Academic literature on the topic 'Gravity Hinge'
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Journal articles on the topic "Gravity Hinge"
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Kim, Hyo Young, Jung Jae Kim, Da Hoon Ahn, Dae Gab Gweon, Chan Gon Park, and Dong Pyo Hong. "Analysis of a 3-DOF Rotationally Symmetric Hinge." Applied Mechanics and Materials 284-287 (January 2013): 597–600. http://dx.doi.org/10.4028/www.scientific.net/amm.284-287.597.
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Flexure hinges have been widely used as mechanisms for high precision positioning stages that have a micrometer or nanometer resolution. This paper describes the analysis of a 3-DOF rotationally symmetric hinge for the vertical mask aligner stage. The vertical mask aligner stage was designed to overcome the bending of masks by gravity. In order to align the mask and the wafer, the vertical mask aligner stage has one linear motion and yaw rotating motions (Z, Θx, Θy). The new vertical mask aligner stage will try to use rotationally symmetric hinges. These rotationally symmetric hinges would act as guide mechanisms. However, the exact 6-DOF stiffness analysis of the rotationally symmetric hinge did not use these hinges as guide mechanisms. Therefore, this paper focuses on the stiffness analysis of the rotationally symmetric hinges.
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Fenwick, Richard, Raad Dely, and Barry Davidson. "Ductility demand for uni-directional and reversing plastic hinges in ductile moment resisting frames." Bulletin of the New Zealand Society for Earthquake Engineering 32, no. 1 (March 31, 1999): 1–12. http://dx.doi.org/10.5459/bnzsee.32.1.1-12.
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In a major earthquake the beams in moment resisting frames may develop either reversing or unidirectional plastic hinges. The form of plastic hinge depends upon the ratio of the moments induced by the gravity loading to those induced by the seismic actions. Where this ratio is low the plastic hinges form at the ends of the beams and the sign of the inelastic rotation changes with the direction of sway. These are reversing plastic hinges, and the magnitude of the rotation that they sustained is closely related to the inter-storey displacement. However, when the moment ratio exceeds a certain critical value, unidirectional plastic hinges may form. In this case negative moment plastic hinges develop at the column faces and the positive moment plastic hinges form in the beam spans. As the earthquake progresses the positive and negative inelastic rotations accumulate in their respective zones so that peak values are always sustained at the end of the earthquake. With this type of plastic hinge no simple relationship exists between inter-storey drift and inelastic rotation.
Several series of time history analyses have been made to assess the relative magnitudes of inelastic rotation that are imposed on the two forms of plastic hinge. It is found that with design level earthquakes typically the unidirectional plastic hinge is required to sustain 21/ 2 to 4 times the rotation imposed on reversing plastic hinges, with the curvature ductilities ranging up to 140. These values are appreciably in excess of the values measured in tests using standard details. This indicates that in structures where unidirectional plastic hinges may form, the design displacement ductility and or the allowable inter-storey drift should be reduced below the maximum values currently permitted in the New Zealand codes. The problems associated with the formation of unidirectional plastic hinges can be avoided by adding positive moment flexural reinforcement in the mid regions of the beams. By this means the potential positive moment plastic hinges can be restricted to the beam ends.
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Saenkhum, Nattapon, and Tassanai Sanponpute. "The improvement of an elastic hinge-type torque standard machine in NIMT." ACTA IMEKO 8, no. 3 (September 30, 2019): 36. http://dx.doi.org/10.21014/acta_imeko.v8i3.668.
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<p class="Abstract" align="left">The National Institute of Metrology of Thailand’s (NIMT) strain-controlled elastic hinge-type torque standard machine was designed to cover a measuring range of 1 N·m to 1 kN·m. The elastic hinge was used both at the fulcrum and the hanger of the lever arms. The designed elastic hinge’s thickness, 0.50 mm, caused a higher stiffness than a sheet metal plate of other types of torque machines. The bending moment of all elastic hinges affected the sum of the torque signal on the lever arm that was used to observe the balancing of the lever. The residual torque sensitivity, which was no better than 0.20 mN·m, significantly affected the uncertainty of the low-range torque realisation.</p><p class="Abstract">The calibration and measurement capabilities of the machine were 0.010 % (<em>k</em> = 2) in the measurement range of 10 N·m to 1 kN·m and 0.030 % (<em>k</em> = 2) in the measurement range of 1 N·m to 10 N·m. In the transducer calibration, the influence of the random bending moment of the elastic hinge affected the repeatability, reproducibility, and linearity of the low torque measurements. The cause of the bending moment of the elastic hinges was a result of the deviation of the centre of gravity (CG) of the weight on the pan from the reference line. To improve CMCs, separate signal calibrations were selected for this experiment i.e. the left hinge, the right hinge, and the fulcrum. The torque in each signal calibration was combined by software and was used to correct the calibration value of the torque.</p>
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GABRIELE GIONTI, S. J. "SOME CONSIDERATIONS ON DISCRETE QUANTUM GRAVITY." International Journal of Geometric Methods in Modern Physics 09, no. 02 (March 2012): 1260013. http://dx.doi.org/10.1142/s0219887812600134.
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Recent results in Local Regge Calculus are confronted with Spin-Foam Formalism. Introducing Barrett–Crane Quantization in Local Regge Calculus makes it possible to associate a unique Spin jh with an hinge h, fulfilling one of the requirements of Spin-Foam definition. It is shown that inter-twiner terms of Spin-Foam can follow from the closure constraint in Local Regge Calculus.
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Hassan, Soha, Mohamed Sultan, Mohamed Sobh, Mohamed S. Elhebiry, Khaled Zahran, Abdelaziz Abdeldayem, Elsayed Issawy, and Samir Kamh. "Crustal Structure of the Nile Delta: Interpretation of Seismic-Constrained Satellite-Based Gravity Data." Remote Sensing 13, no. 10 (May 15, 2021): 1934. http://dx.doi.org/10.3390/rs13101934.
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Interpretations of the tectonic setting of the Nile Delta of Egypt and its offshore extension are challenged by the thick sedimentary cover that conceals the underlying structures and by the paucity of deep seismic data and boreholes. A crustal thickness model, constrained by available seismic and geological data, was constructed for the Nile Delta by inversion of satellite gravity data (GOCO06s), and a two-dimensional (2D) forward density model was generated along the Delta’s entire length. Modelling results reveal the following: (1) the Nile Delta is formed of two distinctive crustal units: the Southern Delta Block (SDB) and the Northern Delta Basin (NDB) separated by a hinge zone, a feature widely reported from passive margin settings; (2) the SDB is characterized by an east–west-trending low-gravity (~−40 mGal) anomaly indicative of continental crust characteristics (depth to Moho (DTM): 36–38 km); (3) the NDB and its offshore extension are characterized by high gravity anomalies (hinge zone: ~10 mGal; Delta shore line: >40 mGal; south Herodotus Basin: ~140 mGal) that are here attributed to crustal thinning and stretching and decrease in DTM, which is ~35 km at the hinge zone, 30–32 km at the shoreline, and 22–20 km south of the Herodotus Basin; and (4) an apparent continuation of the east-northeast–west-southwest transitional crust of the Nile Delta towards the north-northeast–south-southwest-trending Levant margin in the east. These observations together with the reported extensional tectonics along the hinge zone, NDB and its offshore, the low to moderate seismic activity, and the absence of volcanic eruptions in the Nile Delta are all consistent with the NDB being a non-volcanic passive margin transition zone between the North African continental crust (SDB) and the Mediterranean oceanic crust (Herodotus Basin), with the NDB representing a westward extension of the Levant margin extensional transition zone.
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Kobayashi, Ryosuke, Shinitiro Nishida, and Shintaro Nakatani. "Study of Mars Rover with Hinge Type Center of Gravity Movement Mechanism." Proceedings of Conference of Chugoku-Shikoku Branch 2018.56 (2018): 1307. http://dx.doi.org/10.1299/jsmecs.2018.56.1307.
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Hasan, Mohammad Nurul, Md Noor Islam, and Salma Begum. "Geophysical interpretation of tectonic features in Bangladesh." Journal of Nepal Geological Society 18 (December 1, 1998): 135–41. http://dx.doi.org/10.3126/jngs.v18i0.32205.
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Bangladesh occupies the major part of the Bengal basin. It is mainly a plain fluvi-dieltaic land. Except the eastern and northeastern Tertiary hilly region, the whole country is covered with thick Quaternary sediments.
Tectonic features in Bangladesh, except the eastern and northeastern hilly structures, are hidden under thick cover of sediments. Gravity anomalies dearly show the locations of major subsurface tectonic features of the country, namely a) Himalayan foredeep, b) Rangpur platform, c) Hinge zone, d) Surma basin and e) Bengal foredeep. Magnetic anomalies and the seismic sections also support the gravity results.
Shape, extent and depth of the tectonic features in Bangladesh are interpreted from geophysical data, particularly from the gravity data supported by available geological and drilling information. Interpretation shows that the Rangpur platform, situated in the northwestern Bangladesh, is the shallowest subsurface tectonic feature in the country. The northern part of the Rangpur platform slopes down to the Himalayan foredeep and the southern part to the Hinge zone. The Surma Basin, containing very thick sediments, lies in north-east corner of the country; and the Bengal foredeep, the most extended tectonic feature, occupies the southern deltaic part of the country. The Fold Belt, the only exposed tectonic feature, lies in the eastern and northeastern hilly region of the country.
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Rezavandi, Arash, and Chung C. Fu. "Response of irregular lightly reinforced concrete frame structures in low seismic zones." Advances in Structural Engineering 20, no. 4 (June 29, 2016): 519–33. http://dx.doi.org/10.1177/1369433216655921.
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This article evaluates the performance of lightly reinforced concrete frames in low seismic zones. The frames under evaluation contain vertical and/or plane irregularities and are designed for gravity loads only. Nonlinear time history analysis using scaled ground motions and pushover procedure as a supplemental method is performed in this study. With the adoption of plastic hinge method, damage levels are addressed according to FEMA 356 definitions. The pivot model is considered for hysteresis behavior. The damage stage and number of formed hinges are classified for the beams and columns. A comparison between models demonstrates while the first story height may suffer minor to moderate damage levels even under low seismic intensity, the severity of damage to the asymmetric plan models can be noticeable. The pushover method results are close to that of time history analysis only for the vertical irregular frames without plane irregularity.
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Xu, Hao, Jinglong Han, Haiwei Yun, and Xiaomao Chen. "Calculation of the Hinge Moments of a Folding Wing Aircraft during the Flight-Folding Process." International Journal of Aerospace Engineering 2019 (September 3, 2019): 1–11. http://dx.doi.org/10.1155/2019/9362629.
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A folding wing morphing aircraft should complete the folding and unfolding process of its wings while in flight. Calculating the hinge moments during the morphing process is a critical aspect of a folding wing design. Most previous studies on this problem have adopted steady-state or quasi-steady-state methods, which do not simulate the free-flying morphing process. In this study, we construct an aeroelastic flight simulation platform based on the secondary development of ADAMS software to simulate the flight-folding process of a folding wing aircraft. A flexible multibody dynamic model of the folding wing structure is established in ADAMS using modal neutral files, and the doublet lattice method is developed to generate aerodynamic influence coefficient matrices that are suitable for the flight-folding process. The user subroutine is utilized, aerodynamic loading is realized in ADAMS, and an aeroelastic flight simulation platform of a folding wing aircraft is built. On the basis of this platform, the flight-folding process of the aircraft is simulated, the hinge moments of the folding wings are calculated, and the influences of the folding rate and the aircraft’s center of gravity (c.g.) position on the results are investigated. Results show that the steady-state method is applicable to the slow folding process. For the fast folding process, the steady-state simulation errors of the hinge moments are substantially large, and a transient method is required to simulate the flight-folding process. In addition, the c.g. position considerably affects the hinge moments during the folding process. Given that the c.g. position moves aft, the maximum hinge moments of the inner and outer wings constantly increase.
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Samimi, Razieh, and Seyed Rasoul Mirghaderi. "Buckling Behavior of Through-Plates under Gravity Loads." Applied Mechanics and Materials 105-107 (September 2011): 2183–87. http://dx.doi.org/10.4028/www.scientific.net/amm.105-107.2183.
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Due to the development in the construction and building industry in recent years, numerous methods for safer, easier and more economical design of structures have been studied.Because of the high bi-axial bending capacity and high compressive strength of hollow structural sections, these sections are considered as a popular alternative by designers. Supporting the panel zone demands in the columns and occurring the moment hinge at the ends of beam are too available in column with hollow section. One of the major problems in the way of using these sections is lack of appropriate load path to connect beams to them, which ends up using through-plates. Through-plates are plates that pass through column and beams connect to them at their webs. Consequently these plates should have sufficient stiffness in order to provide enough strength. This paper proceeds to study the buckling behavior of through-plates in moment beam to column connections under gravity loads.
Dissertations / Theses on the topic "Gravity Hinge"
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Moss, Andrew M. "Analysis of a Gravity Hinge System for Wind Turbines." Cleveland State University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=csu1624479290234317.
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Gowda, Sunil. "Combined Effect of Gravity and Lateral Loads on the Formation of Plastic Hinges in Steel Moment Frames With Reduced Beam Sections." OpenSIUC, 2012. https://opensiuc.lib.siu.edu/theses/798.
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Inelastic behavior in steel special moment frames occurs through the development of plastic hinges at locations near the ends of the beam. The main objective of using a reduced beam connection is to force the formation of plastic hinges to be formed at the reduced beam section rather than at the ends of the beam which otherwise would lead to brittle failure of the beam-column connections. The beam has two reduced beam sections, each located at a certain distance from the face of the column, so that the plastic hinges are formed symmetrically at each of this section. When acted upon by lateral loads, the maximum moments occur at the ends of the beam. Therefore, the plastic hinges form at the reduced beam section. However, when a frame is subjected to a combination of gravity and lateral loads, the plastic hinge formation at one of the reduced beam section is not so clear and further analysis has to be done to study the effect. FEMA 350 indicates that the desired plastic hinge location is only valid for beams with gravity loads representing a small portion of the total flexural demand. If gravity demands significantly exceed 30% of the girder plastic capacity then further plastic analysis of the frame should be performed to determine the appropriate hinge locations. The scope of my thesis is mainly to study the combined effect of gravity and lateral loads on the formation of plastic hinges in steel moment frames with reduced beam section connections.
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Barber, Melinda A. "Contribution of Shear Connections to the Lateral Stiffness and Strength of Steel Frames." University of Cincinnati / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1307442652.
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Muhaj, Helisa. "Seismic strengthening of reinforced concrete beams by post-tensioning with anchorages by bonding." Doctoral thesis, 2020. http://hdl.handle.net/10362/103102.
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RC moment resisting frame buildings are one of the most used structural systems in seismic
prone regions. These structures dissipate energy by concentrating the inelastic behaviour (i.e. the damage)
in the plastic hinge regions of the structural elements, that form preferably on the beams ends.
Since Capacity Design has been part of the Design Codes for some years now, some moment resisting
frame buildings have suffered seismic events. Although in most of the cases the ductile performance
of structures has successfully preserved the human lives and no collapse has occurred, deficiencies
regarding the residual capacity and high level of post-earthquake damages have surfaced. The importance
of other solutions that offer higher cost-efficiency and are more resilient has emerged.
Some studies have shown that damage limitation leads to high seismic performance of structural
systems even. This technology was developed at first for application in precast industry, PRESSS
program. Considering the vast amount of existing structures built following the Capacity Design and
the advantages of Damage Avoidance Design, strengthening by post-tensioning with adhesive anchorages
is proposed in this dissertation as a promising intervention for improving the seismic behaviour
of ductile beams. This solution takes advantage of self-centering capacity of unbonded PT strands,
whereas development of bonded anchorages turns this solution suitable for application in residential
/ business frame buildings. The results obtained from four RC beams tested experimentally will be
presented herein, including one reference and three strengthened specimens. The strengthened beams
had reduced residual deformation and enhanced load capacity. The behaviour of the beams tested
experimentally was also studied through numerical analysis. The attained results show that strengthening
by post-tensioning with bonded anchorages represents a suitable intervention for reducing the
impact of seismic events. Reduced damage of structural elements in RC frame after a seismic event
leads to reduced (or absence) cost of repair and building downtime.
Conference papers on the topic "Gravity Hinge"
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Hori, Kohei, Iwao Hayashi, and Nobuyuki Iwatsuki. "Determination of the Tooth Surface Friction Coefficient of a Pair of Mating Gears Based on the Distribution Along the Tooth Profile Precisely Measured With the Gravity Pendulum Method." In ASME 2000 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/detc2000/ptg-14371.
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Abstract A new gravity pendulum method has been proposed in order to precisely measure the tooth surface friction coefficient of a pair of mating gears excluding the bearing loss. In this method, one of the mating gears, which is fixed on a gravity pendulum, is put on the other gear, which is fixed on the ground, and is freely oscillated. The center-to-center distance between the mating gears is kept constant with a flexure hinge mechanism in order to accurately reproduce the relative motion, including rolling and sliding, between the tooth surfaces of practical rotating gears. This method has a great advantage, in that the tooth surface friction co-efficient can be measured in a very small region of the tooth profile, because the initial oscillation amplitude can be set approximately one arc-degree. The distribution of the friction coefficients along the tooth surface has been precisely measured for the exact one pair-, inexact one pair-, and two pair-tooth engagements of an internal gear pair and an external gear pair. Also, the mean values of the distributed tooth surface friction coefficients are calculated by taking the specific sliding between the tooth surfaces into account, and are compared with each other.
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Stellman, Paul, and George Barbastathis. "Actuation Control for Nanostructured Origami™." In ASME 2006 International Mechanical Engineering Congress and Exposition. ASMEDC, 2006. http://dx.doi.org/10.1115/imece2006-16319.
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The fabrication of arbitrary nanostructured devices in 3D space is relevant to many areas of academic and industrial research. From hybrid systems with various physical features to complex 3D optical interconnects, the added functionality gained by 3D nanomanufacturing is promising for the development of novel applications. Nevertheless, the 2D nature of conventional nanomanufacturing processes (i.e. lithography) underutilizes the 3rd dimension since there is currently no infrastructure for 3D. Nanostructured Origami has been proposed [1-3] as one solution to the 3D nanomanufacturing problem. The two-step process consists of first patterning devices and creases (axes of rotation) in 2D followed by a subsequent folding step which actuates the origamis to its final 3D shape. Several actuation mechanisms have been investigated for the folding step, and the folding of simple origamis with an open kinematic chain has been successfully demonstrated experimentally [1-3]. Since the origami segments must be accurately aligned in the 3D folded state, the actuation mechanisms for Nanostructured Origami must be both controllable and repeatable. By developing analytical models of the origamis, control schemes can be simulated to aid in the manufacturing of devices in the laboratory. As an example, a PD control scheme is introduced to achieve set-point position control of an example origami, the corner cube. In the laboratory, a PD control system would be built using a magnetic feedback mechanism. A strip of gold is patterned as a hinge material, and electrical current passes through the wire. In the presence of a magnetic field, the Lorentz force acts upon the origami segments and the resulting torque is given by τ = Cicos α,[Equation] where C is a positive constant, i is the current, and α is the angle between the magnetic field and the current. The PD control law for Nanostructured Origami is equivalent to PD control of an articulated robotic manipulator, with the exception that gravity can be ignored due to the low masses of the membranes. Instead, the stiffnesses of the hinges must be balanced, resulting in a control torque of [Equation] where τ is the vector of joint torques, G is the constraint Jacobian, Kp is the proportional control constant, Kd is the derivative control constant, K is the hinge stiffness matrix, q is the vector of joint angles, and qd is the desired steady-state values of the joint angles. This input torque is applied to the origami device, and the response is calculated by integrating the system's equations of motion [3]. The angular response of the PD controller for the corner cube origami is plotted in Fig. 1, and Fig. 2 shows a schematic of the folding of the corner cube from flat to folded state. Note the well-behaved response for a Kp value of 1500, which demonstrates zero overshoot and a rise time of approximately 15 milliseconds. A plot of the joint torques as a function of time is shown in Fig. 3. This abstract has briefly introduced the use of a PD controller for the actuation of origami devices. For a Lorentz force actuation scheme, we have demonstrated through simulations that the PD control law is stable and robust. If complicated 3D origamis with multiple closed kinematic chains are to be built, detailed control laws must be implemented. Advanced control techniques, such as optimal control, will be investigated to explore improved actuation strategies.
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Karpachevskyy, Taras, and Swavik Spiewak. "Gravity-Assisted, Passive Cancellation of Disturbances for Inertial Sensors." In ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-65775.
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Continuing enhancements in Microsystem Technologies facilitate the development of inertial sensors — accelerometers and gyroscopes — of unprecedented performance to cost ratio and broaden the frontiers of their application. Of particular interest, because of their immunity to ambient disturbances, are sensors equipped with high resolution Electro-Mechanical ΣΔ converters and with a high speed, digital serial signal transmission. The digital circuitry of these sensors reaches the accuracy of 0.02 parts-per-million (ppm). However, the analogue transducers of measured physical quantities into electrical signals inside of the even best inertial sensors are prone to inherent imperfections of analog systems such as nonlinearity, cross-sensitivity, or noise. The best accuracy of these transducers is about two orders of magnitude worse than that of the electrical circuitry. The overall accuracy can be greatly improved by using corrective filters that cancel the effects of imperfections in the analogue transducers. The effectiveness of these filters hinges upon the accuracy of identifying comprehensive models of the analogue transducers. Ambient disturbances, in particular mechanical vibrations, greatly deteriorate the accuracy of identification. Their impact can be attenuated to some extent by using vibration isolation platforms. The effectiveness of attenuation is usually good at the frequencies above 5–10 Hz, however it is poor at low frequencies. This poor attenuation is a significant disadvantage since the low frequency phenomena in inertial sensors have pronounced impact on their suitability for a broad class of applications (e.g., navigation). The presented research focuses on the design of a passive vibration isolation device in which horizontal movement is coupled to tilt in a way that a component of the gravity perceived by the tested inertial sensor effectively cancels out the horizontal acceleration coming from the ambient vibrations.
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Katarya, Amit. "A Novel Passive Riser Tensioning System for a Dry Tree Spread Moored Barge." In ASME 2004 23rd International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2004. http://dx.doi.org/10.1115/omae2004-51043.
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Dry tree risers on floating systems are presently supported either by TLPs or SPARs, both of which have limited payload capacity and no storage. A spread-moored barge having dry trees, storage and integrated drilling facilities has been developed. Model tests were performed for the riser tensioning system used on such a barge for offshore West Africa conditions. The risers are attached to a rectangular platform in a moon pool of the barge. This platform is supported by means of an articulated Rocker Arm System (RAS) located on the vessel main deck. The RAS has built-in counter weights hinged on pedestals fixed to the barge deck. In this arrangement gravity is used to tension the risers and when the barge heaves, the counterweights in the rocker arm system essentially decouple the barge vertical motion from the riser platform. This system provides a heave-restrained platform for dry trees with minimal dynamic loading of the risers. The model tests confirmed the feasibility of the new design. The paper describes the basic components of the gravity tensioning system. The model test set up and results from the model test are shown. Comparison of model test results with a fully coupled analytic model consisting of the barge and articulated tensioning system is also presented.
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Sundar, Vallam, Torgeir Moan, and Jo̸rgen Hals. "Conceptual Design of OWC Wave Energy Converters Combined With Breakwater Structures." In ASME 2010 29th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2010. http://dx.doi.org/10.1115/omae2010-20508.
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Ocean wave energy is one of several renewable sources of energy found in the ocean. The energy in the oscillatory ocean waves can be used to drive a machinery that converts the energy to other forms. Depending on the type and their location with respect the coast and offshore, a number of devices have been and are being developed to extract the wave energy for conversion into electricity. The most common devices are referred to as the oscillating water column (OWC), hinged contour device, buoyant moored device, hinged flap and overtopping device. Particularly popular are OWCs and moored floating bodies. The idea of integrating breakwater and wave energy converters emerged in the Indian wave energy program. Graw (1996) discussed this idea and pointed out the advantage of shared costs between the breakwater and the wave energy device. Because long waves are usually experience stronger reflection at coasts and breakwaters, they provide good conditions for the operation wave energy devices which work efficiently when the reflection is high. There are examples that OWC devices have been installed in water as shallow as 3 m. This paper reviews the options of integrating OWCs with different kinds of breakwaters like the perforated or non-perforated caisson breakwater, and non-gravity piled and floating types. The purpose of each of the concepts will also be highlighted.
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Dibold, M., J. Gerstmayr, and H. Irschik. "Biaxial Vibrations of an Elasto-Plastic Beam With a Prescribed Rigid-Body Rotation." In ASME 2003 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/detc2003/vib-48324.
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In the present work, the development of plastic strains in a flexural beam is studied. The beam is modeled as a Bernoullieuler beam, where large rigid-body rotations and biaxial bending in the small strain regime are studied. The deformation is split into the spatial deformation of a hinged-hinged beam and the movement of the second support. Neglecting axial displacements of the beam, this support moves on a sphere. In the present paper, the latter motion is considered as prescribed. The beam thus is assumed to possess only flexural degrees-offreedom. Such a problem is frequently to be encountered in machine dynamics or robotics. We assume the stiffness of the beam to be considerably lowered due to catastrophic environmental influences, such that the deformations relative to the rigid-body motion, albeit small, reach the plastic regime. The equations of motion are derived by Hamilton’s principle. The potential energy follows from the internal energy due to the elastic part of the deformation and the potential due to gravity. Plastic strains are treated according to the theory of eigenstrains, which act as sources of self-stress upon the linear elastic beam. The biaxial deflections are discretized in space by means of Legendre polynomials. The plastic strains are discretized over length, height and width of the beam by small plastic cells. The plastic strains are computed in every time-step by a suitable iterative procedure. An implicit midpoint rule, which preserves the total energy of the system, is used for integration of the equations of motion. Linear elastic/perfectly plastic behavior is exemplarily treated in a numerical study.
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Li, Ye, and Ragha Rapthadu. "Bending-Additive-Machining Hybrid Manufacturing of Sheet Metal Structures." In ASME 2017 12th International Manufacturing Science and Engineering Conference collocated with the JSME/ASME 2017 6th International Conference on Materials and Processing. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/msec2017-3062.
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The ever-increasing industry innovation demands a paradigm of manufacturing process that is capable of accomplishing multiple tasks on a single component. Majority of structural parts require bending of metal sheets with high degree of accuracy. In many applications bent parts with additional features are sought out for various special purposes. Clearly there is a need calling for the integration of different manufacturing processes to reach a synergistic effect [4, 5]. Traditionally a combination of additive manufacturing and machining is used to alleviate the constraints set forth by machining alone. However this hybrid approach is still constrained by both the limited cutter accessibility and gravity-imposed deposition direction. This paper presents a new Hybrid Manufacturing configuration by combining bending, deposition and machining processes. The major advantage of this new approach hinges on the deliberate use of bending process by providing additional accessibility that is not available on traditional additive – machining setup. Essentially the accessibility issue is overcome by introducing an intermediate bending step so that both metal deposition and removal can be conducted in the process-required orientation. As bending is part of this new hybrid process, springback is also inherent to this new hybrid manufacturing approach. This research incorporates the consideration of both springback compensation and cold hardening effect in the selection of intermediate bending step. Examples are also provided to show the efficacy of this new hybrid manufacturing approach.
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Modarres-Sadeghi, Yahya, Michael P. Pai¨doussis, and Alexandra Camargo. "The Behaviour of Fluid-Conveying Pipes, Supported at Both Ends, by the Complete Extensible Nonlinear Equations of Motion." In ASME 2006 Pressure Vessels and Piping/ICPVT-11 Conference. ASMEDC, 2006. http://dx.doi.org/10.1115/pvp2006-icpvt-11-93796.
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In this paper, the post-divergence behaviour of fluid-conveying pipes supported at both ends is studied using the complete extensible nonlinear equations of motion. The two coupled nonlinear partial differential equations are discretized via Galerkin’s method and the resulting set of ordinary differential equations is solved by Houbolt’s finite difference method and also using AUTO. Typically, the pipe is stable and retains its original static equilibrium position up to where it loses stability by a supercritical pitchfork bifurcation. By increasing the flow velocity, the amplitude of the buckled position increases, but no secondary instability can be observed thereafter, in agreement with Holmes’ results for his simplified model. The effect of different parameters on the behaviour of the pipe has been studied. By increasing the externally applied tension, or by increasing the gravity parameter, the critical flow velocity for the pitchfork bifurcation increases. The pitchfork bifurcation is subcritical if the nondimensional externally imposed tension, is greater than the nondimensional axial rigidity. The solution in the vicinity of the critical point for this case is confirmed to be subcritical, although the fold and the stable non-trivial solution thereafter could not be seen — perhaps because the model is correct to only third-order of magnitude. Dynamic instabilities may be possible for a pipe hinged at both ends but free to slide axially at the downstream end, according to preliminary results.
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Nascimento, Fa´bio, Carlos Levi, Antonio C. Fernandes, Paulo de Tarso Esperanc¸a, and Paulo Sergio Gomes. "A Wave Maker With Active Reflected Wave Compensation System." In ASME 2002 21st International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2002. http://dx.doi.org/10.1115/omae2002-28222.
Full textAbstract:
Important aspects in the studies to assess the dynamic behavior of ocean vessels or structures, like ships or offshore oil platforms is the capability of generating gravity waves under strict laboratory control. Model test techniques are continuously improving and are very much dependent on the good quality waves that could be generated in a basin. Since ocean basins have finite dimensions, the waves reflected by the models, walls and even to some extent by the beaches, may become a critical issue if you need to guarantee accuracy and reliability for the tests. Besides the undesirable pattern of reflected waves within the test area of the basin, these waves come back onto the wave maker, affecting the correct properties of the wave to be generated. Modern wave generator apparatuses are now being equipped with real time control systems that enable them to generate an irregular wave pattern. At the same time they correct their flap motions to compensate re-reflection of waves from the wave-boards. The quality of such a system depends very much on the efficiency of the algorithm to be implemented in it. This paper discusses the development of an effective mathematical model of a control system used in an irregular wave maker–hinged flap type, featuring active wave reflection compensation. An efficient real time algorithm has been selected to run the control system device. The system is able to generate first order irregular waves and detect reflected waves that approach the wave maker by means of wave probes mounted on the face of the flap. The probe registers the input data to be used by the actuator to compensate the incoming wave by controlling the flap motion. Computer simulations obtained for a wave-maker in a flume are used to demonstrate the efficiency of each step of the theory and the overall accuracy of the compensation system.