ABSTRACT
If a flawed structural member such as a bar is exposed to a tensile force of increasing magnitude, one can visualise two extreme modes of failure: separation without any previous elongation and change in cross-section, or a gradual reduction in cross-sectional area to the vanishing point. The former might be termed a perfect brittle fracture, while the second is called rupture. This book is concerned with the prevention of fracture in engineering materials containing cracks. Such materials, e.g. steels and other structural metals, will usually exhibit some plastic deformation prior to fracture. This chapter is concerned with cases where plastic deformation preceding fracture is sufficiently small to use the assumption of linear elastic material behaviour as a basis for fracture control. As the resulting approach, linear elastic fracture mechanics, further referred to as LEFM, does not form the subject of this book, the present chapter presents its principles, methods and application in summary only. Prior to this, a note on the fracture process will try to emphasise some phenomena essential to the understanding of the types of fracture discussed in the remainder of the book.
