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Laing, Kara Louise. "Non-linear deformation of a helical spring." Thesis, University of East Anglia, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.323220.
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Durickovic, Bojan. "Waves on Elastic Rods and Helical Spring Problems." Diss., The University of Arizona, 2011. http://hdl.handle.net/10150/202750.
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This work examines problems in the statics and traveling wave propagation on uniform elastic rods with constant curvature and torsion, i.e. a straight rod and a helical rod. The first set of problems concerns planar traveling loop-like waves on intrinsically straight rods. It is shown that loops with compact support can exist on homogeneous rods with a nonlinear constitutive relation, where the strain-energy density contains a quartic term. Next, the effect of heterogeneity in the material properties on the shape of the loop is examined using a homogenization method. The second set of problems deals with a system consisting of a helical spring with a force and a torque applied along the helix axis. First, an overview is presented of problems of finding the stresses given the strains, or vice-versa, assuming that the elastic parameters of the spring are known. Then, the inverse problem is examined, where both stresses and strains are measured, and optimal elastic parameters within the linear consitutive model are sought. Various forms of measured strains are considered. Finally, the special problem with zero axial torque is considered, and criteria when the spring overwinds with a tensile axial force applied are established.
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Porteiro, John L. "Spring Design Optimization With Fatigue." Scholar Commons, 2010. https://scholarcommons.usf.edu/etd/1742.
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The purpose of this work is to look into the fundamental issues regarding spring design and develop a new, easy to use software program that would allow for optimal, flexible spring designs. Most commercial programs that address this function are basic and do not allow the designer much control over the variables hindering design. This is so because most programs start from the premise that the spring is a general purpose part of the system or that other design parameters can be altered to accommodate the chosen spring. In cases where this is not so, such as in hydraulic cartridge valves, where the geometric constraints are severe, spring design may be a cumbersome process. This is particularly true when fatigue life is taken into account.
The solution chosen here is to tailor the software application to these particular design constraints, incorporating some ideas about spring optimization. In addition to this, a concerted effort was made to make the subject more accessible to the engineers using the program by automating the more technical aspects of the process allowing the designers to make intelligent decisions based on how the variables would affect design. To this end currently existing software was evaluated to determine where it was lacking and a new program was written and painstakingly tested. Finally, it was used to correct flaws identified in existing springs.
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Forrester, Merville Kenneth. "Stiffness Model of a Die Spring." Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/32249.
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The objective of this research is to determine the three-dimensional stiffness matrix of a rectangular cross-section helical coil compression spring. The stiffnesses of the spring are derived using strain energy methods and Castiglianoâ s second theorem.
A theoretical model is developed and presented in order to describe the various steps undertaken to calculate the springâ s stiffnesses. The resulting stiffnesses take into account the bending moments, the twisting moments, and the transverse shear forces. In addition, the springâ s geometric form which includes the effects of pitch, curvature of wire and distortion due to normal and transverse forces are taken into consideration.
Similar methods utilizing Castiglianoâ s second theorem and strain energy expressions were also used to derive equations for a circular cross-section spring. Their results are compared to the existing solutions and used to validate the equations derived for the rectangular cross-section helical coil compression spring.
A finite element model was generated using IDEAS (Integrated Design Engineering Analysis Software) and the stiffness matrix evaluated by applying a unit load along the springâ s axis, then calculating the corresponding changes in deformation. The linear stiffness matrix is then obtained by solving the linear system of equations in changes of load and deformation. This stiffness matrix is a six by six matrix relating the load (three forces and three moments) to the deformations (three translations and three rotations). The natural frequencies and mode shapes of a mechanical system consisting of an Additional mass and the spring are also determined.
Finally, a comparison of the stiffnesses derived using the analytical methods and those obtained from the finite element analysis was made and the results presented.Master of Science
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Stebner, Aaron P. "Development, Characterization, and Application of Ni19.5Ti50.5Pd25Pt5 High-Temperature Shape Memory Alloy Helical Actuators." Akron, OH : University of Akron, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=akron1194994008.
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Thesis (M.S.)--University of Akron, Dept. of Mechanical Engineering, 2007."December, 2007." Title from electronic thesis title page (viewed 02/22/2008) Advisor, D. Dane Quinn; Co-Advisor, Graham Kelly; Department Chair, Celal Batur; Dean of the College, George K. Haritos; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.
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Williams, Eric Andrew. "The Development of Actuators for the Whole Skin Locomotion Robot." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/46786.
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The Whole Skin Locomotion robot propels itself using a motion similar to the cytoplasmic streaming exhibited by an amoeba. In the robot there are embedded ring actuators which evert the material of the robot to produce forward motion. The robot benefits from a highly flexible exterior allowing it to squeeze into constricted passageways or collapsed structures. The development of actuators for such a motion is performed by a shape memory alloy composite actuator. Unlike a typical composite model which utilizes a homogenization of fiber and matrix properties our model is developed for line loads produced in individual shape memory alloy wires onto the rod structure. The load vectors are determined in the deformed configuration of the actuator to account for the highly deformed actuator profiles that would be seen in operation. Also the load requirements for such actuators are developed in terms of the constriction forces and functional design limits are established. In addition, a helical spring backbone design is considered and stiffness properties for general helical springs are determined. The contact of spring coils is included in the analysis and a coupled constitutive model is developed for the spring when coils are in contact. The static design of helical springs for use in the actuators is performed and deformation and load restrictions are determined for subsequent design efforts.Ph. D.
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Nekoksa, Pavel. "Dosedy válcových šroubových tlačných pružin." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-231942.
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This diploma thesis deals with hot-formed helical compression springs. The first part of the thesis describes related problems and determines market potential. Following theoretical part describes the influence of contact line on behaviour of springs and compares it with normative regulations. Methods suitable for determination of helix shape are covered in the next part. The last part focuses on practical measurement, in which the change of helix shape during manufacture was observed. The main output of this diplomat thesis is suggestion of measures that should contribute to both optimization of manufacture and verification of FEM model.
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Hegana, Ashenafi B. "Low Temperature Waste Energy Harvesting by Shape Memory Alloy Actuator." University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1461631046.
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Silva, Rafael de Oliveira [UNESP]. "Atenuação de vibrações em sistemas que utilizam molas de liga de memória de forma." Universidade Estadual Paulista (UNESP), 2017. http://hdl.handle.net/11449/150444.
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Diversos estudos relacionados à atenuação de vibrações utilizando materiais inteligentes vem sendo amplamente explorados no meio acadêmico. Neste âmbito, as Ligas de Memória de Forma (LMF) se destacam por apresentarem dissipação de energia vibratória devido ao seu comportamento histerético promovido pelo efeito pseudoelástico. No presente trabalho, dois sistemas com um e dois graus de liberdade, contendo mola helicoidal de LMF como elemento resiliente, são implementados numericamente para demonstrar a atenuação de vibrações ocasionada pelas transformações de fase presentes no material. Para cada um dos sistemas mecânicos investigados, dois modelos termomecânicos são confrontados numericamente visando a obtenção das características de cada modelo em representar a atenuação de vibrações dos sistemas submetidos à carregamentos termo-mecânicos. O trabalho termina comentando as potencialidades da proposta apresentada, discutindo as facilidades e dificuldades encontradas na sua implementação e apontando para o desenvolvimento de futuros estudos.
Several studies regarding the vibration attenuation using intelligent materials have been widely explored in the academic world in engineering. In this context, the shape memory alloys (SMAs) exhibit vibratory energy dissipation due to their hysteretic behavior caused by the pseudoelastic effect. In the present work, two systems with one and two degrees of freedom, containing a SMA helical spring as a resilient element, are numerically implemented to demonstrate the vibration attenuation of the system caused by the phase transformations present in the SMA spring. For each considered mechanical systems, two thermomechanical models are numerically confronted in order to obtain the characteristics of each model in representing the vibration attenuation of the systems submitted to thermo-mechanical loads. This work is concluded presenting the potentialities of the design methodology proposed and future developments to be implemented.
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Silva, Rafael de Oliveira. "Atenuação de vibrações em sistemas que utilizam molas de liga de memória de forma /." Ilha Solteira, 2017. http://hdl.handle.net/11449/150444.
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Orientador: Gustavo Luiz Chagas Manhães de AbreuResumo: Diversos estudos relacionados à atenuação de vibrações utilizando materiais inteligentes vem sendo amplamente explorados no meio acadêmico. Neste âmbito, as Ligas de Memória de Forma (LMF) se destacam por apresentarem dissipação de energia vibratória devido ao seu comportamento histerético promovido pelo efeito pseudoelástico. No presente trabalho, dois sistemas com um e dois graus de liberdade, contendo mola helicoidal de LMF como elemento resiliente, são implementados numericamente para demonstrar a atenuação de vibrações ocasionada pelas transformações de fase presentes no material. Para cada um dos sistemas mecânicos investigados, dois modelos termomecânicos são confrontados numericamente visando a obtenção das características de cada modelo em representar a atenuação de vibrações dos sistemas submetidos à carregamentos termo-mecânicos. O trabalho termina comentando as potencialidades da proposta apresentada, discutindo as facilidades e dificuldades encontradas na sua implementação e apontando para o desenvolvimento de futuros estudos.
Mestre
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Grando, Denilson. "Modelagem de vagão ferroviário em sistema multicorpos e avaliação do comportamento dinâmico em via tangente com desnivelamento transversal periódico." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/18/18149/tde-27092013-100120/.
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Este trabalho utiliza a técnica de modelagem de sistemas multicorpos para analisar o comportamento dinâmico de um vagão ferroviário de carga, trafegando sobre via tangente com desnivelamento transversal periódico. O estudo exibe a modelagem dos principais vínculos deste sistema, como o contato entre o prato e o pião, molas helicoidais e sistema de amortecimento de atrito seco da suspensão primária. A modelagem do contato entre o prato e o pião sugerida, é baseada em um modelo de elastic foundation, e utiliza a característica geométrica dos corpos em contato. O modelo dinâmico de atrito desenvolvido possui atuação bidirecional, sendo utilizado nos elementos dissipativos da suspensão. A matriz de rigidez das molas helicoidais da suspensão primária é obtida utilizando o Triedro de Frenet-Serret e o Segundo Teorema de Castigliano. O modelo matemático, confeccionado com a ferramenta de modelagem ADAMS/Rail, é composto por 90 corpos rígidos e uma caixa flexível e possui 210 graus de liberdade. A comparação dos resultados obtidos na identificação modal experimental e nas análises do modelo comprovou que as hipóteses adotadas na modelagem são aceitáveis, reforçando a utilização dos modelos multicorpos na análise dinâmica do veículo guiado. A variação da velocidade de tráfego do veículo, sobre diferentes comprimentos de irregularidade da via, proporcionou os resultados para confecção dos mapas de resposta dinâmica. Esses mapas foram traçados para o ângulo rolagem, alívio das forças no contato roda-trilho e razão L/V no rodeiro de ataque, e identificaram as regiões mais sensíveis para a rolagem harmônica. A rolagem e torção da caixa foram identificados como os movimentos principais do veículo, quando em tráfego em via com desnivelamento transversal periódico. O conjunto de prato e pião gasto aumentou a faixa de velocidade indicada como crítica para a rolagem, piorando os resultados para velocidades mais baixas. O aumento do amortecimento da suspensão primária, por meio da inclinação do lenoir link, diminuiu os valores de rolagem e do alívio em comparação ao caso nominal. A utilização do ampara-balaço de contato constante propiciou a diminuição do ângulo de rolagem, alívio das forças e da razão L/V do rodeiro na região de ressonância. O aumento do amortecimento deste vínculo, devido à mola elastomérica, proporcionou resultados ainda melhores e indicou que a alteração das características da suspensão secundária pode reduzir a amplitude do movimento de rolagem harmônica. A metodologia de análise do comportamento dinâmico proposta, através dos mapas de resposta, pode auxiliar na determinação das faixas críticas de velocidade de um vagão ferroviário de carga, no tráfego em vias cujas características típicas das irregularidades são conhecidas. Empresas do setor ferroviário podem aplicar este método no projeto de novos vagões, bem como no estudo da velocidade crítica de determinada frota já em operação.This study uses the multibody system modeling techniques to analyze the dynamic behavior of a railway freight wagon, traveling over tangent track with periodic cross level defect. The study shows the modeling of the main links of the system, as the center plate contact, helical springs and dry friction damper. The suggested modeling of the center plate contact is based on an elastic foundation model, and uses the geometric characteristic of these bodies. The dynamic friction model developed is bidirectional, being used in the dissipative suspension elements. The stiffness matrix of the helical springs is obtained using the Frenet-Serret trihedral and the Second Castigliano Theorem. The mathematical model, developed with the software ADAMS/Rail, is composed of 90 rigid bodies and a flexible car body and has 210 degrees of freedom. A comparison of results obtained in experimental modal identification and analysis of the mathematical model showed that the assumptions made in modeling are acceptable, reinforcing the use of multibody models in dynamic analysis of rail vehicles. The traffic speed variation on different lengths of track irregularity provided the results to make the dynamic response maps. These maps were drawn to roll angle, vertical force in the wheel-rail contact and wheelset L/V and identified the most sensitive regions to harmonic roll. The roll and torsion of the car body were identified as the main movements of the vehicle, when traveling over tangent track with periodic cross level defect. The use of worn center plate increased the critical speed range to the roll motion and decreases the performance for slower speeds. The increase in the damping of the primary suspension, through the lenoir link inclination, decreased the rolling angle and wheel lift in comparison to the nominal case. The use of constant contact side bearer reduced the roll angle and wheelset L/V ratio and increased the vertical load on wheels in the resonance region. The use of elastomeric side bearer provided even better results indicating that changes of the secondary suspension characteristics can minimize the movement of harmonic roll. The methodology for analyzing the dynamic behavior, through the proposed response maps, can assist in determining the critical speed ranges of a railway freight wagon running over a track whose typical irregularities characteristics are known. Companies in the rail industry can apply this method in the design of new cars, and study the critical velocity of a given railway fleet already in operation.
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Leech, Andrew R. "A study of the deformation of helical springs under eccentric loading." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1994. http://handle.dtic.mil/100.2/ADA283448.
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Ward, A. P. B. "Analysis and use of resonance in the fatigue testing of helical springs." Thesis, Swansea University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.639343.
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This work concerns the use of resonance, in a proposed test designed to rapidly determine the fatigue life of coil-springs. A method is described whereby any number of the lower natural frequencies and corresponsing mode-shapes, of a coil-spring, constrained by a variety of simple boundary-conditions, may be determined. A method which uses the predicted natural mode-shapes is described, whereby an index of stress, corresponding to the rate of fatigue damage to the coil-spring, resulting from: resonance, the application of opposing static longitudinal forces to the ends of the spring, and residual stresses, may be determined. The predicted stress is used, to determine the most useful of the classes of natural modes, for use in the proposed test of fatigue life, and a method whereby the fatigue life of a spring, resonating in this mode, may be determined. A jig has been designed to hold a spring of largely arbitrary geometry, in this mode of resonance, such that sufficient stress is induced in the wire, to exceed the endurance limit of the material of the spring's wire, for sufficient time to cause failure by fatigue. This includes a method for the application of opposing static longitudinal forces to the ends of the spring, should this be required to supplement the alternating stress caused by resonance.
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Smith, Brice Christopher 1976. "Geometric and elastic properties and mechanical phase separation phenomena in self-assembling mesoscopic helical springs." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/29610.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2003.Includes bibliographical references (p. 279-300).
Helical ribbons with pitch angles of either 11⁰ or 54⁰ self-assemble in a wide variety of quaternary surfactant-phospholipid/fatty acid-sterol-water systems. In all of the systems studied, the thermodynamically stable state for the sterol is plate like mono-hydrate crystals. However, the sterol is typically found to pass through a serious of metastable intermediates from filaments to helical ribbons to tubules before reaching the stable crystalline state. In the present work, we chose to focus on helical ribbons formed in the Chemically Defined Lipid Concentrate (CDLC) system. These helices typically have radii on the order of a few to a few tens of microns and lengths on the order of hundreds of microns. By tethering to these mesoscopic helical ribbons using Devcon 5-Minute Epoxy®, we have been able to elastically deform them, and thus examine their response to uniaxial tension. For small deformations, the low pitch helices behave like linear elastic springs with a spring constant for a typical example measured to be (4.80 +/- 0.77) x 10-6 N/m. From the observed spread in helix dimension, our theory predicts a corresponding range of spring constants for the structures of 10-7 to 10-4 N/m allowing, in principle, a great range of forces to be examined. Under larger tensions, both low and high pitch helices have been observed to reversibly separate into a straight domain with a pitch angle of 90Ê» and a helical domain with a pitch angle of (16.5 +/1 1.3)⁰ for the low pitch or (59.6 +/- 1.7)⁰ for the high pitch. Using a newly developed continuum elastic free energy model, we have shown that this phenomena can be understood as a mechanical phase transition of first order.
(cont.) From this analysis, we have also been able to determine all of the parameters within our model, and to show that it is capable of self-consistently and quantitatively explaining all of the observed properties of these self-assembled helices.
by Brice Christopher Smith.
Ph.D.
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Ilzhöfer, Bernd [Verfasser], and A. [Akademischer Betreuer] Albers. "Untersuchung zur Optimierung schraubenförmiger Druckfedern = Investigation on the Optimization of Helical Springs / Bernd Ilzhöfer ; Betreuer: A. Albers." Karlsruhe : KIT-Bibliothek, 2021. http://d-nb.info/1235072630/34.
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Chen, Xiaofei Verfasser], Markus [Akademischer Betreuer] [Albrecht, and Iris Marga [Akademischer Betreuer] Oppel. "Helicate-based cation triggered molecular springs / Xiaofei Chen ; Markus Albrecht, Iris Marga Oppel." Aachen : Universitätsbibliothek der RWTH Aachen, 2019. http://d-nb.info/1195238177/34.
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Chen, Xiaofei [Verfasser], Markus [Akademischer Betreuer] Albrecht, and Iris Marga [Akademischer Betreuer] Oppel. "Helicate-based cation triggered molecular springs / Xiaofei Chen ; Markus Albrecht, Iris Marga Oppel." Aachen : Universitätsbibliothek der RWTH Aachen, 2019. http://d-nb.info/1195238177/34.
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Velazquez-Guerrero, Ramiro. "Contribution to the Design and Implementation of Portable Tactile Displays for the Visually Impaired." Diss., Université Pierre et Marie Curie (Paris 6), 2006. http://hdl.handle.net/10919/71591.
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This thesis explores the design, implementation and performance of a new concept for a low-cost, high-resolution, lightweight, compact and highly-portable tactile display. This tactile device is intended to be used in a novel visuo-tactile sensory substitution/supplemen-tation electronic travel aid (ETA) for the blind/visually impaired.Based on the psychophysiology of touch and using Shape Memory Alloys (SMAs) as the actuation technology, a mechatronic device was designed and prototyped to stimulate the sense of touch by creating sensations of contact on the fingertips.The prototype consists of an array of 64 elements spaced 2.6 mm apart that vertically actuates SMA based miniature actuators of 1.5 mm diameter to a height range of 1.4 mm with a pull force of 300 mN up to a 1.5 Hz bandwidth. The full display weights 200 g and its compact dimensions (a cube of 8 cm side-length) make it easy for the user to carry. The display is capable of presenting a wide range of tactile binary information on its 8 x 8 matrix. Moreover, both mechanical and electronic drive designs are easily scalable to larger devices while still being price attractive.Human psychophysics experiments demonstrate the effectiveness of the tactile information transmitted by the display to sighted people and show feasibility in principle of the system as an assistive technology for the blind/visually impaired.
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SANTIAGO, José Joelson de Melo. "Comportamento térmico e mecânico de molas helicoidais de liga com memória de forma Ni-Ti obtidas por fundição de precisão." Universidade Federal de Campina Grande, 2018. http://dspace.sti.ufcg.edu.br:8080/jspui/handle/riufcg/1921.
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Em muitas situações de projeto em sistemas mecânicos deseja-se rigidez e ao mesmo tempo uma certa flexibilidade. Nesses casos, as molas são elementos interessantes, por isso esses componentes foram bastante estudados. Em paralelo, visando ampliar as possibilidades, novos materiais têm se desenvolvido, a exemplo de materiais funcionais, como é o caso das ligas com memória de forma (LMF). As molas helicoidais fabricadas a partir de LMF são componentes promissores para aplicações como atuadores/sensores, pela capacidade de recuperar grandes deformações elásticas e pseudo-plásticas. Atualmente esses componentes são obtidos em sua maioria através da conformação de fios, a frio ou a quente, e tem aplicação consolidada no campo biomédico, porém no campo industrial as aplicações comerciais ainda são limitadas. Neste cenário, utilizar a fundição de precisão para este tipo de componente pode ampliar as possibilidades e aumentar as aplicações em diversos setores. Por outro lado, é de amplo interesse entender a relação entre as propriedades mecânicas e as configurações geométricas destes elementos. Neste contexto, o principal objetivo deste trabalho é a caracterização térmica e mecânica de molas helicoidais de LMF Ni-Ti (MLMFNiTi) com diferentes configurações, produzidas pelo processo de fundição de precisão, empregando a fusão por indução com injeção por centrifugação (FIC) em moldes cerâmicos. Os resultados obtidos mostraram que as molas produzidas apresentaram transformação de fase característica dos fenômenos de superelasticidade (SE). Por meio dos ensaios mecânicos constatou-se que as molas suportaram, no geral, deformações de até 70%. Os parâmetros dimensionais influenciaram o comportamento mecânico para o qual o aumento do passo e do diâmetro do fio fizeram aumentar a força aplicada para submeter as molas as mesmas deformações. Dessa forma, as molas produzidas apresentam características funcionais adequadas para potencializar aplicações industriais a partir de LMF Ni-Ti.
In many situations of design in mechanical systems one wants rigidity and at the same time a certain flexibility. In these cases, the springs are interesting elements, so these components were well studied. In parallel, in order to expand possibilities, new materials have been developed, such as functional materials, such as shape memory alloys (LMF). Helical springs made from LMF are promising components for applications such as actuators / sensors, for the ability to recover large elastic and pseudo-plastic deformations. Currently, these components are mostly obtained through wire forming, either cold or hot, and have consolidated application in the biomedical field, but in the industrial field commercial applications are still limited. In this scenario, using precision casting for this type of component can expand the possibilities and increase the applications in several sectors. On the other hand, it is of broad interest to understand the relation between the mechanical properties and the geometric configurations of these elements. In this context, the main objective of this work is the thermal and mechanical characterization of LMF Ni-Ti helical springs (MLMFNiTi) with different configurations, produced by the invesment casting process, using induction fusion with centrifugal injection (FIC) in ceramic molds. The obtained results showed that the produced springs presented phase transformation characteristic of the phenomena of superelasticity (SE). Through the mechanical tests it was found that the springs generally supported deformations of up to 70%. The dimensional parameters influenced the mechanical behavior for which the step increase, and the wire diameter increased the applied force to subject the springs to the same deformations. Thus, the springs produced have functional characteristics suitable to enhance industrial applications from LMF Ni-Ti.
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Miazaki, Marcio. "Controle de vibrações em rotores flexíveis utilizando molas helicoidais de liga com memória de forma." Universidade Estadual Paulista (UNESP), 2017. http://hdl.handle.net/11449/152328.
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Este trabalho apresenta uma proposta de utilização de molas helicoidais de liga com memória de forma presentes em rotores flexíveis para a atenuação dos deslocamentos laterais decorrentes de forças de perturbação, notadamente das forças de desbalanceamento. Num primeiro momento, o trabalho apresenta os principais modelos constitutivos de ligas com memória de forma (LMF), onde o princípio de funcionamento deste tipo de material é demonstrado por meio de simulações numéricas, e os resultados obtidos são confrontados com dados disponíveis na literatura. Discute-se também a questão da utilização de um modelo mais simplificado para representar o comportamento da liga para diferentes carregamentos termomecânicos. Dois modelos termomecânicos são confrontados numericamente visando representar adequadamente o comportamento termomecânico da LMF durante as transformações de fase. O trabalho evolui para a construção do modelo matemático via elementos finitos de rotores flexíveis contendo molas helicoidais de LMF e por fim apresenta um conjunto de simulações numéricas para comprovar a eficiência e a potencialidade do procedimento teórico formulado. O trabalho termina comentando as potencialidades da proposta apresentada, discutindo as facilidades e dificuldades encontradas na sua implementação e apontando para o desenvolvimento de futuros estudos.
This work proposes shape memory alloy helical springs present in flexible rotors for the attenuation of lateral displacements mainly caused by unbalance forces. This work presents some constitutive models of shape memory alloys (SMA). The principle of operation of this type of material is demonstrated by numerical simulations and the results obtained are compared with data available in the literature. The present work investigates the use of a simplified model to represent the behavior of the SMA for different thermomechanical loads. Two thermomechanical models are numerically confronted in order to represent properly the thermomechanical behavior of the SMA during the phase transformations. Based on the finite element model of flexible rotors containing helical springs of SMA, the efficiency and the potentiality of the theoretical procedure are shown through numerical simulations. This work is concluded presenting the potentialities of the design methodology proposed and future developments to be implemented.
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XIANG, QIAN, and 項前. "The dynamic analysis of helical spring." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/63252855532183600019.
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Fang, Chung-Kai, and 方重凱. "Dynamic Analysis and Application Of Helical Spring Isolator." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/19771121914418577534.
Full textAbstract:
碩士國立臺灣海洋大學
系統工程暨造船學系
92
Abstract The helical spring possesses 6 degrees of freedom, thus when it is used as an isolator, it can absorb the vibration energy in 6 degrees of freedom. This article aims at discussing the spring constants of the helical spring at 6 degrees of freedom, as well as analyzing its vibration isolation properties. Meanwhile, the spring isolator will be applied to the I-frame of the shaft of a high-speed yacht to isolate the vibration. The isolation effectiveness is analyzed and compared with the experimental values to verify the correctness of the analysis model. The vibration isolation principle of the spring isolator is related to its natural frequency. The natural frequency of the spring is , where k represents the spring constants of the 6 degrees of freedom respectively. When the ratio of vibration frequency of a body over natural frequency is larger than 4, a vibration isolation of over 90% can be achieved. While M is an effective mass supported by the spring isolator, which can be derived by utilizing the superposition principle of beam theory for case of shaft system. By using the computer software Ansys, the numerical simulation of the shaft’s vibration isolation is carried out, and the maximum error between the results of the analysis and the results of the land based experiment is approximately 10%~15%, which was mainly resulting from the assumed value of damping ratio and basically it was proved the feasibility of the computer analysis. The result of I-frame’s vibration reduction experiment conducted on land shows that when the shaft is subjected to impulsive load, the vibration reduction of the vibration acceleration of the base-plate at the first 5 major peak vibration values is between 4.4~59.8dB. When the shaft is under horizontal or vertical excitation force, the first 5 major vibration values of the base-plate have attained a good vibration reduction in the range of 40%~99% in linear acceleration and angular acceleration.
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黃政諺. "Rounded Corner Detection Algorithm for Helical Compression Spring Gauge." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/40818173945964731378.
Full textAbstract:
碩士國立臺灣海洋大學
資訊工程學系
100
Feature detection is widely used in image processing, image recognition and machine vision. Points, lines and regions are usually understood as features. In addition, point features are such as object corners because of their variances are not to be impacted by geometry property, and they are simple to recognize for every man. Hence, more and more individual corner detections are proposed. However, rounded corners are seldom discussed in image recognition, and we find thathelicalcompressionspring is a great object of study. Furthermore, we will propose a rounded corner detection algorithm to detect helical compression spring image. In this paper we propose a rounded corner detection for detecting outside diameter of helical compression spring. The method uses slope comparison to search sites of rounded corner on the helical compression spring image. Through experiments and statistics for computing the outside diameter of spring, this method can steadily detect the rounded corners between 0 degree and 45 degrees, and the deviation of diameter is less than 0.3 percent. Furthermore, it does not have complicated operations in steps, so it can provides stable and accurate results swiftly.
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Liu, Jie-Yu, and 劉潔妤. "Vibration analysis of a helical spring coated with damping layer." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/3x6erv.
Full textAbstract:
碩士國立臺北科技大學
製造科技研究所
98
In this study, the damping material is coated of helical spring. The CAE software is utilized to analyze the dynamic characteristics of the structure. Two damping models are constructed, respectively are coating along the helical wire surface and coating around the wire into the hollow cylindrical. Use the FEM software to analyze the nature frequency and transient response. The vibration reduction effect due to coated damping layer with various coating thickness ratio (Tr), coils ratio (Nc) and positions are evaluated. The vibration reduction is indicated by the decay rate of the amplitude of the free vibration due to initial deformation. The result shows the nature frequency varies with damping mass. The nature frequency decrease with increasing Tr and Nc when coating the helix damping layer. As coating the cylindrical damping layer, the nature frequency increase with increasing Nc at the same Tr because of the axial stiffness is greater than the mass effect, on the other side, the nature frequency decrease with increasing Tr at the same Nc due to the mass effect is greater than the axial stiffness. At the same mass, the vibration reduction with cylindrical coating is greater than the helix coating. When the damping layer position are from the free and fix end, respectively increased Tr and Nc can effectively enhance the vibration reduction.
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CHANG, CHIH-CHUN, and 張智鈞. "Dynamic Finite Element Analysis of Pre-Twisted Cylindrical Helical Spring." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/98563y.
Full textAbstract:
碩士國立臺灣科技大學
機械工程系
99
Following the Wittrick’s twelve differential equations modified with including the pre-twisted angles effect, the present study uses the Rayleigh-Ritz method to develop the one-dimensional finite element equations of motion for the spatial curved beams which can be used in the analysis of pre-twisted helical springs. For the static problems of pre-twisted helical springs, the modified Wittrick’s twelve differential equations can be solved for the exact solutions by the transfer matrix method. The displacement functions in the exact solutions are used to derive the interpolation functions which are used in the computation of the mass and stiffness matrices of the present spring element. The present finite element model is applied in the free vibration analyses of pre-twisted helical springs. To simplify the analysis, constant but different pre-twisted angle is assumed for each element of a pre-twisted helical spring, and the geometric error incurred can be reduced if the number of elements is increased. The present model performance is compared with the analytic solutions of different approaches in the literature. The accuracy and efficiency of the present pre-twisted helical spring element are demonstrated through the numerical results. Also the effects of some parameters, such as boundary condition, number of coils, aspect ratio of the rectangular cross-section and material properties, on the natural frequencies and modes of pre-twisted helical springs are investigated.
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Guo, Yue-Ci, and 郭岳其. "Analysis of the shear correction factor of rectangular helical spring." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/48782143353772387833.
Full textAbstract:
碩士龍華科技大學
機械工程系碩士班
102
Spring in the current daily life and industry play an integral part, are often used in some of the spring force, so the spring can withstand shear and life is currently the most commonly discussed in section, and in the present The textbook formula for shear stress of the spring must add a correction factor, it can be more accurately calculated shear stress of the spring, the most common Wahl correction factor is deduced by a circular cross-section of the spring, is now recognized as the most accurate One formula, but rectangular cross-section of the spring and no clear correction formula, so this paper will use the finite element analysis and mathematical fitting method to infer the rectangular cross-section belonging to a spring correction factor. The results of this study showed that pre-rectangular cross-section of the coil spring torsion angle is not significant influence on the stress, the stress correction formula rectangular cross-section spring spring index can be used to represent the stress of this study are different from the analysis of a rectangular cross-section of the spring and fitting correction formula, and this thesis identify rectangular cross-section of the spring correction factor is in line with the actual situation results from the validation.
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Huang, Gro-drue, and 黃國竹. "The Design of a Variable Pressure Damper Design for Helical Valve Spring." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/09140361384583805293.
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Juang, Yung-Jou, and 莊詠州. "DYNAMIC SIMULATION OF A HELICAL SPRING WITH A CUP DAMPER AND EXPERIMENTAL VERIFICATION." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/72727868282070431248.
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Yueh, Mei-Chen, and 樂美辰. "Mechanical Behavior of A SMA Helical Spring with Two-way Shape Memory Effect." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/6g2mge.
Full textAbstract:
碩士國立臺北科技大學
機電整合研究所
98
In this paper, the processes of making SMA (Shape Memory Alloy) helical springs and training them to be of the two-way SME (Shape Memory Effect) were presented. The helical spring was activated by controlling the electric current applied via the Joule heating. The relationship between the applied current and the resulted temperature was measured. By fixing the SMA spring in certain lengths, the resulting actuation force of the spring upon different current levels were investigated. With the variation of the slope in these load-current and load-temperature diagrams, the rate of phase transformation in the SMA springs could be inferred. The governing equation of the helical spring in axial loading was also derived by using Brinson model. The comparison between the measurement and theoretical modeling was conducted and discussed. When the temperature was raised, the loading on the spring with controlled fixed length increased. However, the increase of the spring force was nonlinear and became saturated as the temperature was above the finish point of the austenite transformation. If the controlled length increased, then the loading increased at the fixed temperature. The slope of the loading curve, i.e. the spring constant, was not always constant due to the possible stress induced martensitic transformation. The transformation tended to lower the slope of the loading curve. By the theoretical formulation in the helical spring, the comparison between the measured results and the computational results showed good correlation.
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Kao, Shih Hung, and 高世浤. "A Study on the Simulation and Heat-treatment parameters of Helical Compression Spring." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/39100196387972199651.
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Peng, Jiung-Shiang, and 彭俊翔. "Free vibration analysis of a non-uniform beam carrying multiple spring-mass systems with mass of each helical spring considered." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/13305671843679845533.
Full textAbstract:
碩士國立成功大學
系統及船舶機電工程學系碩博士班
94
In engineering applications, many dynamic behaviors of structures can be modeled with a uniform or non-uniform beam carrying one or multiple spring-mass systems, so there exist many research reports in this aspect. However, in order to simplify the problem, most of the existing papers do not take the mass of helical spring of the spring-mass system into account. The objective of this paper is to study the vibration characteristics of the uniform or non-uniform beam carrying one or multiple spring-mass systems with the mass of each helical spring considered. To the last end, the helical spring is replaced by a rod and the displacement functions of a typical helical spring and a rod are determined, Then, the compatibility equations of displacement and slope, the equilibrium equations of force and moment at each attaching point, and the equations for the boundary conditions of the two ends of the beam, one may obtain the simultaneous equations. Setting the coefficient determinant of the last equations to be equal to zero, one obtains the frequency equation, and solving the last equation one will obtain one of the natural frequencies. Substituting the associated dimensionless natural frequency coefficient into the last simultaneous equations will determine the integration coefficients of each beam segment concerned. Based on these integration coefficients and the associated displacement function of each beam segment, the corresponding mode shape will be obtained. To confirm the reliability of the theory and computer program developed for this paper, some results obtained from the present method are compared with those obtained from the conventional finite element method. Good agreement between the corresponding results confirms the reliability of theory and computer program developed for this paper.
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KUO, JIAN-XIN, and 郭建炘. "Study of applying piezoelectric material to helical rectangular spring as an energy harvest device." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/8c9gm5.
Full textAbstract:
碩士國立臺北科技大學
機械工程系機電整合碩士班
107
Now the high-tech industry is producing high-precision products, but the vibration of the machine during operation is difficult to avoid, but you can think about how to effectively use the energy that cannot be stored and reused, convert it into another form and use it again, make full use of it. These energy sources. This research topic explores in depth how to design an energy recovery device for the flexible deformation of flexible structures such as compression coil springs. The design method is to apply the piezoelectric material to the rectangular coil spring and the mechanical energy generated by the spring movement. Converted into electrical energy by the piezoelectric effect. The research method uses the finite element analysis software Abaqus analysis. The static analysis is applied to the piezoelectric material with the principal stress orientation of the coil spring. The piezoelectric material has the best angle output effect and the verification of the 1-3 plane and the spiral radial angle of 45 degree. Dynamic analysis explores the resonance and transient response of the system. It is known that the electromechanical coupling constant of the piezoelectric material is equivalent to the mechanical damping characteristic in the undamped state of the system. This characteristic reduces the resonance effect of the system. Finally, the energy recovery efficiency is calculated. If the piezoelectric material is added to the coil, the energy recovery effect is better.
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Ho, Jing Yuan, and 何進淵. "Dynamic Equations for the Helical Spring with a Cup Damper and Static Experimental Verifications." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/92326067061576698181.
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Wang, Shi-Jao, and 王錫昭. "Free vibration analyses of a beam carrying multiple two-dof spring-mass systems with inertia effect of the helical springs considered." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/64592916053056030602.
Full textAbstract:
碩士國立高雄海洋科技大學
輪機工程研究所
97
This paper investigates the free vibration characteristics of a beam carrying multiple two-degree-of-freedom (two-dof) spring-mass systems (i.e., the loaded beam). Unlike the existing literature to neglect the inertia effect of the helical springs of each spring-mass system, this paper takes the last inertia effect into consideration. To this end, a technique to replace each two-dof spring-mass system by a set of rigidly attached equivalent masses is presented, so that the free vibration characteristics of a loaded beam can be predicted from those of the same beam carrying multiple rigidly attached equivalent masses. In which, the equation of motion of the loaded beam is derived analytically by means of the expansion theorem (or the mode superposition method) incorporated with the natural frequencies and the mode shapes of the bare beam (i.e., the beam carrying nothing). In addition, the mass and stiffness matrices including the inertia effect of the helical springs of a two-dof spring-mass system, required by the conventional finite element method (FEM), are also derived. All the numerical results obtained from the presented equivalent mass method (EMM) are compared with those obtained from FEM and satisfactory agreement is achieved. Because the equivalent masses of each two-dof spring-mass system are dependent on the magnitudes of its lumped mass, spring constant and spring mass, the presented EMM provides an effective technique for evaluating the overall inertia effect of the two-dof spring-mass systems attached to the beam. Furthermore, if the total number of two-dof spring-mass systems attached to the beam is large, then the order of the overall property matrices for the equation of motion of the loaded beam in EMM is much less than that in FEM and the computer storage memory required by the former is also much less than that required by the latter.
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Lin, Rung-Ye, and 林榮業. "Study on Improving the AutomaticThree-Dimensional Measurement System for Helical Spring Back Characteristics of Plastic Pipes." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/97241953999848355580.
Full textAbstract:
碩士國立高雄應用科技大學
機械與精密工程研究所
102
Plastic pipes are popular and daily used goods. In order to fabricate a good product, new design concept and quality uniformity are important. Using machine vision technology to analyze the spiral plastic pipe quality such as spring-back property is a good methodology which can facilitate the industries and consumers to trust each other. It also can provide consumers a fair certification in purchasing goods. Therefore, to establish a systematic measurement system has become the research target. This study used the machine vision technology to improve the deficiencies of the measurement logic. Using an external controller to position and move the plastic tube more accurately. In addition, the estimation of fully spring-back time can improve the measure standard to earn consumer trust and recognition. According to the experimental results of this study, the spring-back time prediction is acceptable and the measurement error of plastic pipe radius is within a range of ±0.15mm. By using the ATOS reverse measurement equipment to perform the system verification, the error amount of the average radius of spring-back curvature is 0.014mm which is better than the previous study. The accuracy and stability of the proposed system is verified which help promotion and application in plastic pipe industry.
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Jiang, Guang-Fu, and 簡光甫. "Application of Grey Relational Analysis and ANSYS Package to the Influential Factors on Natural Frequencies of Helical Spring." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/67501710940737311565.
Full textAbstract:
碩士清雲科技大學
機械工程研究所
94
This paper is aimed at the utilization of grey relational analysis model to investigate the influential factors on the dynamic properties of a helical spring during manufacture. With all of the material properties remained unaltered throughout the simulation under the present research, the best parameter level in favor of spring fabrication is determined by means of combinations originated from three different values out of each of five influential geometric parameters, i.e., the helical angle, coil diameter, wire diameter, number of active coils, and the inclined angle. In consideration of the dynamic properties of a spring, the natural frequency of free vibration is quite often the main concern for engineers, since the special attention is centered on the occurrence of resonance which may in turn lead to a catastrophe. Therefore, the natural frequencies are selected as the quality targets in the present research. With a view to bypassing the tedious laboratory task in measuring the natural frequencies related to these combinations, a finite-element model with the aid of ANSYS package is established for the computer simulation instead.
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Yang, Tzu-Hung, and 楊子弘. "The Study of Using Hybrid Shape Memory Helical Spring in the Vibration Reduction of Semi－Active Suspension Platform." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/98650449250197470740.
Full textAbstract:
碩士大葉大學
機械與自動化工程學系
97
In this study, the natural frequency and the associated damping capacity of a platform suspended by four helical springs were investigated at different controlled temperatures. The helical spring was fabricated with multiple layers of pyro condensation polymeric sleeve wrapped outside a superelastic NiTi core which has been heat-treated into helical configuration beforehand. The dynamic characteristics of the hybrid shape-memory helical spring was first investigated experimentally. It was found that the first natural frequency of the spring can be decreased to 50% of the frequency at room temperature when the temperature was raised to 90oC. On the other hand, a decrease in the damping capacity of the spring was found accompanying the increase in temperature. Then, the change in the natural frequency of a platform supported by four helical springs was studied. The prediction of the natural frequency of the first few lower modes of the sprung-mass correlated well with the result from measurement. Moreover, we demonstrated the displacement amplitude of vibration for the platform under eccentric loading of imbalance mass was reduced significantly with the control temperature raised to 90℃.
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(7847843), Rahul Deshmukh. "Influence of geometry and placement configuration on side forces in compression springs." Thesis, 2019.
Find full textAbstract:
A leading cause of premature failure and excessive wear and tear in mechanical components that rely on compression springs for their operation is the development of unwanted side forces when the spring is compressed.
These side forces are usually around 10% - 20% of the magnitude of the axial load and point in different directions in the plane perpendicular to the axis of the spring.
The magnitude and direction of the resultant of side forces varies very non-linearly and unpredictably even though the axial force behavior of the spring is very consistent and predictable.
Since these side forces have to be resisted by the housing components that hold the spring in place, it is difficult to design these components for optimal operation.
The hypothesis of this study is that side forces are highly sensitive to small changes in spring geometry and its placement configuration in the housing.
Several experiments are conducted to measure the axial and side forces in barrel springs and two different types of finite element models are developed and calibrated to model the spring behavior.
Spring geometry and placement are parameterized using several control variables and an approach based on design of experiments is used to identify the critical parameters that control the behavior of side-forces.
The models resulted in deeper insight into the development of side forces as the spring is progressively loaded and how its contact interactions with the housing lead to changes in the side force.
It was found that side-forces are indeed sensitive to variations in spring geometry and placement.
These sensitivities are quantified to enable designers to and manufacturers of such springs to gain more control of side force variations between different spring specimens.
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Tsai, Tsung-Ming, and 蔡宗明. "Optimal Design of helical compression springs." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/75rvvy.
Full textAbstract:
碩士中華大學
機械工程學系碩士在職專班
101
Springs are one kind of mechanic parts. They play the essential roles in the wide scope of devices including the daily appliances, transportation vehicles, and precision machines. Because the fields and purposes of spring applications are very different and also their influence factors of design and manufacturing are numerous. Conventionally, spring design is rather dependent on designer experience and subjective judgment. The design expending is concerned since that many costly trial efforts on time and effort are required. Thus, satisfactory quality of final design outcome cannot be assured. The helical spring is the most wide applied and essential kind of springs. Therefore, in this thesis an approach to the design execution of helical springs is proposed basing on the computer aided method. At first, the much principal theories of helical springs are explained which include geometry and dimensions, spring stress analysis, spring rate, safety and design principles of the static and fatigue aspects, natural vibration frequency, and bulking limit of spring length. Then, soft package Matlab is used to the analysis and evaluation for mechanic behaviors and design safety which have deformation, stress, static and fatigue safety factors, and stability. Besides, the GUI user interface is constructed for the convenience of designer application. Additionally, the optimal analysis function for processing a systematical design improvement of helical springs is also emphasized. The design variables in the investigation have wire diameter, mean coil diameter, pitch, and number of coils. The analysis task is starting from the resulted data of conventional design. By considering the assigned analysis constraints and after performing the optimization calculation, the optimal result of design variables to minimization the spring weight can be attained. Accordingly, material cost of spring making is reduced. The proposed process and obtained result in this study can be applied in the analyses in kinds of spring design. It also expects its application can benefit the design spec satisfaction, design efficiency improvement, and optimal achievement of design objective.
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曾吉禎. "Steady State Analysis of Spinning and Compressing Helical Springs." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/09635960574099920053.
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碩士國立中正大學
機械工程研究所
86
In general machining operations, the cutting tools were held by the draw - in mechanism in the spindle. Insufficient draw - in force would cause poor machining efficiency and quality. So, the draw - in force should be measured peridoically by a set of measurement system after the CNC machine operated for a long time. A set of draw - in force measurement device was designed by Yung - Da Chen in 1996. The force produced by the helical spring in the measurement device balanced the draw - in force produced by Belleville springs. Then the draw - in force produced by Belleville springs. Then the draw - in force could be measured by the displacement variation of the helical spring which was compressing and spinning. General dynamic equations for the springs with circular cross section, varying pitch angle and radius were derived by using Hamilton's Principle and variational method. For a specific spring with constant axial loading and rotation speed, the axial and radial deformation were found in this research. Then, the finite element model built b using finite element analysis software were used to find the axial deformation of the helical spring at specific axial loading and rotation speed. The results we found by FEM analysis and theoretical derivation had the same tendency.
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Lai, Jun-hao, and 賴俊豪. "Static and Dynamic Finite Element Analysis of Cylindrical Helical Springs." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/s69dpu.
Full textAbstract:
碩士國立臺灣科技大學
機械工程系
94
Following the Wittrick’s differential equations modified with including the temperature effect, the present study uses the Rayleigh-Ritz method to develop the one-dimensional finite element equations of motion for the cylindrical helical springs. For the static problems of cylindrical helical springs, the modified Wittrick’s differential equations can be solved for the exact solutions. The displacement functions in the exact solutions are used to derive the interpolation functions which are used in the computation of the mass, stiffness matrices and thermal load of the present spring element. The present finite element model is applied in the static problems and free vibration analyses of cylindrical helical springs, respectively. In the present static analysis, the cylindrical helical springs subjected to uniform temperature change are also considered. The present model performance is compared with that of exact solutions and other finite elements. The accuracy and efficiency of the present spring element are demonstrated through the numerical results.
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Lin, Yi-shin, and 林億鑫. "Vibration Analysis of Fiber-Reinforced Composite Helical Springs with Rectangular Cross Sections." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/56562878736033179333.
Full textAbstract:
碩士國立中興大學
機械工程學系所
103
In this thesis, a finite element model based on two-noded straight beam finite elements, with each node of nine degrees of freedom, is developed to study the dynamic characteristics of helical springs having rectangular cross sections. The helical springs could be made of isotropic materials or fiber-reinforced composite materials. The straight beam element being adopted has included the effects of the transverse shear deformation, torsion, cross-section warping, chordwise curvature, axial, transversal and lateral displacements. The equation of motion of the straight beam element developed in [11] is used, which is derived by employing Hamilton’s principle together with the finite element method. In order to apply the straight beam element to the analyses of the dynamic characteristics of the helical spring, the relation between the spring geometry and the local coordinate systems chosen for straight beam elements must be obtained first. For this purpose, Frenet-Serret formulas [13] are used to derive the coordinate transformation matrix between local coordinate systems of beam elements and global coordinate system. By using the obtained coordinate transformation matrices and considering the continuity of the displacement of the common node between two adjacent straight beam elements, the displacement transformation matrices for these two beam elements are found. With displacement transformation matrices and the mass and stiffness matrices of the straight beam elements, the global mass and stiffness matrices of helical springs are then derived. In the numerical examples, first, the steel helical springs free of constraints and with one of its ends fixed are analyzed. The results are compared with those obtained from commercial software Ansys. It is shown that in both boundary conditions the natural frequencies obtained from the present model and those of Ansys are better in agreement when the width to thickness ratio (b/h) of spring is three. Next, the single-layered and laminated composite helical springs are studied, in which the influences of the width to thickness ratio (b/h), the fiber angle, and the angles of lamination on the natural frequencies and mode shapes are investigated. It is found that for different b/h ratios, natural frequencies of the single-layered composite spring vary irregularly with fiber angles. When analyzing composite laminated springs, only cases with b/h = 3 are considered. For springs with lamination [0/θ/0/-θ]s regardless of being free or fixed at one end, the maximum values of the natural frequencies appear at the angle θ close to 45 degrees. When the spring is fixed at one end, both 2nd and 3rd modes of composite springs with laminations [0/θ/0/-θ]s and [90/θ/0/-θ]s are coupling mode of w and ϕ. When the springs are free, springs of both laminations also have this coupling mode to appear either at 7th or 8th mode.
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Leu, Luo-wen, and 呂洛文. "Study on the Buckling of Helical Compression Springs under Compression and/or Torsion." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/13432844341839828585.
Full textAbstract:
碩士國立臺灣科技大學
機械工程系
98
Based on the equations of motion governing the natural vibration of helical springs subjected to static axial compression and twist, the present study develops the one-dimensional finite element equations of motion for the cylindrical helical springs which can be used in the analyses of buckling loads and natural frequencies. Using the transfer matrix method in the literature this study also solves the buckling loads and natural frequencies of cylindrical helical springs. Both results obtained by the transfer matrix method and the present finite element model are compared to verify the present finite element solutions. The present study also obtains the buckling design charts and frequency design charts of cylindrical helical springs by following the processes used in the literature. In producing the design charts, the present study considers the springs are subjected to axial compression, axial twist, and combined axial compression and twist, respectively. The present results are compared with that in the literature to demonstrate the accuracy and efficiency of the present analysis models. Also the effects of the number of turns of uncompressed helix and the three types of axial loads on the design charts are investigated.
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Chiu, Kuei-chun, and 邱奎鈞. "A Study on Effects of the Geometric Parameters of Helical Springs to the Stiffness and Stress." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/34srw7.
Full textAbstract:
碩士國立臺北科技大學
機電整合研究所
101
Helical springs are an important element in the machinery and widely used. In this study, with CAE software package, one is to study the stiffness and the stress distribution on wire surface of the spring by changing the profile of its cross section, and study the effects of variable pitch and non-cylindrical springs. It is found that when the centroid and area of cross-section is fixed, the Oval-1-H95 is the optimal shape, it reduces the maximal stress by 2%~4% from the reference spring, when the stiffness is identical. On the other hand, when one comes to fix the outer diameter and the volume of springs, the Oval-2 is the optimal shape, it reduces the maximal stress and also strengthens the stiffness. The Oval-2-H85 is the best in reducing the maximal stress, it is 6% lower than that of the reference spring. And the Oval-2-H80 is the best in strengthening the stiffness, it is 15% higher than that of the reference spring, under the premise of lower stress than the reference spring.
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吳明勳. "= Investigation of the nonlinear behaviors of helical springs by considering the friction, coil close and end effect with static verification." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/52557032892327965750.
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Chen, Hung-Chin, and 陳宏晉. "Studies of Free Vibration of Fiber-Reinforced Composite Helical Springs with Circular Cross Sections Using Circularly Curved Beam Finite Elements." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/80223243921081227798.
Full textAbstract:
碩士國立中興大學
機械工程學系所
103
In this thesis, a three-node, 6 degree of freedom per node, curved beam element including the effect of initial curvature and torsion of beam is proposed. In this curved beam element, the lateral and axial displacements, as well as the deformation due to both twisting and shearing of beam are also considered. The curved beam element is employed to analyze circular helical springs with circular cross section, where the springs are made of unidirectional fiber-reinforced composite layers having a preselected set of lamination angles. To study the initial torsion and initial curvature effects in the above curved beam element, the current element is further simplified into other two types of element, a curved beam element without initial torsion and a straight beam element. Using these three types of elements, the effectiveness of curved and straight beam elements to simulate both static and dynamic characteristics of springs then can be evaluated. To ensure the elements being derived and the computer program being developed are correct, first, springs made of an isotropic material are analyzed and the results expressed as the spring constants are compared with the analytical solution derived using the virtual work method. It is found that for the problem being analyzed all three types of elements yield a little bit smaller spring constant values than the analytical one, and the difference of the results between analytical method and any of three types of element is at its largest not exceeding 8%. Next, the vibration characteristics of springs made of an isotropic material are analyzed using these three types of element. The results are compared with those of ANSYS and they are found in good agreement. To study the effect of lamination angle η on the static and dynamic characteristic of springs made of unidirectional fiber-reinforced composite material, composite solid springs with a single lamination angle (or composite solid springs) and laminated composite hollow springs with a particular set of lamination angles (or laminated composite hollow springs) are analyzed. Static analyses of composite solid springs indicate that discrepancies among the three types of elements are more conspicuous when η=〖15〗^o~〖45〗^o, and the values of spring constant seem attain their largest values as η approaches 〖45〗^o. This could be attributed by the bending and twisting deformation coupling of the off-axis composite layer as the coupling effect is strongest when 〖η=45〗^o and one knows that the spring deformed accompanied by both bending and twisting. From dynamic analysis, one finds that all three types of element yield similar trend of natural frequency to η relation. There are a few modes don’t match exactly (like the modes swing directions are different), or have a little bit greater natural frequency discrepancies at certain η values. Finally, the analyses of laminated composite hollow springs show almost the same trends of results as the composite solid springs. But the discrepancies among the mode shapes and natural frequencies become smaller. This might be due to the deformation coupling of layers of the different lamination angles, as well as more layers with 〖η=0〗^o.
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Huang, Yi Shang, and 黃衣聖. "Comparisons of Curved and Straight Beam Finite Elements on Free Vibration Analysis of Rectangular Cross-Section Helical Springs made of Fiber-Reinforced Composite Materials." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/00385617958224759536.
Full textAbstract:
碩士國立中興大學
機械工程學系所
105
In this thesis the free vibration of rectangular cross-section helical springs is studied using two types of beam element. The first type element is the 3 node, 18 degree-of-freedom, curved beam element and the second, the 3 node, 23 degree-of-freedom, straight beam finite element. The springs are assumed to be made of isotropic materials or fiber-reinforced composite materials. In both elements, the axial and lateral displacement, as well as the deformation due to both shearing and twisting of beam are considered, while in straight beam element, additional flexural deformations of beam’s flexibility in its width direction and the warping of cross section are included. The curved beam element of rectangular cross section is adapted from Ref. [14] where springs of circular cross section are treated. The straight beam element are derived based on displacement field of Ref. [18] and by following the same procedure of obtaining the displacement transformation matrix considered by Ref. [4]. The circular cylindrical spring deformation is described in terms of Frenet-Serret local coordinates. The Hamilton’s principle together with finite element method is used to derive the element’s mass and stiffness matrices for both curved and straight beam elements. For the case of curved beam element matrices, they can be directly assembled to obtain the corresponding global mass and stiffness matrices. In contrast, the straight beam element matrices must be transformed first using the displacement transform matrix before being assembled to obtain the global ones. In the numerical examples, natural frequencies and mode shapes of isotropic helical springs of 3 turns and the width to thickness ratio b/h=1, 3, 5 are studied and compared with those of ANSYS for the free-free and fix-free boundary conditions. It is found that the present curved beam element performs well when b/h = 1 or close to one, while the straight beam element although doesn’t work well when b/h = 1, do obtain much better results than curved beam element comparing with those of ANSYS for the studied cases b/h = 3, 5. Also studied in the numerical examples are the effects of Poisson’s ratio, fiber angles of composite laminate.
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Nandhini, Devi N. "A Feasibility Map-Based Framework and Its Implementation for Selection in Engineering Design." Thesis, 2015. http://etd.iisc.ernet.in/2005/3770.
Full textAbstract:
A pragmatic method for selecting components and devices from a database or parameterized models is developed in this thesis. The quantitative framework presented here is sufficiently general to accommodate an entire device assembly, a component, or a sub-assembly. The details pertaining to a device or a component are classified into three sets of variables: (i) user-specifications, s (ii) device parameters, p , and (iii) device characteristics, c .
Functional, practical, and performance-related attributes that a user can provide comprise user-specifications. Since, most often, a specification cannot be specified as a single number, we allow the user to enter a range with lower and upper bounds. Device parameters comprise the geometry and material properties, and device characteristics include functional requirements and performance criteria. Thus, for a device, all its functional and utility attributes are contained in the union of sets s and c , whereas the geometry and the material properties are in set p . The
equations governing the physical behavior of the device are written in terms of s , p , and c . These equations may sometimes be readily available; when they are not, it may be necessary to formulate them as required.
By solving the governing equations along with the inequalities that arise from the lower and upper bounds on s , we obtain feasible ranges on p and c . Then, for any pair of device characteristics, a 2D feasible map is drawn, to visually portray the consequences of user-specifications. If the feasible map is null, small, or large, it indicates that the user-specifications are infeasible, stringent, or there is much scope for design, respectively. This can be inferred even before the designs are considered.
Juxtaposed on the feasible map are points or lozenges corresponding to the quantitative attributes of the entries in the database. The ones that lie inside the feasible map can be reckoned as meeting the user-specifications and thus, enabling selection. On the other hand, if there is no database or none of the devices in the database lie inside the feasible map, we can identify the feasible ranges of all the design parameters for every point inside the feasible map. This information is useful to the designer to redesign and arrive at feasible designs by using parameterized models of the device.
A Graphical User Interface (GUI) is developed to facilitate the user-interaction. The utility of the selection framework is demonstrated with a variety of case-studies including miniature pumps, heat pulse-based soil-moisture sensors, springs, flywheels, compliant mechanisms, micromechanical suspensions, etc. The latter two use kineto-elastic characteristics of deformable components. The framework, when used for materials selection, can be seen as an extension of Ashby’s materials selection method. This is also illustrated with two examples.