The effects of absorber attachment location on vibration response of simply supported plate

Vibration analysis of thin walled structure has been an active research in engineering fields. This paper proposed to investigate the application of vibration absorber (VA) attached to the simply supported plate (SSP) in order to suppress the structural vibration. Two major factors influence on vibration reduction of late are investigated in term of the attachment location of vibration absorber and the number of absorber applied on structural dynamic of the plate. Finite element software of ANSYS APDL was performed to measure the dynamic response of plate. The results found that the best positioning vibration absorber are at the location of 0.35 m of x-axis and 0.40 m of y-axis which can attenuate the vibration along the frequency band. Numerical result also presented that when attached multiple absorber, the vibration reduction of plate provide larger suppression to SSP which average reduction almost 80% over the frequency modes. This study conclude that right position and number of absorber can be the major contribute to suppress vibration on a plate structure more effectively

Application Of Dynamic Correlation Technique And Model Updating On Truck Chassis

Truck chassis is a major component in a vehicle system. It is often identified for refinement in order to develop vehicles with reduced cost and weight. Nowadays the process of chassis design in the automotive industry has been significantly refined with the high capabilities of advanced computer aided design and engineering tools,. The application of FEA such as structural modification and optimization is used to reduce component complexity, weight and subsequently cost. Because the level of model complexity can be high, the opportunity for error can also be high. For this reason, some form of model verification is needed before design decisions made in the FEA environment can be implemented in production. This paper looks into the application of dynamic correlation techniques for verification of the FEA models of truck chassis. The dynamic characteristics of truck chassis such as the natural frequency and mode shape were determined using finite element method. Experimental modal analysis was carried out to validate the FE models. Initial results from both analysis show that the truck chassis experienced 1st torsion mode for 1st natural frequency, 1st bending mode for 2nd natural frequency, 2nd torsion mode for 3rd natural frequency and 2nd bending mode for 4th natural frequency. However there is a small discrepancy in terms of frequency. Thus, the model updating of truck chassis model was done by adjusting the selective properties such as Modulus Young and Poisson ratio in order to get better agreement in the natural frequency between both analysis. Finally, the modifications of the updated FE truck chassis model was suggested such as by considering adding the stiffener. The purpose is to reduce the vibration as well as to improve the strength of the truck chassis

Moisture absorption and diffusivity of epoxy filled layered-structure nanocomposite

This paper studies moisture absorption and diffusivity of epoxy reinforced layered structure nanocomposites and its effect on fracture toughness. Two different types of layered fillers employed in the study were clay and graphene platelets, in which both surface layers were unmodified and modified by characterized by swelling analysis and fracture toughness measurement. The outcomes surfactant. The nanocomposites were showed that the moisture absorption and diffusivity decreased with the addition of layered fillers. It was found that the modified graphene platelets and clay outperformed the unmodified layers and neat epoxy in terms of reduction of moisture absorption and diffusivity. The modified graphene platelets reduced the moisture uptake and diffusivity about 30% and 33%, respectively compare to neat epoxy, thus indicates its outstanding performance in barrier applications. However, once the nanocomposites were swelling in the water for 5 days, it is noticed that the fracture toughness of nanocomposites were reduced significantly about 35% in average. Nevertheless, the modified graphene platelets still display the better performance compare to the other samples although there was reduction of fracture toughness

Study of vibration absorbers using epoxy reinforced natural fibers

It is well known fact that vibrations contribute to excessive wear, fatigue failure and other premature failure of machine components. Thus, various methods have been applied to control these vibrations. One of the commonly used is vibration absorber. The aim of this paper is to explore the potential of epoxy reinforced natural fibers as an alternative material for vibration absorber. Both mechanical properties and dynamic characteristic of the composites are investigated through tensile test and transmissibility test, respectively. Two types of natural fibers were selected for the study; coconut coir and pineapple leaf. The results show that the tensile modulus of composites increases with the increase of fiber content, although the strength was found decreases. This reduction indicates an ineffective stress transfer between the fiber and matrix. From the tensile test result, 20 vol% of pineapple leaf fiber was found to be the optimum fraction, in which afterward was employed for fabrication vibration absorber. Meanwhile, from the transmissibility test, it was noticed that when base excitation increases, the resonance peak and attenuation frequency were changed to the lower value. The fixed-fixed end beam with attached composite vibration absorbers showed that the resonance amplitude of the beam decreased significantly. More absorbers attached on the beam produce better result in attenuating the global structural vibration

Dynamic analysis of friction stir welding joints in dissimilar material plate 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

Influence of Fiber Volume Fraction on the Tensile Properties and Dynamic Characteristics of Coconut Fiber Reinforced Composite

The utilization of coconut fibers as reinforcement in polymer composites has been increased significantly due to their low cost and high specific mechanical properties. In this paper, the mechanical properties and dynamic characteristics of a proposed combined polymer composite which consist of a polyester matrix and coconut fibers are determined. The influence of fibers volume fraction (%) is also evaluated and composites with volumetric amounts of coconut fiber up to 15% are fabricated. In this work, the tensile test was carried out to determine the strength of material, while modal testing was used to obtain the dynamic characteristics of the composite material. Results were found that the strength of the composites tends to decrease with the amount of fiber, which indicates ineffective stress transfer between the fiber and matrix. The dynamic characteristic of composite was also having a same effect where the natural frequency decreased with increase of coconut fiber volume. However the damping ratio was found to be increased by the incorporation of fiber. When higher fiber content of 15% was used, the damping ratio shows the maximum value for almost all the frequency mode. It was observed that the effects of reinforcing polyester matrix with coconut fibers lead the composites more flexible and easy to deform due to high strain values and low stiffness. In fact, it may also be used to reduce high resonant effect

Thin film flow of non-newtonian third grade fluid down an inclined plane by variation of parameter method

In this study, a non-Newtonian third-grade fluid flow down an inclined parallel plate held horizontally against each other are investigated. As the nonlinear differential equation which governs the flow model can be obtained by using the conversation of laws, the Variation of Parameters Method (VPM) is then applied to solve the aforementioned differential equation. The proposed VPM is applied without any discretization, perturbation, transformation or restrictive assumptions and is free from round off errors and calculation. Analytical solution solved by Runge-Kutta numerical solution and the VPM show excellent agreement. Effects of flow parameters β and m on the velocity field are demonstrated graphically with comprehensive discussions. Numerical results reveal the complete reliability of the proposed VPM

From clay to graphene for polymer nanocomposites-a survey

The development of aerospace and automotive in- dustries requests lightweight, high-performance materials, and polymer nanocomposites are ideal candidates in this case, which is shown by the increasingly more publications in this research field over the past two decades. However, the perfor- mance of nanocomposite not only depend on the properties of their individual constituents, but on their morphology and surface characteristics of fillers as well. Selections of nanofillers geometries, e.g. particulate, fibrous or layered have a tremendous influence on the properties of nanocomposites and their processing methods. In this paper, we review the chronological works performed in the field of polymer nano- composites, in particular epoxy nanocomposites reinforced with layered fillers, such as clay and graphene. Surprisingly layered fillers are commercially available and more cost- effective than nanoparticles and carbon nanofibres, and these make them to the most extensively studied fillers that can be geared toward future applications, particularly in large-scale polymer nanocomposite production

From clay to graphene for polymer nanocomposites-a survey

The development of aerospace and automotive in- dustries requests lightweight, high-performance materials, and polymer nanocomposites are ideal candidates in this case, which is shown by the increasingly more publications in this research field over the past two decades. However, the perfor- mance of nanocomposite not only depend on the properties of their individual constituents, but on their morphology and surface characteristics of fillers as well. Selections of nanofillers geometries, e.g. particulate, fibrous or layered have a tremendous influence on the properties of nanocomposites and their processing methods. In this paper, we review the chronological works performed in the field of polymer nano- composites, in particular epoxy nanocomposites reinforced with layered fillers, such as clay and graphene. Surprisingly layered fillers are commercially available and more cost- effective than nanoparticles and carbon nanofibres, and these make them to the most extensively studied fillers that can be geared toward future applications, particularly in large-scale polymer nanocomposite production

Hazard identification, risk assessment and risk control: a study at construction site

Occupational Safety and Health Act (OSHA) is an Act to make further provisions for securing the safety, health and welfare of persons at work, for protecting others against risks to safety or health in connection with the activities of persons at work, to establish the National Council for Occupational Safety and Health, and for matters connected therewith. This study focuses on infrastructure construction in Pagoh Education Hub. In present days, despite of knowledge in OSHA act, workers often proceed the work without considering any safety precaution or act at workplace as stated in OSHA Act. Due to ignorance of workers and employee on OSHA Act, workers are exposed to danger and hazard at their workplace causing them minor or worst fatal injury. The data collection was carried out through site investigation using Preliminary Hazard Analysis (PHA), HIRARC form and interview session with several workers in the constructio. The main objective of this study is to support the idea to coordinate and redefined the practice of occupational safety and health as workers discipline at their workplace based on existing potential hazard. This study was conducted to identify the hazard that occur at the workplace and analyse the safety precaution taken by the workers and employer to avoid accidents. As a result, this study listed several suggestions to improve the practice of occupational safety and health among workers in the workplace