Jaap Schijve – författare

This book is primarily a textbook. It is written for engineers, students and teachers, and it should also be useful for people working on various topics related to fatigue of structures and materials. The book can be used for graduate and undergraduate courses and for short courses for people already working in the industry, laboratories, or research institutes. Furthermore, the book offers various comments which can be useful to research-workers in order to consider the practical relevance of laboratory investigations and to plan future research. An important theme of the book is the understanding of what happens in the material of a structure in service if the structure is subjected to a spectrum of cyclic loads. Knowledge of the fatigue mechanism in the material and how it can be affected by a large variety of practical conditions is essential for dealing with fatigue problems. The designer of a dynamically loaded structure must “design against fatigue”. This includes not only the overall concept of the structure with related safety and economic aspects, but also questions on detail design, joints, production and material surface quality. At the same time, the designer must try to predict the fatigue performance of the structure. This requires a knowledge of the various influencing factors, also because predictions on fatigue have their limitations and shortcomings. Similar considerations arise if fatigue problems occur after a long period in service when decisions must be made on remedial actions.

Problems of fatigue under multiaxial fatigue loads have been addressed in a very large number of research publications. The present publication is primarily a survey of biaxial fatigue under constant amplitude loading on metal specimens. It starts with the physical understanding of the fatigue phenomenon under biaxial fatigue loads. Various types of proportional and non-proportional biaxial fatigue loads and biaxial stress distributions in a material are specified. Attention is paid to the fatigue limit, crack nucleation, initial micro crack growth and subsequent macro-crack in different modes of crack growth. The interference between the upper and lower surfaces of a fatigue crack is discussed. Possibilities for predictions of biaxial fatigue properties are analysed with reference to the similarity concept. The significance of the present understanding for structural design problems is considered. The book is completed with a summary of major observations.