Ali Daadbin

Development, testing and implementation of the pantograph damage assessment system (PANDAS)

This paper on the pantograph damage assessment system (PANDA) is from the proceedings of the 12th International Conference on Computer System Design and Operation in Railways and Other Transit Systems, held in Beijing, China, in 2010. The authors remind readers that pantograph failures due to complex interactions between the overhead line (OHL) and pantograph structure cause significant problems to the railway industry worldwide. Then they describe the development, design and test results of the Pantograph Damage Assessment System (PANDA), which is now deployed on routinely operating trains in the United Kingdom. The system uses two subcomponents: the Digital Processing Module (DPM), which is directly clamped on the live 25kV pantograph structure, and the Receiving Signal and Relay Unit (RSRU) which is installed in a secure location inside the carriage. A pantograph mounted unit is interfaced with the accelerometers that are attached in vicinity of the carbon strip. The DPM uses Bluetooth communication to report any unexpected events to the RSRU. Any high alarm events are instantaneously transferred to the train to warn the operator and the control center about a potentially harmful event that requires immediate attention. The ‘hot spots’ caused by the overhead line are mapped and trended to allow successful implementation of predictive maintenance of the OHL. The authors conclude that the PANDA monitoring system reduces maintenance costs for both the pantograph and for the overhead line electrical equipment.

Deformation and fracture, during cooling, of the alumina scale developed on Fe3Al

The deformation and fracture, during cooling, of oxide scales developed on Fe3Al has been modelled using finite element analysis (FEA). Embedded defects were introduced at the oxide surface and at the oxide/substrate interface; the propagation of these defects and the influence of such propagation on scale spallation was analysed under both elastic and elastic plastic conditions. Stress relaxation associated with the plastic deformation of the substrate delayed scale spallation as indicated by the greater temperature drop required to cause spallation. In this situation, the presence of the oxide surface crack influenced scale spallation in a complex manner. The oxide surface crack did not influence the scale spallation process for the linear elastic analysis, which was solely controlled by the interfacial defect.

Performances of AC induction motors with different number of poles in urban electric cars

This paper presents the results of a study on the effect of the number of poles of AC induction motors (IM) on their performance in both propulsion and regenerative brake modes in eco-urban electric cars (EC). Since changing the number of poles affects the maximum motor speed, different transmission ratios are considered in modelling of the powertrain system. Two speed profiles, namely, normal and aggressive, are used in this study. Both profiles are based on the field data of a route in Kayseri-Turkey. For each configuration the total consumed energy of the EC is found. Results show that IM with 4 poles performs better than other configurations with respect to the cost and energy efficiency.

Effect of laminate configuration and shell-thickness variation on the inducted twist distribution in wind turbine adaptive blades

This paper presents an analytical model for predicting the dynamic characteristics of composite wind turbine blades. In this model, the governing equations of motion are derived using Hamiltions principle and are solved by using extended Galerkins method. This model is capable of predicting natural frequencies of composite beams with arbitrary single-cell cross sections. For various layup configurations, the results obtained by the developed analytical model are compared with the results of the finite element analysis. It is shown that the analytical model provides reasonable accuracy in predicting natural frequency of unbalanced layup configurations with ply angles of up to 40 degrees.

A comparative study of the performance of DC permanent magnet and AC induction motors in urban electric cars

This paper presents a comparative study of the performance of two types of electric motors used in eco-urban electric cars (EC). The power transmission system of an EC is modelled once with a DC permanent magnet (PM) and once with an AC induction motor (IM). In both cases the electric motors can operate in two modes: propulsion mode (motor) and regenerative brake mode (generator). Two standard velocity history profiles SFUDS and ECE-15 are used to model the dynamic of the car. It is shown that IM performs more effective than PM.

Online monitoring of essential components helps urban transport management and increases the safety of rail transport

Complex modern transport systems need to be reliable and operated at high efficiency with the cost of breakdowns kept at a minimum. The well known strategy for maintaining the operation of any integrated system is to choose the appropriate parameters to be monitored continuously. Then, any fault or deviation from the normal operation condition would be detected and the necessary action could be taken to avoid any disruption to the operation and avoid any accident with devastating consequences. This paper looks at monitoring of parameters for essential components in rail transport such as axle vibration and pantograph load, and gives the detail of the systems used in monitoring their operation. The continuously measured data such as torque on the main gearbox shaft or load/acceleration on the pantograph enables diagnosis of potential issues within such systems on routinely operating trains. Variations from the expected values can be detected early and corrected to avoid compromising passenger safety from a more severe failure in the future. The paper discusses the system designed for monitoring the transmitted torque and bending moments in the rail vehicle axle as a mean for identification of any abnormal loading. Pantograph failures due to complex interactions between the overhead line (OHL) and pantograph structure cause significant problems to railway industry worldwide. This paper also describes the design, development and test results from the first fully proven Pantograph Monitoring System which is now deployed on routinely operating trains in the UK.

An analytical model for deformation analysis of wind turbine adaptive blades

Abstract An analytical model capable of predicting the induced deformation due to the presence of bend-twist and stretch-twist elastic couplings in multi-cell closed thin walled beams with arbitrary cross-sections is presented. For various structural and material configurations, the results obtained by the developed model are compared with the results of the finite element analysis. It is shown that the developed analytical model provides reasonable accuracy in predicting induced twist. The developed model is implemented in an aero-structure simulation environment for simulation of wind turbines utilising adaptive blades. Keywords: thin-walled beam, multi-cell closed thin walled beams, adaptive blades, elastic coupling, bending-twist coupling, wind turbine composite blade 1 Introduction Fibrous composite materials have been broadly used in aeronautical and aerospace structures due to their proven advantages, such as high strength-weight ratios. One particular application of these materials is in fabricating smart and adaptive aerodynamic lifting surfaces such as wind turbine adaptive blades and aircraft smart wings. An adaptive blade acts as an open-loop controller that senses the wind velocity or rotor speed variations and adjusts its aerodynamic characteristics accordingly to improve the wind turbine performance. This self-control system can be achieved by implementing elastic coupling in the structure of the blade. In order to determine the aerodynamic performance of adaptive blades at various loading conditions, a structural analyser is required to calculate the induced deformation of the blade. Figure (1) shows the simulation environment for wind turbines utilising this type of blades. Torsional deformation of an adaptive blade is the key parameter influencing the wind turbine aerodynamic performance. The accuracy of the predicted torsional deformation is crucial in simulation and design of adaptive blades [1, 2]. A number of analytical models of anisotropic thin-walled beams have been proposed for box beams. Most of researchers employed strain energy and virtual work methods to study the static and dynamic characteristic of thin- and thick-walled beams. Chandra et al. [3] and Kim and White [4] developed analytical models for circumferentially asymmetric stiffness (CAS) and circumferentially uniform stiffness (CUS) for single-cell box beams. They considered the bending, torsional and extensional loads and included shear and warping effects. Their model was, however, limited to rectangular cross-sections. Wu et al. [5]

An investigation into using finite element analysis for epoxy resin joints

Finite element analysis (FEA) is a well-established tool for the study of engineering components, but designs often involve the use of materials that are bonded together using adhesives. The accuracy of using linear elastic FEA to model epoxy/aluminium bonds is investigated by the comparison of actual results with computer-predicted data. From the results obtained it is shown that it is possible to model epoxy resin joints, provided that careful mesh refinement is used in the interface region so that the effect of nodal stress averaging is overcome. The FE models were then used to study failure modes and it was established that both elastic or plastic failure of the joints can occur depending on the magnitude of any interface stress concentrations present.

An analytical model for frequency analysis of composite wind turbine blades

This paper presents an analytical model for predicting the dynamic characteristics of composite wind turbine blades. In this model, the governing equations of motion are derived using Hamiltions principle and are solved by using extended Galerkins method. This model is capable of predicting natural frequencies of composite beams with arbitrary single-cell cross sections. For various layup configurations, the results obtained by the developed analytical model are compared with the results of the finite element analysis. It is shown that the analytical model provides reasonable accuracy in predicting natural frequency of unbalanced layup configurations with ply angles of up to 40 degrees.

Modal Analysis of a Thin Plate: A Demonstration Package for Undergraduate Students

This paper reports on a demonstration package that gives students a clear understanding of the vibration and modal analysis technique, which forms a crucial theme in dynamics and vibration analysis and condition monitoring. A rig has been prepared to display the experimental results and give the students hand-on experience. A finite-element (FE) analysis is used to calculate the theoretical results for comparison with those obtained through experiment. The students are then in a position to vary the parameters of the FE analysis model and note the changes in the shift of the natural frequencies.