Applied Mechanics and Materials Vol. 735

Abstract: The graft copolymerization was carried out under nitrogen atmosphere using the free radical initiation technique. The blend formulations were first dry blended using a mixer before being milled into sheets on a two-roll mill at 170°C, and then hot pressed into composites specimens at 175°C for 10 min. The objective of this study to investigate the mechanical and thermal properties of PVC blends. The flexural strength and modulus of ungrafted composites increased with increasing filler content from 2 to 10 part per hundred resin (phr) while the grafted composites also increased only from 2 to 6 phr filler content. The flexural modulus of ungrafted was higher compared to the grafted composites whereas the grafted showed good flexural strength than ungrafted composites. The impact strength of both composites decreased with increasing filler content but the ungrafted composites showed good toughness than grafted composites. The thermal stability of both composites increased compared to unfilled PVC.

Abstract: The objective of this study is to investigate the effect of halloysite nanotubes (HNTs) loading on mechanical and thermal properties of poly(ethylene terephthalate)/polycarbonate (PET/PC) nanocomposites. Nanocomposites containing 70PET/30PC and 2-8 phr HNTs were prepared by twin screw extruder followed by injection moulding. As the percentage of HNTs increased, the flexural modulus increased. However, the flexural strength decreased with increasing HNTs content. The impact strength also decreased when HNTs increased. Thermogravimetry analysis of PET/PC/HNTs nanocomposites showed higher thermal stability at high HNTs content. However, on further addition of HNTs up to 8 phr, thermal stability of the nanocomposites decreased due to the poor dispersion of HNTs.

Abstract: Development of epoxy with filled particles provides an avenue for manufacturing applications in the tooling industries especially in the mould and die industries. The performance of epoxy and fillers as mould materials is greatly dependant on the production quantity and process conditions. Metal and non-metal fillers such as copper, brass, graphite and silicon carbide are blended into the epoxy matrix, altering the mechanical properties, as well as thermal conductivity of the epoxy composite. This review presents the investigation on the effect of varying composition of metal and non-metal fillers on the mechanical properties of epoxy composite. Different mixing ratios are investigated ranging from 10%, 20%, 30% and 40%, based on the weight ratio of epoxy resin, hardener and filler material. Previous studies showed that increase in amount of filler increases the hardness and compression strength of epoxy matrix. Adversely, tensile strength shows a detrimental effect with the presence of fillers, whereby increase in metal fillers reduces the tensile strength with increased composition loading from 10% to 40% of weight. Wear rate was found to reduce with the presence of aluminum, alumina and silicon carbide, hence increasing the wear resistance of the epoxy composite.

Abstract: Stainless steel, titanium alloys and cobalt chromium molybdenum alloys are classified under the metallic biomaterials whereby various surgical implants, prosthesis and medical devices are manufactured to replace missing body parts which may be lost through accident, trauma, disease, or congenital conditions. Among these materials, cobalt chromium molybdenum alloys are the common cobalt base alloy used for orthopedic implants due their excellence properties which include high corrosion resistance, high strength, high hardness, high creep resistance, biocompatibility and greater wear resistance. This paper summarises the various aspects and characteristic of metallic biomaterials such as stainless steel, titanium and cobalt chromium alloys for medical applications especially for orthopedic implant. These include material properties, biocompatibility, advantages and limitations for medical implants applications.

Abstract: Kenaf natural fibre has become the subject of interest for a wide range of engineering sectors due to its biodegradable and outstanding mechanical properties. In this study, the effect of loading rate on the indentation behaviour of fibre metal laminates (FMLs) based on kenaf/epoxy subjected to static indentation loading was investigated. The fibre metal laminates were made of chopped strand mat (CSM) kenaf fibre with epoxy resin composite and 0.6 mm thickness of 1100-O aluminium alloy sheet by using vacuum infusion process (VIP) and hydraulic pressing technique. The experiments were conducted by using a universal testing machine with loading rate of 1 mm/min, 10 mm/min and 100 mm/min. The results of indentation resistance, energy absorption and corresponding indentation failure mechanisms were compared and discussed in this study. For 2/1 FMLs, the maximum contact force increased when the loading rate increased. The loading rate did not affect the indentation failure mechanisms of the 2/1 FMLs. However, for 3/2 FMLs, delamination occurred when the specimens were indented with loading rate of 10 mm/min.

Abstract: Hydraulic Fracturing, Proppant, Acid FracturingAbstract. Increase in the price of oil and gas during recent years have motivated oil and gas companies to focus on the methods that lead to increasing in the oil and gas production. Oil well stimulation as one of these methods includes a variety of operations that performed to improve productivity of the well. The main objective of a stimulation treatment is to increase the rate at which the formation delivers hydrocarbons naturally. Today’s well stimulation method is converted to the appropriate method in the oil and gas industry to maintain or increase of well productivity. Injection of acid to partially dissolve the rock, and hydraulic fracturing to split the rock and prop it open with proppant are two common techniques for stimulating of the wells. Deciding about selection of the best method for stimulation of the wells is related to the comprehensive evaluation of capabilities of each technique and conditions which are governed on specific job intended. In this article, we are trying to present a description about well stimulation method, methods that are employed to execute well stimulation, and application of these different techniques for stimulating of wells.

Abstract: The abundant fraction of agricultural waste materials in the environment that poses disposal challenge could be converted into useful value added products such as activated carbon. Palm oil shell based carbon was prepared by two step process using K₂CO₃ as the chemical activant. The Langmuir surface area, BET surface area and pore volume were 817 m²/g, 707m²/g and 0.31cm³/g. From the FTIR analysis, carbonyls, alkenes and hydroxyls were identified. The SEM image shows gradual formation of pores due to elimination of volatiles and contaminants. Carbonization at 800°C for 2 hours and activation at same temperature for 1h has the highest yield of 23.27%. The proximate and ultimate analysis shows high percentage of carbon and low percentage of ash which is an indication of a good material for production of porous carbon. The activated carbon produced showed basic properties suitable for removal of organic contaminants in aqueous solutions. However, the aim of this study is to produce a green and porous carbon with controlled pores and surface properties for organic contaminants removal from water and wastewater.

Abstract: In this study, a knowledge-based system has been developed for selection of non-conventional machining processes using a hybrid multi-criteria decision making Method. This approach is a combination of DEMATEL (Decision Making Trial and Evaluation Laboratory), ANP (Analytic Network Process) and VIKOR (VlseKriterijumska Optimizacija I Kompromisno Resenje, in Serbian, meaning Multi-criteria Optimization and Compromise Solution) methods which evaluates different types of quantitative and qualitative measures of performance and economic factors, and ultimately provides a set of capable processes in order of priority. Twelve machining processes, eight group of workpiece material and eighteen shape features have been investigated in this study. What separates this approach from others is that, this hybrid method considers the influence of factors in the network relation map as well as their relative importance. Moreover, unlike other popular ranking methods such as TOPSIS (Technique for Order Preference by Similarity to the Ideal Solution), it is not just based on two reference points, namely ideal and inferior points; instead, it proposes a compromise solution and not just a single ranking score. Observations have shown that the developed system works satisfactorily, yields acceptable results and makes accurate decisions as well. It also provides a comparative study among the alternative processes by utilizing graphical features for better analysis and judgment of acceptable alternatives.

Abstract: In this paper design and analysis a die meant to cone explosive forming have been investigated. Since the explosive forming dies are subjected to blast loading, failure is too likely to pass. Likewise, the special geometry such as existing the several holes, sealing grooves, vacuum channel and fillets of this type of dies under explosion wave makes their analysis complicated. In the present work, the die was designed according to the final product dimension assisting a design software. In the next step the die under blast loading was analyzed using finite element method utilizing FEM software. The outcomes exhibit that the die is capable to withstand the explosion load. Besides, the trend of this paper is recommended as a routine for the designers who are going to design these types of dies.