whose solutions agree well with experimental data. Then, impact acceleration is imposed on the three bolts of the underpan along the x-axis, y-axis and z-axis respectively. Dynamic stress distribution and regulation changing with time under impact load are obtained. From the numerical solutions, the regions where stress and deformation is lager are found. The method can provide significant reference to analysis and optimum design of the similar system.
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Naduvinamani, N. B., Siddharam Patil, and S. S. Siddapur. "On the study of Rayleigh step slider bearings lubricated with non-Newtonian Rabinowitsch fluid." Industrial Lubrication and Tribology 69, no. 5 (September 4, 2017): 666–72. http://dx.doi.org/10.1108/ilt-06-2016-0126.
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Purpose Nowadays, the use of Newtonian fluid as a lubricant is diminishing day by day, and the use of non-Newtonian fluids has gained importance. This paper presents an analysis of the static characteristics of Rayleigh step slider bearing lubricated with non-Newtonian Rabinowitsch fluid, which has not been studied so far. The purpose of this paper is to derive the modified Reynolds equation for Rabinowitsch fluids for two regions and to obtain the optimum bearing parameters for the Rayleigh step slider bearings. Design/methodology/approach The governing equations relevant to the problem under consideration are derived. The modified Reynolds equation is derived, and it is found to be highly non-linear and hence small perturbation method is adopted to find solution. Findings From this study it is found that there is an increase in the load-carrying capacity, pressure and frictional coefficients for dilatant fluids as compared to the corresponding Newtonian case. Further, for dilatant lubricants the maximum load-carrying capacity is attained for the slightly larger values of entry region length of Rayleigh step bearing as compared to Newtonian and pseudoplastic lubricants. Originality/value Rabinowitsch fluid is used for the study of lubrication characteristics of Rayleigh step bearings. The author believes that the paper presents these results for the first time.
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Lu, Chunping, Jianyu Li, and Dongli Tan. "Analysis on the Influence Mechanism of Cooling Water on Turbocharger and Optimum Coolant Mass Flow Rate Intelligent Prediction." Mathematical Problems in Engineering 2021 (January 27, 2021): 1–14. http://dx.doi.org/10.1155/2021/6674311.
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Due to the high speed and high temperature of engine exhaust, the turbocharger bears very high heat load. The heat dissipation of turbocharger is an important factor to determine the service life and performance of turbocharger. In this paper, a mathematical model of the fluid-structure interaction heat transfer of the water-cooled bearing body of turbocharger was established and the cooling performance of a 1.8 L gasoline engine turbocharger was analyzed. The effects of cooling water inlet flow, engine exhaust temperature, cooling water inlet temperature, and wall roughness of cooling water chamber on the cooling performance of important parts of the bearing body were analyzed by the numerical simulation method. In addition, the cooling water flow required by bearing body with a different structure under different working conditions was studied based on the orthogonal test method. The predicted result shows a good agreement with the experiment result, which could provide a reference for relevant production design and cooling strategy. In the range larger than the thickness of laminar flow bottom layer of the cooling water chamber wall, the increase of wall roughness height can enhance the heat transfer between the fluid and the solid.
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Haral, Ashwini. "An Experimental Study of Tribological Behavior of Journal Bearing Material under Powder and Granular Lubrication." International Journal for Research in Applied Science and Engineering Technology 9, no. 8 (August 31, 2021): 2553–57. http://dx.doi.org/10.22214/ijraset.2021.37811.
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Abstract: Proper lubrication of mechanical components is very important for the reliable efficiency and useful life. The working temperature of the components can affect the lubricating oil and can degrade the lubricating characteristics of oil. This paper presents the experimental investigation on tribological behaviour of journal bearing material. Two types of additives are used in lubricating oili.e., powder and granular types of additives. The investigation is carried out on pin-on-disc apparatus to determine the wear and coefficient of friction. The statistical analysis is performed using design of experiments and Taguchi robust design to determine the optimum parameters of lubricating additives. It is found that for constant speed of 400 rpm with 5% concentration with varying size the granular lubrication have lower values than powder lubrication for all load conditions Keywords: Lubrication, pin-on-disc, Taguchi, additives.
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Kumar, Rahul, Mohammad Sikandar Azam, Subrata Kumar Ghosh, and Hasim Khan. "Effect of surface roughness and deformation on Rayleigh step bearing under thin film lubrication." Industrial Lubrication and Tribology 69, no. 6 (November 13, 2017): 1016–32. http://dx.doi.org/10.1108/ilt-04-2017-0098.
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Purpose The aim of this paper is to study the effect of deterministic roughness and small elastic deformation of surface on flow rates, load capacity and coefficient of friction in Rayleigh step bearing under thin film lubrication. Design/methodology/approach Reynolds equation, pressure-density relationship, pressure-viscosity relationship and film thickness equation are discretized using finite difference method. Progressive mesh densification (PMD) method is applied to solve the related equations iteratively. Findings The nature and shape of roughness play a significant role in pressure generation. It has been observed that square roughness dominates the pressure generation for all values of minimum film thickness. Deformation more than 100 nm in bounding surfaces influences the film formation and pressure distribution greatly. Divergent shapes of film thickness in step zone causes a delay of pressure growth and reduces the load capacity with decreasing film thickness. The optimum value of film thickness ratio and step ratios have been found out for the maximum load capacity and minimum coefficient of friction, which are notably influenced by elastic deformation of the surface. Practical implications It is expected that these findings will help in analysing the performance parameters of a Rayleigh step bearing under thin film lubrication more accurately. It will also help the designers, researchers and manufacturers of bearings. Originality/value Most of the previous studies have been limited to sinusoidal roughness and thick film lubrication in Rayleigh step bearing. Effect of small surface deformation due to generated pressure in thin film lubrication is significant, as it influences the performance parameters of the bearing. Different wave forms such as triangular, sawtooth, sinusoidal and square formed during finishing operations behaves differently in pressure generation. The analysis of combined effect of roughness and small surface deformation has been performed under thin film lubrication for Rayleigh step bearing using PMD as improved methods for direct iterative approach.
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Zolina, Tatyana, and Pavel Sadchikov. "Optimization of Design Parameters for Materials Consumption for Reinforcing Metal Framework of Industrial Buildings." Applied Mechanics and Materials 875 (January 2018): 122–27. http://dx.doi.org/10.4028/www.scientific.net/amm.875.122.
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This study investigated optimum design methods for frame buildings with focus on minimization of economic costs. The methods discussed are intended to provide sufficient reserves for reliability of load-bearing steel structures. The analyzed mathematical models enable to assess seismic resistance of a structure and implement optimum design methods according to the selected key criterion. The available mathematical models assessing economic efficiency of metalwork reinforcement need further development. The model based on the principle of balanced risk is considered as the most appropriate for the study of structural reliability for industrial buildings. This model allows to assess the expected damage as compared with the initial spending on seismic protection. The focus is on setting and implementation of the task whose limiting condition provides equality between expenditures for reinforcement of damaged steel structures and those for damage prevention activities. Minimum of economic costs for construction or reconstruction of a structure is taken as the optimality criterion. This takes into account accumulation of damages within the standard life cycle and changes in stiffness of materials. Assessment of damage risk is based on the life cycle of a structure, its seismic resistance class and spending on damage repair. The study suggests a number of structural solutions that enable to reduce deformation of steel parts of the frame.
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Merin Jose, K., Divya Krishnan, and P. T. Ravichandran. "Behaviour of Vertically Loaded Piled Raft System." Journal of Computational and Theoretical Nanoscience 17, no. 5 (May 1, 2020): 2383–87. http://dx.doi.org/10.1166/jctn.2020.8900.
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A foundation gives the overall strength to a building by providing a level surface for the building to stand and distributing the total load uniformly to the underlying soil. The type of foundation to be chosen varies with the foundation soil and site conditions. Piled raft system are a type of foundation preferred when the bearing strata has less soil bearing capacity and a huge load has to be transferred. Thus Piled raft foundation is a foundation system which uses the combined effects of both rafts and piles such that it is expected to transfer huge loads without large settlement. An ample evaluation of factors like number of piles, length of piles, and degree of compaction of soil that affects the performance of the foundation is required, to understand the concept of piled raft foundation. This study was based on the behaviour of vertically loaded piled raft system by varying the length of pile as 100 mm, 150 mm and 200 mm with 4 and 9 numbers of pile conducted on loose and dense state in cohesion less soil. A vertical load test was conducted on unpiled raft both in loose and dense state of soil also and the results obtained from both piled and unpiled rafts were compared together. The compared results indicated an improvement in ultimate load capacity and settlement reduction. A settlement reduction of 32.71% and increased bearing capacity of 63.67% were observed when compared to unpiled raft under dense condition. About 84% of increase in bearing capacity of the piled raft system was observed with varying the degree of compaction of soil from loose to dense state of soil. An optimum design of this piled raft foundation can provide an alternative foundation for high rise buildings, transmission towers, bridges etc. and it can provide an aid to the threat of differential settlement for heavy loaded buildings in poor bearing strata.
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Saleh, Ahmed M., Wael Crosby, Ibrahim M. El Fahham, and M. Elhadary. "The effect of liner surface texture on journal bearing performance under thermo-hydrodynamic conditions." Industrial Lubrication and Tribology 72, no. 3 (February 10, 2020): 405–14. http://dx.doi.org/10.1108/ilt-06-2019-0239.
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Purpose The purpose of this paper is to study the effect of liner surface texture on journal bearing performance. Modeling the profile curvature of the dimples or grooves is planned for different cases of texture surface under thermo-hydrodynamic condition (THD). The aim of this paper is to determine the effect the texture surface on the performance of journal bearing and specify the optimum shape for texture dimples. Design/methodology/approach The paper was opted for an exploratory study by applying finite difference method to solve the energy equation, the heat conduction equations and the Reynolds equation numerically. The lubricant film thickness is divided to a mesh of 640,000 points. The equations were solved for each point of the mesh by using a MATLAB code. For texture shape optimization, 24 cases of different texture shapes were selected which includes elliptical, triangle and square curvature shape. Findings The paper provides theoretical insights about the effect of texture shape on journal bearing performance. It was concluded that to get a high load-carrying capacity, the direction of curvature is preferably to be perpendicular to the sliding direction. The convex texture has higher load carrying capacity than concave texture. Finally, the surface with textures in channel form yields better overall performance than the surface with several dimples. Originality/value This paper fulfils an identified need to study how texture surface affects the performance of journal bearing under thermo-hydrodynamic conditions.
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Adhikari, Navaraj, Nirajan Sharma Timilsina, Sanskar Gautam, Snehraj Kaphle, and Pratisthit Lal Shrestha. "Design and simulation of components of vacuum forming machine using household vacuum cleaner." Journal of Engineering Issues and Solutions 1, no. 1 (May 1, 2021): 138–57. http://dx.doi.org/10.3126/joeis.v1i1.36834.
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Plastic products ranging from toothbrushes to smartphones are an inseparable commodity in daily human life and their impact cannot be underestimated. This paper aims to design and simulate the vacuum forming process using readily available materials in context of Nepal. Vacuum forming process is a thermoforming process where the heated plastic sheet derives the shape of the mold through the application of vacuum and is used to make packaging products and other household products. Simulations were done to find out the optimum distance between the plastic sheet and the heater, arrangement of the wire in the heater, load bearing capacity of the design and the flow of vacuum in the arrangement. Nichrome wire coiled as heater coil is used as the heating material and laid in a spiral path with the plastic sheet 35mm below provided the best heating results and 1800W vacuum cleaner provided the necessary pressure of 85-90kPa and velocities of 100- 115m/s while the steel posts provided adequate strength.
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Yan, Qiang, Jianjun Zhang, and Kaicheng Qi. "Structure Design and Kinematics Analysis of a Novel Unpowered Load-Carrying Lower Extremity Exoskeleton with Parallel Topology." Mathematical Problems in Engineering 2018 (September 25, 2018): 1–10. http://dx.doi.org/10.1155/2018/4128520.
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A novel unpowered load-carrying parallel lower extremity exoskeleton is proposed. It is aimed at enhancing the load-bearing ability of the operator. Firstly, the structure of the novel exoskeleton is depicted in the second section; meanwhile, the degree of freedom concerning the exoskeleton is gotten by analyzing the number of links and the kinematic joints. Secondly, the forward position analysis of the exoskeleton for the swing leg is obtained. Using the expressions concerning the joints of knee and angle, the workspace of the swing leg in supporting gait circle is analyzed by the software of MATLAB. Thirdly, according to the schematic diagram of the mechanism, the static force analysis of the supporting leg for the exoskeleton is obtained. Finally, the static force of the supporting leg of the person who is not wearing the unpowered exoskeleton is gotten. Meanwhile, the genetic algorithm is used to get the optimum stiffness of the spring for energy-restoring device. By comparing the changes of force and torque for the supporting leg who is not wearing it and the skeleton which is worn by a person, some conclusions are carried out.
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Sukmak, Gampanart, Patimapon Sukmak, Suksun Horpibulsuk, Menglim Hoy, and Arul Arulrajah. "Load Bearing Capacity of Cohesive-Frictional Soils Reinforced with Full-Wraparound Geotextiles: Experimental and Numerical Investigation." Applied Sciences 11, no. 7 (March 26, 2021): 2973. http://dx.doi.org/10.3390/app11072973.
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This research investigated the effects of types of cohesive-frictional soil and geotextile reinforcement configurations on the bearing capacity of reinforced soil foundation (RSF) structures, via laboratory test and numerical simulation. The four reinforcement configurations studied for the RSF included: (i) horizontal planar form of geotextile, (ii) full-wraparound ends of geotextile, (iii) full-wraparound ends of geotextile with filled-in sand, and (iv) full-wraparound ends of geotextile with filled-in sand and sand backfill. The foundation soils studied were mixtures of fine sand and sodium bentonite at replacement ratios of 0, 20, 40, 60, 80, and 100% by dry weight of sand to have various values of plasticity index (PI). The numerical analysis of RSF structures was performed using PLAXIS 2D software. Several factors were studied, which included: embedment depth of the top reinforcement layer (U), width of horizontal planar form of the reinforcement (W), and spacing between geotextile reinforcement layers (H). Number of reinforcement layers (N) was varied to determine the optimum parameters of U/B, W/B, H/B, and N, where B is the footing width. The most effective improvement technique was found for the full wraparound ends of geotextile with filled-in sand and sand backfill. The outcome of this research will provide a preliminary guideline in a design of RSF structure with different ground soils and other RSF structures with different geosynthetic types.
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Jafari, M., and SA Mahmodzade Hoseyni. "Optimization of infinite orthotropic plates with hypotrochoid cutout under tensile loading using genetic algorithm." Journal of Reinforced Plastics and Composites 36, no. 5 (November 12, 2016): 360–76. http://dx.doi.org/10.1177/0731684416676634.
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The effect of geometric discontinuities can be reduced by appropriate choice of parameters affecting the stress distribution around cutout. This is possible if the effective parameters are accurately calculated. In this study, using genetic algorithm, the optimum parameters are introduced in order to achieve the minimum value of stress around cutout. Here, design variables are fiber angle, load angle, aspect ratio of cutout, shape of cutout, rotation angle of cutout, and bluntness parameters. Using the Lekhnitskii’s method, stress distribution around various cutouts is determined. The effect of the aforementioned parameters on the stress values around various shapes of cutouts such as quasi-triangular, quasi-square, and hypotrochoid cutouts is examined. Also, the optimal parameters for each cutout are introduced. The results showed that these parameters have significant effects on stress distribution around the cutouts and the structural load-bearing capacity will increase without changing the type of material if the parameters are correctly chosen.
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Kumar, Vivek, and Satish C. Sharma. "Magneto-hydrostatic lubrication of thrust bearings considering different configurations of recess." Industrial Lubrication and Tribology 71, no. 7 (September 9, 2019): 915–23. http://dx.doi.org/10.1108/ilt-10-2018-0370.
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Purpose This paper aims to numerically investigate the influence of magnetic field and recess configurations on performance of hydrostatic thrust bearing. Electrically conducting fluid is supplied to bearing, operating in external magnetic field. Influences of recess geometric shapes (circular, rectangular, elliptical and triangular) and restrictor (capillary and orifice) are numerically examined on stead-state and dynamic performance characteristics of bearing. Design/methodology/approach Numerical simulation of hydrostatic thrust bearing has been performed using finite element (FE) method based on Galerkin’s technique. An iterative source code based on FE approach, Gauss–Siedel and Newton–Raphson method is used to compute steady-state and dynamic performance indices of bearings. Findings The presence of magnetic field is observed to be enhancing load-carrying capacity and damping coefficient of bearings. The effect is observed to be more pronounced at low value of Hartmann number, because of the saturation effect observed at higher values of Hartmann number. The enhancement in abovementioned performance indices is observed to be highly dependent on geometry of recess and restrictor. Research limitations/implications This study presents a FE-based approach to numerically simulate a hydrostatic thrust bearing. It will help bearing designers and academician in selecting an appropriate recess shape, restrictor and strength of magnetic field, for obtaining optimum performance from hydrostatic thrust bearing. Originality/value The present investigation provides a coupled solution of modified Reynolds equation and restrictor equation, which is essential for accurately predicting the performance of hydrostatic thrust bearings.
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Zheng, Xi Jian, Jin Xia Ma, and Xiao Hua Chang. "Dynamic Simulation and Optimization of Suspension Rig Based on ADAMS." Applied Mechanics and Materials 365-366 (August 2013): 160–64. http://dx.doi.org/10.4028/www.scientific.net/amm.365-366.160.
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Take the large load temporarily installed suspended access equipment ZLP3000 by self-designed as the prototype, the rigid-flexible coupling dynamic model of suspension rig was established by using ADAMS based on the virtual prototyping technology. First, the reliability and accuracy of the model were verified by analysis of the model dynamics simulation. Second, the sensitivity analysis report of model design variables were generated by the establishment of the suspension rig parametric model. Finally, the parametric model was optimized based on the results of the sensitivity, the optimum scheme of suspension rig force bearing point and steel wire ropes lifting position were obtained, which could provide the basis for the rational use and layout of the steel wire ropes and steel.