Stress Intensity Factors for Viscoelastic Axisymmetric Problems Applied to Wood

Abstract

ABSTRACT. Many materials used in engineering applications obey to time-dependent behaviours and the mechanical fields are affected by the time effects. As a result, the evolution of the stresses and strains in these materials appear still very complex and difficult to study. Among such cases is the situation when the material has an axisymmetric shape and when it is submitted to a complex fracture loading. In this paper, the creep loading is applied on an axisymmetric viscoelastic orthotropic material and the stress intensity factors are computed in the opening mode, in the shear mode and in the mixed mode using to a finite element approach. The uncoupling method is based on M integral, combining the virtual and real mechanical fields. In the same time, the viscoelastic effects are introduced according to the generalized Kelvin-Voigt model composed by four branches. The numerical solution is obtained with an incremental viscoelastic formulation in the time domain. Using a Compact Tension Shear (CTS) specimen, the evolutions of stress intensity factor versus time are posted in each fracture mode configuration. The obtained results demonstrate the efficiency of the proposed model.

Relationship between crack propagation and the stress intensity factor in cutting parallel to the grain of hinoki (Chamaecyparis obtusa)

“…The values of fracture toughness K IC of wood reported in the former studies take the values from 0.2 to 1.0 MPa•m 1/2 [14,21]. The maximum K I values in this study were slightly smaller than the generally accepted K IC values of wood [20][21][22][23][24][25][26][27][28][29]. The reason for the discrepancy is not clear.…”

“…The outline of the series of the works can be seen in the recent reviews [18,19]. Many of the previous works have concentrated on the values of stress intensity factor K I or fracture toughness K IC of wood for the mode I fracture [20][21][22][23][24][25][26][27][28][29]. Some of them have also discussed about the mode II fracture [30][31][32][33][34][35][36].…”

M-theta Method on Mode I and II Failure of Two Cameroonian Hardwoods in Bending

“…The Influence of loading rate on the mode II fracture toughness of vinyl ester GRP where investigated by [8] in 2017. In this work bending simulation used the Mtheta method introduced by [9]- [11] in the plane constrain for linear elastic fracture mechanics to model crack growth on two Cameroonian hardwoods.…”