|
|
An aplication of the mathematical dislocation theory to the problem of the crack in the vicinity of the bi-material interface
Padělek, Petr ; Hrstka, Miroslav (referee) ; Profant, Tomáš (advisor)
The presented diploma thesis deals with a problem of the determination of the stress intensity factor of the finite length crack in the vicinity of the bi-material interface solved by the distributed dislocation technique. The work is divided into several parts. The first part is theoretical and includes basic concepts of the fracture mechanics, the crack behaviour at the bi-material interface, the formulation of the singular integral equation by virtue of the distributed dislocation technique, the Bueckner's principle, complex potentials and consequently the determination of the stress intensity factor. The second part is the theory application to the specific configuration of the crack of the finite length with respect to the bi-material interface and in the third part, there is carried out the solution of this problem for various configurations of the bi-material solved by the distributed dislocation technique and its comparison with the results obtained from the FE analysis.
|
|
|
Problems of the complex potentials of the isotropic elasticity
Padělek, Petr ; Druckmüller, Miloslav (referee) ; Profant, Tomáš (advisor)
The presented Bachelor Thesis investigates the problem of the complex potentials in the isotropic elasticity. The objective of the work is acquiring the components of the stress tensor and the displacement vector which describe the elasticity of continum. This problem is primarily solved on the mathematical level by means of the Airy stress function and the Muschelishvili´s complex potentials. The thesis is supplemented with the necessary theory of the elasticity and finally the concrete solution of the edge dislocation in the infinite domain is demonstrated and compared with the results acquired by FEM method.
|
|
|
Prediction of the Traction Separation Law of Ceramics Using Iterative Finite Element Modelling
Kozák, Vladislav ; Chlup, Zdeněk ; Padělek, P. ; Dlouhý, Ivo
Specific silicon nitride ceramics, the influence of the grain size and orientation on the bridging mechanisms was found. In ceramic matrix composites, crack-bridging mechanisms can provide substantial toughness enhancement coupled with the same and/or increased strength. The prediction of the crack propagation through interface elements based on the fracture mechanics approach and cohesive zone model is investigated. From a number of damage concepts the cohesive models seem to be especially attractive for the practical applications. Within the standard finite element package Abaqus a new finite element has been developed; it is written via the UEL (user’s element) procedure. Its shape can be modified according to the experimental data for the set of ceramics and composites. The element seems to be very stable from the numerical point a view. The shape of the traction separation law for four experimental materials is estimated via the iterative procedure based on the FEM modeling and experimentally determined displacement in indentation experiments, J-R curve is predicted and stability of the bridging law is tested.
|
|
|
An aplication of the mathematical dislocation theory to the problem of the crack in the vicinity of the bi-material interface
Padělek, Petr ; Hrstka, Miroslav (referee) ; Profant, Tomáš (advisor)
The presented diploma thesis deals with a problem of the determination of the stress intensity factor of the finite length crack in the vicinity of the bi-material interface solved by the distributed dislocation technique. The work is divided into several parts. The first part is theoretical and includes basic concepts of the fracture mechanics, the crack behaviour at the bi-material interface, the formulation of the singular integral equation by virtue of the distributed dislocation technique, the Bueckner's principle, complex potentials and consequently the determination of the stress intensity factor. The second part is the theory application to the specific configuration of the crack of the finite length with respect to the bi-material interface and in the third part, there is carried out the solution of this problem for various configurations of the bi-material solved by the distributed dislocation technique and its comparison with the results obtained from the FE analysis.
|
|
|
Problems of the complex potentials of the isotropic elasticity
Padělek, Petr ; Druckmüller, Miloslav (referee) ; Profant, Tomáš (advisor)
The presented Bachelor Thesis investigates the problem of the complex potentials in the isotropic elasticity. The objective of the work is acquiring the components of the stress tensor and the displacement vector which describe the elasticity of continum. This problem is primarily solved on the mathematical level by means of the Airy stress function and the Muschelishvili´s complex potentials. The thesis is supplemented with the necessary theory of the elasticity and finally the concrete solution of the edge dislocation in the infinite domain is demonstrated and compared with the results acquired by FEM method.
|
guest ::
RSS feed.