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Highlights: Analytically modeling the effect of eccentricity on flexible crankshaft and piston secondary motion; Analytically modeling the eccentricity of the crankshaft; Analytically modeling the absolute value of the dynamic displacement of the center of the crankshaft; Showing how sensitive the dynamic displacement in flexible crankshafts is to the changes in its independent variables; Double experimental validation of the analytical models based on the eccentricity of the crankshaft and based on fatigue analysis; A proposed approach of fatigue failure analysis for vehicular dynamic components; A proposed nanostructure of crankshafts for improved structural mechanics. In spite of the fact that the flexibility of the crankshaft of diesel engines exhibits notable nonlinearities, analytical modeling of such nonlinearities is not yet realized. The present study thus analytically models the effect of eccentricity on flexible crankshaft and piston secondary motion. The eccentricity of the crankshaft is modeled as the summation of the hydrodynamic eccentricity and the dynamic mass eccentricity of the crankshaft. The study also models the absolute value of the vibrational dynamic displacement of the center of the crankshaft. The paper proves that such dynamic displacement of the center of the crankshaft is sensitive to the changes in its independent variables. It was found that the most influential parameters on the dynamic displacement of the center of the crankshaft due to vibration are the natural frequency and the eccentricity of the crankshaft. The modeling of the dynamic displacement in a flexible crankshaft was validated using a case study based on the eccentricity of the crankshaft showing a relative error of 4%, which is less than the relative error in the CMEM and GT-Power. Furthermore, the analytical modeling of the dynamic displacement in the flexible crankshaft was validated using another case study based on fatigue analysis of the crankshaft showing a relative error of 9%, which is less than that the relative error in Newman's model of diesel engine fuel consumption and Lansky's model of diesel engine cylinders. The paper also presents a proposed approach of fatigue failure analysis for vehicular dynamic components and presents a proposed nanostructure of crankshafts for improving such fatigue performance. The developed models would help develop efficient diesel engines and help prolong their service life. [ABSTRACT FROM AUTHOR]

Byline: Waleed F. Faris, Zohir BenLahcene, Sany Izan Ihsan This paper deals with dynamics and control policies analysis of semi-active suspension systems for off-road vehicles. Three configurations of these vehicles; two-axle, three-axle and four-axle have been studied and their performances are compared. The application of several control policies of semi-active suspension system, namely skyhook; ground-hook and hybrid controls have been analysed and compared with passive systems. The results show that the hybrid control policy yields better comfort than a passive suspension, without reducing the road-holding quality or increasing the suspension displacement. The hybrid control policy is also shown to be a better compromise between comfort, road-holding and suspension displacement than the skyhook and ground-hook control policies. Skyhook control generally improves sprung mass responses while at the same time increasing unsprung mass responses. On the other hand, ground-hook control generally improves unsprung mass responses at the expense of the sprung mass responses. Results show an improvement in ride comfort and vehicle handling using four-axle over three-axle and two-axle when emphasis is placed on the response of the vehicle body acceleration, suspension and tyre deflection.

Byline: Faried Hasbullah, Waleed F. Faris The application of the linear quadratic regulator (LQR) and fuzzy logic controller (FLC) in the field of active vibration isolation for a vehicle suspension system is presented to overcome the limitation of passive suspension system and the performances of the two active controllers are compared with the passive system. Results show that the performance of the LQR controller is better than the FLC at the expense of control force. The performances of both active controllers are better than the passive system in terms of settling time.

Byline: Waleed F. Faris, Fazidah Saad Generally, the vehicle engine mounting system consists of an engine as the vibration source and several mounts connected to the vehicle structure. The modern engine mounting systems have been successfully used to isolate the driver and passenger from both noise and vibration generated by the engine. However, there is still a need to improve the performance of engine mounting systems because of the requirements of vibration and noise level isolation for passenger cars and also because of the modern car designs that need lighter bodies and more power-intensive engines. Such a weight reduction and increased power requirements will often have adverse effects on vibratory behaviour that it will increase the vibration and noise level. This study is focusing on the current elastomeric engine mounts of different geometry and will also characterise the dynamic properties of elastomeric engine mount. This will be done by having parametric study of different engine mountings. The analysis of engine mounting rubber components should be accompanied by the vibration analysis of the engine mount system. This research opens up a passage to researchers to study and improve the elastomeric engine mount.

Byline: Nabilah Ramli, Hishamuddin Jamaluddin, Shuhaimi B. Mansor, Waleed F. Faris Principal component analysis (PCA) is employed in this study to reduce the size of the neural network input node. Neural network is used to identify the ground vehicle aerodynamic derivatives based on a recorded simple harmonic motion of a ground vehicle model. The study involves the identification using neural network with and without the input optimisation by PCA. Both studies are compared with the identification results from a conventional method, and it is shown that the neural network can approximate functions based on principal components extracted as well as a full-size neural network can.

Byline: Zahir Ahmad Hanouf, Waleed F. Faris The main focus of this paper is the study of the relationship between components of vibration and noise inside the passenger cabin of a production vehicle. The noise inside automobiles is largely composed of contributions from the engine, ground and wind. The engine and tyres successively transfer the vibration via the structural connections to the body panels, which then propagates through the air to the interior of the car cabin. The analysis technique is based on the signal analysis method of sound pressure level and vibration response, and the modal analysis method of vehicle structural components. Firstly, the results were obtained by the noise contour test, which is a contour of sound pressure level, done over the horizontal cross-sectional plane inside the cabin. This was carried out under the random excitation, to predict the dominating noise frequencies. Secondly, the vibration response on the front suspension in the vertical direction under the engine excitation was studied. Finally, the modal analysis was used to determine the dynamic characteristics of every component of the vehicle body panels; this would contribute to the interior noise. It was found that the interior noise of the car vehicle is mainly caused by the excessive bending mode vibration of the front suspension and twisting mode vibration of the cross-roof beam.

Byline: Waleed F. Faris, Zohir BenLahcene, Sany Izan Ihsan Handling and ride quality are affected by many factors, including high-frequency vibrations, body booming, body roll and pitch motion, vertical motion by the suspension system and frequency vibration transmitted from the road input excitations. This article focuses on the most significant vibration source that affects handling and ride quality, which is the suspension system. Passive suspension has been taken as the starting point of this work, in which we discuss the model in context. Semi-active suspension systems are introduced with the aim of exploring the performance of the system compared with passive suspension. Several control policies of semi-active systems, namely, skyhook, ground-hook and hybrid controls, are presented. Their ride comfort, suspension displacement and roadholding performances are analysed and compared with passive systems. The analysis covers both transient and steady-state responses in the time domain and transmissibility response in the frequency domain. The results show that the hybrid control policy yields better comfort than a passive suspension, without reducing the road-holding quality or increasing the suspension displacement for a typical off-road vehicle. The hybrid control policy is also shown to provide a better compromise between comfort, road-holding and suspension displacement than the skyhook and ground-hook control policies.

Byline: Waleed F. Faris, Sany Izan Ihsan, Mehdi Ahmadian Vehicle models used to evaluate performance and dynamic behaviour are either discrete models, which includes quarter, half, and full car models, or continuous models using finite element modelling. In this work our focus will be on discrete models, which have more popularity with ground vehicle analysts owing to their shorter computational time and lower cost compared with continuous models. In this paper, ride comfort, suspension displacement and road-holding performances are compared for three different models – quarter (Q), half (H) and full (F) car models. In each model, semi-active system controls, namely skyhook, groundhook and hybrid controls, are used along with the conventional passive system. The analysis covers both transient and steady-state responses in the time domain and transmissibility response in the frequency domain. Results show that while the responses give generally the same trend, the simpler model gives significantly higher responses.

Byline: Waleed F. Faris, Sany Izan Ihsan, Mehdi Ahmadian Several control policies of semi-active system, namely skyhook, groundhook and hybrid controls are presented using a half-car model, as a continuation of the previous work on quarter-car model. Their ride comfort, suspension displacement and road-holding performances are analysed and compared with passive system. The analysis covers both transient and steady state responses in time domain and transfer function in frequency domain. The results show that the hybrid control policy yields better comfort than a passive suspension, without reducing the road-holding quality or increasing the suspension displacement for typical passenger cars. The hybrid control policy is also shown to be a better compromise between comfort, road-holding and suspension displacement than the skyhook and groundhook control policies.

Byline: Fadly Jashi Darsivan, Waleed F. Faris, Wahyudi Martono The application of the Extended Minimal Resource Allocation Network (EMRAN) in the field of active vibration isolation for an automotive engine system is presented. As the source of disturbance the engine is mounted on a two passive mounts in parallel with an active force actuator. EMRAN is implemented to control the force actuator and to isolate this disturbance. The characteristic of EMRAN and the criteria for growing and pruning of hidden layers are presented. EMRAN's capability is compared with a PID controller and NARMA-L2 neural controller and shows superior performance in rejecting sinusoidal disturbances and achieving the chassis's vibration isolation.

Byline: S.I. Ihsan, Waleed F. Faris, M. Ahmadian Several control policies of semi-active systems, namely skyhook, groundhook and hybrid controls, are presented. Their ride comfort, suspension displacement and road-holding performances are analysed and compared with passive systems. The analysis covers both transient and steady-state responses in the time domain and transmissibility response in the frequency domain. The results show that the hybrid control policy yields better comfort than a passive suspension, without reducing the road-holding quality or increasing the suspension displacement for typical passenger cars. The hybrid control policy is also shown to be a better compromise between comfort, roadholding and suspension displacement than the skyhook and groundhook control policies.

The supercharging centrifugal compressor with a vaneless diffuser is a key element in diesel powertrains that has not been comprehensively modelled using explainable mathematical trends. This study thus develops an analytical model for this type of compressors for hybrid H 2 -Biodiesel dual-fuel engines with cooled EGR. Specifically, for this proposed type of compression ignition system, the study develops an analytical model of the velocities at the exit of impeller of the supercharging compressor. In addition, a sensitivity analysis is conducted on the developed models of the total power required to drive the compressor and its mechanical efficiency. The developed models have been validated using case studies that are based on field data gathered experimentally. Furthermore, a modified model of the Stanitz's slip factor is presented for radial blades accounting for the Coriolis circulation, boundary layer effect, and blade thickness. The modified Stanitz's slip factor provides better accuracy of matching the experimental results with relative error of 1%. The relative error with respect to the parameters of the velocities at the impeller and the analytical model of the power required to drive the rotor of the compressor is 7%. In addition, the relative error with respect to the model of the mechanical efficiency of the compressor is 10%. These relative errors are of an order of magnitude of deviation that is comparable with that of widely recognized models in the field of vehicle powertrain modelling such as the CMEM and GT-Power. These developed models follow from the principles of physics so that they are widely valid models. Having addressed and corrected flaws in corresponding models presented in key references in this research area, these developed models can help more effectively evaluate the power input to this type of compressors and thus the fuel consumption reducing the environmental foot-print thereof. [ABSTRACT FROM AUTHOR]

Active disturbance rejection control (ADRC) for a quarter-car active suspension system is proposed. The performance of ADRC is compared with benchmark (LQR control) from current literature. A simulation experiment is performed to investigate the performance of ADRC in comparison with passive system and the LQR control, as well as to test the ability of ADRC to cope with varying process. Results show that ADRC performs better than the benchmark control and is able to cope with varying process commonly seen in active suspension system. [ABSTRACT FROM AUTHOR]

Three-phase induction motors have been used in a wide range of industry applications. Using modern technology, the speed of induction motor can be easily controlled by variable frequency drives (VFDs). These drives use high speed power transistors with various switching techniques, mainly PWM schemes. For several decades, conventional control systems were applied to electric drives to control the speed of induction motor. Although conventional controllers showed good results, but they still need tuning to obtain optimum results. The recent proposed control systems use fuzzy logic controller (FLC) to enhance the performance of induction motor drives. In this paper, a fuzzy logic based speed control system is presented. The proposed controller has been designed with MATLAB/SIMULINK software, and it was tested for various operating conditions including load disturbance and sudden change of reference speed. The results showed better performance of the proposed controller compared with the conventional PI controller. [ABSTRACT FROM AUTHOR]

The article examines an axisymmetric vibration of an isotropic circular plate with a piezoceramic annular plate attached. It presents a free vibration analysis of the plates as well as the implementation of a parametric study to provide some insight into plate geometric influence on fundamental frequency. The use of finite difference method is discussed.

The article focuses on the aspects of research in ride quality or ride comfort of passenger cars, which is regarding the response of a vehicle to road conditions other than to its occupants. It explores how the response of a vehicle affects its occupants. It examines significant literature related to the topic and discusses the different approachesm such as theoretical or experimental, used in research to evaluate ride quality.

The article presents a study on the effect of C++ program in determining the ratio of inertia and damping coefficients of the squeeze film dampers (SFDs) with central groove at different excitation frequencies. It mentions that the C++ computer program can compute the stiffness value of damping coefficients. Result shows that highest damping coefficient ratio from excitation frequencies were beyond 2,500 hertz (Hz), while the inertia ratio was constantly increasing and decreasing.

The article presents a study on the optimal brake pad design for squeal noise reduction through a response surface methodology (RSM). It states that the RSM is incorporated with complex eigenvalue analysis to examine the most design factors which significantly affect squeal brake noise reduction. The study revealed that the rise Young's modulus of brake pad along with increasing chamfer and the reduce of distance between two slots reduces the squeal noise.

The article presents a study which determines the sound or noise transmission through a cylindrical structure aircraft fuselage and to identify the influence of mode shapes on noise reduction. The study uses numerical method through structural and acoustical modes to validate noise reduction. The study also uses a criterion for choosing eigen modes for the modal truncation which have an influence on noise reduction.

The work aims to study the root mean square (RMS) responses to acceleration input for four state variables: the mS vertical acceleration, the mS pitch angular acceleration and the front and rear deflections of the suspensions. A half-car two degree-of-freedom model of semi-active control scheme is analyzed and compared with the conventional passive suspension system. Frequency response of the transfer function for the heave, pitch of the sprung mass and suspension deflections are initially compared and then mean square analysis is utilized to see the effect of semi-active scheme. Results indicate that significant improvements were achieved in the sprung mass heave and pitch responses using semi-active control scheme. However results for the rear and front suspension deflection show that there are limiting values of damping coefficient beyond which, the semi-active scheme becomes disadvantageous than the passive system. [ABSTRACT FROM AUTHOR]

This paper proposes the application of neural network as a controller to isolate engine vibration in an active engine mounting system. It has been shown that the NARMA-L2 neurocontroller has the ability to reject disturbances from a plant. The disturbance is assumed to be both impulse and sinusoidal disturbances that are induced by the engine. The performance of the neural network controller is compared with conventional PD and PID controllers tuned using Ziegler-Nichols. From the result simulated the neural network controller has shown better ability to isolate the engine vibration than the conventional controllers. [ABSTRACT FROM AUTHOR]

The paper presents a systematic procedure and details of the use of experimental and analytical modal analysis technique for structural dynamic evaluation processes of a vertical machining centre. The main results deal with assessment of the mode shape of the different components of the vertical machining centre. The simplified experimental modal analysis of different components of milling machine was carried out. This model of the differentmachine tool's structure is made by design software and analyzed by finite element simulation using ABAQUS software to extract the different theoretical mode shape of the components. The model is evaluated and corrected with experimental results by modal testing of themachine components in which the natural frequencies and the shape of vibration modes are analyzed. The analysis resulted in determination of the direction of the maximal compliance of a particular machine component. [ABSTRACT FROM AUTHOR]

This work is devoted to the fabrication and investigation of the Squeeze Film Dampers (SFDs) which are widely used in many applications. This include the fabrication of a test rig and several dampers with different sizes and two different materials which composite and non-composite. Composite dampers (Glass/epoxy), each consists of 30 layers, were fabricated by hand lay-up method. Outer and inner diameters of all the fabricated dampers were maintained as 60 and 40 mm respectively. Non-composite dampers (Steel) were fabricated and tested using turning machine. Three dampers of different lengths were examined for both materials. A rotor-bearing system for the analysis has been designed and fabricated. The test rig consists of mild steel shaft, two supports, oil pressure system, and two self-alignment ball bearings were fixed on each end support. Two squeeze film dampers were used for the two support ends. Vibration amplitude has been examined for all the fabricated dampers at different shaft rotational speeds. The first resonance speed was examined for all the dampers tested. Results show that the vibration amplitude of the steel damper was lower than Glass/epoxy dampers with the same L/D ratio. On the other hand, a considerable weight saving has been achieved by using Glass/epoxy composite dampers. It has been found that the performance of squeeze film damper improved with increasing length/diameter ratio (L/D) within the range tested. [ABSTRACT FROM AUTHOR]

We present a numerical procedure to solve the axisymmetric vibration problem of statically loaded annular plates. We use the von Kármán nonlinear plate model to account for large deformations and study the effect of static deflections on the natural frequencies and mode shapes for six combinations of boundary conditions. The shooting method is used to solve the resulting eigenvalue problem. Our results show that static deformations have a significant effect on the natural frequencies and small effect on the mode shapes of the plate. Further, the results show that the presence of in-plane stresses has a significant effect on the natural frequencies. [ABSTRACT FROM AUTHOR]

The flexibility of a crankshaft exhibits significant nonlinearities in the analysis of diesel engines performance, particularly at rotational speeds of around 2000 rpm. Given the explainable mathematical trends of the analytical model and the lack of available analytical modeling of the diesel engines intake manifold with a flexible crankshaft, the present study develops and validates such a model. In the present paper, the mass flow rate of air that goes from intake manifold into all the cylinders of the engine with a flexible crankshaft has been analytically modeled. The analytical models of the mass flow rate of air and gas speed dynamics have been validated using case studies and the ORNL and EPA Freeway standard drive cycles showing a relative error of 7.5% and 11%, respectively. Such values of relative error are on average less than those of widely recognized models in this field, such as the GT-Power and the CMEM, respectively. A simplified version for control applications of the developed models has been developed based on a sensitivity analysis. It has been found that the flexibility of a crankshaft decreases the mass flow rate of air that goes into cylinders, resulting in an unfavorable higher rate of exhaust emissions like CO. It has also been found that the pressure of the gas inside the cylinder during the intake stroke has four elements: a driving element (intake manifold pressure) and draining elements (vacuum pressure and flow losses and inertial effect of rotating mass). The element of the least effect amongst these four elements is the vacuum pressure that results from the piston's inertia and acceleration. The element of the largest effect is the pressure drop that takes place in the cylinder because of the air/gas flow losses. These developed models are explainable and widely valid so that they can help in better analyzing the performance of diesel engines. [ABSTRACT FROM AUTHOR]

An abstract of the article "Investigation into noise problems in vehicle structure using vibro-acoustic approach," by Zahir Ahmad Hanouf and Waleed F. Faris is presented.