Progress of Fracture Mechanics in Finland

Abstract

This chapter discusses the progress made on fracture mechanics work in Finland. Fracture mechanics work in the Metals Laboratory of the Technical Research Centre of Finland is concentrated on materials problems. The whole research program is broken down into subprograms: (1) elastic–plastic fracture mechanics, (2) micro-mechanisms of fracture, (3) dynamic fracture, (4) fatigue and corrosion fatigue, and (5) mechanisms of environment-assisted cracking. The material science problems were handled by the Metals Laboratory of the Technical Research Centre of Finland, whereas the continuum mechanics aspects and finite element calculations are performed by the Nuclear Engineering Laboratory. The actual needs of the Finnish nuclear power stations primarily determined the trends for the development of computational methods of fracture analysis in Finland. In linear fracture mechanics, a code for two-dimensional cases based on the finite element method and energy-release rate has been developed. For three-dimensional crack problems, general finite element programs are used to calculate displacement and stress fields, and the determination of the stress intensity factor is based on the shape of crack opening. In nonlinear fracture mechanics, a code for calculating J-integral has been developed. Advanced finite element technique has been applied in developing the code. One important application of fracture mechanics has been a reactor pressure vessel with cladding. Research work on fracture mechanics is related to the development of steel qualities and the use of it in steel constructions in arctic areas.