Search

This paper presents the results of an experimental investigation into the Ultimate Elastic Wall Stress (UEWS) of ±55° filament wound composite pipes. The UEWS test appears to provide an attractive alternative to the current method, and has proved to be one of the most effective in term of accuracy and speed. Moreover, it has been found to be sensitive to changes in key manufacturing and raw material parameters. The pipes were subjected to biaxial loading, which was achieved by combinations of hoop and axial stress. Loads were applied as groups of cycles which, were gradually increased until the UEWS had been determined. Various ratios of hoop to axial stress were applied to the pipes, ranging from pure axial to pure hoop loading at room temperature and at 65°C. These ratios were investigated by applying different pressures in both the main and small chambers built inside the pipe, and therefore it was unnecessary to add any external loads to the pipe wall. Tests were also conducted to observe leakage through the pipe wall. The main failure mode observed was weepage through the pipe wall, which was due to intensive matrix microcracking. The results from the UEWS tests are presented in the form of failure envelopes showing the effects of testing at an elevated temperature. Finally, degradation in the elastic properties of the pipe wall is also discussed and plotted against wall stress.

According to the mechanical simulation intelligent control theory, and combining the character interaction principle, the use of genetic algorithm carries out an in-depth analysis and research for the process of PC MCU automatic control, and then the control algorithm of interactive genetic is established, finally we design the VGA structure circuit. In order to validate the validity and reliability of the model and control circuit, this paper uses the medical micro robot as the research object to the experimental analysis for the delay control circuit, so the delay characteristic curve will be obtained. By the control of time delay curve, we can be seen that the scanning delay of controllable voltage can control delay in the range of 22ps-60ps, it meets the design standards, to provide the theory reference for the mechanical bionic intelligence automatic control research.

The main research content of this article is to design a direct sequence spread spectrum communication system based on software radio technology. In this paper, design of spread spectrum receiver system directly to intermediate frequency sampling signal processing, after internal processing directly output transmission baseband signal information.

A grinding wheel wears rapidly during ultrasonic assisted surface generation of a large aperture aspherical RB-SiC mirror, which leads to an increase of grinding force and profile error. In this paper, different types of resinoid bonded diamond grinding wheel with a same grit size were dressed with high-pressure abrasive water jet. The dressing effects of abrasive water jet were assessed through comparing the 3D roughness of the grinding wheel topographies before and after dressing. The experimental results show that diamond grits of a worn grinding wheel are protruding from bond after dressing. The feed rate of nozzle and the bond materials have significant impact on the 3D surface roughness of the wheel and dressing efficient. The softer binder and the decrease of the feed rates and lead to deeper grooves during dressing of grinding wheel. However, too low feed rate will make a large number of abrasive particles drop from binder, which worsens the wheel topography. Therefore, to dress grinding wheel well and efficiently, optimized feed rate must be chosen. (2014) Trans Tech Publications, Switzerland.

This paper presents optimisation of hot press forming using design of experiment for high hardness properties at maximum cooling water temperature and minimum quenching time. Samples were boron steel blanks of 60x50 mm dimension. Hot press forming was conducted using a hydraulic press machine with 20 tonne maximum load. Results of this research work show that parameters obtained by single response optimization through desirability analysis route will increase hardness by 66.72%. The hardness properties of samples were between 477 and 551.4 HV(0.1). These findings were important to design tailored ultra-high strength automotive components at different process parameter settings and to reduce production cost consumption and improve production rate.

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.

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

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.

This paper contains results of tests performed in order to determine mechanical properties of steel P460NL1, used as filler material during the execution of welded joints. Arc welding of samples from which the specimens were taken was carried out through the application of welding process 111, because it is one of the processes for the execution of pipelines for pressure equipment. Microspecimens with diameter of Ø1,5 mm were tested in order to determine tensile properties of material taken from the heat-affected zone and weld metal, while specimens with diameter of Ø6 mm were tested in order to determine tensile properties of parent material. Standard Charpy V-notch specimens were used in order to determine impact energy. Results of metallographic tests which refer to the structure of a pipe welded joint are also presented.

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.

The paper presents the assembling flux of thermocouple-instrumented nuclear fuel element for research reactor, from the point of view of the welding / brazing engineer, considering nuclear quality and safety requirements: fuel element structural reliability (no radioactive leaks through joints) and temperature signal reliability (thermocouple sheath integrity), this signal being an essential parameter for reactor normal operation and emergency shut-down. The paper is a real case study for an experimental instrumented element recently developed at INR-Pitesti describing technology choices as balance between fabrication complexity and risk of failure in joining processes, especially in later stages when added value increases. All joints (welded or brazed) fall into microjoining category, and it is shown how some special provisions may influence reliability. Focus is put on brazing thin-walled Inconel sheathed thermocouples, where erosion and local loss of ductility are known issues, leading to sheath rupture. Choosing as filler the less aggressive BNi-9 helped too little. A simple but efficient technique has been developed to address this matter adequate to narrow spaces inside a nuclear fuel element, where no room is available for solutions described in literature e.g. distal preplacing of filler. The solution prevents sheath from having prolonged contact with large volume of molten filler by using locally a miniature barrier (thin stainless-steel coil or sleeve) which only allows capillary wetting, being also a perfect real-time visual indicator of brazing progress and completion. As proved in the present paper, this method along with using filler formulation with lower Carbon content (without organic binder) enhances significantly, 8 times at least, resistance to bending fatigue. A particular vacuum brazing chamber design is employed: narrow quartz tube with external induction coil and top fitting letting outside the long thermocouples attached, reducing much the chamber volume and degassing. Careful impedance match is therefore required to overcome induction power loss due to the larger coil-to-workpiece gap. Additional joining problems are discussed e.g. inherent differential expansion of long parts during induction heating which afterwards may put tension upon braze during solidification and determine delayed cracking, this being avoided through wise order of operations. Another concern is the final precision weld between instrumentation segment having attached the hard-to-handle long thermocouples bunch and nuclear segment with the heavy Uranium pellets. The result of this research is successful assembling of first Romanian prototype with joints exhibiting He leak rate bellow 1E-09 std.cc/sec and overall reliability proved during reactor irradiation testing.

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.

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.

In this paper, heat affected zone characteristics of DP1000 steels was investigated during diode laser beam welding (LBW). A butt-welded joint of specimen in dimension of 300 x 150 mm each (according to EN15614-11:2002) with 1 mm thickness is used for the experimental purpose. The welding thermal cycle and the cooling circumstances in the HAZ was determined by real experiment and the physical simulation. A Gleeble 3500 thermo-physical simulator was used to physically simulate the coarse grain heat affected zone (CGHAZ) on the base material specimens by the utilization of the thermal cycles for t8/5 =2.5 s. The results of the physical simulation were validated by real welding experiments. The properties of the simulated and the real HAZ was examined by optical microscopic, scanning electron microscope and hardness tests.

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.

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.

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.

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.

This paper presents experiments regarding the welding with electron beam of multiple overlapping Ni-based amorphous ribbons produced by "Planar flow casting" method [1]. Welded samples were performed, using the electron beam welding equipment “Chamber Machine EBG 45-150 K14” [2]. The welded joints were analyzed by SEM, EDX, XRD in order to optimize some technological parameters to avoid deterioration of the amorphous ribbons during the welding process [3].

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.

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.

The paper presents studies carried out in order to determine the causes of destruction, by cracking, of a crankshaft from the composition of a tractor used to process soil.Experiments were carried out in two directions, namely a step by step study on the degraded area and a investigation into the operating conditions of the machine, on that specific work cycle.The degraded shaft was investigated visually at a magnification of 10x and by hardness tests on the areas with embrittlement cracking.Hardness test enfolded large variations (in hardness), of up to 40%, leading to a high sensitivity to cracking by mechanical fatigue, induced by the structural tension concentrators. However, hardness examination did not reveal areas of shaft degradation due to fatigue, which determined us to study the operating conditions. The shaft cracking occurred during soil processing, using a multilayered plow and in difficult exploitation conditions.Variations of mechanical characteristics of soils in the area of ​​operation of the machine, is relatively large, fact which corroborated with the lack of safety elements when overloaded, of the endowment of the tractor-plow system, led to the overcoming of the permissible load, which on a background of high hardness material, determined the embrittlement cracking of the crankshaft. Research performed highlighted, for the area in which the machine activates, the necessity of introducing in the power-generating system of safety and protection elements to prevent the destruction of components.

Research conducted aimed to compare the hybrid ultrasonic-thermal cutting technology with the classic thermal cutting one. The experimental program was carried out on the ISIM designed hybrid equipment, operating at a frequency of 35 KHz, with a cutting geometry of the ultrasonic horn - sonotrode and the thermal anvil designed specifically for the task at hand; the first phase of the experimental program was developed on the thermal cutting module, the second one was performed on the US-thermal hybrid module, both modules being part of the hybrid cutting equipment designed and patented by ISIM Timisoara. The research performed in this present paper, intends to highlight the benefits of the hybrid cutting technology when compared to classical thermal cutting, in order to process two types of materials with different specifications and dimensions. After visually inspection cut materials have been then compared with automotive seatbelt quality standard IATF - International Automotive Task Force 16949. Experiments highlighted that hybrid ultrasonic-thermal cutting process has a significant influence on the quality of processed materials when compared to classic thermal cutting process, which in some cases makes the materials unsuitable for use in the automotive industry. The paper further presents two types of technology data sets suitable for 2 types of materials and up to automotive industry requirements.

A grapple is a device that includes at least one gripping arrangement. The gripping arrangement is configured to grip and traverse objects so as to reach a desired location on site and to anchor it, therefore allowing the work to be carried out. [1] A method for controlling the fill volume of a grapple, such as a bulk-material crane grapple which includes at least one hoist-and-closure unit, may include adjusting the fill volume of the grapple is during the grapple closure process by adjusting/controlling the grapple hoist height. The grapple hoist speed and/or grapple hoist height may be the controlling parameter for the adjustment of the fill volume of the grapple. [2]Grapples geometric configuration is established by calculating the useful load mass. In the experiments performed in the present paper the load mass was 3000 kg. In exploitation, in cases where relatively low density materials, if compared to standard materials, are being moved/processed, changes to the volume capacity must be done; [3] changes that need to be correlated with the new materials and the exploitation conditions.The tractor attachment is a grapple assembly, and the grapple assembly kit includes a mounting assembly, a plurality of clamping units, and a plurality of support units. [4] A connection system for coupling an claw to a work vehicle includes a receiver assembly that needs to be implement and configured to a connector assembly of an arm of the work vehicle. [5]The solution developed by the authors consists in prolonging and consolidating the active elements of the grapple, by equipping it with additional elements that take and process load tensions, in the present case hard wood logs; and a consolidation and protection system that protects it from wear, that mostly appears when the hook crane repeatedly hits the ground in order to collect the deposited logs.The additional elements for handling and processing logs are made out of low alloyed steel, thus by configuring the tips we assure the good gliding of processed materials on the active/used surfaces. The self-protection system to wear is made out of boron micro-alloyed steel sheets that have hardness values up to 500 HB. Joining the grapple ensemble with specialized elements was performed through welding.

The paper presents technologies for the manufacturing of modulated bi-metal elements, used as interchangeable reinforcement, according to patent RO129865. The bi-metal was developed by surface build-up of functional layers that have increased hardness, on a low alloyed steel substrate, so as to ensure maximum lifespan in exploitation. Welded layers deposited on active areas has a thickness of 3 mm and have high hardness (about 50-60 HRC) in order to ensure a good resistance to wear by abrasion, possibly combined with fatigue, erosion or corrosion. The modulated elements sizes are equal to or higher than the wear additions, up to 10%, being dimensioned on the principles of preventive-repetitive maintenance. The interchangeable bi-metal elements are welded on the steel components of machines, used for hot or cold processing of parts and semi-finished products manufactured in series.

In this paper, the hot compression tests were performed to study on deformation-induced pearlite transformation in vanadium microalloyed eutectoid steel. The results showed that volume fraction of deformation -induced pearlite were higher and the pearlite were spheroidized better under lower strain rate and higher strain in vanadium microalloyed steel. Ferrite grains and granular cementites were further refined through vanadium microalloying combined with deformation-induced pearlite transformation .Vanadium dissolved in γmatrix could retard deformation-induced pearlite transformation under low strain, vanadium carbides precipitated due to strain-induced precipitation eliminate the retardation when the strain was increased to a certain extent. Under heavy deformation, ferrite grains and granular cementites in vanadium microalloyed steel were finer compared with vanadium free steel.

This paper represents a comparative study of the different weave structures of jute woven fiber reinforced unsaturated polyester resin (UPR) composites. The weave structures were selected as plain (1/1), twill (2/1), twill (3/1) and basket (2/2). Composites (50% fiber by wt.) were prepared by using hand lay-up technique. The mechanical properties such as tensile strength (TS), bending strength (BS) and impact strength (IS) of the composites were evaluated and compared. It was found that basket weave/UPR based composite showed the highest mechanical properties. The optimum value of TS, BS, TM, BM and IS of the composite were found to be 47 MPa, 80 MPa, 1.4 GPa, 4.8 GPa and 27 KJ/m2.To find out the effect of yarn density on mechanical properties of the composites, 2/1 twill structure was selected and found significant improvement in the mechanical properties with the increase of Ends/Inch (EPI) and Picks/Inch (PPI) in the fabric. Water uptake and degradation behavior in aqueous medium of the composites was also observed.

This paper examines and present the findings of the physical and mechanical properties of concrete containing rice husk ash (RHA), and the blend of rice husk ash with calcium carbide waste (RHA-CCW). Concrete cubes, cylindrical and beam specimens containing different percentages of RHA and RHA-CCW by weight of cement (5, 10, 15 and 20 %) were cast. Compressive strength test was carried out after the specimens were cured in water for 7, 14, 28 and 56 days. Test for tensile and flexural strength was carried out after 28 days curing. Initial and final setting time test was carried out on mortar specimens with the same percentage of RHA and RHA-CCW. Bogues model was used to determine the elemental and compound composition of cement when blended with the RHA and RHA-CCW. From the results obtained, the compressive strength of RHA-CCW concrete increases as cement is partially replaced with RHA-CCW content, with the maximum strength attained at 5 % replacement. RHA concrete attains it maximum strength at 10 % replacement. The maximum compressive strength results obtained for both RHA and RHA-CCW concrete were higher than the strength of plain concrete (0 % replacement) by 1.1 % and 14.7 % respectively. Interestingly, results obtained for the tensile strength also shows a similar pattern of strength development with that of compressive strength. The flexural strength properties of concrete was improved upon when RHA-CCW was used in concrete compared to RHA. The results of setting time test for RHA mortar showed a decrease in setting time, while the reverse was the case for RHA-CCW mortar. In conclusion, provided adequate curing is maintained, the used of RHA-CCW gives a better performance in concrete than RHA. However, they both perform better in concrete than the plain, and can be used as additives in concrete production.

Studies have revealed that wood ash cement concrete just like other pozzolanic cement concrete has lower early strength compared to plain cement concrete. Nanoparticles have been found to improve the early strength of concrete due to its small size and large surface area. This paper reports the findings on influence of nanosilica on the workability and compressive strength of wood ash cement concrete. Wood ash was obtained as a waste product from Ladoke Akintola University of Technology (LAUTECH) bread bakery, Ogbomoso. Biological synthesis of nanosilica using kola pod extract and silica precursor (1:5) was conducted at Nanotechnology research group laboratory at LAUTECH. The chemical composition, specific gravity and grading of wood ash, fine and coarse aggregate used were determined. Concrete with 10% wood ash replacement for cement was produced using 1:2:4 mix proportion and water to binder ratio of 0.5. Nanosilica was added at 0.5, 1.0, 1.5 and 2.0% levels. Concrete with no wood ash and nanosilica served as the control. Workability and compressive strength of the plain and composite concrete were determined. The results showed that concrete workability was enhanced with introduction of nanosilica. The compressive strength also increased with the addition of nanosilica. Maximum compressive strength of 27.53MPa was achieved at 90 days with 1.5% nanosilica addition. It was concluded that nanosilica enhanced workability and improved both early and later strength development in wood ash concrete with 1.5% as the optimum addition.

The papers aim is to detail temper bead realization, as a possible solution to the removal of heat treatments. Applying temper beads could be a solution for repair, in case surface heat treatments are required, provided they are correctly applied. The paper presents the main ways of applying temper beads, presenting in the same time what the outcomes could be in case of not respecting the prescribed work sequence.

The paper will try to evidence the importance and the role of the Welded Structural Designer and explain also the critical joints to the dynamically loaded welded structures susceptible to fatigue. In case of the important structures the decision of the Welded Structural Designer is essential, because his decision allows the change the type of joints, the type of materials.

In recent years, due to its extraordinary qualities, friction stir welding process FSW has found its utility in more and more industrial applications in fields such as: aerospace, aeronautics, naval, automotive and railway. The paper summarizes several achievements in the FSW joining of couples of similar and dissimilar materials used in the automotive industry. There are presented aspects regarding the welding of ferrous metal materials (DD13), couples of non-ferrous metallic materials (Al Cu range) and steels with aluminum. The behavior of FSW of material couples in terms of analysis of microstructural improvements and mechanical characteristics is analyzed. The preliminary results obtained have shown that the FSW process can be successfully applied to the joining of the approached material couples, but with the use of optimized welding tools and technologies.

Turbine and generator rotors and shafts undergo high stresses during regular working life and, from a safety and operational aspect, are the most significant components of a power generation system. Depending on the appropriate operating conditions, like temperature and/or corrosion the, shafts can be fabricated out of low/high alloy heat resistance material or of low alloyed, highly toughened material for different application. Despite known good practice and developed operation procedures, the failures of shafts sometimes occur. The right and well-defined failure analysis is the basis for feasibility analysis of repair method in the power generating industry. The analysis of direct and indirect costs of repair after the failure analysis as well as the analysis of the repair and post-repair conditions of the repaired element is the vital for decision on the key question. Is it possible to repair this element and what is the optimal repair strategy? This paper compares and analyses two approaches, by weldability analysis and weld cycle simulation, in order to determine welding feasibility analysis of cracked hydro turbine shafts.

The paper presents the current state of researches carried out in order to improve homogeneity of mixtures for metallic powders; our priority is those with different participation in the mixture, by mechanical alloying. Mixtures of this type are used in the production of welding and related materials.Recently, research has been done to improve deposited metal properties by welding with coated electrodes, by depositing nanostructures, with uncertain results due to the low degree of homogeneity of blends involved in the electrode coating.The performance enhancement method for coated rods, developed by introducing in their coat activating precursors, used for brazing, is well known. The solution to improve the degree of homogeneity of alloying systems by mechanical alloying has been successfully applied for the manufacture of coated electrodes and those tubular with a composite core which are deposited by manual welding or TIG welding, type Fe25% Cr-4% W-V-Ti-La. The grouping of powder components for mechanical alloying was done in such a way that, finally, we have groups with the granulation, respectively specific weight, close and a low potential of segregation.The method of mechanical alloying of the components was used in the manufacture of coated rods in order to improve the fluidity of silver-rich buffer layers deposited in order to favor the diffusion phenomena of brazing alloys in the base materials.Testing the homogeneity of the alloying systems was performed indirectly by metallographic analysis and sclerometric tests.

The ultrasound processing is in continuous development, always bringing better technological solutions. Ultrasonic welding occupies an important place within this category of processing. The present study focuses on some piezoceramic materials that represent the active elements in the structure of the required energy generator on which ultrasonic welding is based in fact. Using the analytical method of investigation, several aspects of piezoceramic material structural behavior during the exploitation were followed, both at macroscopic and microscopic level. Some causes and effects of changes to their functionality have been analyzed. The paper concludes with observations and recommendations on optimizing the manufacture and use of piezoceramic materials intended for converter construction for ultrasonic welding.

Existing equipment units in specialized industry market, used to process composite polymeric materials, are made with constructive solutions dedicated to specific applications, actual cutting operation are being achieved by thermal effect often resulting in burns of the material on the working area, the version proposed in this paper, a hybrid technology using ultrasonic energy assisted thermic energy, proved to be an excellent solution.The technical problem solved by solution presented by our technology is represented by real market necessity of providing clean processing – in this case cutting and sealing, of composite polymeric materials, in the form of strips, which must correspond in dimensional and qualitative terms to specifications in product documentation, textile tape, used in the textile, food, medical and army industries.

We approached a new hybrid technology that integrates ultrasonic energy with FSW welding. By integrating ultrasound in the FSW process, a number of benefits are expected in terms of welding quality, forces and tool life. Our research aimed at developing a new technique of friction stir welding assisted by ultrasonic energy, namely FSW-US, which can improve the process, it can contribute to the decrease of forces that develop during the welding process and can increase the quality of welded joints. Metal welding and processing technologies that use ultrasonic vibrations, either as a primary source to achieve prescribed performance, or as a source of assistance to improve the efficiency of the operation and product quality, are currently being researched or discussed in the international scientific environment. The present paper analyzes the effects of overlapping ultrasonic vibrations with heat generation, temperature distribution and material flow generated by applying the FSW process. Mechanical effect plays a dominant role in the welding process assisted by ultrasonic vibrations, while thermal effects are insignificant. Overlapping ultrasonic vibrations on the friction stir welding process can produce a stream of improved plasticized material, increases the welding speed and efficiency, it can also improve weld quality by increasing the flow / volume of plastic material around the tool. [1]

In certain welded constructions (e g. trails pipes) the weld root is no longer accessible after its completion. As a result, the weld root defects cannot be visually observed. Under these circumstances the root must be examined with ultrasounds on the other accessible side of the seam. The paper .presents the results of the flaw examination which was subject to an pipe, butt welded, made it with coated electrodes

This paper presents experiments regarding the welding with electron beam of Ni based amorphous ribbons produced by "Planar flow casting" method with the aid of "Politehnica" University of Timisoara equipment. Welded samples were performed in partnership with Graz University of Technology, Institute of Materials Science, Joining and Forming, using the electron beam welding equipment “Chamber Machine EBG 45-150 K14”. The welded joints were analyzed by SEM, EDX, XRD in order to optimize some technological parameters to avoid deterioration of the amorphous ribbons during the welding process.

The paper presents three applications for maintenance of soil processing tools, achieved by loading through welding of rough layers, of the active surfaces, highly subjected to wear. To achieve this objective we used the preventive repetitive maintenance principles and the concept of fair definition of the wear additional material, in such a way that the rendering activity of active surfaces with the additions will take place in the „dead time” for the manufacturing operation. In concrete situations, of preparing and processing soil, to assure the good functioning of cutting tools in contact with the soil to be processed, in quarries that extract and process basaltic rock aggregates we used a common process of depositing wear protection layers or intelligent self-protection systems, by melting with electric arc of new welding materials that assure in the deposited metal, type Fe-25%Cr-4%W-1%V-Ti-La, hardness of approx. 55HRC and a good welding compatibility with a large palette of low alloyed steels or micro-alloyed with boron, with hardness up to 400 HB. The structure and morphology of the deposits are type austenitic with a high volume of complex carbides of chromium, wolfram and vanadium and reduced, clean inter-crystalline areas, determined by the presence of lanthanides, fact that assures the intelligent protection systems a high tenacity and a good resistance to abrasion wear, specific clay soil with a high content of quartz sand, present in the vest area. The recent change in soil processing systems, by introducing new equipment, determined a rise in wear conditions, especially for scarify and plow coulters teeth and hoeing digger used for growing crops, respectively of useful technologies used in exploitation in conditions of high productivity with low costs.

The paper presents the characteristics of TiO2 coatings realized by HVOF spraying process by two different processing paths, i.e. using the classical method of preparing the substrate by sandblasting and by applying a fast laser texturing of the substrate (instead of sandblasting) before the actual HVOF spraying respectively (a duplex treatment). The obtained coatings’ morphology were characterized by SEM before and after electrochemical measurements in NaCl solution. The textured sample presented better resistance to corrosion compared with classical processing path. Keywords: coatings, fast laser texturing, HVOF spraying, duplex surface treatment, anticorrosive.

In this paper, the Mg-Al hydrotalcite-like compound (Mg-Al-HTLC) was synthesized by hydrothermal method at 373K. Structure and morphology of Mg-Al-HTLC was obtained with X-ray diffraction (XRD), scanning electron microscope (SEM) and Fourier transform infra-red spectroscopy(FTIR). A series of polar and non-polar molecules were used for probes, surface properties of Mg-Al-HTLC was studied by inverse gas chromatography (IGC) at 353K, 363K, 373K, 383K respectively. The retention volume was utilized for evaluating the free energy of adsorption (-ΔGSP), the dispersive component of the surface energy(γsD), as well as the enthalpy and entropic component(ΔHSP, -ΔSSP). XRD results reveal that the Mg-Al-HTLC has high crystallinity and perfect layered structure. The results of IGC show that Mg-Al-HTLC would adsorb straight-chain alkanes spontaneously, and the values of γsDwere similar at all temperature. It reveals Mg-Al-HTLC is a material with particular characteristics of both acid and base. This study illustrates that, as a method to evaluate the surface properties of material , IGC method is dependable and significant.

In this paper, a mixture of commercial Al2O3 and Y2O3 nanopowders was prepared according to the stoichiometric ratios of YAG (Y3Al5O12) with 0.5 wt% tetraethyl orthosilicate (TEOS) as a sintering aid. The effects of air and vacuum sintering atmosphere were examined on the phase transformation, densification, in-line transmission, microstructure evolution, grain size distribution, sintering trajectories, and grain growth map of the YAG ceramics. The results showed that all samples were pure YAG phase. Nearly pore-free microstructure (99.8%) and narrow grain size distribution (4-10 μm) with an average grain size of 7 μm was obtained for the sample sintered in the vacuum atmosphere, while both inner and inter pores with abnormal grain growth, wider grain size distribution (9-27 μm) with the average grain size of 12 μm were detected in air atmosphere. Also, the results showed that the specimens sintered in vacuum atmosphere had higher relative densities and smaller grain sizes at all sintering temperatures for 6 h. The maximum transmittance at 1064 nm of the YAG ceramics sintered at air and vacuum atmosphere was 26% and 68%, respectively.

Aqueous liquid radioactive waste is generated during nuclear reactor operations and during industrial and institutional application of radioisotopes. The immobilization of radioactive waste in Portland cement matrix is the most used method, applied in the world by the countries developing nuclear energy programs. The conditioning of the radioactive wastes by cementation process imposes the structural investigation by X-ray diffraction (XRD) of the samples prepared with cement and different ratio of concentrate. This paper gives useful information about the influence of complexing agents related to damages produced in concrete microstructures.

This paper shows the results of the mechanical characterisation of a series of new sustainable polymeric formulations filled with almond shell and cellulosic fibres for its use in rotomoulding process. Up to ten formulations of polyethylene and polycaprolactone, were developed with a content from 10 to 40 wt% of natural filler. The addition of these fillers decreased the mechanical properties, mainly when the formulation was carried out by physical mixing. However, good interfacial interaction between the polymer and filler was produced in the compounding process, obtaining final formulations appropriated for rotomoulding.

Mica-based pearlescent pigments are widely applied in plastics, cosmetics, automobiles coatings and other fields, but very few applications in high temperature field are found as their poor heat resistance. In this paper, phlogopite is chosen as a new substrate which is coated by Fe2O3(doping with La3+) in order to improve the high temperature resistance and luster of the new developed pearlescent pigments. According to the X-ray diffraction (XRD) and scanning electron microscopy (SEM) results, it is found that Fe2O3nanospheres were coated on the surface of phlogopite homogenously. Colorimeter data imply that doping La3+can improve the color saturation and purity of pigments apparently. And the optimum amount is 3% lanthanum nitrate addition in this work.

The use of agricultural wastes and natural materials in new technologies is a novel subject. Consequently, an attempt has been made to formulate a synthetic fluid using an organic water, Water Extract from Fermented Ground Maize (WEFGM) and compare its performance with water-based sample in turning operation using a mild steel as workpiece. Two samples of synthetic fluids were formulated from each of deionized WEFGM, ordinary WEFGM and deionized water as base-fluids at two composition (5 and 10%vol) levels of selected additives. The results of experimental analysis of heat transfer properties of these synthetic fluids exist, hence the need to ascertain the actual performance output. Temperature-Time Gradient (TTG) which is a rate of temperature drop (heat withdrawn) from the work zone was used as evaluation parameters. The result showed that deionized WEFGM is the most efficient of the entire samples at both compositions with an average TTG of 3.61 and 2.16 °C/min at 10 and 5% additive concentration respectively. At lower additive concentration which is more economically advantageous, the performance rating is deionized WEFGM>>WEFGM>>deionized Water. This implies that WEFGM is more effective than water as a base fluid for synthetic fluid in performance as it has been previously so reported in properties. Meanwhile, T-test statistical analysis (using IBM SPSS 23) shows that there is highly significant difference in TTG at each time of application of individual fluid (p0.05) implying that the fluids can all work as coolants and relatively have comparable performance output.

This paper discusses the potentials of different wood constructions for the renovation and extension of existing buildings for sustainable urban renewal. The renovation and extension of existing buildings with wood constructions can contribute significantly to sustainable urban redevelopment. The renovation of building envelopes, such as façades and roofs, with highly insulated wooden components, can reduce the transmission heat losses and related heating energy demand of existing buildings significantly. The extension of existing buildings contributes to the redensification of urban areas and can create synergies with the improvement of existing buildings’ performances. The manifold advantages of specific wooden constructions can be related to different aspects, such as construction type and material properties, building execution, design, logistic and sustainability. The results of this research discuss the architectural design and planning relevant properties of specific timber construction types, such as wood frame, cross-laminated timber (CLT), massive timber, and hybrid timber-concrete, considering the properties of different soft (such as spruce) and hard (such as beech) construction timber species. Timber constructions are compared with conventional massive constructions out of concrete and steel. The results confirm the significant advantages of timber constructions regarding all aspects.

Considering the features of slope rock mass failure, this paper applies residual thrust method and linear programming theory on the basis of finite element method, to assess safety of each cell of slope rock mass in dangerous zone. According to the slip field method to determine three-dimensional slope slip surface, to deduce three-dimensional stability analysis method based on symmetry breaking, a C++ based 3D-slope program is developed for purposes of three-dimensional slope stability analysis. Finally get the most dangerous landslide geometry and its safety factor, In the paper, combining with the engineering examples, the calculating results are comfortable to the practical failure.

Increasingly today we talk about sustainable architecture or, better yet, about adaptive architecture as something innovative. Looking at the past, however, it is possible to find numerous examples of architecture that adapts to the climatic conditions of the place with special devices or natural materials. Starting from the ancient Romans and the ancient peoples of the Middle East, up to the newer system to create energy by exploiting natural resources, are various the adaptive systems of the past. All have in common the respect for the environment, communicating with it sustainably, and optimizing available resources. This paper focuses on some of these systems highlighting the merits.