Thick Metal Research Articles

Single pass laser vacuum welding of thick steel plates using electromagnetic support

The increasing demand for renewable energy produced by offshore wind turbines goes along with an increased demand in the production of offshore wind turbine foundations, so called “monopiles”, which are made by joining thick metal sheets. The industrial standard of multi-layer submerged arc welding (SAW) for joining of thick metal sheets is the current bottleneck in the production of monopiles. A possible increase in productivity by the implementation of high-power laser welding in a newly developed mobile vacuum chamber (MoVac) and an electromagnetic root support is the subject of this study. Single run butt welds are performed in flat position on S355 mild steel of thicknesses up to 80 mm using a disc laser system with 1030 nm wavelength and a maximum output of 60 kW. The laser optic is fixed on the MoVac-System which is held and manipulated by an articulated robot.

K-X rays induced by helium-like C ions in thick target atoms of different metals

The physical process and experimental phenomena of the interaction between highly charged heavy ions and atoms are very complex, particularly in the intermediate energy region, because of the limitation of accelerator and existing theoretical analysis, less systematic researches, incomplete atomic data, and not so high accuracy. The research of celestial element X-ray data is more scarce and the research of X-ray data of celestial elements is even more scarce. Helium-like C ions with 15–55 MeV kinetic energy provided by the HI-13 MV series accelerator of the China Institute of Atomic Energy are used to bombard Fe, Ni, Nb and Mo thick targets. The HpGe detectors are used to measure the K-X ray emission, and the corresponding K-X ray emission cross sections are obtained. Due to the different ionization degrees of the shell layers of various target atoms, the branching intensity ratio of K<sub><i>β</i> </sub>to K<sub><i>α</i></sub> X rays emitted by Helium-like C ions interacting with Fe and Ni target atoms decreases with the increase of the kinetic energy of the incident ions, while the branching intensity ratio of K-X rays emitted by Nb and Mo target atoms does not change significantly. The K-X ray emission cross section of target atom is calculated by using the formula of thick target cross section, and compared with the results of different theoretical models and proton. The results show that with the increase of the kinetic energy of helium-like C ions, the total emission cross section of the K<sub><i>β</i> </sub>and K<sub><i>α</i></sub> X ray emitted from Fe and Ni target atoms are most consistent with the BEA correction model considering multiple ionization, and the total emission cross section of K<sub><i>β</i> </sub>and K<sub><i>α</i></sub> X ray emitted from Nb and Mo target atoms are closest to the theoretical values of PWBA model. When the energy of proton is the same as that of single nucleon C ion, the cross section of K-X ray produced by proton is about three orders of magnitude smaller than that produced by helium-like C ion.

Efficient, stable, and transparent photovoltaic cells with segment-patterned micro-cavity cathodes

This work presents a micro-cavity cathode as a replacement for the traditional thick metal cathode in natural-color TPVs, improving both aesthetic integration and stability.

EXPERIMENTAL INVESTIGATION AND OPTIMIZATION OF WIRE EDM PROCESS TO CREATE DIFFERENT GEOMETRICAL PROFILES IN METAL MATRIX COMPOSITES

Machining of accurate geometrical profiles like triangles, squares or circles with good surface finish and high productivity in metal matrix composites is required for various industrial applications. Thermoelectic principle-based wire electric discharge machine (WEDM) can be conventionally used to overcome the difficulty which occurs during the machining of composites due to the presence of hard abrasive particles. Therefore, in this investigation, three geometrical profiles possessing equal perimeters were produced in 5 mm thick aluminum metal matrix composites (AMMCs) by WEDM. In order to analyze the effect of reinforcements three different AMMCs containing Al6061 as a matrix were produced by stir casting method. The fabricated composites, respectively, contain 10% alumina ([Formula: see text]), 10% silicon carbide (SiC) and a mixture of 5% [Formula: see text] with 5% SiC. The individual effect of various input parameters like pulse-on time ([Formula: see text] = 30-50 [Formula: see text]s), pulse-off time ([Formula: see text] = 6–12 [Formula: see text]s), current ([Formula: see text] = 1–5 A) and geometrical shapes (circle, triangle, and square) on cutting velocity (CV) and surface roughness (SR) were investigated. Furthermore, parametric analysis using regression models was also performed to evaluate the simultaneous effect of two interacting parameters on CV and SR. The study reveals that in the case of hybrid composite, CV decreases with [Formula: see text] and SR is always higher for triangular profiles when [Formula: see text] and [Formula: see text] change. The regression plots indicate that the interaction effect of [Formula: see text] × [Formula: see text] plays a major role in CV for all three composites. Multiobjective optimization using a composite desirability approach reveals a marginal increase in CV (8.58%) and a significant reduction (57.72%) in SR at optimal input parameters for Al6061–10% SiC. The morphological analysis at optimal input parameters indicates a significant reduction in resolidified metal drops and microcraters.

Mitigating metal artifacts in cone-beam CT images through deep learning techniques

Objective: To develop and evaluate metal artifact removal systems (MARSs) based on deep learning to assess their effectiveness in removing artifacts caused by different thicknesses of metals in cone-beam CT (CBCT) images. Methods: A full-mouth standard model (60 mm×75 mm×110 mm) was three-dimensional (3D) printed using photosensitive resin. The model included a removable and replaceable target tooth position where cobalt-chromium alloy crowns with varying thicknesses were inserted to generate matched CBCT images. The artifacts resulting from cobalt-chromium alloys with different thicknesses were evaluated using the structural similarity index measure (SSIM) and peak signal-to-noise ratio (PSNR). CNN-MARS and U-net-MARS were developed using a convolutional neural network and U-net architecture, respectively. The effectiveness of both MARSs were assessed through visualization and by measuring SSIM and PSNR values. The SSIM and PSNR values were statistically analyzed using one-way analysis of variance (α=0.05). Results: Significant differences were observed in the range of artifacts produced by different thicknesses of cobalt-chromium alloys (all P<0.05), with 1 mm resulting in the least artifacts. The SSIM values for specimens with thicknesses of 1.0 mm, 1.5 mm, and 2.0 mm were 0.916±0.019, 0.873±0.010, and 0.833±0.010, respectively (F=447.89, P<0.001). The corresponding PSNR values were 20.834±1.176, 17.002±0.427, and 14.673±0.429, respectively (F=796.51, P<0.001). After applying CNN-MARS and U-net-MARS to artifact removal, the SSIM and PSNR values significantly increased for images with the same thickness of metal (both P<0.05). When using the CNN-MARS for artifact removal, the SSIM values for 1.0, 1.5 and 2.0 mm were 0.938±0.023, 0.930±0.029, and 0.928±0.020 (F=2.22, P=0.112), while the PSNR values were 30.938±1.495, 30.578±2.154 and 30.553±2.355 (F=0.54, P=0.585). When using the U-net-MARS for artifact removal, the SSIM values for 1.0, 1.5 and 2.0 mm were 0.930±0.024, 0.932±0.017 and 0.930±0.012 (F=0.24, P=0.788), and the PSNR values were 30.291±0.934, 30.351±1.002 and 30.271±1.143 (F=0.07, P=0.929). No significant differences were found in SSIM and PSNR values after artifact removal using CNN-MARS and U-net-MARS for different thicknesses of cobalt-chromium alloys (all P>0.05). Visualization demonstrated a high degree of similarity between the images before and after artifact removal using both MARSs. However, CNN-MARS displayed clearer metal edges and preserved more tissue details when compared with U-net-MARS. Conclusions: Both the CNN-MARS and U-net-MARS models developed in this study effectively remove the metal artifacts and enhance the image quality. CNN-MARS exhibited an advantage in restoring tissue structure information around the artifacts compared to U-net-MARS.

(Invited) Optical Biosensors in Photonic Integrated Circuits for Smart System Integration

Photonic integrated circuits (PIC) are like electronic integrated circuits drivers of communication systems. Moreover, state-of-the-art technologies enable the fabrication of electronic-photonic integrated circuits (ePIC), which allows for example the cointegration of ultra-fast BiCMOS devices with high speed photo detectors. Besides that, this technology provides an attractive platform for biosensors. They open the door for label-free detection of various analytes with high specificity and in real-time. This gives perspective to highly scalable and cost effective technologies for smart system integration of biosensors and electronic readouts to realize a true lab-on-a-chip application.We present the integration of optical biosensors in a Si-based PIC-technology. This comprises a front-end of line with optical waveguides, an integrated Ge-photodiode and a complete back-end of line consisting of three thin and two thick aluminum metal layers. The optical biosensor is integrated by opening the optical waveguide from the backside of the chip. In particular, we released a Si-based slot waveguide, which provides an enhanced evanescent field to interact with the analyte and hence to increase the sensitivity. The slot waveguide is incorporated in a ring resonator and we analyzed the wafer-level performance using the full width at half maximum, which allows us to assess the optical losses. Thermal sensing in a wide temperature range is investigated. In addition, a simple and cost-effective microfluidic is realized and we show initial results of the surface functionalization. Our work demonstrates the compatibility of a photonic biosensor with a photonic integrated circuit technology without any restriction to the standard FEOL and BEOL processing on the wafer front-side, while it keeps the inherent high sensitivity of evanescent-field sensing and opens a route towards smart system integration. Figure 1

Metallic Nanoalloys on Vertical GaAs Nanowires: Growth Mechanisms and Shape Control of Ni-GaAs Compounds.

GaAs nanowires are promising candidates for emerging devices in a broad field of applications (e.g., nanoelectronics, photodetection, or photoconversion). These nanostructures benefit greatly from a vertical integration, as it allows for the exhibition of the entire nanowire surface. However, one of the main challenges related to vertical integration is the conception of an efficient method to create low resistive contacts at nanoscale without degrading the device performance. In this article, we propose a complementary metal-oxide-semiconductor (CMOS)-compatible approach to form alloyed contacts at the extremities of vertical GaAs nanowires. Ni-based and Pd-based alloys on different vertical GaAs nanostructures have been characterized by structural and chemical analyses to identify the phase and to study the growth mechanisms involved at the nanoscale. It is shown that the formation of the Ni3GaAs alloy on top of nanowires following the epitaxial relation Ni3GaAs(0001)∥GaAs(111) leads to a pyramidal shape with four faces. Finally, guidelines are presented to tune the shape of this alloy by varying the initial metal thickness and nanowire diameters. It will facilitate the fabrication of a nanoalloy structure with tailored shape characteristics to precisely align with a designated application.

An investigation on the laser welding process parameter effects on the failure mode of tailor welded blanks during the formability testing

The ability to produce high-quality weld with the least distortion and heat affected zone width by the Nd:YAG laser welding process has made it one of the best candidates for steel tailor welded blanks (TWBs). The effect of process parameters including laser peak power, pulse duration, welding speed, and thickness ratio on the mechanical properties and failure modes of TWBs were investigated. TWBs was made of St12 carbon steel sheets with different thickness of 0.5 mm, 1 mm, and 1.5 mm. The weld zone hardness profile in all samples followed a similar pattern, in that the maximum hardness was in the weld metal and gradually fell throughout the heat affected zone (HAZ) until it reached the hardness of the base metal at the end of the HAZ and the hardness of weld metal increased as the average joint thickness increased. Based on the distribution of hardness in different regions of the weld zone a simple model was proposed for failure mode. Weld metal failure mode (WFM) happened as a result of weld metal thickness reduction caused by incomplete weld penetration or excessive penetration. The heat input per unit volume of weld in thin sheet (Hin) was defined as a criterion that determines failure mode. Therefore, a qualitative criterion was proposed for the prediction of failure mode. Based on this simple model, there is an appropriate limit for Hin for all thickness ratios at which the failure mode is base metal failure mode (BFM). The WMF happens at values lower and higher than this appropriate value range. The experiments approved that BFM and the highest formability and joint strength were obtained when 11J/mm3<Hin<37J/mm3.

CU Wirebond Technology in 16FFC High Performance Automotive Radar Processor with IR Drop Reduction Methodology

High performance automotive radar front-end processors normally use advanced semiconductor packaging such as Flip Chip, fan-in and fan-out wafer level Ball Grid Array (BGA) packages in order to provide superior performance in their applications. However, for a cost effective package in the competitive business market, wirebonded package can also provide similar uncompromised performance. Advanced Cu wirebond technology was evaluated on the 16FFc radar processor. However, the challenge of high voltage drop, also known as IR drop, in 16FFc technology has to be overcome. As wafer technology moves to smaller advanced nodes, the back-end-of-line (BEOL) metal thickness gets thinner, thus increasing the resistance per unit length. Another trend in semiconductor design has been a reduction in operating voltage, meaning that small changes in supply voltage may represent an increasing percentage of the digital swing and potentially lead to incorrect logic values. As current flows through a resistor, the high voltage drop could slow down the circuitry, impact the circuit timing and lead to functional failure. In order to reduce the IR drop in the radar processor when using Cu wirebond, a large quantity of intra-die wires was applied on the 16FFc silicon. IR drop simulation was performed on 3 layout conditions, 0%, 50% and 100% of the intra-die wires. Empirical data was also collected with actual Cu wirebonded samples. The fully populated intra-die wires reduced IR drop by 30%. To enable the reliable performance of the intra-die wires, Stand-off Stitch Bond (SSB) wirebond technology was introduced within the package. The development and reliability evaluation was conducted for Cu wirebonding on 16FFc automotive radar processor of 30mm2 die size in a 14mm x14mm 2-layer substrate BGA package. Wirebond recipe was developed based on detailed Design of Experiment to establish bonding parameters for both standard wires and the intra-die wires. Packages were tested per AEC Grade 1 and AEC Q006 qualifications requirements. All results from package reliability assessments passed with no abnormality. Board level temperature cycling reliability for the BGA package with the four depopulated corner solder balls was evaluated with results surpassing NXP requirement for AEC Grade 1. This paper will present the results and analysis from (1) IR drop simulation and empirical data collection, (2) wirebond development and reliability of standard and intra-die wires on 16FFc Silicon, and (3) board level reliability of a BGA package with four depopulated corner solder balls.

Metal Thickness Measurement System Based on a Double-Coil Eddy-Current Method With Characteristic Ratio Detection

Eddy-current sensor systems have been employed to determine the real-time thickness distribution of metal films and the thickness at endpoint detection in metal chemical mechanical polishing (CMP) processes, to achieve global planarization and avoid over-polishing or under-polishing. However, the large lift-off distance of 3.5 mm between the sensor coil and metal film gradually decreases with continuous wear of the polishing pad, which has a strong negative impact on the sensitivity and accuracy of the thickness measurement. In this study a double-coil eddy-current sensor system, with novel characteristic ratio detection capability, is proposed for metal film thickness measurement and compared with a traditional amplitude-based method. The linear relationship between the characteristic ratio and metal film thickness that is immune to lift-off distance is demonstrated both theoretically and experimentally. The experimental results show that the proposed method performs better than the amplitude-based method, reducing the effect of lift-off distance variation and obtaining an excellent linear measurement range from 24 to 2095 nm. The measurement accuracy is as high as 2.1 nm with an excitation frequency of 1.39 MHz and a large lift-off distance of 3.5 mm. The relative measurement error is less than 1.2% and the endpoint thickness ranges from 100 to 180 nm in the Cu-CMP process, when the lift-off distance varies from 3.6 to 3.3 mm.

Multifunctional Polymer-Metal Lattice Composites via Hybrid Additive Manufacturing Technology.

With increasing interest in the rapid development of lattice structures, hybrid additive manufacturing (HAM) technology has become a competent alternative to traditional solutions such as water jet cutting and investment casting. Herein, a HAM technology that combines vat photopolymerization (VPP) and electroless/electroplating processes is developed for the fabrication of multifunctional polymer-metal lattice composites. A VPP 3D printing process is used to deliver complex lattice frameworks, and afterward, electroless plating is employed to deposit a thin layer of nickel-phosphorus (Ni-P) conductive seed layer. With the subsequent electroplating process, the thickness of the copper layer can reach 40 μm within 1 h and the resistivity is around 1.9×10-8 Ω⋅m, which is quite close to pure copper (1.7 ×10-8 Ω⋅m). The thick metal shell can largely enhance the mechanical performance of lattice structures, including structural strength, ductility, and stiffness, and meanwhile provide current supply capability for electrical applications. With this technology, the frame arms of unmanned aerial vehicles (UAV) are developed to demonstrate the application potential of this HAM technology for fabricating multifunctional polymer-metal lattice composites.

Spin wave dynamics in CoFeB bilayers with wedged Au spacer

This paper presents the experimental studies of ferromagnetic layers separated by a heavy metal wedge. The studied system consists of two thin layers of CoFeB separated by a wedged Au spacer. By performing Brillouin light scattering measurements of the spin-wave dispersion relations, and dependences on the magnetic field, we extract magnetic parameters in the studied ferromagnetic layers as a function of heavy metal thickness. We concluded that for thin ferromagnetic double layers, the magnetic properties strongly depend on the thickness of the wedge gold layer spacer. In particular, the presence of perpendicular magnetic anisotropy diminishes as the thickness of the magnetic material is increased, and at the spacers thicker than 2.5 nm the dynamic coupling between propagating spin waves in both layers is negligible. These findings have potential advantages for the development of future spintronic devices.

High-sensitivity optical fiber SPR sensor with cascaded biconical fiber and hetero-core structure for simultaneous measurement of seawater salinity and temperature

A novel dual-channel optical fiber surface plasmon resonance (SPR) sensor, which achieves high-sensitivity simultaneous measurement of seawater salinity and temperature, was designed and verified. The hetero-core structure based on no-core fiber (NCF) with 40 nm thick Au film and polydimethylsiloxane (PDMS) overlaying was utilized to excite the SPR effect and serve as the temperature sensing channel. In order to effectively separate from the temperature SPR dip, a silver/gold bimetallic film was deposited on the surface of the biconical fiber with a grinding angle of 14° to construct the salinity channel cascaded with the temperature channel, where the metal thickness was determined as Ag/Au: 30 nm/10 nm. The simulation and experimental results showed that the bimetallic film used in this article can significantly improve the figure of merit (FOM) of the sensor compared with the optical fiber SPR sensor deposited with a single kind of metal film. In addition, further experimental results on salinity and temperature indicated that the proposed sensor had a salinity sensitivity of 0.73 nm/‰ and a temperature sensitivity of −2.43 nm/℃, and demonstrated the advantages of ease of manufacturing, acceptable repeatability, and good stability. Therefore, the proposed dual-channel optical fiber SPR sensor has high research value and application prospects in the field of ocean measurement.

Study on forming process of equal wall thickness metal spiral pipe by single screw pump

To solve the problems of poor high temperature resistance of conventional screw pump stator and difficult machining of screw pump stator with equal wall thickness, this paper created a finite element model of equal wall thickness metal spiral pipe for single screw sump with 42CrMo based on tube hydroforming (THF). In this paper, the forming effects of different processes were evaluated by analysing the average pitch, wall thickness thinning rate and inner contour accuracy. Due to the particularity of design section and irregular plastic flow of material, the wall thickness of internal high pressure forming decreases seriously; on the other hand, because the diameter of the designed section is relatively large, the minimum ratio of D2 to Dmin is 1.12, which shows that wrinkles appear in external high pressure forming. As a result, based on the problems of internal and external high pressure forming, a coupling forming process was proposed. The results show that different parameters of coupling forming have little effect on the average pitch of metal spiral tube, and its maximum deviation is 1.08%; while thickness reduction ratio is proportional to initial diameter and thickness. Besides, when the liquid pressure is 350 MPa, the diameter is 60 mm and the wall thickness is 7.5 mm, the contour matching degree is higher; but the material accumulation and wrinkling will happen when the pipe diameter greater than 60 mm.

Combination of a Nondestructive Testing Method with Artificial Neural Network for Determining Thickness of Aluminum Sheets Regardless of Alloy’s Type

Non-destructive and reliable radiation-based gauges have been routinely used in industry to determine the thickness of metal layers. When the material’s composition is understood in advance, only then can the standard radiation thickness meter be relied upon. Errors in thickness measurements are to be expected in settings where the actual composition of the material may deviate significantly from the nominal composition, such as rolled metal manufacturers. In this research, an X-ray-based system is proposed to determine the thickness of an aluminum sheet regardless of its alloy type. In the presented detection system, an X-ray tube with a voltage of 150 kV and two sodium iodide detectors, a transmission detector and a backscattering detector, were used. Between the X-ray tube and the transmission detector, an aluminum plate with different thicknesses, ranging from 2 to 45 mm, and with four alloys named 1050, 3050, 5052, and 6061 were simulated. The MCNP code was used as a very powerful platform in the implementation of radiation-based systems in this research to simulate the detection structure and the spectra recorded using the detectors. From the spectra recorded using two detectors, three features of the total count of both detectors and the maximum value of the transmission detector were extracted. These characteristics were applied to the inputs of an RBF neural network to obtain the relationship between the inputs and the thickness of the aluminum plate. The trained neural network was able to determine the thickness of the aluminum with an MRE of 2.11%. Although the presented methodology is used to determine the thickness of the aluminum plate independent of the type of alloy, it can be used to determine the thickness of other metals as well.

Strength Evaluation of Welded Aluminum T-joints, as a Function of Its Welding Process, Execution, Filler Material, and Weld Root Penetration

Essential requirements for weld seams are the long-term transmission of static and time-varying forces. Requirements for the verification of laser welded fillet weld T-joints are proposed in this paper, since there is no established procedure in this field for laser welding. More precisely, the strength of laser MIG hybrid welded AlMg3Mn T-joints, made from 3.5 mm thick sheet metal are determined, depending on the penetration of their weld root gap. This allowed the unwelded root gap to be related to the decrease in strength, even though this is more apparent with dynamic than with static loading. In addition, the influence of filler material, single and mutual-sided MIG welds have been added to this comparison. Filler materials used are the related AlMg2.7Mn or the extraneous AlSi5.

Scalable Bilayer MoS2‐Based Vertically Inverted p–i–n Light‐Emitting Diodes

AbstractHerein, a vertically inverted p–i–n architecture of light‐emitting diodes (LEDs) is designed for manufacturing feasibility and demonstrated scalable bilayer MoS2‐based LEDs. A 4 inch scale bilayer MoS2 is prepared by a two‐step growth method allocating the pre‐deposition of a few‐nm thick metal film and post‐sulfurization. To apply bilayer MoS2 for an active layer in LEDs, the film is transferred over ZnO nanoparticle layers, an electron transfer layer, and then the rest of the LED components are constructed by thermal deposition. This vertically inverted LED architecture allows individual organic or inorganic components to incorporate without degradation during the wet‐transfer process and transfer electron or hole carriers across separate layers, resulting in efficient radiative recombination in the MoS2 emitting layer. MoS2‐based LEDs exhibit electroluminescence of ≈5.41 cd m−2 throughout four active areas of 6.25 mm2 at a driving voltage of 7 V. Therefore, this achievement can overcome the drawbacks of existing transition metal dichalcogenides (TMDs)‐based optoelectrical applications and extend its potential in various fields, such as flexible, ultrathin, or transparent displays.

Optimization of Laser Direct Structuring Process Parameters for Material Extrusion of Polycarbonate

Laser direct structuring (LDS) is critical in the integration of circuits onto 3D‐shaped plastic parts, such as antennas and radio frequency components. The LDS process encompasses three stages: deposition of 3D parts, laser structuring, and metallization. While laser‐direct structurable parts have been manufactured through plastic injection molding, material extrusion (MEX) is a favored additive manufacturing process for economic low‐volume production and fast prototyping advantages. Although injection‐molded LDS literature is available, 3D‐printed laser‐direct structured components merit further investigation. This study focuses on the MEX of catalyst‐loaded polycarbonate (PC) parts and its LDS process. The parameters from the nanosecond fiber laser, including scan speed, power, and frequency, are thoroughly analyzed to understand the surface property changes and metallization performance of the printed PC parts. The single scan track width, which corresponds to the accuracy of conductive path width and metallization thickness, is employed to elucidate the findings. A process map is built to keep the track width constant aimed at enhancing the uniform metallization of intricate components. Thresholds are established, identifying a minimum track width of 22.1 μm and metallization thickness of 2.5 μm. These delineate clusters of process parameters that yield conductivity levels suitable for various applications.

Plasmon Resonance Properties of Au, Cu and Ag Multi-layered Structures with P(VDF-TrFE)

The theoretical modeling of the optical response of layered metal-polymer structures, which can be employed as plasmonic sensors, is carried out. The calculation of their linearly polarized light reflection is performed with the use of the well-known matrix method, which describes the electromagnetic radiation propagation through a sequence of homogeneous flat-parallel media layers. In this way, the attenuated total reflection curves of the structures containing metal films (Au, Cu, or Ag) and a polymer dielectric are obtained and analyzed. A new sensor is proposed, which will utilize the ferroelectric P(VDF-TrFE) copolymer separating metal films. This might be a perspective idea for the creation of tunable plasmonic sensors. The dependencies of the angular position of a surface plasmon resonance versus the thicknesses of structure’s layers, as well as versus the refractive index of the medium contacting to the free surface of a sensor, are considered. This makes it possible to carry out the approximate search for optimal constructive parameters of a sensor, namely, the thicknesses of metal and polymer layers, and to make conclusion about its resulting sensitivity and working range. It is found that the sensors based on a single metal film and a couple of such films separated by a polymer differ 1 ... 1.3 times in the sensitivity (single metal film demonstrates a more rapid resonant angle shift with analyte refractive index variation). It is established that the employment of Au, Cu, or Ag gives no significant changes in the sensitivity of a two-metal-layer sensor with a polymer, but the widest refractive index registration range may be expected for a Cu-based sensor.

Investigating the effect of input parameters on tool wear in incremental sheet metal forming

Abstract Over the years incremental sheet metal forming (ISMF) has developed as a futuristic technique in which the metal sheets are transformed into the final product with the use of a solid metallic rod having a designed end, rather than a dedicated die. The production lead time is quite high in this process as compared to the conventional sheet forming methods. ISMF is most suitable for developing model for the purpose of research and development, manufacturing of the customized part and for low-volume production. Tool life is an important criterion for determining feasibility of any manufacturing process. The sliding of the forming tool over the clamped metal worksheet during the ISMF is another important aspect for understanding the tool-wearing behaviour. The present study has investigated the wearing of the 440C grade steel forming tool during the ISMF of aluminum grade AA3003-O. It has examined the process statistically to establish that the step downsize (P = 0.021) and sheet metal thickness (P = 0.005) significantly influence the wearing of 440C steel tool. The coefficient of performance, i.e., R 2 has been reported as 92.0 % with an adjusted R 2 of 81.9 %.