Raja Ishak Raja Hamzah

Vibration analysis of supported thick-walled cylindrical shell made of functionally graded material under pressure loading

This paper presents a study on the vibration of a supported thick-walled cylindrical shell made of functionally graded material (FGM) subjected to pressure loading. The FGM shell is developed in accordance to the volume fraction law from two constituents, namely stainless steel and nickel. For the power law exponent distribution the top surface of the structure is steel/nickel-rich, whereas the bottom surface is nickel/steel-rich. The FGM properties are graded along the thickness direction of the shell. The supported FGM thick shell equations with one ring and pressure loading are established based on first-order shear deformation theory. The governing equations of motion were employed, using energy function and by applying the Ritz method. The boundary conditions represented by the end conditions of the FGM thick shell are simply supported–simply supported, clamped–clamped, free–free, clamped–free, clamped–simply supported, free–simply supported, sliding–free and sliding–clamped. The effects of the volume fraction law exponent, pressure loading, ring position and different boundary conditions on natural frequency characteristics are studied. The results obtained are compared with those available in the literature.

Artificial neural network model for monitoring oil film regime in spur gear based on acoustic emission data

The thickness of an oil film lubricant can contribute to less gear tooth wear and surface failure. The purpose of this research is to use artificial neural network (ANN) computational modelling to correlate spur gear data from acoustic emissions, lubricant temperature, and specific film thickness (λ). The approach is using an algorithm to monitor the oil film thickness and to detect which lubrication regime the gearbox is running either hydrodynamic, elastohydrodynamic, or boundary. This monitoring can aid identification of fault development. Feed-forward and recurrent Elman neural network algorithms were used to develop ANN models, which are subjected to training, testing, and validation process. The Levenberg-Marquardt back-propagation algorithm was applied to reduce errors. Log-sigmoid and Purelin were identified as suitable transfer functions for hidden and output nodes. The methods used in this paper shows accurate predictions from ANN and the feed-forward network performance is superior to the Elman neural network.

Frequency analysis of multiple layered cylindrical shells under lateral pressure with asymmetric boundary conditions

Natural frequency characteristics of a thin-walled multiple layered cylindrical shell under lateral pressure are studied. The multiple layered cylindrical shell configuration is formed by three layers of isotropic material where the inner and outer layers are stainless steel and the middle layer is aluminum. The multiple layered shell equations with lateral pressure are established based on Love’s shell theory. The governing equations of motion with lateral pressure are employed by using energy functional and applying the Ritz method. The boundary conditions represented by end conditions of the multiple layered cylindrical shell are simply supported-clamped(SS-C), free-clamped(F-C) and simply supported-free(SS-F). The influence of different lateral pressures, different thickness to radius ratios, different length to radius ratios and effect of the asymmetric boundary conditions on natural frequency characteristics are studied. It is shown that the lateral pressure has effect on the natural frequency of multiple layered cylindrical shell and causes the natural frequency to increase. The natural frequency of the developed multilayered cylindrical shell is validated by comparing with those in the literature. The proposed research provides an effective approach for vibration analysis shell structures subjected to lateral pressure with an energy method.

A Review of Acoustic Emission Technique for Machinery Condition Monitoring: Defects Detection & Diagnostic

Acoustic emission (AE) measurements are one of many non-destructive testing methods which had found applications in defects detection in machines. This paper reviews the state of the art in AE based condition monitoring with particular emphasis on rotating and reciprocating machinery applications. Advantages and limitations of the AE technique in comparison to other condition monitoring techniques in detecting common machinery faults are also discussed.

Effects of Ring Support and Internal Pressure on the Vibration Behavior of Multiple Layered Cylindrical Shells

This paper presents the study on natural frequency characteristics of a multiple layered cylindrical shell with ring support under internal pressure. The multiple layered cylindrical shell configuration is formed by three layers of isotropic materials where the inner and outer layers are stainless steel and the middle layer is aluminum. The isotropic multiple layered shell equations with ring support and internal pressure are established based on first order shear deformation theory (FSDT). The governing equations of motion were employed by using energy functional and by applying the Ritz method. The boundary conditions represented by end conditions of the multiple cylindrical shell are simply supported-simply supported (SS-SS), clamped-clamped (C-C), free-free (F-F), clamped-free (C-F), clamped-simply supported (C-SS), and free-simply supported (F-SS). The influences of internal pressure and ring support and the effect of the different boundary conditions on natural frequencies characteristics are studied. The results are validated by comparing them with those in the literature.

Development of Audible Signal Control System for Electric Vehicle as Pedestrian Detection

This paper describes and discusses the development of the control system to produce engine sound as audible information for pedestrian to detect the Electric Vehicle (EV) presence instead of alarm type noise. EV produces less noise when travels at low speed condition and can bring unexpected accident to the road user. Various alarms were introduced by the car manufacturers to prevent this problem but the implementation of this system has brought some inconveniences to the EV user since EV is known for its calm and quiet. The engine sound that will be the output of the control system must meet the International Standard Organization (ISO) standard as minimum noise emitted from the vehicle and also as cue sound for pedestrian detection. The introduction of engine sound in EV at the low speed manoeuver is expected to resolve the safety issues among pedestrian and at the same time maintain the EV quality to its user.

Adjustable Acoustical Performance Based on Deformable Origamic Shapes: A Preliminary Experimental Investigation

This paper describes a preliminary investigation on the possible use of deformable origamic shapes as a technique to provide adjustable acoustical performance in multi-purpose hall. The term ‘deformable’ means that the origamic shape undergoes deformation which automatically resulted into the change of its geometrical configurations. The experimental investigation has been carried out on three types of origamic shapes with several geometrical configurations. The measurement tests were conducted in a reverberation room and in accordance to ISO 354:2003 Measurement of Sound Absorption Coefficients in a Reverberation Room. Findings from the preliminary investigation show good trends indicating that the origamic shapes have the capability of adjusting the sound absorption coefficients by varying their geometrical configurations. Following those results, future works with details investigation will be undertaken as to validate the preliminary results.

Measurement of Noise inside the Compartment and Vibration on both Sides of Elastomeric Powertrain Mounts of Passenger Car

This paper presents an evaluation on elastomeric mount used to isolate vibration from powertrain to chassis or structure vehicle. The assessments started with measurement of noise inside compartment, and exhaust noise. This is followed by the measurement of vibration on both sides of elastomeric mounts. The noise in the compartment and exhaust noise is measured according to BS 6086: 1981 and BS ISO 5130: 2007. The noise in the compartment and vibration is tested in three conditions. Firstly, engine is run-up with load (driving at second gear); secondly, without load; and thirdly, without load but hanging. A microphone is fixed at the ear of the mannequin. The fast response and A weighting sound level meter were used for measurement noise in the compartment and exhaust noise. The vibration is measured in terms of acceleration on both sides of each elastomeric powertrain mounts. Two accelerometer transducers are fixed on both sides of powertrain elastomeric mounts. One side was identified as a source of vibration and the other as receiver of vibrations. The results showed that the pattern of overall vibration level on source and receiver increased from 1050 RPM (idling) to 4000 RPM on all test conditions. Vibration transmitted to chassis or receiver structure was analyzed using transmissibility concept. By evaluating test condition of engine run-up without load, informed that the front and rear mounts showed a high level transmissibility contributing to structure-borne noise.

Measurement of Vibration Power Flow through Elastomeric Powertrain Mounts in Passenger Car

The effectiveness of vibration isolator or mount can be done by quantifying the vibration energy flow through the isolators. This can provide information on the quantification of the vibration energy flow from the powertrain to the structure or chassis. Vibration energy flow through mount is identified as vibration power flow that is one of vibration transmission paths. This paper presents vibration power flow through four elastomeric mount. The vibration (source and receiver of accelerations) was measured by running engine at constant speed and without load conditions in varying speeds starting from 1050 RPM to 4000 RPM. The vibration was measured only in z-direction (vertical direction). The noise inside compartment was measured at the condition of engine run-up without load condition and was measured starting from 1050 RPM to 4000 RPM engine speed. The results from vibration power flow analysis showed that the main vibration energy transmission was high from front mount and rear mount, around engine speed 3200 RPM, and booming noise occurred around 3200 RPM due to structure-borne noise.