The mode I crack–inclusion interaction in orthotropic medium

• An approximate formula for SIF change for orthotropic medium is proposed.
• The different mechanical properties along coordinate axis are considered.
• Mechanical constants along different directions play dissimilar influences on SIF change.
• The effect on the change of SIF due to the stiffness and shapes of inclusions is studied.
• FE analysis is conducted to validate the accuracy from the developed formula.

The interaction between a mode I crack and a symmetrical shape inclusion in an orthotropic medium subjected to the remote stress is investigated. Based on the transformation toughening theory and the Eshelby inclusion method, a closed-form formula for the change of stress intensity factor near the crack tip induced by the inclusion has been proposed. Both the stiffness and the shape for the inclusion are studied by finite element analysis to validate the developed formula. The elastic properties along the orientation perpendicular to the crack line play more influence on the change of stress intensity factor than those in the other directions.