Papers by Keyword: Wrinkle

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Authors: Li Li, Fei Liu, Jian Li, Yuan Yuan Wang
Abstract: Verisimilitude of 3D face modeling can be strongly enhanced by taking into account skin wrinkles. However, there are two difficulties to model real and natural wrinkles: one is the location of wrinkles and the other is the shape of wrinkles. For the first problem, an algorithm for locating wrinkles through extracting feature curves based on photo is presented; For the second problem, a shape control function is proposed considering the properties of real wrinkles, which could provides intuitive parameters for easily modulating the depth and the width of wrinkles, and express the attenuation and impact of one wrinkle on its surrounding surface. The experiment results by applying the method to a 3D face model show that it not only has the advantage of verisimilitude as the photo, but also has the feature of natural ripple which is deeper and wider in the middle than in both sides.
875
Authors: Takahiro Ohashi, Wan Tong
Abstract: In this study, the authors employ a multi-point die-support structure to hold the upper die for deep drawings in order to adjust the distribution of the blank holding force (BHF) so as to eliminate wrinkles. The developed multi-point support structure has 12 support cells (support units) between the upper die and the outer slide of a double-action press; the cells are metal cylinders working as springs. The support unit has a ball contact at the interface with the upper die, and the interface freely rotates and slides horizontally. The support unit has strain gauges on the side surface, and the bearing load at each unit can be determined, as well as the elastic deformation. The bearing load distribution is observed through a trial blow, and then the support units are manually relocated to better distribute the supporting points to create the appropriate BHF distribution. To demonstrate the efficiency of the suggested structure, the authors perform deep drawing with off-centered setting of a blank to create wrinkles intentionally. They then employ the multi-point die-support system, relocate the support units, and eliminate wrinkles.
1117
Authors: Tomohiro Nonaka, Yutaka Sakata, Yasuo Marumo, Yoshinori Okinishi, Taiki Horinouchi, Ippei Ogawa, Shinobu Watanabe
Abstract: In press working, to prevent defects in sheet products and establish the traceability of the causes of defects, we have developed defect detection dies incorporating several types of sensor, including load sensors, fiber laser sensors, ultrasonic sensors and optional sensors. Typical defects such as the rising of pierced scraps, burrs, spring-back/spring-go and wrinkling can be detected using the defect detection dies, i.e., the intelligent forming dies. The real-time defect inspection of all products will be possible. This system can be used to identify defective products on the basis of sensor information compiled in a database. The causes of defects can be clarified from the situation in real time.
1034
Authors: Xiao Li Zhao, Wei Wei An, Zhan Shan Liu, Hai Chao Yu
Abstract: In this work, the effect of wrinkled microstructures on surface wettbility of ginkgo leaf was investigated. The upper and lower layers of the ginkgo leaf were comparatively measured by Scanning Electron Microscopy (SEM) for contrast of morphological characters. Measurement results show that the upper epidermis is mainly composed of regularly long-rangle stripes of cellular structures with gently smooth cell wall. On the other hand, the lower one is made up of chaotically isolated cellular structures with wrinkled cell wall. The comparative measurement of contact angle (CA) and roll-off angle in the upper and lower epidermis with deionized water was conducted. Wetting behaviors indicate that the lower has stronger hydrophobicity and weaker adhesion than the upper. Through theoretical analysis, the difference in wettability and adhesion was the result of isolated micro-bumps made by hierarchical wrinkles on the lower epidermis, leading to form solid-air-liquid interface between water and wrinkled surface. This research explains the difference of ginkgo leaf in wettability, and has important reference value in the design and preparation of the surface for the biomimetic materials.
1437
Authors: Xiao Li Zhao, Sui Xing Zhang, Wei Wei An, Hai Chao Yu, Zhan Shan Liu
Abstract: Wrinkle evolution under temperature and compression was experimentally explored in a metal film deposited on a compliant polymer. After wrinkle formation, the samples undergo thermal annealing in different temperature circumstances. In the range of 75-150°C, the wavelength and amplitude of wrinkles became both smaller as the temperature increased, indicating that annealing effectively releases residual stress and promote material modification. In contrast, compression only changed wrinkle rearrangement, and did not alter the wavelength and amplitude. These results suggest that external stimulation can transform wrinkled surfaces. This work provides the guidance for service conditions of surface wrinkling.
504
Authors: Zheng Mao Yang, Shashi Bhushan Kumar, Jens P. Tronskar
Abstract: In this paper, FFS assessment procedure for the buckle damaged pipeline with cracks in the girth welds is presented. For FFS assessment the tensile and J R-curve data from a pre-strained pipeline material, API 5L X65 were obtained in the laboratory to study the influences of the large plastic strain on the material properties and the fracture resistance of the pipeline girth welds. Tensile and single edge notch bend specimens in as-received, 10% pre-strained and 20% prestrained conditions were tested. The test results show significant increase in yield and tensile strength in the pre-strained specimens. Generally, the elongation and fracture resistance decreased after pre-straining. In FFS material specific failure assessment diagrams (FADs) generated based on the stress-strain curves obtained from testing were used. The critical flaw sizes of the pipeline girth welds were calculated, and the influence of the large plastic strain on the FFS results was discussed.
173
Authors: W.M. Huang, N. Liu, X. Lan, J.Q. Lin, J.H. Pan, Jin Song Leng, S.J. Phee, H. Fan, Y.J. Liu, T.H. Tong
Abstract: The surface morphology of materials is of fundamental importance to many applications (e.g., surface wetting, friction, surface roughness, reflection, drag, adhesion, etc). Various approaches for micro/nano patterning atop polymer surfaces have been proposed in recent years. However, a cost effective technique is still highly in demand. In this paper, we demonstrate a few novel but rather simple and generic approaches for surface micro/nano patterning using shape memory polymers (SMPs). Reversible micro vertical chains, crown shaped protrusion arrays and strip/labyrinth wrinkles atop SMPs are presented.
243
Authors: Mongkolwongrojn Mongkol, Jeenkour Puttha
Abstract: In web winding process, the effects of speed-up and speed-down on internal stresses of wound roll have been investigated. The air-entrainment can be obtained theoretically using the modified nonlinear Hakiel model. In this research work, air-entrainment model established by Hamrock and Dowson was applied to estimate the initial air film layers into a wound roll in the winding system with a nip-roller. Moreover, the characteristics of a wound roll were examined under varying tension and varying speed conditions. The numerical results showed the radial stress, tangential stress, and friction force distributions at central inside a wound roll under the condition for a wound roll without wrinkle and slippage phenomena.
1262
Authors: Wen Jia Hao, Yu Ming Lu, Chuan Yi Bai, Zhi Yong Liu, Bo Gao, Chuan Bing Cai
Abstract: In the present work, a fast pyrolysis process is developed for YBa2Cu3O7-δ (YBCO) films preparation with trifluroacetates metalorganic deposition technique (TFA-MOD). The decomposition of TFA salts as well as the surface morphology of pyrolyzed films is investigated with respect to the pyrolysis temperature and its heating rate. Two typical surface morphologies for the pyrolyzed films, being smooth or buckled, are revealed subjecting to the heating rate and film thickness, which related to the subsequent YBCO films property. Smooth and wrinkle-free pyrolyzed films are achieved by using this fast pyrolysis process with a heating rate as high as 5°C/min. The final crystallized YBCO films exhibit good performances with the superconducting transition temperature of 91 K and critical current density of 2.0 MA/cm2 at 77 K, suggesting a rapid, promising MOD route available for scale-up preparation of YBCO coated conductors.
267
Authors: Chu Wang, Min Wan, Wen Nan Yuan
Abstract: In this paper, the sheet hydroforming process of 2A12 aluminum alloy with uniform die cavity pressure on to the blank is proposed and investigated both primarily through the finite element method (FEM) and experiments. The influence of the die cavity pressure curve on the quality of the products was explored and the measures to promote the sheet formability were discussed. The results from the studied case indicate that the profile of the cavity pressure was one of the fundamental parameters directly related to the product's quality and precision. Excessive or insufficient initial pressure is not conducive for the reduction of wall thickness thinning and guarantee of wall thickness uniformity. And the wall thickness thinning is reduced and the thickness evenness is improved by increasing the maximum cavity pressure within a proper range. Moreover, an optimum cavity pressure curve generated by the numerical and experimental methods was properly applied in forming the aluminum alloy part without rupture and with slight wrinkle in the flange area. The study demonstrates that the results of simulations based on the identified parameters were in reasonable agreement with those from experiments.
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