Academic literature on the topic 'Linear Displacement Profile (LDP)'
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Journal articles on the topic "Linear Displacement Profile (LDP)"
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Malena, Marialaura, and Gianmarco de Felice. "Analytical Modeling of Composite-to-Masonry Prisms Bond." Key Engineering Materials 624 (September 2014): 567–74. http://dx.doi.org/10.4028/www.scientific.net/kem.624.567.
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The composite-to-substrate interfacial stresses transfer mechanism is one of the critical issues in externally-bonded structural strengthening by means of composite fabrics. In this work, an analytical approach for modeling the debonding process of a composite on a non-homogeneous substrate is developed and applied to simulate the loss of bond of FRP on brick masonry. The analytical formulation is based on the experimental outcomes of bond shear tests, which are part of a Round Robin activity involving several laboratories. The experimental work is the follow up of a previous one [1], and comprises 12 single-lap shear tests of four kinds of unidirectional reinforcement, i.e., glass, carbon, basalt and steel, applied with epoxy resin to masonry prisms composed by five clay bricks and four mortar joints. The analytical simulations of the experimental tests rely upon a bi-linear non-homogeneous bond-slip law that was calibrated using the experimental population. Eventually, the analytical results are compared to experimental ones both, in terms of global (load to displacement curve) and local behavior (strain profile on the reinforcement for increasing load values).
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Irubetagoyena, I., M. Verset, S. Palierne, P. Swider, and A. Autefage. "Ex vivo cyclic mechanical behaviour of 2.4 mm locking plates compared with 2.4 mm limited contact plates in a cadaveric diaphyseal gap model." Veterinary and Comparative Orthopaedics and Traumatology 26, no. 06 (2013): 479–88. http://dx.doi.org/10.3415/vcot-13-07-0089.
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SummaryObjectives: To compare the mechanical properties of locking compression plate (LCP) and limited contact dynamic compression plate (LC-DCP) constructs in an experimental model of comminuted fracture of the canine femur during eccentric cyclic loading.Methods: A 20 mm mid-diaphyseal gap was created in eighteen canine femora. A 10-hole, 2.4 mm stainless steel plate (LCP or LC-DCP) was applied with three bicortical screws in each bone fragment. Eccentric cyclic loadings were applied at 10 Hertz for 610,000 cycles. Quasistatic loading / unloading cycles were applied at 0 and 10,000 cycles, and then every 50,000 cycles. Structural stiffness was calculated as the slope of the linear portion of the load-displacement curves during quasistatic loading / unloading cycles.Results: No bone failure or screw loosening occurred. Two of the nine LCP constructs failed by plate breakage during fatigue testing, whereas no gross failure occurred with the LC-DCP constructs. The mean first stiffness of the LCP constructs over the course of testing was 24.0% lower than that of constructs stabilized by LC-DCP. Construct stiffness increased in some specimens during testing, presumably due to changes in boneplate contact. The first stiffness of LC-DCP constructs decreased by 19.4% and that of locked constructs by 34.3% during the cycling period. A biphasic stiffness profile was observed: the second stiffness was significantly greater than the first stiffness in both groups, which allowed progressive stabilization at elevated load levels.Clinical significance: Because LCP are not compressed to the bone, they may have a longer working length across a fracture, and thus be less stiff. However, this may cause them to be more susceptible to fatigue failure if healing is delayed.
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Singh, Rahul Kumar, Sun Woh Lye, and Jianmin Miao. "PVDF Nanofiber Sensor for Vibration Measurement in a String." Sensors 19, no. 17 (August 29, 2019): 3739. http://dx.doi.org/10.3390/s19173739.
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Flexible, self-powered and miniaturized sensors are extensively used in the areas of sports, soft robotics, health care and communication devices. Measurement of vibration is important for determining the mechanical properties of a structure, specifically the string tension in strings. In this work, a flexible, lightweight and self-powered sensor is developed and attached to a string to measure vibrations characteristics in strings. Electrospun poly(vinylidene) fluoride (PVDF) nanofibers are deposited on a flexible liquid crystal polymer (LCP) substrate for the development of the sensor. The electrospinning process is optimized for different needle sizes (0.34–0.84 mm) and flow rates (0.6–3 mL/h). The characterization of the sensor is done in a cantilever configuration and the test results indicate the sensor’s capability to measure the frequency and strain in the required range. The comparison of the results from the developed PVDF sensor and a commercial Laser Displacement Sensor (LDS) showed good resemblance (±0.2%) and a linear voltage profile (0.2 mV/με). The sensor, upon attachment to a racket string, is able to measure single impacts and sinusoidal vibrations. The repeatability of the results on the measurement of vibrations produced by an impact hammer and a mini shaker demonstrate an exciting new application for piezoelectric sensors.
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Wang, Yonghong, Wen Du, Guohui Zhang, and Yang Song. "The Longitudinal Deformation Profile of a Rock Tunnel: An Elastic Analysis." Mathematical Problems in Engineering 2021 (April 2, 2021): 1–12. http://dx.doi.org/10.1155/2021/6684035.
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The longitudinal deformation profile (LDP) is the profile of wall displacement versus the distance from the tunnel face. To develop LDP equations, numerical methods and in situ experiments have been used to obtain the deformation of a tunnel in three-dimensional space. However, extant approaches are inadequate in terms of explaining the mechanical relation between the wall displacement and the conditions of a tunnel (e.g., properties of rock). In this paper, an analytical approach is proposed to develop a new LDP equation. First, on the basis of the axisymmetric elastic model of a tunnel, a closed-form solution of wall displacement is derived. Then, a new LDP equation is presented according to the solution developed above; the coefficient β, defined as the ratio of the effective range of the “face effect” to the radius of the tunnel, is proposed for the first time. Finally, a case study is proposed to validate the practicability of this equation.
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Ha, Sang-gui, Abdul Muntaqim Naji, Hafeezur Rehaman, Kyoung-min Nam, Han-eol Kim, Jae-won Park, and Han-kyu Yoo. "Expanded Longitudinal Deformation Profile in Tunnel Excavations Considering Rock Mass Conditions via 3D Numerical Analyses." Applied Sciences 11, no. 12 (June 10, 2021): 5405. http://dx.doi.org/10.3390/app11125405.
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In the convergence–confinement method, the longitudinal deformation profile (LDP) serves as a graphical representation of the actual tunnel convergence (both ahead of and behind the face); therefore, it is considered important for determining the distance of support installation from the face or the timing after excavation in this method. The LDP is a function of the rock mass quality, excavation size, and state of in situ stresses; thus, obtaining the LDP according to the rock mass conditions is essential for analyzing the complete behavior of convergence during tunnel excavation. The famous LDP shows that the best fit for the measured values of tunnel internal displacement reported simply expresses the ratio of the preceding displacement as approximately 0.3. This can lead to an error when predicting the ratio of the preceding displacement while neglecting the rock conditions; consequently, a complete tunnel behavior analysis cannot be realized. To avoid such error, the finite difference method software FLAC 3D is used to develop an expanded longitudinal deformation profile (ELDP) according to the rock mass conditions. The ELDP is represented by graphs featuring different shapes according to the rock mass rating (RMR), and the empirical formula of the LDP best fitted for the tunnel convergence measurement values is expanded. This expanded LDP formula is proposed in a generalized form, including the parameters α and β from the empirical equation. These parameters α and β are expressed as functions of the RMR and initial stress. Statistical analysis results of the 3D numerical analysis of 35 cases were analyzed in the ranges of α = 0.898–2.416 and β = 1.361–2.851; this result is based on the empirical formula of Hoek (1999) (α = 1.1, β = 1.7), which was expanded in the current study according to the rock quality and initial stress conditions.
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Furutani, Ryoshu. "UNCERTAINTY ESTIMATION OF CONSTRUCTED METROLOGY FRAME." International Journal "Advanced Quality" 45, no. 2 (June 22, 2017): 37. http://dx.doi.org/10.25137/ijaq.n2.v45.y2017.p37-42.
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In general, the profile measuring machine uses the displacement sensor attached on movable mechanism in order to measure the object. It could measure the object profile by the amount of movement of the displacement sensor and output of the displacement sensor. When measuring the object, metrological frame is important as a reference. If the metrological frame has some profile errors, the output of the displacement sensor includes the profile error of the metrological frame. We proposed a new method to distinguish the profile error of the metrological frame from the output of the displacement sensor. This method requires two linear stages and a displacement sensor. The object profile and profile error of the movable mechanism are determined by calculation using output of the displacement sensor. The validity of the new method was confirmed by the simulation andexperiment. It was confirmed to be possible to construct metrological frame below 1μm. As a lot of number of iteration are required, the reduction of iteration was discussed. As a result of reduction of measurement, the uncertainties of measurement are shown and compared.
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Goh, Ker Liang. "Displacement-Time Graph of a Point on a Wave Pulse." Physics Educator 03, no. 03 (September 2021): 2120001. http://dx.doi.org/10.1142/s2661339521200018.
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G. Yakubu, G. Sani, S. B. Abdulkadir, A. A.Jimoh, and M. Francis. "FULL CAR ACTIVE DAMPING SYSTEM FOR VIBRATION CONTROL." International Journal of Engineering Technologies and Management Research 6, no. 4 (March 25, 2020): 1–17. http://dx.doi.org/10.29121/ijetmr.v6.i4.2019.365.
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Full car passive and active damping system mathematical model was developed. Computer simulation using MATLAB was performed and analyzed. Two different road profile were used to check the performance of the passive and active damping using Linear Quadratic Regulator controller (LQR)Road profile 1 has three bumps with amplitude of 0.05m, 0.025 m and 0.05 m. Road profile 2 has a bump with amplitude of 0.05 m and a hole of -0.025 m. For all the road profiles, there were 100% amplitude reduction in Wheel displacement, Wheel deflection, Suspension travel and body displacement, and 97.5% amplitude reduction in body acceleration for active damping with LQR controller as compared to the road profile and 54.0% amplitude reduction in body acceleration as compared to the passive damping system. For the two road profiles, the settling time for all the observed parameters was less than two (2) seconds. The present work gave faster settling time for mass displacement, body acceleration and wheel displacement.
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Arai, Yoshikazu, Atsushi Shibuya, Y. Yoshikawa, and Wei Gao. "Online Measurement of Micro-Aspheric Surface Profile with Compensation of Scanning Error." Key Engineering Materials 381-382 (June 2008): 175–78. http://dx.doi.org/10.4028/www.scientific.net/kem.381-382.175.
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A novel scanning probe measurement system has been developed to achieve precise profile measurements of micro-aspheric surfaces. The system consists of a scanning stage (a spindle and a linear slide) and a sensor unit. The sensor unit consists of a ring artifact, two capacitance sensors and a contact-mode displacement sensor. The two capacitance sensors scan the surface of the ring artifact to measure and compensate the error motions of the scanning stage while the contact-mode displacement sensor scans the surface of a micro-aspheric. In this paper, a new contact-mode displacement sensor that has a small contact force of less than 2.3 mN and a stable output has been developed. After investigating the fundamental performance of the contact-mode displacement sensor, the sensor has been applied to the micro-aspheric surface profile measurement system. The effectiveness of the measurement system has been verified by the measurement results.
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Chen, Hong Niao, Jia Jian Chen, and Ray Kai Leung Su. "Detection of Crack Evolution in Plain Concrete by Electronic Speckle Pattern Interferometry." Key Engineering Materials 744 (July 2017): 92–96. http://dx.doi.org/10.4028/www.scientific.net/kem.744.92.
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In order to study crack evolution in concrete, Electronic Speckle Pattern Interferometry (ESPI) technique was applied to measure full-field displacement of concrete beam subjected to three-point bending. Basic principles of ESPI technique were introduced. Mid-span deflection and crack mouth opening displacement were measured by linear variable differential transformers (LVDTs) and clip gauge, respectively. Typical load-displacement curves measured by different methods were compared and analyzed. Analysis results indicated that ESPI results were in good agreement with that measured by LVDT (clip gauge), verifying the validity and accuracy of ESPI measurement. From displacement contours, crack evolution including its initiation and propagation was observed. Furthermore, strain profiles near the crack at different loading levels were determined. Strain profile was nearly linear before crack initiation and became nonlinear with crack growth.
Dissertations / Theses on the topic "Linear Displacement Profile (LDP)"
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VLACHOPOULOS, NICHOLAS. "Back Analysis of a Tunnelling Case Study in Weak Rock of the Alpine System in Northern Greece: Validation and Optimization of Design Analysis Based on Ground Characterization and Numerical Simulation." Thesis, 2009. http://hdl.handle.net/1974/5116.
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The backdrop for this research paper is the tunnelling that is currently nearing completion in the Epirus region of Northern Greece, as part of the Egnatia Odos Highway construction. Highly deformed and altered sediments and low grade rock masses dominate the near surface environment creating a variety of technical challenges for tunnelling. Accurate equivalent rock
mass performance reductions for tunnels in these materials is complicated by geomorphologic peculiarities such as those found in Flysch materials. The mechanisms of rock-support interaction related to face or near-face reinforcement systems are poorly understood at this time. As well, the
mechanics of weak rock materials in the complex deformation regime in advance of a tunnel face are not robustly integrated into current 2D design models. Design decisions are currently possible using empirical techniques and simplified models, but a true optimized and mechanicsbased design process for the various support technologies are not fully developed. This research addresses elements of such issues, such as: use of the Longitudinal Displacement Profile (LDP)
of the Convergence-Confinement method of tunnel design, relating 2D numerical models to their distance from the face using the size of the plastic zone as an indicator, near face tunnel support analysis in weak rock masses, boundary condition assessment for numerical modelling of such weak rock masses, the influence of plasticity zones surrounding tunnel excavations, and
modelling optimization techniques for weak rock tunnelling in order to optimize the design of such underground structures and better predict near-face deformation and yield development. This work involved the use of 2D and 3D numerical models of tunnel sequencing for numerical simulation of composite material behaviour and sequential tunnel deformation response.Thesis (Ph.D, Geological Sciences & Geological Engineering) -- Queen's University, 2009-09-01 08:46:30.537
Conference papers on the topic "Linear Displacement Profile (LDP)"
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Im, Ju Hyun, Ju Hyun Shin, Garth V. Hobson, Seung Jin Song, and Knox T. Millsaps. "Effect of Leading Edge Roughness and Reynolds Number on Compressor Profile Loss." In ASME Turbo Expo 2013: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/gt2013-95487.
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An experimental investigation has been conducted to characterize the influence of leading edge roughness and Reynolds number on compressor cascade profile loss. Tests have been conducted in a low-speed linear compressor cascade at Reynolds numbers between 210,000 and 640,000. Blade loading and loss have been measured with pressure taps and pneumatic probes. In addition, a two-component laser-doppler velocimeter (LDV) has been used to measure the boundary layer velocity profiles and turbulence levels at various chordwise locations near the blade suction surface. The “smooth” blade has a centerline-averaged roughness (Ra) of 0.62 μm. The “rough” blade is roughened by covering the leading edge of the “smooth” blade, including 2% of the pressure side and 2% of the suction side, with a 100 μm-thick tape with a roughness Ra of 4.97 μm. At Reynolds numbers ranging from 210,000 to 380,000, the leading edge roughness decreases loss slightly. At Reynolds number of 210,000, the leading edge roughness reduces the size of the suction side laminar separation bubble and turbulence level in the turbulent boundary layer after reattachment. Thus, the leading edge roughness reduces displacement and momentum thicknesses as well as profile loss at Reynolds number of 210,000. However, the same leading edge roughness increases loss significantly for Re = 450,000 ∼ 640,000. At Reynolds number of 640,000, the leading edge roughness decreases the magnitude of the favorable pressure gradient for axial chordwise locations less than 0.41 and induces turbulent separation for axial chordwise locations greater than 0.63, drastically increasing loss. Thus, roughness limited to the leading edge still has a profound effect on the compressor flow field.
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Cole, Gregory A., and James D. Van de Ven. "Design of a Variable Radius Piston Profile Generating Algorithm." In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-11364.
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One of the main sources of efficiency loss in heat engines is the inability of a sinusoidally displaced piston engines to approximate the ideal heat volumetric cycles the engines require. While attempts have been made to address this issue in the past, recent developments in Stirling engine technology utilizing rolling diaphragm seals on the cylinders has offered an opportunity to greatly increase the correlation between an engines volume-time profile to the ideal profile. By changing the radius of the piston used to drive the rolling diaphragm connection over its length, the piston can effectively be used as a “transfer function” translating the sinusoidal displacement of the crankshaft into a near ideal heat cycle volumetric displacement. This work presents a methodology for determining the ideal shape of such a piston, and a model used to most effectively match a desired input linear displacement profile with output volumetric displacement profile, without compromising the operating conditions required to maintain the diaphragm itself.
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Katsenis, Loukas C., Constantine A. Stamatopoulos, and Vassilis P. Panoskaltsis. "EMPIRICAL EXPRESSION PREDICTING SEISMIC DISPLACEMENT OF SANDY SLOPES IN GREECE IN TERMS OF SOIL PROFILE TYPE USING NON-LINEAR DYNAMIC STICK-SLIP ANALYSIS." In XI International Conference on Structural Dynamics. Athens: EASD, 2020. http://dx.doi.org/10.47964/1120.9030.20195.
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Nava, Vincenzo, Felice Arena, and Alessandra Romolo. "Non-Linear Random Wave Groups With a Superimposed Current." In 25th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2006. http://dx.doi.org/10.1115/omae2006-92477.
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In this paper a new solution for non-linear random wave groups in the presence of a uniform current is obtained, by extending to the second-order the Boccotti’s ‘Quasi-Determinism’ (QD) theory. The second formulation of the QD theory gives the mechanics of linear random wave groups when a large crest-to-trough wave height occurs. Here the linear QD theory is firstly applied to the wave-current interaction. Therefore the nonlinear expressions both of free surface displacement and velocity potential are obtained, to the second-order in a Stokes’ expansion. Finally some numerical applications are presented in order to analyze both the wave profile and the wave kinematics.
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Sundaresan, S., K. Ishii, and D. R. Houser. "A Procedure Using Manufacturing Variance to Design Gears With Minimum Transmission Error." In ASME 1989 Design Technical Conferences. American Society of Mechanical Engineers, 1989. http://dx.doi.org/10.1115/detc1989-0084.
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Abstract This paper deals with the design of spur gears that have minimum transmission error and are insensitive to manufacturing variance. We address two stages of design: 1) generation of candidate designs (selection of number of teeth, pressure angle, etc.), and 2) tooth profile modification. The first stage involves a search of discrete combinations of design variables, while the second stage utilizes numerical optimization techniques. The key research issue is finding a candidate design and its profile modification that not only has low transmission error, but is insensitive to variations in the design values caused by the manufacturing process. To achieve this goal, the procedure applies Taguchi’s concept of parameter design. In this paper, we consider a design problem with a set specification: fixed center distance, speed ratio, and transmission torque. We seek to find a limited number of candidate designs by applying conventional design generation techniques and some design heuristics. For each candidate design, the procedure determines the optimum profile modification (linear tip relief) by linking the Load Distribution Program (LDP) for gears with an optimization program package (OPTPAK). From the resulting peak optimum, we further seek the statistical optimum using an algorithm developed in this paper. The statistical optimum shows a nominal increase in the transmission error, but is quite insensitive to typical process error associated with gear manufacturing. The developed algorithm readily applies to other gear designs as well as other types of machine elements. In particular, we foresee our procedure to be particularly effective for helical gears. We hope to further our method by developing a means to add statistical heuristics to the discrete design generation stage.
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Kumanchik, Lee, Tony Schmitz, Jon Pratt, and John Ziegert. "Full Field Displacement Measurements of AFM Cantilevers During Loading." In ASME 2007 International Manufacturing Science and Engineering Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/msec2007-31041.
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Research collaboration between the University of Florida and National Institute of Standards and Technology is focused on the development of a reference standard for atomic force microscope (AFM) cantilever stiffness calibration. The end goal is production of flexure-based artifacts that exhibit low fabrication expense, stiffness adjustability by design, insensitivity to load application point, mechanical robustness, and good reproducibility. Experimental determination of AFM cantilever spring constants is important because the measured forces are inferred from the cantilever displacement and a linear relationship between force and displacement. As a first step in this study, we have constructed a test setup that enables us to: 1) monitor AFM cantilever behavior during loading; and 2) record the shape of the cantilever under test during contact to better understand boundary conditions. The fundamental metrology tool employed by the test setup is a three-dimensional optical profiler, or scanning white light interferometer. By locating the cantilever (and test surface) within the measurement area of the profiler, we are able to record “snapshots” of the cantilever shape under various loading conditions. Given the deflected shape, we can make comparisons between the actual shape and the profile that would be obtained by ideal (fixed-free) boundary conditions. Results for cantilevers with various stiffness values (spanning four orders of magnitude) are presented and comparisons with ideal deflected shapes are provided.
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Fung, Eric H. K., W. O. Wong, and M. Zhu. "An On-Machine Separation Method for Straightness, Yawing and Rolling Errors of a Linear Slide." In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-10438.
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A novel method based on Fourier series for the measurement of motion, yawing and rolling error is proposed in this study. In this method, a stationary stage with eight sensors, three of which are laid in the upper row and the rest are positioned in the lower row, is used as the data acquisition device. While the carriage of a lathe is sliding on the bed in one direction, the sensors capture the displacement data from the facing machine profile. Based on the existing “F5S” method, a new method is proposed to obtain the three major time-varying error components, which are the on-machine motion error, the yawing error and the rolling error, together with the shape functions of the machine profile. Mathematical proof and working principle are included in the paper. Verification of the method applicability is carried out by computer simulation. To evaluate the results of the method, the input data and calculated data are compared. It is shown that the new method is capable to separate all input error components with acceptable accuracy.
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Mori, Taichi, Yoshitaka Morimoto, Akio Hayashi, Yoshiyuki Kaneko, Naohiko Suzuki, and Ryo Hirono. "Study on Turning of Non-Axisymmetric Three-Dimensional Curved Surfaces." In ASME 2018 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/imece2018-87377.
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Conventional machining of complex parts having three-dimensional curved surfaces is performed in two steps using a five-axis machining center and a grinding machine. There is a problem with productivity. Therefore, we developed a CNC lathe to cope with high-speed machining. The newly developed CNC lathe has four axes (X1, X2, Z, C). In this machining, the tool on the X axis follows the curved surface synchronously with the rotation angle of the spindle. This cutting method enables machining of the three-dimensional curved surface. By adopting a linear motor for the X axis, high-speed reciprocal motion of the tool is realized, and the machining time has been reduced to approximately 1/30, as compared with the conventional milling process. In this operation, since high-response motion is required for the tool positioning, a certain profile error remains even if repeated control is applied using the linear scale. In the present study, for the purpose of improving the contour accuracy of a three-dimensional curved surface, we report the result of compensation between the profile measurement method of workpiece and the desired profile accuracy. After machining a three-dimensional curved surface by the developed CNC lathe, a line laser displacement sensor is used to measure the workpiece profile on the machine without removing the workpiece. The position of the machining program is measured by synchronizing the controller of the CNC lathe and the line laser displacement gauge. In addition, the desired profile accuracy is improved by compensating for the error between the desired profile accuracy and the measurement result.
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Guo, Xiangyu, and Chabum Lee. "Non-Contact, Continuous, Synchronized, Cosine Error-Free Thickness Profile Measurement by Surface Metrology Tool Path Planning." In ASME 2020 15th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/msec2020-8289.
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Abstract This paper represents the development of a synchronous thickness profile measurement system that measures double-sided thin pipe wall surfaces in a non-contact, continuous, cosine error-free and fast manner (NCCCE-Fast double-side thickness profiles measurement). A pair of capacitive type sensors (CS) placed on the rotary and linear axes scan the inner and outer surfaces of the thin wall. Surface metrology tool path is developed to align the displacement sensors always normal to the double-sided surfaces simultaneously. Because the rotary axis’s rotational error can badly affect thin wall thickness profile measurement accuracy, such error is initially characterized by a reversal method and was compensated for along the rotational direction while measuring the sample. Two measurement target samples (round/oval metal pipe-type thin walls) are prepared. Not only inner/outer surface profiles but also thin wall thickness profiles are obtained. Based on the output data, the circularity and ovality can be calculated, and those results are compared with those obtained by a contact type micrometer at every 6 degrees interval. As a result, the developed thin wall thickness profilometer can provide high precision results, continuous and fast thickness profile scanning and data are acquired for visualization.
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Baglioni, Stefano, Claudio Braccesi, Filippo Cianetti, Antonio Ficola, and Carmelo Anile. "Design of a Biomedical Device Through Non Linear Analysis." In ASME 2015 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/imece2015-51765.
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The most widely accepted hypothesis to explain normal pressure hydrocephalus (NPH) points at the increase of cerebrospinal fluid (CSF) outflow resistance as the fundamental cause. Some clinical and experimental studies do not agree with this hypothesis and suggest that NPH is related to an alteration of the CSF pulse pressure waveform, while intracranial pressure (ICP) mean value has negligible effects. The current treatment of hydrocephalus is based on the first hypothesis and consists in the implantation of CSF shunts. An improved treatment can be obtained by damping the ICP pressure peaks and keeping unchanged the mean value. The target of this work is to design a special ICP regulator valve, that will be implanted in a human body and that must be characterized by a purely mechanical working principle avoiding any electrical equipment (sensors, actuators...). This device is currently patented [1] and in virtue of that the paper will focus only on the general device working principle and design methodology rather than specific data. Since the device must be implanted inside the patient head, the system must satisfy very restrictive requirements: low weight and dimensions in order to avoid possible patient discomfort or obstacles to the normal life activities, in addition, being the valve application place close to a delicate organ such the brain is, the mechanism must be very simple and must reach very high reliability standards (almost zero maintenance and possible failures). The idea is to realize a device in which the hydraulic flow is governed by a spring with variable stiffness with respect to the applied loads (intracranial pressure: characterized by both a mean constant component and by random oscillatory phenomenon). To maximize the valve effect about pressure peaks reduction, the spring will be designed with a strongly non-linear behavior characterized by bistable working principle. The systems that show this properties are innumerable, but according to the author hypothesis to realize a mechanism as simpler as possible the choice done falls into the thin curved plate (shell) category. In particular, the goal is to obtain a plate behavior called “Buckling Behavior”: under determined load conditions the plate geometric configuration must suddenly switch from an equilibrium position to another. The two target parameters which describe this phenomenon are the buckling critical load that is the applied load value for which the plate change the geometric configuration (valve activation point) and the load application point displacement (evacuation pipe opening). The adopted design method is the non-linear analysis developed in a finite element analysis (F.E.A.) environment, by which it is possible to analyze a component behavior also in case of large displacements. To identify the optimal component geometry the load application point displacement versus the acting load was evaluated as function of the main parameters describing the plate profile: plate semi-length, curvature radius and semi-length of the plate plane portion. This work represents only a preliminary study oriented to demonstrate the feasibility in realizing a biomedical valve for fluids pressure control, adopting a thin curved plate with “Buckling Behavior”. Moreover it provides useful information for the designer who wants to realize curved plate with buckling behavior showing the influence of the main geometric parameters on this phenomenon. Further in depth studies oriented to: the spring stiffness regulation for different patients, best material choice and productive process must be accomplished before the device realization.