Showing papers in "Advanced Materials Research in 2020"

Evaluation of Steel Corrosion in Concrete Structures Using Impact-Echo Method

Abstract: The impact-echo method is commonly used for detection of flaws in concrete elements based on the shift in the thickness frequency of a plate-like member. However, there is a need to develop this efficient technique for other applications. This paper investigates the feasibility of using the impact echo-method for identifying corrosion of steel reinforcement in concrete structures. For this purpose, 180 reinforced concrete cubes were cast and tested. The main parameters studied were the amount of recycled aggregate (i.e. 0%, 25%, 50% and 100%), nanosilica (1.5% and 3%) and the steel bar diameter (12 and 20mm). Different levels of corrosion were electrochemically induced by applying impressed voltage technique for 2, 5, 10 and 15 days. The impact-echo results were correlated against the actual corrosion levels obtained by the mass loss method. The experimental results showed that the response of impact echo in terms of frequency peaks is found to be sensitive to the high and moderate levels of corrosion. However, no clear trend was observed at the initial stage of corrosion. It is demonstrated that the impact-echo testing can be effectively used to qualitatively detect the damage caused by corrosion phenomenon in reinforced concrete structures.

Tungsten Inert Gas (TIG) Cladding of TiC-Fe Metal Matrix Composite Coating on AISI 1020 Steel Substrate

Abstract: TiC – Fe composite coating was produced on AISI 1020 steel by the tungsten inert gas (TIG) cladding process to increase the hardness and wear resistance properties of the substrate. In this paper authors have investigated the effect of process parameters on the microstructure and hardness value of the coated layer. In this TIG cladding process the variable parameter is only current, whereas the other parameters such as scanning speed, standoff distance, and voltage and gas flow rate are fixed. Fe and TiC powders were mixed in the proper ratio of 80wt% - 20wt% and 90wt% - 10wt% respectively. The microstructure and micro-hardness value of the samples were investigated by the scanning electron microscope (SEM) and Vickers micro hardness tester. The result of SEM shows the distribution of the coating powder in the cladded zone. Micro hardness profile shows the variation of the hardness value in the cladded zone as well as in the substrate. The hardness value decreases with increase in distance from top surface of the cladded layer, which is due to difference in cooling rate. Also, the hardness value of cladded layer decreases with increase in current from 140A to 150A. The maximum hardness value of cladded layer was achieved as 262 HV0.05 with 140A current and composition of 90 wt.% - 10wt% (Fe - TiC), which was nearly two times higher than that of the as received AISI 1020 steel substrate. Keywords TIG, Microstructure, Micro hardness, Titanium Carbide (TiC), Iron (Fe) powder.

Effect on Shear Strength and Hardness Properties of Tin Based Solder Alloy, Sn-50Bi, Sn-50Bi+2%TiO2 Nanoparticles

Abstract: Solder alloys are important joining medium widely used in the electronics industry to connect components to printed circuit board PCB. The Sn-Pb solder alloys have been the cornerstone medium used for a long time. Unfortunately, the use of Pb was banned by the European Union due to the harmful environmental and health issues with Pb. Therefore, in this study, the Sn-50Bi and Sn-50Bi+2%TiO2 nanoparticles lead-free solder alloy is investigated based on their shear strength, Vickers hardness, and melting temperature. The investigation shows that the hypo eutectic Sn-50Bi has a low melting temperature of approximately 145°C, and the 2%TiO2 nanoparticles reinforced Sn-50Bi has a melting temperature of around 182°C, which is lower than the traditional Sn-Pb (Tm=183 °C) and Sn-Ag-Cu (Tm=227°C). Furthermore, the developed Sn-50Bi had a Vickers hardness and shear strength of 26.81 HV and 40.78 MPa respectively, higher than the other leaded and lead-free solders. However, after the reinforcement, the hardness increased by 12% (30 HV) and a slight increase of 2.5% (42.4MPa) in shear strength. Overall, the addition of the TiO2 nanoparticles showed a clear influence on the Sn-Bi properties. The results obtained from this study seem satisfactory to the electronic industry and the environment.

Study of Surface Roughness and MRR in Turning of SiC Reinforced Al Alloy Composite Using Taguchi Design Method, ANN and PCA Approach under MQL Cutting Condition

Abstract: This paper emphases on the effect of various machining constraint on surface roughness and material removal rate in turning SiC reinforced Al alloy composite through taguchi orthogonal array based experimental analysis which has been further optimized using principal component analysis (PCA). Experimental investigation has been conducted under minimum quality lubricant (MQL) cutting environment. Palm oil has been used as lubricant where flow rate and pressure were kept at 120 ml/hr and 8 bar. The whole experiment has been designed using L25 orthogonal array having three input parameters and five different level to measure surface roughness and material removal rate. Taguchi S/N ratio-based optimization has been implemented where smaller the better criteria has been used for surface roughness whereas larger the better criteria has been used for material removal rate. From Analysis of variance, it is observed that cutting speed and feed rate are the most prominent factor for surface roughness. Nevertheless, Depth of cut and cutting speed are the most dominant factor for material removal rate. While comparing the predicted output values with experimental values, MAPE value is found in the range of 0.23 % for surface roughness and 0.045 % for material removal rate which is in very much tolerable range. Correlation coefficient value for experimental values of the resultant output is 0.98286 and 0.99869 respectively which signifies the effectiveness of the whole experiment. Subsequently, machining parameters were optimized using PCA technique. To attain satisfactory response values, depth of cut, cutting speed and feed rate need to be at 0.85 mm, 396 m/min and 0.16 mm/rev respectively. By applying the model, surface roughness of 0.7257 μm and MRR of 53856 mm3/min can be obtained. Keywords: SiC reinforced Al alloy; Turing; Minimum Quality Lubricant; Surface Roughness; MRR; Taguchi orthogonal array; Principal component analysis

Investigations on the Doping Effects on the Properties of Piezoelectric Ceramics

Abstract: In the present paper (1-x)Pb (Zr1-yTiy)O3 – xPb (Mn1/3Sb2/3)O3 – z at%E system, with E = Pr3+, Nd5+ and Gd3+ where x = 0.12; y = 0.48; z = 0 and 0.02 ceramic synthesized by solid state reaction technique is analysed. The investigation aims studying of the effect of dopants on the dielectric and piezoelectric properties of such piezoelectric ceramic. The prepared powders have been uniaxially pressed into discs with diameter of 10 – 12 mm and thickness of 1.2 mm. Sintering has been carried out in air atmosphere at temperatures of 1150°C and 1200°C, respectively, for 2 hours each, followed by a controlled cooling at a rate of 200°C /h. The piezoelectric properties have been investigated after a suitable preparation, including polishing, metallization. The structure of the samples has been determined by X-ray diffractometry (XRD), while the morphology and grains size have been investigated by the scanning electron microscopy (SEM). The piezoelectric properties have been studied by the resonance - antiresonance method. XRD analysis reveals a perovskite tetragonal structure and, as expected for ceramic materials, SEM analysis indicates that the average grain size increases as sintering temperature increases. The dielectric and piezoelectric properties have been determined measuring the ceramic discs, and properties, as dielectric permittivity (εr), dielectric loss (tg δ), and the electromechanical coupling factor (kp) have been obtained. The acquired results indicate a significant effect of the dopants on the dielectric and piezoelectric properties of such materials.

Synthesis of SnO2 Nanoparticles Using Ficus religiosa Leaf Extract and their Application in Fabrication of OFETs for Glucose Monitoring

Abstract: Organic field effect transistors (OFETs) as a sensor have gained interest of researchers due to its portable size and less expensive design in the field of medical diagnostic, food monitoring, chemical detection, wearable sensors, etc. In this present research work, we demonstrate the fabrication of OFETs from organic-inorganic SnO2 nanoparticles tailored pentacenefor glucose detection. SnO2 nanoparticles were synthesized bygreen method using Ficus religiosa leaf extract. The as-synthesized SnO2 NPs with cassiterite crystal structure was analysed using X-Ray Diffraction (XRD) and the energy bandgap of ~3.8 eV was calculated using Tauc relation with absorption spectra so obtained from UV-vis spectroscopy (UV-vis). The structure and morphological analysis of SnO2 NPs with size of ~15 nm was confirmed by Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM) analysis. The sensor characteristics of OFET device fabricated using pentacene layer (soluble pentacene precursor of DMP) and as-synthesized SnO2 nanoparticles confirmed the aqueous glucose (glucose in water) detection at room temperature (27 °C). The extracted electrical parameters such as mobility (μ), On-current (Ion), saturation current (IDsat) and the sensor response were discussed to support the sensor characteristics.

Evaluation of the Effect of Cooling Conditions and Heat Transfer Coefficients on Solidification of Al-Cu Binary Alloy in Static Casting Process

Abstract: Source-based method for modelling solidification problems have been modified and presented in the current work. It coupled the effect of thermal radiation to macro-transport codes and was solved using finite volume method. The problem was formulated based on the classic continuum energy conservation equation for transient conduction controlled solidification system. Radiation heat transfer and latent heat evolution were added as source terms and solved with appropriate numerical treatments to obtain a system of linearized source terms. This circumvented the need for the application of any analytical solution to the intricate heat transfer regimes included in the model. The effect of cooling was carried out under various cooling conditions imposed on different surfaces of the mould for the solidifying metal. The resultant influence of cooling on the solid fraction evolution during static casting was then evaluated. The simulated cooling curves show that thermal radiation have no influence on the rate of heat extraction and the results show that the predicted cooling curves and solid fraction updates are similar to the results of previous models. The predicted curves at the top section of the open mould however show a little deviation due to effect of surface tension gradient forces. It was further revealed that heat transfer coefficients has more effect cooling curves and temperature contours at the lateral mould surfaces than the interior of the casting which is in agreement with theory of Newtonian cooling.

Integrity and Life Assessment of Welded Joints Made of Micro-Alloyed High Strength Steels

Abstract: Structural integrity and life of welded joints made of a micro-alloyed low-carbon fine-grained normalised high strength pressure vessel steel, P460NL1 is presented [1]. The researach performed within the scope of this topic involved a large number of experiments, including tensile and bending tests, hardness and toughness, as well as metallography and fractography tests, in order to determine the mechanical properties of the materials and the welded joints in detail, along with their microstructures and their influence on the obtained test results. Specimens cut out of a welded plate with dimensions of 500x500x14 mm were used for the experiments, whereas certain tests required the making of notches in the specimens, inside the heat affected zone, and this welded joint region was the focus of the research. Fatigue experimental tests were based on the assumption that fatigue crack growth rate changes depending on the regions through which the crack passed during its propagation. For this purpose, specimens used in toughness and fatigue tests were divided into four groups, depending on the part of the plate from which they were taken. Numerical calculations were performed using the extended finite element method (XFEM) [2]. Simulations were based on the experimentally determined values of Paris law coefficients, C i m [3-5], for every region through which the crack propagated during each test. Obtained results have indicated good agreement with the experimental ones, which verified the application of extended finite element method in this case.

Researches on Manufacturing Deo Roll Balls by Infrared Radiation Welding

Abstract: The paper proposes the analysis of an alternative technology for manufacturing deodorant roll-on balls of polypropylene. With the current extrusion-blowing technology, the manufacturing of these balls results in an uneven wall thicknesses and a large technological runner of material that needs to be grinded and reintroduced into the injection equipment, which involves additional raw material and energy consumption.The proposed alternate method of manufacturing these balls (as spherical objects) is to form the ball from two ball halves joined together by infrared radiation welding. This process will result in significant savings in raw materials and energy.Further improvements of dimensional capabilities and control of welding parameters are required prior the transfer on high productivity manufacturing lines. Additionally, this technology can be assimilated into other applications where hollow balls of plastic are used.

Mechanical Properties of Duplex Treated Steels Obtained by Instrumented Indentation

Abstract: Nowadays there is a growing need to reduce or control wear, corrosion and fatigue in order to extend the lifetime of mechanical parts, to make engines and devices more efficient, to develop new advanced products, to conserve material resources, to save energy and to improve the safety. The surface properties of mechanical parts may be improved through Duplex treatments. A Duplex treatment is a sequence of two treatments, combining their advantages and leading to better surface properties. A Duplex treatment consisting in nitriding and work hardening through shot peening has been chosen as a solution for improving the properties of EN 34CrNiMo6 alloyed steel. This paper reports the results obtained for hardness and bulk modulus on treated and untreated samples. The samples were examined using a Dynamic Ultra Micro Hardness (DUH) tester under a set of maximum loads ranging from 100 to 1000 mN. Each sample was subjected to load-unload cycle under the same amount of maximum load and the loads vs. penetration depth curves were plotted. Results showed a better mechanical behavior of Duplex treated.

Considerations on the Ultimate Tensile Strength of Butt Welds of the EN AW 5754 Aluminium Alloy, Made by Friction Stir Welding (FSW)

Abstract: Experiments have been performed for the butt welding of 160 mm x 90 mm x 2 mm sheets of EN AW 5754 aluminium alloy, where the friction stir welding (FSW) has been used.Referring to the parent metal, the chemical composition and the form of wrought products of the aluminium alloy EN AW 5754 is presented, according to the standard EN 573-1:2005, respectively EN 573-3:2013. The mechanical properties of EN AW-5754 (Al Mg3) sheets are presented, according to EN 485-2:2016. The experiments have been conducted on the own equipment for friction stir welding, type FSW-4kW-10kN, to execute 8 (eight) FSW test pieces, according to EN ISO 25239-4. A quenched FSW tool, own-made of C 45 grade steel, EN 10083, has been used. The parameters of the FSW tests are shown. As main parameters, the rotational speed of the FSW tool was in the range n = 800 – 1200 rev/min, respectively the travel speed was in the range v = 50 – 200 mm/min. The run of the joining experiments is described and the joining test pieces are presented in figures. The ultimate tensile strength of the parent metal (σmin,pm) is based on the specified minimum tensile strength of the ”O” condition of the parent material, respectively this value is also required for the weld, that is σmin,w = 190 MPa. The specimens T1.0, T1.1, T2.1, T2.2, T3.1, T3.2, T4.1, T4.2, T5.1, T5.2 și T6.1 are adequate and accepted by this tensile test. The specimens T1.2, T6.2, T7.1, T72. and T8.1 can be accepted, if higher properties are achieved with a full postweld treatment. Another possibility is a lower extent of the minimum tensile strength of the weld that shall be in accordance with another design specification, for example σmin,w = 145 MPa. By the correlation of the FSW parameters with the results of the tensile test, the ranges for the main parameters with adequate values of the ultimate tensile strength are established: n = 800 – 1000 rev/min and v = 50 – 100 mm/min. By the conclusions, the main aspects of the execution of the FSW test pieces, as well as the results of the tensile tests are selected. The involved industrial areas of the applications are: electro-technique, electronics, manufacturing, shipbuilding and automotive industries. The FSW process is ecological, because it neither uses, nor produces hazardous substances. The references consist of 12 titles.

Influence of Cooling Time t8/5 on Impact Toughness of P460NL1 Steel Welded Joints

Abstract: The results of impact testing of welded joint specimens taken from a welded plate made of P460NL1 steel are presented in this paper, and analysed with regards to the cooling time t8/5, that was previously calculated. The aim was to determine how the cooling times that were measured, some of which were below the minimum required values, affected the toughness, in terms of total impact energy and its components, crack initiation and crack propagation energy. In addition, this analysis included the effects of temperatures measured at the opposite ends of the plate during the welding process, since this had also affected the cooling times for each welding pass. After observing the differences in total, crack initiation and propagation energy between the tested specimens taken from different parts of the welded plate, it was determined that the specimens from the part where the higher temperatures were measured had shown better, more uniform results, whereas the average total impact energy for specimens from both groups were very similar. It was also noticed that the ratio of crack propagation to crack initiation was more favourable (greater) in the case of specimens from the second group (with higher temperature), as the values of crack initiation energy decreased slightly and the crack propagation energy increased.

Effect of Trap Energy on Series Resistance of Phenosafranine Dye Based Organic Diode in Presence of TiO2 and ZnO Nanoparticles

Abstract: The series resistance (Rs) controls the device performance significantly and for organic diode, the typical value of Rs is quite high. There are not many reports on the investigation of the high value of resistance in organic diodes. In this paper, we report that the trapping of charge carriers which is an important parameter to control the charge transport mechanism in organic solids is responsible for this high value of series resistance. In this paper effect of trap energy on Rs has been studied in the presence of TiO2 and ZnO nanoparticles on Phenosafranine (PSF) dye-based organic diode. It is already reported that by incorporating nanoparticles, trap energy is reduced which in turn increases the conductivity and efficiency of the device. So it is expected that trap energy has a strong influence on Rs. In this work we have measured Rs by using the Cheung Cheung method and the trap energy is also measured by analyzing the dc current. The value of Rs is related to trap energy. The extracted values of Rs are about 250.8 KΩ, 108.0 KΩ, and 98.4 KΩ respectively for only PSF, PSF+ZnO, and PSF+TiO2. It is also been observed that by incorporating nanoparticles the trap energy is reduced. The estimated values of the trap energy are about 0.090eV, 0.078eV ,0.072eV respectively for only PSF, PSF+ZnO, and PSF+TiO2. It has been observed that lowering of trap energy by incorporating TiO2 and ZnO reduces the value of Rs.

A Study on Particle Weight Fraction and Extrusion on the Mechanical Properties and Microstructural Evaluation of Al-Cu/Fly Ash Composite

Abstract: Fly ash is the waste product coming out from thermal power plant is an increasingly urgent problem due to its storage and disposal. At the same time Metal Matrix composites (MMCs) reinforced with ceramic particles such as SiC, Al2O3 and B4C has their partial use in engineering application due to higher cost. The study focuses on the Al-Cu alloy reinforced fly ash particles produced by stir casting followed by hot extrusion. The composites produced by incorporation of fly ash reinforcements by varying 2%, 4%, 6%, 8% and 10wt% is hot extruded with an extrusion temperature of 400°C, extrusion rate of 5mm/s and extrusion ratio of 1.77:1. The extrusion composites have been evaluated based on the investigation of mechanical properties and microstructure. The results showed that, the amount of porosity increased with increasing the percentage of fly ash reinforcements in stir cast and the extruded composites is almost gratis from porosity. Hardness and tensile strength of composites increases with increases in percentage of reinforcement by stir and extruded composites. But extruded composites show better mechanical properties than stir cast composites. Wear test under different loads and for 45 minutes duration have been conducted on both cast and extruded composites. The worn surfaces have been observed under Scanning electron microscope (SEM) to understand the mechanism of wear. Extruded composites possess lower wear rates under all studied loads with constant sliding velocities when compared with cast composites. Microstructural study using SEM shows that the fly ash particulates in the molten matrix forms strong matrix reinforcement interface and their distribution might have led to the increase in mechanical properties of the composites due to fine grain structure during extrusion and dislocation density in the matrix.

Researches on Manufacturing Deo Roll Balls by Ultrasonic Welding

Abstract: Ultrasonic welding is a fast and economical solution for plastic parts. This article proposes Ultrasonic Welding as an alternative technology for manufacturing deodorant roll-on plastic balls. With the current technology, the manufacturing of these balls results in an uneven wall thicknesses and a large technological runner of material that needs to be grinded and reintroduced into the injection equipment.The proposed method of manufacturing these deodorant balls is to form the ball from two ball halves joined together by ultrasonic welding. This process will result in significant savings in raw materials and energy.Further improvements of welding parameters and dimensions are required prior the transfer on high productivity manufacturing lines. This technology can be assimilated into other applications where hollow balls of plastic are used.

Study of α”-Martensitic Transformation in Ti35NbxSn Alloys Subjected to Cryogenic Heat Treatment

Abstract: TiNbSn alloys have been extensively researched due to several properties they exhibit, including high mechanical strength, low elastic modulus, superelasticity, shape memory effect, biocompatibility. The present study evaluated the cryogenic heat treatment in the Ti35NbxSn alloys (x = 0.0; 2.5; 5.0; 7.5). The alloys were arc melted, cold formed and quenched in both water and liquid nitrogen at-198° C. The Ti35Nb2.5Sn alloy was also aged after exposed to both quenching medium. Microstructure and microhardness analyses were performed. Cryogenic treatment was not enough for transformation of primary β phase into martensitic α” in alloys containing 5 and 7.5% Sn. Cryogenic treatment provided β to α” transformation in alloys containing 0 and 2.5% Sn. The Sn-free alloy was more likely to α\" transformation in both quenching medium. The alloys microhardness increased with decrease of both quenching temperature and Sn content. The increase of α\" is also related to the increase of the alloy microhardness after aging.

Mechanical Testing of GFRP Composite Materials Used in Wind Turbine Blades Construction

Abstract: The paper proposes to present the results of the evaluation of glass fiber reinforced plastics (GFRP) used in the construction of wind turbine blades. In a wind turbine, the blades are the most exposed to damages and the defects which appear are various and are connected with the type of manufacture, simple/complex loading, environmental conditions etc. In order to increase the lifetime span and to analyze the degradation phenomena during the materials functioning, destructive evaluation tests are performed to determine the mechanical property, by testing pure shear on specimens Iosipescu, from GFRP with woven reinforcement at [± 45°] and [0°/90°], with the shear fixture, endowment of Technical University Gh.Asachi Iasi.

Mechanized Welding with Metal Cored Wire

Abstract: Currently, there is a steady upward trend in the consumption of flux-cored wires in the global market of welding consumables. One of the rapidly developing technologies for the manufacture of metal structures is shielded gas arc welding with flux-cored wire with a metal core. According to the technology of use, metal cored wires do not differ from solid wires, and even surpass them in some technological characteristics. Taking into account global trends in the development of mechanized welding and the lack of domestic analogues, LLC TM.VELTEK has developed and mastered the manufacturing of high-performance metal cored wire TMB5-MK for welding in mixtures of 82% Ar + 18% CO2, 90% Ar + 10% CO2. The research aimed to study the features of the process of welding with metal cored wire compared to welding with solid wire. It has been established that metal cored wire provides high stability of arc burning in a wide range of welding modes. When welding at the same conditions in the optimal range, the index of stability of arc burning when using solid wire Sv-08G2S is 3 times lower. At the same time, the TMV5-MK wire provides a reduction in spatter losses, an increase in welding productivity and high mechanical properties of the weld metal. It is shown that the stability of the welding process is significantly affected by the electrodynamic properties of the power source and this factor must be taken into account when evaluating the welding and technological properties of welding wires and developing recommendations for their use.

General Considerations Regarding Friction Stir Welding of some Steels Used in Important Industrial Fields

Abstract: The paper present some general aspects regarding results obtained by ISIM Timișoara at FSW of steel alloys, with wide use in important industrial fields. The paper also contains information on own contributions of ISIM Timișoara in the field of FSW.Until the present, ISIM Timisoara has responded to some specific requests from the industry, for applying of the FSW process to light alloys and industrial copper Cu 99.The paper presents some general elements regarding the results obtained to welding steels having wide use in industry and which can substantiate industrial applications.The experimental welding programs were developed using the techniques of application of the FSW process, made by ISIM Timisoara: FSW welding machine, welding tools for steels, monitoring systems of the welding process FSW, respectively system for applying of the FSW-TIG hybrid welding process.Sintered tungsten carbide P20S tools with smooth shoulder and pine in 3 constructive variants: smooth conical, smooth cylindrical and pine with four flat recesses (pyramid trunk) were used.It has been shown that the welding tools made of P20S tungsten carbide, with sharp edges, are more resistant and present the best solution for FSW applications.Experimental programs have shown that by observing specific process conditions, the FSW process can be applied with excellent results when welding steel.

Investigation the Phase Separation in Metallocene Linear Low Density Polyethylene/Polypropylene Blends

Abstract: The present study is aimed at investigated the miscibility in binary blend the Metallocene linear low density polyethylene (PE) and the Polypropylene homo (PP). Metallocene linear low density polyethylene is one of LLDPEs but with lower density higher melt flow index (MFI) than conventional LLDPE. The polyethylene and polypropylene blends (PB) were prepare by using o-xylene as solvent and polyethylene-co-glycidyl methacrylate (PE-co-GMA) as compatibilizer promote blending of immiscible homopolymers and the stability of the blend . The composites were characterized by wide angle X-ray diffraction (WAXD). Long period spacing was obtained using small angle X-ray scattering (SAXS).Crystallinity and melting behavior were studying by use the DSC and TGA, Metallocene linear low density polyethylene provide better behavior than the conventional LLDPE. The tensile test and DMA test were applied on the blends, which displayed improvement on the blend properties by using the PE-co-GMA and confirm the incompatible nature of the blends.

Structural Design of an Auto Panel Die Component Based on the Contact Pressure Using Topology Optimization

Abstract: The main motivation in stamping die industry and academia is panel quality and formability issues rather than the weight and cost of the die. A product should be designed according to the loads that it can be faced in service condition. But somehow this rule is not valid for stamping die design since the minimum distance between the ribs is based on the standards and location and pattern of the ribs which are depending primarily on the company experience. In this work, an auto panel drawing die design is investigated numerically whether it is overdesigned or not. The loads on the die surfaces are calculated by numerical methods. When a panel is drawn between upper and lower die, the contact pressure (CP) occurs on the interface surfaces due to this interaction. Since CP is a vital parameter and it is almost impossible to measure it by experimental methods, it is validated by two different numerical codes. The CP values obtained from Autoform® quasi-static solution are compared with Abaqus® transient forming analysis solution. Topology optimization is applied on the lower die by using the estimated CP loads. Von-Mises stress, elastic deformation and volume are compared between current and optimized die geometry. Panel thickness variation is also investigated in longitudinal and transverse directions.

Effect of Surface Modification and Fibre Content on the Mechanical Properties of Coconut Fibre Reinforced Concrete

Abstract: In the past few decades, concrete has been the most widely used material for structural applications in the world and uses steel reinforcement as aide to meet the flexural, tensile and ductility demands required of concrete structures. Manufacturing of concrete and steel reinforced concrete structures is associated with millions of tons of carbon dioxide emissions and mineral waste. This activity is also responsible for the depletion of a large number of non-renewable resources. Reinforcing steel is also a high cost material, consumes a lot of energy in its production. Consequently, the use of natural fibres as an alternative for steel reinforcement is widely investigated, to promote the use of sustainable concrete structures. This study aims to investigate the effect on durability, flexural, compressive, tensile properties and workability of concrete by incorporating coir fibre at varying fibre content to find the fibre content which gives optimum results. The fibre contents used were 0%, 0.5%, 1.0%, 1.5% and 2.0% by weight of cement. Furthermore, the effect of modifying the surface of the coir fibres by alkali treatment (i.e. 5 wt.% NaOH solution) and coating the fibres with epoxy paint and polyurethane varnish on coir fibre reinforced concrete (CFRC) were also investigated. Tests conducted on the CFRC specimens included slump test and flexural, compressive and tensile strength tests. Water absorption and sorptivity tests were also conducted to investigate the durability. Slump (workability) and unit weight reduced with an increase in fibre content. The surface modification methods used, had resulted in an increased workability and a reduced unit-weight. A coconut fibre content of 1% produced the best combination of flexural, tensile and compressive properties. Water absorption and sorption rate per unit time, increased with an increase of coir fibre content. It is also found that epoxy paint and alkali treatment of the fibres has a positive effect on the mechanical strength properties and also the durability and workability of the CFRC specimens. However, polyurethane varnish coating had a detrimental effect on the mechanical strength properties of the CFRC specimens.

Production of Bulk Metallic Glasses by Ultrasonic Welding of Nickel Based Amorphous Ribbons

Abstract: With the evolution of society new materials or classes of materials must be developed. The metallic alloys with amorphous structure have exceptional physical properties due to the spatial order of the atoms in structure and the absence of crystalline defects such as dislocations, grain boundaries, etc. Due to the metastable states in which these alloys are located, obtaining bulk materials from amorphous metal alloys is difficult, being limited to simple geometries and high production cost. This problem can be solved by using the ultrasonic welding of amorphous ribbons for the production of bulk metallic glasses.In this paper, we aimed to produce bulk metallic glasses materials by welding the ribbon packages in ultrasonic field. In order to prove the preservation of the amorphous structure of both the primary welding alloys as well as after the welding of the amorphous ribbons, Differential thermal analysis (DTA), X-ray diffraction (XRD), Scanning electron microscopy (SEM) analysis were carried out. Vickers micro-hardness test was also performed in order to reveal the mechanical properties in the welded joint.

Evaluation of the Cavitation Resistance of INCONEL 718, in Delivered and Respectively Heat Treated Condition

Abstract: Inconel 718 is a very difficult metal for machining because of its high plasticity. Lately, more and more researchers are interested in using it for cavitation parts, such as the plugs and drawers of the valves. For this purpose, thermal volumetric treatments have been initiated to facilitate mechanical machining, aiming simultaneously to obtain good compression and cavitation resistance results. Therefore, this paper presents the results of cavitation erosion behavior and cavitation resistance of ICONEL 718, subjected to two thermal treatment regimes, differentiated by the duration (temperature 800 °C and residence times 5 hours, and respectively 10 hours). The assessment of the cavitation resistance provided by each heat treatment regime is based on the average durability cavitation parameter, as defined by K. Steller. The research is achieved by using the standard vibrator device with piezo - ceramic crystals from the Cavitation Laboratory of the Politechnica University of Timisoara.

Thermal and Mechanical Influence of Ultrasonically Aided Electrical Discharge Machining on Co-Cr Alloys

Abstract: The paper reviews machining of CoCr alloys by electric discharge machining and ultrasonic aided discharge machining. The removal mechanism is discussed, modeled with Comsol Multiphysics and validated using experimental data.

Temperature Effect on the Modal Frequencies of Aluminum Honeycomb Plate

Abstract: The aim of this paper is to perform a study on how the elevated temperature and gradient of temperature affect the natural frequencies of aluminum honeycomb plate. This study is carried out for temperature range between 200K and 800K, and gradient temperature (ΔT) across the thickness direction of the plate between [0-500K]. Different honeycomb plate geometries have been selected for the analysis, by changing the core thickness, skins thickness and cell size. The obtained results show that the effect of the temperature is noticeable. At temperature 800K, the natural frequencies decrease by 16.1% in comparison to their values at ambient temperature (300K). That means, high temperature makes the material suffers from weak rigidity, which furthermore contribute to high decrease of all the frequencies. In addition, investigations carried out in this work relate to the modal analysis of the honeycomb plate, under various gradients of temperature across the core of the plate. The obtained results show that the gradient of temperature has an effect on the modes of vibration of the honeycomb plate. This effect becomes significant when the gradient of temperature is very high. At ΔT equal 500K, the natural vibration modes decrease by 9.5% in comparison to the case where no gradient of temperature (ΔT = 0K) is applied between the two faces of the plate. Keywords: honeycomb panel; aluminum; natural frequency; finite element method; temperature.

Experimental Investigation on Microstructural and Wear Behaviour of Dual Reinforced Particles (DRP) Aluminium Alloy Composites

Abstract: In the present scenario, the automobile industry, and aerospace industries are considerable scuffles to strive for innovative lightweight materials among manufacturing industries. They preserve their place by reducing the cost of their products and services. For this tenacity, the demand for lightweight material, low cost, and high-performance material are needed. Aluminum matrix composite is developed to fulfill and becomes an engineer’s material. Aerospace & Automobile industries are eager to introducing compound aluminum metal matrix composites due to their excellent mechanical & tribological properties which makes a reduction in the weight of the component. In this project the LM13 as the matrix material while SiC and B4C have been considered as dual reinforcement. Stir casting is the modest and inexpensive method of fabricating an aluminum matrix composite. For the Evaluation of Mechanical &Tribological behavior of DRP composite castings (LM13/B4C/SiC) selection for experimentation tests. In this paper different specimens of the MMC with LM13 Al Alloy 2wt% SiC and 2wt% B4C, 2wt% SiC and 4% B4C, 4wt% SiC, 2wt% B4C, 4wt% SiC and 4wt% B4C are taken for carried to invention out the increase in DRP in the composites will intensification the mechanical properties of the LM13 Al Alloy SiC and B4 C composite formed.

Inspection and Repair Quality Plan of Regeneration Gas Heater

Abstract: Gas heaters used in oil and petrol industry transfer heat to the produced gas stream. Heaters are especially used when producing natural gas or condensate to avoid the formation of ice and gas hydrates. In this work, the inspection practices for process heaters used in petroleum refineries and petrochemical plants is presented as well as critical places for crack formation. After the inspection of the Regeneration Gas Heater the cracks were found and immediately repaired. The inspection is performed using visual, liquid penetrant and ultrasonic testing. The inspection and plan repair by welding is covered according to API 573:2013 and ASME IX:2017. In this work, the results before and after repair are presented and discussed.

Assessment of the Cavitation Resistance of Stainless Steel X5crni18-10, Subjected to Thermal Sensitization Based on Average Durability

Abstract: Among the uses of stainless steel GX5CrNi18-10 one mentions the hydraulic machine blades and the rotors, which are highly susceptible to cavitation. To achieve a long life service under cavitation conditions, the pieces made of this steel are subjected to volumetric thermal treatments, which change the structure and mechanical properties. In this paper, one presents the results of the research concerning the behavior and the resistance to the cavitation erosion of the thermally sensitized GX5CrNi18-10 stainless steel, applying four different temperature regimes (two at 650°C and two at 750°C) and different durations (30 minutes and respectively 60 minutes). The results are presented in the form of cumulative mass loss curves M (t) and erosion rate v (t). The assessment of the cavitation resistance provided by each heat treatment regime is based on the average durability cavitation parameter, as defined by K. Steller. The research was conducted on the standard vibrator with piezo-ceramic crystals from the Cavitation Laboratory of the Politechnica University of Timisoara.

Earth Abundant Metals as Cost Effective Alternatives in Photocatalytic Applications: A Review

Abstract: In a quest for a cleaner planet and to have alternative forms of energy generation apart from the fossil-based power supply, fuel cell technology has emerged as an alternative energy source for usage across all economic sectors. The application of this age-old technology is found in alkaline (AFC), molten carbonate (MCFC), phosphoric acid (PAFC), polymer electrolyte membrane (PEMFC) and solid oxide (SOFC) fuel cells. These fuel cells are named based on the type of electrolyte employed in their applications and the fuel of choice for energy generation is hydrogen. This fuel can be used in its pure form or extracted from other sources such as methanol, water and syngas. Ammonia in its liquefied and gaseous forms may be used as a non-carbonaceous fuel for the hydrogen source in some of these fuel cell technologies due to its safety, lower price, ease of storage and transportation. In this review, all the fuel cells will be investigated in their capability of using ammonia as a direct fuel. The role of earth abundant metal catalysts in comparison to TiO2 was evaluated in terms of molecular orbital theory and in the decomposition of organic compounds and other material into nitrogen and hydrogen products under the visible light radiation. The p-orbital participation in earth abundant metals or metal oxides doping, emerged as a strong contribution to bandgap attenuation.