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Dissertations / Theses on the topic 'Compression spring'
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1
Ma, Huiyuan. "A web based compression spring design calculator /." Compression spring design calculator, 2001. http://wwweng.uwyo.edu/commend/Csdc.
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Song, Ju Ho. "Design, analyses and experimental study of a foil gas bearing with compression springs as a compliance support." [College Station, Tex. : Texas A&M University, 2006. http://hdl.handle.net/1969.1/ETD-TAMU-1825.
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Rueckert, Cheryl B. "Evaluation of preferential energy absorption in earlywood and latewood fibers of loblolly pine in cyclic compression." Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/5805.
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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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Мальцев, Олександр Сергійович, Александр Сергеевич Мальцев, Oleksandr Serhiiovych Mal'cev, Павло Васильович Кушніров, Павел Васильевич Кушниров, and Pavlo Vasylovych Kushnirov. "Усовершенствование вспомогательных опор станочных приспособлений." Thesis, Юго-Западный государственный ун-т, 2013. http://essuir.sumdu.edu.ua/handle/123456789/43105.
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Допоміжна підвідна опора містить корпус із опорним штирем, що опирається своїм скосом на похилу поверхню клина, стрижень з головкою, що вкручений в глухий нарізний отвір клина, і пружину стиску, що контактує з клином. Кнопка із ступінчастим отвором має можливість переміщатися співвісно зі стрижнем. Поворотна опора може змінювати кут свого нахилу.Вспомогательная подводимая опора содержит корпус с опорным штырем, который опирается своим скосом на наклонную поверхность клина, стержень с головкой, вкрученный в глухое резьбовое отверстие клина, и пружину сжатия, контактирующую с клином. Кнопка со ступенчатым отверстием имеет возможность перемещаться соосно со стержнем. Поворотная опора может изменять угол своего наклона.
An auxiliary underpinning support comprises a body with a support pin, which is based by its slant on an inclined surface of a wedge, a rod with a head is screwed into a blind threaded hole of the wedge, and a compression spring in contact with the wedge. Button with stepped bore can move axially with the rod. Rotary support can change its angle of inclination.
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Buchelt, Beate, Tobias Dietrich, and André Wagenführ. "Testing of set recovery of unmodified and furfurylated densified wood by means of water storage and alternating climate tests." De Gruyter, 2014. https://tud.qucosa.de/id/qucosa%3A38557.
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Densification is a well-known method for improving the mechanical properties of wood. In the present study, unmodified and furfurylated wood samples were densified and submitted to cyclic water storage tests and cyclic alternating climate tests. Swelling coefficients and spring-back data were determined for the evaluation of the quality of densification. The study shows that results depend on the test method applied. Simple water storage tests do not reflect the behavior of densified wood in the high humidity range. The spring-back data of unmodified samples are more influenced by the testing method than those of the furfurylated ones.
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Vít, Jakub. "Odstředivá brzda motoru pro pneumatikový válec." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-232084.
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The aim of my thesis is the design of centrifugal brakes to prevent twisting of the combustion engine with pneumatic compactor. In the first part of my thesis I deal with existing and similar systems that prevent over speeding. In the second part I deal with the design of its own centrifugal brake. This includes basic functional, strength, thermal calculation, design of components and fabrication drawings according to the assignment.
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Barber, Jabulani Randall Timothy. "Mechanical compression of coiled carbon nanotubes." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/28216.
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Thesis (M. S.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2009.Committee Chair: Lawrence Bottomley; Committee Member: Aldo Ferri; Committee Member: E. Kent Barefield; Committee Member: Levent Degertekin; Committee Member: Robert Whetten; Committee Member: Satish Kumar; Committee Member: Zhong Lin Wang.
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Limber, Björn, and Johannes Samuelsson. "Construction of a Micro Compressor for Maintenance Filling of Balancing Gas Springs - from Idea to Prototype." Thesis, Linköping University, Linköping University, Fluid and Mechanical Engineering Systems, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-16639.
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At the gas spring manufacturing company Strömsholmen AB there is the needfor a way to make the load alleviating gas springs more robust, endurable andmaintenance free. A small high pressure compressor with a control systemshould solve these problems. The system would have to raise the pressure in the gas spring if it were to drop under a level and let some pressure out if it were to increase over a certain level. The construction of this Micro Compressor system is presented in this master's thesis. At first, a deeper understanding of the task at hand was gathered resulting in a design specification, followed by a concept study generated by the systematic design method. The evaluation of the concept study resulted in a chosen concept for prototype production. This prototype system consists of a control system with a pressure switch, a pressure reducing valve and a Micro Compressor that raises the pressure when needed. An electric system was also designed to work with the pressure switch, actuating the compressor when needed. Thoughts of converting the Micro Compressor system to pneumatic drive were also considered to increase the scope of use. The prototype system was tested to see that the requirements in the design specification were met and then the project was handed back to Strömsholmen AB for future development together with a list of suggestions of things that need improvement.
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Owen, Michael Information Technology & Electrical Engineering Australian Defence Force Academy UNSW. "Temporal motion models for video mosaicing and synthesis." Awarded by:University of New South Wales - Australian Defence Force Academy, 2008. http://handle.unsw.edu.au/1959.4/39028.
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Video compression aims to reduce video file size without impacting visual quality. Existing algorithms mostly use transform coders to convert information from the spatial to frequency domain, and attenuate or remove high frequency components from the sequence. This enables the omission of a large proportion of high frequency information with no discernible visual impact. Sprite-based compression encodes large portions of a scene as a single object in the video sequence, recreating the object in subsequent frames by warping or morphing the sprite to mimic changes in subsequent frames. This thesis sought to improve several aspects of existing sprite based compression approaches, employing a temporal motion model using a low order polynomial to represent the motion of an object across multiple frames in a single model rather than a series of models. The main outcome is the demonstration that motion models used by sprite based video compression can be extended to a full three dimensional model, reducing the overall size of the model, and improving the quality of the sequence at low bit rates. A second outcome is the demonstration that super-resolution processing is not necessary if lanczos spatial interpolation is used instead of bilinear or bi-cubic interpolation, resulting in a savings in computational time and resources. A third outcome is the introduction of a new blending model used to generate image mosaics that improves the quality of the synthesised sequence when zoom is present in the sequence for a given bit-rate. A final outcome is demonstrating that performing superresolution processing and sub-sampling back to the original resolution prior to compression provides benefits in some circumstances.
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Arlegui, Leigh. "Changes in Anaerobic Sprint Performance, Perceived Muscle Soreness and Sleep Quality after Wearing Compression Garments during Recovery from a Strength Training Workout." Thesis, Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-31928.
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Background: Compression garments are elastic, body-tight pieces of clothing with different pressure gradients used as a recovery method after exercise, such as strength training. Compression garments have increased in popularity within recreational and elite athletes as it is believed that they promote a reduction of muscle soreness and inflammation, which in turn may enhance performance. However, the exact physiological, psychological and performance enhancing effects of compression garments after recovery still remain unknown. Aim: To investigate whether female and male recreational athletes wearing full leg customised compression garments for at least 15 hours following a personalised strength training workout leads to an improvement in anaerobic sprint cycling performance as well as a reduction of perceived muscle soreness. Additionally a sleep quality assessment was conducted to assess the effects of the garments during sleep. Methods: Thirteen male and female subjects took part of a cross-over, randomised, controlled study. Subjects performed the first set of tests including Wingate anaerobic sprint test followed by their personalised strength training workout, after which they recovered with Compression Garments (CGS) or without compression garments (CON). They then returned 24hrs later to perform the second set of tests. Ten days later the same procedure was conducted however the other recovery method was used. Results: No significantdifferences were found between CGS and CON for the Wingate anaerobic test performance. Perceived muscle soreness was lower when subjects wore the garments and they felt better recovered 24hrs post-intervention compared to the CON condition. Some aspects of sleep were affected by wearing the compression garments during sleep however it was unclear whether this had an impact on performance. Conclusion: Recovering with customised full leg compression garments did not promote an improvement of physiological power performance 24 hours after a personalised strength training workout session. However perceived muscle soreness was reduced and the perception of recovery improved. The compression garments caused some sleep disturbances as subjects rated that they were too warm, suggesting a possible drawback of recovering with garments if worn during sleep.
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Švrček, Jakub. "Třísítný vibrační třídič." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-416620.
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This diploma thesis deals with the design of an inclined three-sided vibrating screen, which is designed for sorting bulk aggregates. The aim of the diploma thesis is primarily to make a construction design with a specific comparison of various design solutions, considering the calculated operating parameters. In the construction design, is used not only the experience of the manufacturer of this type of machine, but also recommendations based on the manu-facturers of screens component. The design also includes a comparison of two types of flex-ible mounting, which is one of the basic structural units of the entire vibrating screen. The thesis is conceived from the basics, with emphasis on the simplicity and functionality of the device.
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田中, 剛., and Tsuyoshi Tanaka. "『High-Pressure Shock Compression of Solids V : Shock Chemistry with Applications to Meteorite Impacts』, Lee Davison, Yasuyuki Horie, and Toshimori Sekine (Eds.) Springer-Veriag New York, Inc., 248ページ, ISBN 0-387-95494-5." 日本惑星科学会, 2002. http://hdl.handle.net/2237/10886.
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Ye, Getian Information Technology & Electrical Engineering Australian Defence Force Academy UNSW. "Image registration and super-resolution mosaicing." Awarded by:University of New South Wales - Australian Defence Force Academy. School of Information Technology and Electrical Engineering, 2005. http://handle.unsw.edu.au/1959.4/38653.
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This thesis presents new approaches to image registration and super-resolution mosaicing as well as their applications. Firstly, a feature-based image registration method is proposed for a multisensor surveillance system that consists of an optical camera and an infrared camera. By integrating a non-rigid object tracking technique into this method, a novel approach to simultaneous object tracking and multisensor image registration is proposed. Based on the registration and fusion of multisensor information, automatic face detection is greatly improved. Secondly, some extensions of a gradient-based image registration method, called inverse compositional algorithm, are proposed. These extensions include cumulative multi-image registration and the incorporation of illumination change and lens distortion correction. They are incorporated into the framework of the original algorithm in a consistent manner and efficiency can still be achieved for multi-image registration with illumination and lens distortion correction. Thirdly, new super-resolution mosaicing algorithms are proposed for multiple uncompressed and compressed images. Considering the process of image formation, observation models are introduced to describe the relationship between the superresolution mosaic image and the uncompressed and compressed low-resolution images. To improve the performance of super-resolution mosaicing, a wavelet-based image interpolation technique and an approach to adaptive determination of the regularization parameter are presented. For compressed images, a spatial-domain algorithm and a transform-domain algorithm are proposed. All the proposed superresolution mosaicing algorithms are robust against outliers. They can produce superresolution mosaics and reconstructed super-resolution images with improved subjective quality. Finally, new techniques for super-resolution sprite generation and super-resolution sprite coding are proposed. Considering both short-term and long-term motion influences, an object-based image registration method is proposed for handling long image sequences. In order to remove the influence of outliers, a robust technique for super-resolution sprite generation is presented. This technique produces sprite images and reconstructed super-resolution images with high visual quality. Moreover, it provides better reconstructed low-resolution images compared with low-resolution sprite generation techniques. Due to the advantages of the super-resolution sprite, a super-resolution sprite coding technique is also proposed. It achieves high coding efficiency especially at a low bit-rate and produces both decoded low-resolution and super-resolution images with improved subjective quality. Throughout this work, the performance of all the proposed algorithms is evaluated using both synthetic and real image sequences.
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Li, Yung-yi, and 李勇圻. "The Compression and Fatigue Effect of Different Fibers of Braided Composite Sprial Spring." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/61947133942376055337.
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碩士逢甲大學
紡織工程所
94
In this thesis, composite springs were made of different fiber prepreg .ie carbon fibers, E-glass fibers and Kevlar 49 fibers, with relevant mechanical sprig constant (K) and fatigue tested after parts cured. According to the experimental results, the structure of composite springs mixed with carbon fibers and glass fibers have the higher load per unit compression displacement which is better than other composition. After comparing with other structures, the C50G50 structure of spiral spring has good properties with more cost effective. Its load per unit compression displacement reaches 469.3 lb/in and the displacement is 1.590 in. Fatigue resistance was tested by fixing compression displacement, which was set as 70 percent of maximum compression displacement of the composite spring with 300,00times a cycle. Based on the fatigue test, the decreases of load during fatigue test are both in the range of 5 percent for the springs made of carbon fibers and glass fibers (C50G50, C30G70) and the sprigs made of high modulus carbon fibers and glass fibers (HC50G50, HC30G70).
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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.
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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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Lee, Bo-Han, and 李柏翰. "Study and Implementation on the Automatic Characteristic Measurement of Oval-Shape Compression Spring." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/kbud97.
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碩士國立虎尾科技大學
動力機械工程系機械與機電工程碩士班
105
Compression springs are widely applied to the life and the industrial fields. In terms of long-distance and high-speed optical fibers, the compression springs provide contact force in the optical fiber connector and keep the connectors in stable contact. The spring will produce axial and lateral displacement, lateral displacement caused by the lateral force will make the connector within the contact force is uneven, thereby affecting the stability of optical fiber transmission. Therefore, how to reduce and detect the spring force when the lateral force is the most important things when design the compression spring. However, the spring testing equipment aim to spring constant on the market. Other testing equipment for lateral force all as shock or special for large compression spring. Therefore, our study build a small compression spring of testing equipment. We test automatically and eliminate the error by man-made. On the other hand, we take measured effects, test equipment and limited element to evident the accuracy of test equipment. Through the experiment of spring measurements, we find that at the same boundary conditions and compression distance, the change of spring long axis and its lateral force. The results show under certain conditions, most will cause the difference of spring lateral force 32.26%.
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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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Cheng, Ming-San, and 張明三. "A Study on the Stress Simulation and Design Parameters of Oval-shape Compression Spring." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/evqn23.
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碩士國立虎尾科技大學
動力機械工程系機械與機電工程碩士班
105
Compression springs is very common in industrial applications, with spring force as the main target of the spring design. For example, inside a 400G high-speed transmission communication connector (32-multi-fiber MPO connector), a compression spring is required to provide a stable contact force. In addition,the requirements of the vertical spring force, the side spring force will also influences of the optical fiber transmission is stable, especial light reflectivity. This paper main study the influence of different spring design parameters and boundary condition on the spring force of compression spring by simulation and experiment. Through the finite element analysis and spring force measurement test, the total reaction force of the lower end node of the spring is verified as the basis for the determination of the spring force. And further explore the different boundary conditions and design parameters set, the spring force changes. The results of the study found the most, under the specific parameters may cause the spring lateral force increased by 132% .
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(7847843), Rahul Deshmukh. "Influence of geometry and placement configuration on side forces in compression springs." Thesis, 2019.
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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.
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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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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.
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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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Chung, Yin-Kai, and 張殷愷. "Finite element analysis of design parameters for compression springs." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/47830987978550558019.
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碩士華梵大學
機電工程學系博碩專班
101
The aim of this paper is to study the design of the compression coil springs. The modification method of the spring constant estimated from the conventional spring design equation was proposed. The variation of the compression deformation during the spring coiling process was analyzed using the finite element software ANSYS. The experiments of spring compression were performed by the universal testing machine and the spring coiling was performed by the coiling machine. The experimental parameters of the spring coiling such as the wire diameter, coil diameter, position of the forming roller and the pitch bar were studied. The spring back and the pitch formation during the coiling process, and the compression deformation during the compression test were simulated using the ANSYS software. It can be found that the spring constant derived from the spring design equation, only considering the active coils, is obvious different from the ANSYS simulation results for the serious pitch variation in the seat coil. The present results proposed an effective modification method for the application of the conventional spring design equation. Keywords: Compression spring, Spring design, Spring constant, Finite element method.
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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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Chang, Hsien-Jen, and 張憲仁. "A Predicting Model Study of Compressive Strength with Recycled Building Materials Concrete Cured in Hot Spring Environment." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/beuhse.
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碩士國立高雄應用科技大學
土木工程與防災科技研究所
104
This study established a model to predict the compressive strength of the cement concrete after curing in the hot spring water in different areas with different substitution amounts (S) of the recycled building material of slag in substitution of the cement where Chang (2015) used the volumetric method to conduct the mix ratio design to mix the recycled building materials of slag, fly ash and waste LCD glass powder into the concrete and four kinds of representative hot spring water (Jhihpen, Chiaohsi, Sihjhongsi and Chohuo Natural Fire) in Taiwan to conduct curing in the hot spring environment at a constant temperature of 45 ℃. The compressive strength test was conducted, and the nonlinear multivariable regression analysis was performed based on the application of the hyperbolic model. According to the comparison of the compressive strength test results and the analysis values of the prediction model, the Mean Absolute Percentage Error (MAPE) of the slag concrete and slag and glass sand concrete in the hot spring water of Chiaohsi and Jhihpen obtained by way of regression is between 2.89%~3.94% and 3.07%~4.02% respectively, indicating the very good prediction results. The MAPE values after the curing in the hot spring water of Sihjhongsi and Chohuo Natural Fire are all greater than 20%, indicating very big errors. The cause of this phenomenon is possibly due to the affection by the magnesium ion reactions in the hot spring water during the 120-day curing of the slag concrete and slag and glass sand concrete, which result in the obvious reduction of the concrete compressive strength. It needs to be further studied and explored on whether the prediction model established in this study is applicable to other mix ratios or curing environments
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Heinrich, Nina. "FE-Modellierung von Elastomerkomponenten mit textilen Verstärkungscorden am Beispiel von Luftfedern." 2020. https://monarch.qucosa.de/id/qucosa%3A74913.
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Neben Reifen, Riemen und Schläuchen zählen speziell auch die Balgwände von Luftfedern zu den Kompositen, da deren weiche Elastomermatrix zur Verstärkung Gewebelagen aus textilen Corden enthält. Diese Verstärkungsträger bestehen aus miteinander verzwirnten Garnen, die ihrerseits einen Zwirn aus polymeren Filamenten darstellen. Luftfederbälge weisen dementsprechend eine hochkomplexe innere Geometrie auf und sind zudem durch stark anisotropes, nichtlineares Materialverhalten gekennzeichnet. Für die strukturmechanische Simulation von Luftfedern mit der Finite-Elemente-Methode (FEM) werden in der vorliegenden Arbeit neuartige, hochauflösende Modelle entwickelt, die diesen Eigenschaften Rechnung tragen.
Zunächst wird ein mathematisches Modell formuliert, das die verzwirnte Geometrie von Corden auf allgemeinen räumlichen Bahnkurven beschreibt und mithilfe dessen sich auch die lokale Orientierung der Filamente bestimmen lässt. Zur konstitutiven Modellierung des Filamentmaterials wird zudem ein transversal isotropes, hyperelastisches Materialmodell so modifiziert, dass bei Druckbelastung in Filamentrichtung nur noch die der Regularisierung dienende, isotrope Grundsteifigkeit zum Tragen kommt.
Das Geometriemodell der Corde ist die Basis für deren dreidimensionale Abbildung in FE-Netzen von Luftfederbälgen. Als erster Schwerpunkt wird ein auf zyklischer Symmetrie basierendes Streifenmodell entwickelt, das die Cordgeometrie im gesamten Balg vollständig auflöst. Ein besonderes Augenmerk gilt dabei der Generierung konformer Netze, um die Grenzflächen zwischen Matrix und Corden exakt darzustellen. Das Streifenmodell ermöglicht somit detaillierte Analysen zur lokalen Verteilung von Spannungen und Verzerrungen im Inneren der Balgwand. Als zweiter Schwerpunkt wird diese Art der Modellierung auf einen kleinen rechteckigen Ausschnitt der Balgwand übertragen. Dieser Teppich ist als Submodell konzipiert, das Verschiebungen für seine Schnittränder aus einem vereinfachten Globalmodell bezieht und demzufolge die Analyse allgemeiner, nicht axialsymmetrischer Lastfälle möglich macht. Abschließend werden die Modelle anhand einer Rollbalgluftfeder für Busanwendungen eingehend untersucht und einem Praxistest zum Vergleich zweier Konstruktionsvarianten unterzogen.Tires, belts, hoses and, in particular, air spring bellows are regarded as composites due to layers of reinforcing textile cords that are embedded in a soft elastomer matrix. These cords are produced by twisting yarns which, for their part, represent a twisted structure of polymeric filaments. Hence, air spring bellows feature a highly complex internal geometry as well as strongly anisotropic, nonlinear material behavior. For structural simulations of air springs by means of the finite element method (FEM), new high resolution models are developed here, which reflect all the aforementioned properties. At first, a mathematical model capable of representing the twisted geometry of cords on three-dimensional curves is introduced, which also allows to derive local filament orientations. For the constitutive description of filament material, a transversally isotropic, hyperelastic material model is modified so that only the small isotropic stiffness introduced for regularization remains in case of compressive loads in filament direction. The cord geometry model serves as the basis for their three-dimensional representation in FE meshes of air spring bellows. Firstly, the focus lies on developing a slice model relying on cyclic symmetry, which takes cord geometry into account throughout the entire bellows. Special emphasis is put on building conforming meshes in order to incorporate all material interfaces explicitly. As a result, the slice model allows for detailed analyses of local stress and strain distribution inside the bellows. Secondly, this type of modeling is applied to a rectangular section of the bellows. This carpet is conceived as a submodel acquiring the displacements to be imposed on its cut faces from a simplified global model, and therefore provides the opportunity to analyze general load cases not complying with axial symmetry. Based on a rolling lobe air spring used in bus applications, both models are examined thoroughly and, at last, subjected to a practical test comparing two different designs.
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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.