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In building many complex engineering structures, there are many types of joining methods such as welding and fasteners that can be implemented. Modeling for joints in finite elements can be challenging as it sometimes has limiting factors that cause the prediction of the dynamic behaviour of the actual joints to be less accurate. This study aims to demonstrated several approaches of finite element modeling for spot-welded joints ad to analyse its accuracy through the correlation of modal data from experimental modal analysis. These modeling approaches are created by creating and manipulating the elements at the associated location of the spot weld joint on a top-hat beam structure. Four different approaches of spot weld modeling that uses the modeling strategies performed in other studies were created. The spot weld models are validated by comparing the modal properties of the tested structure which are obtained through finite element analysis and experiments. Model updating was performed on all models in order to observe the ability of model improvement in those different modelling approaches. The findings show that the model that uses solid elements has the lowest error compared to the model that uses beam elements. The model that uses multiple-beam elements shows the ability to be improved the most. The model that uses the simplest modeling approach using a single beam has the highest error and shows the lowest improvement after model updating. It was found that solid element is more suitable to model spot weld and the application of solid element for spot weld joints should be investigated in more types of analyses.

The combination of materials between metal alloys and composite materials known as fibre metal laminates (FMLs) has been used for thousands of years to reach better performance requirement. The aluminium alloys (Al 2024-T0) and three different composite materials with two different stacking sequences by hand layup method and tested for evaluating the mechanical properties with considerable trials. The vibration characteristic of FMLs plate were experimentally studied by impulse excitation techniques under fixed-free and fixed–fixed boundary conditions. The accuracy of the results was verified by comparing the ABAQUS finite element method. The results indicated with the presence of aluminium alloy plates in the composite layers, the natural frequency will increase as the value of stiffness increase. The boundary conditions significantly affected the natural frequency of FML plates because of the restraint effect at the edges.

In the automotive structure, there are different components that utilise aluminium alloy (AA) sheets and it is used widely in the car body-in-white which comprise bumpers and the crash box structure at the front end of the car which specifically designed to withstand the event of collision. As the structures are also experiencing dynamic loading, it were also a concern for the structures to show satisfied modal properties. In this study, the modal properties of the crash box structures are investigated along with the effect of the modal properties towards the crashworthiness behaviour of the structure itself with the approach of finite element analysis. Experimental modal analysis was also done to further validating the finite element analysis of the modal properties. Three different designs of trigger mechanisms are applied towards the crash box structure to observe on both findings. For the connector element, equivalent nodes of both parts of the crash box structures are used. For the results, the correlation from both findings did show that the presence of trigger mechanism did decreased the magnitude of natural frequencies as well as the mode shape as shown by crash box type 3 by 9.50% and for the crashworthiness output, the crashworthiness behaviour of the crash box with trigger mechanisms were better in term of the collisions phases indicated by the primary peak force and the secondary peak force from the force-displacement curve as also shown by crash box structure type 3 with the percentage of 22.59%. The study does shows that the stiffness and mass distribution due to the presence of trigger mechanism do affect the modal properties of a structure as well as its crashworthiness output.

The utilisation of biodiesel nowadays has become familiar with rapid production types of biodiesel in order to replace the dependency on the fossil fuel parallel to the implementation of green technology that emphasises the products to be more environmental-friendly. Nevertheless, the emerges of various kinds of biodiesel cannot be simply used, despite using the biodiesel does not need any major modification on the engine; it still needs a few analyses that must be done to determine whether it will give advantages or disadvantages. Therefore, this research was carried out to investigate the effect of using palm oil methyl ester (POME) biodiesel on the engine in terms of noise emission. The sound intensity mapping method was used to indicate the effectiveness of the biodiesel by identifying the noise radiation. Along with the mapping, the sound power level (SPL) is also being obtained to provide a clear comparison between the parameters. Generally, switching up the engine speed and load increased the sound power level. Based on the results obtained related to the SPL, the intensity mapping tends to show a higher colour-coded in the noise source image for the higher engine speed and load setup. It was found that the engine speed and load give a significant contribution to noise emission produced by the engine, and it can be inferred that this method can be utilised to accomplish the noise emission analysis.

Model updating methods can be adopted to improve the correlation level between the finite element model of a spot welded structure and its test model. However, in the presence of contact interfaces in the vicinity of the welded areas, improving the correlation level is problematic and challenging. An approach for correlating the finite element model of a welded structure with contact interfaces using finite element model updating and modal testing is proposed. The proposed approach was tested on a car front-end module structure that consisted of nine components and 76 resistance spot-welded joints used to assemble the components. CWELD and CELAS1 element connectors were used to represent the spot-welded joints and contact interfaces in the finite element modelling and updating. This approach was applied successfully to predict the modal parameters of the car spot-welded front-end module. The total error of the initial finite element model of the structure was reduced from 27.13% to 5.75%. The findings of this work suggest that the proposed approach has a great potential for use in investigating the dynamic behaviour of various spot-welded structures without a significant decline in accuracy.

Nowadays, computational modelling and simulation are highly popular to increase the efficiency, productivity and shorten the product development period. The quality of a structure also can be determined by using computational analysis such as finite element analysis. Body-in-white structure, as one of the most important structures in the automotive field, has gained a lot of interest as the topic of research. This increase the demand of having a good finite element model of the structure. However, since body-in-white is a highly complicated structure, sometimes modelling simplification cannot be avoided. This study intended to investigate the level of accuracy of the simplified body-in-white model that was modelled by using several modelling strategies. The first body-in-white finite element model was modelled by neglecting the existing joint element in its actual structure. The other body-in-white model includes the joint element by including two different one-dimensional elements to replicate the joining in BIW actual structure. Validation on these body-in-white models are performed by correlating the finite element modal properties with the experimental modal properties. The discrepancies that had surfaced after the correlation was reduced by using a model updating method. The discussed results showed that as the model is under major simplification, several parameters were inaccurately assumed in the initial body-in-white model. Thus, the model updating method has successfully determined the less accurate parameter and the level of discrepancies between the model and experimental data were successfully reduced.

Nanofluids are used in heat exchanger system as efficient heat transfer fluids to improve heat transfer performance by passive method. Besides, another special active technique by implementing the low or high frequency vibration, which was used in heat exchanger to enhance the heat transfer performance. This paper reviews the heat transfer augmentation in heat exchanger by using nanofluids, vibration excitation of low and high frequency vibration. The use of nanofluids in heat exchanger system can provide better effective thermal conductivity compared to the conventional coolants. The presence of nanosize particles in nanofluids performed better mixing flow with higher thermal properties compared to pure fluids. Additionally, the active method by inducing low and high frequency vibration technology was applied in heat exchanger system. The heat transfer augmentation by vibration excitation was resulted from the mitigation of the fouling resistance on the surface of the tube wall. It was found that vibration excitation not only increase the heat transfer rate, but also might be a solution for fouling reduction. Hence, there is a great potential of using nanofluids together with vibration excitation simultaneously in heat exchanger system to improve the heat transfer performance.

Fiber metal laminates (FMLs) offer significant improvement over current available materials for structure materials due the excellent mechanical properties. In this work, the dynamical mechanical properties of the carbon fiber/epoxy, glass fiber/epoxy, aluminium 2024-T0, and fiber metal laminates was carried out. The composite materials have been manufactured by hot press machine. Non-destructive testing techniques are being used in the characterization of composite materials. In this work, free vibration analyses by striking an impact hammer at the free end were conducted to determine the dynamic characteristics of the samples. The results show that combination glass fiber/epoxy with aluminium 2024-T0 offer greater natural frequency value compare to carbon fiber/epoxy with aluminium 2024-T0. The laminate thickness of play a dominant role in differences of natural frequency values.

Southeast Asian countries stand at a crossroads concerning their shared energy future and heavily rely on fossil fuels for transport and electricity. Within Asia, especially India and China lead the world renewable energy generation undergoing a period of energy transition and economic transformation. Southeast Asian countries have huge potentials for sustainable energy sources. However they are yet to perform globally in renewable energy deployment due to various challenges. The primary objective of the study is to examine the renewable energy growth and analyse the government policies to scale up the deployment of renewables for power generation substantially. The study also offers policy recommendations to accelerate renewable energy exploitation sustainably across the region. To achieve the ambitious target of 23% renewables in the primary energy mix by 2025, ASEAN Governments should take proactive measures like removal of subsidies of fossil fuels, regional market integration and rapid implementation of the existing project. Eventually, each of this strategy will necessitate sustained leadership, political determination, and concrete actions from stakeholders, in particular, increased cooperation across the region.

Vibrations are well known as the source of problem in the damage and loss of control of equipment which can reduce the efficiency of a machine. Few methods can be done to control the vibration and one of it is by adding absorbers. In this study, the concept of attached multiple vibration absorbers to a simply-supported beam was applied to reduce the structural vibration amplitude. The method employed in this research was finite element simulation of ANSYS® APDL. The frequency range of the study was set between 5 to 1000 Hz in which capture up to four modes shapes of the beam. Further study was conducted by positioning the absorber at three different locations which resulted the vibration reduction of 33% when positioning at middle of the beam. The experiment was continued in depth by adding multiple vibration absorbers from two to ten absorbers. The overall vibration reduction achieved for multiple absorbers was 89% (with attached four and eight absorbers) compared to a single absorber which only achieved 33% reduction. t can be concluded that adding multiple absorbers produce better vibration reduction compared to single absorber. However, adding more vibration absorbers need to be considered thoroughly since excessive weight will result in less fuel efficiency towards vehicles, aerospace, automotive and machine systems.

Model updating is concerned about the correction of finite element models by processing the record of dynamic response from test structures in order to have an accurate model for any simulated analysis. Finite element model updating had emerged years ago as an important subject in structural dynamics. It has been used frequently and has been successfully applied to many fields especially in detecting the dynamic stiffness of a structure. The purpose of this study is to perform model updating of a go-kart chassis structure in order to reduce the percentage of error between the experimental modal analysis (EMA) and finite element analysis (FEA). Modal properties (natural frequency, mode shapes, and damping ratio) of the go-kart chassis structure were determined using both EMA and FEA. Correlation of the modal parameters gathered in FEA and EMA was carried out before optimizing the data from finite element. By adjusting the selective parameters, incongruities between those two analyses are generally reduced. The sensitivity of selected parameters is also obtained. The significant reduction in percentageof error before and after model updating procedure was carried out in this study clearly shows that model updating technique is a reliable method in reducing the discrepancies between EMA and FEA. Therefore, in cases of high discrepancies between analytical and actual test data, model updating can be considered as an option in order to obtain better correlation between those two sets of data.

Laser stitch welding is one of the most reliable and efficient permanent metal joining processes in the automotive industry, particularly in the manufacturing of a car body-in-white (BIW). It is widely known that this welding process induces the generation of residual stresses that can influence the dynamic behaviours of welded structures. In order to accurately predict the dynamic behaviours of these welded structures, it is important to experimentally understand the influence of residual stress. Therefore, this study addresses the finite element modelling method of thin steel welded structures with and without the influences of residual stress in order to identify its effect towards dynamic behaviours. The finite element models of thin steel welded structures are developed by employing the area contact model (ACM2) format element connector. The accuracy of the finite element models is then compared in terms of natural frequencies and mode shapes with the experimental counterparts. The dynamic behaviours of the measured structure are obtained using an impact hammer with free-free boundary conditions. The results demonstrate the importance of considering the influence of laser stitch welding residual stress in predicting the dynamic behaviours of thin steel welded structure.

Modal analysis is an approach to determine the dynamic behavior of a structure through numerical analysis or experimental approach. Nowadays, numerical analysis has been preferred by most researchers and engineers compared to experimental analysis to analyze the structure due to expenditure and time consuming factors of the research. Recently, numerical analysis is done computationally or well known as Finite Element Analysis (FEA) by using finite element (FE) model to replicate the real test structure. Instead of advantage of FE analysis, the trustworthiness of FE model has been questioned since simplification has been made during design stage for complex structure and inaccurate of geometry input of the model. Hence, this paper is carried out to reduce the discrepancies between numerical prediction results with measured test data on FE model of exhaust structure by implementing FE model updating using SOL200 algorithm. Initially, the FE model is running on normal mode analysis SOL103 to extract the modal parameters such as natural frequency and mode shape. Then, the numerical pre-diction result has been correlated and validated with measured test data obtained through Experimental Modal Analysis (EMA). Due to disagreement between numerical result and experimental data in correlation process, the FE model has been updated using SOL200 algorithm. The percentage error between numerical prediction result and measured test data is minimized from 5.67 to 3.23% after been updated. It’s shown the capability SOL200 algorithm in preparing the reliable FE model before been used for further analysis such as structural dynamic modification.

Thermal systems more efficient by emanating from industrial applications and space program galvanized interest in ways by increasing heat transfer is the system. The main aim of this paper is to investigate experimentally the effects of the vertical vibration and force convection on the average Nusselt number in a longitudinal finned tube. The finned tube was located inclined or horizontally in different angles of 0°, 30° and 45°. The effect of the excitation frequency covers below 16 Hz with various heat fluxes ranged from 500-1500 W/m2. It was noticed that the good agreement between the experimental measurement and the previous experimental studies with deviation of 5%. The results showed that average Nusselt number values at angle 45° from longitudinal finned tube were higher by up to 14%, 16% compared with the angles 30°, and 0°, respectively. Furthermore, it can be summarized that the vertical vibration significantly affects to the average Nusselt number from longitudinal finned tube cylinder and the influence on the heat transfer coefficient for this system should be considered.

It is important to understand the natural frequencies and the mode shapes for automotive structure such as crash box as it will be subjected to the dynamic loading in its real application. In addition, it is also important to study other dynamic behaviour such as crash and buckling as crash box is one of energy absorbing member that is intended for car safety during collision. In this study, modal properties of three different crash box models joint by three different joint modelling strategies and also their crash and buckling behaviour was analysed and investigated. Computational frequency analysis, dynamic crash analysis and nonlinear buckling analysis was performed on all of crash box models. the crash box modelled with node equivalent method to represent the welded joint shows higher stiffness at the joining area and therefore shows higher value of natural frequencies that the model with CBEAM and CBAR elements as their joining elements. In term of crash behaviour, the model with CBEAM element shows higher reaction force compared to the CBEAM. This proves that different type of joint modelling strategies behaves differently.

The dynamic behaviour prediction scheme of carbon fibre composite structures are extremely challenging to be performed due to the geometrical ply-by-ply properties and the ply orientation issues. In this paper, a laminated carbon fibre reinforced epoxy plate with elastic and linear layers was used with aim to investigate the dynamic behaviour of the carbon fibre reinforced epoxy using practical modelling scheme via finite element modelling and updating method. A simplified FE model of the CFRE plate was developed using shell element properties known as PSHELL to represent geometrical laminated properties. Subsequently, the dynamic behaviour of the FE model was calculated using Nastran SOL103. Potential updating parameters of the FE model was analysed and identified using the sensitivity analysis. The model updating method was then used to update the initial FE model of the CFRE plate based on the experimental modal analysis (EMA) result. The comparison of the results were used in verifying the accuracy of the updated FE model of the CFRE plate. The result suggested that the PSHELL properties can be used efficiently to represent the geometrical laminated properties of the CFRE plate without considering the geometrical effect of ply-by-ply properties.

Structural dynamic modification (SDM) techniques are important in structural optimisation of the system to modify the dynamics behaviour of the structure. It can be implemented by utilising the dynamic test data to alters the dynamic behaviour of the structure. However, there are some concern in the design process in which the undesirable mode shapes movement of structure are occurred along side with desired natural frequencies. Therefore, the SDM technique can be used as to varying the predicted dynamic behaviour of structure to solve noise, vibration and harshness problems (NVH). In order to be well predicted the modified dynamic behaviour of structure, the optimisation method via finite element (FE) model updating is used to obtain a reliable and accurate unmodified FE model. The main goal of this research is to change or altered the mode shapes movement of the mild steel bar structure due to the mass modification without shifting the natural frequencies away from unmodified value. In this research, the FE model of the mild steel bar structure was constructed using MSC software and the predicted dynamic behaviour were compared with the experimental modal analysis (EMA) data. The measured data was obtained using an impact hammer testing and roving accelerometers under free-free boundary conditions with data were extracted from LMS SCADAS software. Then, reconciliation process via FE model updating method is carried out in order to reduce the inaccuracy of initial FE model based on the measured data where the initial error has been reduced from 24.81 percent to 7.71 percent. Finally, the updated FE model was used for SDM technique using mass modification. The results reveal that the mode shapes of the structure can be change by manipulating the mass. It is agreed that by adding a reasonable mass with a right position to the structure the mode shapes can be change without shifting the natural frequencies away from unmodified values.

The accuracy of the predicted dynamic behaviour of a structure is highly dependent on the accurate properties used in the analytical model. The predicted results computed from the finite element method used to develop the model are often found not to be in good agreement with the experimental results due to the erroneous assumptions made in the finite element modelling. One way to systematically correct the finite element model is to use model updating methods. The main goal of this study was to systematically improve the predicted dynamic behaviour of a car trunk lid using the modal based updating method. HyperWorks and Leuven Measurement System (LMS) test were used for the finite element modelling and modal testing respectively. In order to evaluate the capability of the modal based updating in improving the finite element model, the natural frequencies and mode shapes computed from the updated finite element model of the trunk lid were compared with the corresponding experimental results. The comparison of the results showed that the total error of 65.48 percent predicted from the initial finite element model of the trunk lid has been successfully reduced to 4.74 percent. In conclusion, modal based updating has been successfully used to reconcile the initial finite element model with the physical model of the trunk lid.

Adopting dynamic substructuring methods to predict the dynamic behaviour of a combined structure is a common practice in the field of structural dynamics. This method has the capability and versatility to combine different sources of data; experimental and analytical, via the frequency based substructuring (FBS) method. This paper investigates the dynamic behaviour of a structure with doubled bolted joints using the frequency based substructuring (FBS) method. In the analysis the substructures are combined in the frequency domain, and the frequency response functions of the substructures are analytically derived and experimentally measured. However, the accuracy of the FBS method is highly dependent on experimental rotational degrees of freedom (DOF) which are always found to be very difficult to measure accurately. Therefore, a new approach - namely single-axis multipoint connection through which the need for the rotational DOF in the FBS method can be neglected entirely is presented in this study. The actual test structure used in this study is an assembled structure consisting of two substructures, a simple beam (numerical model) and an irregular plate steel (experimental model) structure. The FRFs of both substructures are combined via the FBS method. This study reveals that the use of the FBS method with the proposed approach is capable of representing the experimental frequency function response accurately even without rotational degrees of freedom data.

Hydrocarbon based conventional fuels are considered as fast depleting and harmful to the environment as they release poisonous chemicals to the atmosphere. Higher Alcohols and Biodiesel are the most promising alternative fuels widely researched due to their availability, ease of production and environmental benefits. The use of alternative fuels such as alcohol and biodiesel in engines aims to reduce air pollution and energy costs. The most commonly used higher alcohol fuel are bio-ethanol, isopropanol, propanol, ethanol–methanol, butanol, n-butanol, tert-butanol and iso-butanol. The commonly used biodiesel are derived from the waste cooking oil, Pyrolysis oil, Palmoil, Jatropha oil, Karanja oil and Linn oil. The purpose of this review is to reveal engine performance and combustion characteristics using alternative fuels such as alcohol and biodiesel. Also summarized are the effects of alternative fuels on emission properties such as NOx, CO and HC. Keywords: Alcohol, Biodiesel, Alternative fuel, IC engines, Performance, Combustion, Emissions

The wind is air that moves from a high-pressure area to a low-pressure area. Indonesia has the potential of winds that have speeds ranging from 2 m/s to 6 m/s which blow for a period of 6 hours/day. Many researchers have examined what kinds of problems are in the context of wind turbine energy generation. This study discusses the effect of wind speed and variations in the number of turbine blades on the power generated by horizontal wind turbines to rotate generators, case studies on the coast of Banda Aceh. The windmill used is a horizontal turbine propeller type with 5, 6 and 7 blade variations and made from Meranti wood. Electricity data retrieval is done by pairing the generator, so that the data taken in this measurement is in the form of wind speed data (m/s), speed of rotation of the wheel shaft and generator shaft, and generator voltage (V) and electric current generated. Data collection is carried out for 6 days at 3-9 m/s wind speed. The results showed that for wind speeds below 5 m/s it is more ideal to use a small number of turbines and for wind speeds greater than 7 m/s it is better to use a turbine blade with a large number of blades.

A propeller is mainly used for propelling the movement for an aircraft or ship. As it gives major contribution towards the performance of an aircraft or ship, study on propeller structure has become popular. In this study, the dynamic or modal characteristics of propeller structure with different number of blade of the same design are investigated. Modal properties of two blades, three blades and four blades propeller that are obtained through computational analysis are compared after validation of three blades propeller is conducted. It has been observed that the four blades propeller has the lowest nominal value of natural frequencies and shows most mode shapes deflection. The results confirm that as the propeller has more number of blades, it will produce more energy and hence has lower natural frequency.

Nowadays, research on dynamic behavior of structural components is becoming one of the important parts in the design process for any mechanical system. In order to determine the dynamic behavior of a vibrating structure, measurements of the dynamic properties of structure are essential. Free vibration analysis is one of the approaches that apply the finite element method in determining the structure modes of vibration. Each mode is defined by its natural frequency and mode shape. In this paper, the free vibration analysis of grass trimmer was performed using commercial finite element software, such as Ansys®. The importance of determining these vibration characteristics are crucial as grass trimmer is a common machine that exposed to the dynamic and static forces coming from the engine and rotating blade. A long term exposure of grass trimmer's operator may or potentially suffering a risk of hand arm vibration syndrome. The preliminary results of free vibration analysis demonstrated that the grass trimmer experienced a global first bending mode for 1st natural frequency, a global second bending mode for 2nd natural frequency, a local first torsion mode for third natural frequency, and a combination of global and local bending mode for 4th natural frequency. Later, the analyses were further carried out on the modification of the grass trimmer.

There are many ways to control the vibration of plate structure. Conventional approaches that include structural alterations are frequently time consuming and costly. One of the common schemes is using vibration absorber attached to a structure. In this paper, a mathematical model is developed to determine the frequency response of fixed-fixed ends plate with attached vibration absorber. A finite element analysis was performed and compared with the theoretical predictions and showed that there was good resemblance. The results demonstrated that the addition of vibration absorber onto plate can attenuate vibration considerably at a constant frequency.

In this paper, finite element (FE) joint modelling technique for prediction of dynamic properties of sheet metal jointed by tungsten inert gas (TIG) will be presented. I cross section dissimilar flat plate with different series of aluminium alloy; AA7075 and AA6061 joined by TIG are used. In order to find the most optimum set of TIG welding dissimilar plate, the finite element model with three types of joint modelling were engaged in this study; bar element (CBAR), beam element and spot weld element connector (CWELD). Experimental modal analysis (EMA) was carried out by impact hammer excitation on the dissimilar plates that welding by TIG method. Modal properties of FE model with joints were compared and validated with model testing. CWELD element was chosen to represent weld model for TIG joints due to its accurate prediction of mode shapes and contains an updating parameter for weld modelling compare to other weld modelling. Model updating was performed to improve correlation between EMA and FEA and before proceeds to updating, sensitivity analysis was done to select the most sensitive updating parameter. After perform model updating, average percentage of error of the natural frequencies for CWELD model is improved significantly.

Friction stir welding (FSW) of aluminium and magnesium alloys face high demands in automotive and aerospace application due to its advanced and lightweight properties. FSW is an emerging solid state joining process in which the material that is being welded does not melt and recast. The main objectives of this project are to perform model updating based on finite element analysis (FEA) and experimental modal analysis (EMA) of dissimilar material of aluminium alloy AL 7075 and magnesium alloy AZ 31B. Modal properties such as natural frequencies, mode shapes are obtained and compared between FEA and EMA. The discrepancies of first five modes natural frequencies are below than 10% and the model updating have been conducted to minimize the error between two methods. This model updating are based on sensitivity analysis in order to make sure which parameters are given more influence in this structural dynamic analysis. Young’s modulus and Poisson’s ratio both materials are selected in the model updating process. After perform model updating, total average error of the natural frequencies of dissimilar friction stir welding plate is improved significantly.

The objective of this paper is to present frequency response function (FRF) based updating as a method for matching the finite element (FE) model of a laser spot welded structure with a physical test structure. The FE model of the welded structure was developed using CQUAD4 and CWELD element connectors, and NASTRAN was used to calculate the natural frequencies, mode shapes and FRF. Minimization of the discrepancies between the finite element and experimental FRFs was carried out using the exceptional numerical capability of NASTRAN Sol 200. The experimental work was performed under free-free boundary conditions using LMS SCADAS. Avast improvement in the finite element FRF was achieved using the frequency response function (FRF) based updating with two different objective functions proposed.

Thin metal sheets are widely used to fabricate a various type of aerospace structures because of its flexibility and easily to form into any type shapes of structure. The riveted joint has turn out to be one of the popular joint types in jointing the aerospace structures because they can be easily be disassembled, maintained and inspected. In this paper, thin metal sheet components are assembled together via riveted joints to form a simplified model of aerospace structure. However, to model the jointed structure that are attached together via the mechanical joints such as riveted joint are very difficult due to local effects. Understandably that the dynamic characteristic of the joined structure can be significantly affected by these joints due to local effects at the mating areas of the riveted joints such as surface contact, clamping force and slips. A few types of element connectors that available in MSC NATRAN/PATRAN have investigated in order to presented as the rivet joints. Thus, the results obtained in term of natural frequencies and mode shapes are then contrasted with experimental counterpart in order to investigate the acceptance level of accuracy between element connectors that are used in modelling the rivet joints of the riveted joints structure. The reconciliation method via finiteelement model updating is used to minimise the discrepancy of the initial finite element model of the riveted joined structure as close as experimental data and their results are discussed.

There are a lot of study regarding on the aircraft components. One of the critical components for an aircraft would be the wings. The wing structure of an aircraft is one of the complex structures of a designed aircraft. This paper is about identifying the modal properties which are the mode shape and the corresponding natural frequencies of the aircraft wing structure. The modal properties of the wing structure would be compared for two different materials applied towards the wing structures which are the aluminium alloy AA-7075-T6 and AA-2024-T3 which currently being widely used by the aircrafts. The study for this aircraft wing structure would be using the approach of finite element analysis (FEA) method. The 3D model is design by using SolidWorks. The modal properties are identified with the help of MSC PATRAN and MSC NASTRAN. The results obtained for both materials for 10 mode shapes are compared and it could be observed that AA-7075-T6 are much lower compared to AA-2024-T3. Hence, from the result, AA-7075-T6 is more suitable to be used for the wing structures.

Automotive radiator played an essential role as a heat exchanger that exchange the circulated heated coolant inside the engine compartment to return into its ambient temperature. Radiator cooling fan that attached at the back of radiator, is a device that work to regulate the coolant temperature when the heated coolant is passed inside the radiator tubes. It produces external flow of air that passes through the fins and tubes of the radiator. However, this external flow contributes high noise level into the system. In consequence of this risk, a detailed experimental study on noise analysis to identify the location of maximum sound pressure level (SPL) generated by variations of cooling fan speed by using sound intensity mapping method is presented. Ethylene Glycol (EG)-water based was used as working fluid operate with engine temperature range from 80 to 90 °C. The cooling fan speed of radiator cooling fan were varied from 750 to 1250 rpm and the water flowrates were 8.0, 11.0, and 14.0 l/min. The results indicate that the noise level is increasing with the fan speed. However, there is no significance difference of change in coolant flow rate and type of coolant fluids to the noise level. The location of maximum sound pressure level is identified and the higher SPL value most located on the blade trailing edge of the suction surface with highest SPL value of 81 db for 1250 rpm fan speed. The project delivers the reliable input for the engineering practice to reduce automotive radiator noise level.

Along with the development of alternative fuel to replace the usage of petroleum-derivatives, the vibration in the diesel engine has become one of the main focus by researchers recently. The biodiesel has been investigated numerously since the application does not need any modification of the engine and with the different fuel properties, the biodiesel can enhance or deteriorates the engine. Hence, this study will be carried out to investigate the effect adding butanol in two different biodiesel blends by using vibration analysis. The vibration level will be determined in velocity term in RMS by using uniaxial accelerometer. The results indicated that the B10Bu10 blend shows a better reduction in vibration level with the decrement more than 30% for both speed in 25% load while in the 50% load, the decrement was observed to be 13.46% for 1800 RPM and 22.9% for the 2100 RPM. Finally, it can be conclude that the usage of biodiesel with the additional of butanol can improve the vibration level in the diesel engine, however, with an additional volume of biodiesel in the blend tends to increase the vibration level in certain condition.

Composite plate structure is broadly used in engineering structures for automotive and aerospace applications. Furthermore, the problem in vibrational is one of the industries main challenges. Composite materials are frequently used in industry for weight and cost reduction to enhance mechanical properties in structural components. This research aims to execute a composite plate structure model updating procedure. Through finite element analysis (FEA) and experimental modal analysis (EMA), modal parameters such as natural frequencies, mode shapes, and damping ratios are collected. Composite plate structure is set to be free-free boundary condition and node equivalence is done in the surface plate area. Correlation is executed between these two data sets. The discrepancies in natural frequencies between FEA and EMA were reduced with the selected parameters identified to perform structure updating model using sensitivity analysis.

This study focusses on experimental modal analysis (EMA), finite element analysis (FEA) and model updating. The result of FEA and EMA will be validated and analysed. Then, the study extended to the early stage of model updating by assuming that the riveted dissimilar plates is a rigid body instead of two dissimilar plates. These modal parameters are crucial in providing various periods at which it will naturally resonate to avoid the structure continue to resonate and experience structural damage. Modal parameters of the dissimilar plate with rivet joint which include natural frequency and mode shapes were determined through EMA and FEA. Comparison of experimental data and the simulation data reveals a good correlation between the values of natural frequency. Minor discrepancies of the percentage of error between EMA and FEA are acceptable with the percentage of error is within the range of 0.4% to 13%. Furthermore, the conducted model updating able to reduce to an error range of 0.03% to 0.1%. Through this study, the best way of conducting finite element analysis and model updating for dissimilar plate material with rivet joint is also determined.

Topic of crashworthiness is gaining popularity as vehicle safety is becoming main concern to the vehicle manufacturers worldwide. Due to this factor, energy absorbing members on vehicle such as crash box is researched by many which lead to various strategies of design optimization has been carried out in order to seek a good energy absorber on vehicle. Among the popular method of determining the crash performance of a structure is by using dynamic analysis in computational finite element model (FEM). However, since finite element analysis (FEA) is only an approximation method which in many cases can be less reliable, model updating method is often suggested to improve its reliability. This study seeks to investigate the crash behaviour of initial and updated crash box model. The velocity of impactor, the deformation, collapse distance and energy transferred to the two models of crash box are compared. The findings show that the initial and updated model of the crash box in this study, do have different crash behaviour. However, the difference level is relatively small. The investigation on the method of validation for the updated model in terms of crash behaviour is highly recommended.

Measuring the dynamic behaviour of a structure made from light thin steel sheets becomes arduous as a result of the double impact, local modes and mass loading issues which lead to inaccurate results. In addition, the attachments of accelerometers, selection of suspension types and methods of excitation adopted to the measurement greatly affect the quality of the experimental results. The aim of this paper is to present detailed procedure for the experimental setup of a welded structure made from thin steel sheets. A hat shaped plate and flat plate connected together by several laser spot welds were used for the demonstration of the experimental modal analysis. The laser spot welded hat-plate structure was tested under free-free boundary conditions using impact testing with roving accelerometers and an LMS Test Lab. This work revealed that the proper procedures used for the experimental setup would help dynamicists enhance and improve the quality of the measured results of frequency response function and the results could be confidently used for the validation purposes and updating analytical models.

An experimental study was carried out for measuring vibrations, noise and combustion characteristics associated correlations using a four-cylinder spark ignition engine. This study aims to investigate the effects of vibrations and noise on spark-polishing machines that are triggered by pure gasoline. This test runs at 15% engine load and 20% with engine speed 1000-2200 rpm at intervals of 300 rpm. The measurement of engine vibration in pistonic uses PCB Piezotronics ICP® Accelerometer (352C22). Overall tests that have been carried out for 20% loads at 1900 and 2200 maximum vibrations, the velocity is 0.214 and 0.234, compared to 0.617 and 0.562 for 15% loads. From the results of engine vibration analysis, it can be reported that increasing engine speed and the load is given engine vibration can significantly decrease. Generally, noise increases for all samples tested; however, reduced noise is recorded when speed and engine load increase. This observation is also consistent with other observations related to vibration and combustion noise, heat release rates, and ignition delays.

Experimental analysis is often viewed as an important source of reference compared to finite element due to the accuracy of giving reliable data. Currently, finite element analysis is widely used as an early adoption in development, hence trusting the finite element data is crucial for the user. Finite element analysis often shows discrepancies to the test result. The complexity of the joints (bolted) might cause the discrepancies to occur. This study aims to reduce the discrepancies between the experimental and numerical analysis on a frame structure with bolted joints by model updating. Model updating is a process of making adjustment to certain parameters of finite element model to reduce discrepancy between analytical predictions of finite element analysis (FEA) and experimental results. Modal properties (natural frequencies, mode shapes, and damping ratio) of a frame structure with bolted joints are determined using both experimental modal analysis (EMA) and finite element analysis (FEA). Both data obtained is correlated before optimising the properties with sensitivity analysis. Joint strategy of this paper is focusing on RBE2, CBAR and CELAS element. CELAS was selected to represent the bolted modelling due to its lowest percentage average of 2.03% compares to CBAR 6.55% or RBE2 3.56%. Selected parameters were identified by performing a sensitivity analysis and the discrepancies was reduced by performing model updating procedure.

In pursuance of deciding the dependability of data gathered by testing a finite element modal in the software version, experimental data is frequently used for validation. On account of finite element analysis, it can sometimes be considered as inaccurate particularly when applied to the complex structure, for example, a propeller blade. This is because of challenges that may happen in the modelling of joints, boundary conditions, and damping of the structure. In this research, a procedure of correlation and validation of the model-based test plan with modal testing results was conducted. Modal properties (normal frequencies, mode shapes, and damping ratio) of a propeller blade structure were resolved by using both test experimental modal analysis (EMA) and finite element analysis (FEA). Correlation of both sets of data was performed for validation. It created the impression that there was a noticeable estimation of error between those two sets of data. Small discrepancies of percentage error of obtained natural frequency for FEA and EMA makes both of the methods can be applied to determine the dynamic characteristic of the propeller structure.

The research was conducted to investigate the quality of knives the material and the forging process against wear resistance. The forged material is AISI 1050 steel, AISI 4340 steel, AISI L-6 steel, and JIS SUP 9 steel. The manufacturing of the knives ware done by heating the material to a temperature ranging from 900-950°C then forged repeatedly manually until the temperature drop in between 650-675°C. Heating and forging are carried out several cycles to form a knife. Hardening was done by heating the knives to reach austenite temperature by flame hardening method, then quenching using water cooling media. research of wear resistance was done on the sharp side by using an actuator tribometer pin-on-plate. The results showed that wear and tear were influenced by the material and the treatment. The flame hardening process can be reduced the wear rate, the wear rate found on AISI 1050 steel knives is 5.439 x 10−4 mm3/Nm after being forged, while the lowest wear rate was found on AISI L-6 steel knife which ware 2.44 x10−5 mm3/Nm after flame hardening. The flame hardening process can reduce the wear rate, highest wear rate found on AISI 1050 steel knives ware 5.439 x 10−4 mm3/Nm after being forged, while the lowest wear rate was found on AISI L-6 steel knife which is 2.44 x 10−5 mm3/Nm after flame hardening. Therefore, it can be conclude that traditional knife quality especially the wear resistance can be improved by optimizing the heat treatment schedule.

A single cylinder diesel engine is an internal combustion engine; this machine is typically a compression ignition engine, fuel ignition through a high one made for compression of fuel and air mixtures. This study conducts a modelling with one dimension on a single cylinder four-stroke diesel engine and analyses the simulation results with experimental data. The simulation model covers the entire engine cycle consisting of compression, power, intake, and disposal for different engine speeds such as 1000, 2000, 3000, 4000, 5000, and 6000 rpm. Simulation modelling was done for the development of computation using software GT-POWER. The result of this modelling measures the accuracy level of machine parameter data from the modelled simulation. Based on the simulation results with modelling the machine, the data accuracy rate reached 90% in various cases tested with different engine speeds. Furthermore, the results also show that the modelling provides accurate data and can be used in the industry as a tool for development of different machines in the future.

Bulletproof vest serves as a barrier and simultaneously absorbing the impact energy of a projectile shot from a firearm so it could not injure the users. Manufacture of lighter bulletproof vests with good absorbent of impact energy, is expected, because it supports the mobility and safety of its users. In this study, a composite composed of an epoxy matrix with a 16% Hollow Glass Microsphere (HGM) and carbon fiber reinforce to be implemented in a bulletproof vest. The objective of this research is to analyze the bullet-proof vests made of epoxy matrix composites with reinforcement in the form of HGM and carbon fiber through simulation with finite element method. Simulations with Ansys conducted in accordance with NIJ Standard 0101.06 from the U.S. Department of Justice, where the projectile initial velocity of 426 m/s for the category IIIA class weapon with a kinetic energy of projectile amounted to 528.37 Joules. The simulation with Ansys was performed by varying the thickness of bulletproof vests to obtain optimum thickness. The outcome of this research is a bulletproof vest that absorbs the impact energy of the projectile, so that the energy transmitted to the body is smaller than 170 Joules. Having obtaining the optimum thickness of bulletproof vest, an experimental verification will be performed to validate the simulation results. In the simulation results showed that a bullet proof vest with a thickness of 20 mm has been able to meet the standards of Major General Julian S. Hatcher, a U.S. Army ordnance expert with great energy generated at 138.77 Joules.

Performance on diesel engines with various combustion chamber sizes and fuel injection require effective handling so that the root combustion process in large diesel engines is timely. This study compares the experimental data with simulation through the single cylinder diesel modelling using GT-Power software. This simulation utilises parameters in diesel engines of 1000 and 2000 rpm speeds with methanol and diesel fuels. This modelling aims to develop a single cylinder diesel engine by measuring all components on the machine. The comparison between the simulation results and experimental data indicate similar collaboration with a difference about 5%–10%. Based on the results, the modelling of developed machine shows that simulation using GT-Power software is able to successfully validate all machine data parameters up to 90%. This simulation result can be expressed accurately similar to the experimental results and can be used as standardization for a single cylinder diesel engine design.

Vibrations are always undesirable, wasting energy besides producing noise. In this case, beams which are prominent component in most engineering having no exemption from the vibration effect when imposed by dynamic loading. One of the approach to attenuate vibration of a structure is by having a spring-mass-damper (SMD) system or typically known as vibration neutralizer attached to the vibrating structure. This method is more promising as it does not contribute significant additional energy to the structure. The work presented in this paper describes the frequency response (FRF) of a simply supported beam with an attached SMD system. A mathematical model of a beam was at first developed in the study which was further derived to include the attachment of SMD system. In order to transform the derived equations into a form of graph that can be analysed, Matlab® software was used. The outcome from Matlab® shows that the attachment of SMD onto beam attenuates its vibration significantly. The result also displays a good resemblance FRF when compared with numerical finite element analysis of Ansys®. It is expected that the theoretical derivation demonstrated in this paper provide a helpful reference to future researchers who endeavour to find equations of a simply supported beam with an attached SMD system as well as for a vibration control study.

Friction stir welding of aluminium alloys widely used in automotive and aerospace application due to its advanced and lightweight properties. The behaviour of FSW joints plays a significant role in the dynamic characteristic of the structure due to its complexities and uncertainties therefore the representation of an accurate finite element model of these joints become a research issue. In this paper, various finite elements (FE) modelling technique for prediction of dynamic properties of sheet metal jointed by friction stir welding will be presented. Firstly, nine set of flat plate with different series of aluminium alloy; AA7075 and AA6061 joined by FSW are used. Nine set of specimen was fabricated using various types of welding parameters. In order to find the most optimum set of FSW plate, the finite element model using equivalence technique was developed and the model validated using experimental modal analysis (EMA) on nine set of specimen and finite element analysis (FEA). Three types of modelling were engaged in this study; rigid body element Type 2 (RBE2), bar element (CBAR) and spot weld element connector (CWELD). CBAR element was chosen to represent weld model for FSW joints due to its accurate prediction of mode shapes and contains an updating parameter for weld modelling compare to other weld modelling. Model updating was performed to improve correlation between EMA and FEA and before proceeds to updating, sensitivity analysis was done to select the most sensitive updating parameter. After perform model updating, total error of the natural frequencies for CBAR model is improved significantly. Therefore, CBAR element was selected as the most reliable element in FE to represent FSW weld joint.

In order to determine the reliability of data gathered using computational version of finite element analysis, data obtained through experimental work are always utilized. In field of dynamic analysis, experimental data is often viewed for having better accuracy giving the availability of reliable data acquisition and measuring equipment. On the other hand, in case of finite element deviation, it can sometimes be considered as inaccurate especially subject to complex structure such as body-in-white. This is due to difficulties that might occur in modelling of joints, boundary conditions and damping of the structure. In this study, a process of comparison and validation of model based test design with modal testing results was conducted. Modal properties (natural frequencies, mode shapes, and damping ratio) of a body-in-white structure were determined using both experimental modal analysis (EMA) and finite element analysis (FEA). Correlation of both sets of data was performed for validation. The discrepancies that appear after correlation was then reduced by performing model updating procedure. The results presented here may demonstrate the effectiveness of model updating technique on improving the complex structure such as body-in-white structure.

Friction stir welding (FSW) is a welding process that widely used as a solid state joining process for producing welded structure of similar and dissimilar materials such as aluminum alloy, magnesium etc. FSW process has expanded rapidly in industries including aerospace, automotive and maritime due to several advantages compared to other fusion welding. In this paper, experimental modal analysis (EMA) and normal mode finite element analysis (FEA) of the FSW welded joint structure of materials AA6061 and AA7075 will be carried out to identify dynamic properties. Rigid Body Element (RBE2) in MSC NASTRAN/PATRAN is used to model the welds and their compatibility for representing FSW welded structure also being identified. Model updating is performed to minimize the discrepancy between EMA and FEA. Model updating will be acted as an optimization method and is being presented using the structural optimization capability. Finite model updating could be done in individual components and welded structure. RBE2 connecting element can be used to represent friction stir welding with good accuracy.

Motorcycles built from multiple materials such as steel and aluminium that formed a welded of beams to construct the chassis. The frame is designed by combining the part-by-part saddle, handlebar and wheel that are attached together. In this study, the identification of structural dynamics study for motorcycle chassis was conducted to identify modal properties such as natural frequencies and mode shapes. This could be achieved by using two different analysis approaches; Finite Element Analysis (FEA) and Experimental Modal Analysis (EMA). For FEA analysis, 3D modeling of the chassis frame is needed and modelled using CAD software. Normal mode analysis was run on modelled structure to determine modal properties after meshing type and properties of materials declared. Impact hammer testing using roving accelerometer method was conducted for EMA study and comparison of modal properties with FEA is carried out. Discrepancies that appeared after correlation among two approaches attempted to be reduced by performing model updating procedure and it was successfully reduced the average percentage of error to be less than 10%. The results show that the model updating was an effective technique for improving the discrepancy that may exist due to modelling issue and material properties prediction in FEA. This study clearly shows that model updating technique is an effective way of reducing the discrepancies between EMA and FEA.