An investigation into hybrid power trains for vehicles with regenerative braking

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Finite element for the analysis of rotor-dynamic systems that include gyroscopic effects

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.This thesis presents new finite element formulations for the analysis of rotor-dynamic systems that include the effects of gyroscopic influence. Euler-Bernoulli finite elements have been created for both shaft and propeller descriptions. In addition to the gyroscopic effects, centrifugal stiffening has been considered for the propeller elements. The principle of virtual work has been used to determine the equations of motion and formulate element matrices. The proposed element matrices have been incorporated in the VIBRATIO suite of vibration analysis software in order to test the formulations. The software uses an innovative hybrid modelling technique that enables the user to analyse various dynamic problems including rotating beam elements with rigid body attachments. A model of a ship's drive shaft has been created in VIBRATIO for comparison against a verified ANSYS model. Results for forced vibration shaft analysis show excellent correlation between VIBRATIO's Euler shaft formulation and ANSYS's Timoshenko formulation. Incremental analyses of propeller systems using the novel gyroscopic formulation show gyroscopic effects of flexible blade attachments, and also the changing mode shapes and frequencies due to centrifugal stiffening. Results show gyroscopic and centrifugal stiffening effects must not be ignored for an accurate propeller analysis.This work was financially supported by Brunel University

Development and experimental validation of a low-frequency dynamic model for a Hybrid Electric Vehicle

This paper describes the development and experimental validation of a high-fidelity Hybrid Electric Vehicle (HEV) simulator that enables testing and calibration of energy management and driveline control strategies. The model is capable of predicting longitudinal vehicle responses that affect energy consumption and drivability in the low-to-mid frequency region (up to 10 Hz). The simulator focuses primarily on the drivetrain dynamics, while the dynamics of the actuators are represented by simplified models. The vehicle simulator is validated by a number of experiments that include electric only, engine only and hybrid operating conditions. The test vehicle has a through-the-road parallel hybrid architecture that utilises a dual electric machine configuration. Experimental results confirm that important driveline phenomena such as shunt, shuffle, torque holes and other transient disturbances related to operating mode changes are accurately predicte

Effect of planetary gearboxes on the dynamics of rotating systems

The coupled dynamic behaviour of planetary geared rotor systems is much less well understood compared to the classical geared rotor systems. For a better understanding, this research project investigates the coupled dynamic behaviour of planetary geared rotor systems and how the planetary gearbox parameters affect their global dynamics. In the numerical study, a six degrees of freedom hybrid dynamic model of a planetary geared rotor system is created in the recently developed “GEAROT” rotor dynamics software by considering gyroscopic effects. Based on the modal analysis results of the hybrid dynamic model, the vibration modes are classified as coupled torsional-axial, lateral and gearbox for the helical gear configuration, and torsional, axial, lateral and gearbox for the spur one. Modal energy analysis is used to quantify the coupling level between the shafts and planetary gearbox, which highlights the effect of a planetary gearbox on the dynamic behaviour of a rotating system. An extensive planetary gearbox parameter study including gear contact, gearbox mass and support, and planet gear parameters is conducted using the hybrid dynamic model to investigate the parameter effects on the modal behaviour of planetary geared rotors. The sensitivity of planetary geared rotor vibration modes to the gearbox parameters is determined by computing the frequency shifts and comparing the mode shapes between the two extreme cases. In the experimental study, free-free impact hammer tests are carried out on a planetary geared rotor assembly to validate the numerical modal analyses results in “GEAROT”. On the basis of both experimental and numerical modal analysis of planetary geared rotors, the lateral vibration modes are identified as “in phase” and “out of phase”. Briefly, the numerically identified lateral modal behaviour of planetary geared rotor systems is successfully validated with the experimental modal analysis results.Open Acces

Production of Hybrid Tubular Metal-Fiber-Preforms: Material Characterization of Braided Hoses with a Binder

Hybrid shafts or rods, where the area of load introduction is metallic (e.g. steel or aluminium) and the area of load transfer is made of fibre reinforced plastics (FRP), are an established concept for lightweight parts. Besides the monolithic FRP and the metallic areas, the overlap area of both materials is particularly important. Such parts can beneficially be produced by the use of liquid composite moulding (LCM), where the bonding process takes place during the resin curing. This is called intrinsic hybridization. Beforehand it is crucial to produce a near-net-shape preform in which the metallic end fittings for the load introduction are already integrated. To manufacture such parts constantly with a high quality, a process model of the joining by draping the braided preform is necessary. In this paper an approach for the production of hybrid preforms made of braided hoses and metallic fittings is presented in order to develop a process model. The process starts with a cylindrical multi-layer preform made of braided hoses, in which the layers are bonded by a thermoplastic binder powder. The decisive process step is the draping of the preform onto the metallic fitting. For this forming step, the material characterization of the hybrid preform plays an important role. Several material tests to determine the textile parameters of the preform are therefore evaluated and performed. Finally, the results of these tests are presented and discussed

Power transmission systems: from traditional to magnetic gearboxes

L'abstract è presente nell'allegato / the abstract is in the attachmen

Combined misalignments in spur gear transmission systems: a semi-empirical approach

Un área inexplorada en el diseño de sistemas de transmisión de engranajes es el estudio de los efectos de desalineamientos combinados en las medidas de vibración. Actualmente, las investigaciones se centran en desalineamientos individuales y no combinados los cuales reflejan mejor los escenarios de aplicaciones reales. En esta investigación se analizan los efectos de los desalineamientos combinados en las mediciones de vibración en la base de los rodamientos y en el esfuerzo de flexión de los dientes de engranajes rectos de un sistema de transmisión de una etapa. Se diseñó y construyó un banco de pruebas para generar desalineamientos radiales, axiales y angulares en un sistema de transmisión de engranajes de una etapa. Se evaluaron todas las combinaciones posibles de niveles extremos de desalineamiento para un par de engranajes rectos para identificar tendencias en la respuesta vibratoria. Se desarrolló un modelo teórico del área de contacto proyectada para estudiar la relación entre esta y la respuesta vibratoria. Al analizar el cambio en los espectros, se determinó la influencia de diferentes desalineamientos y sus interacciones en las mediciones de vibración. Finalmente, se desarrolló un modelo híbrido para estimar las aceleraciones en los rodamientos, utilizando un modelo de elementos finitos para determinar el esfuerzo de flexión en los dientes y un modelo analítico para estimar las señales de vibración en los rodamientos. El modelo demostró una alta correlación en comparación con los resultados experimentales, validando su efectividad. Finalmente, se propusieron recomendaciones de diseño considerando las zonas de esfuerzo y vibración de interés.DoctoradoDoctor en Ingeniería Mecánic

Implementing active force control to reduce vibration of a short length drive shaft

Vibration is a physical phenomenon involving repeated oscillatory movements or fluctuations at certain frequency and typically undesirable in many applications since it may cause undue failure or damage to the system. In this paper, the vibration of a three degree-of-freedom (DOF) model representing a short length drive shaft has been effectively and robustly suppressed through the implementation of a novel Active Force Control (AFC) used in conjunction with a classic proportional-integral-derivative (PID) controller. The shaft vibration caused by its support and constraint during its operation was simulated using MATLAB and Simulink considering a number of operating and loading conditions. The results proved that when a pure PID controller was implemented, the vibration is indeed reduced but at the expense of longer execution time and producing noticeable frequency oscillation with slight offset. On the other hand, when the AFC loop was engaged by adding it directly in series with the PID controller (PID+AFC) to produce a 2 DOF controller without any need to further tune the PID controller gains, the vibration is significantly reduced with the amplitude hovering a zero datum without any offset and yielding an extremely low frequency trending

Torsional Oscillations in Automotive Transmissions: Experimental Analysis and Modelling

The paper investigates the torsional oscillations of an automotive transmission system by means of an experimental test bench used to validate the proposed lumped parameter model. The rig consists of a Dual Clutch Transmission (DCT) and a Manual Transmission (MT) connected through the respective output shafts, while the excitation is provided by two electric motors, which are controlled in speed or torque.The experimental analysis includes the measurement of the external torques, applied by the two electric motors to the mechanical system, and the measurement of the system response in terms of angular speeds at different positions along the transmission line. The frequency response of the system is estimated from the experimental data and compared with the results of a 5-degree-of-freedom lumped parameter model, which proves to be adequate to describe the dynamic behaviour of the system up to a frequency of 200 Hz.The comparison between simulated results and experimental data shows good agreement, so the model can be used to predict the torsional vibrations of the transmission system in the linear field. Moreover, the effects of the nonlinearities associated with the mean value of the excitations are shown. Finally the influence of the selected gear ratio on the experimental frequency response is discussed