ON THE PHYSICAL NATURE OF THE PARIS LAW
对裂纹扩展规律Paris公式物理本质的探讨

A theoretical equation of fatigue crack growth is deduced in detail by means of dislocation dynamic theory, thermal activation theory and velocity process theory, with the two test constants in Paris equation being determined theoretically and explained by the microscopic structural parameters of the materials and the conditions of the test environments as well. The proposed theory finally discloses the physical nature of the Paris Law which has been considering an experimental result without theoretical background. It comes true that only measuring the microscopic parameters for one time, the behavior of crack propagation in any test conditions can be obtained. This temperature dependent crack propagation theory is used successfully to describe the crack growth rates of offshore structural steel A537 at different temperatures. The results from the theory are reviewed in accordance with the conclusions of published references.