Papers by Keyword: Photoelasticity

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Authors: Syuutei Sasaki, Tsutomu Ezumie
Abstract: In modern society, we can see various large structures such as large buildings, ships, bridges that have been constructed using metal, polymers and polymer alloys. Many other new materials are being developed and invented in the world. These materials are made on automatic line systems in factories. These are tested under the rigorous and sever conditions, and shipped on demand. After rigorous testing, however, materials often contain cracks, holes or inclusions. The intensity stress generates on top of the crack and may cause accidents. Holes or inclusions in the material have negative effects on the rigidity and the safety. Many researchers use the high polymer materil for the purpose of the analyzing about cracks, holes and inclusions. The crack, the empty hole and the inclusion become of one of the cause of the fracture and the accident. The authors think that the various problems about cracks, holes and includes are not studied enough. They tried to examine the relation ship of the details of stress intensity factor of the high polymer materials by means of the caustic method and the photoelastic method. This paper discusses the causes and effects of mutual interference of cracks, holes and inclusions in the materials.
Authors: Dong Chul Shin, Byeung Gun Nam, Jeong Hwan Nam, Jai Sug Hawong, Katsuhiko Watanabe
Abstract: In the recent years, the studies on the mechanical behaviors of various materials subjected to biaxial loading have been worked since they are more complicated and intrinsically different from those under the simple uniaxial condition. The cruciform specimen without any slots has been commonly used for the goal so far. We prepare improved biaxial specimen with slots and make sure its validity by means of finite element analysis and photoelastic experiment. Even though the equal load biaxiality was applied to the specimens, as the results, we found that the stress biaxiality ratios in central region of specimen differ according to the position from the center of them, the specimen with slots in the arms is more effective to make state stress uniform than the specimen without slot.
Authors: I.A. Jones, P. Wang, A.A. Becker, Thomas H. Hyde, T.P. Pridmore, A.H. Ghali
Authors: Oskar Ostertag, Eva Ostertagová, Peter Frankovský
Abstract: The aim of the paper is the automation of experimental determination of isotropic and orthotropic background stresses by the tools of the photoelasticity and by the effects of the isolines’ field recorded through the recording medium.
Authors: Hsien Huang P. Wu, Shih Hsin Chang
Abstract: Photoelastic analyses have been successfully conducted by several researchers and many equations based on digital images were presented. Although these equations were all derived using the light intensity emitted from the analyzer, pixel values of the digital image were actually used in the real calculations. In this paper, we proposed that relative light intensity should be used instead for more accurate photoelastic analysis. Real isochromatic images were generated based on relative light intensity as well as pixel value. The analysis showed that the proposed approach can obtain better result than that of the previous method.
Authors: Tae Hyun Baek, Seung Kee Koh, Tae Geun Park
Abstract: hybrid experimental-numerical method is presented for determining the stresses around a circular hole in a finite-width, tensile loaded plate. Calculated fringes obtained by FEA provided the information about the external boundary of the hybrid element, and those fringes on straight lines were used for hybrid analysis. In order to see the effects of varying stress field, different numbers of terms in a power-series representation of the complex type stress function were tested. Actual and reconstructed fringes were compared. The hybrid results were highly comparable with those predicted by FEA. The result showed that this approach is effective and promising because isochromatic data along the straight lines in photoelasticity can be conveniently measured by use of phase shifting photoelasticity.
Authors: Pichet Pinit, Eisaku Umezaki
Abstract: This paper presents an application of a new point-wise technique for unwrapping the isoclinic parameter determined by a four-step color phase shifting. The unwrapping technique is based on a largest region in a binary image that corresponds to a largest visible-wrapped period of the computed isoclinic parameter. The largest region is obtained using an intersection operation between the extended ranges of the computed isoclinic parameter. The method uses four raw photoelastic fringe images. The technique is applied to a circular ring containing isotropic points subjected to diametral compression. Results show the method provides the correct isoclinic parameter in the true interval over the entire domain.
Authors: Digendranath Swain, Jeby Philip, S. Annamala Pillai
Abstract: This paper reports the design assessment carried out on a subassembly of an advanced rocket using experimental techniques. The design was very complex and critical, since a cylindrical shell had a square cutout on the axial-hoop plane interacting with a notch in the axial-radial plane. Herein, two optical techniques have been employed for assessing the interaction between the notch and the cutout, and their individual contributions to the strain-field. Initially, a photoelastic model was studied to estimate the stresses at the notch tip. Subsequently, DIC was employed for measuring strains at the notch during the ground based testing of the actual component. The outcomes of these two experiments showed that the effect of the cutout to the strain concentration was negligible due to the extra stiffness provided by other assemblies.
Authors: O. T. Thomsen, S. Charca
Abstract: Among the different test methods to characterize the fibre/matrix interfacial shear strength, the fragmentation test is one of the most simple in terms of experimental setup and the amount of data that can be extracted from one single test. In this work, the fragmentation test method was implemented to assess the interface shear strength obtained for a single steel filament embedded in an unsaturated polyester resin.. The fragment lengths were discriminated and processed using the Kolmogorov-Smirnov and Chi-square fitting test methods showing that the fragment lengths correspond to the extreme statistical distributions. In addition, a very high shear strength (67MPa) of the steel/polyester interface was estimated using the Kelly and Tyson criteria considering the critical fragment length.
Authors: Jay C. Hanan
Abstract: Efficient manufacturing requires consistency. Automated equipment is designed to accept a small range of input variability and quickly sort and process for next steps. A case study for injection molding of polyethylene terephthalate preforms for use in stretch-blow molding was presented. One convenient method for measuring stresses in optically transparent birefringent parts is photoelasticity. Using cross-polarized light, fringes proportional to the stress state were observed. Faster cooling improved the residual stress state in the injected preforms. The improvements were both in magnitude, as represented by the frequency of fringes and consistency, as represented by the improved symmetry of the fringes. Lower pressure in the mold also aided in improving the residual stress state. Reducing the pressure needed to inject was accomplished by increasing the vent width.
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