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Crack propagation through a material interface
Náhlík, Luboš
This paper describes a study of the fatigue crack propagation through a material interface of two different elastic materials under assumptions of linear elastic fracture mechanics. Two procedures for estimation of threshold value for further crack propagation from bi-material interface to the second material are suggested. Special attention is devoted to crack perpendicularly oriented to the bi-material interface. The first one is based on modified Sih?s strain energy density concept and the second one on the size of area of the plastic zone in front of the crack tip. It is shown that the corresponding fatigue threshold value is strongly influenced by the existence of an interface between two materials. As a numerical example the procedures are in applied on body with protective layer. The calculation of the corresponding threshold values and comparison of both suggested procedures is performed. Both procedures make it possible to decide whether the crack will stop at the interface or will continue growing into the second material. The results generally contribute to a better understanding of the failure of structures with protective layers.
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Crack propagation through a material interface
Náhlík, Luboš
This paper describes a study of the fatigue crack propagation through a material interface of two different elastic materials under assumptions of linear elastic fracture mechanics. Two procedures for estimation of threshold value for further crack propagation from bi-material interface to the second material are suggested. Special attention is devoted to crack perpendicularly oriented to the bi-material interface. The first one is based on modified Sih?s strain energy density concept and the second one on the size of area of the plastic zone in front of the crack tip. It is shown that the corresponding fatigue threshold value is strongly influenced by the existence of an interface between two materials. As a numerical example the procedures are in applied on body with protective layer. The calculation of the corresponding threshold values and comparison of both suggested procedures is performed. Both procedures make it possible to decide whether the crack will stop at the interface or will continue growing into the second material. The results generally contribute to a better understanding of the failure of structures with protective layers.
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Determination of T stress for arbitrary oriented crack terminating at interface between two dissimilar materials
Gröger, Roman
The most important factors describing the fracture-mechanics behavior of layered structures are the generalized stress intensity factor and also T stress describing the amplitude of the stress field independent on the radial distance from the crack tip.. Direct methods of the calculation of such parameters are well known and their accuracy is critically assessed by the experimental measurements. The present work proposes an alternative method of determining of the elastic T stress based on the validity of the reciprocal work theorem using the integration of the strain energy along a circular path surrounding the crack tip. The results obtained from a model of a crack terminating at interface between two dissimilar elastic materials are compared with the usually used direct approach. It is shown that such this term is not negligible and generally need to be taken into account in the considerations on the stability of layered materials.
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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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The influence of hardening exponent on plastic zone size
Hutař, Pavel
The influence of hardening exponent on plastic zone size was study in this paper. There is the influence of hardening exponent on crack tip opening displacement, plastic zone size, max . plastic zone size, and plastic zone area. The results are compared as a function of T-stress value.
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