1,721,110 research outputs found
Analytical derivation of Hertzian contact theory and analysis of parameters
Full text linkZaključna naloga obsega analitično izpeljavo kontakta dveh teles in porazdelitve tlaka v kontaktu, kot posledico normalne pritisne sile. Obravnavan je tudi vpliv materialnih in geometrijskih parametrov na izračun največjega tlaka in velikosti kontakta. V zaključku naloge je opravljena primerjava Hertzove izpeljave in poenostavljene izpeljave porazdelitve tlaka, ki je bila obravnavana v tretjem letniku razvojno raziskovanega programa na Fakulteti za strojništvo.Final work includes analytical derivation of a contact between two bodies and the pressure distribution in the contact, as a result of the normal force. The influence of material and geometric parameters on the calculation of the maximum pressure and the size of the contact is also considered. Comparison between Hertzian derivation and the simplified derivation of pressure distribution is represented in the conclusion. The simplified derivation was lectured in the third year of a research program at the Faculty of Mechanical Engineering
Analysis of bearing loads in automotive electric actuator
Full text linkPri izdelavi zaključne naloge smo se lotili problema obremenitve drsnih ležajev na osi solenoidnega aktuatorja. S pomočjo znanih gabaritov ter obratovalnih sil smo z uporabo programske opreme izvedli analizo obremenitev ležajev po metodi končnih elementov. V nadaljevanju smo na kontaktih med osjo ter ležaji določili še vrednosti Hertzovega tlaka.The main topic of my thesis was the problem of slide bearing loads in solenoid actuator. Values of gauges and outer forces were preliminary known which enabled us to make a finite element analysis of bearing loads using software. In addition we analysed the contacts between axis and bearings which led to the results of Hertzian contact pressure
Description of creep master curves with a time-temperature parameter
Full text linkMagistrsko delo predstavlja izpeljavo in oblikovanje splošnega matematičnega modela za popis deformacijskega mehanizma lezenja ter njegovo naknadno pretvorbo v uporabno numerično obliko. V praksi se zaradi enostavnosti in hitrosti računalniškega procesiranja, za popis lezenja, uporablja aproksimacijski polinom 2. stopnje. Z njim z zadovoljivo kakovostjo popišemo set eksperimentalnih točk v področju visokih in srednjih temperaturnih in napetostnih nivojev, v področju nizkih temperatur in napetosti pa z njim ne moremo celovito zajeti fizikalnega dogajanja. V ta namen smo, z uporabo metode najmanjših kvadratov, zapisali splošni numerični model ter na primeru eksperimentalnih točk dveh vrst jekel (1.25Cr0.5Mo in 5Cr0.5Mo) izoblikovali zdržljivostne krivulje z uporabo aproksimacijskih polinomov 2., 3., 4. in 5. reda ter jih medsebojno primerjali. Ugotovili smo, da s polinomi višjih redov bolj natančno popišemo ekstrapolirano območje nizkih napetosti in temperatur, vendar njihova korektna fizikalna vpeljava zajema tudi veliko izzivov. V splošnem se izkaže, da je metoda zelo občutljiva na raztros podatkov, poleg tega pa se, še posebej v primeru polinomov višjih redov (>2.), zaradi večje prostosti lahko pojavi fizikalno neutemeljena usmeritev zdržljivostnih krivulj. To nam daje vedeti, da je za večjo stabilnost numeričnega modela potrebno definirati dodatne pogoje, s katerimi bi njihovo gibanje omejili.The master thesis presents the evolution of a mathematical and later on, numerical model that defines the creep deformation mechanism. Due to limitations of computational speed, in reality, a 2nd-degree approximation polynomial is used, which enables a quality presentation of the high and middle temperature and stress zoneshowever, in the low temperature and stress zone, it does not consider the physical phenomena that are related to creep. For that reason, the emph{Least Square Method} was used to define a general numerical model that was later on tested on two materials (1.25Cr0.5Mo and 5Cr0.5Mo). By using it, we formed 2nd, 3rd, 4th and 5th-grade master curves and compared them to each other. We determined that higher grade polynomials enable physically better definition of the extrapolated low temperature and stress zonehowever, their usage also creates several problems related to data scatter. This is especially proven with higher grade polynomials (> 2nd) due to more degrees of freedom, which can result in a physically incorrect behavior of the master curves. This clearly indicates that in order to establish a stable and robust numerical model, additional conditions need to be applied
Comparison of the calculation of damage due to fatigue with energy models
Full text linkPri uporabi različnih metod določanja dobe trajanja, oziroma metod za izračun poškodb materiala v določenem obremenitvenem ciklu, je potrebno izhajati iz eksperimentalno pridobljenih podatkov za določeni material.
Z namenom proučitve različnih metod in njihove primerjave z uveljavljenimi napetostnimi in deformacijskimi metodami, smo v okviru magistrskega dela obravnavali energijske modele izračuna poškodbe in jih primerjali z napetostnimi in deformacijskimi modeli. Dodatno smo medsebojno primerjali več korekcij srednjega nivoja napetosti, katere so formulirane na nivoju histerezne energije. Sledila je simulacija napetostno-deformacijskega stanja za izbrane obremenitvene cikle in izračun poškodbe. Za oceno učinkovitosti energijskih modelov smo dodatno obravnavali viskoplastične modele, ki so namenjeni korekciji vpliva časovne komponente na utrujanje gradiva. S postopkom vrednotenja energijskega poškodbenega parametra smo pričeli na podlagi pridobljenih eksperimentalnih podatkov meritev dob trajanja, ki so dostopni v objavljeni strokovni literaturi. Sledila sta določevanje parametrov modelov in izračun dob trajanja za posamezni model oziroma korekcijo.
Ugotovili smo, da je pri uporabi energijskih modelov prisoten potencial, ker smo dobili primerljive rezultate z deformacijskimi modeli, v določenih primerih pa so rezultati bili celo bolj točni in z manj raztrosa.When using different fatigue life estimation methods or fatigue damage estimation methods for a given load cycle, the experimental data for a given material must be acquired first.
In this master\u27s thesis we discussed energy models for fatigue damage calculation and compared them with stress and strain models, with the purpose of studying different methods and their comparisons with well-established stress and strain methods. In addition, we compared several mean stress corrections methods whose formulation is based on energy of closed hysteresis loop. Next we simulated stress strain states for the selected load cycles and calculated the corresponding fatigue damage. Additionally we discussed viscoplastic models that include the effects of time component on the fatigue life to further evaluate the efficiency of energy models. We started the process of evaluating energy models on the basis of obtained experimental data of fatigue life measurements, which is available in the published literature. Next we calculated all model parameters and estimations of fatigue life for each discussed model and correction.
We have found potential in usage of energy models, due to comparable results with strain models, and in certain cases the results were even more accurate and with less scatter
Development of a device for cutting fruits and vegetables
Full text linkPrezentacija hrane je bistvenega pomena za dojemanje njenega okusa. Posebej pomembna je pri manj privlačnih živilih, kot sta sadje in zelenjava, saj lahko spodbudi k večjemu uživanju le-teh. Poleg same postavitve na krožniku je pri sadju in zelenjavi pomembno tudi, kako ju narežemo.
V tem delu se ukvarjamo z razvojem konceptualne rešitve naprave za rezanje sadja in zelenjave, ki omogoča tudi lupljenje. Poslužimo se ustaljenih postopkov razvoja novega izdelka, kjer najprej določimo specifikacije izdelka, naredimo analizo trga ter določimo idealne in mejne vrednosti specifikacij. Nato definiramo tehnični proces, funkcijsko strukturo in nazadnje morfološko matriko, ki nam služi pri pripravi različnih konceptualnih rešitev.
Pripravili smo dve različni konceptualni rešitvi, ki smo ju ocenili po tehnoloških in ekonomskih kriterijih. Boljšo rešitev smo nato še izpopolnili in pripravili za potencialni nadaljnji razvoj do končnega izdelka.The presentation of food is crucial for our perception of its taste. It is especially important with foods that look less appealing, such as fruits and vegetables, because it can encourage us to eat more of those. Additional to the arrangement on the plate, with fruits and vegetables it is also very important how they are cut.
In this thesis we are developing a concept of a device for cutting fruits and vegetables, which also enables peeling. We work according to the established development process, where we first determine specifications of the product, analyse the market, and determine ideal and borderline values of specifications. After that we define the technical process, functions structure and morphological matrix, which aides us in the development of different concepts.
We have developed two different concepts, which we then evaluated based on technical and economical criterion. We further developed the better solution and prepared it for a potential development to the final product
Development of latex threshing machine
No full textV okviru turističnih dogodkov obujanja tradicije pridelovanja in obdelovanja lanu smo na domači kmetiji zaradi večjega povpraševanja po ekološko pridelanem lanenem semenu opazili potrebo po strojnem mlatenju. Zato se zaključna naloga osredotoča na razvoj priročne mlatilne naprave, ki bi zadostila potrebam za domačo pridelavo lanu kot tudi za demonstracijo omenjenega postopka. Ker je tovrstna rastlina in njena strojna obdelava ljudem manj poznana, smo v začetku naloge opisali lastnosti lanu in tudi razložili delovanje mlatilnih naprav. Temu je sledila analiza trga, kjer smo ugotovili, da slovensko tržišče ne ponuja mlatilne naprave, ki bi zadostila našim potrebam. Zato smo se lotili razvoja nove naprave na osnovi naših zahtev in želja. Iz konstrukcijskega zahtevka smo izpeljali, katere funkcije mora naprava izpolniti. Na ta način smo razdelali funkcijsko strukturo, ki je služila kot izhodišče za iskanje delovnih principov. Na podlagi morfološke matrike smo naredili nabor treh konceptov ter jih v nadaljevanju ocenili tako s tehničnega, kot ekonomskega vidika. Na koncu smo konceptu z najvišjo skupno oceno za njegovo delovanje izbrali ter dimenzionirali glavne strojne elemente.In light of turistic heritage to revive the tradition of flax production we have noticed the need for flax machine threshing on our family farm due to the increased demand for organically produced flax seed. Therefore, the thesis focuses on the development of a convenient threshing machine to meet the needs for home flax production as well as to demonstrate the process. Since this type of plant and its machining are less known to people, the thesis opens with a description of flax and its properties and introduces the operation of the threshing machine. This is followed by an analysis of the market, where I have discovered that the Slovenian market does not offer a threshing machine that meets our needs. We have therefore set out to develop a new device based on our requirements and wishes. From the design requirement, we have derived which functions the device must meet, and in this way we have created a functional structure that serves as a starting point of principles of operation. On the basis of the morphological matrix, a set of three concepts have been created and further evaluated from both a technical and an economic point of view. Finally, the concept with the highest overall score for its performance has been selected and the main hardware elements have been dimensioned
Optimization of material consumption for the production of support elements of the vessel
No full textV današnjih časih morajo podjetja nenehno skrbeti za svoj obstoj na tržišču. To poskušajo doseči na različne načine. Eden izmed teh je uporaba naprednih računalniških orodij. Ta jim omogočajo izdelavo virtualnih 3D modelov svojih proizvodov, s katerimi se lahko hitreje in ekonomsko učinkoviteje odzivajo na zahteve trga. Pri končni odločitvi o dejanski izvedbi morajo poleg rezultatov, pridobljenih z računalniškimi orodji, upoštevati tudi ostale proizvodne stroške.In today\u27s competitive market environment, companies must continuously strengthen their market position. One effective strategy involves the use of advanced computer technologies. These tools enable the creation of virtual 3D models of their products, allowing businesses to respond more rapidly and cost-effectively to market demands. However, when it comes to making final decisions regarding actual production, companies must also consider additional manufacturing costs beyond the insights provided by digital simulations
Analysis of the helical torsion spring of the variable diameter
Full text linkV zaključni nalogi je prikazan postopek preračuna vijačne vzvojne vzmeti spremenljivega premera po klasični metodi in po metodi končnih elementov. Pri preračunu po klasični metodi smo predpostavili vzmet kot ukrivljen nosilec v prostoru. Za analizo vzmeti po metodi končnih elementov smo uporabili program Abaqus. Cilj, ki smo ga hoteli doseči, je relacija med povesom vzmeti in silo po obeh metodah ter primerjati dobljene rezultate, če se razlikujejo.In the thesis a procedure of the conversion of the helical torsion spring of variable diameter according to the classical method of the finite elements is shown. In the process of the conversion according to the classical method we assumed the spring as a spatial beam in space in order to calculate torsional and bending moments. For the analysis of the spring according to the method of finite elements we used the program Abaqus. The goal we tried to achieve in the thesis is the obtained relation between the deflection of the spring and the force according to both methods, and to compare the acquired results as well as comment the possible derogations
Calculation of pressure vessel according to ASME standard
Full text linkNamen magistrskega dela je izvesti preračun tlačne posode po standardu ASME na tri načine. Prvi je analitičen preračun po standardu ASME, drugi je preračun s programskim paketom Visual Vessel Design, tretji način pa z metodo končnih elementov. S slednjim smo obravnavali tudi najbolj kritične detajle. Cilj magistrskega dela je primerjava rezultatov, preračunanih po standardu in programskem paketu Visual Vessel Design, ter njegova validacija. Pridobljeni rezultati v osnovi potrjujejo ustreznost programskega paketa, so se pa manjša odstopanja pojavila pri primerjavi preračunov kritičnega detajla s programskim paketom in z metodo končnih elementov. Razlogi za ta odstopanja so v definiranju zvarnih spojev pri preračunu s končnimi elementi, saj ne moremo natančno vedeti, kaj se dogaja z osnovnim materialom v stiku z zvarnim spojem. Dejanska geometrija zvarnega spoja je kompleksna, zato smo ga pri numerični simulaciji poenostavili in ga definirali s trikotno geometrijo v prečnem preseku.The purpose of the master\u27s thesis is to perform a pressure vessel calculation according to the ASME standard in three ways. The first method is an analytical calculation according to the ASME standard, second is with Visual Vessel Design software package, and third method is with the finite element method. The most critical details were also being considerate by the finite element method. The aim of the master\u27s thesis is to compare and validate the results calculated according to the ASME standard and Visual Vessel Design software packages. Calculated results confirm the adequacy of software package. We also compared the results of calculated detail with the Visual Vessel Design software package and with the finite element method shows smaller deviations that result from defining the welds. Since we do not know exactly what is going on with the material in contact with the weld, and the actual geometry of the weld is complex, we used simplification of the weld in the numerical simulation. The weld joint was defined by triangular geometry in cross section
Construction of gear box for roller conditioner for disc mowers
No full textV magistrskem delu je predstavljen proces konstruiranja novega gumijastega gnetilnika za diskaste kosilnice. Opisani so način in namen uporabe gnetilnikov, njihove prednosti in slabosti. Prikazane so trenutne izvedbe gumijastih gnetilnikov z dvema valjema. Izvedena je raziskava trga na področju diskastih kosilnic. Ugotovljene so bile priložnosti za nove rešitve. Opisane so ideje za izboljšave oz. nove rešitve postavitve valjev. Predstavljeni in vrednoteni so koncepti za novo izvedbo gumijastega gnetilnika. Za izbrani koncept (trije valji, gnani z zobniškim gonilom) je opravljeno detajliranje in modeliranje komponent. Prikazan je potek moči od traktorja do grebena in gumijastega gnetilnika. Opisani so proces izračuna oz. določitve geometrije zobnikov (stožčastih in valjastih), preračun medosnih razdalj, dimenzij gredi, izbira ležajev in oblikovanje ohišja. Natančneje je opisana, detajlirana in vrednotena stožčasta zobniška dvojica po standardu SIST ISO 10300. Izvedeno je vrednotenje gredi v gonilu in prikazana celotna zasnova gonila. Cilj znotraj magistrskega dela je bil razviti novo gonilo, ki bo nato izdelano, testirano in v prihodnosti implementirano na kosilnicah z gumijastim gnetilnikom.This thesis describes the process of construction and development of the new roller conditioner for disc mowers. It describes the types and usage of conditioners for disc mowers. The current solutions of roller conditioners with two rollers are shown and described, the thesis also contains analysis of the market and shows new opportunities for upgrades. The ideas for better positioning of rollers are described. Furthermore, new concepts are described and rated. The chosen concept (with three rollers and a gear box) is detailed and models are created. The process of power path from the tractor to the mower is described. This thesis includes the calculation of geometry for spur and bevel gears, calculations of distances between axes, shafts dimensions, construction of housings and bearings. The complete calculation of bevel gears is conducted and described, according to standard SIST ISO 10300. The calculations of shafts and whole design of gear box are included. The goal of this thesis is to develop new gear box, which will be made, implemented and tested on the mowers with roller conditioners
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