Hanizah Ab Hamid

Magnetorheological Elastomers: A Review

This present paper reviews on the material compositions of Magnetorheological elastomer (MRE) as presented by researchers. As the article review, this paper much focuses on the selection of the material in the MRE ingredients. MRE has been known as a new kind of smart material over past decades. MREs offer innovative solutions for various applications in the engineering field since the rheological properties of MREs can be controlled by an external magnetic field. The characteristic responses of MRE are influenced by many factors such its elastomer matrix, the size, distribution, composition, percentage volume of filler particles and so on.

Influence of Different Fillers on the Tensile Properties of 50/50 NR/NBR Blend

This paper reviews the relationship of the effect of different fillers used in the natural and nitrile rubber compounds on the tensile properties. The use of fillers in the rubber compounds is well known in order to modify and improve their properties. Thus, four different grades of carbon black and non-carbon black fillers were used to achieve the aim of the study. A comparison between carbon black and calcium carbonate system leads to further scientific findings for the understanding of the tensile properties of filled rubber compounds. The tensile properties of the five samples were investigated by using a Tensile Instron Machine. Five test pieces were tested for every sample at a stretching rate of 500 mm/min at standard laboratory temperature. Then, median values of the five test pieces of each sample were calculated. As the conclusion, different types of fillers results to different properties of the elastomers. Carbon black fillers can be proved to have better tensile properties compared to non-carbon black fillers. The best filler with the highest tensile properties was N220 with 23.63 MPa and elongation at break at 638.63 %.

Dynamic mechanical behavior magnetorheological nanocomposites containing CNTs: A review

Carbon nanotubes (CNTs) based polymer composites have variety of engineering applications due to their excellent mechanical, electrical, chemical, magnetic, etc. properties. This paper is an attempt to present a coherent yet concise review of as many of these publications as possible on the mechanical aspect of the Magnetorheological Elastomer (MRE) composites with the addition of multi-walled carbon nanotubes (CNTs). The dynamic mechanical response of the MR nanocomposites to applied magnetic fields has been investigated through dynamic mechanical analysis. It is found that a small amount of carbon nanotubes can effectively improve the mechanical performance of conventional MR elastomers. In summary, multi-walled carbon nanotubes reinforced magnetorheological composite has been developed to take advantage of both the smart MR technology and outstanding properties of carbon nanotubes. Furthermore review is also carried out on the capability of carbon nanotubes to impart the stiffness and damping performan...

A Review of Magnetorheological Elastomers: Characterization Properties for Seismic Protection

Magnetorheological (MR) materials are belong to the group of smart materials that can be significantly altered in a controlled under the influence of an external stimulant which by changing their viscolesatic properties due to stress, pH level, moisture content, electric fields or in the case of MREs, magnetic fields. The MREs are interesting materials especially for the active stiffness and vibration control of structural systems. As a controllable stiffness element, MREs can offer innovative engineering solutions to various engineering challenges. Recently, they are being considered as new enabling components in active control systems, such as adaptive tuned vibration absorber and improving seismic protection base-isolated structures. The characteristic response will be influenced by many factors including; the elastomer matrix, the size, distribution, composition and percentage volume of the ferromagnetic particles, and whether the ferromagnetic particles are aligned in chains or randomly dispersed. A review is presented in this paper of the characteristic properties of magnetorheological elastomers and how these properties are affected by varying magnetic fields and the indicated compositional parameters. Besides describing the fundamental behavior of MREs, various applications of MREs for seismic protection are discussed and compared.

Magnetorheological Elastomer Performances with the Presence of Carbon Black

This paper deals with the isotropic magnetorheological elastomers (MRE) samples which compounded in the absence of magnetic field. Two types of MRE composites with and without the addition of carbon black were fabricated. The mechanical properties through tensile test were obtained by using an Instron Tensile Machine. Morphological characterization test of these MRE samples was conducted by using a scanning electron microscopic (SEM). From the experimental study, it can be concluded that, the addition of carbon black in MRE increases tensile strength, decreases the elongation of the break and also cure time. Thus, this study demonstrated that carbon black has a significant improvement on the mechanical properties of MRE. This method of fabrication of MRE is useful for the further research on rubber bearing application.

Self-healing Shape-Memory Alloy (SMA) in Reinforced Concrete Structures: A Review

The presence of shape-memory alloy (SMA) in civil engineering fields was an eye-opener for researchers to develop better technology which can aid in various related aspects. The superiority of SMA over others is that it has a special capability where it remembers the previous shape and is able to return back to its original shape after being heated. The usage of SMA is tremendous in other applications such as in medical, dentistry, and also in automotive and robotic. However, SMA in structural applications can be considered as new and is still in research mode. Construction fields are always thirsty for new and fresh ideas to make improvements in existing technology. As the construction field has to face the possibility of natural disasters such as landslide, earthquake, and others, technologies are needed to reduce the total damages when such natural disasters occur. The existence of SMA as a new material in construction field gives positive vibes to researchers in creating a new technology. This paper explains the ability of SMA as a self-healing material and its unique properties of shape-memory effect and super-elasticity that are helpful in structural applications. The use of SMAs in reinforced concrete structures has been reviewed to clearly understand its mechanism processes. Comparison between SMAs and regular reinforced concretes were made to distinguish the performance of SMA-reinforced structures. Other recognized issues related to SMA, which is seismic protection of buildings are also presented in this paper.

Energy Dissipation and Strain Recovery of Pseudo-Elastic Shape Memory Alloy Ni-Ti Wire

Shape Memory Alloy (SMA) is classified as a novel functional material characterized by pseudo elastic and shape memory effect and has caught the interest across many research disciplines recently. Owing to its wide properties, originated from reversible austenite to martensite phase transformation, this alloy has been used widely in many applications from medical, aerospace and civil applications. The discoveries of SMAs to be exploited as intelligent materials have become the sparked research to be addressed for their prospective use as seismic resistant design and retrofit. Highlighting the unique properties of pseudo-elastic wire, it is not only have the ability to reverse macroscopically inelastic deformation during earthquake by stress removal to recover their original shape but also have significant promises to dissipate energy, large elastic strain capacity, hysteretic damping, excellent high, low-cycle fatigue resistance, re-centering capabilities and excellent corrosion resistance. Hence, this study evaluates the cyclic properties of pseudo elastic Ni–Ti shape memory alloys to assess their potential for seismic applications. An attempt is devoted to correlate the influence of annealing temperatures to the hysteretic behavior of Ni-Ti alloys in terms of fatigue resistant in cyclic loading, mechanical properties at ambient temperature, loading history, equivalent damping, energy dissipation and recovery stress were investigated experimentally. The sample of Ni-Ti wire of 0.127 mm diameter of as received wire had a nickel to titanium ratio of 0.49:0.51 and were heat treated to produce pseudo-elastic response at room temperature. Based on the experimental findings, the pseudo-elastic properties of as received wires have found to be in a good agreement in terms of their ability to dissipate energy through repeated cycling without significant degradation or permanent deformation and better response for seismic application to be optimized. The tensile cyclic test obtained demonstrated a rounded loading curve based on a 0.2 % offset. The as-treated has improved the energy dissipation, but has reduced in pseudo-elasticity. This is due to the formation of martensitic phase upon heating. It is evident from the XRD results, the presence of both austenite and martensite at room temperature. The improvement in energy absorption could be resulted from the greater enthalphy for the phase transition. This is due to pseudo elastic is highly sensitive to the temperature. Extreme temperature can completely eliminate the superelastic effect due to the formation of martensite and unwanted secondary phases such as Ni4Ti3 and and Ti2Ni. The experimental results show potential for the use of SMAs in seismic applications and provide areas for continued research.

Seismic Site Classification of JKR Bridge at Sungai Sepang Using Multichannel Analysis of Surface Wave (MASW)

In seismic engineering, the dynamic property of the soil is one of the most important aspects in ground response analysis. Dynamic property is significantly affected by local soil deposits. Shear wave velocity (V s) of soil is one of the main parameters in determining the amplification factor on ground surface. This study aims to determine the shear wave velocity profile of the bridge at Sungai Sepang by using multichannel analysis of surface wave (MASW) method. All the acquired raw data from the MASW field test were analyzed and it can be summarized to three major steps: First, filter the wiggle plot to the analyzable range of frequency of Rayleigh wave; second, develop the dispersion curves of Rayleigh wave phase velocity and; third, inversion of dispersion curve to obtain the V s profiles. The filter and the development of dispersion curve processes were carried out by using Pickwin softwis (SeisImager/SW). Results show that the soil for bridge at Sungai Sepang is having a very low V s30, which is 143.3 and 137.2 m/s, respectively. The soils are classified as Class E which can be considered soft soil according to Uniform Building Code (UBC). Based on the N-SPT value by using empirical formula, the value of V s30 ranges from 101.22 to 151.87 m/s by using different empirical formula. It can be concluded that the value of V s30 for bridge by using MASW is accepted since the value is near to the value of numerical equation from N-SPT value based on borehole data at Sungai Sepang site.

Performance of Carbon Nanotubes (CNT) Based Natural Rubber Composites: A Review

Carbon nanotubes (CNTs) are hollow cylinders of molecular-scale tubes of graphitic carbon with outstanding properties. They are possessed high strength, high stiffness and good electrical conductivity depending on their structure and diameter. This review outlines the performance of carbon nanotubes based on results of the author’s research, essentially composites and describes the properties of carbon nanotube elastomeric composites. The Functionalization of CNTs and the applications of these materials are also discussed. The capability of carbon nanotubes to impart the conductivity to insulating elastomeric matrices has been clearly shown. Most markedly, this work has illustrated the performance encountered with the properties of CNT based Natural Rubber.

Shear capacity of profiled web girders with intermediate rolled-in stiffeners

A girder whose web is profiled can lead to a structural system of high strength-to-weight ratio. In 1960s, the usage of a flat web girder had been replaced with profiled web since this profiled web can increase stability against buckling. The usage of girders with profiled webs has become progressively popular as these girders can reduce self-weight of the structure and increase structural efficiency. Use of profiled configuration in the web provides uniformly distributed stiffening in the transverse direction of the girder. In this study, an innovative idea is introduced to improve the efficiency of the web through intermediate rolled-in stiffeners. The shear capacities of a series of profiled web girders with intermediate rolled-in stiffeners have been numerically studied using a commercially available finite element software LUSAS. The numerical study includes the development non-linearities of material and geometry of finite element models, whose results are compared with previous experimental results. The entire plate components such as flanges, web and rolled-in stiffeners were modelled using eight-noded quadrilateral thin shell elements. Each specimen was tested under a shear load placed on the top flange. The shear capacities of different configurations profiled webs with intermediate rolled-in stiffeners are discovered. Generally, whenever rolled-in stiffeners are introduced within the profiled web, the web is able to cater more loads.