Dissertations / Theses on the topic 'T-Joint'
To see the other types of publications on this topic, follow the link: T-Joint.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'T-Joint.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Zhang, Cheng. "Robotic 3D friction stir welding : T-butt joint." Thesis, Högskolan Väst, Avd för automationssystem, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-8250.
Full textAbstract:
This Master Thesis was performed in terms of robotic three dimensional friction stir welding with T-butt joint. Friction stir welding (FSW) is a solid state welding method that achieves the weld temperature by friction of a rotating non-consumable tool with the workpiece. Science and technology fast developing requires for higher seam quality and more complex welding joint geometry like 3D welds. In order to acquire high productivity, capacity and flexibility with acceptable cost, robotic FSW solution have been proposed. Instead of the standard FSW machine, using a robot to perform complicated welds such as, three-dimensional. In this report, a solution for weld a 3D T-butt joint, which located in an aluminium cylinder with 1.5 mm thickness using a robot, was developed. Moreover, two new paths were investigated in order to avoid the use of two welds to perform this type of joint. The paths were tested on 2D and on 3D (with a 5050 curvature radius) geometries. Both paths had good results. What is more, the parameter developing methods of FSW process, which is composed of necessary parameter setting, positional compensation was introduced. Specially,the study demonstrates how complicate geometry can be welded using a robot. Also,it shows that TWT temperature control is able to acquire high quality 3D welds. In addition, an analysis of the 2D welding and 3D welding was performed, which exposed that, keeping exactly the same welding conditions, higher lateral forces on the tool were found during 3D welding. Basis on the special case in this paper, when the tool goes like "climbing" the sample, the suffering force of tool decreasing with increasing the height(Z position); nevertheless, when the tool goes like "downhill", the suffering force of tool decreasing with decreasing the height (Z position). What is more, in 2D weld, increasing the downforce (Fz) results increasing the lateral forces which can be Fx and/or Fy. Finally, the future works suggestions were presented in terms of (1) performing the new paths into a real cylinder, (2) performing tensile test on the paths and comparing it with conventional path which weld twice, (3) researching how the downforce (Fz) influence the Fx and Fy during welding of different 3D geometries, (4) how the cooling rate of backing bar influence the seam quality when it is use the same welding parameters and (5) the effect of performing welds in the same welding temperature achieved with different combination of the tool rotational speed and downforce on the material properties
2
Al-Shukaili, Ahmed Khalifa Ali. "T-lymphocyte/monocyte interactions in relation to inflammatory joint diseases." Thesis, University of Bath, 2004. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.401286.
Full text
3
Eriksson, Berth. "Residual stress in a T-butt joint weld : cylinder versus plane plate geometry." Licentiate thesis, Luleå tekniska universitet, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-25665.
Full textAbstract:
The welding process introduces residual stress originating from the heating, melting and cooling of the material. From the point of view of fatigue and stress corrosion cracking, the weld residual stress perpendicular to the weld axis is of particular interest. When qualifying weld parameters for welds in large cylinders having a ratio of radius to plate thickness larger than say approximately 100; reference to plane plates are often made for the sake of simplicity. However, the weld residual stress perpendicular to the weld axis is severely underestimated in the plane plate compared with the cylindrical structure. This observation is especially pronounced in connection with preheating. The source of the differences is probably due to the radial constraint of the cylinder, compared with that of a plane plate. A plane test specimen will underestimate the weld residual stress perpendicular to the weld axis in a cylinder, even if the radius of the cylinder is very large. However, a test specimen for an 8 m diameter cylinder with a plate thickness of 35 mm needs only to have a segment width of approximately 1.3 m to reflect the stress in the real structure. The weld residual stress perpendicular to the weld axis in the vicinity of the weld toe is governed by the depositing of the weld bead adjacent to the weld toe, neglecting the accumulated strain from the previous deposited weld beads in the multi-pass joint weld. Introducing tensile straining perpendicular to the weld axis during the entire welding procedure reduces the weld-induced residual stress after completed welding. The plastic zone of the weld area will be subjected to compressive strain after completed welding, which in turn will reduce the weld residual stress. This can be achieved by cooling the weld area, which in this case is not recommended since the material is sensitive to hydrogen cracking, or by pre-stretching or modifying the locations for preheating, all aimed to impose a tensile axial straining around the weld area during the entire welding process.Godkänd; 2004; 20070131 (ysko)
4
Rickers, Michael A. "The effect of spring restraint on weld distortion in t-joint fillet welds." [Ames, Iowa : Iowa State University], 2009. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1468127.
Full text
5
Mann, Torsten. "Fatigue assessment methods for welded structures and their application to an aluminium T-joint." Doctoral thesis, Norwegian University of Science and Technology, Department of Engineering Design and Materials, 2006. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-1171.
Full textAbstract:
Following a short introduction, the state-of-the-art fatigue life assessment methods based on the nominal stress, the structural hot spot stress and the effective notch stress, as well as the crack propagation analysis are explained and discussed.
Thereafter, the effect of mean stress on crack propagation was investigated by exemplifying crack propagation data from different aluminium alloys. In this context, Walker's equation received wide attention. In addition, a new, simple equation to express the mean stress dependency of crack propagation data has been proposed.
In order to generate crack propagation data for the 6082-T6 aluminium alloy, investigate the behaviour of short cracks and find the mean stress dependency of crack growth in this alloy, crack propagation tests of sub-millimetre cracks subjected to different stress ratios have been carried out. The crack depth was successfully monitored on-line employing a special direct current potential drop technique. The crack propagation data generated verified the long crack propagation data given in Eurocode 9. In addition, useful experience was gained to improve future tests. Some evidence was found of accelerated crack growth near the threshold. Based on the data obtained and literature data a Walker exponent γ= 0.78 has been calculated for the aluminium alloy 6082-T6.
The fatigue life of welded aluminium T-joints has been estimated using the approaches introduced in Chapter 2. The results have been compared with experimental data from T-joints subjected to 4-point bending. In addition, a series of T-joints subjected to transverse bending has been fatigue tested and the results have been compared with predictions using the same fatigue life assessment methods.
The nominal stress gave a conservative prediction in case of the 4-point bending loading. Since no applicable detail category for the transverse bending load case exists, a suitable detail category has been suggested.
The structural hot spot stress approach resulted in conservative predictions (factor 4-10 in life) for both load cases.
The predictions from the effective notch stress approach are in excellent agreement with the experimental results, where the method using a 1 mm weld toe radius gave the best results. It has been shown that the method can be successfully applied to joints with wall thicknesses down to 3 mm.
The fatigue life predicted with the crack propagation approaches is in excellent agreement with the experimental results from the 4-point bending load when the Mk factor was used. Applying the local stress distribution, the predictions are conservative for both load cases.
The slopes of all predicted S-N curves, especially from the stress based methods, are steeper than the experimental curves.
6
Rolseth, Anton, and Anton Gustafsson. "Implementation of thermomechanical laser welding simulation : Predicting displacements of fusing A AISI304 T-JOINT." Thesis, Högskolan i Skövde, Institutionen för ingenjörsvetenskap, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-19946.
Full textAbstract:
Laser welding is an advanced joining technique with the capability to form deep, narrow, and precise welds. Numerical models are used to simulate the process in attempts of predicting distortions and stresses in the material. This is done to reduce physical testing, optimize processes and enable integrated product- and process development. The Virtual Manufacturing Process research group at University of Skövde wishes to increase their knowledge on modeling options of thermomechanical simulations to grant local industries these benefits. A numerical model for the laser welding process was developed in ABAQUS. This was done by examining the macrograph structure of a simple weld and applied to a stainless-steel T-joint welding application. The macrograph data was used to calibrate a mathematical heat source model. User subroutine DFLUX was used to enable movement of the heat source and element activation was used to simulate the fusion of the two parts. A T-joint welding experiment was carried out to measure deflection and the result was compared to numerical simulations. Different combinations of heat source models, coupling type and element activation was compared in relation to predicting the deflection. Computational time and modeling complexity for the techniques was also considered.The results showed that a 3D Gaussian heat source model will imitate the keyhole weld achieved superior to the compared 2D model. The 3D model provides greater flexibility since it enables combinations of any geometrical bodies. It was shown that element activation has a significant contribution on part stiffness and thus resulting distortions. To implement element activation a fully coupled analysis is required. The deflection of the fully coupled 3D simulation with element activation showed a 9% deviance in deflection compared with experiments.
7
Hajdaei, Amirhossein. "Extending the fatigue life of a T-joint in a composite wind turbine blade." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/extending-the-fatigue-life-of-a-tjoint-in-a-composite-wind-turbine-blade(f9fb5741-c97e-466b-84bc-53316cfbecf2).html.
Full textAbstract:
Wind turbines are classic examples of structures where their operating lifetime is controlled by the fatigue properties of the material. This is exacerbated by the 2D nature of the composite materials used in blade construction which are typically fabrics in a variety of formats (e.g. non crimp fabrics, uniweave, woven). The formation of internal detailed shapes within the blade, allowing features such as spars, shear webs and other connections, inevitably requires these 2D material configurations to be formed into 3D shapes. This introduces positions within the structure where load transfer occurs across regions with no fibre reinforcement. These weak areas become natural positions for the initiation of damage that can occur well before fatigue damage would be expected in the basic material subject to simple in-plane loading. The aim of this study is to modify and improve the blade structure in order to extend its working life and minimize geometry related fatigue issues. To achieve this goal T-sections have been manufactured as representative element of the blade's spar. T-sections have been made of carbon or glass fabric infused with epoxy resin using a vacuum-assisted resin-transfer moulding technique. The structure has been modified with different toughening techniques to increase its interlaminar fracture resistance (toughness) and hence delay or stop crack propagation. Methods such as the use of veil layers, tufting and 3D weaving techniques have been employed to improve the interlaminar fracture toughness of the T-joint. The changing parameters in samples are, the addition of the veil layer to the composite structure, veil material, tufting stitches and use of different 3D fibre weaving architectures in the fabrication of the composite T-joint. For T-joint testing, there was no standardised specimen shapes and no standard for specimen dimensions; as well as no test fixture designs or test procedures. Consequently, it was required to design a test rig and develop a test procedure for tensile and fatigue tests of T-joints. An additional investigation was performed to establish test specimen geometry suitable for testing in available Instron machines. Manufactured specimens were quasi-static and fatigue tested. Test results were compared and showed that 3D woven and polyester veil T-joints had the best performance among modified structures. However, it has been found that these structural modifications are performing differently in quasi-static and fatigue loading. The 3D woven four layer to layer inter wave sample that showed the best result in a quasi-static test was not the one with the best fatigue results but it was amongst the ones with the highest performance. SEM and optical microscopy were used to investigate fractured specimens in an attempt to establish the mechanisms involved in the fracture process of the T-joint. Finally, based on test and investigations results it has been concluded that the 3D weaving was the most effective modification to improve the static and fatigue properties of the T-joint. The T-joint modified with polyester veil showed the second best performance in both static and fatigue tests but the addition of the polyamide caused had negative effects on these properties.
8
Held, Sebastian [Verfasser], and T. [Akademischer Betreuer] Kohl. "Joint exploration of geothermal systems using geophysical and geochemical techniques / Sebastian Held ; Betreuer: T. Kohl." Karlsruhe : KIT-Bibliothek, 2018. http://d-nb.info/1164081195/34.
Full text
9
Kassab, Rabih Kamal. "Modélisation par la méthode des éléments finis des distorsion dues au soudage d'un joint en T." Mémoire, École de technologie supérieure, 2007. http://espace.etsmtl.ca/231/1/KASSAB_Rabih_Kamal.pdf.
Full textAbstract:
Dans ce memoire, il s'agit de la modelisation du soudage d'un joint en T par la methode
des elements finis.
Le but du modele est de prevoir les deformations et les contraintes residuelles associees
au soudage des plaques. Le modele peut s'adapter pour ameliorer le procede du soudage
en variant les parametres en jeu tels que la geometric du chanfrein, I'intensite du
courant, le depot simultane des deux cordons, la vitesse de la torche, etc.
L'experimentation est faite sur deux plaques de 3/8 pouce d'epaisseur (9.5 mm) et de
10 pouces de longueur (254 mm). La largeur de la premiere plaque est de 10 pouces
(254 mm) et celle de la deuxieme est de 6 pouces (152.4 mm), celle-ci est soudee
perpendiculairement au centre de la premiere. La deuxieme plaque est faite avec un
chanfrein de preparation de 'A pouce (6.35 mm) de hauteur et faisant un angle de
30 degres de chaque cote.
Pour avoir les parametres de soudage les plus precis possibles, le robot SCOMPI^ est
utilise pour la realisation des essais. Les parametres du soudage sont de 26,9 Volts,
220 Amperes et une vitesse d'avancement de 5 mm/seconde. L'efficacite du procede est
estimee a 77 %.
La simulation sert a predire numeriquement les temperatures, contraintes et
deformations lors du soudage. La demarche de la modelisation est divisee en deux
parties : la simulation thermique et la simulation structural.
La methode « birth and death » est utilisee pour la simulation du depot du metal
d'apport, et le modele du double ellipsoide propose par Goldak, Chakravati et Bibby est
utilise pour I'apport de la chaleur.
Durant la simulation du depot du metal d'apport, une relation entre I'incrementation du
temps et la taille des elements est faite. L'analyse transitoire est faite en fonction de la
position de la torche plutot qu'en fonction du temps.
Les resultats thermiques de la simulation se comparent bicn a ceux de I'experimentation.
Une difference maximale de 1,5 % a ete observee avec des temperatures comparables.
Ces temperatures sont obtenues de thermocouples colles sur la plaque horizontale (THi).
Les proprietes non lineaires du materiau en fonclion de la temperature sont utilisees.
Aussi, il y a une presentation d'une nouvelle fa^on pour le calcul du coefficient combine
(radiation-convection) de perte de chaleur en fonction de la temperature.
Les ecarts structuraux varient de 6.6 % pour la contrainte principale et jusqu'a 32.9 %
pour le deplacement du cote de la deuxieme passe. L'ccart sur les deplacements est
surtout lie a 1'incertitude de la rigidite du gabarit.
Le modele numerique reflete bien la realite. La facilite de varier ces parametres
geometriques. thermiques et structuraux le rend flexible pour simuler plusieurs soudages
de joints similaires.
Une amelioration du controle des conditions frontieres et d'autres de modeles de source
de chaleur sera utile pour des travaux futurs.
10
Kassab, Rabih Kamal. "Modélisation par la méthode des éléments finis des distorsion dues au soudage d'un joint en T /." Thèse, Montréal : École de technologie supérieure, 2007. http://proquest.umi.com/pqdweb?did=1459904971&sid=2&Fmt=2&clientId=46962&RQT=309&VName=PQD.
Full textAbstract:
Thèse (M. Ing.)--École de technologie supérieure, Montréal, 2007."Mémoire présenté à l'École de technologie supérieure comme exigence partielle à l'obtention de la maîtrise en génie mécanique". "par Kassab, Rabih Kamal" -- p. de. t. CaQMUQET CaQMUQET Bibliogr. : f. [141]-144. Également disponible en version électronique. CaQMUQET
11
Elfving, Filip. "Simulation of laser welding in sandwich rocket nozzle." Thesis, Karlstads universitet, Avdelningen för maskin- och materialteknik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-36830.
Full textAbstract:
This bachelor thesis has been carried out at GKN Aerospace. GKN is a member of European Space Agency, designing and manufacturing rocket-nozzles for the Ariane rockets. The manufacturing process entails many welds. Weld-simulations have been made to investigate stresses and plastic strains on simplified geometries. Plastic strains have been evaluated parallel and normal to the weld for plate geometries of shell-elements with rectangular cross-section and sandwich-cross-section, using the FEM-program MSC.marc. Results shows that plate width and length have negligible effect on the plastic strains when one weld is made. A comparison between a sandwich-sector cone and a sandwich plate was made, to investigate how plastic strains and stresses were affected of geometry. Plastic strains and stresses parallel the weld are the same. Plastic strains and stresses normal the weld are affected by changing geometry. Studies on differences in stresses between solid and shell elements propose use of solid elements near the weld region, if stresses are of interest.
12
Dharmawan, Ferry, and ferry dharmawan@rmit edu au. "The Structural Integrity And Damage Tolerance Of Composite T-Joints in Naval Vessels." RMIT University. Aerospace, Mechanical and Manufacturing Engineering, 2008. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20081216.163144.
Full textAbstract:
In this thesis, the application of composite materials for marine structures and specifically naval vessels has been explored by investigating its damage criticality. The use of composite materials for Mine Counter Measure Vessels (MCMVs) was desirable, especially for producing material characteristics, such as light weight, corrosion resistance, design flexibility due to its anisotropic nature and most importantly stealth capability. The T-Joint structure, as the primary connection between the hull and bulkhead forms the focus of this research. The aim of the research was to determine the methodology to predict the damage criticality of the T-Joint under a pull-off tensile loading using FE (Finite Element) based fracture mechanics theory. The outcome of the research was that the Finite Element (FE) simulations were used in conjunction with fracture mechanics theory to determine the failure mechanism of the T-Joint in the presence of disbonds in the critical loca tion. It enables certain pre-emptive strengthening mechanisms or other preventive solutions to be made since the T-Joint responses can be predicted precisely. This knowledge contributes to the damage tolerance design methodology for ship structures, particularly in the T-Joint design. The results comparison between the VCCT (Virtual Crack Closure Technique) analysis and the experiment results showed that the VCCT is a dependable analytical method to predict the T-Joint failure mechanisms. It was capable of accurately determining the crack initiation and final fracture load. The maximum difference between the VCCT analysis with the experiment results was approximately 25% for the T-Joint with a horizontal disbond. However, the application of the CTE (Crack Tip Element) method for the T-Joint displayed a huge discrepancy compared with the results (fracture toughness) obtained using the VCCT method, because the current T-Joint structure geometry did not meet the Classical Laminate Plate Theory (CLPT) criteria. The minimum fracture toughness difference for both analytical methods was approximately 50%. However, it also has been tested that when the T-Joint structure geometry satisfied the CLPT criteria, the maximum fracture toughness discrepancy between both analytical methods was only approximately 10%. It was later discovered from the Griffith energy principle that the fracture toughness differences between both analytical methods were due to the material compliance difference as both analytical methods used different T-Joint structures.
13
Dong, Fangxiao. "KINETICS OF WEDGE-TEE JOINT FORMATION DURING BRAZING OF AN ALUMINUM ALLOY UNDER CONTROLLED ATMOSPHERE." UKnowledge, 2013. http://uknowledge.uky.edu/me_etds/23.
Full textAbstract:
This work involves investigation of the kinetics data of a joint formation during aluminum alloy brazing. Data was generated by several groups of experiments conducted under conditions of a controlled oxygen level of the background brazing atmosphere. Generated data are examined to identify the phases of the joint formation and the time frame of its evolution. Specifically, the triple line kinetics data are analyzed to verify whether a power law between (1) the triple line of the molten metal preceding joint formation and (2) the formation time can be established for each formation phase. In addition, both initial and residual clad thicknesses on brazing sheets are studied to check phenomenologically an impact of silicon diffusion on joint formation. Formation shapes are also inspected in order to study if a 2-D configuration of joint formation is present. The kinetics data from different sets of experiments under adverse atmosphere conditions are compared to understand the impact of oxygen level on joint formation. This study is not necessarily aimed at building a mathematical model for T-Joint formation during brazing process, but intends to understand possible influential parameters on the development of the formation.
KEYWORDS: Aluminum Brazing, Kinetics, T-Joint, Background Atmosphere, Capillary Flow.
14
Casula, V. (Victor). "Quantitative magnetic resonance imaging methods for evaluation of articular cartilage in knee osteoarthritis:free-precession and rotating-frame relaxation studies at 3 Tesla." Doctoral thesis, Oulun yliopisto, 2016. http://urn.fi/urn:isbn:9789526213521.
Full textAbstract:
Abstract Osteoarthritis (OA) is a common chronic condition that reduces the quality of life of millions of individuals worldwilde. In OA, the progressive degradation of articular cartilage (AC) and bone can cause joint pain and disability. Currently there is no effective treatment available for OA besides gross joint replacement surgery. This is largely due to the lack of accurate biomarkers to test potential drugs and treatments that could stop or reverse the disease progression. The primary tools in use for OA diagnostics are inadequate in the early stage of the disease and merely allow its late manifestations to be visualized. Quantitative MRI (qMRI) has demonstrated the ability to distinguish degenerated from intact AC prior to radiographic changes. Moreover, so-colled rotating frame relaxation time parameters are sensitive to the slow molecular motion domain, relevant for clinical applications. T1ρ and T2ρ relaxation time measurements using adiabatic spin-lock pulses (AdT1ρ and AdT2ρ) have shown superior sensitivity to cartilage degeneration in vitro over conventional qMRI parameters. This thesis aimed to compare the differences that exist between established qMRI methods for AC against arthroscopic evaluation as well as optimize and validate AdT1ρ and AdT2ρ mapping of cartilage in vivo. The findings showed that T1 and T2 relaxation time and delayed gadolinium enhanced MRI of cartilage (dGEMRIC) were able to discriminate among different arthroscopic grades of cartilage lesions. However, arthroscopic findings and qMRI parameters were not correlated, supporting the viewpoint that qMRI may be able to elicit more comprehensive information on the quality of remaining cartilage tissue as compared to diagnostic arthroscopy, which detects cartilage loss. AdT1ρ and AdT2ρ mapping of cartilage in vivo were successfully implemented and validated on a clinical MRI system. AdT1ρ and AdT2ρ were able to overcome limitations of the existing methods (continuous wave spin-lock approach), which are challenging to implement on clinical settings for their susceptibility to field inhomogeneity and relatively high power deposition in tissue. The association of AdT1ρ and AdT2ρ with cartilage and bone marrow lesions and osteophytes was demonstrated. The findings indicate the utility of AdT1ρ and AdT2ρ mapping as potential biomarkers for evaluation of early cartilage degeneration in OA research and clinical applicationsTiivistelmä Nivelrikko on tavallinen krooninen sairaus, joka huonontaa miljoonien ihmisten elämänlaatua ympäri maailman. Nivelrikossa nivelruston ja luun asteittain etenevä rappeuma voi aiheuttaa nivelkipua ja liikuntakyvyttömyyttä. Tällä hetkellä nivelrikkoon ei ole muuta tehokasta hoitokeinoa kuin tekonivelleikkaus. Tämä johtuu suuremmaksi osaksi tarkkojen biomarkkereiden puutteesta, joiden avulla voitaisiin kokeilla mahdollisia nivelrikon pysäyttäviä tai tautia parantavia lääkkeitä tai hoitokeinoja. Nykyisin nivelrikon diagnostiikassa käytetyimmät menetelmät ovat riittämättömiä sairauden alkuvaiheessa, ja ne tunnistavat vain sairauden loppuvaiheet. Kvantitatiivisilla magneettikuvausmenetelmillä pystytään erottamaan rappeutunut ja ehjä nivelrusto toisistaan ennen röntgenkuvissa havaittavia muutoksia. Nk. pyörivän koordinaatiston relaksaatioaikaparametrit ovat herkkiä havaitsemaan hidasta molekyyliliikettä, jolla on merkitystä kliinisissä sovelluksissa. Kokeellisissa olosuhteissa T1ρ- ja T2ρ-relaksaatioaikojen mittaaminen käyttäen adiabaattisia spin-lukkopulsseja (AdT1ρ ja AdT2ρ) on osoittautunut erityisen tarkaksi nivelruston rappeutumisen toteamiseksi verrattuna perinteisiin kvantitatiivisiin magneettikuvausmenetelmiin. Tämän väitöskirjan tavoitteena oli vertailla vakiintuneita nivelrikon kvantitatiivisia magneettikuvausmenetelmiä sekä optimoida ja validoida AdT1ρ- ja AdT2ρ-menetelmien käyttöä ihmisen ruston tutkimisessa. Tulokset osoittivat, että T1- ja T2-relaksaatioajat sekä varjoainetehosteinen nivelruston magneettikuvaus pystyivät erottelemaan niveltähystyksessä määritettyjä nivelrikon eri asteita. Kuitenkaan niveltähystyslöydökset ja kvantitatiiviset magneettikuvausparametrit eivät korreloineet viitaten kvantitatiivisen magneettikuvauksen kykyyn osoittaa tarkemmin jäljellä olevan ruston laatua verrattuna niveltähystykseen, jossa arvioidaan ruston puutosta. Nivelruston AdT1ρ- ja AdT2ρ-relaksaatioaikamittaukset onnistuttiin suorittamaan ja validoimaan vapaaehtoisilla koehenkilöillä kliinisellä magneettikuvauslaitteella. AdT1ρ ja AdT2ρ eivät kärsineet samoista puutteista kuin tavanomaiset jatkuva-aaltoiset spin-lukkomenetelmät, joka ovat herkkiä kenttäepähomogeenisuuksille ja aiheuttavat suuremman radiotaajuusaltistuksen. Tutkimuksessa osoitettiin AdT1ρ- ja AdT2ρ-mittausten ja luuödeemin sekä osteofyyttien välinen yhteys. Tulokset osoittivat, että AdT1ρ- ja AdT2ρ-mittaukset ovat potentiaalisia biomarkkereita varhaisen nivelruston rappeuman havaitsemiseksi tutkimus- ja kliinisessä käytössä
15
Sun, Tianzhu. "Residual stress development in AA7050 stationary shoulder friction stir welds." Thesis, University of Manchester, 2018. https://www.research.manchester.ac.uk/portal/en/theses/residual-stress-development-in-aa7050-stationary-shoulder-friction-stir-welds(9c4066c2-f3cf-4a3d-bfd0-3f6842de1251).html.
Full textAbstract:
Stationary shoulder friction stir welding (SSFSW) is a recently developed variant of conventional friction stir welding (FSW). Recent studies have shown that SSFSW can join high strength aluminum alloys with improved mechanical strength and reduced distortion as a result of a narrower and more uniform thermal profile. However, a lack of understanding on the residual stress development in the SSFSW process makes it difficult to assess the structural integrity and delays a widespread application of this technique to industry. This dissertation reports the first systematic investigation into the development of residual stress induced by the SSFSW process and comparison between SSFSW and FSW techniques. Welding residual stresses were experimentally assessed with both the contour method and neutron diffraction. The weld microstructure and hardness distributions were characterized and used to understand the formation of residual stresses during the welding process. The results have shown that for both FSW and SSFSW processes, the residual stresses distribute in the form of âMâ shaped profile while the magnitude and size of tensile residual stress zone were effectively reduced (by 25%) in the SSFSW process, even when input welding power was identical. Other improvements seen in the SSFSW process include a reduction in the heat affected zone width, an increase in the minimum hardness and a more uniform through-thickness microstructure and hardness. The dominating welding process parameter affecting the welding residual stress was travel speed as compared to rotation speed and tool downforce. With a 90 degree shaped shoulder, SSFSW has been shown to produce defect-free T-sections by dual fillet welds. For these components, an asymmetrical distribution of microstructure, hardness and residual stresses were found as a consequence of the thermal effects induced by second weld on the first weld. The material softening caused by the first weld provides the potential of utilizing a lower heat input on the subsequent pass so as to optimize the welding parameters.
16
Martins, Meco Sonia Andreia. "Joining of steel to aluminium alloys for advanced structural applications." Thesis, Cranfield University, 2016. http://dspace.lib.cranfield.ac.uk/handle/1826/10288.
Full textAbstract:
When joining steel to aluminium there is a reaction between iron and aluminium which results in the formation of brittle intermetallic compounds (IMC). These compounds are usually the reason for the poor mechanical strength of the dissimilar metallic joints. The research on dissimilar metal joining is vast but is mainly focused on the automotive industry and therefore, the material in use is very thin, usually less than 1 mm. For materials with thicker sections the present solution is a transition joint made by explosion welding which permits joining of steel to aluminium and avoids the formation of IMCs. However, this solution brings additional costs and extra processing time to join the materials. The main goals of this project are to understand the mechanism of formation of the IMCs, control the formation of the IMCs, and understand their effects on the mechanical properties of the dissimilar Fe-Al joints during laser welding. Laser welding permits accurate and precise control of the welding thermal cycle and thereby the underpinning mechanism of IMC formation can be easily understood along with the factors which control the strength of the joints. The further goal of this project is to find an appropriate interlayer to restrict the Fe-Al reaction. The first stage of the work was focused on the formation and growth of the Fe-Al IMCs during laser welding. The understanding of how the processing conditions affect the IMC growth provides an opportunity to act and avoid its formation and thereby, to optimize the strength of the dissimilar metal joints. The results showed that even with a negligible amount of energy it was not possible to prevent the IMC formation which was composed of both Fe2Al5 and FeAl3 phases. The IMC growth increases exponentially with the applied specific point energy. However, for higher power densities the growth is more accentuated. The strength of the Fe-Al lap-joints was found to be not only dependent on the IMC layer thickness but also on the bonding area. In order to obtain sound joints it is necessary to achieve a balance between these two factors. The thermal model developed for the laser welding process in this joint configuration showed that for the same level of energy it is more efficient to use higher power densities than longer interaction iv times. Even though a thicker IMC layer is formed under this condition due to higher temperature there is also more melting of aluminium which creates a larger bonding area between the steel and the aluminium. The joint strength is thus improved ... [cont.].
17
Saberi, Sina. "Analysis of Unreinforced and Reinforced Tubular T-Joints Structures with Open Source Finite Element Software." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021.
Find full textAbstract:
Tubular Joints play quite a vital role in most of the marine structures. It is obvious that having full control about the capacity and strength of tubular joints would be very worthy to have good knowledge about the total performance of the structure. In recent years the application of the finite element method has become very popular in the analyses of different types of welded circular tubular joints. The rapid development of FE programs and computation facilities has extended the analyses in the study of stress distribution and load-displacement behavior of a joint to the assessment of the ultimate capacity. This thesis presents a numerical investigation using open source finite element analysis on tubular joints that are the main structural components of steel offshore structures. The studied joint is reinforced and unreinforced T-joint. In nowadays, several types of reinforcement are available to enhance the strength of tubular joints. Thus, for a better understanding of the static strength of joints, two common types of reinforcement plate (doubler and collar) were investigated. In this regards twelve T-Joint specimens subjected to axial brace load (6 in compression and 6 in tension) have been studied, with the different geometric, material property, and reinforced plate. In addition, different types of shell and solid finite elements are considered in this investigation. The shell elements are the linear triangular and quadrilateral elements and the solid elements are the linear tetrahedral and hexahedral elements. Also, this study was performed to investigate and report the usefulness of the open-source software programs Code\_Aster and Salome-Meca in implementing static finite element modeling of tubular joints.
18
Moradi, Eshkafti Milad Verfasser], and Hartmut [Gutachter] [Pasternak. "Influence of various welding sequence schemes on the load bearing capacity of square hollow section T-joint / Milad Moradi Eshkafti ; Gutachter: Hartmut Pasternak." Cottbus : BTU Cottbus - Senftenberg, 2018. http://d-nb.info/1151520985/34.
Full text
19
Andersson, Lassila Andreas, and Marcus Folcke. "Numerical and experimental analysis of adhesively bonded T-joints : Using a bi-material interface and cohesive zone modelling." Thesis, Högskolan i Skövde, Institutionen för ingenjörsvetenskap, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-15280.
Full textAbstract:
With increasing climate change the automotive industry is facing increasing demands regarding emissions and environmental impact. To lower emissions and environmental impact the automotive industry strives to increase the efficiency of vehicles by for example reducing the weight. This can be achieved by the implementation of lightweight products made of composite materials where different materials must be joined. A key technology when producing lightweight products is adhesive joining. In an effort to expand the implementations of structural adhesives Volvo Buses wants to increase their knowledge about adhesive joining techniques. This thesis is done in collaboration with Volvo Buses and aims to increase the knowledge about numerical simulations of adhesively bonded joints. A numerical model of an adhesively bonded T-joint is presented where the adhesive layer is modelled using the Cohesive Zone Model. The experimental extraction of cohesive laws for adhesives is discussed and implemented as bi-linear traction-separation laws. Experiments of the T-joint for two different load cases are performed and compared to the results of the numerical simulations. The experimental results shows a similar force-displacement response as for the results of the numerical simulations. Although there were deviations in the maximum applied load and for one load case there were deviations in the behavior after the main load drop. The deviations between numerical and experimental results are believed to be due to inaccurate material properties for the adhesive, the use of insufficient bi-linear cohesive laws, the occurrence of a combination of adhesive and cohesive fractures during the experiments and dissimilar effective bonding surface areas in the numerical model and the physical specimens.
20
Mi, Yongcui. "Novel beam shaping and computer vision methods for laser beam welding." Licentiate thesis, Högskolan Väst, Avdelningen för produktionssystem (PS), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-16970.
Full textAbstract:
Laser beam welding has been widely applied in different industrial sectors due to its unique advantages. However, there are still challenges, such as beam positioning in T-joint welding, and gap bridging in butt joint welding,especially in the case of varying gap width along a joint. It is expected that enabling more advanced control to a welding system, and obtaining more in-depth process knowledge could help to solve these issues. The aim of this work is to address such welding issues by a laser beam shaping technology using a novel deformable mirror together with computer vision methods and also to increase knowledge about the benefits and limitations with this approach. Beam shaping in this work was realized by a novel deformable mirror system integrated into an industrial processing optics. Together with a wave front sensor, a controlled adaptive beam shaping system was formed with a response time of 10 ms. The processes were monitored by a coaxial camera with selected filters and passive or active illumination. Conduction mode autogenous bead-on-plate welding and butt joint welding experiments have been used to understand the effect of beam shaping on the melt pool geometry. Circular Gaussian, and elliptical Gaussian shapes elongated transverse to and along the welding direction were studied. In-process melt pool images and cross section micrographs of the weld seams/beads were analyzed. The results showed that the melt pool geometry can be significantly modified by beam shaping using the deformable mirror. T-joint welding with different beam offset deviations relative to the center of the joint line was conducted to study the potential of using machine learning to track the process state. The results showed that machine learning can reach sufficient detection and estimation performance, which could also be used for on-line control. In addition, in-process and multidimensional data were accurately acquired using computer vision methods. These data reveal weaknesses of current thermo-fluid simulation model, which in turn can help to better understand and control laser beam welding. The obtained results in this work shows a huge potential in using the proposed methods to solve relevant challenges in laser beam welding.Lasersvetsning används i stor utsträckning i olika industrisektorer på grund av dess unika fördelar. Det finns emellertid fortfarande utmaningar, såsom rätt positionering av laserstrålen vid genomträngningssvetsning av T-fogar och hantering av varierande spaltbredd längs fogen vid svetsning av stumfogar. Sådana problem förväntas kunna lösas med avancerade metoder för automatisering, metoder som också förväntas ge fördjupade kunskaper om processen. Syftet med detta arbete är att ta itu med dessa problem med hjälp av en teknik för lasereffektens fördelning på arbetsstycket, s.k. beam shaping. Det sker med hjälp av en ny typ av i realtid deformerbar spegel tillsammans med bildbehandling av kamerabilder från processen. För- och nackdelar med detta tillvägagångssätt undersöks.Beam shaping åstadkoms med hjälp av ny typ av deformerbart spegelsystem som integreras i en industriell processoptik. Tillsammans med en vågfrontsensor bildas ett adaptivt system för beam shaping med en svarstid på 10 ms. Processen övervakas av en kamera linjerad koaxialt med laserstrålen. För att kunna ta bilder av svetspunkten belyses den med ljus av lämplig våglängd, och kameran är försedd med ett motsvarande optiskt filter. Försök har utförts med svetsning utan tillsatsmaterial, direkt på plåtar, svetsning utan s.k. nyckelhål, för att förstå effekten av beam shaping på svetssmältans geometri. Gauss fördelade cirkulära och elliptiska former, långsträckta både tvärs och längs svetsriktningen har studerats. Bilder från svetssmältan har analyserats och även mikrostrukturen i tvärsnitt från de svetsade plåtarna. Resultaten visar att svetssmältans geometri kan modifieras signifikant genom beam shaping med hjälp av det deformerbara spegelsystemet. Genomträngningssvetsning av T-fogar med avvikelser relativt foglinjens centrum genomfördes för att studera potentialen i att använda maskininlärning för att fånga processens tillstånd. Resultaten visade att maskininlärning kan nå tillräcklig prestanda för detektering och skattning av denna avvikelse. Något som också kan användas för återkopplad styrning. Flerdimensionell processdata har samlats i realtid och analyserats med hjälp av bildbehandlingsmetoder. Dessa data avslöjar brister i nuvarande simuleringsmodeller,vilket i sin tur hjälper till med att bättre förstå och styra lasersvetsning.Resultaten från detta arbete uppvisar en god potential i att använda de föreslagna metoderna för att lösa relevanta utmaningar inom lasersvetsning.
Till licentiatuppsats hör 2 inskickade artiklar, som visas inte nu.
21
Griethe, Mathias. "Morphometrische Vermessungen von MRT-Aufnahmen des Kiefergelenks." Doctoral thesis, [S.l.] : [s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=976486822.
Full text
22
Nizer, Adriano. "Avaliação da influência do esforço normal no banzo no comportamento de ligações tubulares em aço." Universidade do Estado do Rio de Janeiro, 2014. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=7761.
Full textAbstract:
A demanda pelo uso de perfis tubulares em estruturas na construção civil tem tido grande avanço no Brasil, apesar de ser, há muito tempo, amplamente empregado na Europa e países desenvolvidos. O lançamento de uma norma técnica brasileira específica para dimensionamento de perfis tubulares confirma esta tendência, havendo então a necessidade de uma maior divulgação e execução de estudos e trabalhos de pesquisa para uma melhor compreensão e desenvolvimento desta tecnologia. O presente trabalho apresenta uma análise da influência da aplicação de esforço normal no banzo no comportamento de ligações tubulares do tipo T. No desenvolvimento deste trabalho, foram realizados seis ensaios em laboratório com ligações do tipo T com perfis do tipo RHS para o banzo e SHS para o montante, sendo utilizados perfis conformados a frio para composição das ligações ensaiadas. Do total dos ensaios foram executados dois ensaios sem aplicação de esforço normal no banzo; dois com aplicação de esforço normal de compressão e dois com aplicação de esforço normal de tração. A resistência última das ligações nos ensaios foi obtida por meio do Critério de Deformação Limite proposto por diversos pesquisadores. Estes resultados foram comparados com os resultados obtidos em modelos numéricos em elementos finitos desenvolvidos no programa ANSYS 12.0, sendo considerado nestes modelos as não-linearidades geométricas e de material. Estes resultados também foram comparados com os resultados teóricos obtidos com base nas prescrições constantes nas normas Eurocode 3; norma brasileira NBR 16239 e do CIDECT. Conclui-se com este estudo que os resultados obtidos tanto nos ensaios experimentais quanto nos modelos numéricos ficaram a favor da segurança quando comparados com os valores teóricos obtidos pelas normas Eurocode 3 e NBR 16239:2013 e CIDECT com o banzo sem aplicação de esforço normal e com aplicação de esforço normal de compressão de até 60% e 80 % da carga de plastificação do banzo, respectivamente, para o Eurocode 3/NBR16239:2013 e para o CIDECT. As resistências obtidas para as ligações com a aplicação de esforço normal de tração no banzo foram superiores aos resultados teóricos no caso estudado.The demand for the use of hollow sections structures in construction has had great progress in Brazil, despite being a long time widely used in Europe and developed countries. The release of a Brazilian Technical Standard specific for design of hollow sections, confirms this trend, and the need for increased dissemination and implementation of studies and research for a better understanding and development of this technology. This paper presents an analysis of the influence of chord normal stresses on the behavior of hollow sections connections, specifically for a T tubular joint. The experimental program consisted of six tests where two experiments were executed without chord axial forces, two were performed with compressive axial forces and two tension axial forces. The tested joints ultimate strengths were determined using deformation limit criteria proposed by several researchers. These results were then compared to the results obtained from a finite element numerical model developed 12.0 ANSYS program that included geometrical and material nonlinearities. These results were also compared to the design provisions present at the Eurocode 3; Brazilian standard NBR 16239:2013 and CIDECT. This assessment indicated that the results obtained in both experimental tests and in the numerical models were in favor of security when compared to the theoretical values obtained by all the investigated standards for chords without axial forces and with compressive axial forces corresponding to 60% and 80% of the chord plastic resistance, respectively, according to Eurocode 3/NBR16239:2013 and CIDECT. The obtained resistances for the joints applying tensile axial force on the chord were superior to the predicted theoretical results in the studied cases.
23
Thummalapalli, Vimal Kumar. "Biomimetic Composite T-Joints." University of Dayton / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1323547304.
Full text
24
Edwards, Katherine. "Optimization and packings of T-joins and T-cuts." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=104686.
Full textAbstract:
Let G be a graph and T an even cardinality subset of its vertices. We call (G,T) a graft. A T-join is a subgraph of G whose odd-degree vertices are precisely those in T, and a T-cut is a cut delta(S) where S contains an odd number of vertices of T. An interesting question from a combinatorial optimization perspective is that of finding optimal T-joins and T-cuts. These have applications in various places. We give an overview of several such optimization problems, as well as several algorithms for finding optimal T-joins and T-cuts from the literature.We then consider a packing problem in grafts. It is a simple observation that the number of edge-disjoint T-joins is at most the number of edges in any T-cut. However it is not known exactly when these quantities are equal. It has been conjectured by Guenin that if G is planar and all T-cuts of G have the same parity and the size of every T-cut is at least k, then G contains k edge-disjoint T-joins. The case k = 3 is equivalent to the Four Colour Theorem, and the cases k = 4, which was conjectured by Seymour, and k = 5 were proved by Guenin. Recently, the case k = 6 was settled by Dvorak, Kawarabayashi and Kral. In this thesis, we give a proof of the case k = 7.Soit G un graphe, et T un sous-ensemble de ses sommets de cardinalité pair. Nous appelons (G,T) une greffe. Définissons par T-jointure tout sous-graphe de G dans lequel les sommets de degré impair sont précisement ceux de l'ensemble T, et par T-coupure tout coupure delta(S) où S contient un nombre impair de sommets de T. Une question intéressante en optimisation combinatoire est celle de trouver les T-jointures et T-coupures optimales. Nous donnons un aperçu de divers problèmes d'optimisation auxquels ceux-ci s'appliquent, ainsi que plusieurs algorithmes pour trouver les T-jointures et T-coupures optimales.Nous considérons ensuite un problème d'empaquetage dans les greffes. C'est une observation facile que le nombre de T-jointures arête-disjointes dans le graphe G est au maximum le nombre d'arêtes dans quelconque T-coupure. Cependant on ne sait pas exactement quand ces quantités sont égales. Il a été conjecturé par Guenin que si G est planaire, que tous les T-coupures de G ont la même parité et que et le nombre d'arêtes dans chaque T-coupure est au moins k, alors G contient k T-jointures arête-disjointes. Quand k = 3 la question est équivalente au théorème des quatre couleurs, et le cas k = 4, ce qui a été conjecturé par Seymour, et k = 5 ont été prouvés par Guenin. Récemment, le cas k = 6 a été réglé par Dvorak, Kawarabayashi et Kral. Dans cette thèse, nous donnons une preuve pour le cas k = 7.
25
Sahboun, Salahaddin. "V-band joint torsional load capacity." Thesis, University of Huddersfield, 2015. http://eprints.hud.ac.uk/id/eprint/28321/.
Full textAbstract:
This research thesis presents an analysis of the torsional loads on V-band clamps. In some applications, the relative rotational movement of the flanges connected by V-band clamps can result in catastrophic system failure. The ability to understand the factors impacting on torsional load capacity is therefore essential. In this research project, a theoretical model of a V-band joint subjected to torsional loads was developed. This model is used to identify those parameters that will impact on the joint’s reliability. An experimental investigation was conducted to validate a theoretical model using a newly developed test rig. The development and features of this test rig are presented in this report. This experimental investigation also allowed the impact of those parameters that are difficult to control, to be determined. A total of three V-bands were used with different diameters but nominally identical cross sections were studied. In the research results, the initial slip point between flanges and the V-band clamp was identified by experimentation within this research project. Different sizes of Vbands were used under boundary conditions and loads. From the simulation results it was determned that the friction effect on the V-band depends on the size of the V-band. For the largest size of V-band, there was moderate correlation of the experimental and theoretical results. For the smallest size, the results suggest that with band tightening, flange contact is localised, rather than being throughout the band’s entire circumference. The research demonstrated the significant relevance of the band and flanges’ contact points and the coefficient of friction, especially that between the flanges, on the V-band clamp’s theoretical torsional load capacity.
26
Palosaari, K. (Kari). "Quantitative and semiquantitative imaging techniques in detecting joint inflammation in patients with rheumatoid arthritis:phase-shift water-fat MRI method for fat suppression at 0.23 T, contrast-enhanced dynamic and static MRI, and quantitative 99mTc-nanocolloid scintigraphy." Doctoral thesis, University of Oulu, 2008. http://urn.fi/urn:isbn:9789514288623.
Full textAbstract:
Abstract
The purpose of this study was to evaluate the value of 0.23T low-field magnetic resonance imaging (MRI) and nanocolloid (NC) scintigraphy in assessing joint pathology associated with rheumatoid arthritis (RA).
Fat suppression methods combined with contrast media enhancement aid in distinguishing enhancing inflamed tissue from the surrounding fat, especially in the imaging of arthritic joints. The feasibility and image quality of a phase-shift water-fat MRI method for fat suppression at low-field 0.23T open configuration MR scanner was evaluated. The technique was combined with contrast-enhanced imaging to assess the conspicuity of synovial hypertrophy in the joints of 30 RA patients. Improved conspicuity and delineation of synovitis was detected with this method. However, because of a great amount of manual post processing, future development is needed to make this method more feasible.
Contrast-enhanced MRI and NC scintigraphy may provide objective and quantitative information about the inflammatory activity in arthritic joints. The value of quantitative and semiquantitative measures of inflammation derived from NC scintigraphy and low-field MRI of the wrist joint of 28 early RA patients was evaluated. Furthermore, it was investigated whether these parameters have predictive value of further erosive development during two years of follow-up.
Strong correlations were detected between the NC scintigraphy and MRI measures, and these parameters were associated with laboratory markers of inflammation. During the two-year follow-up, the initial MRI and NC scintigraphy measures were closely related with the progression of wrist joint erosions.
Small erosive-like bone defects can occasionally be found in wrist MRI of patients without clinically overt arthritis. The prevalence of these lesions was studied in bilateral wrist MRI examinations of 31 healthy persons. Small lesions resembling erosions were detected in 14 out of 31 subjects. Altogether 24 of the 930 wrist bones evaluated showed such lesions (3%). Thus small changes resembling erosions can be found in the wrist MRI of healthy subjects; the significance of these findings must always be interpreted with reference to the clinical picture.
In conclusion, early RA patients with high local inflammatory activity, as detected by NC scintigraphy and MRI are at risk of developing further bone damage. Furthermore, in the follow-up of early RA patients, if clinically sustained response is not achieved, these methods help to identify patients who need more intensive drug treatment.
27
Payne, J. G. "Residual stresses in welded tubular T-joints." Thesis, University of Cambridge, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384523.
Full text
28
Maczugowski, Maciej. "Numerical simulation of residual stresses in a weld seam : An application of the Finite Element Method." Thesis, Linnéuniversitetet, Institutionen för maskinteknik (MT), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-65867.
Full textAbstract:
Articulated haulers are fundamental equipment to transport material. The load carrying structure on a hauler consists mainly of welded frames. During welding of the frames high residual stress will be introduced. These stresses may have a significant impact on the fatigue life of the frames. This is the reason for having good knowledge of the weld residual stresses. The finite element method was used to calculate the residual stress distributions in a butt weld and a T-join weld. Simulation of the welding process with thermal and mechanical analysis was prepared by means of welding GUI implemented in LS-PrePost. The welding simulation is a computer intensive operation with high CPU time. That is why it is important to investigate which process factors that have the largest impact on welding simulation results. The aim of this thesis is to investigate the correlation between designed models in FEA software with published results of weld residual stress measurements and conclude which parameters should be mainly taken into consideration.
29
Ciocanel, Despina E. "Atlantoaxial instability : biomechanical evaluation of T-Plate versus transarticular screw fixation." Connect to full-text via OhioLINK ETD Center, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=mco1116798081.
Full textAbstract:
Thesis (M.S.)--Medical College of Ohio, 2005."In partial fulfillment of the requirements for the degree of Master of Science in Biomedical Sciences." Major advisor: Nabil Ebraheim. Includes abstract. Document formatted into pages: iii, 57 p. Title from title page of PDF document. Bibliography: pages 35-42,49-56.
30
Saeid, Ali A. "Modeling the Progressive Damage in Biomimetic Composite Sandwich T-Joints." University of Dayton / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1461310482.
Full text
31
McFall, Bruce Daniel. "The Effects of Multi-Axial Loading on Adhesive Joints." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1515074800550415.
Full text
32
Gibson, Kathryn. "The pathogenic potential of endogenous-self reactive CD4 T cells in collagen-induced arthritis." Thesis, King's College London (University of London), 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.313722.
Full text
33
Jung, Gonghyun. "Plasticity-Based Distortion Analysis for Fillet Welded Thin Plate T-Joints." The Ohio State University, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=osu1047434566.
Full text
34
Dickinson, Alexander. "Development of computational biomechanical tools to assess the performance of the resurfaced hip joint." Thesis, University of Southampton, 2011. https://eprints.soton.ac.uk/185115/.
Full text
35
Cheng, Shumin. "Non-destructive evaluation of cracking in tubular T-joints using vibration procedures." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ34244.pdf.
Full text
36
Saad, Sariffuddin Bin. "Finite element determination of the static strength of cracked tubular T-joints." Thesis, University of Nottingham, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.362919.
Full text
37
Militaru, Daniel Valentin Carleton University Dissertation Engineering Mechanical and Aerospace. "Hammer peening effects on the fatigue life of welded t-plate joints." Ottawa, 1994.
Find full text
38
Llewelyn-Parry, A. "Behaviour and strength of stiffened tubular T- and DT-joints in offshore structures." Thesis, Swansea University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.637938.
Full textAbstract:
This thesis addresses the understanding of the static strength and behaviour of internally ring stiffened T- and DT-joints under axial brace loading. Initial numerical work verifies the appropriateness of the Finite Element (F.E.) modelling technique and the use of the F.E. Method as an analysis tool. This was achieved through a validation study on both unstiffened and ring stiffened T-joints and on unstiffened DT-joints. There follows four substantial parametric studies on ring stiffened T- and DT-joints which investigate the effect of the variation of the stiffener dimensions of plain and T-shaped stiffeners along with the joint geometrical parameters β and γ on the strength and behaviour of the stiffener and the stiffened joint. Also the number and position of the ring stiffeners are investigated. Findings of the study enabled, where appropriate, the proposal of two methods of strength prediction for the ring stiffener. One uses Plastic Theory to postulate a ring model which is based on a five- or six-hinge failure mechanism for the stiffener, resulting in a virtual Work Equation. For this method it is assumed that a portion of the chord interacts with the stiffener in producing the strength enhancement. The stiffener cross-section is then considered as a T- and an I-section for the plain and T-shaped stiffeners respectively. The other is an empirical equation based on the variation of the non-dimensional stiffener strength with the various influencing non-dimensional parameters. It has been shown that the theoretical method can be compromised when the stiffener parameters exceed the validity range of the predictive method whereas the empirical method appears to be more robust to extrapolation of the validity ranges. Both methods provide accurate predictions of stiffener strength when compared to the newly created FE database and existing test and numerical results.
39
Li, Qian. "Finite Deformations of Fiber-Reinforced Rubberlike Solids, and of Adhesively Bonded T-peel Joints." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/82923.
Full textAbstract:
Fiber-reinforced rubberlike materials (FRRM) commonly used in tires undergo large deformations, and exhibit different response in tension and compression along the fiber direction. Assuming that the response of a fiber-reinforced rubberlike material can be modeled as transversely isotropic with the fiber direction as the axis of transverse isotropy, we express the stored energy function, W, in terms of the five invariants of the right Cauchy-Green strain tensor and the fiber direction, and account for different response in tension and compression along the fiber direction. It has been shown in the literature that in shear-dominated deformations, the 5th invariant, I5, significantly contribution to the stress-strain curve. We have implemented the constitutive relation in the commercial software, LS-DYNA. The numerical solutions of several boundary value problems studied here agree with their analytical solutions derived by using Ericksen's inverse approach, in which a part of the solution is assumed and unknowns in the presumed solution are then found by analyzing the pertinent boundary value problem. However, computed results have not been compared with experimental findings.
For W of the FRRMs an expression that is a complete quadratic function of the five invariants is also examined. Homogeneous deformations such as simple extension, simple shear, and biaxial loading problems are studied to delineate the mechanical behaviors of FRRMs. Consistency with the infinitesimal deformation theory requires that linear terms in the 4th and 5th invariants, I4 and I5, be included in the expression for W. Stability analysis of deformations reveals the qualitative changes triggered by the second order terms of the quadratic function. Analytical solutions for inflation, extension and twist deformations caused by internal pressure, end torque, and axial force for a pressurized cylindrical laminate are derived using Ericksen's inverse method. Effects of fiber orientations on the mechanical behaviors of a +/-α angle-ply cylindrical tube are investigated using the derived analytical solutions.
The T-peel test, widely used for characterizing adhesion across a plethora of adhesives, adherends, and geometries, results in a range of responses that may complicate meaningful interpretation of the test data. This research effort, involving several specific specimen types, was undertaken to investigate concerns that commonly used configurations may not always result in plateaus in the force-displacement response. We experimentally and numerically study debonding of T-peel specimens having 75 mm bond length and 0.81 mm thick adherends made of either 6061 aluminum (Al) or one of the three steels (G70 70U hot dip galvanized, E60 elctrogalvanized (EGZ), 1010 cold-rolled steel (CRS) bonded with either LORD® 406 or Maxlok™ acrylic adhesive. For the EGZ and the Al adherends, specimens with a bond length of 250 mm and adherend thickness of 1.60 mm are also examined. Effects of adherend materials and thicknesses, bond lengths, and adhesives on test results are examined using three metrics to interpret the T-peel bond performance. We find a limited correlation between the commonly used "T-peel strength" and the energy dissipated per unit debond area. For those two metrics, the relative performances of the CRS and the Al specimens are quite different. Quasi-static plane strain deformations of the test specimens are analyzed by the finite element method (FEM) and a cohesive zone model using the commercial software, ABAQUS, to help interpret the test data. Numerical results provided energies required to elastically and plastically deform the adherends, and help determine the transition from non-self-similar to self-similar debonding. The FE simulations also facilitate determination of the fraction of the crosshead displacement at which self-similar debonding occurs. Results reported herein should help practitioners select appropriate specimen dimensions for extracting meaningful data for adhesive performance.Ph. D.
40
Fu, Bin. "Advanced fracture mechanics analysis of shallow surface cracks in fillet welded T-butt plate joints." Thesis, University of Newcastle Upon Tyne, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.363860.
Full text
41
Stickler, Patrick Bickford. "An investigation of mechanical behavior and failure mechanisms of composite T-joints with transverse stitching /." Thesis, Connect to this title online; UW restricted, 2001. http://hdl.handle.net/1773/7058.
Full text
42
Lindmark, Terese. "Welding parameter window for Tandem gas-shielded metal arc welding and fatigue in welded T-joints." Thesis, University West, Department of Technology, Mathematics and Computer Science, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-828.
Full text
43
Jonsson, Björn. "A digital image correlation method for detection of fatigue cracks in non-load carrying T-joints." Thesis, KTH, Lättkonstruktioner, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-234905.
Full textAbstract:
In dynamical loaded welded structures fatigue life is often a limiting factor. Common practise is to reduce nominal stress by increased material thickness which leads to oversized, heavy structures. Those practises are replaced by improvement of production and designingtechniques to utilize better properties of high strength steels.When improving for example quality of welds, issues can occur that standards today did not consider and new test methods can be valuable.In this thesis a method for crack detection in non-load carrying T-joints have been tested. Specimens are made from 6mm Strenx 960MC high strength steel. DIC-analyses is made on frames captured be a high-speed camera during fatigue testing. Hypothesis is that crackpropagation starts when relative strain is higher than 10% per 10 000 cycles.Validation of the method is done by beachmarks from variable stress range during the fatigue test. With the same occurrence as framesets for DIC-analyse. Number of beachmarks agree well with the segment when relative strain indicates crackpropagation in a point at the weld toe.Svetsade konstruktioner under dynamisk belastning blir utmattningshållfastheten ofta en begränsande faktor. Praxis har varit att öka materialtjockleken för att minska nominella spänningen, vilket fungerar bra. Användning av höghållfasthetsstål som tillåter slankarekonstruktioner och viktminskningspotential är det tillvägagångssättet inte aktuellt.Ökad kontroll av svetskvalitet i kombination med kunskap om vilka defekter som påverkar utmattningslivslängden ger möjligheter till viktoptimering. I detta examensarbete har en metod för sprickdetektering under utmattningstest av ickelastöverförande T-förband testats. Provstavar tillverkade av 6mm Strenx 960MC stål. DIC analys genomfördes på bildrutor inspelade av en höghastighetskamera med hypotesen att sprickpropagering detekteras vid 10% relativ töjningsökning per 10 000 cykler.Validering utförs med hjälp av ”beachmarks” från varierande spänningsnivåer under utmattningstestet. Bildsekvensenerna som fångas med höghastighetskameran sammanfaller med slutet på ena spänningsnivån. Antalet ”Beachmarks” visar en sprickfront på ca 200 300μm vid 10% relativ töjning.
44
Boone, George L. (George Leeford). "Analysis and results of the Lazy-L tests for the strength and fracture behavior of welded T-joints." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/38164.
Full textAbstract:
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1996, and Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1996.Includes bibliographical references (leaves 75-76).
by George L. Boone, III.
M.S.
45
Pine, T. "Weight reduction in automotive structural components : an investigation into the torsional properties of steel box sections and T-joints." Thesis, Swansea University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.638535.
Full textAbstract:
Weight reduction of the automotive structure can be enhanced by using continuous joining techniques as a means of assembly. Continuous joints increase structural rigidity and thereby overcome the loss in stiffness associated with the higher strength but thinner steels proposed for use by the automotive industry. The comparison of continuously joined structures with conventionally joined (spot welded) structures will help to determine the potential weight reduction of the automotive structure. The effects of joining technique, sheet thickness, steel strength, section area, section design and level of end constraint on the torsional properties of box sections were determined experimentally using factorial design techniques. The joining techniques investigated included adhesive bonding, weldbonding, laser welding and spot welding. Finite element models were developed using ANSYS and ABAQUS and were used to extend the scope of the test programme. T-joints, comprised of two box sections jointed at right angles, were tested experimentally using factorial design techniques, and were also analysed numerically. Joining technique, sheet thickness and section area had the most influence on box section torsional stiffness. A 44% and 10% weight reduction was estimated through downgauging and area reduction, respectively, in conjunction with the substitution of spot welding with adhesive bonding. Joint eccentricity was also identified as a factor which influenced the torsional stiffness of box sections and could also be related to weight reduction. The effect of joint eccentricity at the connection of T-joints was shown to have a major effect on the torsional stiffness and strength of T-joints. A numerical comparison between a T shaped component from a BIW with a regular T-joint was conducted. The results confirmed the validity of using simplified test pieces to represent more complex components.
46
Dalcin, Rafael Luciano. "Efeitos da energia de soldagem e consumíveis sobre a resistência à flexão de juntas "T" soldadas em perfis tubulares." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2016. http://hdl.handle.net/10183/141104.
Full textAbstract:
O uso de aços de alta resistência mecânica vem crescendo significativamente, principalmente em situações onde é necessário um material com grande limite elástico para a conformação a frio e boa soldabilidade. Nessas aplicações, a elevada resistência reduz o peso e/ou aumenta a carga que pode ser suportada pelas estruturas produzidas. A introdução dos aços fabricados por processamento termomecânico controlado (TMCP) demandou maiores propriedades mecânicas e metalúrgicas das juntas soldadas sobre eles produzidas. Em função desses fatores, a energia de soldagem é estritamente limitada, e para evitar uma eventual redução da resistência mecânica da zona afetada pelo calor (ZAC), é necessário testar os procedimentos de soldagem próximos daqueles que serão usados na estrutura real. O objetivo deste estudo é obter dados detalhados referentes à eficiência mecânica de juntas soldadas por MAG e com diferentes energias, sobre perfis tubulares quadrados em aço TMCP, formando um conjunto soldado coluna/viga. Seis energias de soldagem e dois metais de adição foram utilizados (AWS ER80S-G e AWS ER120S-G), o primeiro somente com as soldas posicionadas em todo o contorno do perfil, e o segundo com soldas em todo o contorno, transversais e longitudinais em relação à direção de aplicação da carga. Vinte e quatro estruturas foram soldadas, instrumentadas e submetidas à flexão. Comparando as juntas soldadas com mesma energia, observou-se maior resistência à flexão nas soldas longitudinais e em todo contorno, e valores inferiores para soldas transversais. Além disso, pôde ser constatado que 1,2 kJ/mm de energia de soldagem deu os melhores resultados para as juntas soldadas com ambos os consumíveis, uma vez que até esse valor a área da seção resistente das juntas soldadas aumentou significativamente. O uso de energias mais elevadas não foi eficaz para aumentar a resistência à flexão das juntas soldadas ora investigadas, pois o efeito da energia de soldagem sobre a redução da dureza e, consequentemente, resistência mecânica da ZAC, aparentemente se sobrepõe ao aumento da área da seção resistente da junta soldada.The use of high strength steels is growing significantly, especially in situations where it is necessary a material with high strength for cold forming and good weldability. In these applications, the high strength decreases the weight and/or increases the load that can be supported by the structures produced. The introduction of steels made by thermomechanical controlled processing (TMCP) demanded higher mechanical and metallurgical properties of the welded joints produced on them. Given these factors, the heat input is strictly limited, and to avoid any reduction in the mechanical strength of the heat affected zone (HAZ), it is required to test welding procedures close to those that will be used in the actual structure. The aim of this study is to obtain detailed data on the mechanical efficiency of welded joints with GMAW and different heat inputs, on square tubular profiles in TMCP steel, disposed as a column/beam weldment. Six different heat inputs and two filler metals were used (AWS ER80S-G and AWS ER120S-G), the first one with the welds located around the profile contour, and the second one with welds all around the profile, transverse and longitudinal to the axis of the weld bead. Twenty-four welded structures were instrumented and subjected to bending. Comparing the welded joints with the same heat input, it can be noticed that higher bending strength is obtained from all-around contour and longitudinal welds, and lower values for the transverse welds. Moreover, it could be seen of 1.2 kJ/mm heat input gave optimum results to the welded joints with both consumables, since up to this value the area of the resistant section of welded joints increased significantly. The use of higher heat inputs was not effective to increase the bending strength of the welded joints herein investigated, since the effect of heat input on the reduction of the hardness and, consequently, mechanical strength of the HAZ, apparently overrides the increase in the area of the resistant section of the welded joint.
47
Bayraktar, Funda Seniz [Verfasser], and Norbert [Akademischer Betreuer] Huber. "Analysis of residual stress and fatigue crack propagation behaviour in laser welded aerospace Aluminium T-joints / Funda Seniz Bayraktar. Betreuer: Norbert Huber." Hamburg-Harburg : Universitätsbibliothek der Technischen Universität Hamburg-Harburg, 2012. http://d-nb.info/1048542289/34.
Full text
48
Bayraktar, Funda Seniz Verfasser], and Norbert [Akademischer Betreuer] [Huber. "Analysis of residual stress and fatigue crack propagation behaviour in laser welded aerospace Aluminium T-joints / Funda Seniz Bayraktar. Betreuer: Norbert Huber." Hamburg-Harburg : Universitätsbibliothek der Technischen Universität Hamburg-Harburg, 2012. http://nbn-resolving.de/urn:nbn:de:gbv:830-tubdok-11318.
Full text
49
Ito, Yoshinaga. "γδ T cells are predominant source of IL-17 in the affected joints of collagen-induced arthritis, but not in rheumatoid arthritis." Kyoto University, 2009. http://hdl.handle.net/2433/126448.
Full text
50
Desjardins, Nicholas. "On Applying Methods for Graph-TSP to Metric TSP." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/35613.
Full textAbstract:
The Metric Travelling Salesman Problem, henceforth metric TSP, is a fundamental problem in combinatorial optimization which consists of finding a minimum cost Hamiltonian cycle (also called a TSP tour) in a weighted complete graph in which the costs are metric. Metric TSP is known to belong to a class of problems called NP-hard even in the special case of graph-TSP, where the metric costs are based on a given graph. Thus, it is highly unlikely that efficient methods exist for solving large instances of these problems exactly.
In this thesis, we develop a new heuristic for metric TSP based on extending ideas successfully used by Mömke and Svensson for the special case of graph-TSP to the more general case of metric TSP. We demonstrate the efficiency and usefulness of our heuristic through empirical testing.
Additionally, we turn our attention to graph-TSP. For this special case of metric TSP, there has been much recent progress with regards to improvements on the cost of the solutions. We find the exact value of the ratio between the cost of the optimal TSP tour and the cost of the optimal subtour linear programming relaxation for small instances of graph-TSP, which was previously unknown. We also provide a simplified algorithm for special graph-TSP instances based on the subtour linear programming relaxation.