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Dissertations / Theses on the topic 'Directional friction'
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1
Zhang, Cheng. "Robotic 3D friction stir welding : T-butt joint." Thesis, Högskolan Väst, Avd för automationssystem, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-8250.
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This Master Thesis was performed in terms of robotic three dimensional friction stir welding with T-butt joint. Friction stir welding (FSW) is a solid state welding method that achieves the weld temperature by friction of a rotating non-consumable tool with the workpiece. Science and technology fast developing requires for higher seam quality and more complex welding joint geometry like 3D welds. In order to acquire high productivity, capacity and flexibility with acceptable cost, robotic FSW solution have been proposed. Instead of the standard FSW machine, using a robot to perform complicated welds such as, three-dimensional. In this report, a solution for weld a 3D T-butt joint, which located in an aluminium cylinder with 1.5 mm thickness using a robot, was developed. Moreover, two new paths were investigated in order to avoid the use of two welds to perform this type of joint. The paths were tested on 2D and on 3D (with a 5050 curvature radius) geometries. Both paths had good results. What is more, the parameter developing methods of FSW process, which is composed of necessary parameter setting, positional compensation was introduced. Specially,the study demonstrates how complicate geometry can be welded using a robot. Also,it shows that TWT temperature control is able to acquire high quality 3D welds. In addition, an analysis of the 2D welding and 3D welding was performed, which exposed that, keeping exactly the same welding conditions, higher lateral forces on the tool were found during 3D welding. Basis on the special case in this paper, when the tool goes like "climbing" the sample, the suffering force of tool decreasing with increasing the height(Z position); nevertheless, when the tool goes like "downhill", the suffering force of tool decreasing with decreasing the height (Z position). What is more, in 2D weld, increasing the downforce (Fz) results increasing the lateral forces which can be Fx and/or Fy. Finally, the future works suggestions were presented in terms of (1) performing the new paths into a real cylinder, (2) performing tensile test on the paths and comparing it with conventional path which weld twice, (3) researching how the downforce (Fz) influence the Fx and Fy during welding of different 3D geometries, (4) how the cooling rate of backing bar influence the seam quality when it is use the same welding parameters and (5) the effect of performing welds in the same welding temperature achieved with different combination of the tool rotational speed and downforce on the material properties
2
Shields, Kelly J. "The Development of a Multi-Directional Wear Apparatus and the Characterization and Correlation of Biomechanical and Biotribological Properties of Bovine Articular Cartilage." VCU Scholars Compass, 2007. http://scholarscompass.vcu.edu/etd/1271.
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A multi-directional wear apparatus was developed to simulate the kinematic motion of diarthrodial joints. A comprehensive evaluation including biotribological and biomechanical characterization of articular surfaces was performed with concomitant translational and oscillating rotational motion similar to that experienced in vivo. Various system parameters were evaluated in the designed experiments including normal load magnitude (high/low), surface quality (defect/no defect), and wear pattern (with/without rotation). Biomechanical characterization was achieved through stress relaxation and dynamic cyclical testing. Quasi-linear viscoelastic theory was used to curve-fit the stress relaxation data, while the dynamic data was used to determine the dynamic properties through Fast Fourier Transform analysis and verify the assumptions posed with the QLV theory.Overall tissue compression was significantly dependent on load magnitude (pstatic was significantly dependent on surface quality (pinitial was significantly dependent on both surface quality (pComparisons of the curve-fit parameters showed a significant decrease in pre- vs post-wear elastic response, A, and viscous response, c. In addition, the short term relaxation response, τ1, showed a significant decrease between no defect (0.801 ± 0.13 sec) and a defect (0.679 ± 0.16 sec). lGlpost-wear/lGlpre-wear tan δ , was generally greater while lGl was less for those specimens experiencing rotation Qualitatively, SEM photographs revealed the mechanical degradation of the tissue surface due to wear. Surfaces with a defect had increased wear debris, which ultimately contributes to third body wear. Surfaces without a defect had preferentially aligned abrasions, while those surfaces outside the wear path showed no signs of wear.Significant correlation was detected between the μstatic and μinitial for both the nonliner viscous response, B (p2 (p<0.013 and p<0.062). Thus, the comprehensive evaluation of biomechanical and biotribological characteristics suggests the new wear regime and standardization of analysis techniques will aid in the development of functional articular repair and clinical repair techniques.
3
Barabanova, Liudmyla. "Frictional Anisotropy of Graphene and Graphene Based Materials." University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1461941753.
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Elwood, David E. Y. "Hydraulic fracture experiments in a frictional material and approximations for maximum allowable mud pressure." Thesis, Kingston, Ont. : [s.n.], 2008. http://hdl.handle.net/1974/1343.
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Koubek, Radek, and Karolina Dedicova. "Friction of wood on steel." Thesis, Linnéuniversitetet, Institutionen för byggteknik (BY), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-35094.
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This thesis deals with the experimental description of friction between steel and wood materials, specifically laminated veneer lumber (LVL) and pine wood with two types of annual rings. It studies the influence of a number of different parameters on the coefficient of friction such as contact pressure, moisture content, fiber orientation in relation to the load direction, steel surface roughness, and horizontal load rate. First, the theoretical mechanical and physical properties as well as the coefficient of friction itself are described. This is followed by the description of the test setup including the test method and how the obtained data is exported, handled and processed and how the coefficient of friction is determined. The results study the influence of different parameters and show that the coefficients of friction for the smooth sliding plate tests vary in between 0.1 and 0.3, whereas tests with the rough sliding plate vary around 0.7. Factors influencing the coefficient of friction were found to be the different moisture content under all tested pressures, the different fiber direction under low contact pressure, the contact pressure itself, though under higher pressures the influence was found to be low, and the horizontal load rate under low pressures. The outcomes are further discussed in the discussion chapter.
6
Yegneswaran, Kamalesh Madhavan Vis. "Deviation between the sliding direction of the chip over the tool and the direction of the friction force in oblique cutting /." Diss., Click here for available full-text of this thesis, 2006. http://library.wichita.edu/digitallibrary/etd/2006/t043.pdf.
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Thesis (M.S.)--Wichita State University, Dept. of Industrial and Manufacturing Engineering."July 2006." Title from PDF title page (viewed on October 30, 2006). Thesis adviser: Vis Madhavan. Includes bibliographic references (leaves 65-67).
7
Seo, Na Jin. "Biomechanical models of hand coupling for axial torque and push exertions effects of torque direction, hand-handle friction, and handle size on axial torque and push exertions for cylindrical handles." Saarbrücken VDM Verlag Dr. Müller, 2007. http://d-nb.info/991124189/04.
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Stránský, Jakub. "Optimalizace vybraných návrhových prvků ČSN pro projektování pozemních komunikací." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-227496.
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The master‘s thesis focuses on the optimization of the design values of curves of the horizontal alignments of the roads. It deals with the comparison of values between czech and foreign standards and differences between them. The practical part examines the values of the real speeds of vehicles passing through the curves of various parameters that were measured during measurements of selected curves during 2014. From these data a new design values are derived that could be used for the design of horizontal alignments.
9
Yang, Chen-tsung, and 楊振宗. "Simulation, Analysis and Applications of Direction-Optimized Friction Pendulum System." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/78686984471442649449.
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碩士逢甲大學
土木工程所
95
After many years of study, base isolation technology has been proven to efficiently reduce the seismic responses and upgrades the earthquake-proof capability of the superstructure either from the theoretical studies or the experimental efforts. Hence it has recently been used widely in the new or existing structures all around the world today. However, the base-isolated structures are easily to produce larger responses by strong ground motions with long predominant periods of near fault earthquakes due to and make structure resonance. In order to overcome the drawback, a new base isolator with variable isolation periods named as the Direction Optimized Friction Pendulum System (DO-FPS) has been proposed in this study. The proposed device is mainly composed of a spherical concave surface, a trench concave surface and an articulated slider. By using this special design, the isolation period will become dependent on the angle between the slider and the trench concave surface. Therefore, the undesirable phenomenon of resonance could always be prevented. In order to verify the functionality of the proposed device, a series of shaking table tests of a three story steel structure with DO-FPS base isolators were performed at the Department of Civil Engineering, Taichung, Feng Chia University, Taiwan. The test results revealed that the proposed device can effectively upgrade the seismic resistibility of a conventionally fixed base structure. Furthermore, the comparisons between the numerical and the experimental results show that the theory proposed in this study could predict the nonlinear behavior of the DO-FPS with good accuracy. Therefore, the proposed device can be considered as an excellent tool for upgrading the seismic resistibility of the traditional fixed base structure during severe earthquakes.
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Tsai, Wei-chan, and 蔡維展. "Applications of Multiple Direction Optimized-Friction Pendulum System to Structures." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/69078423127033878700.
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碩士逢甲大學
土木工程所
98
Multiple Direction Optimized Friction Pendulum System (MDO-FPS) is a kind of elastomeric-type base isolator. The friction coefficient, displacement capacity and radius of curvature of each sliding surface or intermediate sliding plate in each direction could be different. So the natural period and damping effect for a MDO-FPS isolator change continually during earthquakes. The MDO-FPS isolator also possesses an important characteristic in the natural period and damping effect that are a function of the directional angle of the sliding motion of the articulated slider during earthquakes. When contact is made with the displacement restrainer on the low-stiffness interface, the sliding motion on the low-stiffness interface will stop and the higher-stiffness interface continually sliding. It can effectively limit the displacement, avoid isolation system damage. In addition to it can limit the specific direction displacement which can be used to protect valuable equipment or facilities. Mathematical formulations of the MDO-FPS have been derived and using the “Multiple Yield and Bounding Surfaces Model” to show the hysteretic behavior of the MDO-FPS isolator in this article. In order to simulate the behavior of the MDO-FPS isolators that set on base of the structure. Using the computer program which call” NSAT (Nonlinear Stress Analysis Technique, develop byC.S.Tsai)”to do computer simulation test. Let people know how to design an ideal isolator. Furthermore, results from shaking table tests demonstrate that the proposed isolator provides good protection to structures for preventing damage from strong earthquakes.
11
Lin, Chung-Cheng, and 林中城. "Application of Direction Optimized - Friction Pendulum System to Motion Sensitive Equipment." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/82302344741196981526.
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-Lu, Chia, and 林家綠. "Simulation, Analysis and Applications of Multiple Direction Optimized- Friction Pendulum System." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/87094626899107636337.
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碩士逢甲大學
土木工程所
96
The earthquake is one kind of non-prewarning calamities happens suddenly , The consequence caused by an earthquake may be the most serious when compared to other disasters. After many years of study, base isolation technology has been proven to efficiently reduce the seismic responses and upgrades the seismic resistance capability of the superstructure either from theoretical studies or experimental efforts. Hence it has recently been used widely in the new or existing structures all around the world today. In order to avoid the possibility of resonance form the predominant period of the near-fault ground motion , a new base isolator with variable isolation periods named as the Multiple Direction Optimized-Friction Pendulum System (MDO-FPS) has been proposed in study. The proposed device is mainly composed of a spherical concave surface, a trench concave surface sliding plates and an articulated slider. The isolation period, displacement capacity and effect of the proposed isolator, with specially designed characteristic,is a function of the sliding angle and sliding diaplacement. A series of shaking table of a scaled three story steel structure isolated with the MDO-FPS base isolator were performed at the Department of Civil Engineering , Taichung , Feng Chia University, Taiwan. The experimental results reveal that the proposed device can effectively upgrade the seismic resistibility of a conventionally fixed base structure.
13
Chen, Ying-Shao, and 陳盈劭. "The Effects of Ellipticity and Motion Direction on Junction Growth and Friction Force." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/6jj7ch.
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碩士國立虎尾科技大學
機械與機電工程研究所
101
At this stage in the study of micro-mechanical components of the theoretical studies, however, are usually ignored the tangential speed, if we can have a better understanding of the characteristics of the micro-contact tangent interface can be found In fact, the tangential velocity of the micro-mechanical components the surface has a considerable impact, if there is a better understanding of the tangent interface, not only in the operation of the micro-mechanical components more effective solution to the operation of the machine, can be accurately control and achieve higher output value of more can effectively prolong the life of the micro-mechanical element. This research sonication cleaning the surface of the built recycling four proportion of pure copper specimen microcontact bench measurements and square quartz glass for analog two objects come into contact, the coefficient of friction and deformation arising the case of the interface increase. During the experiment to impose a positive load copper specimen with square quartz glass contact and then give all linear velocity is applied to the copper specimen in the the square quartz glass plane sliding, and to explore the two specimens in different contact angles angle, a different proportion of specimens of different load, the the copper specimen under different tangential velocity interface growth with the change of the deformation of the case, and in-depth understanding of the impact of the contact interface friction coefficient. The experimental results show that when copper specimen in contact with the quartz glass and generates a tangential sliding phenomenon, its interface growth with the amount of deformation are rendered the bigger the load increase and the greater the amount of deformation of the trend, but growth and deformation situation are concentrated in the initial stage, the contact angle and ellipticity little effect on growth and deformation situation. So the interface growth in the amount of deformation is proportional to the forward load. To the predefined parameters (load 50N, 100N, 170N speed 10 m / s, 20 m / s, 30 m / s), the coefficient of friction experimental results are presented the case of the smaller the load the greater the friction coefficient, tangential slip velocity ellipse ratio and contact angle has little effect on the friction coefficient.
14
Tseng, Ya-Fang, and 曾雅芳. "Experimental Study of Light Weight Equipment Isolated with Multiple Direction Optimized-Friction Pendulum System." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/07510417032010415750.
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碩士逢甲大學
土木工程所
99
Proposed in this study is a Multiple Directional Optimized-Friction Pendulum System (MDO-FPS) which uses various friction coefficients, radii of curvature and displacement capacities on sliding interfaces to achieve self-adjusting the natural period, damping effect and displacement capacity of the base isolator. Therefore, it is not easy to resonate with the vibrations of the ground motions and can effectively provide good protection to equipment housed in a building by reducing its responses under near fault and severe earthquakes. In addition, an equivalent system, based on the series theory, has been derived to model the mechanical characteristic of the MDO-FPS isolator by using available commercial computer programs such as Etabs and Sap2000 software. Furthermore, in order to investigate the effectiveness of the MDO-FPS isolator on seismic mitigation, a series of shaking tables of isolated equipment was carried out in the National Center for Research on Earthquake Engineering, Taipei, Taiwan. Results from the uni-, bi- and tri-directional ground shaking tests reveal that the structural responses have been reduced significantly by more than 60%.
15
Yegneswaran, Kamalesh. "Deviation between the sliding direction of the chip over the tool and the direction of the friction force in oblique cutting." Thesis, 2006. http://hdl.handle.net/10057/360.
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Pure oblique cutting experiments with conventional cutting tools as well as ultra-sharp tools have been carried out under a wide range of cutting conditions using a linear slide based cutting set-up. The chip flow direction was measured using the 3D Digital Image Correlation (DIC) technique of high-speed stereoscopic images and the frictional force direction was determined from forces. It is estimated that the error in chip flow angle measurements using DIC, was approximately ±1°, as was the error in friction force direction measurements from forces. An increasing trend of the angles with an increase in feed and a decreasing trend of the angles with an increase in speeds were observed. It was found that under many conditions, there is a significant difference between the chip flow direction and the friction force direction. This difference decreases with increase in friction co-efficient and with increasing sharpness of the cutting edge. However, with ultra-sharp microtome knives there is a small but finite difference between the chip flow direction and the friction force direction. By the use of DIC to measure the chip flow angle at different points along the back of the chip, it is found that there was no variation in chip-flow angle over the width of the chip.Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Industrial and Manufacturing Engineering
Includes bibliographic references (leaves 65-67)