Download or read book TWO AND THREE DIMENSIONAL FINITE ELEMENT ANALYSIS OF PLASTICITY INDUCED FATIGUE CRACK CLOSURE A COMPREHENSIVE PARAMETRIC STUDY written by and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Finite element analyses are frequently used to model growing fatigue cracks and the associated plasticity-induced crack closure. Two-dimensional, elastic-perfectly plastic finite element analyses of middle-crack tension (M(T)), bend (SEB), and compact tension (C(T)) geometries were conducted to study fatigue crack closure and to calculate the crack opening values under plane-strain and plane-stress conditions. The loading was selected to give the same maximum stress intensity factor in both geometries, and thus similar initial forward plastic zone sizes. Mesh refinement studies were performed on all geometries with various element types. For the C(T) geometry, negligible crack opening loads under plane-strain conditions were observed. In contrast, for the M(T) specimen, the plane-strain crack opening stresses were found to be significantly larger. This difference was shown to be a consequence of in-plane constraint. Under plane-stress conditions, it was found that the in-plane constraint has negligible effect, such that the opening values are approximately the same for the C(T), SEB, and M(T) specimens. Next, the crack opening values of the C(T), SEB and M(T) specimens were compared under various stress levels and load ratios. The effect of a highly refined mesh on crack opening values was noted and significantly lower crack opening values than those reported in literature were found. A new methodology is presented to calculate crack opening values in planar geometries using the crack surface nodal force distribution under minimum loading as determined from finite element analyses. The calculated crack opening values are compared with values obtained using finite element analysis and more conventional crack opening assessment methodologies. It is shown that the new method is independent of loading increment, integration method (normal and reduced integration), and crack opening assessment location. The compared opening values were in good agreement with strip-yield.
Download or read book Finite Element Analysis of Plasticity Induced Fatigue Crack Closure in Three Dimensional Cracked Geometries written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Elastic-plastic finite element analyses were performed to predict the crack opening level profiles in semi-elliptical surface cracks. A script was written to use the commercial finite element code ANSYS to predict opening levels in cracked geometries. The functionality of the scripts was verified by comparing predicted opening levels in two and three-dimensional center-cracked geometries to experimental results. In addition, a parameter study was performed in which various aspects of the modeling routine were modified. This included a mesh refinement study as well as a study into the effect of a strain hardening material. The main focus of the current research, however, is to compare finite element predicted opening levels with published opening levels determined experimentally. Due to the complexities and long run-times involved with these models, no attempt was made at growing the cracks from initial length to final length. Instead, discrete crack lengths at which experimental opening levels were published were instead used. Also, no attempt was made to predict the crack aspect ratio evolution. The finite element predicted opening levels were in all cases significantly lower than those reported experimentally, however, similar trends in both crack opening level profile along the crack front, and opening level variations with crack growth were shown.
Download or read book Finite Element Analysis of Plasticity induced Fatigue Crack Closure in Three dimensional Cracked Geometries written by Jeffrey David Skinner and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: [3] The finite element predicted opening levels were in all cases significantly lower than those reported experimentally, however, similar trends in both crack opening level profile along the crack front, and opening level variations with crack growth were shown.
Download or read book Finite Element Analysis of Plasticity Induced Fatigue Crack Closure written by Mehmet Gkhan Gken and published by LAP Lambert Academic Publishing. This book was released on 2010-05 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt: In spite of the fact that the use of contact elements in modeling crack surface contact, and thus in modeling of crack closure is inherently natural, almost no effort to incorporate it in the finite element analysis of fatigue crack growth has been reported in the literature. The traditional method is based on placing truss elements on the crack surface nodes In this research contact elements are used to model crack surface contact and similar to mentioned method the determination of crack opening stress is accomplished by monitoring the state of contact elements during incrementally applied loading. Instead of determining crack opening stress of every load cycle, an algorithm that makes it possible to find crack opening stress at predetermined load cycle intervals is developed. With the developed algorithm it was possible to analyze crack closure behavior during a larger number of load cycles with less execution time. Due to simulation of relatively high number of load cycles, final stabilization of crack opening stress values after a subsequent decay in the initially "stabilized" opening stress values is observed.
Download or read book Finite Element Simulations of Three dimensional Microstructurally Small Fatigue Crack Growth in 7075 Aluminum Alloy Using Crystal Plasticity Theory written by Stephen Riley Johnston and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis discusses plasticity-induced crack closure based finite element simulations of small fatigue cracks in three dimensions utilizing crystal plasticity theory. Previously, modeling has been performed in two dimensions using a double-slip crystal plasticity material model. The goal of this work is to extend that research using a full three-dimensional FCC crystal plasticity material model implementation that accounts for all twelve FCC slip systems. Discussions of Python scripts that were written to perform analyses with the commercial finite element code ABAQUS are given. A detailed description of the modeling methodology is presented along with results for single crystals and bicrystals. The results are compared with finite element and experimental results from the literature. A discussion of preliminary work for the analysis of crack growth around an intermetallic particle is also presented.
Download or read book Finite Element Modeling of Plasticity Induced Crack Closure and a Mechanics Based Study of Crack Closure Measurement Techniques written by Marcos Lugo and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: From its discovery, crack closure was recognized as a key aspect in understanding the fatigue crack growth process. Considering the condition of plane stress, a vast amount of research has been conducted experimentally, analytically, and numerically to understand the complex process of fatigue crack growth and crack closure. Nonzero crack opening stress values are routinely observed, and it seems that there is a general agreement regarding the incidence of the phenomenon under plane stress. However, investigations regarding crack closure under plane strain conditions are less abundant. Moreover, the existence of crack closure under the plane strain state of the stress has been questioned. The importance of accurate measurements of closure to predict adequately fatigue crack growth rates should not be underestimated. Models employed to predict fatigue crack growth rates rely on plasticity-induced crack closure concepts, and the validity of plasticity-induced crack closure depends on crack closure measurements. Crack closure measurements can be performed with Elber's Method, the ASTM standard (Compliance offset method), or it may be done alternatively by the compliance ratio (CR) or the adjusted compliance ratio method (ACR). In this research, a small scale yielding two-parameter modified boundary layer analysis is performed to study the occurrence of plasticity-induced fatigue crack closure under constant amplitude loading and plane strain conditions. A wide range of T-stresses and KI levels are considered in the finite element analysis with the purpose of exploring the behavior of the crack opening stress. Crack closure was observed for some values of T-stress. Other values of T-stress resulted in an absence of closure under steady state conditions. In addition, an elastic-plastic finite element model was used to simulate a growing fatigue crack with WARP3D software. The computed displacements were used to determine the effective stress intensity factor range [delta]Keff with the ASTM standard compliance offset approach, the (CR) method, and the (ACR) method. Finally, measurement location effects on ACR and the ability of ACR method to remove residuals stresses were investigated.
Download or read book FINITE ELEMENT SIMULATIONS OF THREE DIMENSIONAL MICROSTRUCTURALLY SMALL FATIGUE CRACK GROWTH IN 7075 ALUMINUM ALLOY USING CRYSTAL PLASTICITY THEORY written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis discusses plasticity-induced crack closure based finite element simulations of small fatigue cracks in three dimensions utilizing crystal plasticity theory. Previously, modeling has been performed in two dimensions using a double-slip crystal plasticity material model. The goal of this work is to extend that research using a full three-dimensional FCC crystal plasticity material model implementation that accounts for all twelve FCC slip systems. Discussions of Python scripts that were written to perform analyses with the commercial finite element code ABAQUS are given. A detailed description of the modeling methodology is presented along with results for single crystals and bicrystals. The results are compared with finite element and experimental results from the literature. A discussion of preliminary work for the analysis of crack growth around an intermetallic particle is also presented.
Download or read book Trends in Automotive Research written by Shahrum Abdullah and published by Trans Tech Publications Ltd. This book was released on 2012-04-20 with total page 370 pages. Available in PDF, EPUB and Kindle. Book excerpt: This special issue of Trends in Automotive Research contains papers contributed to the Regional Conference on Automotive Research (ReCAR) , held on the 14 and 15th December, 2011, in Kuala Lumpur, Malaysia. The conference was organised by the Centre for Automotive Research (CAR), Faculty of Engineering and the Built Environment, Universiti Kebangsaan Malaysia. Volume is indexed by Thomson Reuters CPCI-S (WoS).
Download or read book Multiscale Behavior of Materials and Structures written by and published by . This book was released on 2006 with total page 434 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Numerical Study of Plasticity Induced Closure in Short Cracks by the Finite Element Method written by Eugene J. Bednarz and published by . This book was released on 1990 with total page 186 pages. Available in PDF, EPUB and Kindle. Book excerpt: Plasticity induced closure and its effect on the fatigue growth of short cracks were investigated analytically in a high strength titanium alloy at room temperature as well as in a nickel base alloy at elevated temperature. The analysis consisted of subjecting a single-edge cracked specimen with an initial crack length of .001 inch to cyclic loading and allowing the crack to propagate. This was accomplished using a two-dimensional finite element code and a theoretical finite element model of a typical test geometry. Visco II, the two-dimensional plane stress/plane strain finite element code, uses constant strain triangular elements and incorporates the Bodner-Partom Viscoplastic Flow Law to handle non-linear material behavior. The numerical simulations involved subjecting specimens of TI-6246 at room temperature (time-independent behavior) to cyclic loads with maximum nominal stress values of approximately 60 and 90 percent of the material yield strength and load ratios of -1.0 and 0.1 with a frequency of 1.0 Hz. The numerical simulations of specimens consisting of Inconel 718 at 1200 F (time-dependent behavior) consisted of cyclic loads where the maximum nominal stress was .90 yield strength, the applied load ratio was 0.1, and the cyclic frequencies were .01 and 1.0 Hz. The formation of a plastic wake and the affects of plasticity induced closure were observed in these specimens. (AW).
Download or read book Three dimensional Elastic plastic Finite Element Analysis of Fatigue Crack Growth and Closure written by Rahmatollah Ghadimi Chermahini and published by . This book was released on 1986 with total page 147 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Three dimensional Finite element Simulation of Fatigue crack Growth and Closure written by Stephen G. Cupschalk and published by . This book was released on 1987 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Three dimensional Finite Element Analysis of Cyclic Fatigue Crack Growth of Multiple Surface Flaws written by Corneliu Manu and published by . This book was released on 1980 with total page 500 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Finite Element Elastic Plastic Analysis of Cracks written by Satya N. Atluri and published by . This book was released on 1978 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is a summary of research performed in the areas: (a) development of two-dimensional hybrid finite element procedures to calculate stress intensity factors corresponding to general r to the minus alpha stress singularities in isotropic as well as anistropic materials; (b) study of the convergence of the assumed displacement hybrid finite element procedure in fracture mechanics problems; (c) development of a three-dimensional hybrid finite element procedure to calculate the elastic combined mode stress-intensity factors K1, K2 and K3 that vary along an arbitrarily curved three-dimensional crack front; (d) hybrid finite element solutions of fundamental three-dimensional crack problems; (e) development of a two-dimensional finite element procedure for analyzing plane problems of fracture involving large-scale yielding conditions and under cyclic loading; (f) study of the J-integral as a ductile fracture initiation condition; (g) studies of finite deformation effects near the crack-tip; (h) analysis of stable crack growth under rising load and study of criteria for loss of stability of growth in ductile materials; and (i) elastic-plastic analysis of effects of crack closure on fatigue crack growth rates. (Author).
Download or read book Finite Element Analysis of Plasticity induced Crack Closure Under Plane Strain Conditions written by N. A. Fleck and published by . This book was released on 1986 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Three dimensional Elastic plastic Finite element Analysis of Fatigue Crack Propagation written by R. G. Chermahini and published by . This book was released on 1985 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Applied mechanics reviews written by and published by . This book was released on 1948 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt:
