Log in

Relevant bibliographies by topics / Welder / Dissertations / Theses

To see the other types of publications on this topic, follow the link: Welder.

Dissertations / Theses on the topic 'Welder'

Author: Grafiati

Published: 4 June 2021

Last updated: 17 February 2022

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Consult the top 50 dissertations / theses for your research on the topic 'Welder.'

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

Davies, Edward. "Development of a hand-held multicell inverter-based ultrasonic plastic welder." Thesis, Cape Peninsula University of Technology, 2009. http://hdl.handle.net/20.500.11838/1093.

Full text

Abstract:

Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology, 2009<br>This thesis presents the design and development of a multicell inverter for ultrasonic plastic welding applications and other ultrasonic applications. An overview of the main multilevel topologies is given, but this research focuses on the multicelll inverter, because of its capacitor voltage balancing properties. Loading effects of various plastic materials to an ultrasonic plastic welding tool are provided in this thesis. A simple method to create an approximate electrical equivalent circuit of the ultrasonic welding tool, using an impedance analyser, loaded with different plastics is discussed and illustrated. Experimental results of the four-level multicell inverter driving a resistive load and an ultrasonic transducer tool are presented in this thesis. These results provide proof that the multicell inverter topology is capable of driving a non-linear load. The inverter was tested with the ultrasonic load as an ultrasonic plastic welder and an ultrasonic drill. The welding joints on the plastic samples are also evaluated in order to evaluate whether or not this solution is suitable for plastic welding. The ultrasonic drilling results are also shown in this thesis. It is further illustrated that the ultrasonic tool and power supply combination may be used in other ultrasonic applications.

APA, Harvard, Vancouver, ISO, and other styles

2

Welder, Rachael Mae. "Preservice Elementary Teachers' Mathematical Content Knowledge of Prerequisite Algebra Concepts." Thesis, Montana State University, 2007. http://etd.lib.montana.edu/etd/2007/welder/WelderR0507.pdf.

Full text

Abstract:

Research illustrating that student achievement is affected by teachers' knowledge advocates for K-8 teachers to be knowledgeable regarding prerequisite algebra concepts: (1) numbers (numerical operations), (2) ratios/proportions, (3) the order of operations, (4) equality, (5) patterning, (6) algebraic symbolism (including letter usage), (7) algebraic equations, (8) functions, and (9) graphing. The theoretical framework for the knowledge for teaching mathematics built for this study suggests that the mathematical content knowledge needed for teaching consists of specialized content knowledge in addition to common content knowledge. Specialized mathematical content knowledge extends beyond solving mathematical problems to encompass how and why mathematical procedures work and an awareness of structuring and representing mathematical content for learners. The effects of an undergraduate mathematics content course for elementary education students on preservice teachers' common and specialized content knowledge of prerequisite algebra concepts was investigated, using a pre-experimental one-group pretest-posttest design. A quantitative, 51-item, multiple-choice instrument, developed specifically to measure both types of content knowledge with respect to prerequisite algebra concepts, was constructed from the Learning Mathematics for Teaching Project's Content Knowledge for Teaching Mathematics Measures question bank. This instrument was administered to all students enrolled in Mathematics for Elementary Teachers I (n = 48), at Montana State University, during the fall semester of 2006. Matched pairs t-tests, comparing pretest and posttest scores within the single sample, show significant gains (p = .000) in both common and specialized content knowledge and in all tested aspects of prerequisite algebra knowledge (numbers and equations/functions). Results also suggest a significant correlation (r = .716, p = .000) between preservice teachers' common and specialized content knowledge. Lastly, a oneparameter linear model was constructed to predict the number of participants to incorrectly answer each item, based on item difficulty. Items missed by notably more or less students than predicted were identified and analyzed. The one item students performed better than expected on addresses common content knowledge regarding a linear graph. The set of troublesome items address both common and specialized content knowledge of reading, writing, and representing functions in a variety of contexts and using ratios to write and solve proportions.

APA, Harvard, Vancouver, ISO, and other styles

3

Palmer, Benjamin L. "Effect of welder group size on individual respiratory exposures to welding fumes." Oklahoma City : [s.n.], 2010.

Find full text

APA, Harvard, Vancouver, ISO, and other styles

4

Liu, Yukang. "Virtualized Welding Based Learning of Human Welder Behaviors for Intelligent Robotic Welding." UKnowledge, 2014. http://uknowledge.uky.edu/ece_etds/51.

Full text

Abstract:

Combining human welder (with intelligence and sensing versatility) and automated welding robots (with precision and consistency) can lead to next generation intelligent welding systems. In this dissertation intelligent welding robots are developed by process modeling / control method and learning the human welder behavior. Weld penetration and 3D weld pool surface are first accurately controlled for an automated Gas Tungsten Arc Welding (GTAW) machine. Closed-form model predictive control (MPC) algorithm is derived for real-time welding applications. Skilled welder response to 3D weld pool surface by adjusting the welding current is then modeled using Adaptive Neuro-Fuzzy Inference System (ANFIS), and compared to the novice welder. Automated welding experiments confirm the effectiveness of the proposed human response model. A virtualized welding system is then developed that enables transferring the human knowledge into a welding robot. The learning of human welder movement (i.e., welding speed) is first realized with Virtual Reality (VR) enhancement using iterative K-means based local ANFIS modeling. As a separate effort, the learning is performed without VR enhancement utilizing a fuzzy classifier to rank the data and only preserve the high ranking “correct” response. The trained supervised ANFIS model is transferred to the welding robot and the performance of the controller is examined. A fuzzy weighting based data fusion approach to combine multiple machine and human intelligent models is proposed. The data fusion model can outperform individual machine-based control algorithm and welder intelligence-based models (with and without VR enhancement). Finally a data-driven approach is proposed to model human welder adjustments in 3D (including welding speed, arc length, and torch orientations). Teleoperated training experiments are conducted in which a human welder tries to adjust the torch movements in 3D based on his observation on the real-time weld pool image feedback. The data is off-line rated by the welder and a welder rating system is synthesized. ANFIS model is then proposed to correlate the 3D weld pool characteristic parameters and welder’s torch movements. A foundation is thus established to rapidly extract human intelligence and transfer such intelligence into welding robots.

APA, Harvard, Vancouver, ISO, and other styles

5

Zackiewicz, Curt Stephen. "DC-DC Power Converter Design for a Portable Affordable Welder System (PAWS)." Wright State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=wright1300807818.

Full text

APA, Harvard, Vancouver, ISO, and other styles

6

Stegelman, Michael S. "Development of a cost effective organizational model for the shipbuilding welder labor workforce." Thesis, Monterey, California : Naval Postgraduate School, 2009. http://edocs.nps.edu/npspubs/scholarly/theses/2009/Sep/09Sep%5FStegelman.pdf.

Full text

Abstract:

Thesis (M.S. in Systems Engineering Management)--Naval Postgraduate School, September 2009.<br>Thesis Advisor(s): Osmundson, John. "September 2009." Description based on title screen as viewed on November 6, 2009. Author(s) subject terms: Manpower, Marine Welder, Organizational Structure, Labor Workforce Development, Requirements Management, Marine Labor Crafts, Trade Union, Gap Analysis Includes bibliographical references (p. 73-76). Also available in print.

APA, Harvard, Vancouver, ISO, and other styles

7

Yu, Rui. "A REDUNDANT MONITORING SYSTEM FOR HUMAN WELDER OPERATION USING IMU AND VISION SENSORS." UKnowledge, 2018. https://uknowledge.uky.edu/ece_etds/128.

Full text

Abstract:

In manual control, the welding gun’s moving speed can significantly influence the welding results and critical welding operations usually require welders to concentrate consistently in order to react rapidly and accurately. However, human welders always have some habitual action which can have some subtle influence the welding process. It takes countless hours to train an experienced human welder. Using vision and IMU sensor will be able to set up a system and allow the worker got more accurate visual feedback like an experienced worker. The problem is that monitor and measuring of the control process not always easy under a complex working environment like welding. In this thesis, a new method is developed that use two different methods to compensate each other to obtain accurate monitoring results. Vision sensor and IMU sensor both developed to obtain the accurate data from the control process in real-time but don’t influence other. Although both vision and IMU sensor has their own limits, they also have their own advantage which can contribute to the measuring system.

APA, Harvard, Vancouver, ISO, and other styles

8

White, Steven A. "Impact of Visualization Augmentation on Welder Training| A Study with the Simulated MIG Lab." Thesis, University of Louisiana at Lafayette, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=3590087.

Full text

Abstract:

<p> This works outlines the creation of a fully immersive real time simulation of the Metal Inert Gas Welding technique. It outlines the creation, development and trials associated with creating a unique GPU based physical simulation and visualizations associated with the simulated environment. A trial is conducted among various students and technical personnel with the simulator to investigate the concepts of learning transfer through simulation augmentation. The results are positive towards low-road transfer and additionally outline future studies in the fields.</p>

APA, Harvard, Vancouver, ISO, and other styles

9

Zelený, Miroslav. "Provoz distribučních sítí s odporovými svářečkami." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2012. http://www.nusl.cz/ntk/nusl-219391.

Full text

Abstract:

This Diploma thesis deals with assessment of the influence of two fundamental types of resistance welders operation on chosen power quality parameters at the point of common coupling (PCC) of the power network. The assessed parameters of power quality are the total harmonic distortion of the supply voltage, asymmetry of the supply voltage and the level of short term flicker at the point of common coupling. The assessment is based on the comparison of the results of computer simulations done in PSCad 4.2.0 with the requirements of technical standards. The outcome of this thesis is the determination of allowable limits for physical and operation parameters for the general arrangement of a power distribution network and a resistance welder that should guarantee the power quality compliance.

APA, Harvard, Vancouver, ISO, and other styles

10

Dansie, Ty Samual. "Simulation of the Inertia Friction Welding Process Using a Subscale Specimen and a Friction Stir Welder." BYU ScholarsArchive, 2018. https://scholarsarchive.byu.edu/etd/6749.

Full text

Abstract:

This study develops a method to simulate a full-scale inertia friction weld with a sub-scale specimen and modifies a direct drive friction stir welder to perform the welding process. A torque meter is fabricated for the FSW machine to measure weld torque. Machine controls are modified to enable a force control during the IFW process. An equation is created to measure weld upset due to deflection of the FSW machine. Data obtained from a full-scale inertia friction weld are altered to account for the geometrical differences between the sub-scale and full-scale specimens. The IFW are simulated with the sub-scale specimen while controlling spindle RPM and matching weld power or weld RPM. The force used to perform friction welding is scaled to different values accounting for specimen size to determine the effects on output parameters including: HAZ, upset, RPM, torque, power and energy of the weld. Increasing force has positive effects to upset, torque, power and energy of the welds, while reducing the size of the HAZ.

APA, Harvard, Vancouver, ISO, and other styles

11

Panchártková, Denisa. "Uplatnění lean techniky pro zlepšení procesu vyhledávání a přijímání zaměstnanců na úrovni modrých límečků." Master's thesis, Vysoká škola ekonomická v Praze, 2014. http://www.nusl.cz/ntk/nusl-201710.

Full text

Abstract:

The aim of the thesis is improvement of the recruitment process for the position of welder in a particular company so that the plan to hire 45 new welders would be filled until the end of 2015. As part of the process another opportunity to improve was found and defined. This secondary issue is high fluctuation of welders. Secondary targets of the thesis include mapping, measuring and analysis of the current state of new workers recruitment and also positive motivation of current welders, which create the basis for proposed changes that were later implemented. In the last step the impacts of these changes are controlled and summed up. The whole process follows the DMAIC method steps. During the real project solution tools like Lean management, SIPOC, Flowchart and Ishikawa diagram, first pass yield, A3 report and Benchmarking were used. Above mentioned methodological tools are all described in the practical part of the thesis. In conclusion, it was found out that suggested and implemented amendments improved the recruitment process by 12 percentage points. Fluctuation, the second drawback, is however not possible to measure yet as the impact of the changes will be expected to show within 1 year. Although there was a significant improvement of the whole processes, the plan was not met up to the last day in October 2015. Out of the 45 planned positions, 37 welders in total were casted.

APA, Harvard, Vancouver, ISO, and other styles

12

Zhang, Weijie. "Machine-human Cooperative Control of Welding Process." UKnowledge, 2014. http://uknowledge.uky.edu/ece_etds/45.

Full text

Abstract:

An innovative auxiliary control system is developed to cooperate with an unskilled welder in a manual GTAW in order to obtain a consistent welding performance. In the proposed system, a novel mobile sensing system is developed to non-intrusively monitor a manual GTAW by measuring three-dimensional (3D) weld pool surface. Specifically, a miniature structured-light laser amounted on torch projects a dot matrix pattern on weld pool surface during the process; Reflected by the weld pool surface, the laser pattern is intercepted by and imaged on the helmet glass, and recorded by a compact camera on it. Deformed reflection pattern contains the geometry information of weld pool, thus is utilized to reconstruct its $3$D surface. An innovative image processing algorithm and a reconstruction scheme have been developed for (3D) reconstruction. The real-time spatial relations of the torch and the helmet is formulated during welding. Two miniature wireless inertial measurement units (WIMU) are mounted on the torch and the helmet, respectively, to detect their rotation rates and accelerations. A quaternion based unscented Kalman filter (UKF) has been designed to estimate the helmet/torch orientations based on the data from the WIMUs. The distance between the torch and the helmet is measured using an extra structure-light low power laser pattern. Furthermore, human welder's behavior in welding performance has been studied, e.g., a welder`s adjustments on welding current were modeled as response to characteristic parameters of the three-dimensional weld pool surface. This response model as a controller is implemented both automatic and manual gas tungsten arc welding process to maintain a consistent full penetration.

APA, Harvard, Vancouver, ISO, and other styles

13

Nóbrega, Rita de Lima. "Mulheres de ferro: a dupla jornada das operárias soldadoras na cidade do Rio Grande." Universidade Catolica de Pelotas, 2014. http://tede.ucpel.edu.br:8080/jspui/handle/tede/352.

Full text

Abstract:

Made available in DSpace on 2016-03-22T17:27:28Z (GMT). No. of bitstreams: 1 rita nobrega.pdf: 2472570 bytes, checksum: 044be3be25cfb451f3423e176744d9a6 (MD5) Previous issue date: 2014-03-19<br>This quantitative research deals with the representation of welder women in Rio Grande city. The corpus consists of the welder women´s interviews, employed in the Ecovix/Engevix Construções Oceânicas, who are nowadays working in the Naval Cluster of the city. This thesis is based on the Critical Discourse Analysis (CDA) according to Norman Fairclough`s research principles and gender studies, and aims at examining these workers profiles, both professional and domestic, throughout the analysis of their discourse, understood as a result of these women`s social practice structured according to their ideologies and social relationship. From such a perspective, the double journey and the enrollment of these women in that profession, up to now a man´s job only, are the issues under discussion in this thesis. It leads us to investigate social-cultural issues that are present in the social imaginary such as the fact of associating the idea that women are subordinated to men, and the intellectual incompetence of production that affects the female figure. Although women have achieved many victories, and shaped a new sexual division of work, these prejudiced and hegemonic discourses are still found in many cultural artefacts and in society. This fact happens because society, still patriarchal, considers gender linked to biological issues and not to the theoretical view that places it within cultural issues. CDA is an interdisciplinary theory that proposes a tridimensional analysis of discourse that comprises text, discourse practice and social practice. Among the several possibilities of choosing among the categories of CDA in order to analyze the corpus, in this thesis, the selected ones are: vocabulary, intertextuality, politeness, and ethos.<br>Esta pesquisa de cunho qualitativo disserta a respeito da representação das mulheres soldadoras da cidade do Rio Grande. Tem como corpus as respostas das entrevistas realizadas com as soldadoras da empresa Ecovix/Engevix Construções Oceânicas, atuantes no Polo Naval da cidade. À luz da Análise Crítica do Discurso (ACD), segundo Norman Fairclough, e dos estudos de gênero, objetiva verificar o perfil (profissional e doméstico) dessas trabalhadoras por meio do discurso, no entender de que este advém de uma prática social, constituída em meio a ideologias e relações sociais. Nesse viés, a dupla jornada de trabalho e a entrada das mulheres nessa profissão, até então masculina, são os fatos problematizados aqui. A dissertação possibilita refletir acerca de algumas questões socioculturais presentes no imaginário social, como o fato de relacionar as mulheres com a subordinação ao masculino e a incapacidade produtiva e intelectual feminina. Apesar de as mulheres terem conseguido muitas vitórias, configurando uma nova divisão sexual do trabalho, esses discursos preconceituosos e hegemônicos ainda são veiculados nos mais variados artefatos culturais e na sociedade em geral. Isso ocorre porque a sociedade, ainda patriarcal, vê o gênero ligado às questões biológicas e não sob a vertente teórica que o remete às questões culturais. A ACD é uma teoria interdisciplinar que propõe uma análise tridimensional do discurso, a qual engloba o texto, a prática discursiva e a prática social. Dentre as várias possibilidades de categorização do corpus, neste trabalho, são elencadas o vocabulário, a intertextualidade, a polidez e o ethos

APA, Harvard, Vancouver, ISO, and other styles

14

Dolejský, Tomáš. "Porovnání nákladů na svařování a Virtual Welding." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-231042.

Full text

Abstract:

The thesis deals with a potential application of welding simulators in basic courses of welding held in welding schools. The first section briefly describes the welding simulators in the global market. There is a detailed description and the control of the welding simulator Virtual Welding, a description of core courses of welding and the necessary welding technology in the following section. Experiments with a welding simulator are carried out in the last section and also their evaluation, comparison and summary of costs.

APA, Harvard, Vancouver, ISO, and other styles

15

Zobač, Martin. "Řízení a diagnostika elektronového svazku pro pokročilé technologie." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2010. http://www.nusl.cz/ntk/nusl-233899.

Full text

Abstract:

The thesis deals with problems of control and diagnostics of electron beam technological devices which use electron beam for localised intensive heating of a material. A brief description of the electron beam welder MEBW-60/2 is included; the author has participated on its development and implementation. Main topics are the analysis of deflection system properties and the measurement of current distribution of the beam (so-called beam profiles). Geometrical aberrations, hysteresis, stability and dynamics of a single-stage magnetic x-y deflection system are described. Suitable measurement procedures and correction methods are introduced. Methods of transverse and longitudinal beam profile acquisition is presented using successive sampling of the local current density of the beam by a modified Faraday cup. The data processing and evaluation of characteristic beam parameters are shown. The presented methods were verified by fourteen experiments using the electron beam welder. The methods have proven to be useful in practical evaluation of the device properties.

APA, Harvard, Vancouver, ISO, and other styles

16

Hrdina, Adam. "Bateriová oblouková svářečka." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2017. http://www.nusl.cz/ntk/nusl-318187.

Full text

Abstract:

This master’s thesis deals with the design and fabrication of DC arc welder supplied from its own rechargeable battery. Battery cells’ type is LiFePO4 which can provide high currents even at relatively low capacity. The BMS circuits are designed within the battery. Major power part of the welder is a step-down converter with synchronously switching low transistors at the position of free-wheel diode. The converter operates at 100 kHz frequency. The current of the battery welder can be regulated in the range from 0 to 120 A.

APA, Harvard, Vancouver, ISO, and other styles

17

LeBouton, Marc Christopher 1964. "WELDED-WELDED FRAMING ANGLE CONNECTIONS." Thesis, The University of Arizona, 1987. http://hdl.handle.net/10150/276470.

Full text

Abstract:

Results of tension and compression tests on angle segments are used to generate moment-rotation curves for welded-welded double framing angle connections. The beam line concept is then used to determine the connection moments for connection depths of 18 to 32 inches. With the connection moments known, the two welds, denoted as Weld A and Weld B in the AISC Manual Table IV are evaluated. Because the analytical model used to generate the weld sized published in the AISC Manual and analytical model used in this research differ, it was found that the capacities of the connection designs in the AISC Manual for Weld B have factors of safety ranging from 2.5 to 3.0. Design aids are included which give the connection moments for a variety of designs as a function of the length to depth ratio of the beam for the case of uniform loading.

APA, Harvard, Vancouver, ISO, and other styles

18

Low, Choon Ann Kenneth. "Measurement of elevated temperature creep strains in cross-weld specimens using the grid method." Thesis, University of Nottingham, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.368969.

Full text

APA, Harvard, Vancouver, ISO, and other styles

19

EKLUND, FREDRIK. "Design Study of Welded Beam Bracket According to Stress Concentrations in the Weld." Thesis, KTH, Skolan för industriell teknik och management (ITM), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-300146.

Full text

Abstract:

In a bus chassis, welded connections are often preferred to other fastening techniques due to low cost and broad competence among suppliers but are usually the weakest parts due to fatigue life. Evaluation of welds is often costly in time and competence. Long iteration times are often leaving welded designs unoptimized and poorly understood by designers and engineers. The goal of this thesis is to gather knowledge about a plug-welded bracket commonly found welded to beams in bus chassis and body, aiding the design and dimensioning of such brackets. A factorial design study was performed using FEM analysis with the “Effective notch method,” revealing the effects of seven different design parameters on the stresses in the weld. A theory to analytically calculate the profile of the bracket is presented. The theory is taking the beam’s second moment of area and the bending moment into consideration, essentially tuning the bracket’s stiffness to the beam and the load situation. An improved bracket is presented, analyzed, and compared to the design study. The results show how stresses in the weld are affected by the stiffness of the bend in the bracket, the location of bolts (or other fastening technique) and the plug weld dimensions. When the weld is made to run longer along the beam, the importance of adjusting the stiffness in the bracket increases in order to balance the load throughout the whole weld.<br>Svetsade fästelement är ofta att föredra i ett busschassi över andra tekniker av kostnadsskäl och att en bred kompetens finns inom svets hos många underleverantörer. Men på grund av utmattning är ofta svetsade infästningar den svagaste punkten i ett chassi. Utvärdering av svetsar är kostsamt i tid och kompetens. Långa iterationstider i svetsutvärderingar lämnar ofta svetsen ooptimerad och undermåligt förstådd av designers och ingenjörer. Målet med detta arbete är att samla kunskap runt ett pluggsvetsat fästelement som ofta förekommer i busschassier och busskarosser, för att underlätta design och dimensionering av dessa fästelement. En faktoriell designstudie var utförd med FEM analys enligt ”Effective Notch” metoden för att undersöka effekten från sju olika designparametrar på spänningskoncentrationerna i svetsen. En teori för att analytiskt beräkna profilen på fästelementet presenteras. Teorin tar balkens böjtröghetsmoment och böjmoment med i beräkningen för att optimera fästelementets styvhet till balken och lastsituationen. Ett förbättrat fästelement är presenterat, analyserat och jämförd med designstudien. Resultaten visar hur spänningarna i svetsen påverkas av styvheten i den böjda delen av fästelementet, placeringen av bultar (eller annan infästningsteknik) och dimensioner på ”svetspluggen.” När svetsen är går längre längs med balken blir fästelementets styvhet allt viktigare för att kunna balansera lasten igenom det svetsade området.

APA, Harvard, Vancouver, ISO, and other styles

20

Kriedel, Norbert. "Lange Wellen der wirtschaftlichen Entwicklung : empirische Analysen, bestehende Erklärungsmodelle und Neumodellierung /." Münster : LIT-Verl, 2005. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=014165837&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.

Full text

APA, Harvard, Vancouver, ISO, and other styles

21

Reed, Jordan Derek. "Ultrasonic Processing of Aluminum 2139 and 7050." Thesis, University of North Texas, 2018. https://digital.library.unt.edu/ark:/67531/metadc1248496/.

Full text

Abstract:

Acoustics is the study of all sound waves, with ultrasound classified as those frequencies above 20,000 Hz. Currently, ultrasound is being used in many industries for a variety of purposes such as ultrasonic imaging, ultrasonic assisted friction stir welding, and ultrasonic spot welding. Despite these uses, the effects of ultrasound on phase stability and resultant mechanical properties has been minimally analyzed. Here we study the impact waves play in ultrasonic welding and design an apparatus to maximize waves entering aluminum alloy samples. Aluminum 2139 and 7050 are used because they are precipitation strengthened by metastable phases so temperature change, and the corresponding phase stability, can greatly impact their strength. Results suggest that the ultrasonic welder primarily imposes a localized temperature spike due to friction, averaging over 200°C in a few seconds, which generally lowers the Vickers hardness due to coarsening or even dissolution of strengthening precipitates. Conversely, the new design increases the Vickers hardness by up to 30% over the initial hardness of approximately 63HV for aluminum 2139 and 83HV for aluminum 7050, respectively, while only increasing the temperature by an average of approximately 10°C. This new design was unable to achieve peak hardness, but the strengthening it achieved in two minutes was equivalent to one month of natural aging. If this system was able to be fine-tuned, it could serve as a quick strengthening process for recently weakened aluminum alloys, such as after friction stir welding.

APA, Harvard, Vancouver, ISO, and other styles

22

Říčan, Daniel. "Struktura a vlastnosti průvaru oceli AMS 5659 vytvořeného elektronovým svazkem." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-230799.

Full text

Abstract:

This master thesis deals with the electron beam welding of the AMS 5659 steel used in industry for special hydraulic cylinders (Fig. 1). A theoretical analysis of electron beam welding and analysis of the influence of selected welding parameters on penetration characteristics are in the first part of the thesis. The second part contains an evaluation of the implemented experimental penetrations on samples of the steel in the hardened condition H1025 and after solution heat. It was also done a properties assessment of the same samples that were been hardened again. The light microscopy (SM), the scanning electron microscopy (SEM) and the measurement method of hardness according to Vickers were used for evaluation and comparison of the steel properties in the region of penetration and the heat affected zones properties.

APA, Harvard, Vancouver, ISO, and other styles

23

Lai, Yuk Fai Willy. "Buckling strength of welded and non-welded aluminium members." Thesis, University of Sheffield, 1989. http://etheses.whiterose.ac.uk/14699/.

Full text

Abstract:

High strength aluminium alloys when welded suffer a local loss of strength due to heat-affected zone (HAZ) effects. The influence of such localised strength loss on structural behaviour of columns, beams and beam-columns is studied using numerical technique. Two programs INSTAF and BIAXIAL, previously developed for the use of steel structures, have been modified to incorporate the special features of the aluminium problem. The general inplane behaviour of aluminium frames or members is studied by using program INSTAF. The general 3-D behaviour of aluminium members is simulated by the program BIAXIAL. Attention is given to the representation of the nonlinear stress-strain behaviour of aluminium, in particular, its representation in a form suitable for incorporation into numerical processes. Results are presented for a wide range of problems to illustrate the severity of the HAZ effect on the load carrying capacity of structural members.

APA, Harvard, Vancouver, ISO, and other styles

24

Orloff, Kenneth L. "An Experimental Study of the Influence of Eccentricity on Shear Lag Effects in Welded Connections." University of Cincinnati / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1491560125351369.

Full text

APA, Harvard, Vancouver, ISO, and other styles

25

García, Gil Antonio Rafael, and Mernissi Oualid El. "Spot welded ENF-Specimen." Thesis, Högskolan i Skövde, Institutionen för ingenjörsvetenskap, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-9465.

Full text

Abstract:

The behaviour of spot welded joints is to be studied in shear mode by using the end notched flexure (ENF) specimen. The specimen counts on several spot welds spaced with the same gap along the entire length except for the notch. Different configurations of the test specimen spacing gap and spot diameter are to be preliminary designed in software PTC-CREO 2.0 in order to obtain accurate results. The results obtained from the software are to be compared with the experimental analysis performed by means of a servo-hydraulic testing machine. Both the virtual and the experimental results will be used to extract the stress-shear displacement relation around the first spot weld which is in contact with the notch, that is, the corresponding cohesive law. In addition, a comparison between adhesive and spot weld behaviours will be carried out by means of analytical equations in order to prove an existing equalisation between each other. Despite assuming several sources of error and after facing some problems related to the experimental work, accurate convergences between experimental and theoretical results were not accomplished in any of the three tests performed in lab. Due to the plastic deformation of the specimens in lab, the cohesive law was possible to be extracted only from the theoretical analysis, but not from the experimental one. In its place, the load-shear displacement was extracted. Some alternatives to solve this issue and to improve the performance of the tests are given at the end of this paper.

APA, Harvard, Vancouver, ISO, and other styles

26

Smallidge, Jeffrey M. "Behavior of bolted beam-to-column T-stub connections under cyclic loading." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/19534.

Full text

APA, Harvard, Vancouver, ISO, and other styles

27

Schrauben, Corey S. "Behavior of full-scale bolted beam-to-column T-stub and clip angle connections under cyclic loading." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/20013.

Full text

APA, Harvard, Vancouver, ISO, and other styles

28

Baum, Kristen Anne. "Feral Africanized honey bee ecology in a coastal prairie landscape." Texas A&M University, 2003. http://hdl.handle.net/1969/150.

Full text

APA, Harvard, Vancouver, ISO, and other styles

29

Stengler, Matthias [Verfasser], Bernhard [Akademischer Betreuer] Weller, and Dieter [Akademischer Betreuer] Fellmann. "Bestandskonforme Weiternutzung von Fabriken / Matthias Stengler. Gutachter: Bernhard Weller ; Dieter Fellmann. Betreuer: Bernhard Weller." Dresden : Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2012. http://d-nb.info/1068442557/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

30

Bona, Melissa Ellen. "The effect of straightening and grinding of welds on track roughness." Queensland University of Technology, 2005. http://eprints.qut.edu.au/16180/.

Full text

Abstract:

Rail is a very expensive component of the railway track. Therefore, research methods extending rail life have great economic importance. During the past thirty years and, particularly during the past ten years there has been an increasing awareness throughout most rail networks in the world of the need to introduce improved design criteria, better construction techniques and higher standard track generally. This implies that quality control at all levels is mandatory if these objectives are to be achieved. With the improved understanding of degradation of track, a more complete comprehension of the costs associated with different operating and infrastructure conditions should also be developed, aiding in the determination of efficient maintenance costs and their contribution to access charges. Track and structures together account for 60% of maintenance costs, with 50% of the total being track. The UIC has done a lot of work on comparative performance indicators, and these show what potential savings much be out there for the taking, just by adopting current best practice. The old wisdom is that it's not enough o do things rights; we have to make sure that we do the right things. These developments have largely resulted from the demand for higher speeds particularly in passenger services and the demand to accept heavier axle loads of freight traffic. Whilst the conventional railway track structure is not likely to change significantly over the next ten years there will be a requirement over that period for better quality track infrastructure. This means less rail surface defects, less internal defects and less wheels irregularities. The presence of rail surface defects generally increases the roughness of the track leading to a poor passenger ride and increased safety risk with freight traffic. In addition, rail surface defects will generally increase the degradation rate of other track components; however, not all defects will produce visible track deterioration. Dynamic impacts produced by the rollingstock running over rail surface defects, such as poor welds, will, over time, create continuous rail defects, loosening of fastenings, abrasion and skewing of sleepers, crushing of ballast and loss of formation geometry. It is only in the recent years that the importance of poor welds in track has been identified. Dips and peaks must be recognised as a severe track irregularity that needs to be addressed and removed. Current maintenance activities have little effect on removing misaligned welds in track and the improvement obtained after the maintenance works is generally short lived. On the other hand, straightening operations have proven to solve the problem and maintain the results following 7 months of traffic. As part of this project, a six kilometre test section was selected on the Mt Isa Line and all welds located in this region were monitored for over 9 months to increase the understanding of the effect of individual maintenance activities on the track roughness. Three 2km Divisions were established; each Division had different maintenance activities and levels of intervention completed over the duration of the project. Over 15,000 readings were recorded and analysed. The following conclusions were drawn. The effect of cycle tamping was clearly identified when comparing the means of weld located in Division 1, 2 to the mean of welds in Division 3. Cycle tamping showed to have a significant positive effect on the dipped welds geometry and an increase in severity of peaked welds prior to their correction. Straightening operations completed in Division 1 and 2 reduced the overall mean of weld misalignments. These Divisions were subjected to different levels of straightening intervention however they produced similar results. Division 1 all dips were straightened and Division 2 only dips &gt0.3mm were straightened. This means that no additional benefit, in terms of overall misalignment of welds, can be gained when straightening operations target dips with a misalignment smaller than 0.3mm. Cycle grinding proved to have little effect on the removal of both dips and peaks. In fact, due to the configuration of the grinding machine, grinding operation produced a slight worsening of the dips misalignments and only a minor improvement of peaks. Although long term monitoring of the site may show minor variations in weld geometry performance, after approximately 3.9 Mgt of traffic the mean of dipped welds in Division 1 and 2 appeared to remain unaltered, as Division 3 showed a minor worsening. Furthermore, the mean of peaked welds in Division 1 and 2 appeared to remain unaltered, as Division 3 showed a minor worsening.

APA, Harvard, Vancouver, ISO, and other styles

31

Rayner, Glen. "Creep of welded branched pipes." Thesis, University of Nottingham, 2004. http://eprints.nottingham.ac.uk/11660/.

Full text

Abstract:

Creep failure of welds in high-temperature power plant steam piping systems is known to be a potential cause of plant failure. Creep behaviour of plain pipes with circumferential welds and cross-weld specimens have received fairly extensive attention. However, research into the creep behaviour of welded thick-walled branched steam pipes has received less attention. Consequently, this thesis addresses improving the understanding of the creep behaviour for this type of geometry. Numerical and analytical methods are used to assess the creep behaviour of typical power plant branched pipe geometries. The effects of various geometric and material parameters on the creep stress and creep life behaviour of the connections are studied. In particular, the effect of the differing creep properties associated with the various material regions of the weld are investigated. The importance of incorporation of weld properties in creep life assessments is thus assessed. Finite element steady-state and continuum damage mechanics creep analyses have been used to identify the relative creep strength of typical connections compared to plain pipes. The work identifies typical creep rupture locations within branched pipe welds and the associated damage accumulation at and around these positions. Various creep life assessment methods/procedures are used in practise: these are mainly the British Standard codes, British Energy's R5 procedure, steady state creep approaches and continuum damage mechanics approaches. The relative accuracy and conservatism of these distinct approaches are addressed for the application to typical branched pipes. The general formulation of steady-state creep stress is applied to the parametric study of weld materials in a typical multi-material welded branched pipe. An approximate interpolation technique for power-law creep is implemented to reduce the number of analyses needed to span a wide range of material parameters. The method is used to estimate the creep stresses and lives at several critical regions within the various material zones of the weld. The advantages of the technique are related to the small number of analyses required and the simple and compact way of presenting the results for weld design and life assessment purposes.

APA, Harvard, Vancouver, ISO, and other styles

32

Ehnes, Charles W. "Damping in stiffener welded structures." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03Jun%5FEhnes.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

33

Lyons, John C. "Strength of welded shear studs." Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-06102009-063157/.

Full text

APA, Harvard, Vancouver, ISO, and other styles

34

Saunders, Frederick I. "Forming of tailor-welded blanks." Connect to resource, 1994. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1240337228.

Full text

APA, Harvard, Vancouver, ISO, and other styles

35

Saunders, Frederick Irvin. "Forming of tailor-welded blanks /." The Ohio State University, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487858106116087.

Full text

APA, Harvard, Vancouver, ISO, and other styles

36

Kasikci, Ilker. "Effect Of Gap Distance On The Mechanical Properties And Cross-sectional Characteristics Of The Mig-mag Butt Welds." Master's thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/1027283/index.pdf.

Full text

Abstract:

This study was undertaken with the objective of determining the effect of gap distance on the weld bead geometry and the mechanical properties of the weldments. Low-alloyed and low carbon steel plates were welded under different conditions where each weldment had different gap distance and weld bead grooves. The influences of welding parameters namely, welding speed, current and voltage on the weld bead were examined in terms of weld bead penetration and heat affected zone and weld metal zone hardness variations.

APA, Harvard, Vancouver, ISO, and other styles

37

Ohlsen, Niels [Verfasser], Ines [Akademischer Betreuer] Weller, Ines [Gutachter] Weller, and Uwe [Gutachter] Engel. "Klimawandelbewusstsein und Akzeptanz erneuerbarer Energien / Niels Ohlsen ; Gutachter: Ines Weller, Uwe Engel ; Betreuer: Ines Weller." Bremen : Staats- und Universitätsbibliothek Bremen, 2018. http://d-nb.info/118840640X/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

38

Tautenhahn, Lutz [Verfasser], Bernhard [Akademischer Betreuer] Weller, and Frank [Akademischer Betreuer] Wellershoff. "Entwicklung eines Befestigungssystems für Photovoltaikmodule / Lutz Tautenhahn. Gutachter: Bernhard Weller ; Frank Wellershoff. Betreuer: Bernhard Weller." Dresden : Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2015. http://d-nb.info/1072360136/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

39

Kothe, Michael [Verfasser], Bernhard [Akademischer Betreuer] Weller, and Andrij [Akademischer Betreuer] Pich. "Alterungsverhalten von polymeren Zwischenschichtmaterialien im Bauwesen / Michael Kothe. Gutachter: Bernhard Weller ; Andrij Pich. Betreuer: Bernhard Weller." Dresden : Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://d-nb.info/1068444932/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

40

Feng, Ran. "Design of cold-formed stainless steel tubular joints." Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/hkuto/record/B41290628.

Full text

APA, Harvard, Vancouver, ISO, and other styles

41

Weller, Sebastian [Verfasser]. "Die Aufbereitung gebrauchter Medizinprodukte / Sebastian Weller." Aachen : Shaker, 2011. http://d-nb.info/1070152358/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

42

Robertson, I. "Strength loss in welded aluminium structures." Thesis, University of Cambridge, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372908.

Full text

APA, Harvard, Vancouver, ISO, and other styles

43

Nguyen, N. T. "Advanced modelling of the fatigue of butt-welded structures : a thesis /." Title page, contents and abstract only, 1996. http://web4.library.adelaide.edu.au/theses/09PH/09phn576.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

44

Hemmerle, Claudia [Verfasser], Bernhard [Akademischer Betreuer] [Gutachter] Weller, and Volker [Gutachter] Quaschning. "Photovoltaik in der Gebäudehülle : Wertung bautechnischer Anforderungen / Claudia Hemmerle ; Gutachter: Bernhard Weller, Volker Quaschning ; Betreuer: Bernhard Weller." Dresden : Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://d-nb.info/1114067660/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

45

Simmer, Götz. "Gold und Sklaven : die Provinz Venezuela während der Welser-Verwaltung (1528 - 1556) /." Berlin : Wiss.-und-Technik-Verl, 2000. http://www.gbv.de/dms/sub-hamburg/317926160.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

46

Ferber, Magnus Ulrich. ""Scio multos te amicos habere" : Wissensvermittlung und Wissenssicherung im Späthumanismus am Beispiel des Epistolariums Marx Welsers d. J. (1558 - 1614)." Augsburg Wißner, 2008. http://deposit.d-nb.de/cgi-bin/dokserv?id=3117417&prov=M&dokv̲ar=1&doke̲xt=htm.

Full text

APA, Harvard, Vancouver, ISO, and other styles

47

Wu, Weidong Aerospace &amp Mechanical Engineering Australian Defence Force Academy UNSW. "Fatigue crack propagation behaviour of welded and weld repaired 5083 aluminium alloy joints." Awarded by:University of New South Wales - Australian Defence Force Academy. School of Aerospace and Mechanical Engineering, 2002. http://handle.unsw.edu.au/1959.4/38663.

Full text

Abstract:

Welding, as one of the most effective joining methods for metals, has been extensively applied in engineering usage for a long time. When cracks occur in the vicinity of weldments, weld repairs are frequently considered for crack repair to extend service life. In order to evaluate to what extent the weld repair has improved the fatigue life of a cracked welded structure, it is necessary to be able to determine the residual life of the cracked welded joint, as well as the life of the weld repaired joint. Both these assessments require that the fatigue crack growth data be available. The determination of crack propagation rates of welded and weld repaired structures is thus of paramount importance to implement a damage tolerant approach to structural life extension. However, since most studies on welded joints so far have concentrated on fatigue life evaluation, at the present time only limited information is available on crack propagation rates in welded joints, and virtually none on fatigue behaviour and crack propagation in weld repaired joints. This thesis has focused on examination of fatigue and crack propagation behaviour in as welded and weld repaired aluminium alloy 5083, a weldable marine grade alloy extensively used in construction of high speed ferries and aerospace structures. Crack growth rates were measured during constant amplitude fatigue testing on unwelded, as-welded and weld repaired specimens of 5083-H321 aluminium alloy. A 3-D finite element analysis was conducted to determine the stress intensity factors for different lengths of crack taking into account the three-dimensional nature of the weld profile. The effects of crack closure due to weld residual stresses were evaluated by taking measurements of the crack opening displacements and utilised to determine the effective stress intensity factors for each condition. Metallurgical examinations and fractography of the fracture surface were conducted using an optical microscope and SEM. It was found that crack growth rates in welded plates are of the same order of magnitude as those of parent material when effective stress intensity factors were applied. However weld repaired plates exhibit higher crack growth rates compared to those of unwelded and once-only welded plates.

APA, Harvard, Vancouver, ISO, and other styles

48

Fong, Siu Lung. "Corrosion study of laser welded stainless steels." Thesis, University of Macau, 2002. http://umaclib3.umac.mo/record=b1446156.

Full text

APA, Harvard, Vancouver, ISO, and other styles

49

Akbarnejad, Shahin. "Investigation on static strength of welded joints." Thesis, KTH, Materialvetenskap, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-104058.

Full text

Abstract:

Although high strength steels represent yield strength up to 1300 MPa, welded structures reveal lowerstrength values. The strongest commercially available electrode provides the yield strength of about900 MPa. Therefore, in welded steels with strength above this type of filler metal, achieving anacceptable global strength is a crucial issue. In this master thesis, affects of different welding procedures on static strength of welded jointsof Weldox 960 and Weldox 1100 steels, were studied. These steels are produced by SSAB inOxelösund. Meanwhile, finite element method analyses were applied in order to investigatethe static strength behavior of such weldments under uniaxial tension. The welding parameters which were selected as variables are: Heat input Weld joint geometry Filler metal When weld metal is undermatching in strength levels than the base material, by applyingtension the soft weld metal begins to deform before parent metal. At that point thedeformation of resulted soft zone, including the weld metal and the heat affected zone, ishindered by high strength parent metal. Thus, uniaxial stress caused by uniaxial load isconverted to multiaxial stress. This conversion in tension results in increase in the staticstrength of weldment. The increase in strength is emphasized by increase in the width of thewelded joint while the thickness of the plate is kept as constant. After experiments and performing FEM studies, it was revealed that the static strength ofWeldox 960 welded joints approaches towards the tensile strength of parent metal by increasein the width of the weldment. In Weldox 1100 joints; a slight increase in tensile properties ofthe weldments, when the width of the sample increases, was observed.

APA, Harvard, Vancouver, ISO, and other styles

50

Pasupuleti, Kirti Teja. "Slow strain rate testing of welded copper." Thesis, KTH, Materialvetenskap, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-116498.

Full text

Abstract:

In Sweden spent nuclear fuel is planned to be placed 500 m down in the bedrock. The spent nuclear fuel will be contained in copper canisters. The reason behind the selection of copper is its thermodynamic stability against corrosion in the depository. The copper will be exposed to mechanical loading and will be plastically deformed due to creep. The canisters will be sealed by friction stir welding. Since the canisters have to survive intact for many thousands of years, the properties of the welds are critical. Oxygen free P-doped copper (Cu-OFP) is selected for its excellent creep ductility properties and corrosion resistance. In this thesis work creep ductility behavior of friction stir welded copper chosen at different areas of the weld is evaluated by using the test slow strain rate tensile test. Samples are chosen at different weld areas namely weld, cross weld and HAZ. A sum of 21 specimens is tested. These tests are achieved at three various strain rates and each rate are carried out at three different temperatures. The strain rates used for tests are 1e-4, 3e-6 and 1e-7 [1/s]. The samples are strained until rupture, 20% and 5% of the gauge length. Yield strength and tensile strength are usually decreasing with increasing temperature and at higher temperature the material can be easily deformed. Few strange behaviors are also observed for the samples from HAZ areas at strain rate 1e-7[1/s]. The experimental results are justified by using the Knock-Mecking model. The parametersand ω were evaluated by curve fitting method.

APA, Harvard, Vancouver, ISO, and other styles

We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!