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Despite of the emergence of the hybrid and electric vehicle in the automotive sector recently, the power that constantly delivered by the petroleum-based engine still be the one of the important factors that was considered by the customer. Even so, the automotive manufacturers in the 20s are making a big move by producing the engine that possessed the ability to use the biodiesel up to 20 % of blending ratio since the biodiesel addition does not owe to much drop of engine performance. As the noise emission highly contribute to the environmental pollution apart from the poisonous gases released by the fossil fuel usage, this study was carried out to identify the effectiveness of biodiesel in reducing the noise generated by the engine using multiple blend ratio. The Sound Power Level (SPL) method was used to investigate the maximum noise produced together with the location of the noise generated by the engine when using different blend ratio. Various engine speed and load were used in order to give the most similar condition to the real-working engine. Generally, the results indicated that the changes of engine speed and load could owing to the gradually increment of noise level in the engine, nevertheless, the increment was reported to be partially for some of the setup with the Pure Diesel (D100) usage. With the biodiesel usage, it is notable that the highest value was obtained by the B10 located at the flywheel and dynamometer with the value of 100.91dB and on the contrary, the lowest value could be obtained by the D100 with the value of 77.63dB located at the cylinder head. As can be summarized, different proportion of biodiesel could vary the noise level due to the changes of the fuel properties that influenced the combustion, mechanical and gas-flow noise in the engine. [ABSTRACT FROM AUTHOR]

Vehicle design is the most significant factor in determining and decreasing the impact of accidents and improving road safety. Therefore, studies on the safety components of vehicles should be focused primarily on crash boxes. This study is focusing on the crash box structures that straightforwardly experience the vibrational phenomena. This project was conducted to determine the modal property such as natural frequencies of car crash box structure by performing the Experimental Modal Analysis (EMA) on several specimens. Impact hammer test applied and the analysis using ME'Scope VES to identify the modal properties. For this purpose, the experimental modal test setup has been established. An impact hammer test made it possible to obtain Frequency Response Function (FRF). The FRF were curve fitted in order to obtain the mode shapes and natural frequencies. The modal parameters found from both numerical analysis and experimental testing methods are compared. The modal behaviour of the crash box structure would be analysed for nine different pieces with different fabrication through same process of manufacturing applied towards the crash box structures which is the aluminium alloy 6061 that is commonly used in automotive industry. These nine-sample result will be analysed from the deviation of the result of the modal properties. [ABSTRACT FROM AUTHOR]

A-frame structure is prevalent as an engineering structure as it is considered as the foundation for many other structures such as buildings, vehicles, communication towers and others. The study on frame structure has gained a lot of interest in the field of material application, stability, joints application and many other topics. This study aims to investigate the modal behaviour of a frame structure with different sets of bolted joints, materials and also different boundary conditions.The frame structure was put under different boundary conditions and the structure was modelled by incorporating different sets of bolts. The effect of the changes towards the modal behavior (natural frequencies and mode shapes) was analysed. The modal analysis was conducted computationally by using the finite element software package MSC. Natran/Patran in normal modes analysis (SOL103). From the analysis, it was found that the frame structure under free-free boundary conditions produced lower natural frequencies than the structure with fixed at the bottom. The value of natural frequencies also is lower when single bolt was assigned at each of the joint location on the frame structure compare to when the bolts were doubled at joint area. Other than that, between free-free and fixed-free boundary condition, fixed-free is more rigid than free-free condition and for extra rigidity of frame structures, double bolted model is better than single bolted. From the results, the better idea in order to make frame structure is by made up of steel, double bolted it and make it fixed-free condition [ABSTRACT FROM AUTHOR]

This paper focusing on the joint modelling techniques of Finite Element (FE) to model a light dissimilar structure with bolted joints made up of bolts and nuts. The usage of a model update strategy is employed to improve the FE model's dynamic behaviour. In the FE model, a joint strategy is constructed using three different types of element connectors: CBAR, CBEAM, and CFAST. The modal parameters of a bolted joint structure made of dissimilar materials AZ31B and AA6061 were determined using Finite Element Analysis (FEA) and Experimental Modal Analysis (EMA) in this research (natural frequencies, damping ratio, and mode shapes). The number of elements, number of nodes, and total percentage errors of respectively initial FE model, when compared to EMA results, were evaluated. In comparison to the others, the CBAR element was chosen to represent a fastener joint for the updating process due to its accurate prediction of mode shapes and inclusion of updating parameters. Sensitivity analysis is performed before the updating process to choose the most sensitive parameter for updating purposes. In the FE model updating procedure, MSC Nastran's optimization technique is applied. Therefore, the discrepancies between FEA and EMA have been decreased. When compared to the measured equivalent, the percentage of error for the modified CBAR model drops from 4.37 percent to 2.71 percent. As a result, it is discovered that updating the FE model is a systemic and efficient technique in conducting the appropriate FE model in recreating the genuine structure. [ABSTRACT FROM AUTHOR]

Modal analysis is widely used in order to identify the dynamic behaviour which are natural frequencies and mode shapes of a structure through the approach of experimental as well as finite element analysis. Beam which is commonly used in the industries of construction had gained the interest as the topic of research. This project intended to investigate the vibration analysis on dissimilar cantilever beam structure with different joints which will be conducted through finite element analysis (FEA). In FEA, cantilever beam structure is modelled by using dissimilar materials which is stainless steel 304 and aluminium 6061. Two types of element connector which are bar element (CBAR) and beam element (CBEAM) are modelled in FEA and applied to replicate real connections (welded joint and riveted joint). Besides, several element sizes are computed for mesh convergence analysis and the presence of crack is modelled and analyzed. Finite element modal analysis is simulated to determine modal properties. Natural frequencies of element connectors and real connections are compared to the equivalent rigid body method. From the FEA, it is found that the discrepancies of errors that occurred between CBAR with theoretical welded joint and CBEAM with theoretical riveted joint have proved that such joint element strategy best in representing real connectors. Thus, CBAR and CBEAM are compatible to resemble the real connection in the beam structure. The best element size is observed as well as the comparison between uncrack and crack beam structure is carried out. [ABSTRACT FROM AUTHOR]

This paper would focus on the structure of aluminium alloy spot welded crash box with the trigger mechanism as the structure are widely studied for its crashworthiness as well as the location of the structure itself at the car chassis which are subjected to dynamic loading of the car. Aluminium alloy is broadly used in the car body-in-white due to the properties of sufficient strength, better formability, light weight as well as good crashworthiness properties while welded joints are also extensively used as a joining of car components. As this study use both approach of finite element and experimental, in order to validate the finite element analysis (FEA) data, it would be correlated with the experimental approach and further optimization of the finite element (FE) modelling would be made to reduce the discrepancies of data. In this study, the model updating method which update the most sensitive modal parameters would be used towards the crashworthiness analysis to observe for any significant difference with the initial crashworthiness analysis. Finite element modal analysis would be done for the crash box structure and the data would then be correlated with experiment modal analysis (EMA). The same finite element modelling would also be used for the finite element crashworthiness analysis. For modal analysis of both approach, model updating was done to reduce the discrepancies and the sensitive modal parameters were identified and it were used in the new crashworthiness analysis. From the study, it could be observed that the crashworthiness output of the crash box structure with the updated model were different from the initial crashworthiness output in term of its total energy absorbed. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]