21 |
Návrh horizontální výměnné hlavy - VA1 –C / Design horizontal exchange of the head - VA1-CVyplašil, Jan January 2011 (has links)
Diploma thesis deals with the concept of interchangeable straight spindle head type VA1-C, used for automatic clamping in 80 kW spindle head from production of TOS Kuřim. Thesis contains survey of interchangeable heads, analysis of the spindle housing, strenght analysis of the spindle with the safety calculations in critical sec-tions and analysis of the clamping mechanism together with the calculation of the camping force, which holds the tools in the spindle. Analysis of the camping mechanisms contains calculation of the contact stress between balls and housings. All results are shown in the graphs. In the last part of the thesis are described the construction elements using the model of the interchangeable head. Enclosed is the assembly drawing of the spindle head, bill of material, detail drawing of the spindle and also 3D model of the interchangeable spindle head.
|
22 |
Okrajové podmínky ve válcovací mezeře při válcování za tepla a za studena / Boundary Conditions in the Roll Gap during Hot and Cold RollingLuks, Tomáš January 2016 (has links)
Boundary conditions in the roll gap play an important role in modelling of rolling processes. In the roll gap we can observe the following: changes of rolling pressure, changes of relative velocity, influences of oxides and lubrication, etc. When taking into account all conditions mentioned above the determination of the boundary conditions is not trivial and extensive measurements are necessary. Therefore, this thesis is dealing with design of temperature and force sensors specified for the determination of friction coefficient and heat transfer coefficient in contact. The temperature sensor with an installed thermocouple measures subsurface temperature for a given depth; and then the inverse heat conduction task is used to compute temperature and heat flux on the surface. Several temperature sensors were designed and used for measuring in pilot mill and industrial rolling mill as well. The thermal responses of different sensors were compared in the numerical simulations. The inverse calculations were tested for various rolling conditions. A durability of the sensors was also studied in industrial rolling conditions. The contact stresses in the roll gap were measured by a pin, which was in direct contact with the rolled material. The forces on the top of the pin were measured by a three-axes piezoelectric force transducer and recalculated to the contact stress and friction coefficient. The sensor was implemented in a work roll and tested when rolling aluminium and steel slab for different rolling conditions. The results were compared with the integrative force sensor ROLLSURF.
|
23 |
Study of Gear design Concept to Reduce Root Bending- & Contact Stresses for Automotive Transmission / Studie av kugghjulskoncept för att reducera rotböjs- & kontaktspänningar förväxel lådorLi, Felicia January 2019 (has links)
Advanced technologies for the automotive industry require improved designed precision in different areas. Research is needed in order to meet customer demand and satisfaction to increase durability, efficiency, and reliability. That is why continuous development in transmission system has been an exciting topic for many years. The gears in the transmission system demand high resistance against repeated loads acting on the teeth and the ability to engage without energy loss. The intention is to support that effort by investigating seven design cases of a parallel helical gear pair. This master thesis aims to study a gear design concept of adding a supporting ring to reduce the root bending- and contact stresses. To implement this study, seven different design cases were modelled to study the effect of changing the design. One or two support ring structures were added, or the thickness was increased of the gear considered exposed to high stresses. The purpose is to gain a comparative advantage in the automotive industry. M1 is a reference standard design, while the other models (M2-M5/P1-P3) are modified designs with additional rings or changed in thickness. Simulation is an effective and an useful tool to understand and visualize how the complex interaction of the transmission component appears to be. A finite element method (FEM) program was used to investigate these models. The gear pairs were imported into the pre-processor ANSA, the FEM program Abaqus 2017 was used as a solver, and the results were extracted from the post-processor META. To support the aim of this thesis, two of the seven FEM models were validated against a specialized gear calculated program, WindowsLDP, in order to determine the robustness of the simulation models. The transmission error (TE) measurements, root bending- and contact stresses were observed for the validation. Introducing the different models M3-M5 and P1-P3, the root and contact stresses were reduced by 1.2-4.4 and 0.07-4.3 %, respectively, compared to M1. The transmission error TE could differ as much as 85% in M2-M3 as compared to M1. Systematic errors were generated in model M2, therefore the low root stresses obtained in M2 should be considered carefully. Implementing the so-called misalignment measurement, tilting parameter, microgeometry, and profile modification related to crowning and tip relief is discussed and believed to reduce TE measurements, root- and contact stresses. These modifications have not been studied in this thesis. The LDP results showed a trend of higher values compared to the FEM results, which was suggested to be further investigated in the future. / Dagens avancerade teknik inom fordonsindustrin kräver förbättrad precision hos konstruktioner inom olika områden. Forskning behövs för att möta kundernas efterfrågan och för att öka hållbarhet, effektivitet och tillförlitlighet. Detta är varför kontinuerlig utvecklingen av växellådssystem har varit ett hett ämne i många år. Kugghjulstransmission skall ha högt motstånd mot upprepande belastning som förekommer på tänderna och skall även ha en minimal energiförlust. Detta examensarbete siktar mot att stödja den fortsatta utvecklingen inom området genom en fallstudie, mer specifikt för att studera sju olika kugghjulsmodeller som behandlar ett parallellt spiralformade kugghjul. Målet med detta examensarbete är att studera ett kugghjulskoncept där en ring appliceras för att reducera rot- och kontaktspänningar. Utförandet sker genom att studera sju olika modeller, för att veta hur stor påverkan designen utgör. En eller två stödringstrukturer appliceras, eller att öka kuggbredden på det kugghjul som anses vara det mest kritiska för höga spänningar. Denna studie görs för att kugghjulstillverkaren ska vara i utvecklingens framkant och kunna konkurrera inom fordonsindustrin. M1 ären referens och standard designmodell, medan de andra modellerna (M2-M5/ P1-P3) är modifierade design där med ytterligare ringar eller ändrad kuggbredd. Simulering är en effektiv metod för att förstå och visualisera komplexiteten av komponenter inom växellådan. Ett finita elementmetodens program användes för att undersöka dessa modeller, genom att importera geometrierna till pre-processorn ANSA, där Abaqus 2017 användes som en lösare, där sedan resultaten extraheras från post-processorn META. För att stödja denna studien användes två av de sju FEM-modellerna till att valideras mot ett annat specialiserat kugghjulsprogram inom kuggberäkning som heter WindowsLDP. Detta med avsikt att fastställa simuleringsmodellernas robusthet. Det så kallade överföringsfelet, rotböjnings- och kontaktspänningarna var ingående parametrar som behandlades under valideringen. Modellerna M3-M5/P1-P3 introducerades, där rotböjsspänningen och kontaktspänningen reducerades med 1.2-4.4 och 0.07-4.3% när de jämfördes med M1. Överföringsfelet (TE) kunde skilja upp mot 85% mellan M2-M3 jämfört med M1. Ett systematiskt fel uppstod i modell M2, modellens robusthet kunde därmed ej fastställas, då modellens resultat bör övervägas noggrant. Införande av så kallade växelförskjutning, lutning/vippning parametrar, mikrogeometrier och profilmodifieringen relaterat till kronning och tipavlastning, kommer att genera minskade TE-mätningar samt rot- och kontaktspänningar för de spiralformade kugghjulen. Dessa ämne har ej studerats under detta examensarbete. LDP-resultaten visade högre värden relativt jämfört med de FEM resultat, där en trend kunde observeras. Slutsatsen föreslog att detta bör undersökas ytterligare i framtiden.
|
24 |
Contribution à la détermination de surfaces conjuguées pour la transmission de puissance.Guyonneau, David 16 July 2013 (has links)
Les travaux présentés à travers ce manuscrit s'inscrivent dans un contexte de recherches exploratoires sur l'optimisation des surfaces engrenantes. Après une étude approfondie de l'emploi des engrenages dans un environnement aéronautique, l'élaboration d'une nouvelle méthodologie de génération de profils de denture est proposée. Les travaux s'attachent à caractériser le comportement mécanique spécifique d'un montage d'engrenages dans les Boites de Transmission de Puissances (BTP) d'hélicoptère.Un outil informatique a été créé dans le module VBA (Visual Basic Application) d'Excel. Il permet de créer automatiquement des profils de denture conjugués et optimisés. Il a l'avantage de définir analytiquement plusieurs grandeurs physiques. L'outil a ainsi pour objectif de proposer des profils de denture optimisés selon plusieurs critères. Les « objectifs » retenus sont le rendement et la contrainte équivalente de Hertz au contact suivant le critère de Von Mises.Les travaux s'articulent autour de trois axes : - la reconstruction de profils conjugués de denture par une approche novatrice basée sur le « contact », - la construction de critères physiques (glissement, pression, contrainte, …), - la recherche de profils de denture optimaux en utilisant la simulation de Monte Carlo.Enfin, la perspective de rendre générique cette méthode afin qu'elle puisse générer n'importe quels types d'engrenage est envisagée en fin de manuscrit. / The work described in the present manuscript is part of exploratory researches dealing with gears meshing surfaces optimization. After a short study of gears used in an aeronautical environment, the development of an innovative tool for tooth profile design is defined. Then, the specific behavior of a gear mesh within a helicopter main gearbox (MGB) is evaluated.A VBA software has been coded under MS Excel to generate conjugated and optimized gear tooth profiles. It advantageously defines and uses several physical parameters with their analytical formulation. The software provides at the user optimized tooth profiles according to a couple of criteria. The two “objective” functions evaluated are the efficiency and the Hertz equivalent stress within the contact using the Von Mises criterion.The work has been focused on three aspects:- The design of conjugated tooth profiles by contact sharing,- The definition of the relevant physical parameters,- The optimization of tooth profiles using Monte Carlo SimulationEventually, a generic method to design gear profiles, taking into account any physical parameters related to a gear mesh, could be expected as a future of this thesis work.
|
25 |
Návrh testovacího stavu pro stanovení opotřebení u kontaktu železničního kola a kolejnice / Design of a test condition for determining the wear at the contact of a railway wheel and railRec, Matouš January 2021 (has links)
This diploma thesis focuses on the issue of a wear of a railway wheel and a rail. The wear of the components depends on a number of parameters including the contact stress, the contact pressure and the contact surface dimensions. Among the factors determining these parameters belongs primarily the wheel driving gauge, the rail profile and the load of the contact area. Furthermore, the material from which the wheels and rail are made, the roughness and hardness of the functional surfaces and the residual stress in the material have a significant impact on the wear. All the parameters mentioned above are designed for the production of the railway wheels and rails and therefore they meet the standards for the production of these components. However, the existence of the changeable parameters has also a significant impact on the wear. These parameters include the presence of contaminants, or lubricants in contact, the changing driving gauge due to the wear, the slip ratio or the friction coefficient. With the wear being an inevitable process during the application it cannot be eliminated but only controlled. Applying the lubricant into the contact when passing through the arc in order to achieve an ideal coefficient or the maintenance grinding for restoring the driving gauge can serve the purpose. If properly optimized, the importance of the wear research lies in the financial savings. Being the crucial factor for optimization of the intervals between the maintenance grinding, the research is also beneficial. A high-quality wear prediction can be seen as the key field in order to increase the safety of the railway vehicles operation as well. Therefore, the wear research is made using several methods, such as the computational models, the multi-body dynamics software and the technical experiments. This thesis introduces a conceptual design of the test, enabling the wear research via experimental approach. The final device is capable of a simulation of both volume and fatigue wear during the states the railway wheel and railway undergo including riding on the straight track, passing through an arc or a wheel slip during braking.
|
26 |
Two and Three-Dimensional Finite Element Analysis of Plasticity-Induced Fatigue Crack Closure: A Comprehensive Parametric StudySolanki, Kiran N 13 December 2002 (has links)
Finite element analyses are frequently used to model growing fatigue cracks and the associated plasticity-induced crack closure. Two-dimensional, elastic-perfectly plastic finite element analyses of middle-crack tension (M(T)), bend (SEB), and compact tension (C(T)) geometries were conducted to study fatigue crack closure and to calculate the crack opening values under plane-strain and plane-stress conditions. The loading was selected to give the same maximum stress intensity factor in both geometries, and thus similar initial forward plastic zone sizes. Mesh refinement studies were performed on all geometries with various element types. For the C(T) geometry, negligible crack opening loads under plane-strain conditions were observed. In contrast, for the M(T) specimen, the plane-strain crack opening stresses were found to be significantly larger. This difference was shown to be a consequence of in-plane constraint. Under plane-stress conditions, it was found that the in-plane constraint has negligible effect, such that the opening values are approximately the same for the C(T), SEB, and M(T) specimens. Next, the crack opening values of the C(T), SEB and M(T) specimens were compared under various stress levels and load ratios. The effect of a highly refined mesh on crack opening values was noted and significantly lower crack opening values than those reported in literature were found. A new methodology is presented to calculate crack opening values in planar geometries using the crack surface nodal force distribution under minimum loading as determined from finite element analyses. The calculated crack opening values are compared with values obtained using finite element analysis and more conventional crack opening assessment methodologies. It is shown that the new method is independent of loading increment, integration method (normal and reduced integration), and crack opening assessment location. The compared opening values were in good agreement with strip-yield models.
|
27 |
Porovnání návrhů monolitické konstrukce bez a se zohledněním postupu výstavby. / Comparision of design of cast-in-place structure with / without consideration of process constructionVlach, Jakub January 2015 (has links)
The aim of this thesis is to propose and evaluate static three-storey reinforced concrete structure. For static analysis supporting structure was used computer program based on FEM SCIA - Engineer 2013 - student version. In computing program have been two independent computational models and in 2D and 3D space. The results were compared and evaluated with each other. On the basis of the report is drafted drawings consisting of reinforcement drawing and drawing shape.
|
28 |
Verformungen und Spannungen von Kegelradverzahnungen effizient berechnetSchaefer, Steffen 06 September 2018 (has links)
Diese Arbeit beschäftigt sich mit speziellen Methoden zur näherungsweisen Berechnung der Zahnverformungen sowie -spannungen im Kontext der Zahnkontaktsimulation von Kegelrad- und Hypoidverzahnungen. Die näherungsweise Berechnung ermöglicht kurze Simulationszeiten und ist damit die Voraussetzung für eine effiziente Verzahnungsoptimierung. Die Anwendung neuer Fertigungsverfahren ermöglicht es, dabei geometrische Ausprägungen des Zahnprofils, Zahnfußes und der Flankentopologie zu realisieren, die mit den speziellen Methoden der näherungsweisen Berechnung bisher nicht oder nur unzureichend genau abgebildet werden können. In der vorliegenden Arbeit werden deshalb Näherungsmethoden entwickelt, mit denen z.B. auch Zahnprofile mit großer Asymmetrie, elliptischen Zahnfußkurven und logarithmischen Flankentopologiemodifikationen zuverlässig berechnet werden können.:1 Einleitung
2 Stand der Technik
2.1 Zahnkontaktsimulation
2.2 Die Verzahnungsgeometrie als Basis der Zahnkontaktsimulation
2.3 Methoden für die Zahnkontaktsimulation
2.3.1 Komplexe Methoden für die Verformungs- und Spannungsberechnung
2.3.2 Näherungsmethoden für die Verformungs- und Spannungsberechnung
2.4 Verzahnungen mit Sondermerkmalen
3 Zahnkontaktsimulation auf Basis der Einflusszahlenmethode
3.1 Herangehensweise bei der Betrachtung
3.2 Zerlegung der Verformungen und Spannungen in lineare und nicht lineare Anteile
3.3 Annahmen für die Formulierung des Zahnkontaktproblems
3.4 Bestimmung der potenziellen Zahnkontakte
3.5 Einflusszahlenmethode
3.6 Lösung des reibungsfreien Zahnkontaktproblems
3.7 Radkörpereinfluss
3.8 Wechselwirkung zwischen den Zähnen
4 Näherungsweise Biegeverformungsberechnung
4.1 Vereinfachung der Verzahnungsgeometrie
4.2 Berechnungsmethode
4.3 Allgemeine Verformungsabklingfunktion
4.3.1 Allgemeine Verformungsabklingfunktion für den unendlich langen Zahn
4.3.2 Allgemeine Abklingfunktion für den endlich langen Zahn
4.3.3 Berechnung der Zahnverformung unter Einzelast mittels FEM
4.3.4 Einfluss der Kraftangriffshöhe und der Profilform
4.3.5 Fehlerverhalten der allgemeinen Verformungsabklingfunktion
4.3.6 Einfluss der veränderlichen Normalschnittgeometrie
4.4 Bezugswert der Biegeverformung
4.4.1 Näherungslösung
4.4.2 Wahl einer Methode zur Verbesserung der Bezugswertberechnung
4.4.3 Auswahl des BEM-Verfahrens
4.4.4 Verfahrensbeschreibung für das BEM-Programm-Modul
4.4.5 Auswertung der BEM-Verformungen an der Stelle einer Streckenlast
4.4.6 Überprüfung des BEM-Programm-Moduls und Genauigkeitsbewertung
4.4.7 Effiziente Berechnung des BEM-Bezugswerts
4.5 Korrekturen für den Ersatzzahn
4.5.1 Stirnseitenunstetigkeit
4.5.2 Krümmungseigenschaften des Zahnes
4.6 Zahnberandungseinfluss
4.7 Berechnung der verbesserten Biegeverformungseinflusszahlen
5 Näherungsweise Berechnung der Kontaktverformung und -spannung
5.1 Vereinfachung der Kontaktgeometrie
5.2 Berechnung der Kontaktverformungseinflusszahl und der Kontaktspannung mit der ZZM
5.3 Komplexe Einflüsse auf die Kontaktverformung und -spannung
5.3.1 Wechselwirkungseinfluss
5.3.2 Zahnberandungseinflüsse
5.4 Erweiterung der ZZM zur Berücksichtigung von Kopfkanten
5.5 Verbesserte Berechnung der Kontaktverformungseinflusszahl und der Pressung
6 Näherungsweise Berechnung der Zahnfußspannung
6.1 Berechnungsmethode
6.2 Allgemeine Spannungsabklingfunktion
6.2.1 Allgemeine Spannungsabklingfunktion für den unendlich und endlich langen Zahn
6.2.2 Einfluss der Kraftangriffshöhe und der Profilform
6.2.3 Fehlerverhalten der allgemeinen Spannungsabklingfunktion
6.3 Bezugswert der Zahnfußspannung
6.4 Korrektur für den Ersatzzahn
6.4.1 Einfluss des Schrägungswinkels auf die Zahnbreitenlage des Zahnfußspannungsmaximums
6.4.2 Stirnseitenunstetigkeit
6.4.3 Einfluss der Zahnwindung auf die Zahnfußspannung
6.4.4 Einfluss der Flankenlinienkrümmung auf die Zahnfußspannung
6.5 Berechnung der Zahnfußspannung nach der verbesserten Methode
7 Verifikation und Validierung der verbesserten Berechnungsmethoden
7.1 Herangehensweise bei der Verifikation und Validierung
7.2 Verifikation
7.2.1 Allgemeine Vorbetrachtungen zur Genauigkeit
7.2.2 Sensibilitätsstudie
7.3 Validierung
7.3.1 Vorgehensweise bei der Validierung
7.3.2 Ausgewählte Messungen von Paul
7.3.3 Tragbildvergleich an Praxisverzahnungen
7.4 Konvergenzverhalten bei der Zahnkontaktsimulation mit BECAL-BEM
8 Zusammenfassung und Ausblick
|
Page generated in 0.0528 seconds