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Comparison of stability criteria of V-notched body under combined mode of loading
Klusák, Jan ; Knésl, Zdeněk
The stability criteria of V-notched bodies under combination of loading modes I and II are suggested and compared in the article. Methodology of stability criterion suggestion is based on analogy between behaviour of body with a crack and with a V-notch. Analytical approach to suggestion of stability criteria and methods of numerical estimation of magnitudes controlling stability of the concentrators are shown in the article. Corresponding evaluations are obtained from finite element method system ANSYS. Suggested criteria are mutually compared.
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Criterion of minimal value of strain energy density in case of loading of V-notched body
Klusák, Jan
Presented paper deals with suggestion of stability criterion of V-notched solids under simple loading mode I or II or under combined loading mode I + II. The methods used to propose the stability criterion are based on an analogy of behaviour of cracked and notched bodies. The paper shows strain energy density distribution in the V-notch tip vicinity. Further, direction of assumed crack propagation is determined and an approach of criterion suggestion is presented in the paper.
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Comparison of fracture behaviour of cracks and sharp notches
Klusák, Jan ; Knésl, Zdeněk
The theoretical background of linear elastic fracture mechanics of V-notches is presented. A crack is considered as a special case of the V-notch with zero open angle. Conditions for stability of a general singular stress concentrator are formulated. Based on results obtained a fracture behaviour of notches and cracks is compared.
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Evaluation of T-stress in 3D geometry
Hutař, Pavel
The three-dimensional (3D) finite element model of center cracked plate with a/W=0.5 is used to study evaluation of T-stress along the crack front. T is evaluated by direct methods and from wedge quarter-point element nodal dispacement. Results are compared and discussed from point of view of using in three-dimensional finite element models. This paper contains summary of relations for T-stress evaluation for quarter-point element nodal.
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Analysis of crack propagation in vicinity of bi-material interface in framework two parameter fracture mechanics
Seitl, Stanislav ; Knésl, Zdeněk
Existence of the interface between regions with different elastic properties have a pronounced influence on the behaviour of cracks The aim of the present contribution is an analysis of a crack growing in a vicinity of the interface between two different elastic materials.. The basic assumption of the contribution corresponds to two-parameter linear elastic fracture mechanics. The values of stress intensity factor KI and KII corresponding to normal and shear mode of loading and the value of T-stress are calculated for a generally oriented crack approaching to the interface. The calculations are performed by finite element method for short and long cracks. The dependence of KI, KII and T values on the distance and the orientation of a crack with respect to the interface is studied. It is shown that short cracks are influenced by the presence of the interface more significantly in comparison with long cracks. The results contribute to better understanding of short cracks behaviour in relation to microstructure of material.
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Influence of grain orientation on threshold values of short fatigue cracks
Náhlík, Luboš ; Knésl, Zdeněk
The influence of a grain boundary on the propagation of a fatigue crack is studied. To this aim the grain boundary is considered as an interface between two different materials with their elastic constants depending on the orientation of the adjacent grains. The main goal is to estimate the threshold value of a microstructurally short fatigue crack propagating through the grain boundary. The corresponding threshold values are calculated as a function of material parameters of grains. Corresponding modelling have been performed by combination of analytical and numerical approach. For numerical calculations the finite element system ANSYS has been used. The model describes only one of many aspects of short fatigue crack behaviour and the results obtained contribute to a better understanding of microstuctural aspects of short fatigue crack growth.
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Crack propagation analysis in multilayered pipes
Bareš, Pavel
The fracture behavior of multilayered pipes applied for water and gas distribution is analyzed in this paper. The attention is focused on numerical modeling of crack propagation through twolayered pipe. Special attention is paid to the influence of interface between the layers on fatigue crack growth. The analysis is performed under the assumption of validity of linear-elastic fracture mechanic. Numerical calculations are performed by finite element method (system ANSYS).
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