Tìm thấy 20+ kết quả cho từ khóa "Crack propagation"
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Extended iso geometry analysis of crack propagation. The purpose of this paper is simulating the crack propagation in steel structures with isogeometry analysis (IGA). Crack propagation in isotroptic linear elastic material will be presented.. The numerical example is a rectangular plate assumed to be plane strain condition with an edge crack under uniform shear loading. It is showed that isogometry analysis is better than standard finite element method in modeling and simulating.
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Evaluation Of Crack Propagation Phenomenon In Bituminous Mix. Abstract: Crack propagation was experimentally simulated using semicircular specimen with a crack initiated on one side. The work shows that the rate of crack propagation can be described by a power relationship between the stiffness of the mixture and the number of cycles to failure, which is mixture and binder dependent..
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The crack in the material begins to grow when the stress intensity factor (K) reaches the fracture toughness (KC), which depends on the type of material and is determined through experiments. The fracture toughness of the concrete is varied 0.2÷1.4 (Wikipedia).. Crack propagation. The crack propagation speed was proposed by (Charles, 1958) as follows:.
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The dynamic stress intensity factors are important parameters, and they are used to calculate the positive maximum hoop stress to evaluate dynamic crack propagation properties.. q is a weight function, changing from q 1 near a crack-tip and q 0 at the exterior boundary of the J domain.. The stress intensity factors can then be evaluated by solving a system of linear algebraic equations:. Single mode in infinite edge crack FGM plate.
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Crack analysis in orthotropic media using the extended finite element method. Developing new enrichment functions for crack simulation in orthotropic media by the extended finite element method. Enriched Element-Free Galerkin methods for crack tip fields, International Journal for Numerical Methods in Engineering 1997;. Ventura et al. Dynamic crack propagation analysis of orthotropic media by the extended finite element method..
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Therefore, the onset of crack propagation at a certain K value depends additionally on the number of previously applied cycles.. m immediately resulted in crack propagation..
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Fatigue striations often bow out in the direction of crack propagation and generally tend to align perpendicular to the principal (macroscopic) crack propagation direction..
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Fatigue striations often bow out in the direction of crack propagation and generally tend to align perpendicular to the principal (macroscopic) crack propagation direction..
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This is an appropriate assumption when the crack is very short.. However, as the crack extends out of the notch, it has been shown that the crack growth rate will approach that for K T = 1 and a crack depth equaling the total depth of the crack and notch [14]. These assumptions using K T are conservative and will cause the model to underestimate the crack propagation life. However, under the conditions of interest, the propagation life is a small percentage of the total life..
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Consequently, the crack propagation is simply reduced to the determination of the crack prop- agation angle Θ c and the crack propagation length l c . A crucial point in this con- cept is that the velocity of the crack surface evolution has to be known to capture the propagation process..
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Fast cleavage crack propagation follows until the complete separation and loss of load carrying capacity of the disk. Throughout the loading, the RKR integral maintains the direction of the crack, while its maximum remains at the advancing crack tip. The crack propagation is not completely straight but slightly bent due to the redistribution of stresses induced by the continuous motion of the punch.
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While no definitive conclusion can be drawn from the above examples, it is important to note that crack propagation life can be sensitive to the material and its COF, the assumed initial flaw size that separates the initiation from the crack propagation phases, and the geometry of the test fixture or component.
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Each HCF cycle then increases the damage by until the crack initiates after 7740 HCF cycles in load block 3038. Thus, during HCF cycle 7741 in CCF load block 3038, the crack is considered to have initiated and begins to grow under the assumptions of fracture mechanics.. During the crack propagation phase, the crack grows under the assumptions of linear elastic fracture mechanics.
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In the next sections, the effects of loading history on the crack propagation characteristics of a material, particularly the threshold for HCF crack propagation, are discussed.. As shown above, the fatigue crack-growth threshold, a fracture mechanics concept, can be used to determine a stress level below which a crack of a given size will not grow..
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The computations, based on a assumed crack depth of 25 m, are shown to produce crack propagation lives that are relatively insensitive to the assumed initial crack size. Table 6.1, taken from [22], illustrates the insensitivity of crack propagation lives to initial crack size, a i , for four different fretting-fatigue experiments. Note for Experiment # 4, which comes closest to the HCF region, that an initial crack size as small as 64 m produces a crack propagation.
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Jr., and Hillberry, B.M., “Effect of Single Overload/Underload Cycles on Fatigue Crack Propagation”, Fatigue Crack Growth Under Spectrum Loads, ASTM STP 595, American Society for Testing and Materials, Philadelphia, 1976, pp.
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Ritchie, R.O., “Mechanisms of Fatigue-Crack Propagation in Ductile and Brittle Solids”, International Journal of Fracture pp. and Vasudevan, A.K., “Short Crack Growth Behavior”, Fatigue and Fracture Mechanics: 27th Volume, ASTM STP 1296, R.S.
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The crack growth analysis in [15] was also made in order to distinguish the initiation stage from the total life observed experimentally. The approach was to subtract the crack propagation time from an initial crack size a 0 from the total life to failure, where a 0 is the transition crack size in the Kitagawa diagram.
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A good agreement between experimental result and the numerical solution of evolu- tion of the electrical resistance with the crack propagation can be observed.. The obtained evolution of the electrical resistance shows at the same time a high level of similarity to the measured crack propagation behaviour under cyclic fatigue load.
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While it will be shown later that crack propagation can also be an important part of fretting-fatigue life prediction, even in the HCF regime, critical plane- based initiation parameters such as MSSR have been shown to be able to predict both the location of crack initiation as well as the angle of inclination of the crack formed at the surface [41, 42]..