Academic literature on the topic 'Lever-spring'
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Journal articles on the topic "Lever-spring"
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Fawazi, Noor, Jung-Youn Lee, and Jae-Eung Oh. "A load–displacement prediction for a bended slotted disc using the energy method." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 226, no. 8 (November 29, 2011): 2126–37. http://dx.doi.org/10.1177/0954406211430046.
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A slotted disc spring consists of two segments: a coned disc segment and a number of lever arm segments. In this study, a load–displacement formula for the slotted disc spring is newly developed in the form of energy method by considering both rigid and bending deflections of the two segments. This formula is developed with the aim to further improve the SAE formula which is limited to a straight slotted disc spring. The coned and the lever arm angles of the straight slotted disc spring are the same. They are different for a bended slotted disc spring. Because of this limitation, it is geometrically impractical to employ the SAE formula for a bended slotted disc spring. To achieve the goal of this study, new calculations based on geometric and material properties inputs are developed for a bended slotted disc spring. A firm background study based on the theory of Almen is presented in developing new load–displacement calculations for a bended slotted disc spring.
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Kulik, A. D., A. F. Britachkov, V. A. Tarasenko, A. Ya Publika, S. S. Brodskii, and V. V. Nesvet. "Increasing the reliability of lever-spring type slide valves." Refractories 26, no. 1-2 (January 1985): 106–8. http://dx.doi.org/10.1007/bf01398629.
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Choi, Won-Hong, and Sang-Mok Shin. "The Separating Cover Using an Explosive Bolt and Spring Lever." Journal of the Korean Society for Aeronautical & Space Sciences 45, no. 11 (November 30, 2017): 922–31. http://dx.doi.org/10.5139/jksas.2017.45.11.922.
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Karditsas, Stylianos, Georgios Savaidis, and Michail Malikoutsakis. "Advanced leaf spring design and analysis with respect to vehicle kinematics and durability." International Journal of Structural Integrity 6, no. 2 (April 13, 2015): 243–58. http://dx.doi.org/10.1108/ijsi-11-2013-0044.
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Purpose – The purpose of this paper is to provide sound understanding of the mutual interactions of the major leaf spring design parameters and their effects on both the stress behavior of the designed leaf and the steering behavior of the vehicle. Design/methodology/approach – Finite elements analyses have been performed referring to the design of a high performance monoleaf spring used for the suspension of the front axle of a serial heavy truck. Design parameters like eye type, eye lever, spring rate and arm rate difference have been parametrically examined regarding the stress performance and their influence on the wheel joint kinematics. The effect of each design parameter is exhibited both qualitatively and quantitatively. Findings – Eye lever and eye type affect significantly the wheel joint kinematics and therewith the steering behavior of the vehicle. Spring rate and arm rate difference affect solely the stress performance of the leaf spring. Practical implications – Design engineers may use the outcomes of this research as a guide to achieve optimal leaf spring design ensuring its operational strength in conjunction with accurate steering performance of the vehicle. Originality/value – The international literature contains only few, mostly qualitative data regarding the effect of single design parameters on the leaf spring and the corresponding axle kinematics. The present work contains a comprehensive and systematic study of all major leaf spring design parameters, and reveals their effect on both the stress behavior and the steering behavior of the vehicle qualitatively and quantitatively.
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McHenry, Matthew J. "There is no trade-off between speed and force in a dynamic lever system." Biology Letters 7, no. 3 (December 8, 2010): 384–86. http://dx.doi.org/10.1098/rsbl.2010.1029.
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Lever systems within a skeleton transmit force with a capacity determined by the mechanical advantage, A. A is the distance from input force to a joint, divided by the distance from the joint to the output force. A lever with a relatively high A in static equilibrium has a great capacity to generate force but moves a load over a small distance. Therefore, the geometry of a skeletal lever presents a trade-off between force and speed under quasi-static conditions. The present study considers skeletal dynamics that do not assume static equilibrium by modelling kicking by a locust leg, which is powered by stored elastic energy. This model predicts that the output force of this lever is proportional to A , but its maximum speed is independent of A . Therefore, no trade-off between force and velocity exists in a lever system with spring-mass dynamics. This demonstrates that the motion of a skeleton depends on the major forces that govern its dynamics and cannot be inferred from skeletal geometry alone.
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Chen, Dongliang, Jindong Zhang, Xutao Weng, Yunjian Zhang, and Zhonghui Shi. "Analysis of Stiffness and Energy Consumption of Nonlinear Elastic Joint Legged Robot." Applied Bionics and Biomechanics 2020 (July 14, 2020): 1–10. http://dx.doi.org/10.1155/2020/8894399.
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In order to reduce the energy consumption of the legged robot in walking, this paper designs a kind of nonlinear elastic joint from the flexible variable-stiffness joint based on the mammal walking on the limb and optimizes the leg structure of the legged robot. The motor is rigidly connected to the articulated lever. When the lever is accelerated or decelerated, the elastic unit is introduced. The system can be considered as a special variable-rate elastic system. This paper will study it from theory and simulation experiments. Based on the dynamic analysis, a functional relationship between the output torque and the torsion spring stiffness and between the energy consumption and the torsion spring stiffness was established. By finding the extremum, the two optimum torsional spring stiffness that can minimize the required output average torque and the energy consumed during one cycle of motion were deduced. The results show that using this design in a reasonable position can effectively reduce the energy consumption of the system and can achieve up to a 50% reduction in energy consumption.
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Beiner, L. "Variable-Geometry Motion Control of an Aircraft Door." Journal of Mechanical Design 121, no. 2 (June 1, 1999): 195–99. http://dx.doi.org/10.1115/1.2829443.
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The paper deals with the motion control of an aircraft door hinged at its lower edge. The door opens under the influence of weight, restrained by cross-mounted air springs and dampers. The goal is to mechanically control the motion so as to bring the door in a specified time from rest at a specified initial position to rest at a specified final position, while minimizing the peak force in the dampers. It is shown that such a velocity profile requires to engage the dampers at an optimized position and simultaneously start to modulate the spring moment so that it equals the weight moment at the final position. A variable-geometry solution is proposed consisting of a mechanical feedback in which the door rotation drives an elongation of the spring levers via bevel gears and screw leads. The associated double two point boundary value problem is solved by casting it into a constrained optimization form, yielding the required damper engagement position, the amount of spring lever extension and the damper lever length. The approach is illustrated by a design example.
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French, M. J., and M. B. Widden. "The spring-and-lever balancing mechanism, George Carwardine and the Anglepoise lamp." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 214, no. 3 (March 1, 2000): 501–8. http://dx.doi.org/10.1243/0954406001523137.
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Two short and direct methods of exact analysis of the spring-and-lever balancing mechanism are presented. It is shown that perfect balance can be achieved by the use of a close-coiled spring whose free length is effectively zero and whose stiffness is chosen appropriately. The two-degree-of-freedom balancing mechanism, commonly seen in desk lamps but useful in many other situations, is then analysed. The treatment is extended to allow for the weight of the components of the mechanism itself. The originator of these devices was George Carwardine, whose patents over the period 1931–35 show the evolution of his ideas on this subject. A short biographical note is included as an appendix.
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Proksch, Roger, and Jason Cleveland. "Quantifying Molecular Forces: Sensitivities and Spring Constants Without Touching a Surface." Microscopy and Microanalysis 7, S2 (August 2001): 862–63. http://dx.doi.org/10.1017/s1431927600030385.
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Recent work has demonstrated the ability to measure forces between and within single molecules using cantilever-based instruments. Force measurements on molecules can provide structural and dynamic information not available with other techniques. Figure 1 shows an example force-distance curve made of lambda digest DNA being stretched by a cantilever, showing the characteristic plateau at 65 pN as the DNA goes through the B-S transition. Implicit in these measurements is a need for carefully quantifying the forces the cantilever is exerting on the single molecule. This requires a low noise system that provides accurate measurements of the cantilever spring constant, cantilever bending, and the relative cantilever-sample separation. We have developed an instrument with several improvements that allows these measurements to be made quantitatively. One component is an improved optical lever that provides an extremely sensitive measurement of the cantilever deflection. A separate sensor measures the position of the moving base of the cantilever and allows thermal drift, piezo scanner hysteresis, and creep effects to be corrected.In force measurements with micro-machined cantilevers the application of Hooke's law (F = −kx) requires two quantities: x, the distance the flexing cantilever moves and the “spring constant” k. The optical lever is the most commonly used method for measuring the deflection of a cantilever.
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Tsunashima, Hitoshi, Takehiko Fujioka, and Masato Abe. "Dynamics of the Mechanical Levitation Control System for Maglev Transport Vehicle (Effect of Guide Wheel Stiffness and Dead Zone Element)." Journal of Robotics and Mechatronics 7, no. 4 (August 20, 1995): 329–35. http://dx.doi.org/10.20965/jrm.1995.p0329.
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This paper describes the effect on ride quality and levitation performance of the guide wheel stiffness and the dead zone element of the permanent magnetic suspension system with the mechanical air gap controller. A vehicle dynamic model with the guide wheel stiffness is constructed and the stability criteria for the levitation is derived. The relation between the dynamic characteristics of the vehicle and control lever ratio is analyzed. Seventeen DOF full model simulation results, where nonlinear characteristics of magnet and primary spring are also considered, indicate that the levitation performance of the vehicle is largely affected by the dead zone in the mechanical air gap controller and that the deterioration of the levitation performance can be suppressed by a large control lever ratio.
Dissertations / Theses on the topic "Lever-spring"
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Francis, Elizabeth Jane. "An investigation into the validation of pedometers to detect foreleg steps in horses (Equus caballus) at walk and trot." Thesis, University of Plymouth, 2018. http://hdl.handle.net/10026.1/11304.
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Background: Current research, surrounding motor laterality at a population level in horses, indicates that in order to stand with the left forelimb in advance of the other, it is achieved by taking a greater amount of steps with the left foreleg than the right foreleg (McGreevy & Thomson 2006; McGreevy et al. 2007); suggesting that pedometers could effectively estimate asymmetry of forelimb locomotion in grazing horses. This novel method of detecting forelimb preference also reduces the likelihood of operator influence and provides an inexpensive objective measure of vertical movement which has the advantage of scoring large sample sizes, avoids single-day anomalies by recording over multiple days and overcomes logistical challenges (Vincent & Sidman 2003; Chan et al. 2005; Silva et al. 2010; Warren-Smith & McGreevy 2010). However in order to determine the reliability and validity of this novel measure the relationship between pedometer data and those derived from direct observation will first need to be assessed (Warren-Smith and McGreevy 2010). Objectives: To determine: (1) if pedometers accurately record equine steps at walk and trot, when compared to video analysis, (2) if alternative positioning of these pedometers affected the accuracy of step detection when compared to video analysis. Method: Five horses each wearing a Yamax Digiwalk SW-200 (spring lever arm pedometer) and a Yamax Power Walker PW-610/611 (piezoelectric pedometer) positioned on the left foreleg (LF), left scapular (LS), chest (C), right scapular (RS) and right foreleg (RF) walked and trotted on a 20m circle 10 times on each rein to yield 100 results for each gait. Video recorded by GoPro Hero 3 Black edition camera positioned on the girth facing the forefeet using the following settings: 180 degree field of view, 720p, 120fps. Both visual and audio data were captured and recorded. Results: Kruskal-Wallis Test on the deviation from actual number of steps per unit for each type of pedometer and the position of the pedometer compared to the actual number of steps taken by both forelegs determined that there is a significant difference (H1= 340.31; P < 0.0001) between readings in walk and also in trot (H1 = 483.49; P < 0.0001). A further Kruskal-Wallis Test on the deviation from actual number of steps per unit for each type of pedometer and the position of the pedometer compared to the actual number of steps taken by individual forelegs determined that there is a significant difference (H = 403.36; p < 0.0001) at walk and also at trot (H = 477.10; p < 0.0001). Conclusion: In summary, the analysis of the pedometer data compared to video analysis indicate that pedometers are not useful for scoring forelimb movements in horses at walk and trot, regardless of positioning.
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Sharef, Hajan, and Marek Potari. "Koncept på ett hydrauliskt mothåll." Thesis, Högskolan i Borås, Akademin för textil, teknik och ekonomi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-12141.
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New technology in the automotive industry is the key to success. Therefore, it is appreciated when people come with new design ways to solve problems. This leads to innovation in the automotive industry that will lead to better and more environmentally friendly cars. This report presents a concept on a pushing counter lever spring which provides the same characteristics of force curve as a diaphragm spring in a pressure plate of a car has. The mechanism is to be used for long-term testing and evaluating clutch pedals. The work describes the development process and the manufacture of a prototype. The program Creo (CAD / 3D) is largely used to construct the components. As are the subprograms Mechanism Design and Simulate to simulate the movement and loads. Excel is a great help at the theoretical calculation of the mechanism and to evaluate the theory behind the concept. The result shows how to simulate a diaphragm spring in the pressure plate in a car for long-term testing of clutch pedals. The goal is to accurately mimic the force curve of a diaphragm spring, in order to design better pedals, and thus reduce the weight on the pedals to in turn reduce fuel consumption to protect the environment is one of the most important factors of all in the automotive industry.
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Augustine, Joyal, and Steven Simons. "Improving the surface finish of the rubber weight plate : Master thesis in mechanical engineering." Thesis, Högskolan i Halmstad, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-45005.
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Flash is the unwanted or excessrubber material that presents on the outersurface of themolded rubber product. This will affect the surface finish; it is a cosmetic defect andit can be removed. It forms because of the leak or the excess molded rubber materialbetween the surface of the mold, typically on the parting line, (Jordan Anderson,2014). The presence of flash will reduce customer satisfaction. There are manymethods to remove the flash. The method is selected according to the degree of flashextension and the location where it occurs.The project aims to design a semi/full automated machine, which helps for having asmooth and fine surface finish of the weight plates. These plates are made up of rubberfor the ELEIKO group. The weight plates have different weights from 10 to 20 kg,but the diameter of each plate stays the same, but the thickness will be different foreach plate. The machine should be designed that removes all the excess rubber andshould smoothen the outer surface of the weight. The purpose of this work is to gainknowledge about different product development methods, respective tools, andtechniques that are used. The machine should be user- friendly, should not becomplicated, should not damage the workpiece (marks or trace of the blade), shouldnot put the employer in danger, and economically feasible.This report presents the progress of designing of the product, product development,methods, and literature study. The designed model can construct in the industry fortheir problem they are faced by the flash. The model is very simple and unique so thateveryone can perform the task without any previous experience. Material alternativeswere evaluated as well as manufacturing possibilities. The designed machine was theoffered for free as means for further research and development. Keywords: flashing, additive manufacturing, Ullman method, Pugh matrix, rubberweight plates, lever arm, smoothening tool.
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Tyo, Brian Matthew. "The Effect of Body Mass Index on Pedometer Accuracy in a Free-Living Environment." 2010. http://trace.tennessee.edu/utk_graddiss/854.
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The purpose of this dissertation was to determine if the New Lifestyles NL-2000 (NL) and the Digi-Walker SW-200 (DW), waist-mounted devices, yield similar daily step counts as compared to the StepWatch 3 (SW), an ankle-mounted device, worn by adults and children in the free-living environment.
For the first study, fifty-six adults (32.7 + 14.5 y) wore the devices for seven consecutive days. There were 20 normal weight, 18 overweight, and 18 obese participants. The NL and DW undercounted (pedometer error) similarly in the normal weight and overweight groups (-15.4% to -18.2%, respectively). However, the DW undercounted more than the NL in the obese group (-32.8% vs -23.9%, respectively). Stepwise regression revealed that both the NL and DW had more error (undercounted more) as a greater percentage steps were accumulated while walking slowly. The DW also had more error with greater BMI. Use of the DW in an obese population will result in twice the error as compared to a normal weight population and thus the DW should not be used to determine relationships between walking volume and adiposity
For the second study, 74 children (13 ± 1.1 y) wore the same devices during one weekday. There were 33 normal weight, 21 overweight, and 20 obese participants. The error was determined for the NL and DW, and the values were similar in the normal weight and overweight groups (-10.8% to -15.4%, respectively). The DW undercounted more than the NL in the obese group (-27.3% vs -8.4%, respectively). The NL was very consistent regardless of BMI category, recording 89.1% (-10.8% error), 89.1% (-10.9% error), and 91.6% (-8.4% error) for the normal weight, overweight, and obese participants, respectively. Stepwise regression revealed that the DW undercounted more in participants with a high weight. Using the DW in obese children of this age group will result in significantly more undercounting when compared to normal weight children. The DW should not be used to determine relationships between walking volume and adiposity in this population. The NL undercounted by ~10%, regardless of BMI category.
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Hegde, Sudarshan. "Pragmatic Design of Compliant Mechanisms using Selection Maps." Thesis, 2013. http://etd.iisc.ernet.in/2005/3308.
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A pragmatic method for designing compliant mechanisms is developed in this thesis, by selecting among existing mechanisms one that may be modified as required. This method complements existing techniques by answering questions of the existence and multiplicity of solutions for the given specifications of a practical problem. The premise for the method is a 2D map that juxta- poses the problem-specifications and the characteristics of compliant mechanisms in a database. The selection of the most suitable mechanisms is similar to Ashby's method of material selection. In our method, stuffiness, inertia, and the inherent kinematic characteristics of compliant mechanisms are analogous to material properties in Ashby's method. These characteristics capture the lumped behavior of compliant mechanisms in static and dynamic situations using spring-lever (SL) and spring-mass-lever (SML) models. The work includes the development of computation- ally efficient methods to compute the SL and SML model characteristics of single-input and single-output compliant mechanisms. Also developed in this work is a method to determine a feasible map by solving the governing equations of equilibrium and several inequalities pertaining to problem- specifications. The map helps not only in assessing the feasibility of the specifications but also in re-designing the mechanisms in predetermined ways to nd multiple solutions, all of which account for practical considerations. The method pays due attention to the overall size, strength considerations, manufacturability, and choice of material. It also enables minimal alterations of the problem-specifications when the user prefers a particular mechanism in the database. All these features are implemented in a web-based Java program with a graphical user interface that can be accessed at http://www.mecheng.iisc.ernet.in/ m2d2/CM design. Six case- studies that include micro machined inertial sensors, miniature valve mechanisms, ultra-sensitive force sensors, etc., are documented in detail to demonstrate the usefulness of the method in practice.
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Varma, Indukuri Harish. "Feasible and Intrinsic Kinetoelastostatic Maps for Compliant Mechanisms." Thesis, 2012. http://hdl.handle.net/2005/3238.
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Despite many advances in the design methods for compliant mechanisms, it is still not possible to know if a set of user-specifications has a solution. Furthermore, practical considerations such as failure limits and manufacturing limitations cannot be easily incorporated into existing methods. To address these issues, we have recently developed the concept of feasible stiffness and inertia maps. This thesis extends the concept of feasible maps and proposes another kind of maps that comprehensively depict the nonlinear kinetoelastostatic behaviour of compliant mechanisms.
Feasible maps drawn as per user-specifications, with compliant mechanisms of the database overlaid on it, instantly inform the reader whether the specifications are feasible; whether the specifications are stringent; whether any mechanisms in the database meet the specifications, and whether any mechanism can be interactively modified to meet the specifications including size, strength and manufacturability. This thesis extends the earlier work on feasible maps by relaxing one condition that all beam segments in a compliant mechanism must retain their relative proportions. This is achieved by using size optimization. Thus, a certain degree of automation is brought into the procedure, which enhances the ease of use of the feasible maps. Illustrative examples are presented and implementation into a software is demonstrated.
A major contribution of this work is the development of the concept of kinetoelastostatic maps of compliant mechanisms with fixed topology, shape, and relative proportions of beam segments in them. The map is drawn on a 2D plot using two non-dimensional quantities, one that captures the response of the mechanism and the other that combines the force, geometry, and material parameters. The map encloses a region that indicates the kinetoelastostatic capability of the mechanism. Another contribution of this work is the observation that the enclosed region can be parameterized using average slenderness ratio of the beam segments. The resulting curves help designers in assessing the capability and limits of a mechanism in terms of geometric advantage, mechanical advantage, normalized output displacement, inherent stiffness, etc. Numerous examples are presented to explain various uses of the non-dimensional maps.
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Dinesh, M. "Design Of Two-Axis Displacement-Amplifying Compliant Mechanisms Using Topology Optimization." Thesis, 2008. http://hdl.handle.net/2005/751.
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This thesis deals with the design of two-axis displacement-amplifying compliant mechanisms (DaCMs) using topology optimization. The two-axis compliant mechanisms considered here are XY positioners and two-axis inertial sensors. A building block approach, with several single-axis DaCMs as building blocks, is used to conceive designs of compliant platforms that provide two orthogonal and independent movement of a common platform. Spring-mass-lever (SML) models of these designs are developed to simplify the analysis and design of the complicated arrangements of building blocks.
The XY positioners designed in this work have perfectly de-coupled motion without compromising on the frequency; the best design of the stage has a displacement amplification of five resulting in the enhanced range of 4.2 % of the mechanism size–a significant improvement from the 1.67 %, the maximum range of the designs reported so far. Nearly 100% improvement is observed in the sensitivity of the two-axis accelerometer as compared with an existing design that occupied the same area.
Multiple prototypes of XY positioners were fabricated on polypropylene sheets using CNC machining; and on spring steel and aluminium using wire-cut electro discharge machining. Mask layouts for two-layer two-axis accelerometers are designed for micro-fabrication using reactive ion etching and wafer bonding.
Conference papers on the topic "Lever-spring"
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Kassem, Saad A., and Yasser H. Anis. "Modeling and Simulation of Hydromechanically Constant Power Controlled Swash Plate Pumps." In ASME 2006 International Mechanical Engineering Congress and Exposition. ASMEDC, 2006. http://dx.doi.org/10.1115/imece2006-14470.
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This paper presents a theoretical study of the performance of constant power operated swash plate pumps equipped with hydromechanical controllers incorporating either pivoted levers or two feedback springs. Mathematical models of these controllers are derived and used to simulate the static and dynamic characteristics of a small pump of 40 cc/rev geometric volume. Results show that the controller with the pivoted lever renders better static and dynamic characteristics compared to the controllers with feedback springs. Results also show that changing the power through varying the lever arm length is preferable than varying the valve spring initial compression, when the dynamic characteristics of the pumps with controllers of pivoted levers are considered. The effect of the valve spring initial compression on the static performance of a pump incorporating a controller with two feedback springs is also investigated.
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Leutwyler, Zachary, Emil Leutwyler, and Neal Estep. "AOV Quarter-Turn Efficiency Models and Validation." In ASME/NRC 2014 12th Valves, Pumps, and Inservice Testing Symposium. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/nrc2014-5031.
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Common quarter-turn (QT) mechanisms used in nuclear plant air-operated valves (AOVs) include scotch yoke, lever, and link-and-lever mechanisms coupled to diaphragms and pistons. QT mechanism efficiency varies as a function of valve position and is a critical design input used to determine AOV margin. Because of the lack of publicly available data of a quality commensurate with “nuclear QA [quality assurance],” Kalsi Engineering, Inc. (KEI), initiated an independent QT-mechanism efficiency test program that includes a number of commonly used actuator manufacturers, models, and sizes based on a survey of U.S. nuclear power plants. The first test specimen was a diaphragm actuator with a lever QT mechanism. The diaphragm rod of the test specimen was instrumented with strain gauges so that a direct measurement of the net actuator force transmitted to the QT mechanism could be measured. In addition to the net thrust, the output torque, diaphragm pressure, and actuator position were measured. Measuring the net thrust, diaphragm pressure, and position allowed the spring rate, spring preload, and effective diaphragm area to be quantified. This test specimen was tested using two different types of bearings at the actuator shaft-to-lever connection. Needle bearings were used to provide torque results for a nearly frictionless QT mechanism, and bronze bearings were used to simulate a more realistic QT-mechanism configuration. Predictions made using the first-principles efficiency model are compared to efficiencies extracted from test. The predicted efficiency using a realistic range for the friction coefficient of the bronze bearings is in good agreement with the extracted efficiencies. Paper published with permission.
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Rai, George, Christopher D. Rahn, Edward Smith, and Conor Marr. "Vibration Isolation Using Continuous Beams." In ASME 2020 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/imece2020-24526.
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Abstract Vibration Isolation involves an inertially coupled system with a mass-lever combination where the inertial forces cancel spring induced forces, thus permitting a high degree of isolation at a relatively low frequency in discrete dynamic systems. This paper shows that the lever combination can be clamped at the root rather than pinned and modeled as a continuous dynamic system. It is theoretically proven that this model can be tuned to achieve isolation with zero displacement, force, and moment transmissibility. The frequency response is calculated based on Euler Bernoulli assumptions for a beam with a tip mass under point force loading. A tip mass equivalent to the mass of the beam can reduce the first isolation frequency by 71% for shear at the root, 72% for moment at the root, and 64% for tip displacement, relative to a cantilever without a tip mass.
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Holgate, Matthew, and Thomas G. Sugar. "Active Compliant Parallel Mechanisms." In ASME 2014 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/detc2014-35668.
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In a novel compliant parallel mechanism, a motor and spring are arranged in a parallel fashion and are connected to a movable lever arm. The motor pushes and pulls on one attachment point and the spring stores and releases energy at a second attachment point. In a non-obvious choice, we do not attach the output link to the commonly thought of end-effector, but to the third link in the planar, parallel mechanism. The new mechanism allows the transmission ratio of the motor to be a function of the output angle and the force applied at the spring. For example, if there are no loads on the spring, the overall gear ratio is lowered, and the output speed can be increased. Conversely, if there are loads on the spring, the overall gear ratio is increased, and the output torque can be increased.
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Yamaguchi, Hideya, and Hidehisa Yoshida. "Linear Friction Damper Consisted of Cylindrical Block and Inclined Lever (Improvement to Avoid Sprag-Slip Problem and Analytical Model to Verify Cause)." In ASME 2011 Pressure Vessels and Piping Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/pvp2011-57073.
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For the passive isolation systems, the ordinary friction damper of constant friction force has performance limitations. This is, because the isolation characteristic declines and the displacement remains apart from the equilibrium position after the disturbance disappears, when the friction force is large. It is known that the above drawbacks are improved when the friction force varies depending on the displacement. The authors have proposed a new type of friction damper in our previous paper. This friction damper uses an inclined lever, which contacts the cylindrical block by means of a rotational spring. The angle of inclination of the lever varies together with the displacement of the cylindrical block. Then, the normal and friction forces on the contact surface vary depending on the displacement. However, “Sprag-slip” vibration occurred in some cases in the experiments. This paper investigates the cause of the vibration and a design to prevent it. Then, an analytical model is proposed to simulate the problem and to estimate the effect of improvement.
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Aydan, Go¨ksu, Ender Cig˘erog˘lu, and S. C¸ag˘lar Bas¸lamıs¸lı. "Application of Tuned Mass Dampers and Lever Type Vibration Isolator to the Quarter-Car Model in Order to Increase Ride Comfort." In ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2010. http://dx.doi.org/10.1115/esda2010-24277.
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In this paper, performance of passive vibration isolators, namely rotational / linear tuned mass dampers (TMD) and lever type vibration isolators (LVI), are investigated under different configurations for optimal ride comfort. TMDs reduce vibration levels by absorbing the energy of the system, especially around natural frequencies with the help of viscous dampers. Two types of TMDs, rotational and linear, are investigated in this study. Although linear TMDs can be more easily implemented on suspension systems, rotational TMDs show better performance in reducing vibration levels. The reason is that, the inertia effect of rotational TMDs is higher than linear TMDs. In order to obtain better results with TMDs, a study on different possible configurations is conducted. A plate, with very small mass, is added between sprung and unsprung masses without changing the original suspension spring stiffness and damping coefficients and acts as a support for in-series TMD applications. Finally, LVIs are implemented to reduce sprung mass acceleration and more satisfactory results are obtained especially around body bounce frequency.
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Dinesh, M., and G. K. Ananthasuresh. "Displacement Amplifying Compliant Mechanisms for Two-Axis High-Resolution Monolithic Inertial Sensors." In ASME 2008 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2008. http://dx.doi.org/10.1115/detc2008-49614.
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Novel designs for two-axis, high-resolution, monolithic inertial sensors are presented in this paper. Monolithic, i.e., joint-less single-piece compliant designs are already common in micromachined inertial sensors such as accelerometers and gyroscopes. Here, compliant mechanisms are used not only to achieve de-coupling between motions along two orthogonal axes but also to amplify the displacements of the proof-mass. Sensitivity and resolution capabilities are enhanced because the amplified motion is used for sensing the measurand. A particular symmetric arrangement of displacement-amplifying compliant mechanisms (DaCMs) leads to de-coupled and amplified motion. An existing DaCM and a new topology-optimized DaCM are presented as a building block in the new arrangement. A spring-mass-lever model is presented as a lumped abstraction of the new arrangement. This model is useful for arriving at the optimal parameters of the DaCM and for performing system-level simulation. The new designs improved the performance by a factor of two or more.
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Salim, Abu, Marney D. Perry, John A. Krogue, and Allen Walker. "A Stable and Fast Operating Door for Use With Pipelines and Launchers / Receivers of Various Diameters." In 2000 3rd International Pipeline Conference. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/ipc2000-205.
Full textAbstract:
The oil and gas pipelines are spread around the world in all nations as complex networks. The increased usage of gas is rapidly increasing this network. These networks are generally made from various diameters of pipes. The pipelines are serviced on as required basis, using pig launcher and receivers to suit the pipe diameter. Pigs of different types may be launched in different sequences, to clean the pipes and to obtain various data related to pipe condition and location. The pig launching and receiving process uses rapid pressure changes in the launcher and receiver and some magnitude of impact may be experienced by the unit. This process also requires frequent access to the launcher/receiver unit. To have an efficient and cost effective usage of the launcher/receiver unit, it is essential to have a door mechanism, which is safe, robust, capable of the above loading conditions, requires minimum service and is easy to use. PECO has recently developed & designed a door, which incorporates ail the above requirements. The door was put to high pressure testing and the test results were so encouraging that PECO named it SafeLock® Closure. The design was developed with gas pipelines in mind. However it is equally applicable to vessels, exchangers and other metal openings where quick, frequent and easy access is required. Safety has been the prime concern through out the design and development process of this closure. Therefore the final product has resulted in a very safe closure. The initial design of the SafeLock® door / closure used a spring load to make it easy in operation. This was removed in the later design. The segmental blocks, usually called C-ring segments, are operated to move in and out of the shell-sub annulus. The closure opening and closing is performed by the use of a single lever arm. This way only one person can operate (open and close) the door / closure. For opening and closing, the lever-arm needs to be rotated less than 40 degree angle. The rotation direction of the lever arm in closing is reverse of that in opening. The door / head can be fully retrieved from the shell-sub and rest by the side of the launcher/receiver to provide complete access to the opening. This door / closure provides quick access to launcher / receiver, pig traps, meter provers, filter vessel, scrubber, scraper, manway to pressure vessel, etc. This closure can be mounted in the vertical or horizontal position. During change of filter elements, launching a pig, quick access to container under pressure, this closure door is designed to provide a safe and fast service. The construction, operation, design details and application of the new closure door are included in this paper and explained with the help of the design diagrams and photographs.
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Bhargav, Santosh D. B., Gaurav Singh, and G. K. Ananthasuresh. "Composite and Multi-Scale Compliant Mechanisms for Manipulation and Mechanical Characterization." In ASME 2013 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/detc2013-12179.
Full textAbstract:
In this paper, we integrate two or more compliant mechanisms to get enhanced functionality for manipulating and mechanically characterizing the grasped objects of varied size (cm to sub-mm), stiffness (1e5 to 10 N/m), and materials (cement to biological cells). The concepts of spring-lever (SL) model, stiffness maps, and non-dimensional kinetoelastostatic maps are used to design composite and multi-scale compliant mechanisms. Composite compliant mechanisms comprise two or more different mechanisms within a single elastic continuum while multi-scale ones possess the additional feature of substantial difference in the sizes of the mechanisms that are combined into one. We present three applications: (i) a composite compliant device to measure the failure load of the cement samples; (ii) a composite multi-scale compliant gripper to measure the bulk stiffness of zebrafish embryos; and (iii) a compliant gripper combined with a negative-stiffness element to reduce the overall stiffness. The prototypes of all three devices are made and tested. The cement sample needed a breaking force of 22.5 N; the zebrafish embryo is found to have bulk stiffness of about 10 N/m; and the stiffness of a compliant gripper was reduced by 99.8 % to 0.2 N/m.
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Krishnan, Girish, and G. K. Ananthasuresh. "An Objective Evaluation of Displacement-Amplifying Compliant Mechanisms for Sensor Applications." In ASME 2006 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2006. http://dx.doi.org/10.1115/detc2006-99345.
Full textAbstract:
Displacement-amplifying compliant mechanisms (DaCMs) reported in literature are mostly used for actuator applications. This paper considers them for sensor applications that rely on displacement measurement, and evaluates them objectively. The main goal is to increase the sensitivity under constraints imposed by several secondary requirements and practical constraints. A spring-mass-lever model that effectively captures the addition of a DaCM to a sensor is used in comparing eight DaCMs. We observe that they significantly differ in performance criteria such as geometric advantage, stiffness, natural frequency, mode amplification, factor of safety against failure, cross-axis stiffness, etc., but none excel in all. Thus, a combined figure of merit is proposed using which the most suitable DaCM could be selected for a sensor application. A case-study of a micro machined capacitive accelerometer and another case-study of a vision-based force sensor are included to illustrate the general evaluation and selection procedure of DaCMs with specific applications. Some other insights gained with the analysis presented here were the optimum size-scale for a DaCM, the effect on its natural frequency, limits on its stiffness, and working range of the sensor.