A continuous damage approach to the fatigue process

✍ Scribed by Jan Janson

• Publisher: Elsevier Science
• Year: 1978
• Tongue: English
• Weight: 301 KB
• Volume: 10
• Category: Article
• ISSN: 0013-7944
• DOI: 10.1016/0013-7944(78)90070-x

✦ Synopsis

The fatigue process is analyzed theoretically by studying the interaction between a macroscopic crack and continuously distributed microdamage near the crack-tips. A mode I loading case is studied, using a Dugdale crack model. The results show good agreement with Paris' law for fatigue crack propagation with an exponent approximately equal to 4. The model also predicts a finite fatigue lifetime in the sense that the crack growth rate increases without limit after a finite number of load cycles. fatigue tests reported in literature (see e.g. Manson[9]).

With an exponent n = 4, eqn (20) also predicts a relation N l o~ ao -a, which is in good

agreement with the results shown in Fig. , especially for small values of ~aosy/E.

The conclusion is that the continuous damage assumption describes the crack growth process well. The method could be improved by, e.g. having the material parameter p to depend on the number of cycles, i.e. more damage creation during the first cycle or cycles of the process. Another improvement would be a more complicated assumption for ~, in eqns (9) and 04).