fracture mechanics

A postdoctoral fellow is sought to study the mechanics of magnesium alloys at the University of Waterloo, Canada, under the guidance of Dr. Worswick and Dr. Gracie. The qualified applicant will have a proven background in computational mechanics, substantiated by publications in international journals.  Preference will be given to candidates with experience coding large deformation plasticity models, coding the finite element method and with using fracture mechanics.  In addition, experience with high strain rate testing of materials is desirable.

These notes belong to a course on fracture mechanics

A crack pre-exists in a body. When the body is loaded, the two faces of the crack may simultaneously open and slide relative to each other. The crack is said to be under a mixed-mode condition. When the load reaches a critical level, the crack starts to grow, and usually kinks into a new direction. Subsequently the crack often grows along a curved path.

These notes belong to a course on fracture mechanics

Lecture 1 introduced the crack bridging model. The model is also known as the cohesive-zone model, the Barenblatt model, or the Dugdale model. The model consists of two main ingredients:

These notes belong to a course on fracture mechanics

Following Griffith (1921), we distinguish two processes: deformation in the body and separation of the body. Up to this point, the process of deformation has been described by field theories of various kinds, such as

These notes belong to a course on fracture mechanics

Lecture 1 described the Begley-Landes experiment, and the blunting of a crack due to large deformation. Lecture 2 is motivated by the following considerations.

These notes belong to a course on fracture mechanics

Decouple elastic deformation of the body and inelastic process of separation. Up to this point we have been dealing with the following situation. When a load causes a crack to extend in a body, a large part of the body is elastic, and the inelastic process of separation occurs in a zone around the front of the crack. Inelastic process of separation includes, for example, breaking of atomic bonds, growth of voids, and hysteresis in deformation.