Applied Mechanics and Materials Vol. 842

Abstract: Laser cutting is a process used as an alternative of conventional machinery that works by directing the output of the laser power on the would be-cut material. Material exposed to the laser light is then melted, burned, and evaporated by the gas. Thus, this laser cutting process produces high-quality edge surface. The research aimed to determine the effects of the laser head distance and cutting speed to obtain minimum width of gap and the laser cutting process with the 3 mm-thick polymethyl methacrylate. This experiment used a 60 Watt-powered laser cutting machine to take the specimen in the form of a 30 mm-long horizontal line. The laser head distance ranged from 6 to 10 mm and cutting speed varied from 4 to 8 mm/s. A stereo zoom microscope with 30 times magnification was used to measure the gap. The research resulted in 0.582 to 0.931 mm as the value of the width gap in the cutting of 3 mm thick 60 Watts-powered polymethyl methacrylate (PMMA). The laser head distance and cutting speed contributed to the gap width of the product. The increased cutting speed and gap distance resulted in the smaller gap width.

Abstract: The influence of fiber size on mechanical and water absorption properties of recycled Polypropylene/Palm Empty Fruit Bunch (namely, rPP/EFB) bio-composites has been conducted study. rPP/EFB bio-composite was a compounding of recycled polypropylene (rPP) and palm empty fruit bunch (EFB) with different sizes, i.e. particle size (150 mesh sieve escaped, referred as p-EFB) and short fiber (s-EFB). Manufacturing of the bio-composites was prepared by the solution method in boiling xylene via reactively process using benzoyl peroxide as an initiator. The addition of coupling agent, such as maleic anhydride grafted polypropylene (PP-g-MAH) was improve the chemical interaction between the rPP and EFB which evidenced by the shift of the wave number of raw materials on infra-red spectra of rPP/EFB bio-composite. Mechanical properties test showed that s-EFB was increase the tensile strength value up to 95% compare to rPP, higher than the p-EFB which is 56% compare to rPP. However, the elongation percentage of the bio-composites contain s-EFB was lower than the bio-composites contain p-EFB. Water absorption analysis also performed in this study to determine the biodegradability of bio-composites. In this study, fiber size gives a considerable influence on the mechanical properties of rPP/EFB bio-composites, however not significant on water absorption properties.

Abstract: Manufacturing industries have consumed 30% of the total world energy. The main energy source used in those manufacturing industries is the electricity generated from fossil fuels such as oil, gas, and coal as a result in causing the environmental and economic issues. This paper presents an experimental study in order to get the minimum energy consumption during turning of aluminum 6010 with the conventional machine tool under dry cutting condition by optimizing the cutting parameters to contribute to those issues. An analysis of variance (ANOVA) was employed to analyze the effects and contribution of depth of cut, feed, and cutting speed on the response variable, specific cutting energy. The result of this experiment showed that the feed was the most significant factor for minimizing energy consumption followed by the cutting speed and the depth of cut. The minimum energy consumption was obtained when the highest level of cutting parameters have been used.

Abstract: This paper aimed to develop a methodology for assessing environmental friendliness of turning processes from energy consumption’s perspective. This methodology was limited on the process level study, which turning process was chosen as the assessed process. Recently, the green manufacturing has become a very important matter due to environmental impacts caused by manufacturing processes. Reducing the amounts of input energy or increasing efficiencies of production equipment’s can help to achieve the green manufacturing level, but it does not indicate the level of energy consumption. Therefore, a methodology is needed to determine how green a manufacturing process on energy consumption’s perspective. In this case, an energy indicator can be used to evaluate the energy usage performance. Based on the experimental data from several different machines, regression lines is constructed (using data envelopment analysis) as the efficiency reference values. According to the position of the energy efficiency from the assessed process to the efficiency reference values, it will determine whether the process has a high or low efficiency (as the assessment result). This methodology has tried to indicate the level of energy consumption, by comparing the result from energy indicator with the reference value. Energy indicator for material removing processes is commonly used to predict the total energy consumption for energy assessment without comparing the result to the reference value.

Abstract: Red cabbage extract has been investigated in this work whether it would perform as a green corrosion inhibitor for API 5L grade X60 steel in 3.5% NaCl environment. Based on the FTIR and LC-MS analysis the active compounds of corrosion inibitor were hydroxyl, carbonyl and cyanidin. The Tafel polarization test results showed that red cabbage extract performed as a mixed corrosion inhibitor and the Electrochemical Impedance Spectroscopy test results showed that the impedance, polarization resistance and capacitive resistance of steel surface increased with the addition of red cabbage corrosion inhibitor. Based on evaluation of the testing results red extract red cabbage performed significant corrosion inhibition effect. The inhibitor efficiency increases with increased corrosion inhibitor concentration and the optimum inhibitor percent efficiency achieved 81%. The adsorption mechanism of red cabbage corrosion inhibitor can be considered as a Langmuir Isotherm

Abstract: Reliable experimental data on compressive strength of composite material are important, especially for designing structures having dominant compressive stresses, such as bolted joints. Composite materials usually have lower compressive strengths compared to tensile strengths. Woven composites added more complications. Initial waviness in woven composites makes the compressive strengths even much lower. Therefore, in this paper, experimental study on the compressive strengths of woven composites will be presented. The experiments used standard ASTM D3410M-03. Woven glass-epoxy will be tested extensively. The specimens were produced using standard hand layup techniques. Several layup configurations were tested, namely (0/90)_s, (0/90/±45)_s and (±45)_s. The results showed that woven glass-epoxy generated failure modes specifically found in compressive tests of composites, such as: fiber micro-buckling, fiber crushing and shear band-formation. It was also found that unlike in the case of tensile tests, the layup configurations did not affect the compressive strength values. It seems that the fiber orientation will not affect significantly the compressive strengths. The epoxy matrix played more dominant role on the compressive behavior of woven glass-epoxy composites.

Abstract: In automotive parts market, there are two classes of commercial brake pad that are original equipment manufacturer (OEM) and aftermarket (Non-OEM spare part). In manufacturing of commercial brake pad materials, the difference of ingredient or concentration used is important because of differences in characteristics and cost. It is well known that the OEM brake pads are more expensive than the Non-OEM brake pads. In this study, the OEM and the Non-OEM of passenger car brake pad were evaluated in order to obtain a comparison of friction characteristics, composition, and microstructure between them. The OEM and the Non-OEM brake pad were purchased, cut out to form specimen, and then evaluated to obtain material characteristics. Specimens were subjected to friction testing using pin on disc machine and microstructure examinations. The results show that the OEM brake pad material has lower and more stable in coefficient of friction than the Non-OEM brake pad material. The OEM brake pad material also has more wear resistance than the Non-OEM brake pad material. Examinations using SEM/EDS show that the OEM brake pad material contains metallic fillers that are Cu and Fe, on the other hand, the Non-OEM brake pad material does not contain metallic filler. The Non-OEM brake pad material uses asbestos as reinforcement.

Abstract: Vickers microindentation hardness test has been applied for a long time to determine the mechanical properties of a small volume of samples. The procedure of this hardness test consists of using a constant load on a rigid indenter and measuring the dimensions of the indenter residual impression (indentation imprint) on the surface of the sample tested after loading and unloading. The objective of this research is to characterize the mechanical properties and material constants of HQ (High Quality) 705 alloy steel mainly its VHN (Vickers Hardness Number) and tensile strength before and after quenching and tempering heat treatments. The characterization is based on Vickers microhardness dependence load curves.Quenching treatment was performed in a furnace by heating the samples at austenite temperature of 850 ^o C with holding time of two hours and then the samples were rapidly cooled in oil bath. Tempering processes were conducted by heating again the quenching samples to temperatures of 150, 200, 250, 300, 350, 400, 450, 500, 550 and 600 ^o C with holding time of two hours for each sample. Finally, all samples were slowly cooled in atmospheric temperature. The mechanical properties of samples were characterized by using Vickers microhardness dependence load curves.The results show that VHN (Vickers Hardness Number) depends on indentation load and VHN increases with increment of load for indentation load lower than 5 N. VHN is almost constant for indentation load greater than 5 N. The raw material (without heat treatment) has the VHN and tensile strength of 3413 MPa and 1050.61 MPa respectively and the quenched samples have the VHN and tensile strength of 5407 and 1861 MPa respectively. The Vickers hardness and tensile strength decrease with the increment of tempering temperatures. The higher tempering temperature produces lower hardness and tensile strength. The raw material tensile strength of 1058.8 MPa obtained by tensile test is comparable to its tensile strength of 1050.61 MPa obtained by Vickers indentation. This result indicates that Vickers microindentation is valid to use for evaluating the tensile strength of HQ 705 alloy steel.

Abstract: Stresses were calculated for orthotropic laminate plate loaded by a frictionless pin in a circular hole of the same diameter. These calculations were based on finite-element analysis for five laminates; 0⁰, [±45⁰]_s, [0⁰/90⁰]_s,[0⁰/±45⁰]_s, and quasi-isotropic [0⁰/±45⁰/90⁰]_s. stress distribution, based on nominal bearing stress, were determined for wide ranges of the ratios of width to diameter and edge distance to diameter. Orthotropic had a significant influence on both the magnitude and location of the maximum tensile stress concentration on the boundary of the hole. The laminates with 0⁰ plies developed the peak tensile stress near the ends of the pin-hole contact arc. But the ±45⁰ laminates had peaks where ply fiber were tangent to the hole. The finite width and edge distances strongly influenced the tensile stress concentration. In contrast, the finite widths and edge distances had little effect on bearing stress concentration. For the practical range w/d = 2, the peak tensile stresses were as much as 50 percent larger than the infinite-laminate value. For e/d=1, these stresses were greater 60 percent than infinite-laminate value. In contrast, the finite width and edge distance had little effect on bearing stress concentrations.

Abstract: The aim of this research is to investigate the alkali treatment influence on tensile strength physical and mechanical properties of agel leaf fibers (ALF). The presence of surface impurities and the large amount of hydroxyl groups make plant fibers less attractive for polymeric materials reinforcement. ALF were subjected to alkali treatments with 2 and 4% NaOH solutions for different soaking times of 1, 12, and 24 hours at room temperature. The tensile test of single fiber was done according to ASTM D3379-75 standard. The chemical changes and the fiber surface after alkali treatment were investigated by using Fourier transform-infrared (FTIR) and scanning electron microscopy (SEM), respectively. Tensile tests showed the alkali treatment of ALF results in different tensile strength compared to untreated ALF. The highest tensile strength (1464 MPa) is found for ALF immersed in 4% NaOH for 1 hour. FTIR showed that the hemicellulose and lignin components in the ALF are removed by NaOH treatment. SEM observation of the treated ALF showed the removal of impurities and the increase of roughness on the ALF surface with alkalization. These results show that alkali treatment can increase the tensile strength of ALF.