Transverse Speed Research Articles

60% IACS Conductive Metal Coating on a Polymer Surface: Achievement of a Highly Efficient Additive Processing by Cold Spraying

This paper investigates a current challenge that enables the hybridization of different materials using a solid-state additive principle. We investigate the suitability of such a principle to easily and efficiently grow a metallic electrically conductive coating on a polymer substrate. The additive principle is obtained using the high-pressure cold spraying (CS) method whose literature does not include an achievement as suggested in this paper, that is, to obtain a good conductive copper coating onto polymer with a very high deposition efficiency by tuning the effect of the stand-off distance, transverse speed of the nozzle, and temperature of the carrier gas on the deposition efficiency (DE) in order to overcome delamination and erosion, and thus to improve the DE. A good coating formation up to 400 µm can be obtained, which implies that a standoff distance higher than 100 mm is needed, since both a high gas temperature (400–500 °C) and high gas pressure (30 bars) are required. A nozzle scanning velocity in the range of 200–300 mm/s gives the highest DE. The results reveal that the Cu coating on PEEK reaches a DE up to 91%, leading to an electrical conductivity up to 60% IACS (International Annealed Copper Standard). Thus, parametric analysis, along with the deposition optimization, promises to be feasible for the future in terms of DE improvement along with a good electrical conductivity in CS.

Influence of tool rotational and transverse speed on friction stir welding of dissimilar aluminum 6061 composites

• The study aims to weld the newly developed Al composites. • The FSW is performed based on the design matrix developed using RSM. • The effect of process parameters is studied through the UTS and hardness. • The grain refinement of the composite was significantly analysed by microstructure images. In the present study friction stir welding of dissimilar aluminum 6061 composite is performed. The Al 6061 with B 4 C and Al 6061 with Cr 2 O 3 composite were fabricated using stir casting. B 4 C and Cr 2 O 3 were reinforced in steps of 2, 4, and 6 wt%. The stirring time and stirring speed was maintained common throughout the casting. The preheating temperature of mold and reinforcement is 400 °C and 600 °C respectively. The response surface methodology based design matrix is utilized to perform the welding. The three tool rotational speed and tool transverse speed is used during welding, keeping same weight percentage composite on either side. The W-shaped hardness profile is seen in welding zone having maximum microhardness of 65 HV at nugget zone and minimum microhardness 52 HV at heat affected zones. When the tool transverse speed is increased from 20 to 25 mm/min, an increase in ultimate tensile strength of 59 % is observed.

Experimental study on the cavitation flow and motion characteristics of the vehicle launched underwater

In this paper, an experimental system was independently designed to investigate the cavitation flow mechanism and motion characteristic of the vehicle launched underwater. Conducted experiments based on high-speed photography, and the influence of cavity morphological evolution and kinematic characteristics with the different launch and transverse velocities were analyzed. The results show that cavity shedding phenomenon occurs on different scales. Subsequently, a wide range of pressure impulse on the surface of the vehicle is caused by the collapse of large-scale cavity groups, resulting in an obvious sputtering phenomenon on its surface during the water-exit stage. The more the launch speed increases, the longer the initial cavity length is. Moreover, the moment of completely shedding the cavity delays during the water exit process; Furthermore, with the increase of transverse speed, the attitude angle generally shows an increasing trend, but its growth rate slowed down during the large-scale shedding stage of the cavity.

Parameter optimization of FSW aviation-grade AA8090 using Taguchi grey relational analysis

PurposeThis paper aims to accomplish friction stir welding (FSW) of Al–Li alloy AA8090 to determine optimal settings of the process parameters for higher tensile strength and higher micro-hardness (MH) to achieve the objective of adequate butt-joint strength.Design/methodology/approachAn empirical relation is implemented to govern the utmost influence parameters, i.e. tool rotation speed (TRS), tool transverse speed (TTS) and dwell time (DT). Taguchi grey relational analysis (GRA) was applied for multi-response optimization of response parameters. The grey relational grades (GRs) have been calculated for both the responses MH and ultimate tensile strength to get optimal parametric settings. The variance test has been performed to check the adequacy of the model.FindingsThe Taguchi L9 orthogonal array design was used in establishing the relation between input parameter and output parameter (tensile and MH). TTS and DT have been predicted to be the two most important parameters that influence the extreme quality features of joints by using friction stir welding. Scanning electron microscopy fractography shows the ductile failure of the welded joints.Originality/valueThe experimental trials provided the followings results, maximum ultimate tensile strength (UTS) of 219 MPa and MH 107.1 HV under 1,400 rpm of TRS, 40 mm/min of TTS and 8 s of DT founded the optimum value through GRA.

Investigation of microstructural and wear properties of stir cast and friction stir processed AA 2014-based metal matrix composites

ABSTRACT Due to the major applications in various industries, the global demand for Metal Matrix Composites (MMC) is increasing. The characteristics of manufactured composites highly depend upon the manufacturing method. The present research article showcases the manufacturing of three different compositions, namely AA 2014 + 5 wt.% SiC, AA 2014 + 10 wt.% SiC and AA 2014 + 15 wt.% SiC. A stir casting process has been implemented to manufacture these composites. While implementing the casting process one cannot get rid of the defects that are generated during the solidification. Thus, to avoid these defects in as-cast composites, friction stir processing (FSP) has been performed. FSP avoids casting defects and further enhances the distribution of reinforcement particles. The considered combinations of rotational speed and transverse speed are as follows (i) 270 rpm and 78 mm/min (E1 condition) and (ii) 190 rpm and 50 mm/min (E2 condition). Furthermore, the article compares the microstructure, microhardness and tribological properties of the as-received AA 2014 alloy, as-cast and processed composites. Irrespective of the FSP condition, AA 2014 + 10% SiC composites revealed the highest wear resistance among all the variety of specimens considered for the wear test.

The Influence of the Tool Tilt Angle on the Heat Generation and the Material Behavior in Friction Stir Welding (FSW)

To improve the accuracy of numerical simulation of friction stir welding (FSW) process, the tool tilt angle must be considered as a significant parameter. In this study, specific considerations for mechanical boundary conditions in Eulerian domain is employed to investigate the tool tilt angle influence on the thermomechanical behavior in FSW. Aluminum 6061-T6 with a thickness of 6 mm under a rotational speed of 800 RPM, a transverse speed of 120 mm/min, and a plunging depth of 0.1 mm were employed for the simulations. Results showed an almost symmetric temperature profile predicted by the model without considering the tool tilt angle, while after incorporating the tool tilt angle, the peak temperature point is moved to the tool backside (around 400 °C), resulting in better material bonding, enhancing the weld joint quality. Without accounting for the tool tilt angle, the highest temperature of 389 °C is observed, while with the tilt angle the maximum temperature of 413 °C is achieved. The temperature variations at different points of the leading (around 360 °C) and the trailing sides (around 400 °C) of the welding tool were measured. It was observed that, after considering the tilt angle, as the tool moves, a smooth and quick increase for the temperature at the tool trailing side is achieved. This smooth and quick increasing of the temperature at the trailing side results in reducing the possibility of the formation of defects, cracks, and voids. Finally, comparisons showed that the model computational time is acceptable, and using Eulerian formulation leads to achieving a remarkable accuracy.

Parametric Optimization of Abrasive Water Jet Cutting on AA 5083 through Multiobjective Teaching-Learning Method

The industrial sector is seeing an increase in the development of new technologies on a daily basis. Manufacturing advancements have resulted in low-intensity, inadequate outputs from cutting materials. The application of engineering materials requires cutting to produce the desired shapes and sizes. The material’s fundamental attributes are altered and utilised to improve machinability. Due to its significant benefits over traditional cutting processes, abrasive water jet cutting (AWJC) is now the most popular nonconventional machining for attaining the best cutting of any material. Because of its highly pressurised water power, the substance can quickly be separated from some properties by the use of a small pin with various kinds of abrasives. Due to the time-consuming process of cutting materials, determining optimal cutting conditions for the multiobjective criteria examined is a tough issue in techniques needing large resources. The operational parameters of the abrasive water jet cutting system must be changed in this article to achieve the lowest possible surface roughness while also attaining the maximum possible material removal rate. The abrasive water jet cutting method was utilised in this investigation to see how effectively the AA5083 aluminium alloy could be sliced. Water pressure, transverse speed, stand-off distance, and abrasive flow rate are some of the major cutting parameters that may be adjusted such that the output values such as material removal rate and surface roughness are at their optimal levels.

Tailoring the Microstructure of an AA5754 Aluminum Alloy by Tuning the Combination of Heat Treatment, Friction Stir Welding, and Cold Rolling

Friction stir welding (FSW) has now reached a technological impact and diffusion that makes it a common joining practice for several classes of metallic materials. These include light alloys (aluminum, titanium, magnesium), steels, and other metallic alloys. In addition, the combination of FSW with pre- or post-welding heat treatments or plastic deformation, such as cold rolling (CR), can favor minimal necessary plate thicknesses and induce effective alloy strengthening mechanisms that make the FSW joint lines as plate reinforcing zones. Process parameters, such as pin rotation and transverse speed, can be tuned to optimize the mechanical properties of the resulting joint. This work presents a microstructural study of the mechanical response of different sequences of heat treatment, FSW, and CR in a non-age hardened Al-Mg AA5754 alloy. By using polarized optical microscopy and microhardness tests, two FSW conditions were used to fabricate a joint; and were than subjected to different sequences of heat treatment and cold rolling. The results suggest that FSW conditions have a limited effect on the microstructure, while microhardness profiles show a higher variability of the different datasets related to the low welding speed investigated.

A review of effect on metallurgical properties of friction stir welding using high entropy alloy

The work summarizes the review of use of High Entropy Alloy in the Friction Stir Welding. When High Entropy Alloy is utilized in the Friction Stir Welding the resultant mechanical, metallurgical as well as corrosive properties show the influence of HEA base material properties. The Process used to obtain HEA provides base properties affecting the microstructural impact due to heat generation in FSW. Taking into account HEA, FSW too improve the welding properties of the material. The grain size was affected by heat generation and pressure of rotational as well as transverse speed, and could be differentiated in different zones (SZ, HAZ, and TMAZ) and sides (advancing, retreating, top, and bottom). Results of misorentation, HABs, and LABs were influences by the type of recrystallization. GGAE are associated to HABs and SFE to heating phenomenon, so overall it is HEA reaction to the heat generation in different areas and its effects seen in recrystallization of grains.

Experimental study on the flame height evolution of two adjacent hydrocarbon pool fires under transverse air flow

Hydrocarbon energy storage has a wide range of applications in modern production and life. Regarded as an important form of energy dissipation, combustion plays an important role in energy storage failure. The possible ignition of adjacent leaked fuel might induce multiple fires burning simultaneous. The present work experimentally characterizes the flame evolution of two adjacent pool fires with square and line burners under transverse air flow. As for the effect of transverse air flow, the flame height evolution was recorded and measured involving six different transverse air flow speeds, as the transverse air flow speed increased up to 3 m/s, the flame height gradually decreased. When the transverse air flow increased from 3 to 3.7 m/s, the flame height only changed slightly on both types of burners. A new correlation was proposed that which correlates well the flame height as a function of the ratio of air entrainment caused by transverse air flow to that induced by the flame buoyancy itself in quiescent condition, including the fuel of heptane and ethanol, and the Froude number representing flame tilting caused by transverse air flow. The experimental data and proposed correlations in the present study provide an essential base for quantifying two adjacent pool fires characteristics under transverse air flow.

Friction stir welding process optimization of Al 7075/SiC composites using grey relational analysis

The work presented in this article discusses the optimization of process variables in the friction stir welding of Al 7075/SiC composites using Grey relational analysis (GRA).The aim of the experimental study was to study mechanical properties of friction stir welded joints and to figure out most influencing process variables, their rank on the basis percentage contributions affecting weld characteristics by using GRA. In current experimental work, welding speed (rpm, ω), welding transverse speed (Feed, mm/min, f) and tool pin geometry (τ) were considered as process variables. The response parameters considered were ultimate tensile strength, Vickers micro hardness and percentage elongation (% E),) of friction stir welded joints. The experiments were designed and carried out using Taguchi L9 orthogonal array methodology with three levels of each process variable. The process variables were optimized and ranked on the basis of GRA results. The contribution of each process variable on weld joints was also determined. From optimized process variables obtained through GRA and ANOVA, it was found welding speed (rpm, ω) was the most influencing factor for the current set of process variables with its percentage contribution 50.83 %. The study also shows feasibility of implementing the approach of Taguchi technique and GRA to obtain optimized set of process variable to perform friction stir welding of Aluminium based MMC’s.

Generation of temporal fading envelope sequences for the FSOC channel based on atmospheric turbulence optical parameters.

The temporal characteristics of the free space optical communication (FSOC) turbulence fading channel are essential for analyzing the bit error rate (BER) performances and compiling the rationale of adaptive signal processing algorithms. However, the investigation is still limited since the majority of temporal sequence generation fails to combine the autocorrelation function (ACF) of the FSOC system parameters, and using the simplified formula results in the loss of detailed information for turbulence disturbances. In this paper, considering the ACF of engineering measurable atmospheric parameters, we propose a continuous-time FSOC channel fading sequence generation model that obeys the Gamma-Gamma (G-G) probability density function (PDF). First, under the influence of parameters such as transmission distance, optical wavelength, scintillation index, and atmospheric structural constant, the normalized channel fading models of ACF and PSD are established, and the numerical solution of the time-domain Gaussian correlation sequence is derived. Moreover, the light intensity generation model obeying the time-domain correlation with statistical distribution information is derived after employing the rank mapping, taking into account the association between the G-G PDF parameters and the large and small scales turbulence fading channels. Finally, the Monte Carlo numerical method is used to analyze the performances of the ACF, PDF, and PSD parameters, as well as the temporal characteristics of the generated sequence, and the matching relationships between these parameters and theory, under various turbulence intensities, propagation distances, and transverse wind speeds. Numerical results show that the proposed temporal sequence generation model highly restores the disturbance information in different frequency bands for the turbulence fading channels, and the agreement with the theoretical solution is 0.999. This study presents essential numerical simulation methods for analyzing and evaluating the temporal properties of modulated signals. When sophisticated algorithms are used to handle FSOC signals, our proposed temporal sequence model can provide communication signal experimental sample data generating techniques under various FSOC parameters, which is a crucial theoretical basis for evaluating algorithm performances.

Radio Jet Proper-motion Analysis of Nine Distant Quasars above Redshift 3.5

Up to now, jet kinematic studies of radio quasars have barely reached beyond the redshift range z > 3.5. This significantly limits our knowledge of high-redshift jets, which can provide key information for understanding the jet nature and the growth of black holes in the early universe. In this paper, we selected nine radio-loud quasars at z > 3.5 which display milliarcsecond-scale jet morphology. We provided evidence of the source nature by presenting high-resolution very long baseline interferometry (VLBI) images of the sample at 8.4 GHz frequency and making spectral index maps. We also consider Gaia optical positions that are available for seven out of the nine quasars for better identification of the jet components within the radio structures. We find that six sources can be classified as core–jet blazars. The remaining three objects are more likely young jetted radio sources, compact symmetric objects. By including multiepoch archival VLBI data, we also obtained jet component proper motions of the sample and estimated the jet kinematic and geometric parameters (Doppler factor, Lorentz factor, and viewing angle). Our results show that at z > 3.5, the jet’s apparent transverse speeds do not exceed 20 times the speed of light (c). This is consistent with earlier high-redshift quasar measurements in the literature and the tendency derived from low-redshift blazars that fast jet speeds (>40c) only occur at low redshifts. The results from this paper contribute to the understanding of the cosmological evolution of radio active galactic nuclei.

Dynamic failure of composite strips under reverse ballistic impact

Mesoscale impact experiments on composite strips were conducted in this study to reveal the fundamental failure mechanisms of fiber-reinforced composites (FRCs) under transverse impact by different projectiles. The componential material of composite armor, S-2 glass/SC-15, was manufactured into a single ply and sectioned into strips. The strip specimens were first characterized by X-ray computed tomography and scanning electron microscopy (SEM). The impact experiments were performed using a light-gas gun, shooting the strip specimens to the static wedge-nose projectiles with different nose diameters of 4, 40, and 400 µm. A high-speed camera recorded the strip's failure process from the side. Such a reverse ballistic impact scheme enabled to focus the camera on the projectile nose where the strip was deformed and fractured so that the entire failure process was recorded in real time. These experiments identified three failure modes of the composite strip for each projectile type, defined by no, partial, and complete local failure by the impact loading. The critical velocity region was quantified, showing rising upper and lower boundaries corresponding to the projectile nose diameter. The experimental data were compared with theoretical predictions by Smith's theory. The transverse wave speed deviated from Smith's prediction as the projectile nose diameter decreased, demonstrating a possibly significant error when the pure-tension assumption is employed to model the composite's impact behavior by sharper projectiles. Besides, a sharper projectile was more likely to induce a smaller tent angle, indicating a larger local deformation, considered owing to the stress concentration at the projectile nose.

Process Modelling And Characterisation Of Friction Surface Deposit Of Extruded nickel Aluminum Bronze Over Cast Nickel Aluminum Bronze

ABSTRACTCast Nickel Aluminium bronze widely finds its application in marine components because of ease its of fabrication in complex shapes and geometries. The cast alloys are prone to erosion-corrosion failures in the marine environment. To enhance the corrosion resistance of these alloys, surface modification techniques are being used. Friction surfacing is one such newly developed technique which can be employed to improve the erosion-corrosion resistance of cast NAB alloys. In this investigation an attempt has been made to deposit extruded NAB alloy over cast NAB alloy by friction surfacing technique. The influencing process parameters like plunge rate, rotational speed and transverse speed of tool (extruded NAB alloy rod) were mathematically modelled and empirical relationships were developed using response surface methodology (RSM). These parameters were further optimised using Particle Swarm optimization (PSO) to attain the maximum bonding strength. The Ram tensile strength carried on the surfaced alloy had maximum strength of 245 MPa. The mathematically modelled methods provided results nearing to the experimental values. The values were in good agreement with the experimental values with error deviation of 5%. The erosion corrosion property of the friction surfaced NAB alloy improved than the cast alloy.

Study on the microstructure and properties of WC-12Co cemented carbide fabricated by selective laser melting

In this study, WC-12Co cemented carbides were fabricated by selective laser melting (SLM) and subsequently subjected to sintering. Effects of the scanning speed on the microstructure, mechanical properties and friction and wear performance of the prepared WC-12Co cemented carbides were investigated. Based on the XRD spectra, η phase appeared after the SLM process, confirming a loss of carbon during the preparation of WC-12Co. The WC average grain size increased with improving the scanning speed, which fluctuated in the range of 1.5 μm–2.5 μm. The relatively small WC average grain size was associated with the lamellar structure (alternating layers of coarse and fine WC grains) caused by the uneven temperature distribution of SLM. Co evaporation was quantitatively revealed by EBSD phase maps. Relationships between hardness, transverse rupture strength (TRS) and scanning speeds were analyzed. The comprehensive performance of the samples reached the best at the scanning speed of 400 mm/s, which the hardness, TRS was 81 HRA, and 650 MPa, respectively. Furthermore, after process optimization, the friction and wear properties of the material were tested, the friction coefficient was about 0.2 at room temperature, while 0.5–0.7 at 200°C–600°C.

Influence of reduced graphene oxide addition on kerf width in abrasive water jet machining of nanofiller added epoxy-glass fibre composite.

The present study aims to develop a novel hybrid polymer composite with reduced graphene oxide (rGO) as filler and optimize its Abrasive Water Jet Machining (AWJM) parameters for reduced kerf width. The influence of rGO addition on kerf width is analysed in detail along with Pump pressure (bar), Transverse speed (mm/min) and Standoff distance(mm). The experiments are designed based on Taguchi's orthogonal array techniques in which L27 is adopted for three input parameters at three levels. The influence of each factor is used to identify the significance of selected parameters over kerf width, and it was found that stand of distance has a major effect over kerf width irrespective of rGO %. The addition of rGO filler has a significant effect on kerf width, which decreases with the addition of rGO up to 0.2% and kerf width increases for further addition of rGO.

Investigating local strain rate sensitivity of the individual weld zone in the friction stir welded DP 780 steel

In this study, the effect of variable transverse speed (200 mm/min and 400 mm/min) on the microstructure and mechanical properties of FSWed DP 780 steel was systematically investigated. A detailed microstructural characterization was conducted using OM, SEM and EBSD to reveal the microstructural evolution in specific weld zone and was subsequently explained in context of variable transverse speed. Moreover, nanoindentation-based strain-rate jump tests (SRJT) were implemented to critically investigate the local characteristics with respect to the strain rate sensitivity (m-value) in distinct regions of FSW joint. Indentation hardness contour maps were characterized and analyzed in conjunction with the microstructural observations using EBSD. Refined grain size was observed in the SZ of FSWed-44 sample as compared to FSW-42, which was attributed to the increased dynamic recrystallization. The m-values and local hardness from SRJT for individual weld zones confirmed the rate dependent deformation behavior, which was further explained in conjunction to microstructure-process-property relationship.

Mechanical properties of AA6061T6 and AA6351T6 plates joined by friction stir welding

AbstractIn this study, friction stir welding using a vertical milling machine was performed to join 5 mm thick dissimilar AA6061‐T6 and AA6351‐T6 aluminium alloy plates. The friction stir welding was performed with cylindrical and square pin tools at the tool‘s different rotational and transverse speeds. A dye penetration test (non‐destructive test) was performed to check cracks on welded joints′ surfaces. Tensile strength and hardness were investigated, and microstructure was analyzed. It showed that the welded surfaces were free from any cracks. The maximum ultimate tensile strength of 167.95 MPa was recorded for the square tool pin, while the maximum microhardness was 92 RHN for the cylindrical tool pin. The microstructure analysis of the cross‐section of joints revealed good intermixing of material in the stir zone leading to improved mechanical properties for use in aerospace, automobile, and shipbuilding industries by managing the cost of aluminium welding and increased performance.

Defect monitoring in dissimilar friction stir welding of aluminum alloys using Coupled Eulerian-Lagrangian (CEL) finite element model

ABSTRACTThis article uses coupled Eulerian–Lagrangian finite element algorithm to conduct a three-dimensional thermomechanical study to capture the shape and characteristics of defect type generated while achieving the dissimilar friction stir welding of aluminium alloys. The volume-of-fluid method is used to model the Eulerian region and predict the localised formation of process defects. Three different tool shapes are utilised to achieve the dissimilar friction stir welding joining between AA 2024-T3 on the advancing side and AA 6061-T6 on the retreating side. Process parameter effects such as rotational tool speed, traverse tool speed and tool tilt angle are also investigated. The finite element model results are validated by comparing with the results of a previous experimental study. The results showed the augmentation of the traverse welding speed from 40 to 80 mm/min is a key factor in causing process imperfections such as void and tunnel defects. The lower tilt angle value of 1° resulted in long tunnel defects when high rotational speeds are applied. Also, the combination of high rotational and low transverse speeds promotes the production of a free-defect friction stir welding joint.