Radius Of Contour Research Articles

Low-frequency band gap design of acoustic metamaterial based on cochlear structure

In this paper, a new chiral spiral structure based on the cochlear structure is proposed. The chiral spiral structure consists of four orthogonally oriented cochlear structures with the same geometric parameters connected at the inner endpoints of the four cochlear structures. Based on the Bloch’s theory and finite element method, the band gap characteristics of the proposed chiral spiral structure are studied. The effects of ligament bending angle (θ), the ratio of arc radius of cochlear contour (α), the ligament thickness (tc ), and the level of the chiral spiral structure (n) on the chiral spiral structure are discussed. The results show that the two-level chiral spiral structure (n= 2) has the best band gap characteristics when θ = 180° and α = 0.45. With the decrease of tc and the increase of n, the opening frequency of the first band gap gradually decreases. When n = 22, the chiral spiral structure has the lowest opening frequency, 1.91 Hz. The existence of the band gap is verified through the low amplitude elastic wave transmission tests. The distribution of the iso-frequency lines indicates that with the increase n, the propagation of elastic waves of the chiral spiral structure shows more distinct directivity, which provides a basis for the propagation control of elastic waves. These findings can provide new design ideas and directions for low-frequency vibration and noise control.

Insights on the J‐integral expression of pure shear carbon black filled natural rubber specimen and predicting the crack growth rate using finite element method

AbstractThe J‐integral approach manifests itself in an efficient way to determine the crack growth and failure mechanism of tread and sidewall compounds used in tyres. Therefore, for a pure shear (PS) specimen of carbon black filled natural rubber, the J‐integral formula was vivisected, and the material parameters were defined using the concepts of solid mechanics considering the planar stress conditions. Theoretical calculations, experimental observations, and finite element analysis were executed to calculate the J value for different strain percentages. Different hyperelastic material models were used to understand the hyperelastic behavior of the test compound, but Yeoh model was found to be the best fit with the least error against the experimental test data. The frequency sweep dynamic mechanical analyzer test was done to observe the viscoelastic response of the material. It was observed that the J value decreased with decreasing contour radius and had exhibited stark difference with the global tearing energy values, indicating the effects of stress softening and the dependence of J value on the elastic characteristics of the material. Further, the J value attained from finite element methods for a random strain 22% was used to predict the crack growth rate of the pre‐notched PS specimen.Highlights J‐integral formula for pure shear specimen using solid mechanics approach. J value comparison of theoretical, experimental, and finite element methods. Dependence of J value on the elastic characteristics of the material. Different hyperelastic models compared and Yeoh model chosen for analysis. Prediction of crack growth rate at a random strain percentage.

Predicting dimensional deviation for sintering-induced shrinkage of Al2O3 ceramics manufactured by vat photopolymerization: Using convolutional neural network

Ceramic additive manufacturing technology facilitates the rapid production of components characterized by intricate geometries. Nevertheless, the dimensional accuracy of ceramic components is often compromised due to anisotropic shrinkage occurring during the sintering process. This study introduces a dimensional deviation model to represent the size variations of cylindrical components after the sintering process. Moreover, the method is expanded to encompass annular components featuring both inner and outer contours, where contour shrinkage is subdivided into self-contour deviation and influenced deviation. Additionally, a convolutional neural network is employed to predict deviations by leveraging a novel learning strategy that utilizes the established dimensional deviation model of solid cylindrical ceramic components to acquire the unknown deviation model of annular component contours. The model has been validated using a solid cylindrical component with a radius of 10 mm, as well as an annular component with an outer contour radius of 9 mm and an inner contour radius of 4.5 mm. The verification results demonstrate that our model achieves accurate predictions of the shrinkage size for these components. The proposed model is expected to replace conventional shrinkage coefficient methods, providing more accurate and reliable predictions for practical applications.

Recognition and Pose Estimation Method for Stacked Sheet Metal Parts

To address issues such as detection failure and the difficulty in locating gripping points caused by the stacked placement of irregular parts in the automated sheet metal production process, a highly robust method for the recognition and pose estimation of parts is proposed. First, a decoding framework for parts of a two-dimensional code is established. The morphological closed operation and topology of contours are used to locate the two-dimensional code, and the type of the part is decoded according to the structure of the two-dimensional code extracted by the projection method. Second, the recognition model of the occluded part type is constructed. The edge information of parts is extracted. The contour convex hull is used to split the part contours, and the similarity of segmented contours is calculated based on the Fourier transform. Finally, the occluded parts are located. The corner points of the metal parts are extracted by the adjacency factor of the differential chain code sequence and the contour radius of curvature. The transformation matrix between the part and the standard template is calculated using similar contour segments and contour corner points. A stereo vision system is built to detect and localize the irregular sheet metal parts for experiments, including detection and information extraction experiments of the two-dimensional laser-generated code and detection and positioning experiments of parts under different occlusion rates. The experimental results show that the decoding framework can accurately decode the two-dimensional code made by a laser under low-contrast conditions, the average recognition rate can reach 93% at multiple occlusion rates, the geometric feature extraction algorithm is more accurate than common algorithms and no pseudo-corner points, the localization error is less than 0.8 mm, and the pose angle error is less than 0.6°. The methods proposed in this paper have high accuracy and robustness.

ИССЛЕДОВАНИЕ ЗАКРИТИЧЕСКИХ ДЕФОРМАЦИЙ ПОЛОГИХ СФЕРИЧЕСКИХ ПАНЕЛЕЙ ПОСТОЯННОЙ ТОЛЩИНЫ

An algorithm for studying the stress-strain state of elastic thin-walled shell systems consisting of shells of revolution has been developed. To solve the nonlinear problem of strong bending of a thin isotropic shell of revolution, in which no restrictions are imposed on the angles of rotation of the normal to the original coordinate surface and the relative linear deformation is small compared to unity, we used the Newton-Kantorovich, which reduces the nonlinear boundary value problem to an iterative sequence of linear boundary value problems. A method was applied to reduce the linear boundary problems to several Cauchy problems, which were integrated numerically using the Runge- Kutta method. To ensure the stability of the solution of stiff Cauchy problems, S.K. Godunov’s method of discrete orthogonalization was applied. Based on this algorithm, a computer program was written to determine the parameters of the stress-strain state of shells with a wide range of changes in geometric, physical, and force parameters and boundary conditions. The stress-strain state of sloping spherical panels of constant thickness with pinching on the outer contour under uniform external pressure has been studied. The process of the formation of loops on the deformation curve depending on the height of the shell has been investigated. Changes in the height of the shell with a constant support contour radius simulates the initial irregularity in its manufacture.

Experimental and Numerical Prediction Model for the Dangerous Radius of Natural Gas Leakage in Soil.

Prediction of the dangerous radius of natural gas plays an important role in reducing the hazards of a buried natural gas pipeline after leakage. The factors affecting the diffusion law of natural gas in soil after leakage are mainly divided into the pipe, soil, and environmental sides. Previous studies focused on the effects of leakage pressure, leakage aperture, and leakage direction on the pipe side and porosity and water content on the soil side. In this paper, experiments and numerical simulations are conducted for further investigating the effects on the diffusion of natural gas in soil of the soil type (porosity and granule diameter) and layered structure among the soil side factors and soil temperature as environmental side factors. The contour radius corresponding to 5% volume concentration (the lower limit of natural gas explosion in soil) is defined as the natural gas dangerous radius for analysis. Based on comprehensive analysis of the effects of the factors, a prediction model is proposed for the dangerous radius of natural gas in soil with leakage pressure, leakage aperture, porosity, and granule diameter as the dominant influencing factors, which is of great significance for locating the source of the leakage.

ABOUT SKIN EFFECTS OF OBLITERATION AND COMPRESSION

There should be factual information on the skin-effect on each well that reduces oil and gas production for operational work, as well as for the calculation of oil and gas deposits or for the design of field development. Well development and operation experience shows that contamination of the bottomhole zone and deterioration of leakage properties may be associated not only with collution, but also with events such as obliteration and rock compaction. Thus, during the operation of wells, events such as shrinkage and retention of microcatches and capillaries in fractured-porous formations over time are inevitable. The impact of this factor must also be taken into account, as the method of impact on the bottomhole zone and the compression of formations under the influence of overburden pressure. Such events should be attributed to the factors that increase the resistance of the bottomhole zone and should be studied as an object of research. The discovery of deep hydrocarbon deposits and their development experience show that failure to take into account the deformation of the porous medium as a result of a drop in formation pressure during development reduces the reliability of development parameters. The commissioning of deeper oil, gas and gas condensate fields requires the interpretation of mining data and the development of methods for hydrodynamic research of wells, taking into account the density of layers. Compression of stratified formations with significant deformation during development and the impact of this effect on the development process significantly improves the theory of filtration, taking into account the compression of formations in gas-hydrodynamic modeling, interpretation of mining data and other issues. In order to study and assess the skin effect associated with obliteration and compression, it is necessary to analyze real well data during the operation of productive oil layers. Three of them used the concepts of "normal" production, productivity, as well as the lowest production and productivity of the oil well in operation, and analyzed the performance of the well for several years. This analysis is based on the fact that production changes from depression to exponential law. The article puts forward a version of the existence of obliteration and compression skin effects along with colmatation in a practical example, and a methodology has been developed and tested to determine them. It has been found that during real depressions for collectors, these skin effects (So-c) may be greater than the colmatation skin effect (Scol). However, in practice, the value of the Scol is not accurately determined by one measurement based on the pressure build-up curve. The skin effect of obliteration and compression (So-c) is simply often negligible. In order to assess the skin-effect of colmotion and obliteration-compression in the reduction of well production, calculations were made at the values of the contour radius Rk = 150 m and well radius rq = 0.1 m. As a result, it was determined that the production of wells can be reduced by 64% due to the obliteration-compression effect. This is about 10 times more than skin effect of colmotation. It was determined that the skin-effect of obliteration and compression had a greater effect on productivity should be taken into consideration when forecasting well production. Keywords: obliteration, skin effect, collector, productivity, production, pressure

ВЛИЯНИЕ ПРОКАТА КОЛЕСА ГРУЗОВОГО ВАГОНА НА КОНТАКТНО-УСТАЛОСТНУЮ ДОЛГОВЕЧНОСТЬ

The authors have analysed and determined curvature and radius of worn contour of a wheel and an inclination angle of a tangent. They have got a dependence of a value of tread surface wear from a mileage. The authors have determined influence of the first-order derivative on curvature radius of the worn contour and refined a formula for that radius. As a result, they have analysed limits of applicability of the formulas that will allow using them in calculations at studying worn tread surface contour.

Numerical Optimization for the Impact Performance of a Rubber Ring Buffer of a Train Coupler

Shock and vibration caused by mechanical motion bring huge potential threats to the service life and assembly reliability of mechanical systems. Rubber materials have been widely used in aircraft, trains, and other engineering fields, due to their excellent properties in shock and vibration absorption. This paper aimed to study the rubber ring buffer applied to a certain type of Chinese locomotive. Firstly, the finite element model was established and verified through experimental data. Based on the verified simulation model, the influence of the constitutive parameters (C01/C10 ratio height H and contour radius R) of the rubber ring on its energy absorption and peak crushing force under impact loading was studied in a numerical environment. Finally, the design of the experiment was carried out by the optimized Latin hypercube method, and the response surface model was established, which intuitively demonstrated the influence of the relevant parameters of the rubber ring on the change trend of the energy absorption and peak force. Based on the proxy model, the parameters that improve the crashworthiness of the rubber ring buffer were found quickly by the NSGA-II optimization algorithm, and the problems of a long calculation time and low optimization efficiency when using the conventional finite element method were avoided. The optimization results stated that when H = 107.57 mm and R = 85.70 mm, C01/C10 = 0.0571 of the energy absorption of the optimized buffer was increased by 59.03%, and the peak force was decreased by 14.37%, compared with the original structure. The optimized rubber ring buffer is expected to reduce the peak crushing force, enhance the energy absorption capacity, and mitigate the damage to the train system caused by shock and vibration.

Numerical Study on Dimensions and Orientation Effect of Semi-Elliptical Cracks in PE100 Pipelines

The through-thickness crack or surface crack in PE100 pipes subjected to internal pressure represents a serious risk to the structural integrity of HDPE pipes, which has attracted wide attention in modern industry. Although experimental research offers reliable predictions of surface crack influence on pipes, the relatively high cost hinders its application. The numerical simulation, as a cost-effective alternative, has been widely applied to assess stress displacement and strain to the entire pipe structure. This is the initial approach adopted in recent decades. This article provides simulations tests of an uncracked pipe and cracked PE100 pipe under different internal pressure values, with varying each time the dimensions of the crack with 1 mm rate for minor and major radius and 0.<i>5mm</i> rates for the largest contour radius, using ANSYS MECHANICAL STRUCTURAL STATIC for simulation.

Primary User Protection Contour and No-Talk Zone Characterization for TV Whitespace Spectrum Reuse in Nigeria.

To encourage secondary spectrum access within the TV broadcast bands in Nigeria, the propagation properties of TV signals on the VHF and UHF frequency ranges were empirically studied through measurements carried from two TV stations. The Pathloss exponent for the VHF band was found to be 1.9 with a characterised Pathloss equation for VHF band computed as 𝑷𝑳 (𝒅𝑩)=𝟖𝟒.𝟎𝟒+𝟏𝟗.𝟎𝟑𝒍𝒐𝒈𝟏𝟎(𝒅), where (𝒅) is the distance from the transmitter to the receiver. The UHF band Pathloss exponent was computed to be 1.8 with a Pathloss equation characterised as 𝑷𝑳 (𝒅𝑩)=𝟓𝟕.𝟑𝟓+𝟏𝟕.𝟗𝟔𝒍𝒐𝒈𝟏𝟎(𝒅). The findings re-echoed the need for specific prediction model to accurately estimate the service coverage of TV stations and facilitate effective utilization of spatial TV white space as it was found that there were divergence in coverage prediction between the measured model and some of the conventional models. Using the protection view point, the protection contour in kilometers for TV signals propagating in the UHF band in Nigeria was characterized to be 𝒅𝒓𝒑= 𝟏𝟎[𝑷𝒕+𝟑𝟐.𝟔𝟓 𝟏𝟕.𝟗𝟔].. Where (𝒅𝒓𝒑) is the protection contour radius modeled as a function of the transmit power of the TV station in decibels with reference to one milliwatt (dBm) for co-channel and adjacent channel coverage. Similarly, the no-talk-zone in kilometers was characterized as a function of the transmit power of the secondary user device in dBm for co-channel usage to be 𝒅(𝒓𝒏−𝒓𝒑)=𝒂𝒏𝒕𝒊𝒍𝒐𝒈[𝑷𝒔−𝟖𝟗.𝟕𝟔𝟏𝟕.𝟗𝟔] modeled as a function of the secondary user transmit power 𝑷𝒔. The separation distance in kilometers from the TV station to the possible secondary user transmitter beyond which no interference exist was computed to have a relationship equal to 𝒂𝒏𝒕𝒊𝒍𝒐𝒈⟦𝑷𝒕+𝑷𝒔−𝟓𝟕.𝟏𝟏𝟏𝟕.𝟗𝟔⟧. This model will facilitate TVWS co-channel coexistence using the specified equation to determine the separation distances between television transmitters and secondary user transmitters.

Magnetized particle motion around magnetized Schwarzschild-MOG black hole

In this paper, we have presented the studies of the motion of magnetized particles and energetic processes around Schwarzschild black holes in modified gravity (MOG). The study of circular stable orbits shows that orbits of magnetized particles can not be stable for the values of magnetic coupling parameter beta ge 1. It was also shown that the range of stable circular orbits increases with the increase of both MOG and magnetic coupling parameters, while the effects of magnetic interaction stronger than the gravity. It was obtained that the increase of the MOG parameter causes the increase of center-of-mass energy collision of magnetized particles. Moreover, we have analyzed how to mimic the magnetic interaction with the spin of Kerr and Schwarzschild-MOG black holes. We have obtained that the magnetic coupling parameter can mimic the spin parameter a le 0.15 (a le 0.28) giving the same radius of innermost contour(co)-rotating orbits at the values of the parameter beta in (-1,1) and the MOG parameter in the range alpha in (-0.17,0.28) while the MOG parameter alpha in (-0.7, 0.9) mimics spin parameter of the black hole with the range |a| in (0,1).

The role of stress softening in crack propagation of filler reinforced elastomers as evaluated by the J-Integral

A recently developed micromechanical model of stress softening and hysteresis of filled rubber is used to calculate the energy density- and stress distribution around the crack tip for a given displacement field, which is determined by digital image correlation. This allows for a quantitative evaluation of stress-softening influences on the J-Integral, J1. In addition, the gradients of stress, strain and energy close to the crack tip are evaluated and compared to predictions of purely elastic material behaviour. The J-Integral is determined for carbon black filled truck tire tread compounds based on natural rubber (NR) and phase separated blends of NR with butadiene rubber (BR) and/or styrene-butadiene rubber (SBR). Dependent on the compound used, J1 is found to decrease significantly with decreasing contour radius r, indicating that most of the energy flux into the crack tip is dissipated due to stress softening and is not available for crack growth. For larger distances r, when the energy field becomes isotropic, plateau values are obtained for the J-Integral, which coincide with global tearing energies calculated by simple thermodynamics.

A novel surrogate to identify anatomical changes during radiotherapy of head and neck cancer patients.

To develop a novel method to monitor external anatomical changes in head and neck cancer patients in order to triage possible adaptive radiotherapy needs. The presented approach aims to provide information on internal anatomical changes based on variations observed in external anatomy. Setup Cone Beam Computed Tomography (CBCT) images are processed to produce an accurate external contour of the patient's skin. After registering the CBCTs to the reference planning CT, the external contours from each CBCT are transferred to the initial - first week - CBCT. Contour radii, defined as the distances between an external contour and the isocenter projection in each CBCT slice, are calculated for each scan over the full 360 degrees. The changes in external anatomy are then quantified by the difference in radial distance between the external contours of any secondary CBCT relative to the initial CBCT. Finally, the radial difference is displayed in cylindrical coordinates as a 2D intensity map to highlight regions of interests with significant changes. Weekly CBCT scans from 15 head and neck patients were retrospectively analyzed to demonstrate the utility of this approach as a proof of principle. External changes suggested by the 2D radial difference map of an example patient after 23 fractions were then correlated with the changes in the gross tumor volumes and organs at risks. The resulting dosimetric effects were evaluated. An interactive standalone software application has been developed to facilitate the generation and the interpretation of the 2D intensity map. The 2D radial difference maps provided qualitative and quantitative information, such as the location and the magnitude of external contour changes and the rate at which these deviations occur. Out of the 15 patients, 10 presented clear evidence of general external volume shrinkage due to weight loss, and nine patients had at least one site of local shrinkage. Only two patients showed no signs of anatomical change during their entire treatment course. For the example patient, the mean (±σ) radial difference was 6.7 (±3.0) mm for the left parotid and 7.3 (±2.5) mm for the right parotid. The mean dose to the left and right parotids increased from 20.1 Gy to 30 Gy and from 16.3 Gy to 29.6 Gy, respectively. This novel method provides an efficient tool to visualize 3D external anatomical changes on a single 2D map. It quickly pinpoints the location of differences in anatomy during the course of radiotherapy, which can help physicians determine if a treatment plan needs to be adapted. The interactive graphic user interface developed in this study will be evaluated in an adaptive radiotherapy workflow for head and neck patients in a future prospective trial.

Identifying Patients with Colon Neoplasias with Gas Discharge Visualization Technique.

To perform an initial assessment of the potential of using the gas discharge visualization (GDV) technique to identify patients with colon neoplasias. The GDV camera (also known as the electrophotonic imaging camera) was used to assess the participants. Colonoscopy was performed on all 78 participants, followed by a GDV scan. The control group consisted of 22 people. An endoscopic examination identified colon tumors in the remaining 56 participants. Participant ages ranged from 45 to 86 years (mean, 64.6 ± 1.2 years). The study analyzed GDV images of each patient's fingers, presenting a whole-body view, as well as separate sectors corresponding to the organs in question. There was a significant number of differences between the control group and the patients with colon tumors. The dynamic of the parameters was examined as the level of tumor dysplasia (neoplasia) varied. The values of the following parameters decreased in the control group as compared to the patients with cancerous polyps: normalized luminescence area, internal noise, contour radius, and average luminescence intensity. The values of the following parameters increased in the control group: radius of the inscribed circle, contour line length, area of luminescence, contour line fractality, contour line entropy, and form coefficients. This pilot study demonstrated a statistical difference between the GDV parameters of patients with colon tumors and the control group. These findings warrant a more in-depth study of the potential for GDV technique in screening programs.

TU-AB-303-02: A Novel Surrogate to Identify Anatomical Changes During Radiotherapy of Head and Neck Cancer Patients

Purpose: To develop a novel method to monitor external anatomical changes in head and neck cancer patients in order to help guide adaptive radiotherapy decisions. Methods: The method, developed in MATLAB, reveals internal anatomical changes based on variations observed in external anatomy. Weekly kV-CBCT scans from 11 Head and neck patients were retrospectively analyzed. The pre-processing step first corrects each CBCT for artifacts and removes pixels from the immobilization mask to produce an accurate external contour of the patient's skin. After registering the CBCTs to the initial planning CT, the external contours from each CBCT (CBCTn) are transferred to the first week — reference — CBCT₁. Contour radii, defined as the distances between an external contour and the central pixel of each CBCT slice, are calculated for each scan at angular increments of 1 degree. The changes in external anatomy are then quantified by the difference in radial distance between the external contours of CBCT1 and CBCTn. The radial difference is finally displayed on a 2D intensity map (angle vs radial distance difference) in order to highlight regions of interests with significant changes. Results: The 2D radial difference maps provided qualitative and quantitative information, such as the location and the magnitude of external contour divergences and the rate at which these deviations occur. With this method, anatomical changes due to tumor volume shrinkage and patient weight loss were clearly identified and could be correlated with the under-dosage of targets or over-dosage of OARs. Conclusion: This novel method provides an efficient tool to visualize 3D external anatomical modification on a single 2D map. It quickly pinpoints the location of differences in anatomy during the course of radiotherapy, which can help determine if a treatment plan needs to be adapted.

Influence of additional tensile force on the stress and deformation of numerically controlled tube bending

According to the working way of the numerically controlled (NC) tube bender and taking the additional tensile force into account, the formulas are derived to calculate the average principal stress in different directions of the bending tube surface, the equivalent stress, the variation of wall thickness, and the ratio of the minor axis to the original radius of outer contour and validated by the experiments. The corresponding experiments and simulation analysis are performed to compare with the calculated results, and it is revealed that the equivalent stress of the bending tube surface is non-uniform and the maximum equivalent stress is localized in smaller deformation field around the bending terminating end. The consideration of the additional tensile force makes the equivalent stress in the outer convex portion of tube remarkably greater than that in the inner concave portion of tube, accelerating the thinning of the tube’s wall and the ovalization of tube’s outer contour. The approximate calculation formulae of additional tensile force is also derived and based on the deformation analysis; the proper adjustment of the additional tensile force could improve the quality of the NC bending tube.

When Metal Meets Ice: Potential for Performance or Injury

Abstract Physical conditioning, technical ability, contact, and protective equipment have been identified through research as factors that can potentially contribute to the incidence of injuries in ice hockey players. One safety-related factor often overlooked is the interaction between the skate blade and the ice. Skating is one of the fundamental skills of a successful hockey player, but the effect of skate sharpening on blade characteristics and performance has received limited research attention. The point of contact with the ice is essentially what allows the transition of human motion to skating mechanics, and it may affect both the quality of skating performance and the potential for on-ice injuries. The purpose of this paper is to address the influence of skate blade sharpening characteristics on performance. Experiments performed to examine skate blade sharpening characteristics have identified radius of hollow (ROH), radius of contour (ROC), pitch and levelness of edges as variables that can be manipulated, quantified, and controlled when analyzing blade-ice interaction and the effect of skate sharpening on skating performance. Optimum values for each may produce more effective skating performances. Less than optimum values can result in slower speeds, longer stopping times, instability, body malalignment, greater fatigue, and potentially, greater chance of injury. Being able to define blade characteristics and determine the best combination of ROH, ROC, and pitch for a specific player allows some degree of control in an environment which can often be unpredictable. Furthermore, although there are standards for acceptable ice in professional hockey leagues, very often players must skate on a surface which is not only less than ideal, but which can also change over the course of a game or practice. Careful sharpening to accommodate for less than ideal ice conditions and the unpredictable nature of the play may also help to prevent fatigue, and injuries.

Experimental investigation of forming defects in flat surface–convex edge hemming

In this paper, flanging and convex edge hemming of aluminum killed draw quality steel was investigated. The investigation was focused on the study of the radius flat hem with an inner sheet. The objective of the study was to determine the influences of the contour radius and flange length on wrinkling, hem-out, roll-in (creep or creepage) and roll-out (growing). A set of complete factorial experiments was designed and conducted in order to determine the effects of the selected experimental parameters. Experimentation provided a design map of failure zones for wrinkling and hem-out as well as fundamental knowledge of important factors in convex edge hemming and factor interactions during different process stages. Results of the experiments were summarized for the use of process and die designers. A future experimental study will focus on pure roll and warp without any wrinkling and hem-out.

Flexible fabrication of microlenses in polymer layers with excimer laser ablation

Abstract Excimer laser ablation is a valuable microfabrication technology, which is particularly well-suited for surface structuring of polymers because of their excellent UV absorption properties and highly non-thermal ablation behavior. In this paper, we propose a fabrication technique for microlenses and arrays of microlenses using this technology and report on the present status of experimental results. The process is based on scanning a polymer surface with a pulsed excimer beam along well-chosen multiple concentric contours and in this way microlenses of arbitrary shape can be realized. Although our current experimental results are limited to structures in polycarbonate, the technique can be applied to any material suitable for excimer ablation of microoptics. The choice of ablation parameters and the selection of contour speeds and radii are discussed. Optical performance and lens surface quality are evaluated by imaging experiments, scanning electron microscopy and profilometer measurements. Due to the non-contact and direct-write nature of laser ablation, the proposed technique offers—contrary to many competing microfabrication processes—the powerful ability to insert microoptical functionality on top of optoelectronic components in a late phase of a heterogeneous assembly.