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Showing 1 to 20 of 21 for “"LEFM"”.
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Development of a generalized fatigue assessment approach for steel castings.
… using linear elastic fracture mechanics (LEFM) analysis. This is a research effort to address issues common in the casting industry, as current fatigue assessment approaches can be too conservative leading to overdesigned parts and the use of computationally expensive methods. The model …
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Modeling of nano-scale fracture mechanisms in a graphene sheet using the atomistic j-integral
… from linear elastic fracture mechanics (LEFM) predictions. Crack-tip bond-order based prediction of critical value of stress intensity factor is also addressed in this work. The objective of this work also includes employment of an atomistic J-integral as a suitable metric for the …
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Preliminary investigation into the cracking of polyurethane
… used in Linear Elastic Fracture Mechanics (LEFM) is lost as a crack intersects a stress free surface. As a result, the stress and displacement equations are given as eigenvalue series expansions, with the lowest order eigenvalue dominating the series. The thickness averaged stress and …
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Measurement of delamination crack tip displacement in G/E laminates using scanning electron microscopy
… predicted by Linear Elastic Fracture Mechanics (LEFM). It was found that LEFM was quite accurately able to predict the shape of the profiles, but that the magnitudes were influenced by a number of physical phenomena that were encountered. The measured displacements in Mode I were nearly always …
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Reliability-based optimization of rail inspection
… predicted by linear elastic fracture mechanics (LEFM). The proposed method identifies the time-varying rail reliability due to deterioration, using data obtained from LEFM and from first-order reliability methods (FORM), which consider the uncertainty regarding the model. Since FORM is an …
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A study of fretting fatigue in aircraft components
… traditional linear elastic fracture mechanics (LEFM) to fretting fatigue are discussed. The new crack analogue concept of Giannakopoulos et al. is reviewed as a means of uniting LEFM and fretting contact mechanics to achieve a life prediction scheme for components subject to HCF that is superior …
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Hot gas welds in unplasticised polyvinyl chloride.
… A range of linear elastic fracture mechanics (LEFM) test techniques,were used to establish that,clear UPVC had a K of 2.1 MPam2 , which dropped to 1.5 MPam 2 after welding. The filled UPVC examined was too tough to allow K to be measured. However, embrittlement of the welded filled UPVC was …
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The influence of high performance matrices on fracture behavior of concrete
… While the linear elastic fracture mechanics (LEFM) concept is not appropriate for concrete, a nonlinear fracture model based on the load vs. load-line deflection and the load vs. crack-mouthopening displacement (CMOD) responses of the three-point bend tests on notched beams is proposed and …
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Impact of Uncertainties on Structures Damage Tolerance Parameters
… with Linear Elastic Fracture Mechanics (LEFM). The objective is to investigate how varying parameters affect crack growth prediction and the effectiveness of inspection strategies. The methodology involves systematically analyzing inspection intervals, considering factors like material …
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Experimental determination of the stress singularity exponent in cracked bodies using photoelasticity
… by adjusting the magnitude of the classical LEFM mode I stress intensity factor, K<sub>I</sub>. A discussion of the need to recognize and account for these effects in high-tech materials is also included.
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Effect of Galvanic Corrosion on Crack Propagation of Cold Expanded Holes in AA2024-T3
… in the Linear Elastic Fracture Mechanic (LEFM) equations to account for those effects. Galvanic corrosion of a steel fastener/aluminum plate assembly will be investigated assuming the presence of cracks in the aluminum plates. The specimens will be prepared to include an open hole with …
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Synthesis and fracture toughness of macro-defect-free (MDF) cement
… the theory of linear elastic fracture mechanics (LEFM), the loads and displacement associated with crack propagation in notched beams can be analyzed easily. A typical fracture toughness value of 1.6-1.8 MPa • m1/2 was obtained. Also, a microhardness test is used to measure fracture toughness …
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MECHANISTIC STUDY OF CRACK INITIATION AND PROPAGATION IN CROSSLINKED ULTRA HIGH MOLECULAR WEIGHT POLYETHYLENES (UHMWPE) SUBJECTED TO STATIC AND CYCLIC LOADING
… Fracture research utilizing the traditional LEFM and EPFM approaches has not yielded a definite failure criterion for UHMWPE. Therefore, an advanced viscous fracture model has been applied to various notched compact tension specimen geometries to estimate the fracture resistance. Results …
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Fatigue and fracture behaviour of PVC at elevated temperatures
… with linear elastic fracture mechanics (LEFM). Using the material properties garnered from the Paris fatigue and fracture toughness tests, lifetime predictions were made and compared to the SN data for cycles to failure The research studies revealed that there was a distinct difference in …
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Fracture characterization of clays and clay-like materials using flattened Brazilian Test
… parameter in Linear Elastic Fracture Mechanics (LEFM), the main analytical tool in studying fracture in rock, is the critical stress intensity factor that defines stress concentration near a crack tip beyond which a fracture would propagate. The basic mode of crack loading can be obtained by …
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Experimental and Numerical Methods for Characterizing the Mixed-Mode Fracture Envelope for a Tough Epoxy
… approach. Linear elastic fracture mechanics (LEFM) conditions must be valid to correctly apply these methods, however plastic deformations were observed in some adherends. Drawbacks of these approaches and their validity for analyzing PR-2930 joints were discussed. To account for …
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Solving three-dimensional problems in natural and hydraulic fracture development : insight from displacement discontinuity modeling
… and its determination plays a central role in LEFM. The DD modeling is used to evaluate SIF in Mode I, II and III at the tip of an arbitrarily-shaped embedded crack by using crack-tip element displacement discontinuity. We examine the accuracy of SIF calculation is for rectangular, …
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Spacetime damage-based cohesive model for elastodynamic fracture with dynamic contact
… from Linear Elastodynamic Fracture Mechanics (LEFM), to the cohesive-process-zone size. These ratios are, in turn, useful indicators of whether the small-scale-yielding caveat of LEFM is satisfied. A novel continuum formulation of the linear elastodynamic contact problem also supports the SDG …
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Propagation of fluid driven fractures in transversely isotropic material
… regions: a linear elastic fracture mechanics (lefm) asymptote near the tip, high-shear rate Newtonian and power law asymptotes in an intermediate region and a low-shear Newtonian asymptote in the far field. For the same dimensionless toughness, the fluid lag is smaller than for a Newtonian …
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A generalized finite element method for the simulation of non-planar three-dimensional hydraulic fracture propagation
… linear elastic fracture mechanics (LEFM) problems is also proposed. The effects of dominant in-situ stresses, orientation of wellbore, rock toughness on fracture propagation, and interaction of hydraulic fracture with wellbore are studied in detail in this work. The proposed GFEM is …
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