The present diploma thesis deals with innovation of built-up crankshaft of Blata minibikes. Minibike is the type of a small two-stroke motorcycle equipped with an internal combustion engine of the volume 40 or 50 cm3. The machine is designed for racing circuits; not only for young riders but also for seniors. The innovation is in the design and verification of pressed connections in the imposition of major pins in the arms of the crankshaft. Pressed connections are designed on the basis of the analysis of force interaction on the crankshaft at maximum revolutions. The proposed solutions are verified by FEM calculations. Based on the results, the best option is selected. For the selected option, the impact of force interaction at maximum machine performance is studied. Finally, on the basis of these facts, designing, technological and economic analysis of feasibility of new production technology is carried out.

Tato diplomová práce uvádí dynamiku klikového mechanismu šestiválcového řadového motoru za účelem návrhu klikového hřídele v CAD programu Pro/Engineer. Následuje popis vibrací klikového mechanismu a analytický výpočet jeho torzních vibrací. Hlavní část diplomové práce se pak zabývá konverzí hřídele do konečno-prvkového modelu v programu ANSYS a jeho importem do prostředí Adams/Engine. V tom je provedena modální analýza klikového ústrojí pro získání vlastních frekvencí a tvarů. Na konec práce je porovnán výstup z analytického řešení a výsledky z multi-body systému.

This master’s thesis focuses on hydrodynamic plain bearing drivetrain in-line sixcylinder diesel tractor engine. In the first part is used as reported in contemporary bearing materials and design solutions bearing basins. Furthermore, given the general Reynolds equation of hydrodynamic lubrication. The main part of the thesis is devoted to creating a virtual model of the crank mechanism in MBS system ADAMS/Engine. Rigid crankshaft in this model is replaced by the flexible crankshaft, which is prepared in the FEM software ANSYS and then exported. The final section presents the results of simulations and their evaluation.

Diploma thesis deals with design of crankshaft for two stroke opposed piston diesel engine. In the theoretical research part a history, comparison with competitive engines in nowadays light aircrafts and the advantages of opposed piston engines are mentioned. In the practical part the balancing is chosen and CAD model of crankshaft is designed. Geometry of this model is than checked for fatigue damage fallout. In the final part was chosen the propeller and appropriate reduction gearbox.

This diploma thesis is focused on solve of design solutions for piston for turbocharged version of Honda K20A engine, especially on reduce of side force acting on piston. There are mentioned methods and on their basis also design solutions for piston to reduce this force. There is also included kinematic and dynamic analysis for each solution and as well their FEM analysis for testing the suitability of these solutions.

This document describes the possibilities of increasing the mechanical efficiency of the crank train of an internal-combustion engine. For this purpose, a concept with a reduced number of main bearings is chosen and its contribution is verified experimentally. The proposed solution consists of an innovative crankshaft design of a four-cylinder spark-ignition engine with only three main journal bearings and laser-welded sheet metal crank webs. The new design is compared to the mass-produced one in terms of friction losses, vibrations and loading of engine parts by means of simulations of crank train dynamics using the Multi-Body System. The increase in vibration, accompanied by a reduction in friction losses, is compensated by a torsional vibration damper and its effect is experimentally verified. Experimental research of laser welds on the crankshaft in terms of fatigue life is also described. The overall potential is also summarised and further possible development of this innovative and patented design is outlined.

[pt] Critérios de fadiga multiaxial para vida infinita tinham por objetivo apenas avaliar a ocorrência de fratura em um componente mecânico quando submetido a carregamentos multiaxiais totalmente reversíveis. Carpinteri e Spagnoli propuseram uma modificação em seu próprio modelo, substituindo por outros parâmetros os limites de resistência à fadiga em flexão f−1 e torção t−1 para ensaios totalmente reversíveis, introduzindo na equação uma variável nf que permitiu realizar uma previsão de vida em fadiga finita. O objetivo do presente estudo é verificar experimentalmente a consistência dessa modificação. A metodologia consistiu em obter experimentalmente curvas de Wohler para tração e torção referentes ao aço DIN 42CrMo4 a fim de obter os parâmetros m e m(asterisco), que são os coeficientes angulares das mesmas em escala log-log, produzindo meios para a aplicação do critério. Como o equacionamento do modelo não apresenta solução analítica, foi desenvolvido uma solução numérica para obter junto ao critério uma previsão teórica de vida em fadiga. Adicionalmente, o estudo busca discutir acerca de uma possível relação direta entre amplitude de tensão normal, amplitude de tensão cisalhante e número de ciclos para falha. O modelo em si apresentou consistência parcial com os experimentos, tendo sido assertivo nos ensaios de torção pura, mas discrepante em ensaios de tração pura. Para carregamentos combinados, houve razoável precisão em dois casos e grande dispersão em outra, mas a avaliação final depende de mais pontos experimentais. / [en] Infinite-life multiaxial fatigue criteria had only the ability to evaluate whether or not fatigue failure is to occur to a mechanical componente once subjected to multiaxial fatigue loadings. Carpinteri e Spagnoli proposed a modification to their own model, substituting both fully reversed bending and torsion fatigue endurance limits, f1 and t−1 respectively, introducing into the equation a new variable nf, allowing the model to predict the fatigue-life of the mechanical component. The main goal of the presente study is to assess the accuracy of the modified model via experiments. The research methodology consisted in determining m and m (asterisk), which are the slopes of the S-N curves for fully reversed bending and torsion experiments on regards to DIN 42CrMo4 steel when plotted into a log-log scale, providing means to apply the model. Since there is no analytic solution to the model, the criterion s equation has to be solved numerically. Furthermore, the present study discusses the possibility of a direct relation between amplitude of normal stress, amplitude of shear stress and number of cycles to failure. The modified Carpinteri & Spagnoli s criterion proved itself to be partially consistent, presenting both accurate predictions of torsional fatigue-life and discrepant results for axial loadings. For combined loadings, the model provided two consistent results while another experimental point was proved far off. The final assessment on regards to the model s accuracy depends on more experimental points.

Sustainability is a major focus for the industry considering the awareness among the public and legislators due to climate change. Automotive manufacturers use many steel products for assembly of vehicles and, many of these products; particularly the heavy and critical components like Front Axle beams and Crankshafts are manufactured using forging process. Due to increased awareness and regulations, all companies are expected to provide environmental impact data relevant to their products. Nonetheless, providing environmental impact data is not yet a common practice in the manufacturing industry, specifically in case of the forged products. Therefore, this thesis aims to establish a comprehensive study of environmental impacts of products namely Heavy vehicle Front Axle Beams, Heavy vehicle Crankshafts, Passenger car Crankshafts and Heavy vehicle steering arms forged at Bharat Forge Kilsta AB and create a baseline for current impact calculations as well as highlight areas for improvement in the future. Lifecycle Assessment (LCA) is used as the method to study the environmental impacts of the forged products. The LCA method in this case is based on ISO 14044 and ILCD Handbook and the impact assessment methods used are EPD (2018) and Cumulative Energy Demand (LHV) v1.0 in accordance with EPD International’s requirements. This research finds that steel and the electricity used in the forging process are the major causes of environmental impacts. To ensure high accuracy of the results of this study, primary data for both steel and electricity is used in the analysis. The LCA results will be published in the form of Environmental Product Declaration (EPD). The CO2 footprint for an average product was found to be 0.89 kg CO2 / kg forged product. Previous studies have utilised average datasets for calculating environmental impacts of forged products which reduce the accuracy of the results. This study, due to the inclusion of primary data of steel manufacturing and electricity generation, provides highly accurate environmental impact results of forged products. / Hållbarhet är ett stort fokus för branschen med tanke på medvetenheten hos lagstiftare och allmänheten på grund av klimatförändringar. Biltillverkare använder många stålprodukter för montering av fordon och många av dessa produkter; speciellt de tunga och kritiska komponenterna som framaxelbalkar och vevaxlar tillverkas med hjälp av smidesprocess. På grund av ökad medvetenhet och bestämmelser förväntas alla företag tillhandahålla data på miljöpåverkan som är relevanta för sina produkter. Icke desto mindre är det ännu inte vanligt att tillhandahålla miljöpåverkansdata inom tillverkningsindustrin, särskilt när det gäller smidesprodukter. Därför syftar denna avhandling till att upprätta en omfattande studie av miljöpåverkan från produkter, specifikt framaxelbalkar för tunga fordon, vevaxlar för tunga fordon, vevaxlar för personbilar och styrarmar för tunga fordon smidda hos Bharat Forge Kilsta AB och skapa en bas för aktuella påverkansberäkningar och för att belysa framtida förbättringsområden. Lifecycle Assessment (LCA) används som metod för att studera de smidda produkternas miljöpåverkan. LCA-metoden i detta fall är baserad på ISO 14044 och ILCD Handbook och de konsekvensbedömningsmetoder som används är EPD (2018)och Cumulative Energy Demand (LHV) v1.0 i enlighet med krav från EPD International. Denna forskning visar att stål och elektricitet som används i smidesprocessen är de främsta orsakerna till miljöpåverkan. För att säkerställa hög noggrannhet av resultaten av denna studie används primärdata för både stål och el i analysen. LCA resultaten kommer att publiceras i form av Environmental Product Declaration (EPD). CO2-avtrycket för en genomsnittlig produkt visade sig vara 0,89 kg CO2/kgsmidd produkt. Tidigare studier har använt genomsnittliga datamängder för att beräkna miljöpåverkan från smidda produkter som minskar noggrannheten i resultaten. Denna studie, på grund av inkluderingen av primärdata för ståltillverkning och elproduktion, ger mycket exakta miljöpåverkansresultat av smidda produkter.

[pt] O presente trabalho se baseia na teoria dos defeitos equivalentes, também conhecida como teoria de Murakami, que permite a predição da vida-fadiga de materiais estruturais adotando o parâmetro (raiz quadrada de area), responsável por uma equivalência quantitativa entre heterogeneidades microestruturais (inclusões metalúrgicas) existentes na região de análise do material e descontinuidades mecânicas (furos) usinados nos corpos de prova. Neste contexto, a tese propõe novas equações, a partir da teoria de Murakami, para prever falhas por fadiga em carregamentos ultralongos (fadiga de altíssimo ciclo, VHCF) do aço DIN42CrMo4, de larga aplicação na fabricação de eixos virabrequins para unidades geradoras de usinas termoelétricas. Corpos de prova do aço DIN42CrMo4 foram usinados com furos de diâmetros variando entre 0,18 mm e 0,70 mm e ensaiados num regime de fadiga de altíssimo ciclo, variando o valor da amplitude de tensão do ensaio, para assim determinar em quais condições o material falha e obter a curva experimental S-N do aço DIN42CrMo4 na presença de diferentes tamanhos de defeitos (furos). Os resultados experimentais permitiram o desenvolvimento de equações em função do parâmetro e curvas de Wohler do material, em conformidade com diferentes descontinuidades mecânicas nos corpos de prova e resistências à fadiga do material. Consequentemente, se estabeleceu uma metodologia que permite uma correlação entre inclusões metalúrgicas, tensão aplicada e vida superlonga em fadiga de eixos virabrequins em serviço em usinas termoelétricas. / [en] The present work is based on the theory of equivalent defects, also known as Murakami s theory, which allows the prediction of the fatigue life of structural materials by adopting the parameter (square root of area), responsible for a quantitative equivalence between microstructural heterogeneities (metallurgical inclusions) existing in the region analysis of the material and mechanical discontinuities (holes) machined in the specimens. In this context, the thesis proposes new equations, based on Murakami s theory, to predict fatigue failures in ultralong loads (very high cycle fatigue, VHCF) of DIN42CrMo4 steel, widely used in the manufacture of crankshafts for generating units of thermoelectric power plants. DIN42CrMo4 steel specimens were machined with holes with diameters varying between 018 mm and 0.70 mm and tested in a very high cycle fatigue regime, varying the value of the test stress amplitude, to determine under what conditions the material failure and obtain the experimental S-N curve of DIN42CrMo4 steel in the presence of different sizes of defects (holes). The experimental results allowed the development of equations as a function of the parameter and Wohler curves of the material, in accordance with different mechanical discontinuities in the test specimens and resistance to fatigue of the material. Consequently, a methodology was established that allows a correlation between metallurgical inclusions, applied stress and super-long fatigue life of crankshafts in service in thermoelectric power plants.

[pt] Uma relação direta onde a vida em fadiga Número de ciclos por falha pode ser descrita como função das amplitudes macroscópicas de tensão normal e cisalhante, Amplitude de tensão normal macroscópica e Amplitude macroscópica da tensão de cisalhamento, é obtida. Utilizando o critério de Carpinteri e Spagnoli (CeS) como uma ferramenta de inspeção, foram obtidas curvas de nível elípticas sobre um domínio Amplitude de tensão normal macroscópica x Amplitude macroscópica da tensão de cisalhamento. A expressão das curvas de nível obtidas foi generalizada, proporcionando uma ferramenta capaz de prever o número de ciclos para falha associado a qualquer combinação (Amplitude de tensão normal macroscópica, Amplitude macroscópica da tensão de cisalhamento). As previsões obtidas através do método da curva elíptica foram comparadas às observações experimentais, bem como a previsões obtidas a partir de versões adaptadas de modelos consagrados na literatura, a saber: Findley (F), Matake (M), McDiarmid (McD), Susmel e Lazzarin (SeL), Carpinteri e Spagnoli (CeS) e Papadopoulos (P). O modelo proposto forneceu previsões em boa concordância com as observações experimentais, e sua capacidade de avaliar o comportamento em fadiga se revelou o melhor dentro todos os critérios considerados. Por fim, uma leve tendência conservadora do modelo foi atenuada através da introdução de um parâmetro de ajuste, melhorando ainda mais sua capacidade de avaliação de comportamento em fadiga. / [en] A direct relation where fatigue life Number of cycles to failure can be determined as function of macroscopic normal and shear stress amplitudes Macroscopic normal stress amplitude and Macroscopic shear stress amplitude is established. Using the Carpinteri and Spagnoli (CandS) criterion as a survey tool, elliptical level curves in the Macroscopic normal stress amplitude x Macroscopic shear stress amplitude domain were revealed and further generalised, providing means to determine the number of cycles to failure for any given (Macroscopic normal stress amplitude, Macroscopic shear stress amplitude ) combination. Predictions obtained through the elliptical curve method (E) were compared to experimental observations, as well as to predictions obtained from adapted versions of popular fatigue criteria, namely Findley (F), Matake (M), McDiarmid (McD), Susmel and Lazzarin (SandL), Carpinteri and Spagnoli (CandS) and Papadopoulos (P). The proposed model delivered predictions in fair agreement with experimental observations and its predictive capability was seen to be the best among all the considered criteria. Finally, a slight bias towards conservativeness was attenuated with the introduction of an adjusting parameter, further improving the predictive capability of the model.