This chapter reviews recent work done on fuel cells with a focus on PEM fuel cells and their fund... more This chapter reviews recent work done on fuel cells with a focus on PEM fuel cells and their fundamental components. The review process is divided into: design related and those dealt with control and monitoring methods. Achievements, shortfalls and remaining tasks for future investigations are also outlined throughout this chapter.
Mechanical Systems and Signal Processing, Feb 1, 2008
A numerical simulation of a two-stage reciprocating compressor has replicated the operations of t... more A numerical simulation of a two-stage reciprocating compressor has replicated the operations of the compressor under various conditions for the development of diagnostic features for predictive condition monitoring. The simulation involves the development of a mathematical model of five different physical processes: speed–torque characteristics of an induction motor, cylinder pressure variation, crankshaft rotational motion, flow characteristics through valves and vibration
A wind turbine is subjected to a regime of varying loads. For example, each rotor revolution cau... more A wind turbine is subjected to a regime of varying loads. For example, each rotor revolution causes a complete gravity stress reversal in the low-speed shaft, and there are varying stresses from the out-of-plane loading cycle due to fluctuating wind load. Consequently, wind turbine blade design is governed by fatigue rather than ultimate load considerations. Previous studies have adopted many different beam theories, using different techniques and codes, to model the National Renewable Energy Laboratory (NREL) 5 MW offshore wind turbine blade. There are differences, from study to study, in the free vibration results and the dynamic response. The contribution of this study is to apply the code written by the authors to the different beam theories used with the aim of comparing the different beam theories presented in the literature and that developed by the authors. This paper reports the investigation of the effects of deformation parameters on the dynamic characteristics of the NR...
Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy
The harsh weather conditions offshore wind turbine blades are working under have necessitated the... more The harsh weather conditions offshore wind turbine blades are working under have necessitated the need for a more effective approach for detecting their failures. Dynamic characteristics e.g., vibration, carry useful information related to blades structural health. Critical analysis of the blade’s free vibration represents one of the fundamental steps for assessing structural dynamics. When a rotating blade deflects, either in the plane of rotation or perpendicular to it, the centrifugal force exerts inertia force along the blade span, which increases the blade’s natural frequencies compared with the stationary ones. However, the influence of different blade parameters on the flap-wise vibrations is not very well understood. In this paper, the effects of such parameters on dynamic characteristics of National Renewable Energy Laboratory (NREL) 5-MW wind turbine blades are investigated using different beam theories. The examined models have been used to determine the natural frequenci...
2020 13th International Conference on Developments in eSystems Engineering (DeSE), 2020
Gearbox is an important power transmission component in a wide range of industrial applications. ... more Gearbox is an important power transmission component in a wide range of industrial applications. Wear is a common failure mode induced between the contact surfaces of the engaged gear teeth, which result in higher vibration and noise in the gearbox. The early detection of wear is very important for reliable working and better operational performance. Monitoring of gear vibration signature can develop early detection and accurate diagnosis of gear wear fault, and thereby extend the life span of the transmission system. This study focuses on applying an early detection of gear wear that was naturally produced in industrial gearbox system. An experiment gearbox test comprises of back to back two-stage helical gearboxes has been used, where vibration signal was measured and analysed to monitor the health condition of the attached gearboxes under different operation circumstances. Time synchronous averaging (TSA) and wavelet bicoherance (WBC) methods have been used to identify the nonlinearity effect due to induced wear between the contact tooth surfaces. The used methods have the capability to characterize the nonstationary signal and detect the wear at early stages.
A cohesive zone model for delamination propagation in laminated composites under static and fatig... more A cohesive zone model for delamination propagation in laminated composites under static and fatigue loading has been derived and validated with experimental data under different mode conditions. This study presents a new approach to quantify fatigue delamination degradation based on damage mechanics to evaluate the rate of fatigue damage ([Formula: see text]). The static damage evaluation and fatigue damage degradation are derived from damage surface concept. Both static and fatigue damage linked each other to establish fatigue crack growth formula in the laminated composites. A user-defined subroutine, UMAT, has been employed to develop and implement a damage model in ABAQUS. Two different specimens; a double cantilever beam and a single lap joint were used to investigate the effectiveness of the new method. The simulation results revealed that the developed model had good agreement with experimental data available in literature.
This chapter reviews recent work done on fuel cells with a focus on PEM fuel cells and their fund... more This chapter reviews recent work done on fuel cells with a focus on PEM fuel cells and their fundamental components. The review process is divided into: design related and those dealt with control and monitoring methods. Achievements, shortfalls and remaining tasks for future investigations are also outlined throughout this chapter.
Mechanical Systems and Signal Processing, Feb 1, 2008
A numerical simulation of a two-stage reciprocating compressor has replicated the operations of t... more A numerical simulation of a two-stage reciprocating compressor has replicated the operations of the compressor under various conditions for the development of diagnostic features for predictive condition monitoring. The simulation involves the development of a mathematical model of five different physical processes: speed–torque characteristics of an induction motor, cylinder pressure variation, crankshaft rotational motion, flow characteristics through valves and vibration
A wind turbine is subjected to a regime of varying loads. For example, each rotor revolution cau... more A wind turbine is subjected to a regime of varying loads. For example, each rotor revolution causes a complete gravity stress reversal in the low-speed shaft, and there are varying stresses from the out-of-plane loading cycle due to fluctuating wind load. Consequently, wind turbine blade design is governed by fatigue rather than ultimate load considerations. Previous studies have adopted many different beam theories, using different techniques and codes, to model the National Renewable Energy Laboratory (NREL) 5 MW offshore wind turbine blade. There are differences, from study to study, in the free vibration results and the dynamic response. The contribution of this study is to apply the code written by the authors to the different beam theories used with the aim of comparing the different beam theories presented in the literature and that developed by the authors. This paper reports the investigation of the effects of deformation parameters on the dynamic characteristics of the NR...
Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy
The harsh weather conditions offshore wind turbine blades are working under have necessitated the... more The harsh weather conditions offshore wind turbine blades are working under have necessitated the need for a more effective approach for detecting their failures. Dynamic characteristics e.g., vibration, carry useful information related to blades structural health. Critical analysis of the blade’s free vibration represents one of the fundamental steps for assessing structural dynamics. When a rotating blade deflects, either in the plane of rotation or perpendicular to it, the centrifugal force exerts inertia force along the blade span, which increases the blade’s natural frequencies compared with the stationary ones. However, the influence of different blade parameters on the flap-wise vibrations is not very well understood. In this paper, the effects of such parameters on dynamic characteristics of National Renewable Energy Laboratory (NREL) 5-MW wind turbine blades are investigated using different beam theories. The examined models have been used to determine the natural frequenci...
2020 13th International Conference on Developments in eSystems Engineering (DeSE), 2020
Gearbox is an important power transmission component in a wide range of industrial applications. ... more Gearbox is an important power transmission component in a wide range of industrial applications. Wear is a common failure mode induced between the contact surfaces of the engaged gear teeth, which result in higher vibration and noise in the gearbox. The early detection of wear is very important for reliable working and better operational performance. Monitoring of gear vibration signature can develop early detection and accurate diagnosis of gear wear fault, and thereby extend the life span of the transmission system. This study focuses on applying an early detection of gear wear that was naturally produced in industrial gearbox system. An experiment gearbox test comprises of back to back two-stage helical gearboxes has been used, where vibration signal was measured and analysed to monitor the health condition of the attached gearboxes under different operation circumstances. Time synchronous averaging (TSA) and wavelet bicoherance (WBC) methods have been used to identify the nonlinearity effect due to induced wear between the contact tooth surfaces. The used methods have the capability to characterize the nonstationary signal and detect the wear at early stages.
A cohesive zone model for delamination propagation in laminated composites under static and fatig... more A cohesive zone model for delamination propagation in laminated composites under static and fatigue loading has been derived and validated with experimental data under different mode conditions. This study presents a new approach to quantify fatigue delamination degradation based on damage mechanics to evaluate the rate of fatigue damage ([Formula: see text]). The static damage evaluation and fatigue damage degradation are derived from damage surface concept. Both static and fatigue damage linked each other to establish fatigue crack growth formula in the laminated composites. A user-defined subroutine, UMAT, has been employed to develop and implement a damage model in ABAQUS. Two different specimens; a double cantilever beam and a single lap joint were used to investigate the effectiveness of the new method. The simulation results revealed that the developed model had good agreement with experimental data available in literature.
Uploads