Academic literature on the topic 'Rear wall crack'
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Journal articles on the topic "Rear wall crack"
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Zhang, Guojian, Guangli Guo, Chengxin Yu, Long Li, Sai Hu, and Xue Wang. "Monitoring Instantaneous Dynamic Displacements of Masonry Walls in Seismic Oscillation Outdoors by Monocular Digital Photography." Mathematical Problems in Engineering 2018 (August 7, 2018): 1–15. http://dx.doi.org/10.1155/2018/4316087.
Full textAbstract:
Understanding the development of cracks in masonry walls can provide insight into their capability for earthquake resistance. The crack development is characterized by the displacement difference of the adjacent positions on masonry walls. In seismic oscillation, the instantaneous dynamic displacements of multiple positions on masonry walls can warn of crack development and reflect the propagation of the seismic waves. For this reason, we proposed a monocular digital photography technique based on the PST-TBP (photographing scale transformation-time baseline parallax) method to monitor the instantaneous dynamic displacements of a masonry wall in seismic oscillation outdoors. The seismic oscillation was simulated by impacting a suspended steel plate with a hammer and by simulation software ANSYS (analysis system), for comparative analysis. The results show that it is feasible to use a hammer to impact a suspended steel plate to simulate the seismic oscillation as the stress concentration zones of the masonry wall model in ANSYS are consistent with the positions of destruction on the masonry wall, and that the crack development of the masonry wall in the X-direction could be characterized by a sinusoid-like curve, which is consistent with previous studies. The PST-TBP method can improve the measurement accuracy as it corrects the parallax errors caused by the change of intrinsic and extrinsic parameters of a digital camera. South of the test masonry wall, the measurement errors of the PST-TBP method were shown to be 0.83mm and 0.84mm in the X- and Z-directions, respectively, and in the west, the measurement errors in the X- and Z-directions were 0.49mm and 0.44mm, respectively. This study provides a technical basis for monitoring the crack development of the real masonry structures in seismic oscillation outdoors to assess their safety and has significant implications for improving the construction of masonry structures in earthquake-prone areas.
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Fang, Xia, Yang Wang, Yong Li, Jie Wang, and Libin Zhou. "An End-To-End Model for Pipe Crack Three-Dimensional Visualization Based on a Cascade Neural Network." Applied Sciences 10, no. 4 (February 14, 2020): 1290. http://dx.doi.org/10.3390/app10041290.
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With the continuous progress of machine vision technology, crack detection in pipelines has been greatly improved. For crack detection in deep holes, inner tubes, and other environments, it is not only necessary to detect the existence of cracks, but also to collect important information regarding the crack detection direction for further analysis. Because shooting with a frontal field of view causes the real side wall images to produce certain distortions, the detection and calibration of cracks requires a certain amount of professional technology and time. It usually takes a long time to collect the image to eliminate the distortion, and then to identify the crack and mark the direction according to the data line. Therefore, a simple and efficient end-to-end neural network model for crack recognition and three-dimensional visualization are proposed by using a cascade network and simple recognition technology in conjunction with inertial navigation equipment. In addition, we screen the crack data via pixel calibration and eliminate the ambiguous data to make the visualization more accurate. Experiments in pipelines and burrows show that the accuracy, performance, and efficiency of the proposed method reached a high level.
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Wang, Junbo, Weibing Hu, Xinyu Wang, and Yaozhe Liang. "Experimental Investigation of Crack Initiation and Propagation in the Unreinforced Masonry Specimen Subjected to Vertical Settlement." Advances in Materials Science and Engineering 2021 (February 13, 2021): 1–14. http://dx.doi.org/10.1155/2021/6672037.
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To study the cracking process of the wall caused by differential settlement under a uniformly distributed load on the top of the wall, a laboratory model experiment was carried out on large-scale masonry specimens, and the acoustic emission (AE) technique and digital close-range industrial photogrammetry were adopted to monitor the AE signals and displacement characteristics of the masonry specimens during loading in real time. The results show that, in the case of differential settlement with small settlement on both sides and large settlement in the middle, two main cracks appear on the left and right sides of the wall, extending obliquely from bottom to top. During the loading process, damage of the wall is aggravated due to the differential settlement, and both cumulative ringing count and energy count have different periods of steep rise. With the increase in the load and activation of the AE event, the AE event becomes active, and the cumulative ringing count and cumulative energy curve have an obvious turning point, where the slope of the curve is substantially higher than that before the turning point. By using digital close-range industrial photogrammetry, it is observed that the main oblique crack on the left is mainly caused by the difference in the vertical deformation, while the main oblique crack on the right is caused by different displacements and deformation directions of the wall on both sides of the crack.
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Shen, Chao, Chuan Li, Yun Shui Xu, Qing Hua Yan, Shao Quan Zhang, Yan Chen, Xiao Ping Xu, Xiang Chun Xu, and Ying Nan Li. "FBG Displacement Sensor Application Research on Geology Security Monitoring of Substation." Advanced Materials Research 503-504 (April 2012): 1393–96. http://dx.doi.org/10.4028/www.scientific.net/amr.503-504.1393.
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The great area crack can cause the landslide of the substation sliding. Dislocation is the significant factor to reflect the crack. Embedded the mast structure of FBG displacement sensor, the relative displacement of retaining wall in YanJin substation can be obtained. Placed 3 FBG displacement sensors on the southeast corner of the substation downstream integrated the real-time monitoring system for the dislocation crack of YanJin substation downstream. In the monitoring results of the 479 days, daily average displacement of 3# sensor located in substation downstream maximized to 1.58mm on January 27th 2011; and daily average displacement of 2# sensor located in substation downstream minimized to -1.94mm on September 18th 2011. The monthly rainfall maximized to 123.5mm, 70.7mm, 75.9mm in July, August, September 2011 and minimized to 26.8mm, 12.9mm, and 23.3mm in January 2011, November, December 2010. Considered local precipitation, cracks closely related to the local precipitation.
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Hallee, Mitchell J., Rebecca K. Napolitano, Wesley F. Reinhart, and Branko Glisic. "Crack Detection in Images of Masonry Using CNNs." Sensors 21, no. 14 (July 20, 2021): 4929. http://dx.doi.org/10.3390/s21144929.
Full textAbstract:
While there is a significant body of research on crack detection by computer vision methods in concrete and asphalt, less attention has been given to masonry. We train a convolutional neural network (CNN) on images of brick walls built in a laboratory environment and test its ability to detect cracks in images of brick-and-mortar structures both in the laboratory and on real-world images taken from the internet. We also compare the performance of the CNN to a variety of simpler classifiers operating on handcrafted features. We find that the CNN performed better on the domain adaptation from laboratory to real-world images than these simple models. However, we also find that performance is significantly better in performing the reverse domain adaptation task, where the simple classifiers are trained on real-world images and tested on the laboratory images. This work demonstrates the ability to detect cracks in images of masonry using a variety of machine learning methods and provides guidance for improving the reliability of such models when performing domain adaptation for crack detection in masonry.
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Qu, Honglue, Chenxu Wang, Gulan Zhang, Ying Liu, Hao Luo, and Qian Mei. "Seismic damage mechanism of bedrock and overburden layer slope reinforced by sheet pile wall." Journal of Geophysics and Engineering 16, no. 4 (July 15, 2019): 667–79. http://dx.doi.org/10.1093/jge/gxz032.
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Abstract Sheet pile walls, widely used in landslide control projects, have demonstrated excellent seismic performance during the great Wenchuan earthquake, as indicated by an investigation of retaining walls following earthquake damage. To further understand the mechanism of seismic damage based on the Hilbert–Huang transform method and marginal spectrum identification theory, a large-scale shaking table test of bedrock and overburden layer slope reinforced by sheet pile wall was carried out, and the mechanism of seismic damage was analysed. The results show that the change in marginal spectrum amplitude and characteristic frequency can clearly indicate the degree of seismic damage to the slope soil. First, the dynamic response of the slope soil near sheet pile wall is smaller than the response observed in soil farther from the wall, and the degree of seismic damage near the wall is relatively weaker than that farther away from the wall. Second, the energy of the seismic wave cannot be completely transferred behind the wall, and the strip cracks of soil behind the wall can be determined. Finally, the slope soil slides along a slip surface so that the front edge of the slope is squeezed due to the vertical tensile cracks at the rear edge. In addition, the results confirm the feasibility of the Hilbert–Huang transform method for studying the mechanism of the seismic damage to the structure-soil coupling system.
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Zhao, Shun Bo, Fu Lai Qu, Shi Min Zhang, Chang Ming Li, and Peng Bing Hou. "Study on Flexural Resistance of Corroded Reinforced Concrete Walls." Advanced Materials Research 742 (August 2013): 76–79. http://dx.doi.org/10.4028/www.scientific.net/amr.742.76.
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On the requirement of evaluating the bearing capacity of corroded reinforced concrete lock-walls servicing on the Yellow River, the experimental study was conducted to investigate the loading behaviours of normal section of lock-walls, which considered the changes of concrete strength and corrosion level of rebar. The rebar corrosion was accelerated by the mixing of sodium chloride (NaCl) into concrete and the electrolyte corrosion technique in condition of dry-wet curing. The vertical eccentric load was applied on the top of the wall. The results show that some horizontal cracks firstly appeared on the surface of walls during the corrosion period and became wider under the vertical load on the wall. The typical ultimate state was flexural failure. The effects of concrete strength and rebar corrosion level on the resistance of normal section are analyzed based on the test data.
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Chen, Yao, Qian Zhang, Jian Feng, and Zhe Zhang. "Experimental Study on Shear Resistance of Precast RC Shear Walls with Novel Bundled Connections." Journal of Earthquake and Tsunami 13, no. 03n04 (June 2019): 1940002. http://dx.doi.org/10.1142/s1793431119400025.
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This study presents shear resistance of precast reinforced concrete (RC) shear walls. A novel assembling method for upper and lower wall panels is proposed, whereas vertical steel bars are grouped into bundles and effectively connected in preformed holes. To evaluate the feasibility and shear resistance of such a connection method, three specimens of precast shear walls with different horizontal steel bars have been constructed and tested under monotonic loading while subjected to a constant vertical compression. The results show that cracks mainly appear under the line that connects the midpoint of tension side and the corner of the compression side. The weak section of these shear walls is at the top of the preformed holes, and through cracks do not appear at the bottom of walls. These innovative precast shear walls are reliable, and no rebar is pulled out or seriously slipped. The yield load of the shear wall is great, and the stage between yield and failure is satisfactory. The bearing capacity declines slowly after the peak value.
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Zejak, Danijela, Nikolay Vatin, and Vera Murgul. "Analysis of the Masonry Structure Calculation with Vertical Ring Beams According to European Standards." Applied Mechanics and Materials 725-726 (January 2015): 111–17. http://dx.doi.org/10.4028/www.scientific.net/amm.725-726.111.
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Analysis of masonry constructions is done simultaneously by applying the Rules on technical standards for masonry walls (PZZ'81), Regulation on technical standards for the constructions in seismic areas (PIOVS'91) and Eurocodes (EC 6 and EC 8). Eurocode presupposes shear force to be a reliable mechanism form calculating shear wall resistance force, which conflicts to the real behavior of constructions during earthquakes. It is therefore recommended determining the seismic masonry resistance according to the current rules that require verification tensile strain, whose possible exceeding leads to the appearance diagonal wall cracks.
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MATSUI, Akio, Hitoshi KIMURA, Yuki IDOSAKO, Masanori TANI, and Minehiro NISHIYAMA. "CRACK OBSERVATION ON REAL BUILDING REINFORCED CONCRETE WALL WITH DEFORMED BARS AT CRACK CONTROL JOINTS AS CRACK INDUCERS." AIJ Journal of Technology and Design 23, no. 55 (2017): 767–72. http://dx.doi.org/10.3130/aijt.23.767.
Full textDissertations / Theses on the topic "Rear wall crack"
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Šubrt, Stanislav. "Návrh přístroje pro analýzu vzniku a šíření trhlin." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2014. http://www.nusl.cz/ntk/nusl-231511.
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The main goal of this thesis is to get an insight into a field of non-destructive testing using potential drop techniques that have nowadays become the standard not only in the fatigue and loading tests but also in the industry. These methods can serve to non-destructively and continuously measure material specimens, thickness, corrosion losses, deformations, spectroscopy and detection and analysis of crack geometry. They can help to identify materials and measure material changes over time. The second part of this thesis deals with designing the aperture for detection of cracks in steam and product piping using potential drop technique modified by Ing. Ladislav Korec, CSc. Last part deals with extensive testing, experimenting and evaluation of the aperture.
Conference papers on the topic "Rear wall crack"
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Telichev, Igor. "Failure Analysis of Impact Damaged Pressure Vessels and Pipelines." In 2008 7th International Pipeline Conference. ASMEDC, 2008. http://dx.doi.org/10.1115/ipc2008-64332.
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The present paper is devoted to analysis of burst conditions of the pipeline-in-service and vessel under high pressure subjected to the debris impact due to accidental explosion. The central concern of this study is to determine the border between simple perforation and catastrophic fracture of impact damaged pressurized structure. Under certain conditions vessel perforation from the front side can lead to unstable, rapid crack growth (“unzipping”). The pressure vessel of the relatively small size can be damaged from the rear side as well. As a consequence, two main classes of catastrophic failure of such structures are likely to occur: structure fracture from the front side and failure from the rear side. Damage patterns and mechanisms leading to unstable crack growth are discussed. The impact holes in a wall of pressurized structure are considered as a crack-like defect. By the model suggested, the cracked area around the penetrated hole is simulated by two radial cracks emanating from the rim of a hole. So the diameter of the model hole is equal to the diameter of the front impact hole; the length of the crack is bounded by a damage zone, which is a zone of spall cracks adjacent to the perforated hole. In a gas-filled cylinder shell the stresses in the circumferential direction are twice the longitudinal stresses. Thus, in the process of fracturing the cracks tend to run longitudinally, perpendicular to the hoop stress. By this reason the hypothetical radial cracks are normal to the hoop stress. Nonlinear fracture mechanics techniques were used to analyze and predict whether a wall perforation will lead to mere leakage of gas, or whether an unstable crack will run and destroy the pressurized structure. The problem was solved by numerical method of singular integral equations in Chebyshev’s polynomials. A developed model was successfully applied to the simulation of experimental results.
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Zhou, Sheng, Zhengming Zhang, Pierre Lamagnere, Thierry Cadiou, Jean-luc Berton, and Marc Grandotto-Biettoli. "Development of Leak Rate Model for Helium Flow in Elliptically Converging Through Wall Crack." In 18th International Conference on Nuclear Engineering. ASMEDC, 2010. http://dx.doi.org/10.1115/icone18-29814.
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Leak Before Break (LBB) analysis is widely used to demonstrate system safety of pressurized equipments in nuclear plants. Developing a precise leak rate model for helium flow in complex geometry cracks is a key point for LBB analysis in Very High Temperature gas-cooled Reactor (VHTR). A literature study was firstly carried out concentrating on leak rate models proposed or used in LBB analysis. Helium leak rate experiments named DEDIFAR have been performed using elliptically converging and diverging artificial cracks in order to study the effect of the crack length ratio of a real through wall crack. Computational Fluid Dynamics (CFD) calculations of DEDIFAR experiments are presented to analyze the distributions and tendencies of flow parameters in converging cracks. Then, a parametric study was completed to investigate crack geometry effect on mass flow rate. Based on the results of these studies, the effects of upstream pressure and convergence ratio (inside over outside crack lengths) on mass flow rate are analyzed. The results show that the pressure loss mainly concentrates around the smallest exit crack area, and that when the convergence ratio equals or exceeds 20, flow parameters inside the crack domain remain almost the same.
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Schmid, Stefan, Rudi Kulenovic, and Eckart Laurien. "Leakage Flow Investigations on a Through-Wall Crack Related to Thermal Fatigue of Nuclear Power Plant Piping." In 2017 25th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/icone25-67188.
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For the validation of empirical models to calculate leakage flow rates in through-wall cracks of piping, reliable experimental data are essential. In this context, the Leakage Flow (LF) test rig was built up at the IKE for measurements of leakage flow rates with reduced pressure (maximum 1 MPA) and temperature (maximum 170 °C) compared to real plant conditions. The design of the test rig enables experimental investigations of through-wall cracks with different geometries and orientations by means of circular blank sheets with integrated cracks which are installed in the tubular test section of the test rig. In the paper, the experimental LF set-up and used measurement techniques are explained in detail. Furthermore, first leakage flow measurement results for one through-wall crack geometry and different imposed fluid pressures at ambient temperature conditions are presented and discussed. As an additional aspect the experimental data are used for the determination of the flow resistance of the investigated leak channel. Finally, the experimental results are compared with numerical results of WinLeck calculations to prove specifically in WinLeck implemented numerical models.
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Kang, Yong-Seok, Hong-Deok Kim, Kuk-Hee Lee, and Jai-Hak Park. "Evaluation of Interaction Effects on Part-Through Cracks in Steam Generator Tubes." In 2013 21st International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/icone21-15429.
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Degraded steam generator tubing can affect its safety functions. Therefore, its integrity should be maintained for each degradation form and all detected degradation must be assessed to verify that if adequate integrity is retained. Determination of tube integrity limits includes identifying acceptable structural parameters such as flaw length, depth, and amplitude of signals. If we consider just single-cracked tubes, short and deep flaws are not likely to threaten structural integrity of tubes. But if it has multiple-cracks, we have to consider interaction effects of multiple adjacent cracks on its burst pressure. Because adjacent multiple cracks can be merged due to the crack growth then it can challenge against the structural performance limit. There are some studies on the interaction effects of adjacent cracks. However, existing works on the interaction effect consider only through-wall cracks. No study has been carried out on the interaction effects of part-through cracks. Most cracks existing in real steam generator tubing are not through-wall cracks but part-through cracks. Hence, integrity of part-through cracks is more practical issue than that of through-wall cracks. This paper presents experimental burst test results with steam generator tubing for evaluation of interaction effects with axial oriented two collinear and parallel part-through cracks. The interaction effect between two adjacent cracks disappeared when the distance exceeds about 2 mm.
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Sakai, Michiya, Shinichi Matsuura, and Fumio Inada. "Hybrid Seismic Response Evaluation Method for Wall Thinning Piping System." In 2013 21st International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/icone21-16716.
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Pipe wall thinning is a one of the major degradation mechanisms in aged nuclear power plants (NPPs). In Japan, the seismic safety of wall thinning piping system during earthquake must be evaluated in aged NPPs. Seismic safety of piping systems with wall thinning had been investigated by other researchers using shaking table tests of reduced scale and numerical analyses. However, there exist the limitations such as the scale effect of pipe model for shaking table tests and the limit of the evaluation for numerical analysis concerning the criteria of pipe integrity. By the way, elbow can be one of the most important elements to evaluate the seismic safety of piping system. So, in order to evaluate seismic safety of piping systems with wall thinning elbow, hybrid tests have been conducted, in which the seismic response of the whole piping system is treated as a numerical model, and the real piping is used only for the element on which the transformation and damage locally concentrated. The through-wall crack only occurred in the case of a uniform thinning model although cracks didn’t penetrate in the non thinning model and the local thinning model. In the experimental condition, the failure mode of wall thinning elbow under seismic loadings had been low cycle fatigue, and effectiveness of this evaluation method has been demonstrated.
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Levy, C., M. Perl, and S. Kotagiri. "The Influence of the Bauschinger Effect on the Combined Stress Intensity Factors of Multiple Longitudinally Coplanar Cracks in Autofrettaged Pressurized Cylinders." In ASME 2006 Pressure Vessels and Piping/ICPVT-11 Conference. ASMEDC, 2006. http://dx.doi.org/10.1115/pvp2006-icpvt-11-93037.
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The influence of the Bauschinger Effect (BE) on the three dimensional, Mode I, Combined Stress Intensity Factor (SIF) distributions for arrays of longitudinal coplanar, surface cracks emanating from the bore of a fully or partially autofrettaged thick-walled cylinder is investigated. The combined SIFs, KIN, that depend on both the “realistic” - Bauschinger Effect Dependent Autofrettage (BEDA) and “ideal” - Bauschinger Effect Independent Autofrettage (BEIA) are obtained and compared for crack to wall thickness, a/t = 0.01–0.25; crack ellipticity, a/c = 0.5–1.5; crack spacing ratio, 2c/d = 0.25–0.75; and autofrettage level, e = 30, 60 and 100%. The 3-D analysis is performed via the finite element (FE) method and the submodeling technique, employing singular elements along the crack front. Both autofrettage residual stress fields, BEDA and BEIA, are simulated using an equivalent temperature field. The KIN is found to vary along the crack front with the maximum determined by the crack ellipticity, crack depth and crack spacing ratio. For a partially autofrettaged cylinder, the influence of the BE on the combined SIF, KIN, is considerably reduced as the level of overstrain becomes smaller. For some cases, when comparing like crack distributions, the KIN values obtained from the BEDA model are found to be as much as 100% higher than the KIN values that are computed using the BEIA model. A pressurized thick-walled cylinder with BEDA can be most dangerous when small cracks have small spacing ratio, i.e., when the cracks are farther apart. As crack length increases, or, for increased spacing ratio when the spacing between cracks is smaller, the SIFs increase. Though the differences in the BEDA SIF, KIA, between e = 100% and 60% are small (7–15%, in most cases), the increased level of autofrettage produces a 23–30% decrease in the combined SIF values, KIN. In certain cases, the BEIA model implies an infinite fatigue life, whereas the BEDA model for the same parameters implies a finite life. Therefore, it is important to perform a full 3-D analysis to determine the real life cycle of the pressurized cylinder for materials that exhibit the Bauschinger effect.
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Kim, Jin-Weon, Yeon-Soo Na, Sung-Ho Lee, and Chi-Yong Park. "Evaluation of Failure Pressure of Locally Wall-Thinned Elbow by Real-Scale Pipe Tests." In ASME 2007 Pressure Vessels and Piping Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/pvp2007-26445.
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This study performed a series of burst tests using real-scale pipe elbows containing simulated wall-thinning defect, to evaluate the effects of local wall-thinning on the failure pressure of pipe elbows. The tests were conducted under simple internal pressure at room temperature. In the tests, various wall-thinning geometries, such as thinning depth, length, and circumferential angle, and thinning locations, extrados and intrados, were considered. From the results of tests, the effects of thinning geometries and locations on the failure pressure of local wall-thinned elbows were investigated. The dependences of failure pressure on the thinning length and depth in the wall-thinned elbow were similar to those in the wall-thinned straight pipe. The failure pressure clearly decreased with increasing circumferential thinning angle, which was different from the results of wall-thinned straight pipe. Also, the failure pressures were compared with the results predicted by existing evaluation models. The existing models showed excessive conservatism. For intrados wall-thinning case, especially, the conservatism was significant and the variation in failure pressure with thinning geometries could not be properly predicted. For extrados wall-thinning case, the existing models appropriately estimated the dependence of failure pressure on the thinning length and depth. All specimens tested were failed by bulging followed by axial cracking. For extrados and intrados wall-thinned elbows, the crack always occurred at the minimum wall-thinned area. For entire circumferential wall-thinned elbow, however, the crack location depended on the axial thinning length.
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Bae, Kyung-Dong, Ho-Wan Ryu, Seung-Jae Kim, Hyun-Suk Nam, and Yun-Jae Kim. "Assessment Method for Complex Cracked Pipe Using Equivalent Pipe Concept." In ASME 2016 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/pvp2016-63427.
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This paper proposes the assessment method of complex cracked pipes. Complex crack is the form of crack existing through-wall crack and surface crack at the same time [1–2]. Complex crack is mainly caused by PWSCC phenomenon in pipe with overlay maintenance welding. At first, circumferential surface crack is developed by PWSCC phenomenon in the weakest point which is nickel alloy welding point. And this crack propagates to axisymmetric crack in inner surface. After that the crack initiates in not only pipe part but also overlay maintenance welding part, complex crack shape which is main subject in this paper is formed. Unlike through-wall cracked pipes or surface cracked pipes, complex cracked pipes have a complex behavior because of combining through-wall crack behaviors and surface crack behaviors in cracked part. So calculating J-integral and defining amount of crack growth of complex cracked pipes are more difficult than those of through-wall cracked pipes and surface cracked pipes. Therefore, in this paper, the concept using equivalent pipe is proposed for assessment method of complex cracked pipes. To determine equivalent pipe, maximum loads of various through-wall cracked pipes having same circumferential crack size and different thickness are calculated. The reason why through-wall cracked pipe is selected for equivalent pipe is that many researches about J-integral and crack growth of through-wall cracked pipes are already performed and those results are sufficiently validated. In addition, it can be not only directly utilized procedure of leak before break assessment but also compared previous research results using only through-wall cracked part in complex cracked pipes referred to reduced thickness method. Maximum loads of complex cracked pipes and through-wall cracked pipes are calculated using stress-modified fracture strain model in finite element analysis [3–6]. This model is technics removing load bearing capacity in elements which satisfy damage criteria. Damage criteria is determined by using tensile experiment results, fracture toughness experiment results and validated by comparing with real size pipe experiment results. All the experiment results are in pipe fracture encyclopedia published by Battelle [7]. The experiments utilized in the paper are performed in operating temperature 288°C and materials of pipes are stainless steel SA376 TP304 and carbon steel A106 Gr.B. Finally, the results of equivalent through-wall cracked pipe thickness are provided.
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Lee, Tae-Rin, Yoon-Suk Chang, Jae-Boong Choi, and Young-Jin Kim. "Assessment of Ductile Crack Growth Based on a Local Approach." In ASME 2006 Pressure Vessels and Piping/ICPVT-11 Conference. ASMEDC, 2006. http://dx.doi.org/10.1115/pvp2006-icpvt-11-93439.
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The influence of stress triaxiality was a matter of concern on ductile fracture to explain geometry dependent fracture resistance characteristics of specimens and real structures during past two decades. Regarding the issue, recently, interests for local approach and micro-mechanical damage models are increased again in accordance with progress of computational environments. In this paper, the applicability of a local approach is investigated through a series of finite element (FE) analyses incorporating both a modified GTN model and a Rousselier model as well as fracture toughness tests. The ductile crack growth behaviour of SA515 Gr.60 carbon steel is assessed to guarantee transferability of fracture resistance curve from typical specimens with different in-plane and out-of-plane sizes. The material parameters are determined by calibration of test results and corresponding numerical analyses results, and used to simulate the fracture behaviour of CT specimens. Then, a comparison is drawn between the numerically estimated crack resistance curves and experimentally determined ones. Finally, the Rousselier model is applied to estimate J-R curves of circumferential through-wall cracked pipe. The comparison results showed that the two damage models can be used as promising solutions for ductile crack growth simulation.
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Zhao, Xuefeng, Niannian Wang, Linan Wang, Yan Yu, Mingchu Li, and Jinping Ou. "Public Participatory Integrity Monitoring of the Great Wall Based on Smart Phones." In ASME 2016 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/smasis2016-9065.
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Some of The Great Wall relics are destroyed or even disappeared. The existing studies relied on field surveys are costly and time consuming. So a new cloud monitoring system based on smart phones is proposed. The system, which consists of three modules, image acquisition, questionnaire and real-time location, can realize rapid acquisition of information. Firstly, using smart phones, some photos of the Great Wall can be obtained. Then, the typical integrity damage information and location information can be obtained, including structure crack, human-caused destruction, the vegetation growth, etc. Secondly, analyzing the typical integrity damage information, the evaluation results are obtained. Then, the Great Wall information in the form of questionnaire is posted on the Great Wall integrity monitoring system. Mobile phone users who logged in the system can upload photos, and fill in the questionnaires. Through taking pictures and filling in the questionnaires, the required information can be obtained.