Cohesive Zone Modelling-CZM

Abstract

AbstractExperimental fatigue tests are very expensive and time-consuming procedures. Accordingly, numerical techniques are often employed to better understand the fatigue behavior of bonded joints and to predict their fatigue life. Several numerical techniques based on continuum mechanics, fracture mechanics and damage mechanics concepts have been proposed to estimate the fatigue response of bonded structures. Methods based on the continuum mechanics mainly focus on the initiation fatigue life while approaches based on the fracture mechanics concepts consider fatigue crack growth. But damage mechanics concepts can simulate both the fatigue life initiation and the fatigue crack propagation. Accordingly, damage mechanics approaches have recently started to attract more attention. One of the most popular of these approaches is known as cohesive zone modelling (CZM). Various types of CZMs have been proposed so far but considering the variety of the developed CZM shapes, a question that arises here is which CZM shape is more suitable for the joint analysis, a question which is answered in this chapter. Furthermore, the properties of the most common traction separation law (TSL) mentioned above are also reviewed. However, the next question is how different parameters in the considered TSL can be identified. Different techniques to shape a TSL are reviewed in this chapter including the classical methods, inverse technique, and direct approach. The last of these approaches is the most precise one since for the first two approaches the shape of the CZM should be selected beforehand. In this chapter, the constitutive laws of different CZMs are also presented and discussed. Using the constitutive laws, the cohesive models can be implemented in FE programs.