Failure analysis of a special vehicle engine connecting rod

This paper presents failure analysis of the connecting rod used in a 12-cylinder diesel engine set on a special vehicle. The fracture of the connecting rod occurred during the engine test in laboratory conditions. Chemical and metallographic analysis as well as mechanical testing have confirmed that the material properties of the connecting rod met the requirements of standard specification and technical documentation. Linear finite element (FE) analysis was performed to evaluate stress state of the connecting rod under maximum load. The results of FE analysis showed that the position of the fracture is consistent with the zone of highest stress. Fractographic analysis has not been able to reveal the main cause of mechanism of fracture due to substantially damaged fracture surface. Inadequate machining, absence of polishing and highest stress in the region of fracture were identified as the main causes of failure. Finally, the engine had been working at maximum load for a longer period of time that also led to the breakage of the connecting rod.This is the peer reviewed version of the paper: Rakić, S. N.; Bugarić, U.; Radisavljević, I.; Bulatović, Ž. Failure Analysis of a Special Vehicle Engine Connecting Rod. Engineering Failure Analysis 2017, 79, 98–109. [https://doi.org/10.1016/j.engfailanal.2017.04.014

Grinding processes and their effects on surface integrity

The introduction of high performance grinding machines in combination with the latest superabrasive technology has the potential to impact significantly on existing process chains. The aim of the research was to look at both the high and low rate removal grinding processes and their effects on the surface integrity, as a means to exploit the above technologies. A major objective was to determine the feasibility of High Efficiency Deep Grinding (HEDG) in cylindrical plunge grinding. HEDG is a high speed removal process which differs from conventional forms of grinding in that it uses large depths of cut together with high feedrates. Together, these changes affect the thermal energy partitioning within the work zone. Through this work an understanding of the process conditions enabled the development of this process, such that prevention of thermal damage to the finished workpiece surface is achievable. At the opposite extreme to the high material removal rates of HEDG, kvdrk was carried out in the high precision finish grinding regime. Developments *ere undertaken to look at the implementation of a modified path into the normal cylindrical plunge grinding action, in a process referred to as Superfinish Grinding. The aim of this process being to demonstrate an improvement to the surface texture primarily through a reduction in grinding directionality. Surface integrity is an important consideration in the development of any grinding process. Damage as a result of grinding is predominately of a thermal nature and results in changes to the material properties in the near surface region. One such change is the residual stress, which was measured using Barkhausen Noise intensity instrumentation, which provided a reliable early indication to a build up in thermal energy. Developments in thermal modelling supported by temperature measurements provided a better understanding of the HEDG regime. The model employed new energy partitioning theories together with circular arc modelling of conditions along the contact length. A model was derived to predict the surface finish produced with the Superfinish Grinding approach, this again provided an increased understanding of the grinding process. Industrial trials have shown how HEDG can be implemented on standard production machine tools for the cylindrical plunge grinding of crankshaft components. The process demonstrated the potential for improved surface integrity, whilst maintaining surface finish and form accuracy. The same grinding machine was also used to generate high quality surfaces using a Superfinish Grinding process. Roughness values of the order of 0.11um RQ were routinely obtained exhibiting reduced levels of grinding directionality. Thus, using a single machine tool and a single set-up, exceptionally high stock removal rates are achievable in a roughing cycle followed by superfinishing to generate the required surface characteristics and profile.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

The wear behaviour of UHMWPE and ion implanted UHMWPE against differing counterfaces

Includes bibliographical references.A study has been made of the tribological behaviour of ultra high molecular weight polyethylene (UHMWPE) and ion implanted UHMWPE during water lubricated reciprocating sliding against differing stainless steel and Yttria Partially Stabilised Zirconia (YPSZ) counterfaces. A new laboratory test apparatus was designed, built and commissioned to facilitate this research. The new apparatus is capable of simulating the reciprocating wear of a sliding couple under diverse conditions of pressure, sliding speed and lubricant environment, as well as allowing the measurement of frictional forces 'encountered between the two surfaces in sliding contact. Variation in stainless steel counterface surface roughness resulted in three different types of wear behaviour

Characterisation of a New Nanostructured Aluminium Alloy and Piston Design for Internal Combustion Engines

The ever growing concerns over toxic engine emissions, sustainability and global warming put the automotive industry under immense pressure to reduce pollution and improve the efficiency of internal combustion engines. The lighter the mass of a vehicle the lower the energy required to propel it and potentially the lower the emissions that will ensue. Also, reducing piston mass affects piston and ring assembly frictional losses and therefore engine efficiency. This trend in the automotive industry motivates desire for new lighter materials such as the nanostructured aluminium alloy used in this research. The aim of this research was to characterise a new nanostructured aluminium alloy and use heat treatment to optimise its mechanical properties for application as a lightweight engine piston material. The hardness of the new alloy at T6 was 35% higher than that corresponding to Al-2618 that is used for the test engine piston in this project. The high temperature tensile tests carried out at piston operating temperature showed that the new alloy had 1.09–1.82 times higher strengths than that of Al-2618 depending on the test temperature. In addition, the new alloy also had higher strengths than other aluminium alloys used in piston applications. The design approach used in this work was to reduce piston mass using topology optimisation without affecting the external envelope and the shape of the combustion chamber. The new piston’s mass was 218.35 grams which was 16.38% lighter than the original piston with mass of 261.13 grams. The final machined piston turned out to be slightly heavier than the final optimised piston design. This was due to the coating and also some modifications needed to make the design machinable. However, the final machined piston was still 13.5% lighter than the original piston. The new piston was more fuel efficient than the original piston at higher speeds and lower torques. At a speed of 3000 rpm, the new piston was on average 2.04% more fuel efficient at all torques values. Overall, the new piston had higher volumetric efficiency compared to the original piston, but at higher engine speed of 6000 rpm and higher torque the new piston had lower volumetric efficiency. To ultimately determine whether the new lightweight piston would generate any sizeable difference in engine performance and/or efficiency across the wider engine running envelope, further work is needed

Historical development of the windmill

Throughout history, windmill technology represented the highest levels of development in those technical fields now referred to as mechanical engineering, civil engineering, and aerodynamics. Key stages are described in the technical development of windmills as prime movers; from antiquity to construction of the well known Smith-Putnam wind turbine generator of the 1940's, which laid the foundation for modern wind turbines. Subjects covered are windmills in ancient times; the vertical axis Persian windmill; the horizontal axis European windmill (including both post mills and tower mills); technology improvements in sails, controls, and analysis; the American farm windmill; the transition from windmills to wind turbines for generating electricity at the end of the 19th century; and wind turbine development in the first half of the 20th century

Experimental Analysis of the Discharge and Flow Coefficients of a Multi­valve Internal Combustion Engine

The search for newer ways to reduce emissions and fossil fuel consumption worldwide has be- come more urgent than ever since climate change was identified as the main challenge of the current century. Internal Combustion Engines (ICEs) are responsible for a large portion of emis- sions and, for this reason, a constant search for engine efficiency improvement has been made. The key to achieve an improved engine performance might be lying in the study of the airflow across the intake system since several factors and phenomena which considerably limit engine breathing and efficiency are identified. Being the major inlet flow restriction, the port-valve assembly plays an important role in allowing the airflow to be drawn into the cylinder. In order to measure how efficient the induction process is, discharge and flow coefficients are defined and investigated under different intake conditions. In this sense, an experimental investigation aiming at the study of the fluid dynamic efficiency of a multi-valve Spark-Ignition (SI) engine during the induction stroke was carried out at the Propulsion laboratory of the University of Beira Interior (UBI). To this purpose, the effect of adding a throttle body to the inlet system and de- activating one inlet valve are analysed under static and dynamic conditions. Four throttle plate angles: 30, 50, 70, and 90º were tested along with an inlet configuration without a throttle plate. The experimental tests were conducted at a steady/unsteady flow rig in terms of dimensionless discharge and flow coefficients, in order to understand if the dynamic performance of the port- valve assembly can be predicted through steady discharge and flow coefficients. Throughout the tests, the pressure drop was kept constant at 13 kPa and the valve lift varied from 0.5 mm to 8.4 mm. During each measurement, the air mass flow, inlet temperature, valve upstream pressure and cylinder pressure are registered. The investigation highlights the influence of valve lift on engine breathing. Moreover, it demonstrates that adding a throttle body into the inlet system will result in reduced engine breathability in comparison to a configuration without a throttle plate. This study also indicates that deactivating one inlet valve, in multi-valve engines, leads to higher discharge coefficients, while the conventional configuration results in higher flow co- efficients. The impact of the camshaft velocity on engine breathing is evaluated in terms of mean discharge and flow coefficients. The research shows that the discharge and flow coeffi- cients decrease slightly as the camshaft velocity increases. Overall, a good agreement between static and dynamic results was achieved, proving that steady coefficients can predict with good accuracy the unsteady behaviour of the intake port and valve.A procura de novas formas de reduzir emissões e o consumo de combustíveis fósseis em todo o mundo tornou-se mais urgente que nunca, uma vez que o principal desafio do século atual é apontado como sendo as alterações climáticas. Os motores de combustão interna são respon- sáveis por grande parte das emissões emitidas e, por este motivo, tem vindo a ser feita uma procura constante a fim de se conseguir obter uma melhor eficiência nos motores. A solução para alcançar um melhor desempenho de motor pode estar no estudo do fluxo de ar a atraves- sar o sistema de admissão uma vez que, através deste estudo, vários fatores e fenómenos que limitam significativamente a respirabilidade do motor, e consequentemente, a sua eficiência são identificados. O conjunto porta-válvula é o local do sistema de admissão que mais restringe o fluxo de ar, deste modo, este desempenha um papel importante ao permitir que o caudal de ar na admissão seja admitido pelo cilindro. A fim de medir a eficiência do processo de indução, coeficientes de descarga e fluxo são definidos e investigados sob diferentes condições de en- trada. Neste sentido, foi realizada uma investigação experimental com o objetivo de estudar a respirabilidade de um motor de ignição por faísca com múltiplas válvulas por cilindro durante o processo de admissão. Este estudo foi realizado no laboratório de Propulsão da Universidade da Beira Interior. Para tal, o efeito de adicionar um corpo de borboleta ao sistema de admis- são e desativar uma válvula de admissão são analisados em condições estáticas e dinâmicas. Foram testados quatro ângulos de acelerador: 30, 50, 70, e 90º, bem como uma configuração sem borboleta de admissão. Os testes experimentais foram conduzidos num banco de ensaios estático/dinâmico em termos de coeficientes de descarga e fluxo adimensionais, a fim de com- preender se o desempenho dinâmico do conjunto porta-válvula pode ser previsto através de coeficientes de descarga e fluxo estáticos. Ao longo dos testes, a queda de pressão foi man- tida constante a 13 kPa e o levantamento da válvula variou entre 0.5 mm a 8.4 mm. Durante cada medição, o caudal de ar, a temperatura de admissão, a pressão a montante da válvula e a pressão a jusante da mesma foram registadas. A investigação realça a influência do levanta- mento da válvula na respirabilidade do motor. Além disso, demonstra que a adição de um corpo de borboleta ao sistema de admissão resulta numa redução da capacidade de admitir ar por parte do motor em comparação à configuração sem borboleta. Este estudo também evidência que a desativação de uma válvula, em motores com duas válvulas de admissão por cilindro, tem como resultado a obtenção de maiores coeficientes de descarga, enquanto que a configuração de duas válvulas resulta em coeficientes de fluxo mais elevados. O impacto da velocidade da árvore de cames na respirabilidade do motor é avaliado em termos de coeficientes de descarga e fluxo médios. Os resultados mostram que os coeficientes de descarga e fluxo diminuem ligeira- mente à medida que a velocidade da árvore de cames aumenta. No geral, foi alcançada uma boa concordância entre os resultados estáticos e os dinâmicos, provando que os coeficientes estáticos podem prever com uma boa precisão o comportamento dinâmico da porta e da válvula de admissão

Development of Electricity Generation and Sensor Systems for a Hydropower Propagating Wave Turbine

The Propagating Wave Turbine Project focused on the design, construction, and verification of an energy generation system that converted shaft rotation into electrical energy. A maximum power point tracking system created the optimal load profile between the voltage and current produced by an electromechanical generator. A sensor system was developed to measure power generator and transformation characteristics. A nacelle was designed and built to hold the components and connect to a Propagating Wave Turbine built by a separate project team. Operation was successful, but the shaft speeds of the wave turbine and generator were not compatible. Recommendations are provided for improvement in energy conversion

Optical access engine development

A partial design for an optical access engine was acquired by the University of Southern Queensland from Oxford University in the UK. It is the desire of USQ or specifically certain faculty members to include an optical access engine in their engines laboratory. The purpose of this research project is to take the existing partial design from the early 1990’s of Professor Richard Stone’s (Oxford University) and develop it into a useable design of which the University can invest in. for their laboratory. Due to time constraints it was not possible for the entire engine to be designed and detail drawings produced so the engine was designed from the bottom end up to the top of the optical bore which on a normal engine is the top of the cylinder block. Included in this dissertation is a report covering the need for engine research and the place of optical access engines in research. A literature review of various optical access engines and discussion of their types and uses. Finally a report covering the methodology of the design and the results of design calculations with a focus on balancing and component design. Detail drawings suitable for workshop manufacture and calculations are included as part of this dissertation as are recommendations for future work