Edge Thickness Research Articles

Analysis of effect of bentleg opener geometry on performance in cohesive soil using the discrete element method

Bentleg furrow openers can significantly reduce soil disturbance and reaction forces relative to conventional narrow point openers used in no-tillage farming. The effect of bentleg opener geometry on soil disturbance and reaction forces in a cohesive soil was assessed in a virtual soil bin using the discrete element method. Soil disturbance and reaction forces at an operating depth and a speed of 100 mm and 8 km h −1 , were shown to be minimised by using (1) a shank lateral offset of 70 mm, (2) a side leg bend angle that ensures the elbow, which is the transition between the side leg and vertical shank, is not located below the soil surface, (3) an arched instead of angled elbow, (4) a cutting edge chamfer angle as low as practical, and (5) tine thickness as small as practical. Furrow size was found to be more dependent on shank lateral offset and side leg bend angle than side leg forward angle. Though side leg forward angles >90° reduce particle displacement and will work better in fields with stones and roots, they also considerably increase draught and penetration resistance. A low rake angled foot minimises soil reaction forces and drives soil loosening. Reducing foot height and interaction of the vertical shank with soil particles minimises surface soil displacement. These results have expanded the understanding of bentleg opener mechanics and are in close agreement with those reported for sandy soils. Therefore, similar criteria can be followed to optimise bentleg opener design for different soil types. • Discrete element method predicted bentleg opener geometry effects in Black Vertosol. • Geometries that cause minimum soil disturbance and reaction forces were identified. • Shank lateral offset should be large and arched elbow protrude above soil surface. • Cutting edge chamfer angle and thickness as small as practical are recommended. • Low foot rake angle and foot height reduce soil forces and soil throw, respectively.

Rectangular hollow twisted multi-Gaussian Schell-model source

We obtained a twisted far field with rectangular hollow distribution by designing a new type of light source, which can rotates around the axis during propagation. Then, we derived the expression of cross spectral density function on propagation of such source and analyzed the characteristics of spectral intensity distribution of beam field. In addition, we discussed the influence of corresponding parameters of such a source on the behavior of the beam field, including thickness of the hollow edge, the size of the hollow, and direction of beam rotation in detail.

On the effect of velvet structures on trailing edge noise: experimental investigation and theoretical analysis

This study is inspired by the velvety structures on an owl's upper wing surface. Anechoic wind tunnel experiments were conducted to study the effect of the velvety structures on trailing edge noise as well as the boundary layer flow of a flat plate model. The tests were conducted in The Hong Kong University of Science and Technology low-speed wind tunnel, ultra-quiet noise injection test and evaluation device (UNITED). It was found that the trailing edge noise spectra are significantly modified by the velvety structures. In general, the velvety structures increase the low-frequency noise below a cross-over Strouhal number $St_c$ but reduce the spectral level at higher frequencies. The velvety surface also changes the boundary layer characteristics in terms of the boundary layer thickness, non-dimensional velocity distribution and turbulence distribution. Vortex shedding is suppressed by the velvety coating despite the blunt trailing edge. An analytic model is proposed for the trailing edge noise of a flat plate, including the effect of finite trailing edge thickness and velvety structures on the flat plate surface. The model uses the near wake distribution of the mean and fluctuating velocities in the streamwise direction as the input. The predictions, which require no empirical corrections, match well with the experiments for both the baseline and velvet-coated configurations. With a detailed non-dimensional analysis, this study proposes a potential aeroacoustic function of velvet structures, i.e. noise control through manipulation of boundary layer statistics.

Interactive Focus+Context Rendering for Hexahedral Mesh Inspection.

The visual inspection of a hexahedral mesh with respect to element quality is difficult due to clutter and occlusions that are produced when rendering all element faces or their edges simultaneously. Current approaches overcome this problem by using focus on specific elements that are then rendered opaque, and carving away all elements occluding their view. In this work, we make use of advanced GPU shader functionality to generate a focus+context rendering that highlights the elements in a selected region and simultaneously conveys the global mesh structure and deformation field. To achieve this, we propose a gradual transition from edge-based focus rendering to volumetric context rendering, by combining fragment shader-based edge and face rendering with per-pixel fragment lists. A fragment shader smoothly transitions between wireframe and face-based rendering, including focus-dependent rendering style and depth-dependent edge thickness and halos, and per-pixel fragment lists are used to blend fragments in correct visibility order. To maintain the global mesh structure in the context regions, we propose a new method to construct a sheet-based level-of-detail hierarchy and smoothly blend it with volumetric information. The user guides the exploration process by moving a lens-like hotspot. Since all operations are performed on the GPU, interactive frame rates are achieved even for large meshes.

Optical Lens Edge Detection Method Based Coaxial Alignment Micro Assembly

Optical lens assemblies are key to affecting lens accuracy. The coaxial alignment could improve the accuracy of lens assembly effectively in automatic assembly system. But it was difficult to capture the full edge of the lens in one image because of the limit of the CCD camera field of view and the image edge of the lens is not sharp. The purpose of this paper is to propose an edge detection method of optical lens based on Holistically-Nested Edge Detection (HED) for a micro-assembly system with coaxial alignment function. First, the edge of the optical lens is got by HED method, and then the thick edge of the detected optical lens is refined image and the pixel points in the middle position of the thick edge of the recognized image is extracted. Finally, the least square method is used to fit the edge image of the lens. The results of comparative experimental shows that this method which can extract edge of the optical lens image automatically is more robust and more accurate than the previous edge recognition methods.

Best Architecture of an Artificial Neural Network to Model Prefilming Airblast Atomization: Not So Deep Learning

Abstract A fully connected artificial neural network (ANN) is used to predict the spray characteristics of prefilming airblast atomization. The model is trained from the planar prefilmer experiment from the Ph.D. thesis of Gepperth [Experimentelle Untersuchung des Primärzerfalls an generischen luftgestützten Zerstäubern unter Hochdruckbedingungen, Vol. 75. Logos Verlag Berlin GmbH], in which shadowgraphy images of the liquid breakup at the atomizing edge capture the characteristics of the primary droplets and the ligaments. The quantities extracted from the images are the Sauter Mean Diameter, the mean droplet axial velocity, the mean ligament length, and the mean ligament deformation velocity. These are the prescribed output of the ANN model. In total, the training database contains 322 different operating points at which different prefilmers, liquid types, ambient pressures, film loadings, and gas velocities were investigated. Two types of model input quantities are investigated. First, nine dimensional parameters related to the geometry, the operating conditions, and the properties of the liquid are used as inputs for the model. Second, nine nondimensional groups commonly used for liquid atomization are derived from the first set of inputs. These two types of inputs are compared. The architecture providing the best fitting is determined after testing over 10,000 randomly drawn ANN architectures, with up to 10 layers and up to 128 neurons per layer. The striking results is that for both types of model, the best architectures consist of a shallow net with the hidden layers in the form of a diabolo: three layers with a large number of neurons (≥24) in the first and the last layers, and very few neurons (≈12) in middle layer. This shape recalls the shape of an auto-encoder, where the middle layer would be the feature space of reduced dimensionality. The trend highlighted by our results, to have a limited number of layers, is in contrast with recent observations in deep learning applied to computer vision and speech recognition. It was found that the model with dimensional input quantities always shows a lower test and validation errors than the one with nondimensional input quantities. The best architectures for both types of inputs (dimensional and nondimensional input) were tested versus the experiments. Both provide comparable accuracy, which is better than typical correlations of Sauter mean diameter (SMD) and droplet velocity. As the models take more input parameters into account compared to the correlations, they can predict the experimental data more accurately. Finally, the extrapolation capability of the models was assessed by training them on a confined domain of parameters and testing them outside this domain. It was found that the models can extrapolate at larger gas velocity. With a larger ambient pressure or a lower trailing edge thickness, the accuracy decreases drastically.

Hydrogen-induced marginal growth model for the synthesis of graphene by arc discharge

High-quality graphene is prepared by arc discharge with low cost under hydrogen atmosphere. However, the growth mechanism of graphene synthesis by arc discharge remains unclear. In this paper, the hydrogen-induced marginal growth (HIMG) model is deduced to study the growth mechanism of graphene by combining experiment with numerical simulation results. First, the characteristics of thick edges and thin middle and containing hydrogen are verified by transmission electron microscopy and Raman spectroscopy, respectively. In addition, numerical simulation provides the chemical species and temperature range of graphene growth. Second, the marginal growth pattern of hydrogen transfer and carbon addition is introduced because the C-H and C-C reduce configuration energy and island energy, respectively. Meanwhile, the stacking growth at the margin of the graphene island leads to the longitudinal growth of graphene because of the Van der Waals force and the effect of self-assembly, increasing the number of graphene layers. Finally, graphene sheets with a small amount of hydrogen are deposited on the inner wall after annealing. The investigation of the growth mechanism of graphene under hydrogen atmosphere lays a foundation for the large-scale preparation of graphene by arc discharge.

Implementation of Real-Time Edge Detection Using Canny and Sobel Algorithms

The process of performing tasks related to image processing requires the use of potential techniques such as edge detection. The technique can be used to accomplish tasks related to video and image manipulation. The process of edge detection is very virtual as it acts as the first phase of image analysis and understanding. In this paper, the edges of real-time images were detected for easy extraction of meaningful information from images. A prototype was implemented on OpenCV which is an in-built function cv2. () using python. Canny and Sobel edge detection algorithms are chosen to be used in this paper for comparison purposes to find out which method is better at edge detection. After using both algorithms to detect edges of real-time images, the result showed that the Canny algorithm produced thick edges compared to the Sobel algorithm. The canny algorithm follows the criteria of; Good detection, Good localization, and Minimal response, to output good edge detection results More so, canny uses a double threshold for edge revelation and applies the Gaussian filter which removes of any noise from an image, unlike Sobel which is not resistant to noise. The developed prototype for this study can detect edges of real-time objects without the intervention of any sensor input.

Signal-to-noise ratio optimization in X-ray fluorescence spectrometry for chromium contamination analysis

In most cases, direct X-ray fluorescence (XRF) analysis of solutions entails technical difficulties due to a high X-ray scattering background resulting in a spectrum with a poor signal-to-noise ratio (SNR). Key factors that determine the sensitivity of the method are the energy resolution of the detector and the amount of scattered radiation in the energy range of interest. Limiting the width of the primary spectrum by the use of secondary targets, or filters, can greatly improve the sensitivity for specific portions of the spectrum. This paper demonstrates a potential method for SNR optimization in direct XRF analysis of chromium (Cr) contamination. The suggested method requires minimal sample preparation and achieves higher sensitivity compared to existing direct XRF analysis. Two states of samples, fly ash and leachate from municipal solid waste incineration, were investigated. The effects of filter material, its absorption edge and filter thickness were analyzed using the combination of Monte Carlo N-Particle (MCNP) code and energy-dispersive XRF spectrometry. The applied filter removes primary photons with energies interfering with fluorescence photons from the element of interest, thus results in lower background scattering in the spectrum. The SNR of Cr peak increases with filter thickness and reaches a saturation value when further increased thickness only increases the measurement time. Measurements and simulations show that a Cu filter with a thickness between 100 μm and 140 μm is optimal for detecting Cr by taking into account both the SNR and the exposure time. With direct XRF analysis for solutions, the limit of quantitation (LOQ) of the achieved system was 0.32 mg/L for Cr, which is well below the allowed standard limitation for landfills in Sweden. This work shows that XRF can gain enough sensitivity for direct monitoring to certify that the Cr content in leachate is below environmental limits.

Self-Pillared Ultramicroporous Carbon Nanoplates for Selective Separation of CH4 /N2.

There is growing evidence that pillaring up a densely packed ultramicroporous two-dimensional (2D) structure is an effective strategy to reduce their internal diffusion. Reliable pillaring paradigms, however, is rather challenging. Here we report a one-pot multi-component sequential assembly method for the preparation of a new self-pillared 2D polymer and ultramicroporous carbon with integrated surface protrusions. The molecular level pillaring process is surprisingly fast, that is, in 10 min. The thickness of nanoplate edge and the density (roughness), angle as well as height of protrusions can be precisely tuned. Exemplified in coal bed methane purification/separation, this unique pillared 2D carbons exhibit a CH4 /N2 selectivity up to 24 at a low CH4 partial pressure and two orders of magnitude faster CH4 diffusion kinetics than the commercial carbon molecular sieves. This solution synthesis methodology is generalizable for creation and fine tuning of pillared 2D heterostructures.

Self‐Pillared Ultramicroporous Carbon Nanoplates for Selective Separation of CH4/N2

AbstractThere is growing evidence that pillaring up a densely packed ultramicroporous two‐dimensional (2D) structure is an effective strategy to reduce their internal diffusion. Reliable pillaring paradigms, however, is rather challenging. Here we report a one‐pot multi‐component sequential assembly method for the preparation of a new self‐pillared 2D polymer and ultramicroporous carbon with integrated surface protrusions. The molecular level pillaring process is surprisingly fast, that is, in 10 min. The thickness of nanoplate edge and the density (roughness), angle as well as height of protrusions can be precisely tuned. Exemplified in coal bed methane purification/separation, this unique pillared 2D carbons exhibit a CH4/N2 selectivity up to 24 at a low CH4 partial pressure and two orders of magnitude faster CH4 diffusion kinetics than the commercial carbon molecular sieves. This solution synthesis methodology is generalizable for creation and fine tuning of pillared 2D heterostructures.

Effect on thickness of a single-layer mouthguard of positional relationship between suction port of the vacuum forming device and the model.

Wearing a mouthguard reduces the risk of sport-related injuries, but the thickness has a large effect on its efficacy and safety. The aim of this study was to investigate the effect on the thickness of a single-layer mouthguard of the positional relationship between the suction port of the vacuum forming device and the model. Ethylene-vinyl-acetate sheets of 4.0-mm-thickness and a vacuum forming machine were used. Two hard plaster models were prepared: Model A was 25-mm at the anterior teeth and 20-mm at the molar, and model B was trimmed so the bucco-lingual width was half that of model A. Three model positions on the forming table were examined: (a) P20, where the model anterior rim was located in front of the suction port, (b) P30, where the model anterior rim and front edge of the suction port were close, and (c) P43, where the model anterior rim and palatal rim were located on the suction port. Six mouthguards were fabricated for each condition. Thickness differences due to model form and model position were analyzed. Thickness differences due to model form were observed at the incisal edge and labial surface, and model A was significantly thicker than model B in P43 (P<.01). The thickness of the incisal edge and labial surface was significantly greatest in P43 for model A, but in P30 for model B. The effect of the model position on the forming table on suppressing the labial thickness reduction of the mouthguard depended on the bucco-lingual width of the model. It is important to position the model anterior rim away from the sheet frame if the bucco-lingual width of the model is large and to place the model anterior rim in front of the suction port if the width is small.

Insights into Mechanical and Thermal Properties of Additively Manufactured PLA Samples Triggered by Automotive Industry Demands

Paper explores the influence of the infill density (%), as a process parameter in additive manufacturing (3D printing), upon the mechanical (tensile, impact) and thermo-physical properties of PLA samples. The results indicated degradation of both tensile strengths and moduli with decrease of samples� relative density from 100% to 25% with 49.9% and 42.0%, respectively. Similar behaviour holds on impact strength values that degrades with 56.0% for the samples printed using a 25% infill density. The Young�s modulus variation with relative density values was approximated using a 3rd order polynomial function, in accordance with the expression for closed-cell thick edge rhombus cellular structures. All PLA samples revealed small difference on their coefficients of linear thermal expansion, irrespective of their infill densities, with a decrease of 6.34% in the lowest relative density value specimens, indicating enhanced stability within selected temperature range. Glass transition temperatures were approximately located at 65�C whereas cold-crystallization around 80�C, thus unaffected by selected process parameter.

Effect of Model Height and Model Position on Forming Table on Mouthguard Thickness in Thermoforming Using Circular Frame

Effectiveness and safety of mouthguards are greatly affected by its thickness. The aim of this study was to clarify the effect of model height and model position on the forming table on the mouthguard thickness in thermoforming using a circular frame. Mouthguards were thermoformed using 4.0-mm-thick ethylene-vinyl-acetate sheets and a vacuum forming machine. The sheet was sandwiched between circular frames and fixed to the clamp of the forming machine. Working models were two types of hard gypsum models trimmed so that the height of the anterior part was 25 mm (Model A) and 30 mm (Model B). The model was placed with its anterior rim positioned 40 mm (P40), 30 mm (P30), 20 mm (P20), or 10 mm (P10) from the front of the forming table. Differences in the reduction rate of the thickness due to the model height and model positions were analyzed by two-way ANOVA and Bonferroni’s multiple comparison test. Differences depending on the model height were observed at P40 at the incisal edge and P30, P20, and P10 on the labial surface, and the reduction rate of the thickness was significantly smaller in Model A (P < 0.01). As the distance from the model anterior rim to the front of the forming table was smaller, the rate of the thickness of the incisal edge and the labial surface decreases became larger. The rate of decrease in the thickness of the cusp and buccal surface was the smallest at P20. This study indicated that the difference in the thickness of the single-layer mouthguard depending on the model position on the forming table is affected by the model height. However, that is only the anterior part of the mouthguard, and the difference in thickness reduction rate is less than 5%. Additionally, in order to perform stable forming, it is useful to increase the distance from the model to the frame, and it is important to position the part whose thickness is desired to be maintained in the center of the forming table.

Influence of Trapezoidal Shapes and Cutout Sizes on the Buckling Behaviour of Composite Laminates Under Thermally Induced Loads

Trapezoidal laminated plates with cutouts are commonly found in many engineering field, especially in aerospace structures. In many cases these plates are subjected to various harsh environmental conditions during its service life. Thermally induced load is the one which seriously affect the buckling characteristics of the structural components. The study presents the effect of rise in temperature on the thermal buckling characteristics of trapezoidal laminated composite plates with and without cutouts by using finite element technique. In order to model the plate, a 9-noded heterosis plate element has been used by incorporating the effect of shear deformation. By correlating present findings with the available literature, the effectiveness of the present formulation is verified. The computer program FORTRAN language has been developed to investigate the effect of different parameters such as trapezoidal shapes, cutout offsets, plate aspect ratio, ply-orientations, different thickness and plate edge conditions. The influence of each parameter on the thermal buckling behavior is well investigated through this work.

Reducing Photic Phenomena and Retinal Background Illumination by Using an Intraocular Lens

Background. After implantation of monofocal intraocular lenses (IOLs), the risk of developing light phenomena is 9%, and after implantation of multifocal IOLs the one is 41%. These effects not only cause discomfort, but also poor image quality. The existing IOLs have a number of deficiencies that cause different types of photic phenomena.Objective. The aim of the work is optical calculation and simulation of the parameters that an IOL should have in order to reduce photic phenomena and retinal background illumination while increasing the transmission contrast. We also are aimed to design a new IOL on the basis of the results obtained.Methods. To calculate the reflected rays, we used the Snell–Descartes law, according to which we obtained the value of the critical angle for a hydrophobic acrylic IOL with the refractive index of 1.55 at the wavelength of λ = 0.55 μm. This is consistent with aqueous humor, the refractive index of which is 1.33. The calculation of the transmitted light loss was determined by Fresnel reflection coefficient. We handled with optical system in which the aperture diaphragm fulfilled the role of a pupil. Using the Zemax 13 software environment, we simulated ray path for a human eye, the sagittal axis of which is 28 mm at different height of IOL placement. We applied the results obtained to design a new IOL in the SolidWorks environment.Results. The calculations made it possible to identify the shortcomings of modern IOLs and methods for their elimination. It was found that in order to reduce the risk of photic phenomena and, as a result, of increasing luminous transmission, an IOL should be placed at a distance of at least 4 mm from the iris. It should contain two or more optical layers, the refractive index of which changes towards the center of the lens, and have the surface roughness of 35 nm. Based on the calculations, we carried out simulation in the Zemax 13 environment, which confirmed their veracity. When simulated with these parameters, the standard deviation of an image fell completely within the Airy disk, which has a size of 3.598 μm with an image size of 2.972 μm. Thus, the optical system is considered diffraction limited and no further optical optimizations are possible. Using the Solidworks software and the results obtained, we proposed the proprietary IOL model called "NVision OP". This IOL has an optical part thickness of 1 mm with a diameter of 5 mm. In general, the hollow, volume-replacing IOL with a coating has a diameter of 10 mm and a thickness of 5 mm, the thickness of the coating is 150 μm.Conclusions. The study revealed a number of factors that require improvement and elimination to prevent the occurrence of various types of photic effects. These include: lens surface roughness, IOL refractive power, shape, lens edge thickness, depth of IOL implantation into an eye, phacodonesis and lens displacement, aperture diaphragm diameter. After data optimization, according to the calculated results, we carried out the simulation in the Zemax 13 and Solidworks environments. On the basis of this simulation we proposed the model of an intraocular lens "NVision OP"; the photic effects namely arcs, flare, flashes, glare and halo are eliminated as much as possible. The hollow, volume-replacing IOL "NVision OP" has elements on its coat that allow to use the suture fixation, which prevents the dislocation of the IOL. For the implantation of the proposed IOL "NVision OP", it is recommended to use a viscoelastic and the Alcon injector with the cartridge B. Due to the fact that the shape of the IOL corresponds to the native human lens, the lens is located in the place of the phacoemulsified substance, and the implantation does not take much time.

Tensile behaviour of poly(ether-ether-ketone) (PEEK)/Ni foam co-continuous phase composites

In this work, eight types of poly (ether-ether-ketone) (PEEK)/Ni foam co-continuous phase composites (PEEK–Nis) were fabricated by hot pressing. Unfilled PEEK polymer was also prepared in two different methods: P-1 was prepared by the same method with PEEK–Nis, and P-2 was synthesised via extrusion. The tensile properties and fracture processes of PEEK–Nis were investigated and compared with those of unfilled PEEK polymer. Results showed that the stress–strain curves of PEEK–Nis exhibited elastic deformation, yielding and necking. Nickel foam could improve the tensile toughness and elongation-at-break of PEEK–Nis by increasing the number of edges or decreasing the pore quantities of Ni foam. The Young's moduli of PEEK–Nis were related only to metal content. The Young's moduli of PEEK–Nis increased with Ni volume content, and this relationship showed a secondary upward trend. The fracture surfaces of 10 kinds of materials after tensile tests were observed through scanning electron microscopy. Mirror, mist and hackle zones were found on the fracture surfaces of PEEK–Nis and the unfilled PEEK polymer. Morphological analysis showed that a crack could begin in one site and propagate within the material. However, the Ni prism structure could effectively decelerate crack propagation and even stop the crack, causing the crack to restart in the mirror zone. Two main parameters influence the tensile behaviours of PEEK–Nis including the quantity of Ni edge (or PPI value) and edge thickness. The Ni edge quantity of the foam played a positive role in the tensile behaviour of PEEK–Nis. However the effect of edge thickness has two side effects. In Ni foam, intergranular fracture replaced plastic fracture and degraded tensile performance if edge thickness exceeded 70 μm. Amongst all PEEK–Nis studied in this work, PEEK–NiA-1 exhibits the best performance and its tensile toughness was more than 1.6 times that of P-1.

Implementation of Sobel operator based image edge detection on FPGA

Abstract Image edge detection plays a major role in image processing and computer vision. In an image most important parameter is the edges which are mainly used in image analysis and processing. In Sobel edge detection algorithm hardware implementation is chosen because it can work with less decline in noise at high level. Sobel operator is a derivative mask and it is used for edge detection. Here two different types of edges of an image can be detected. The edge detected image consists of thick boundaries and broken edges. Where the edge detected image cannot obtained completely and the time and space complexity are also high. In order to rectify these drawbacks, the proposed system has the addition of extra masks and also changes the coefficients of each masks in image filter. The proposed system is done by both MATLAB AND SIMULINK for appropriate results. Then the Simulink’s subsystem generates the HDL code to implement in the Xilinx ISE 14.6 software and in FPGA hardware.

Highly Strained Silicon on Polymer Obtained By Temporary Polymer Wafer Bonding

Strain engineering can be called upon to tune the band structures of semiconductors. It is widely used in different types of microelectronics devices and it is expected to enable unprecedented responses in optoelectronics [1]. In the case of single crystal Silicon (sc-Si), several approaches have been proposed, relying either on the lattice mismatch inherent to hetero-epitaxial growth (Si on relaxed SiGe) or on substrate expansion (porous Si) [2, 3]. However, these methods are limited to bi-axial strain and by the maximum strain achievable in sc-Si thin film. We recently evaluated a method enabling to transfer a 200nm thick sc-Si film on a stretchable polymer substrate. Tensile tests proved that applying an external mechanical load on the substrate injected significant amounts of strain into sc-Si [4]. This work is focused on studying different parameters to improve the maximum strain in a Silicon On Polymer (SOP) stack obtained from a 200mm Silicon On Insulator (SOI) wafer using temporary polymer bonding.The overall fabrication process is described in figure 1(a). 2 × 24mm2 rectangles are defined using photolithography in a SOI thin film. The wafer is temporary bonded to a handling silicon substrate with a 40µm thick glue layer. Then, the backside of the SOI is removed with mechanical grinding and selective chemical etching. Finally, the sc-Si thin film is transferred to a 230µm thick flexible substrate thanks to a release layer between the glue and the sc-Si layer. The substrate is cut into tensile test samples as described in figure 1(a).In a previous study we have shown that a 200nm thick sc-Si film could be uniaxialy strained up to 1.5% along the [110] direction [4]. In the present work, we quantify the impact of strain orientation, sc-Si film thickness and pattern edge roughness on maximum uniaxial strain. In order to change the sc-Si film thickness a dry etching step was used after removing the backside of the SOI ubstrate. A soft lithography mask and a standard chrome 1X lithography mask were compared for the fabrication of rectangles. To achieve even smoother pattern edges, TetraMethylAmmonium Hydroxide (TMAH) etching was also used (for 90 minutes in a 25 %wt solution at 80◦C) on a patterned SOI with a silicon oxide layer as a hard mask. Resulting samples were tested on a uniaxial tensile stage coupled to a Raman spectrometer, giving us access simultaneously to the sample macroscopic strain and the silicon local strain.Tensile test results are summarized in figure 1(b). Reducing the thickness of the sc-Si did not improve the strain limit while better edges definitions did. Indeed, using TMAH, uniaxial strains up to 3% along [100] were reached in a 200nm thick sc-Si film on a flexible polymer substrate. These results are highly encouraging for the development of films with a wide range of strain. Furthermore, this method is easily transferable to other materials such as AlN or Ge.

Tool nose radius effects in turning process

The main goal of this article is to study the effects of tool nose radius on some performances in turning process. An analytical approach is developed and adapted for cutting with round inserts or when only the round edge was engaged in the metal. The uncut chip area is evaluated as function to tool nose radius and discretized into some elements which are defined by their average uncut chip thickness and elementary edge direction angle. Cutting edge radius is considered and minimum uncut chip thickness is evaluated for each element. Hence, two mechanisms are studied in relation to the minimum uncut chip thickness: cutting and plowing. Effects of tool nose and cutting edge radii on cutting force components, tool/chip interface temperature, specific cutting energy, tool/chip contact length and chip thickness are investigated. Good agreement was found between experiments and predictive cutting forces when turning stainless steel.