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Relevant bibliographies by topics / Crack models

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Academic literature on the topic 'Crack models'

Author: Grafiati

Published: 4 June 2021

Last updated: 2 February 2022

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Journal articles on the topic "Crack models"

1

Mohammed, Mohammed Ameen, Zheng Han, and Yange Li. "Exploring the Detection Accuracy of Concrete Cracks Using Various CNN Models." Advances in Materials Science and Engineering 2021 (September 9, 2021): 1–11. http://dx.doi.org/10.1155/2021/9923704.

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Automatic crack detection with the least amount of workforce has become a crucial task in the inspection and evaluation of the performances of concrete structure in civil engineering. Recently, although many concrete crack detection models based on convolutional neural networks (CNNs) have been developed, the accuracy of the proposed models varies. Up-to-date, the issue regarding the convolutional neural network architecture with best performance for detecting concrete cracks is still debated in many previous studies. In this paper, we choose three established open-source CNN models (Model1, Model2, and Model3) which have been well-illustrated and verified in previous studies and test them for the purpose of crack detection of concrete structures. The chosen three models are trained using a concrete crack dataset containing 40,000 images those with 227 × 227-pixel in size. The performance of three different convolutional neural network (CNN) models was then evaluated. The comprehensive comparison result indicates that Model2 which used batch normalization is capable of the best performance amongst the three models as selected for concrete cracks detection, with recording the highest classification accuracy and low loss. In a conclusion, we recommend Model2 for a concrete crack detection task.

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Hu, Guo X., Bao L. Hu, Zhong Yang, Li Huang, and Ping Li. "Pavement Crack Detection Method Based on Deep Learning Models." Wireless Communications and Mobile Computing 2021 (May 15, 2021): 1–13. http://dx.doi.org/10.1155/2021/5573590.

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Severe weather and long-term driving of vehicles lead to various cracks on asphalt pavement. If these cracks cannot be found and repaired in time, it will have a negative impact on the safe driving of vehicles. Traditional artificial detection has some problems, such as low efficiency and missing detection. The detection model based on machine learning needs artificial design of pavement crack characteristics. According to the pavement distress identification manual proposed by the Federal Highway Administration (FHWA), these categories have three different types of cracks, such as fatigue, longitudinal crack, and transverse cracks. In the face of many types of pavement cracks, it is difficult to design a general feature extraction model to extract pavement crack features, which leads to the poor effect of the automatic detection model based on machine learning. Object detection based on the deep learning model has achieved good results in many fields. As a result, those models have become possible for pavement crack detection. This paper discusses the latest YOLOv5 series detection model for pavement crack detection and is to find out an effective training and detection method. Firstly, the 3001 asphalt crack pavement images with the original size of 2976 × 3978 pixels are collected using a digital camera and are randomly divided into three types according to the severity levels of low, medium, and high. Then, for the dataset of crack pavement, YOLOv5 series models are used for training and testing. The experimental results show that the detection accuracy of the YOLOv5l model is the highest, reaching 88.1%, and the detection time of the YOLOv5s model is the shortest, only 11.1 ms for each image.

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Burchill, Madeleine, Simon Barter, Lok Hin Chan, and Michael Jones. "Microstructurally small fatigue crack growth rates in aluminium alloys for developing improved predictive models." MATEC Web of Conferences 165 (2018): 13004. http://dx.doi.org/10.1051/matecconf/201816513004.

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The fatigue or durability life of a few critical structural metallic components often sets the safe and/or economic useful life of a military airframe. In the case of aluminium airframe components, growth rates, at or soon after fatigue crack nucleation are being driven by near threshold local cyclic stress intensities and thus are very low. Standard crack growth rate data is usually generated from large cracks, and therefore do not represent the growth of small cracks (typically <1mm). Discussed here is an innovative test and analysis technique to measure the growth rates of small cracks growing as the result of stress intensities just above the cyclic growth threshold. Using post-test quantitative fractographic examination of fatigue crack surfaces from a series of 7XXX test coupons, crack growth rates and observations of related growth phenomenon in the threshold region have been made. To better predict small crack growth rates under a range of aircraft loading spectra a method by which standard material data models could be adapted is proposed. Early results suggest that for small cracks this method could be useful in informing engineers on the relative severity of various spectra and leading to more accurate predictions of small crack growth rates which can dominate the fatigue life of airframe components.

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Cui, Jin, and Le Le Zhang. "Shakedown and Limit Analysis of Crack Structure Based on Simple Models." Advanced Materials Research 487 (March 2012): 216–20. http://dx.doi.org/10.4028/www.scientific.net/amr.487.216.

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For the loading capability of structures with cracks, the simply calculational models of structures with triangular and rectangular crack have been established, under considering the local rounded area of the crack tip in this paper. The calculation of limit/shakedown domains has been successfully done based on the method of interior point. The influence of some factors such as crack shape and tip size on the loading limit and shakedown of structure has been analyzed and compared, and the results are the trial foundation of intensive study about crack structures.

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De Iorio, Antonio, Marzio Grasso, George Kotsikos, F. Penta, and G. P. Pucillo. "Development of Predictive Models for Fatigue Crack Growth in Rails." Key Engineering Materials 488-489 (September 2011): 13–16. http://dx.doi.org/10.4028/www.scientific.net/kem.488-489.13.

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Fatigue failures of rails often occur at the rail foot, since the geometry of this zone gives rise to stress concentrations under service loads or defects during rail manufacture and installation. In this paper, the fatigue behavior of cracks at the web/foot region of a rail is analyzed numerically. Analytical models in the literature for a semi-elliptical surface crack in a finite plate assume that the geometry of the front remains semi-elliptical during the whole propagation phase and the ellipse axes do not undergo translations or rotations. Fatigue tests show that this is not the case for such cracks in rails. A predictive model for crack growth has been developed by assuming an initial small crack at one probable initiation point between the web and foot of the rail in reference to a service condition loading. SIF values have been estimated by means of the finite element method and the plastic radius correction. The results attained were compared with crack growth experimental data.

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Gardner, G. C., and R. J. Tyrrell. "The Flow Resistance of Experimental Models of Naturally Occurring Cracks." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 200, no. 4 (July 1986): 245–50. http://dx.doi.org/10.1243/pime_proc_1986_200_125_02.

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Naturally occurring cracks have rough surfaces which mate in such a fashion as to close the crack completely when the surfaces are pressed together. Experimental work shows that friction factors are given by a Nikuradse type of equation when the crack surfaces are widely spaced. The equation remains applicable as the crack closes until roughness elements from opposing surfaces start to overlap and then an upper limit is achieved. Further reduction in the crack wall separation causes a reduction in the friction factor, which may fall to the level applicable to a smooth-walled tortuous channel. These observations are in accord with theoretical concepts.

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Xu, Denghui, Tongcheng Han, Shengbiao Liu, and Li-Yun Fu. "Effects of randomly orienting penny-shaped cracks on the elastic properties of transversely isotropic rocks." GEOPHYSICS 85, no. 6 (October 21, 2020): MR325—MR340. http://dx.doi.org/10.1190/geo2019-0678.1.

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Fractured reservoirs, as one kind of unconventional reservoirs, have great potential for oil and gas development, and their accurate characterization requires the development of rock-physics models that better simulate real fractured rocks. However, current models focus mainly on the elastic properties of rocks with aligned cracks, while the effects of randomly orienting cracks in transversely isotropic (TI) rocks are poorly studied even though such conditions are frequently encountered in the earth. To address this problem, we have derived models for the elastic properties of rocks with a TI background permeated by 3D inclined cracks and randomly orienting cracks. Then, based on the developed models, we comprehensively study the effects of the two inclination angles (i.e., the dip angle between the cracks and the isotropic plane and the rotation angle between the cracks and the plane normal to the isotropic plane, respectively) of 3D inclined cracks on the elastic properties of TI rocks. We determine that the two angles have significant influences on the elastic coefficients and hence the elastic velocities, and that their influences on the elastic properties are varying in different directions. We further investigate the effects of crack density and aspect ratio of randomly orienting cracks on the elastic properties of the fractured rocks with a TI background. The results show that the increasing crack density and crack aspect ratio reduce the elastic coefficients and velocities for rocks with randomly orienting cracks, in which the relations between compressional-wave velocities and the crack properties (i.e., crack density and crack aspect ratio) are obtained to aid the interpretation of the acquired acoustic exploration data. The proposed new models can greatly improve the modeling capability for the elastic properties of rocks with a TI background permeated by inclined and randomly orienting cracks.

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Langer, J. S. "Models of crack propagation." Physical Review A 46, no. 6 (September 1, 1992): 3123–31. http://dx.doi.org/10.1103/physreva.46.3123.

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Khalkar, V., and S. Ramachandran. "The effect of crack geometry on non-destructive fault detection of EN 8 and EN 47 cracked cantilever beam." Noise & Vibration Worldwide 50, no. 3 (March 2019): 92–100. http://dx.doi.org/10.1177/0957456519834537.

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Since long it has been observed that the size of the crack in structures increases with time, and finally, it may lead to its catastrophic failure. Hence, it is crucial to do the vibration study of cracked structures with regard to vibration-based crack detection and the classification of cracks. So far, vibration-based non-destructive testing method is applied to many spring steel cracked cantilever beams for its possible crack detection. However, the effect of various kinds of practical cracks, that is, V-shaped and U-shaped, on the applicability of these methods has been overlooked. To investigate this issue, artificially cracks are made on the cantilever beam. By free vibration analysis, the effect of crack geometry, crack depth, and crack location on natural frequency is investigated. The natural frequency results obtained from V-shaped and U-shaped models for the same crack configurations are compared with each other and it is revealed that the results are not much sensitive for the change of crack geometry. Hence, it is clear that free vibration-based crack detection method approximately predicts the crack parameters, that is, crack location and crack depth, in structures irrespective of the crack geometry. It is also found that for the same configuration, results of natural frequency are comparatively on the lower side for U-shaped crack models than V-shaped crack models. In this study, the natural frequency of each cracked case is computed by a theoretical method and numerical method and shows good agreement. Finally, it is also observed that structural integrity of a cracked cantilever beam is a function of crack location.

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McClung, R. C. "A Simple Model for Fatigue Crack Growth Near Stress Concentrations." Journal of Pressure Vessel Technology 113, no. 4 (November 1, 1991): 542–48. http://dx.doi.org/10.1115/1.2928793.

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Fatigue crack growth rates are often difficult to predict for short cracks growing near stress concentrations. This paper presents a simple model to predict those growth rates which incorporates the phenomenon of crack closure. Crack opening stresses are shown to change significantly as cracks grow away from notches, and the simple model is designed to describe those changes. The effective stress range ratio, U, is assumed to be dependent on the local stress at the crack tip location in a corresponding uncracked body. The value of U changes with the normalized maximum stress in unnotched bodies, and this dependence can be quantified with elastic-plastic finite element models or simpler modified-Dugdale crack analyses. The local stress distribution is estimated with a Neuber analysis. A semi-empirical stress intensity factor solution is constructed and calibrated with known exact solutions. The crack growth rate is then calculated with the modified Paris law, taking crack growth constants from long crack data. The model is illustrated with a specific case study, the growth of cracks from center notches in an SAE 1026 steel. Experimental crack growth data for notches of different sizes and shapes compare favorably with the calculations. The scheme is contrasted with previous models for notch fatigue cracks. The implications of the simple model for other fatigue design problems are explored, highlighting the simplicity and generality of the model.

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Dissertations / Theses on the topic "Crack models"

1

Shademan, Sassan Steven. "Mechanism-based models of fatigue crack growth /." The Ohio State University, 2000. http://rave.ohiolink.edu/etdc/view?acc_num=osu1488203857249745.

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俞立剛 and Ligang Yu. "Orthotropic damage models for fatigue crack initiation andpropagation." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1993. http://hub.hku.hk/bib/B31233995.

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馮錦生 and Kam-sang Fung. "Fatigue crack propagation with strain energy density approach." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1989. http://hub.hku.hk/bib/B31209713.

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Sabuncuoglu, Baris. "Fatigue Crack Growth Analysis Models For Functionally Graded Materials." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/2/12607024/index.pdf.

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The objective of this study is to develop crack growth analysis methods for functionally graded materials under mode I cyclic loading by using finite element technique. The study starts with the analysis of test specimens which are given in ASTM standard E399. The material properties of specimens are assumed to be changing along the thickness direction according to a presumed variation function used for the modeling of functionally graded materials. The results of the study reveal the influence of different material variation functions on the crack growth behavior. In the second part, the growth of an elliptical crack which is a common case in engineering applications is analyzed. First, mode I cycling loading is applied perpendicular to the crack plane and crack growth profiles for a certain number of cycles are obtained for homogeneous materials. Then, the code is extended for the analysis functionally graded materials. The material properties are assumed to vary as an exponential function along the major or minor axis direction of the crack. The results can be used to examine the crack profile and material constants&rsquo
influence for a certain number of cyclic loading.

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Yu, Ligang. "Orthotropic damage models for fatigue crack initiation and propagation /." [Hong Kong : University of Hong Kong], 1993. http://sunzi.lib.hku.hk/hkuto/record.jsp?B13570377.

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黃小華 and Siu-wah Wong. "Predicition of fatigue crack propagation using strain energy density method." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1989. http://hub.hku.hk/bib/B31209506.

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Scholey, Kenneth Erwin. "Heat tranfser and crack formation in water-cooled zinc fuming furnace jackets." Thesis, University of British Columbia, 1991. http://hdl.handle.net/2429/30078.

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In the zinc slag fuming process, zinc is extracted from lead blast furnace slag by reduction with a coal/air mixture injected into the slag through submerged tuyeres. The furnace is constructed of water-cooled jackets to contain the molten bath and freeze a protective slag layer. The slag layer greatly reduces vessel wear caused by the corrosive and violently agitated bath. However, the jackets are known to develop cracks in the working face panel that initiate on the slag face and propagate towards the water cavity. If the cracks reach the water cavity explosions may result should the molten slag come into contact with the water. In this study an analysis of heat transfer in the jacket has been carried out using in-plant measurements and mathematical modelling. The working face of a water jacket was instrumented with thermocouples and positioned in a fuming furnace at the Trail smelter of Cominco Ltd. Measurements revealed the presence of large thermal transients or temperature "spikes" in the panel approximately 20 cm above the tuyeres. The transients were observed during charging and tapping of the furnace and are likely associated with slag fall-off due to surface wave action and gas injection effects when the bath level is low. Temperatures at the mid-thickness were seen to rise by as much as 180 °C above the steady-state level. Under these conditions large compressive stresses are produced in the panel that are sufficient to cause yielding. Over time, the transients lead to low-cycle fatigue of the working face panel with crack formation initiating at pre-existing surface flaws. A mathematical modelling analysis of the transient freezing phenomena has been carried out using the finite element method. The results indicate that the temperature spikes are associated with the sudden removal of patches of slag and molten slag coming into direct contact with the jacket. The temperature spikes are large enough to generate compressive stresses that cause yielding of the material in the exposed area. In order to reduce the damage caused by the removal of the slag shell an increased number of anchoring studs should be used in critical areas and a higher water circulation velocity should be employed to increase the size of the frozen slag layer and its strength.
Applied Science, Faculty of
Materials Engineering, Department of
Graduate

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8

Nguyen, Olivier T. Ortiz Michael. "Cohesive models of fatigue crack growth and stress-corrosion cracking /." Diss., Pasadena, Calif. : California Institute of Technology, 2002. http://resolver.caltech.edu/CaltechETD:etd-12032004-161201.

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9

鄧偉 and Wei Deng. "Advances in interfacial crack/inclusion problems and constitutive models in solids." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1997. http://hub.hku.hk/bib/B31235748.

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Deng, Wei. "Advances in interfacial crack/inclusion problems and constitutive models in solids /." Hong Kong : University of Hong Kong, 1997. http://sunzi.lib.hku.hk/hkuto/record.jsp?B18404340.

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Books on the topic "Crack models"

1

Carpinteri, Alberto. Nonlinear Crack Models for Nonmetallic Materials. Dordrecht: Springer Netherlands, 1999.

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Carpinteri, Alberto, ed. Nonlinear Crack Models for Nonmetallic Materials. Dordrecht: Springer Netherlands, 1999. http://dx.doi.org/10.1007/978-94-011-4700-2.

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3

Reuter, WG, JH Underwood, and JC Newman, eds. Surface-Crack Growth: Models, Experiments, and Structures. 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959: ASTM International, 1990. http://dx.doi.org/10.1520/stp1060-eb.

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4

Mi, Yaoming. Three-dimensional analysis of crack growth. Southampton, UK: Computational Mechanics Publications, 1996.

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Mi, Y. Three-dimensional analysis of crack growth. Southampton: Computational Mechanics, 1995.

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6

Lewicki, David G. Gear crack propagation investigations. [Washington, DC]: National Aeronautics and Space Administration, 1996.

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7

Portela, A. Dual boundary element analysis of crack growth. Southampton, UK: Computational Mechanics Publications, 1993.

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8

Prasad, N. N. V. Thermomechanical crack growth using boundary elements. Southampton: WIT Press, 1998.

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9

Crack growth in concrete using boundary elements. Southampton, UK: Computational Mechanics Publications, 1997.

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10

Kitamura, Takayuki. Stochastic modeling of crack initiation and short-crack growth under creep and creep-fatigue conditions. [Washington, D.C.]: NASA, 1989.

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Book chapters on the topic "Crack models"

1

Carpinteri, Alberto. "Nonlinear Crack Models." In Solid Mechanics and Its Applications, 239–341. Dordrecht: Springer Netherlands, 2021. http://dx.doi.org/10.1007/978-94-024-2026-5_6.

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Cervenka, Vladimir, Jana Markova, Jan Mlcoch, Alejandro Perez Caldentey, Tereza Sajdlova, and Miroslav Sykora. "Uncertainties of Crack Width Models." In High Tech Concrete: Where Technology and Engineering Meet, 1653–61. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-59471-2_190.

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Jirásek, Milan. "Damage and Smeared Crack Models." In Numerical Modeling of Concrete Cracking, 1–49. Vienna: Springer Vienna, 2011. http://dx.doi.org/10.1007/978-3-7091-0897-0_1.

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Huespe, Alfredo E., and Javier Oliver. "Crack Models with Embedded Discontinuities." In Numerical Modeling of Concrete Cracking, 99–159. Vienna: Springer Vienna, 2011. http://dx.doi.org/10.1007/978-3-7091-0897-0_3.

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Hofstetter, G., C. Feist, H. Lehar, Y. Theiner, B. Valentini, and B. Winkler. "Plasticity based crack models and applications." In Numerical Modeling of Concrete Cracking, 161–219. Vienna: Springer Vienna, 2011. http://dx.doi.org/10.1007/978-3-7091-0897-0_4.

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Willam, Kaspar, Eddy Pramono, and Stein Sture. "Fundamental Issues of Smeared Crack Models." In Fracture of Concrete and Rock, 142–57. New York, NY: Springer New York, 1989. http://dx.doi.org/10.1007/978-1-4612-3578-1_15.

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Newby, Martin. "Statistical Approaches to Fatigue Crack Growth Models." In 10th Advances in Reliability Technology Symposium, 68–78. Dordrecht: Springer Netherlands, 1988. http://dx.doi.org/10.1007/978-94-009-1355-4_7.

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Webster, G. A., and R. A. Ainsworth. "Models for creep crack initiation and growth." In High Temperature Component Life Assessment, 132–74. Dordrecht: Springer Netherlands, 1994. http://dx.doi.org/10.1007/978-94-017-1771-7_5.

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Rots, J. G. "Invited paper: Comparative study of crack models." In Finite Elements in Civil Engineering Applications, 17–28. London: CRC Press, 2021. http://dx.doi.org/10.1201/9781003211365-4.

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Malkin, A. I. "Kinetic Models of Brittle Crack Growth: Crack Pattern Statistics and Longevity of Solids." In PROBAMAT-21st Century: Probabilities and Materials, 161–96. Dordrecht: Springer Netherlands, 1998. http://dx.doi.org/10.1007/978-94-011-5216-7_10.

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Conference papers on the topic "Crack models"

1

Ricardo, Luiz Carlos H., Paulo De Mattos Pimenta, and Dirceu Spinelli. "A Review on Crack Closure Models." In SAE Brasil International Conference on Fatigue. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2001. http://dx.doi.org/10.4271/2001-01-4072.

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Varney, Philip, and Itzhak Green. "Rotordynamic Crack Diagnosis: Distinguishing Crack Depth and Location." In ASME Turbo Expo 2013: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/gt2013-94615.

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The goal of this work is to establish a condition monitoring regimen capable of diagnosing the depth and location of a transverse fatigue crack in a rotordynamic system. The success of an on-line crack diagnosis regimen hinges on the accuracy of the crack model used. The model should account for the depth of the crack and the localization of the crack along the shaft. Negating the influence of crack location on system response ignores a crucial component of real cracks. Two gaping crack models are presented; the first simulates a finite-width manufactured notch, while the second models an open fatigue crack. An overhung rotordynamic system is modeled, imitating an available rotordynamic test rig. Four degree-of-freedom equations of motion for both crack models are presented and discussed, along with corresponding transfer matrix techniques. Free and forced response analyses are performed, with emphasis placed on results applicable to condition monitoring. It is demonstrated that two identifiers are necessary to diagnose the crack parameters: the 2X resonance frequency and the magnitude of the 2X component of the rotor angular response at resonance. First, a contour plot of the 2X resonant shaft speed versus crack depth and location is generated. The magnitude of the 2X component of the rotor’s angular response along the desired contour is obtained, narrowing the possible pairs of crack location/depth to either one or two possibilities. Practical aspects of the diagnosis procedure are then discussed.

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Smith, C. W., D. M. Constantinescu, and C. T. Liu. "Stress Intensity Factors and Crack Paths for Cracks in Photoelastic Motor Grain Models." In ASME 2002 International Mechanical Engineering Congress and Exposition. ASMEDC, 2002. http://dx.doi.org/10.1115/imece2002-32078.

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Computational analysis and two dimensional tensile tests on single motor grain fins suggest that cracks in fin tips are most likely to originate at the coalescence of the fin end tip radius with a small radius emanating from the side of the fin. Prior studies have indicated that under internal pressure, cracks on the fin axis are subject to similar stress peaks and may grow more readily than the former types due to an absence of shear modes. The present study focuses upon two types of cracks emanating from the former location called “off-axis” cracks and attempts to differentiate from the two types by their paths and SIF values, determined by the frozen stress photoelastic method.

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Eason, Ernest, and Raj Pathania. "Crack Tip Strain Rate Models for Environmentally-Assisted Fatigue Crack Growth in Light Water Reactor Environments." In ASME 2016 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/pvp2016-63640.

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This paper demonstrates the feasibility of using theoretically-motivated crack tip strain rate (CTSR) models to estimate environmentally-assisted fatigue (EAF) crack growth rate (CGR) in light water reactor (LWR) environments. Four models, each combining one of two CTSR expressions with one of two theoretical derivations from Faraday’s Law, were fitted to measured CGR data under dynamic loadings. The four models were compared with each other and with experimental crack growth data from examples where various austenitic stainless steel base metals and nickel-alloy welds were tested in LWR environments under EAF, periodic partial unloading (PPU) with various hold times, loading gradients with increasing and decreasing stress intensity factor K (±dK/da), and constant K loading. All four models produced good fits to the data on some examples, and the models using the newer derivation performed well on all examples. Default model parameters and an equation for the distance from the crack tip at which strain rate is estimated were successful in simplifying the application of the models. Both variable effects and measured CGR were well modeled. Advantages and issues of theoretically-based CTSR models are presented.

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Xu, Jie, Zhiliang Zhang, Erling O̸stby, Ba˚rd Nyhus, and Dongbai Sun. "Numerical Analyses of Ductile Fracture Behavior in 2D Plane Strain and Axisymmetric Models Using the Complete Gurson Model." In ASME 2009 Pressure Vessels and Piping Conference. ASMEDC, 2009. http://dx.doi.org/10.1115/pvp2009-77721.

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Ductile crack growth plays an important role in the analyses of fracture behavior of structures. A strong geometry dependence of ductile crack growth resistance emerges under large scale yielding conditions. This geometry dependence is associated with different levels of crack tip constraint. However, an independent relationship between the fracture resistance and crack tip constraint has also been observed in experimental studies for selected specimen geometries. To verify these results, crack growth resistance curves for plane strain, mode I crack growth under large scale yielding have been computed using the complete Gurson model. Single edge notched bending (SENB) and tension (SENT) specimens with three different crack geometries have been selected for the numerical analyses. Specimen size effect on ductile crack growth behavior has also been studied. In addition, the SENT specimen appears as an alternative to conventional fracture specimens to characterize fracture toughness of circumferentially cracked pipes due to its similar geometry constraint ahead of the crack tip with that of cracks in pipes. 2D axisymmetric models have been carried out to investigate the effect of biaxial loading (axial tension combined with internal pressure) on the resistance curves for pipes with long internal circumferential cracks under large scale yielding conditions.

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Meggiolaro, Marco Antonio, and Jaime Tupiassú Pinho De Castro. "An Evaluation of Elber-Type Crack Retardation Models." In SAE Brasil International Conference on Fatigue. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2001. http://dx.doi.org/10.4271/2001-01-4063.

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Nguyen, Vinh Phu, Giang Dinh Nguyen, Daniel Dias-da-Costa, Luming Shen, and Chi Thanh Nguyen. "Crack growth modelling: enriched continuum vs. discrete models." In International Conference on Performance-based and Life-cycle Structural Engineering. School of Civil Engineering, The University of Queensland, 2015. http://dx.doi.org/10.14264/uql.2016.1090.

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Aldarrab, Nada, and Jonathan May. "Can Sequence-to-Sequence Models Crack Substitution Ciphers?" In Proceedings of the 59th Annual Meeting of the Association for Computational Linguistics and the 11th International Joint Conference on Natural Language Processing (Volume 1: Long Papers). Stroudsburg, PA, USA: Association for Computational Linguistics, 2021. http://dx.doi.org/10.18653/v1/2021.acl-long.561.

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Lu, Kai, Koichi Masaki, Jinya Katsuyama, and Yinsheng Li. "Development of Crack Evaluation Models for Probabilistic Fracture Mechanics Analyses of Japanese Reactor Pressure Vessels." In ASME 2018 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/pvp2018-84965.

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In Japan, a probabilistic fracture mechanics (PFM) analysis code PASCAL has been developed by Japan Atomic Energy Agency for structural integrity assessment of reactor pressure vessels (RPVs). The most recent release is PASCAL Version 4 (hereafter, PSACAL4) which can be used to evaluate the failure frequency of RPVs considering neutron irradiation embrittlement and pressurized thermal shock events. For the integrity assessment of RPVs, development of crack evaluation models is important. In this study, finite element analyses are performed firstly to verify the stress intensity factor calculations of cracks in PASCAL4. In addition, the applicability of the crack evaluation models in PASCAL4 such as the location of embedded cracks, crack shape and depth of surface cracks, and the increment of crack propagation is investigated. Based on sensitivity analyses of crack evaluation models for Japanese RPVs using PASCAL4, the effects of these evaluation models on failure frequency are clarified. From the analysis results, crack evaluation models recommended to the failure frequency evaluation for a Japanese model RPV are discussed.

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Shack, W. J., and O. K. Chopra. "Statistical Initiation and Crack Growth Models for Stress Corrosion Cracking." In ASME 2007 Pressure Vessels and Piping Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/pvp2007-26731.

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Statistical distributions of initiation times and crack growth rates are needed for probabilistic fracture mechanics models. Times to failure in laboratory tests on small specimens are about a factor of 1000 shorter than the times to failure of comparably sized “specimens” in the field would have to be in order to get realistic component failure rates. Thus while specimen tests are useful in identifying parametric dependencies, it is unlikely that they can be used directly to develop initiation models for field components without using field data. A scaling approach is proposed to provide a method for pooling data from different size components and for extrapolating experience from one set of components to another set. Estimates of statistical distributions for initiation of stress corrosion cracks are developed from field data for BWR pipe cracking and CRDM cracking. Estimates of statistical distributions of crack growth rates are developed by combining phenomenological models for crack growth rates with expert judgment on the range of input parameters to those models.

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Reports on the topic "Crack models"

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Smith, C. W., D. M. Constantinescu, and C. T. Liu. Stress Intensity Factors and Crack Paths for Cracks in Photoelastic Motor Grain Models. Fort Belvoir, VA: Defense Technical Information Center, May 2002. http://dx.doi.org/10.21236/ada410794.

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Cox, B. N., and W. L. Morris. Integration of Statistical and Physical Models of Short Fatigue Crack Growth. Fort Belvoir, VA: Defense Technical Information Center, June 1988. http://dx.doi.org/10.21236/ada197917.

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Reuter, W. G., J. H. Underwood, and J. C. Newman. Review of ASTM Symposium on Surface Crack Growth: Models, Experiments, and Structures. Fort Belvoir, VA: Defense Technical Information Center, November 1990. http://dx.doi.org/10.21236/ada230645.

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Brooks, Craig, Kyle Honeycutt, and Scott P. Domasky. Crack Growth and Stress Intensity Prediction Techniques. Delivery Order 0004: Implementing Models and Libraries. Fort Belvoir, VA: Defense Technical Information Center, March 2006. http://dx.doi.org/10.21236/ada467841.

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Thompson, C. D., H. T. Krasodomski, N. Lewis, and G. L. Makar. Prediction of pure water stress corrosion cracking (PWSCC) in nickel base alloys using crack growth rate models. Office of Scientific and Technical Information (OSTI), February 1995. http://dx.doi.org/10.2172/353195.

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Kruzic, Jamie J., Thomas Siegmund, and Vikas Tomar. Final Report for Project 13-4791: New Mechanistic Models of Creep-Fatigue Crack Growth Interactions for Advanced High Temperature Reactor Components. Office of Scientific and Technical Information (OSTI), March 2018. http://dx.doi.org/10.2172/1427339.

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Oster, C. A., and M. J. Danielson. Model of crack electrochemistry. Office of Scientific and Technical Information (OSTI), March 1986. http://dx.doi.org/10.2172/5973736.

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Moet, A., D. Dearth, H. Aglan, A. Chudnovsky, and B. Kunin. A Probabilistic Model of Brittle Crack Formation. Fort Belvoir, VA: Defense Technical Information Center, July 1988. http://dx.doi.org/10.21236/ada198203.

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Pettit, Chris, and D. Wilson. A physics-informed neural network for sound propagation in the atmospheric boundary layer. Engineer Research and Development Center (U.S.), June 2021. http://dx.doi.org/10.21079/11681/41034.

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We describe what we believe is the first effort to develop a physics-informed neural network (PINN) to predict sound propagation through the atmospheric boundary layer. PINN is a recent innovation in the application of deep learning to simulate physics. The motivation is to combine the strengths of data-driven models and physics models, thereby producing a regularized surrogate model using less data than a purely data-driven model. In a PINN, the data-driven loss function is augmented with penalty terms for deviations from the underlying physics, e.g., a governing equation or a boundary condition. Training data are obtained from Crank-Nicholson solutions of the parabolic equation with homogeneous ground impedance and Monin-Obukhov similarity theory for the effective sound speed in the moving atmosphere. Training data are random samples from an ensemble of solutions for combinations of parameters governing the impedance and the effective sound speed. PINN output is processed to produce realizations of transmission loss that look much like the Crank-Nicholson solutions. We describe the framework for implementing PINN for outdoor sound, and we outline practical matters related to network architecture, the size of the training set, the physics-informed loss function, and challenge of managing the spatial complexity of the complex pressure.

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Yan, Yujie, and Jerome F. Hajjar. Automated Damage Assessment and Structural Modeling of Bridges with Visual Sensing Technology. Northeastern University, May 2021. http://dx.doi.org/10.17760/d20410114.

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Recent advances in visual sensing technology have gained much attention in the field of bridge inspection and management. Coupled with advanced robotic systems, state-of-the-art visual sensors can be used to obtain accurate documentation of bridges without the need for any special equipment or traffic closure. The captured visual sensor data can be post-processed to gather meaningful information for the bridge structures and hence to support bridge inspection and management. However, state-of-the-practice data postprocessing approaches require substantial manual operations, which can be time-consuming and expensive. The main objective of this study is to develop methods and algorithms to automate the post-processing of the visual sensor data towards the extraction of three main categories of information: 1) object information such as object identity, shapes, and spatial relationships - a novel heuristic-based method is proposed to automate the detection and recognition of main structural elements of steel girder bridges in both terrestrial and unmanned aerial vehicle (UAV)-based laser scanning data. Domain knowledge on the geometric and topological constraints of the structural elements is modeled and utilized as heuristics to guide the search as well as to reject erroneous detection results. 2) structural damage information, such as damage locations and quantities - to support the assessment of damage associated with small deformations, an advanced crack assessment method is proposed to enable automated detection and quantification of concrete cracks in critical structural elements based on UAV-based visual sensor data. In terms of damage associated with large deformations, based on the surface normal-based method proposed in Guldur et al. (2014), a new algorithm is developed to enhance the robustness of damage assessment for structural elements with curved surfaces. 3) three-dimensional volumetric models - the object information extracted from the laser scanning data is exploited to create a complete geometric representation for each structural element. In addition, mesh generation algorithms are developed to automatically convert the geometric representations into conformal all-hexahedron finite element meshes, which can be finally assembled to create a finite element model of the entire bridge. To validate the effectiveness of the developed methods and algorithms, several field data collections have been conducted to collect both the visual sensor data and the physical measurements from experimental specimens and in-service bridges. The data were collected using both terrestrial laser scanners combined with images, and laser scanners and cameras mounted to unmanned aerial vehicles.

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