Abstract
This paper deals with the generalization of T-integral to crack growth process in viscoelastic materials. In order to implement this expression in a finite element software, a modelling form of this integral, called Aθ, is developed. The analytical formulation is based on conservative law, independent path integral, and a combination of real, virtual displacement fields, and real, virtual thermal fields introducing, in the same time, a bilinear form of free energy density F. According to the generalization of Noether’s method, the application of Gauss Ostrogradski’s theorem combined with curvilinear cracked contour, T v is obtained. By introducing a volume domain around crack tip, the modelling expression Aθ is also defined.. Finally, the viscoelastic generalization through a thermodynamic approach, called A v , is introduced by using a discretisation of the creep tensor according to a generalized Kelvin Voigt representation.
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Abbreviations
- a, Δa:
-
Crack length and crack increment
- A1A2, B1B2:
-
Crack lips
- A(Γ1), A(Γ2):
-
Areas enclosed by Γ1 and Γ2
- A :
-
A-integral
- Aθ :
-
Modeling form of A-integral
- Aθ v :
-
Viscoelastic form of Aθ-integral
- A v :
-
Generalization of A-integral to viscoelastic behavior
- b :
-
Width specimen
- F :
-
Helmholtz strain energy density
- F • :
-
Bilinear form of strain energy density
- G v , G e :
-
Viscoelastic and elastic energy
- G W , G s :
-
External and fracture energy
- I1, I2:
-
Invariant notations
- J ijkl :
-
Four order creep compliance tensor
- J :
-
Rice’s integral
- K :
-
Kinetic energy
- \({^{u}K_{I}^{(p)}, ^{v}K_{II}^{(p)}}\) :
-
Real and virtual stress intensity factors in opening mode and shear mode induced by p th spring
- \({k_{ijkl}^p}\) :
-
Spring rigidity components
- \({\vec{n}}\) :
-
Normal vector of components n j
- \({\vec{n}_1, \vec{n}_2}\) :
-
Normal vectors to contours Γ1 and Γ2
- N :
-
Total number of Kelvin Voigt cells
- \({s_j^{(p)}}\) :
-
Roots of characteristic equation
- \({S_{11}^{(p)}, S_{22}^{(p)}, S_{12}^{(p)}, S_{33}^{(p)}}\) :
-
Compliance tensor components
- S :
-
Surface domain
- \({t, \xi, \phi, \varsigma}\) :
-
Time variables
- t c :
-
Critical time
- T :
-
T-integral
- T p :
-
New analytical form of T-integral
- T v :
-
Generalization of T-integral to viscoelastic behavior
- u, v:
-
Real and virtual displacement fields of components u i and v i
- u(p), v(p):
-
Real and virtual displacement fields in the p th spring
- U e :
-
Elastic strain energy Voigt cell
- W vis :
-
Viscous energy
- W S :
-
Fracture energy
- V :
-
Volume domain
- p :
-
Spring of pth Kelvin
- x1, x2:
-
Axis
- α (x1, x2, t):
-
Spatial and temporal function
- α t :
-
Expansion thermal coefficient
- δL :
-
Lagrangian variation
- \({\delta\tilde{u}, \delta\tilde{v}}\) :
-
Real and virtual Euleurian representation
- \({\delta{u}^{{\ast}}, \delta{v}^{{\ast}}}\) :
-
Real and virtual Lagrangian representation
- \({\eta_{ijkl}^p}\) :
-
Dash-pot viscosities components
- λ, μ :
-
Lame’s coefficients
- \({\vec{\theta}}\) :
-
Vector field
- σ ij , ε ij :
-
Elastic stress and strain tensor component
- \({\sigma_{ij}^{u}, \sigma_{ij}^v}\) :
-
Total real and virtual stress components
- \({^{(p)}\sigma_{ij}^{u}, ^{(p)}\sigma_{ij}^{v}}\) :
-
Real and virtual stress components in the p th spring
- ∂V :
-
Contour around the crack tip
- Δt :
-
Time increment
- Γ1, Γ2 :
-
Surface contours
- Ω:
-
Integration domain
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Moutou Pitti, R., Dubois, F. & Petit, C. Generalization of T and A integrals to time-dependent materials: analytical formulations. Int J Fract 161, 187–198 (2010). https://doi.org/10.1007/s10704-010-9453-1
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DOI: https://doi.org/10.1007/s10704-010-9453-1