Proceedings of the Institution of Mechanical Engineers,Part C: Journal of Mechanical Engineering Science

Bending analysis of moderately thick laminated conical panels with various boundary conditions is presented using the generalized differential quadrature (GDQ) method. Different combinations of clamped, simply supported, and free boundary conditions are considered. General lay up of laminates including symmetric and asymmetric panels is considered. Assuming the effects of shear deformation and initial curvature, the governing partial differential equations (PDEs) of the problem consist of 15 first-order PDEs in terms of unknown displacements, rotations, moments, and forces. Solution domain, governing equations and related boundary conditions are then discretized based on the GDQ technique. Results revealed that convergence of the method is very fast as it provides reasonably accurate results with a relatively small number of grid points. It is also demonstrated that a similar formulation and solution technique can be used to obtain predictions for sector plates by assuming appropriate geometrical parameters. Comparison of the predictions with results of other analytical and numerical methods shows very good agreement. Further results for symmetric and asymmetric laminated conical panels with various boundary conditions are also presented and validated using the commercial finite-element code ABAQUS for future references.

This article presents driving features analysis in order to determine superior driving features for driving conditions clustering. At first, data gathering is performed in real traffic conditions using advance vehicle location systems. Then driving data segmentation is performed and 21 driving features are defined for each driving segment. After driving feature extraction, the dependency between driving features is investigated. Influence of driving features on vehicle's fuel consumption and exhaust emissions is then studied using computer simulations. The simulation results are then verified by an experimental test. Two types of vehicles, a conventional vehicle and a hybrid electric vehicle (HEV), are simulated. Finally, the most effective driving features are determined. Two superior driving features, ‘energy’ and ‘idle time percentage’, are then used for driving segments clustering. Driving segments clustering may be utilized for driving cycle development, intelligent HEV control, etc.

Multiple pinion drives, parallel arrangements of the pinions for large torque transmission, are widely utilized in various heavy-duty industrial applications. For such multi-mesh gear systems, periodic mesh stiffnesses could possibly cause parametric instabilities and server vibrations. Based on the Floquet–Lyapunov theory, numerical simulations are conducted to determine the parametric instability status. For rectangular waveforms assumption of the mesh stiffness variations, the primary, secondary, and combination instabilities of the multiple pinion drives are studied. The effects of mesh stiffness parameters, including mesh frequencies, stiffness variation amplitudes, and mesh phasing, on these instabilities are yielded. Unstable regions are also indicated for different gear pair configurations. Instability conditions of three-pinion drives are obtained and compared with those of the three-stage gear train.

This article analyses the dynamic behaviour of a beam structure containing multiple transverse cracks using neural network controller. The first three natural frequencies and mode shapes have been calculated using theoretical, finite-element, and experimental analysis for the cracked and un-cracked beam. Comparisons of the results among theoretical, finite-element, and experimental analysis have also been presented. The calculated vibration signatures were used to train the feed-forward multi-layered neural network controller with back-propagation technique for the prediction of cracks. Relative crack locations and relative crack depths are the output of the neural controller. Results obtained from the various analyses are validated using the developed experimental set-up. Results from neural controller have been presented for comparison with the output from theoretical, finite-element, and experimental analysis. From the evaluation of the performance of the neural network controller it is observed that the developed method can be used as a crack diagnostic tool in the domain of dynamically vibrating structures.

This article studies the non-linear dynamic behaviour of a disc brake system during squealing induced by a disc doublet mode. The disc brake system is modelled as a rotating annular plate in contact with annular sector-friction material. In order to investigate the possibility of detachment over the contact area between the disc surface and friction material during squealing, the lift-off condition is applied to this model. Also, the non-linearity arising from the contact stiffness is considered on the basis of the load–deflection test for the friction material. Numerical results show that the vibration after the onset of squeal reaches the limit cycle. In the steady-squealing response, several interesting phenomena are observed: the stick-slip and lift-off over the specific regime of the contact area. It is shown that the dynamic surface pattern rotates due to the forward travelling wave of the squealing surface. However, the mark of the surface pattern does not seem to move because the speed of the travelling wave fluctuates at a double frequency of squeal vibration.

A mathematical model of a railway carriage moving on tangent tracks is constructed by deriving the equations of motion concern the model in which single-point and two-point wheel–rail contacts are considered. The presented railway carriage model comprises front and rear simple conventional bogies with two leading and trailing wheelsets attached to each bogie. The railway carriage is modeled using 31 degrees of freedom which govern vertical displacement, lateral displacement, roll angle, and yaw angle dynamic response of wheelset, whereas vertical displacement, lateral displacement, roll angle, pitch angle, and yaw angle dynamic response carbody and each of the two bogies were also studied. Linear stiffness and damping parameters of longitudinal, lateral, and vertical primary and secondary suspensions are provided to the railway carriage model. Combination of linear Kalker’s theory and non-linear Heuristic model is adopted to calculate the creep forces introduced at wheel and rail contact patch area. Computer-aided simulation is constructed to solve the governing differential equations of the mathematical model using Runge–Kutta fourth-order method. Principle of limit cycle and phase plane approach is applied to realize the stability and evaluate the concerning critical hunting velocity at which the railway carriage starts to hunt. The numerical simulation model is used to study the influence of vertical secondary suspension spring stiffness on the ride passenger comfort of railway carbody at speeds below and at critical hunting velocity. High magnitudes of vertical secondary spring stiffness suspension introduce undesirable roll and yaw dynamic responses in which affect ride passenger comfort at critical hunting velocity.

In this article, explicit expressions for the frequency equation, mode shapes, and orthogonality of the mode shapes of a Single Flexible-link Flexible-joint manipulator (SFF) are presented. These explicit expressions are derived in terms of non-dimensional parameters which make them suitable for a sensitivity study; sensitivity study addresses the degree of dependence of the system’s characteristics to each of the parameters. The SFF carries a payload which has both mass and mass moment of inertia. Hence, the closed-form expressions incorporate the effect of payload mass and its mass moment of inertia, that is, the payload mass and its size. To check the accuracy of the derived analytical expressions, the results from these analytical expressions were compared with those obtained from the finite element method. These comparisons showed excellent agreement. By using the closed-form frequency equation presented in this article, a study on the changes in the natural frequencies due to the changes in the joint stiffness is performed. An upper limit for the joint stiffness of a SFF is established such that for the joint stiffness above this limit, the natural frequencies of a SFF are very close to those of its flexible-link rigid-joint counterpart. Therefore, the value of this limit can be used to distinguish a SFF from its flexible-link rigid-joint manipulator counterpart. The findings presented in this article enhance the accuracy and time-efficiency of the dynamic modeling of flexible-link flexible-joint manipulators. These findings also improve the performance of model-based controllers, as the more accurate the dynamic model, the better the performance of the model-based controllers.

This study is conducted to provide the reference data for an alarm system to prevent an overturning of a container crane under wind loads. Two methods, namely FSI (fluid–structure interaction) analysis and wind tunnel test, are adopted in this investigation. In order to evaluate the effect of wind load on the stability of the crane, a 50-ton class container crane, widely used in container terminals, is adopted for an analytic model, and 19 values are considered for wind direction as a design parameter. First, the wind tunnel test for the reduced-scale container crane model is performed according to the wind direction using an Eiffel-type atmospheric boundary-layer wind tunnel. Next, FSI analysis for a full-scale container crane is conducted using ANSYS and CFX. Then, the uplift force obtained from FSI analysis is compared with that yielded by the wind tunnel test. Finally, the reference data on the uplift forces for an alarm system are suggested to prevent an accident of a container crane due to windblast.

This study was experimentally carried out to investigate the relationship between fuel-cell performance and the water flooding phenomena at the cathode, which is an important research area of water management in the polymer electrolyte membrane fuel cell. A transparent fuel cell was fabricated to observe the water flooding phenomenon in the cathode channel. Images of the flooding phenomena were obtained by digital and high-speed cameras under various operating conditions involving cell temperature, cathode flowrate, humidifying temperature, cathode backpressure, and oxygen concentration. At the same time, performance was measured at the potentiostatic mode. In this study, investigations for the effects of operating parameters on the water flooding phenomenon, as well as water droplet generation and removal in the cathode flow channel were made. As time elapsed, it was seen that small water droplets formed and then grew into larger water droplets, when the flooding phenomena occurred.

It was also observed that when the cell temperature increased the occurrence of flooding phenomena decreased due to evaporation, and performance was significantly improved. The water droplets in the cathode channel were found to be almost zero at high cathode flowrates, and the instances of the flooding phenomenon were decreased by evaporation as the humidified temperature was increased. On account of increasing cathode backpressure, the flooding phenomenon due to high partial pressure was reduced and as compared to air when oxygen was used as an oxidant, the water distribution was increased. Based on this experimental study, it is seen that the flooding phenomenon is closely related to fuel-cell performance.

In this study, computational fluid dynamics (CFD) analysis is utilized in order to determine the convective heat transfer coefficient of an engine air-cooling system in different air velocity conditions. Various models with different geometric configurations are considered. Based on the CFD results, two formulas are proposed to approximate the values of convective heat transfer coefficients in zero and non-zero air velocities. Finally, two conflicting objective functions including volume of the required material for construction of the finned cylinder and heat release per unit temperature difference are considered. Multi-objective optimization using genetic algorithm is utilized, which generates a multiple set of solutions, each of which is a trade-off between two objectives. The user can select each of the optimal geometric configurations based on the project's requirements. In other words, considering the desired thermal design, designer is able to find the minimum volume of the required material for construction of the finned cylinder, which in turn leads to the least possible capital cost.

The construction and development of different rotor profiles is an important area in connection with the development of screw compressors for specific applications. Geometrical performance figures (using criteria to describe interdependencies of geometrical parameters for screw compressors) for profile optimization are used in order to achieve specific improvements in performance. During this process, rotor profiles and spatial parameters are the main factors. Compared to data derived from the front section of rotor profiles, these figures which also take spatial parameters into account provide a better evaluation of gap conditions and operating efficiency of the compressors under examination.

A ductile failure law and an energy-based failure criterion have been implemented in a 2D finite-element (FE) model to simulate the segmented chip formation process in titanium alloy (Ti–6Al–4V) machining. The variations of stress and strain are taken into account in defining the material failure criterion. The cutting forces and chip morphology calculated by FE model are compared with experimental results in good agreement, validating the FE model. Stresses, strains, cutting temperatures, and stiffness degradation along adiabatic shear bands (ASBs) are analysed during the segment formation process to investigate the segment formation mechanism. It is found that the variation trend of strains is the same as that of temperatures, in addition, the variation of strains and their changing-rate lag slightly behind those of temperatures. These observations provide a new evidence of thermoplastic instability along ASB and increase the understanding of segmented chip formation mechanism. Furthermore, simulation results show that ASB morphology and its forming mechanism are mainly caused by thermoplastic instability in primary deformation zone and friction characteristic in the second deformation zone.

A study of vehicle side mirror power-fold actuator noise characteristic was undertaken, which seeks to correlate subjective evaluation with objective measurements as a basis for development of a product sound quality control algorithm. Psychoacoustic metrics were extracted from the product sound measurements and analysed for manufacturing quality assessment. Two approaches were explored in this study; one is a multiple metric sequential pass-through gate approach and the other is the least square fit regression approach, where measured relevant psychoacoustic metrics are modelled against subjective rating data provided by product sound quality evaluation experts. The ‘gate’ approach using sound pressure level, roughness, and tonality was successfully implemented to segregate bad power-fold actuators from good ones in terms of sound quality. A non-linear, two metric regression algorithm assessing what is a ‘good’ or a ‘bad’ actuator, was then developed and validated through comparison with a linear eight metric regression algorithm. Based on correlation of objective measurement and subjective evaluation results for given product samples, the diagnostic methodology developed in this research is applicable to other products for noise diagnostics and quality control.

Optical fibre probes made by manually operated hot-melt-drawn methods may have unreliable production quality. This can result in unreliable results during use of the probes. This article presents a theoretical model for the construction of optical fibre probes by a hot-melt-drawn method, intending to simulate the optical fibre melt-drawing process using the P-2000 Sutter melt-drawing installation, and investigates changes in length, radius, and geometric profile of the optical fibre. Using preset processing parameters, the study simulates the profile, size, and shape of an optical fibre probe, and the geometric shape and diameter of the probe tip.

Additionally, the article presents an analysis of fabrication parameters to determine which of the three processing parameters, probe diameter, melt-drawing rate, and hard-drawn value, is most significant in determining the length and profile of a simulation model probe.

Electric shovel is one of the most important equipment in surface-mining operations. The medium–tool interaction model is an essential basis in the process of machine design. Therefore, it is important to make the model accurate compared to the actual situation. This article proposes a new medium–tool interaction model based on the analysis of medium–tool interaction mechanism taking into account the actual excavating process. The result of the new model is quite in agreement with the full-scale tests. In order to make the excavating process more efficient, the traditional two-degree-of-freedom (DOF) excavating mechanism is redesigned and a new three-DOF excavating mechanism is obtained. A new electric shovel with three-DOF excavating mechanism is more flexible in that it will perform the excavation process with a favourable excavating angle that can reduce the resistance force involved in medium–tool interaction. Based on the new medium–tool interaction model, the dynamic model of the three-DOF excavating mechanism is established for the mechanics performance analysis. The numeric validation shows that the new excavating mechanism is more efficient in the excavating process.

This work uses a commercial computational fluid dynamics code to predict three-dimensional (3D) vortex flows in a large centrifugal-pump station under construction in China and proposes relevant vortex-eliminating schemes. Because of the complex nature of the vortex flows in sumps, different turbulence models, namely, standard k–ε, re-normalization group k–ε and realizable k–ε models, are first used to investigate their feasibility in predicting flows in a small physical model of an open pump sump, and various vortex streamlines and strength in the sump are predicted, analysed, and compared with the experimental data. The comparisons show that the realizable k–ε model predicts the position and strength of free-surface, sidewall-attached, and floor-attached vortices more accurately than the other two models. Then, the realizable k–ε model is used here to investigate 3D vortex flows in a large pumping-station sump. All the various vortices, such as free-surface, wall-attached vortices, are successfully predicted. Thus, based on the information of location, shape, size, and strength of the calculated vortices, three types of vortex-eliminating devices are proposed and their corresponding vortex suppression effects are analysed. These results will be used as reference for the safe and stable operation of the Hui–Nan–Zhuang pumping station in the future.

Modern aerodynamic optimization design methods for the industrial axial compressor cascade mainly aim at improving both design point and off-design point performance. In this study, a multi-point and multi-objective optimization design method is established for the cascade, particularly aiming at widening the operating range while maintaining good performance at the acceptable expense of computational load. The design objectives are to maximize the static pressure ratio and minimize the total pressure loss coefficient at the design point, and to maximize the operating range for the positive and negative incidences. To alleviate the computational load, a design of experiment (DOE)-based GA–BP-ANN model is constructed to rapidly approximate the cascade aerodynamic performance in the optimization process. The artificial neural network (ANN) is trained by the genetic algorithm (GA) technique and back propagation (BP) algorithm, where the training cascades are sampled by the DOE method and analysed by the computational fluid dynamics method. The multi-objective genetic algorithm is used to search for a series of Pareto-optimum solutions, from which an optimal cascade is found out whose objectives are all better than (ABT) those of the original design. The ABT cascade is characterized by the lower camber and higher turning angle, leading to better aerodynamic performance in a widened operating range. Compared with the original design, the ABT cascade decreases the total pressure loss coefficient by 1.54 per cent, 23.4 per cent, and 7.87 per cent at the incidences of 5°, −9°, and 13°, respectively. The established optimization design method can be extended to the three-dimensional aerodynamic design of axial compressor blade.

Slow-rotating waterwheels are mechanical devices of great historical relevance since they provided power to ancient communities for shifting from a subsistence to a market-oriented economy. Technical studies of these antecessors of hydraulic turbines mainly rely on basic principles that do not take into account the blade-to-blade distance and, therefore, the loss of energy from spillage (parts of the jet flow that do not interact with the moving blades). These effects are included in this article in a novel analytical approximation based on a sequential frame methodology. We apply this extended analytical expression to the analysis of three different sets of parameters referred to a laboratory-scale horizontal waterwheel. Results are compared with those obtained experimentally and, also, with computational fluid dynamics simulations. In contrast to the classical expression that clearly fails to explain the waterwheel behaviour when few blades are employed, our new analytical approximation remarkably agrees with both simulations and experimental data.

A numerical method to analyse the influence of assembly error on spur gear tooth contact load distribution considering bearing elasticity is formulated. In the proposed approach, a set of transformation matrices are used to define the deviation in tooth geometry orientation from the ideal position due to the bearing elasticity and assembly error. To calculate the gear tooth deflection, the theory of contact mechanics is applied to determine the micro deformation field at the surface layer of the contact region, while the finite element model is used to represent the bulk deformation in the rest of the gear structure. An efficient search strategy for obtaining the true contact points of the deformed tooth is employed. In this strategy, the tooth contact load distribution is determined based on the smallest distance between each pair of candidate contact points within a cross-section of the mating teeth, and as well as the corresponding force and moment balance conditions. Finally, the proposed model is applied to analyse the effect of assembly errors defined at eight circumferential positions on the tooth deformation in a geared rotor system comprising of four elastic bearings.

This paper describes the influence of pump operating conditions, such as operating pressures, pump speeds, and oil temperatures, on the friction torque characteristics of internal gear pumps for automobiles. Additionally, it presents a new mathematical model reflecting the influence of the oil temperature on the friction torque. In an internal gear pump, the friction torque was affected by oil temperature as well as operating pressure and pump speed. When the operating pressure was high, the influence of oil temperature on friction torque at a pump speed of less than 1000 r/min was contrary to that at a pump speed of greater than 1000 r/min. It was considered that the friction torque is fundamentally composed of three components: the component dependent on the operating pressure, dependent on the pump speed, and independent of both the operating pressure and the pump speed. However, the component dependent on the operating pressure was affected significantly by not only the pump speed but also the oil temperature. In addition, another factor besides the viscosity of the oil existed in the component dependent on the pump speed. A mathematical model for the friction torque characteristic of the internal gear pump was newly established by adding factors including the oil temperature to the Wilson’s model. The new model was able to represent with accuracy the experimental friction torque characteristic in the internal gear pump under various pump operating conditions.