|
|
Influence of shape of the electrode to weld pool
Hrádek, Jan ; Vaněk, Mojmír (referee) ; Kubíček, Jaroslav (advisor)
The project is focused on welding of TIG method. In this method is used non-melting tungsten electrode, which can have different top angles. In different literature there are different opinions about how angle influence weld pool. It was sharpen six different angles of electrode with whom was done welds on carbon steel S235JR and on austenitic corrosion resistant steel x5CrNi1810. The evaluation was done with help of chart where on the axis x is angle of electrode and on axis y are depth and width weld in millimiters. The result of this project was the prove of opinion that with more sharper angle of electrode is depth of weld smaller and width bigger.
|
|
|
Stick welding carbon and high-alloy steels
Hendrych, Marek ; Vaněk, Mojmír (referee) ; Kubíček, Jaroslav (advisor)
This thesis deals with analysis of manual metal arc welding method or method 111. In the research part of this thesis are discused principles of this method, welding power sources and additional welding material-coated elecrodes. Further the thesis is focused on the weldability of steels, especially carbon steels and austenitic stainless steels. In the experimental part was accomplished measurement of operational characteristics of coated electrods. Measurement was carried out on sample of cabon steel S235JR according to ČSN EN and austenitic stainless steel X5CrNi18-10 accordig to ČSN EN. The evaluation envolves a comparison of the results and their justifications.
|
|
|
Loss of strength during welding aluminous alloys AW 6060
Sklenář, Martin ; Vaněk, Mojmír (referee) ; Sigmund, Marian (advisor)
The aim of the bachelor thesis is to qualify the welding procedure according to the standard ČSN EN ISO 15614-2. At the beginning of the work is introduced a company with which was this thesis made. This is followed by an assessment of the issue of aluminum. Furthermore, the mechanical properties of aluminum are discussed. Follows by part about welding specially about aluminium welding. In the practical part the samples were welded and subsequently evaluated, then the design and qualification of the welding process was made. In conclusion, the possibilities and results that have been achieved are summarized.
|
|
|
Development of Models of Al Alloys Behaviour for Applications in Numerical Simulations of Welding and Heat Treatment
Vaněk, Mojmír ; Věchet, Stanislav (referee) ; Neumann, Heinz (referee) ; Daněk, Ladislav (advisor)
The thesis deals with methodology for computational approaches for numerical simulations of welding and heat treatment of aluminium alloys. The thesis describes improvement of the current methodology for metallurgical part of the numerical analysis of welding, which is important mainly for prediction of dimensions of the heat affected zone (and deformations). The improvement was carried out based on CHD diagram that describes precipitation and dissolution of phases during continuous heating. The thesis also describes carried material measurements (measurement of chemical composition, dilatometric tests, tensile tests of several conditions of materials at temperatures up to 500 °C and measurement of aging curves), which allowed to significantly refine analysis results for the alloys EN AW-5083 and EN AW-6082. Based on an evaluation of the measurements, several conclusions were made. They can be useful for creation of material databases of other aluminium alloys. The thesis also describes quantification of dependence between tensile strength and yield strength on the Vickers hardness for different conditions of EN AW-6082. There is also methodology for numerical simulation of the heat treatment process of heat treatable Al alloys in the dissertation. The methodology is completely new approach which has never been published so far. Application of this method is based on user changes of the material database in software Sysweld after relatively easy measurement of aging curves. Therefore, the methodology can be considered as promising for application in industrial practice.
|
|
|
Influence of Chemical Composition on Weldability of Structural Steels
Kachlíř, Jaromír ; Daněk, Ladislav (referee) ; Vaněk, Mojmír (advisor)
This work deals with the influence of chemical composition to weldability of construction steel S355, S275 and S235. The introduction is about marking steel according to norms EN 10027 and CSN 42 0002. It also marginally deals with the problematic of carbon equivalents, temperature of preheat and generation of martenzit during welding. The second half contains the evaluation of the examined steel samples. I focus mostly on mechanical properties, chemical composition and other steel charasteristics. All the samples are compared both to the other steels in its group and amongst each other.
|
|
|
Prediction of welding joint distortion by computer simulation.
Vaněk, Mojmír ; Slováček, Marek (referee) ; Daněk, Ladislav (advisor)
In this master’s thesis there are set down dependencies of distortion of T-joints on the size of heat input and welding speed. Dependencies were found for single- and double-fillet welds, for single- and multiple-pass welding. The computer simulations were carried out in programs Visual-Weld and SYSWELD. The size of the melted zones, stress fields, material structure and hardness of the weld specimens were specified. Simulation results were compared with experimentally detected values.
|
|
|
Proposal of welds number reduction on aluminium aloys frame doors for rail vehicles
Šplíchal, Jan ; Vaněk, Mojmír (referee) ; Sigmund, Marian (advisor)
This Diploma thesis presents possible proposals of welds number reduction frame doors for rail vehicles welded from profiles from aluminium alloy EN AW 6060, which is heat treated by temper T66. Profiles are welded by TIG process with additional material S Al 5087 (AlMg4,5MnZr). The heat treatment by the welding cycle causes a change in structure of basic material and decrease of mechanical properties due to dissolution of precipitates. To measure the necessary mechanical properties of the material after welding a tensile test was performed on the delivered samples. The resulting values from tensile test were subsequently used as cut – off values in the new door frame design by FEM simulation in Virtual Performance Solution software with PAM – Crash extension. The newly designed frame was welded according to the necessary welding procedure specifications, which are also part of the thesis. The conclusion is devoted to the economic evaluation of the current and new design of the door frame.
|
|
|
Analysis of the Production Processes Influence on Rail Deformations
Skalník, Vít ; Podaný, Kamil (referee) ; Vaněk, Mojmír (advisor)
The aim of this work is to assess the possibilities of using numerical simulation tools in the process of laser welding of the guide rail of a car seat. In the diploma thesis, a description of the components and the problem, which consists in the deformation of the groove of the guide rail, was made. A description was made of the manufacturing operations that the components go through. The positives of selected welding methods were evaluated and the choice of those used in production was justified. A description of the issues of laser welding, deformation and the use of simulation tools was made. The influence of individual production operations was evaluated in terms of the size and nature of deformations. Using the Visual – Mesh, Visual – Weld and Visual – Assembly simulation tools, which are products of the French company ESI Group, the same state of the simulated and real process was achieved. Subsequently, a proposal for the elimination of deformations and its verification using a simulation tool could be approached. The use of a spacer wedge, which acts on the most deformed places of the groove, was proposed. By its application, the resulting deformations were eliminated or significantly reduced. In the last part of the work, a technical and economic evaluation was made, taking into account the current global crisis and the important role of the automotive industry.
|
|
|
Synthesis and biological evaluation of novel uncharged cholinesterase reactivator against nerve agent intoxication
Vaněk, Mojmír ; Roh, Jaroslav (advisor) ; Krátký, Martin (referee)
Charles University Faculty of Pharmacy in Hradec Králové Department of Organic and Bioorganic Chemistry Student: Mojmír Vaněk Supervisor: doc. PharmDr. Jaroslav Roh Ph.D. Advisors: PharmDr. Jan Korábečný Ph.D.; PharmDr. Vendula Hepnarová Ph.D. Title of diploma thesis: Synthesis and biological evaluation of novel uncharged cholinesterase reactivator against nerve agent intoxication Nerve agents (NPL) and pesticids are strongly toxic organophosphorus compounds with high affinity to acetylcholinesterase (AChE) enzyme. This enzyme is present in CNS and neuromuscular synapses. The intoxication leads into an acute cholinergic crisis, which can ultimately results into death. The therapy must be quick and includes application of atropine, reactivators of AChE and diazepam. Among the commonly used AChE reactivators, mono- or bis- quarternary aldoximes cen be found. These compounds are permanently charged, so their penetration through the blood-brain barrier (HEB) is very limited (up to 10 %, often only 1-3 %). Within the diploma thesis, a non quarternary AChE reactivator has been developed by multiple-steps synthesis approach. This compound, denoted as K1396, would exert high ability to penetrate through HEB. In vitro assessments of his capability to reactivate AChE has been carried out by method of Ellman....
|
|
|
Loss of strength during welding aluminous alloys AW 6060
Sklenář, Martin ; Vaněk, Mojmír (referee) ; Sigmund, Marian (advisor)
The aim of the bachelor thesis is to qualify the welding procedure according to the standard ČSN EN ISO 15614-2. At the beginning of the work is introduced a company with which was this thesis made. This is followed by an assessment of the issue of aluminum. Furthermore, the mechanical properties of aluminum are discussed. Follows by part about welding specially about aluminium welding. In the practical part the samples were welded and subsequently evaluated, then the design and qualification of the welding process was made. In conclusion, the possibilities and results that have been achieved are summarized.
|
guest ::
