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1
Sarikaya, Onur Turgay. "Analysis Of Heat Treatment Effect On Springback In V-bending." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12610182/index.pdf.
Повний текст джерелаАнотація:
Aluminum based alloys have wide area of usage in automotive and defense industry and bending processes are frequently applied during production. One of the most important design criteria of bending processes is springback, which can be basically defined as elastic recovery of the part during unloading. To overcome this problem, heat treatment is generally applied to the workpiece material to refine tensile properties.
In this study, the effect of heat treatment on springback characteristics of aluminum studied both numerically by using finite element analysis and experimentally. For this purpose, two different materials are selected and various heat treatment procedures are considered. The aluminum sheets having thickness of 1.6 mm, 2 mm and 2.5 mm are bent to 60˚
, 90&
#730
and 120&
#730
. The von Mises stress distributions, plastic strain values and punch load values and comparison of the numerical and experimental results are also given.
2
Loth, Sebastian. "Atomic scale images of acceptors in III-V semiconductors band bending, tunneling paths and wave functions /." Göttingen : Univ.-Verl. Göttingen, 2008. http://d-nb.info/989995232/34.
Повний текст джерела
3
Loth, Sebastian [Verfasser]. "Atomic scale images of acceptors in III-V semiconductors : band bending, tunneling paths and wave functions / Sebastian Loth." Göttingen : Univ.-Verl. Göttingen, 2008. http://d-nb.info/989995232/34.
Повний текст джерела
4
Wasserbauer, Jaromír. "Lokální zkoušky mechanických vlastností materiálů." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2009. http://www.nusl.cz/ntk/nusl-216510.
Повний текст джерелаАнотація:
This thesis deals with measurement of hardness and microhardness in relation to structure of homogeneous and heterogeneous materials. In the introduction basic theoretical background is commented, i.e. definitions, terminology, principles of measuring techniques for estimation of hardness, microhardness, tensile strength, compressive strength and bending strength. Follows a brief review of present research results focused on use of described principles in materials engineering. Then the experimental equipment and sample preparation is described. The crucial part of the thesis is summary of achieved results of original measurement and discussion of their relations to each other. Finally, the groundbreaking estimation is described, showing the correlation of chemical composition gradient and mechanical properties in interfacial zone of geopolymeric material.
5
Myšičková, Lucie. "Vývoj a zkoušení vysokohodnotných betonů pro subtilní konstrukce." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2014. http://www.nusl.cz/ntk/nusl-226971.
Повний текст джерелаАнотація:
Thesis describes properties of HPC compared to concretes of normal and high strength. It further describes the input materials and the procedure for designing the composition of the mixture. It gives examples of already completed structures made of HPC. The experimental part describes the optimization of concrete mix and production of specimens. In the end results of testing the properties of the developed mixes from tests of dynamic and static modulus of elasticity, compressive strength and tensile strength by bending are described.
6
Gottwaldová, Aneta. "Studium vlastností cementových kompozitů s rozptýlenou výztuží z anorganických vláken." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2019. http://www.nusl.cz/ntk/nusl-392335.
Повний текст джерелаАнотація:
Diploma thesis deals with study of properties of cementious composites with fiber reinforcement from glass and basalt inorganic fibers. Diploma thesis includes a theoretical and experimental part. The theoretical part deals with information about glass and basalt fibers, their durability and usage. In the experimental part we monitored properfies of cement composites with basalt and glass fibers. Fibers were exposed to an aggressive environment. The properties of composites with reference fibers were compared with composites with fibers affacted by the aggressive environment. The properties of composites were examined after 28 and 90 days. We monitored compresive strenght, bending tensile strenght, tensile strenght, surface layer strenght and SEM.
7
Fójcik, Tomáš. "Vliv triaxiální deformace kameniva na vlastnosti betonu." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2009. http://www.nusl.cz/ntk/nusl-216555.
Повний текст джерелаАнотація:
This diploma work takes focus in elastic modulus of unbound granular aggregates, which was determined by repeat load triaxial test and in deformation behaviour of unbound granular aggregates - elastic and plastic deformation. It was examine the propriety of this aggregate for its service as underlying granular material in pavement. Further, there was observed the influence of elastic modulus of unbound granular aggregates on concrete characteristics - compressive and bending strength. Finally, it was observed the influence of individual fractions of aggregates on its elastic modulus and strength of concrete.
8
Vrtal, Roman. "Diagnostika poruch a vad podlah v bytové a občanské výstavbě." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2014. http://www.nusl.cz/ntk/nusl-227022.
Повний текст джерелаАнотація:
The object of the thesis is a description of preparation process, realization and subsequent treatment of floors based on calcium sulphate, including problems related to the issue. The aim of the work is to closely acquaint the reader with methods used in diagnostics of flooring failures and defects in the housing and civic construction, including practical applications of these methods on real structures. The work also includes experimental analysis of a real floor construction during local load effect.
9
Šafář, Martin. "Vliv povlakování na lomové chování ledeburitické oceli." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2010. http://www.nusl.cz/ntk/nusl-229293.
Повний текст джерелаАнотація:
This work deals with tool steel Vanadis 6. It describes the preparation of samples for the three-point bending test, with which it examines the influence of surface roughness, the effect of nitriding, coating and duplex coatings on fracture behaviour of the steel. First, it examines bending strength and the total energy required to work of fracture. The work also includes mapping and measurement of surface roughness on different layers. This measurement is performed on a confocal microscope.
10
Dvořák, Richard. "Studium efektu aplikace celulózových vláken v cementových kompozitech." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2016. http://www.nusl.cz/ntk/nusl-240420.
Повний текст джерелаАнотація:
This diploma thesis is focused on composition and processing of cellulose fibers and their usage in cementitious composites. It describes key attributes of cellulose fibers, which has to be acquired for effective use in cement composites. There are stated effects of cellulose fibers on concrete properties, such as workability, physical and mechanic attributes and freeze-thaw resistance. In experimental part is designed a mixture with portion of cellulose fibers. There has been performed various tests to define the effect of cellulose fibers. There was designed experiment to determine its alkali resistance for fibers itself, and possible changes in microstructure of fibers were analyzed by optic and electron scanning microscope.
11
Grebeň, Petr. "Výpočet průhybu součástí při obrábění." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2008. http://www.nusl.cz/ntk/nusl-228344.
Повний текст джерелаАнотація:
Selected chapters of the science branch "Elasticity and strength" applied to manufacturing of thin parts with various solution approaches. Applying theory of bars and a non-linear differential equation for the deflection line of the second order to a machined shaft. Numerical calculation in the ANSYS program. Evaluation and design of solution variants to machine thin shaft parts without supporting them.
12
Hlaváček, Jaroslav. "Příměsi ovlivňující tuhnutí portlandského cementu." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2012. http://www.nusl.cz/ntk/nusl-216898.
Повний текст джерелаАнотація:
During the production of concrete is important the careful selection of raw materials. Nowadays, we are trying in the production to minimize the economic burden and to maximize the use of secondary raw materials. This work is focused on the use of secondary raw materials from the energy industry in construction for the preparation of hydraulic binders. As the main raw materials were used different power plant fly ash from fluidized combustion. The composition of these secondary materials is quite different from conventional high-temperature ash, due to mixing with water they solidify and harden. Experiments were performed with three lodge fly ash from electrostatic precipitators of the fluidized combustion and one high-temperature fly ash. This work is focused on the possibility of monitoring the use of these secondary materials in construction, especially when tests were evaluated characteristics of strength and speed of setting and hardening.
13
Panenková, Monika. "Reaktivní práškové kompozity a cementové kompozity bez makropórů." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-372126.
Повний текст джерелаАнотація:
This diploma thesis deals with the design principles and manifacture of ultra performance concrete (UHPC), reactive powder composites (RPC) and other fine-grained materials, such as Macro defect free (MDF) or Densified systems with small particles (DSP). Theoretical part of this work is focused on the requirements of properties and composition UHPC and RPC and methodology of their design principles. Experimental part describes design principles RPC, manufacture of test specimens, testing of certain physical and mechanical properties, such as tensile strenght, bending strenght and compressive strenght and determination chemical character X-ray and thermal analysis.
14
Březina, Matěj. "Příprava a charakterizace porézních materiálů na bázi hořčíku." Doctoral thesis, Vysoké učení technické v Brně. Fakulta chemická, 2018. http://www.nusl.cz/ntk/nusl-390297.
Повний текст джерелаАнотація:
Bulk magnesium materials produced nowadays via powder metallurgy are based on a vastly extensive technological spectrum, which makes it possible to create a wide range of materials. This work focuses on the preparation of bulk materials from magnesium powder by cold pressing and hot pressing, sintering and field assisted sintering. The bulk materials were prepared in a series of compacting pressures from 100 MPa to 500 MPa and the sintering temperatures were selected in the range of 300 ° C to 600 ° C in order to characterize the influence of the manufacturing conditions and technology on the final properties of bulk materials. Prepared materials were evaluated in terms of microstructure, hardness, microhardness, three-point bend test, and fractography. From the hot pressed materials, the samples prepared at 400 and 500 MPa and 400 °C had the highest strength and hardness. The classic sintering of magnesium in the furnace with argon atmosphere proved to be ineffective due to the oxide layer on the surface and the presence of oxygen in technical argon. The SPS sintering (Spark Plasma Sintering) was the more effective with the lower applying pressure used to make the preforms and with the higher applied pressure during the SPS process itself. Highest strength and hardness were achieved in this case of materials sintered at 600 ° C prepared from free powder and the most porous preform (100 MPa). The bulk materials were prepared using all methods used, but the properties of these materials varied considerably depending on the technology used.
15
Plochý, Ondřej. "Vývoj sklobetonů s vysokými mechanickými vlastnostmi." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-371943.
Повний текст джерелаАнотація:
This master thesis summarizes the current knowledge regarding the design and properties of glass fiber reinforced concrete products. It also deals with the design of a new concrete recipe for Dako spol. s.r.o company. There is verified effect of changes in input materials in real conditions the company to increase tensile bending strength above 20 MPa.In particular, verification of the use of building chemistry like superplasticizing additives, polymer-cement matrix or a change type or dose of glass fiber.
16
Coufalík, Pavel. "Návrh a posouzení směsi pro asfaltové vrstvy se zvýšenou odolností proti šíření trhlin (SAL)." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2013. http://www.nusl.cz/ntk/nusl-226447.
Повний текст джерелаАнотація:
This master's thesis deals with the possibility of special asphalt-rubber mixture using - Stress Absorbing Layer (SAL). In the theoretical part the SAL and test methods are described. In the practical part, several different mixtures are designed and selected mixtures were tested. Low-temperature characteristics, permanent deformations, bending tensile relaxation, stiffness modulus and fatigue properties were determined. Based on the test results the mixtures were compared and their benefit is evaluated according to Performance Pavement Design Method, the pavement structure was evaluated by using of computer programme LayEps.
17
Piterka, Miloslav. "Studium deformace kruhových otvorů v závislosti na jejich odstupu od ohybu při dvoubodovém ohýbání na ohraňovacím lisu." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018. http://www.nusl.cz/ntk/nusl-382123.
Повний текст джерелаАнотація:
The thesis is focused on studying deformation of the circular holes in the limit bending space, depending on the material type, distance from bend, the thickness of material and diameter of hole. After analyzing all necessary technological parameters was bending technology on press brake selected. An experiment for which the tools and press brake Trumpf TruBend 5170 were selected was designed and performed. Samples for the study were designed, bent and measured. The charts have been prepared for practical use in the company from measuring. In addition, simulations were processed in Ansys program and graphs were compiled to compare the main effect of the hole deformations. Two methods were chosen to prevent deformation in limit bending space. Under-cutting method by laser and method of using special Rollbend tool. In the end, economic studies for the Rollbend tool were developed instead of under-cutting hole with grinding.
18
Havlíková, Ivana. "Vyhodnocení lomových testů těles z vybraných stavebních materiálů pomocí modelu Dvojí-K." Doctoral thesis, Vysoké učení technické v Brně. Fakulta stavební, 2016. http://www.nusl.cz/ntk/nusl-355611.
Повний текст джерелаАнотація:
The purpose of dissertation is the analysis of the calculation of fracture parameters using Double-K fracture model for quasi-brittle specimens with the stress concentrator loaded by three-point bending or wedge splitting. To calculation of these parameters was used the developed DKFM_BUT software in Microsoft Excel application with using of Visual Basic programming language. Furthermore, the adequate shape functions and compliance functions were introduced for the selected wedge splitting test configurations. Main part of this dissertation is the series of comprehensively implemented and evaluated fracture experiments on specimens from advanced building materials, while the attention was paid to the analysis of experimental data. Finally, the selected results obtained using mentioned software support were presented and discussed.
19
Viszlay, Viliam. "Ohýbaná tělesa: Numerická podpora v software ANSYS." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2016. http://www.nusl.cz/ntk/nusl-240183.
Повний текст джерелаАнотація:
The aim of the thesis is the investigation of fracture-mechanics parameters on specimens made of quasi-brittle materials. The principles of two-parameter fracture mechanics are used. Couple of numerical simulations were done and their outputs are used for two main analysed specimen geometries. For simulations the finite element method software ANSYS is used. In the first part, the thesis focuses on bended specimens. The influence of different geometric parameters on fracture mechanics behaviour of cracked specimen is investigated. For model calibration the outputs of other authors are used. In the second part the specimens for modified compact-tension test (CT test) are analysed. Similar to the first part, the influence of geometric parameters of the specimen (in this case, the specimen size) on fracture mechanics parameters were investigated. The modified CT test was derived from CT test which is commonly used for metal materials testing as the suitable geometry for cement-based composite materials testing. The outputs of both parts are calibration polynomials, which are expressions obtained for different specimen geometries, giving the value of fracture mechanics parameter as the function of specimen geometry. As the example, calibration curves are used to obtain fracture toughness of tested material using the outputs from recent experiment.
20
Lidmila, Ladislav. "Rekonstrukce mostu v Ledči nad Sázavou." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2020. http://www.nusl.cz/ntk/nusl-409797.
Повний текст джерелаАнотація:
Diploma thesis deals with reconstruction of old beam bridge in town Ledeč nad Sázavou. Three variants of reconsttruction were done. Detailed structural design report was done to one of them, streithening with post-tensioning. Calculation of load effect was solved with finite elemet method via software on grillage model. Construction was checked on ultimate limit state and serviceability limit state. Necessary drawings were elaborated to chosen method.
21
Kulich, Pavel. "Dynamická analýza koleje." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-265372.
Повний текст джерелаАнотація:
The diploma thesis deals with analytical description of vehicle - track dynamic interface. There are described basic analytical models which are subsequently extended in order to get a more precise description of dynamic phenomena. The aim is to compile a model that faithfully describes the dynamic phenomena in the track. These new compiled models are qualitatively compared with data obtained by measuring in the track.
22
Kukla, Radim. "Statické řešení dostavby nemocnice v Písku." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-265241.
Повний текст джерелаАнотація:
In this diploma thesis „Static solution of hospital completion in Pisek“ I study statical solution of one new building of hospital. Statical solution includes the design and dimensioning of reinforced concrete floor structures and peripheral beams. The floor structure consists of point supported reinforced concrete slab. The floor slab is supported by columns and walls. The aim of the project is to desing and evaluate the ultimate limit state of reinforced concrete slab and beams. Also was created 3D computational model to analysis the construction, model was created in software Scia Engineer. To verify the resulting values of internal forces was used to the method of replacement frames. The thesis includes an analysis of internal forces in the structure, while based on different types of soil. Individual values are compared. Finally was made drawings of solved part of the building.
23
Vyhlídal, Michal. "Porušování vybraných stavebních kompozitů v blízkosti rozhraní plniva a matrice." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-372021.
Повний текст джерелаАнотація:
The interface between aggregate grains and matrix in cementitious composites is their weakest element. The topic is particularly significant in the case of high performance and high strength concrete technology for which the eliminination or reduction of these weak links are necessary. The aim of this thesis is to determine the influence of the interface on the fracture behaviour of the cementitious composites. The fracture experiments were performed for this purpose and were complemented by the nanoindentation’s results and scanning electron microscopy results. Numerical model was created in ANSYS software on the basis of these data and the fracture toughness values of the interface were evaluated by means of the generalized fracture mechanics principles. Conclusion of the thesis is proof that the interface properties have a significant influence on the fracture behaviour of cementitious composites.
24
Hájek, Jan. "Projekt podzemních garáží v Brně." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2012. http://www.nusl.cz/ntk/nusl-225505.
Повний текст джерелаАнотація:
The goal of the project is behaviour and dimensioning of selected monolithic concrete structure elements. Design and assessment of the building foundation was made. Slabs of the floors are dimensioned in detail. All computations are made in accordance with Eurocode 2. Drawing documentation is part of this project.
25
Bejček, Michal. "Vyhodnocení lomově-mechanických parametrů betonu po vystavení vysokým teplotám." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-371838.
Повний текст джерелаАнотація:
The diploma thesis is focused on the evaluation of mechanical fracture parameters of concrete after exposure to high temperatures. In the introductory theoretical part general principles of fracture mechanics with the concentration on a linear elastic fracture mechanics and non-linear fracture models for the concrete are summarized. The meaning of the three-point bending fracture test used for determination of fracture parameters is also explained. Further the influence of high temperatures on the partial components of concrete and general modeling of temperature loading is described. The practical part is concerned with the evaluation of fire experiments on the concrete panels including numerical simulations using GiD and ATENA software. The evaluation of data obtained from the three-point bending test carried out on specimens with initial stress concentrator taken from concrete panels is a main part of the diploma thesis. The values of modulus of elasticity, effective fracture toughness, work of fracture and fracture energy are determined from the measured F–d and F–CMOD diagrams after their proper corrections in the GTDiPS application. The evaluation of the selected mechanical fracture parameters was performed by StiCrack software using effective crack model and work of fracture method and DKFM_BUT software using the double-K fracture model. Finally, the attention is paid to the analysis of the obtained data.
26
Vlk, Radomír. "Návrh asfaltových směsí typu SAL určených pro opravu cementobetonových krytů." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-227301.
Повний текст джерелаАнотація:
This master's thesis describes how to use the asphalt layer called Stress Absorbing Layer (SAL) and comparises it with other types of SAL with different types of asphalt binders. In the first theoretical part is SAL generally described. In the second part is SAL practically tested and described.
27
Benjamin, Anne Laura. "Scanning Tunneling Microscopy Studies of Defects in Semiconductors: Inter-Defect and Host Interactions of Zn, Er, Mn, V, and Co Single-Atom Defects in GaAs(110)." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu15254254578788.
Повний текст джерела
28
Mojžíšek, Dominik. "Dynamická analýza koleje." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-372123.
Повний текст джерелаАнотація:
The diploma thesis deals with descriptions of vehicle - track dynamic interface. There are described basic analytical models of railway track. The numerical models are created by using finite element methods with moving load simulated axle of rail vehicle. The aim of thesis is to create the model which most accurately describes the dynamic phenomena in the track. The results from models are compared with data obtained by measuring in the track. Next aim of thesis is to determine dependency of rail cross-sectional characteristics on equivalent rail head wear and then on rail deflection.
29
Matušíková, Anna. "Navrhování konstrukcí s FRP výztuží." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2012. http://www.nusl.cz/ntk/nusl-225478.
Повний текст джерелаАнотація:
This diploma thesis presents available FRP software for calculating load bearing capacity of the structures reinforced with FRP and compares them between each other. Furthermore theory and algorithm of my own software is presented here. Load bearing capacity of structures which are reinforced with non-metallic reinforcement and loaded by combination of normal force and bending moment can be solved by my programme. Effects of high temperatures on the concrete structures can be included in the calculation. In the second part of the thesis is calculated load-bearing capacity and deflection of the real beam reinforced with FRP reinforcement and load-bearing capacity of member with FRP reinforcement with effect of elevated temperature. This has been done using my software. Comparison of results from hand calculation and laboratory load-bearing testing is done at the end. This laboratory testing was accomplished by Institute of Concrete and Mansory Structures at our faculty.
30
Král, Petr. "Verifikace nelineárních materiálových modelů betonu." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-227601.
Повний текст джерелаАнотація:
Diploma thesis is focused on the description of the parameters of nonlinear material models of concrete, which are implemented in a computational system LS-DYNA, interacting with performance of nonlinear test calculations in system LS-DYNA on selected problems, which are formed mainly by simulations of tests of mechanical and physical properties of concrete in uniaxial compressive and tensile on cylinders with applying different boundary conditions and by simulation of bending slab, with subsequent comparison of some results of test calculations with results of the experiment. The thesis includes creation of appropriate geometric models of selected problems, meshing of these geometric models, description of parameters and application of nonlinear material models of concrete on selected problems, application of loads and boundary conditions on selected problems and performance of nonlinear calculations in a computational system LS-DYNA. Evaluation of results is made on the basis of stress-strain diagrams and load-displacement diagrams based on nonlinear calculations taking into account strain rate effects and on the basis of hysteresis curves based on nonlinear calculations in case of application of cyclic loading on selected problems. Verification of nonlinear material models of concrete is made on the basis of comparison of some results of test calculations with results obtained from the experiment.
31
Huang, Yuung Ming, and 黃永明. "Analysis of V-shape Bending Process Using Various Finite Element." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/69823322537968875153.
Повний текст джерелаАнотація:
碩士國立臺灣科技大學
工程技術研究所
81
The finite element scheme for the constant strain triangu- lar element，the four node and nine node quadrilateral element has been proposed in this paper to solve the condition of the plane strain of the V-shape sheet bending process．As for the analytic result of the constant strain triangular (3-CST) ele- ment and the full integration for the nine node quadrilateral (9-FI) element schemes will lead to the stress is high in the bend part of the forming process． and the full integration for the four node quadrilateral (4-FI) scheme to the finite element will lead to an over-constraining effect when the material is in the nearly incompressible elasto-plastic situation or the thickness of the sheet is very thin in the forming process．Me- anwhile，the reduced integration scheme will produce zero energy mode to the finite element model． @ According to the results and the phenomena numerical simu- ltation as above mentioned，the paper utilized the following modifies mentioned： The first one is the Hughes's Selective Reduced Integration (4-SRI) scheme， which the element stiffness matrix is composed by the reduced integration dilation matrix and full integration deviatoric matrix．And the other one is the Stablization Matrix (4-SM) scheme，which the element stiffness matrix is expressed by the sum of the reduced integration matrix and the Liu's stablization matrices．Also, the extended r-minimum r-minimum technique is adopted to deal with the elasto-plastic state and contact problems between the tool-metal interface．
32
Gautam, Vijay. "Investigations on springback in v-bending of tailor welded blanks." Thesis, 2016. http://localhost:8080/iit/handle/2074/7200.
Повний текст джерела
33
Chen, Tsung-Chia, and 陳聰嘉. "Study on V-Bending Process of Camber Behavior of Sheet Metal." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/22730108485442049755.
Повний текст джерелаАнотація:
博士國立臺灣科技大學
機械工程系
92
This study aims to clarify the process conditions of the V-die bending of a steel sheet metal. It provides a model that predicts not only the correct punch load for bending, but also the precise final shape of products after unloading, based on the tensile properties of the material and the geometry of the tools used. A methodology for formulating an elasto-plastic three-dimensional finite element model, which is based on Prandl-Reuss flow rule and Hill’s yield criterion respectively, associated with an updated Lagrangian formulation, is developed to simulate sheet metal forming process. The shape function derived from a four-node quadrilateral degenerated shell element is associated into the stiffness matrix to constitute the finite element model. An extended rmin algorithm is proposed to formulate the boundary condition, such as nodal penetration and separation, strain increment and rotation increment, and altered elasto-plastic state of material. A series of experiments were performed to validate the formulation in the theory, leading to the development of the computer codes. The predicted value of the punch load by the finite-element model agrees closely with the results of the experiments. The whole deformation history and the distribution of stress and strain during the forming process were obtained by carefully considering the moving boundary condition in the finite-element method. A special feature of this V-die bending process is the camber profile after unloading. The computer program successfully simulates this camber profile. According to the developed finite element code, the computer codes are first executed to evaluate the effects of the size of the blank (blank width (W), blank length (L) & blank thickness (t0)) on the V-die bending process. The simulation was primarily to analyze in detail the effects of the size of the blank on the height of the camber, the bend angle after unloading, the distribution of thickness along the bend axis and the punch load. Several simulations and experiments were performed with varying process variables. The sheet metal V-die bending process is simulated to evaluate the effects of tooling geometry on the V-die bending process. The effects of process variables, such as punch radius (Rp), die radius (Rd), tool width (Wd) and tool angle (At), on the final shape after springback or springforward, the height of the camber, the distribution of thickness along the bend axis and punch load are discussed in detail. Using the finite-element code, simulations were run to evaluate the effects of strain hardening exponent (n), friction coefficient ( ) and normal anisotropy (R) on the camber height, springback angle after unloading and the distribution of thickness along the bend axis. The simulation clearly demonstrates the efficiency of the code to simulate various bending processes that proceed under complicated deformation and contact history. This work has provided an improved understanding of the sheet bending process for improving the manufacturing processes and the design of tools.
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Kim, Suenne. "I-V transport measurements of a single unsupported MWCNT under various bending deformations." 2008. http://hdl.handle.net/2152/9706.
Повний текст джерелаАнотація:
The first part of this dissertation is an introduction describing a brief historical background of carbon nanotubes (CNTs) and their pseudo 1D structure responsible for many exotic electronic properties. The second part describes our experimental setup. The third part is about the growing of Multi-Walled Carbon Nanotubes (MWCNTs) by the chemical vapor deposition (CVD) method. Then the fourth part demonstrates a simple but reliable method to make firm contact junctions between MWCNTs and metals such as tungsten (W). The novel point of our method consists, after making a mechanical preliminary contact at a selected MWCNT, in applying a series of voltage pulses across the contact. Thin oxide layers that may form between the MWCNT and the W wire, are removed in steps by the resistive heating and electron impact during the application of each voltage pulse. Furthermore, this simple process of contact welding in steps does not bring about any permanent change in the electronic transport properties of the MWCNTs. The fifth part discusses our bending experiments. We apply a uniform and continuous bending to a selected MWCNT at room and liquid nitrogen temperatures to study the strain effect on the electrical transport in the MWCNT. There are a few published experimental works related to the bending deformation; however, this is the first study of electronic transport properties in continuous bending and releasing deformations. We observed a saturation behavior with the MWCNT and also found the bending deformation causing an anomalous change in the saturation behavior. In the sixth part we depict some interesting phenomena due to the stretching deformation of MWCNT, where we were able to propose a simple model for electron localization induced by the deformation. The last part deals with the formation of the "X-junction" between two MWCNTs. A strong X-junction can be formed simply by means of the e-beam inside the Scanning Electron Microscope (SEM). The X-junctions may form the basic elements of nano-electronic circuits such as various metal-insulator junctions, quantum dots, and similar devices.text
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HSI, SUNG CHIANG, and 宋清溪. "The effect of opening size on the camber of V-shaped bending process." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/50680179041330832461.
Повний текст джерелаАнотація:
碩士國立勤益科技大學
機械工程系
103
This paper aims to investigate the effect of opening size for the camber of V-die bending of a sheet metal of steel and the effect of the V-die bending forming process according to different hole size (diameter 4,6,8,10mm) aiming at the hot rolled mild steel plate (SPHC) material. Through the simulation analysis of material parameter obtained from the tensile test to understand the camber height differences when forming different dimension of the opening in a V-die finite element program. This article is a combination of finite element method and finite element deformation theory (Updated Lagrangian Formulatiom, ULF) ideas, references Dynaform finite element analysis program and LS-DYNA solver, simulation V-bending process. This paper focuses on simulation and analysis by V-die bending deformation biographical information of all the stress and strain distribution process, the thickness distribution of the maximum height of the saddle shaped, and divided into two groups of sheet metal opening number, use mild steel hot-rolled steel (SPHC) plate that V-die bending test, and the finite element analysis results for comparison to verify the reliability of the analysis program. Via finite element analysis and experimental results that when the opening size of the saddle height diameter 4mm saddle height maximum, when opening size increases gradually resumed, the forming of the sequence gradually reduced until opening size of 10mm diameter when the saddle shaped height to a minimum. The proposed method of this paper can simulate the height of the V-die bending saddle of the manufacturing process effectively. Therefore, it can be widely used in a variety of V-die bending process, the establishment of a more comprehensive analysis of the data, in order to increase the finished workpiece after bending the sheet dimensions accuracy.
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Hung, Yi Hsiang, and 洪逸翔. "A Study On The Micro-Forming Of V-Bending Process Of Metallic Thin Sheet." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/33372087506532719149.
Повний текст джерелаАнотація:
碩士北臺灣科學技術學院
機電整合研究所
99
The capability of predicting the sheet metal part final geometry as well as springback amount is an important feature in the sheet metal bending processes. The occurrence of grain size effect make the application of a traditional process design methodology difficult. Therefore, the design of micro-forming operations is still largely performed through empirical techniques. While the design work is made by way of tools and processes, for effectively compensating and eliminating the springback, to understand the influence of grain size effects on springback is an important and powerful way. In this paper, the heat treatment was carried out for 99.5% Ferrum specimens at different temperature to obtain the objective grain size. A V-bending process was conducted for investigating the different objects. One of the objects is to discuss the springback considering the geometric size effect based on the same grain size while the specimens were bent with different thickness. In another object, discussion of grain size effect with springback measurement based on a same thickness situation is expressed. In the third object, the illustrations of experimental results are detailed with the punch radius and springback in sheet metal bending processes. The expression of the fourth object is detailed with the effect of punching speed during the V-bending process. Furthermore, this paper adopted the finite element method with the macro deformation module of DEFORM-3D software code to simulating the V-bending process.
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Shie, Rie Fong, and 徐日豐. "Endochronic simulation of V iscoplastic,Creep and relaxation for Thin-Walled Tube under Pure Bending." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/98355314002784312879.
Повний текст джерела
38
Hsu, Hau-Chi, and 徐豪志. "Study on Shape Memory Effect in Thermomechanical V-Bending of Ni-Ti Shape Memory Alloy Wire." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/17659432966834692149.
Повний текст джерелаАнотація:
碩士國立中興大學
機械工程學系所
101
The aim of this study is that shape memory treatment and V-bending process for nickel-titanium alloy wire are able to be accomplished within one thermomechanical process at high temperature. This method could provide an alternative choice for the nickel-titanium shape memory alloy wire to reduce the spring-back in V-bending process due to the creep effect. In this study, the influences of forming temperatures and process time on spring-back were studied. Furthermore, experiment was carried out to verify with the finite element analysis results. The material model used in finite element analysis was based on the mechanical properties of nickel-titanium alloy obtained by material testing. The results showed that the reduction of spring-back was more obviously when the forming temperature was increased. Spring-back could also reduce when the process time was long which resulted in stress relaxation due to the creep effect. In addition, to understand the effects of forming temperatures and process time on the phase transformation temperature, its measurement was executed by the DSC equipment. The testing of shape recovery rate of nickel-titanium alloy was conducted and the rate was more than 99%. Accordingly, the results of this study could offer a reference for the industry to improve the spring-back of V-bending process.
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Chiu, Chun-chin, and 邱俊欽. "Experimental design and performance analysis of the V-die bending process using the Response Surface Methodology." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/75995066716128875683.
Повний текст джерелаАнотація:
碩士修平技術學院
精密機械與製造科技研究所
98
In this study, an effective procedure of response surface methodology (RSM) was utilized for experimental design and performance analysis of the V-die bending process. The punch radius, die width, die corner radius and blank thickness were selected as effective processing parameters to investigate the influences on the performance of spring-back angle and thickness variation in the bending process. A standard RSM design called the centered composite rotatable design (CCRD) was applied in this experimental plan. Based on the analysis of variance and verification experiments, the quadratic models proposed in this paper were adequate to explain and analysis the effects of processing parameters, and can be utilized to predict the experimental value within the 95% accurate interval. The optimal conditions were also determined using the proposed quadratic model and the sequential approximation optimization method (SAO). Results show that the significant factors on the bending performance evaluations are the die corner radius, die width and blank thickness, which are noticeable variable factors as the resources of increasing quality. The experimental results using the optimal setting were easily clarified that the effective procedure proposed in this study greatly improved the desired target of performance analysis in the V-die bending process.
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KUMAR, SHARMA PANKAJ. "EXPERIMENTAL AND NUMERICAL STUDIES ON SPRINGBACK OF 2-PLY AND 3-PLY LAMINATE COMPOSITES OF ALUMINIUM AND STAINLESS STEEL." Thesis, 2023. http://dspace.dtu.ac.in:8080/jspui/handle/repository/20390.
Повний текст джерелаАнотація:
To meet the requirement of materials having higher tensile strength to weight ratio
along with corrosion resistance, the 2-ply and 3-ply clad sheets of aluminium and
stainless steel are being utilized in domestic applications, manufacturing of automotive
sheet metal parts, shipbuilding, and other industries. Metal clad sheet composites are a
different kind of composite material where alternating metal layers are bonded together
with inter-metallic bond.
The sheet metal components manufactured by forming processes may undergo some
geometrical changes due to the phenomenon of springback. The behaviour of
springback during bending of 2-ply and 3-ply clad sheet metals is very complex due to
the combination of sheets of different mechanical properties and thicknesses.
Accurate prediction of springback in clad sheets in a bending operation will help in
improving the die design by involving springback compensation. It would facilitate the
optimum selection of materials, blank design, and other design variables so as to
manufacture parts with minimum springback. In the present work, an analytical method
has been developed that predicts the amount of springback in bending of clad sheet
using input parameters from stress-strain diagrams of sheet materials like tensile
properties, strain hardening exponent and anisotropy of parent sheets. The total bending
moment in the analytical model at a cross sectional plane is calculated from the bending
stresses for different layers. Springback is calculated by superimposing the effect of a
negative bending moment of the same magnitude so as to simulate the unloading
phenomenon. Numerical simulations have also been done for the simulation of V bending of clad sheet using Abaqus software based on FEM (finite element method).
Experimental work has also been carried out and compared with the simulation and
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analytical results. The data from stress-strain plots for the parent and clad sheets was
generated using computerized UTM. The parent and clad sheets are characterized using
tensile properties, strain hardening exponent and anisotropy. The typical yield strengths
(0.2% offset) of clad sheets for the tensile specimens oriented at 0°, 45° and 90° are
observed to be 115MPa, 117MPa and 114MPa for a 2-ply and 153.5MPa, 174MPa and
176 MPa for a 3-ply sheet, respectively. A set of three punch profile radii was used to
conduct V-bending experiments for the measurement of springback on a computerized
UTM. The results from the analytical model and FEM simulation are seen found to be
in close agreement with the experimental results. It is observed that an increase in punch
profile radius causes a significant increase in springback for both 2-ply and 3-ply clad
sheets. For a 2-ply clad sheet, the bend samples (with AA1050 as inner layer ) which
are oriented at 45° to the rolling direction, the experimental values of springback, higher
than the other two orientations, are observed to be 4.12 and 4.88 with punch profile
radii of 15mm and 20mm, respectively. In case of a 3-ply clad sheet, the bend samples
(with SS304 as inner layer) oriented at 90° to the rolling direction, the experimental
values of springback higher than the other two orientations, are found to be 5.15° and
6.10° with punch radii of 15mm and 20mm, respectively. Similar trend of results is
obtained with analytical and simulation techniques. FE simulation results are closer to
the values of experimental results than the analytical model results. The analytical
model assumes a plane strain condition and neglects the neutral axis shift. These
assumptions are not made for the simulation. Also, a more robust material model is
used in FE simulations.
The effect of sheet setting on the die is also investigated in this work. Effect of the
position of aluminium sheet at both inner and outer layers is studied. Sheet setting
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conditions affect the values of springback due to the tensile strength variations and
different bending radii during V-bending operations. For both the sheet settings, the
residual stresses as predicted Abaqus simulations are in good agreement with the
experimental results except for a few cases.
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Loth, Sebastian [Verfasser]. "Atomic scale images of acceptors in III-V semiconductors : band bending, tunneling paths and wave functions / vorgelegt von Sebastian Loth." 2007. http://d-nb.info/996181148/34.
Повний текст джерела