|
| |
|
| |
|
| |
|
|
Critical stress for crack propagation in concrete
Náhlík, Luboš ; Knésl, Zdeněk
Concrete is modelled as a two-phase material. Behaviour of a crack with its tip on the interface between two different materials - hardened cement paste (matrix) and aggregate (particle) - is studied. In contrast to cracks in homogeneous materials the stress singularity for a crack terminating at the interface is of the type r -lambda, where the value of the stress singularity exponent, lambda, is in the interval 0 < lambda < 1. Than classical fracture mechanics theory and criterion cannot be applied. In the paper a new stability criterion is used to estimate the critical stress for the intersection of coarse aggregate particles.
|
|
|
Determination of a crack propagation direction initiated at the bi-material interface
Náhlík, Luboš
The strain energy density distribution in the vicinity of a crack with its tip at the bi-material interface and the generalized strain energy factor is calculated. The crack orientated arbitrarily with respect to the interface and both cases of stress singularities around the crack tip, corresponding to normal and shear modes of loading, are taken into account. The problem is solved by a combination of analytical and numerical calculations. To estimate the crack propagation direction, the generalized strain energy criterion is used. A numerical example is presented.
|
|
|
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).
|
|
| |
|
|
Modelling of crack propagation through bi-material interface
Náhlík, Luboš
Under conditions of Linear Elastic Fracture Mechanics is studied crack behaviour in front of circular particle. The typical behaviour of crack approaching the interface between matrix and particle is showen. Results of numerical calculations and applications of earlier suggested tentative fracture criteria for crack terminating at the bi-material interface are presented.
|
|
|
Interaction of crack and aggregate in concrete
Keršner, Z. ; Náhlík, Luboš ; Knésl, Zdeněk
Concrete is represented as a two-phase material in this paper. Behaviour of a single macrocrack approaching to the interface between hardened cement paste (matrix) and aggregate (particle) is modelled. It is shown that in the case of where Young modulus of cement paste is greater then those of aggregates, the effective fracture toughness of concrete is predominantly given by fracture properties of aggregates.
|
|
| |
guest ::
