On the relationship between disbond growth and the release of strain energy

Abstract

Current prediction methods for growth of disbonds under fatigue loading are generally based on a correlation with either the maximum strain energy release rate (SERR) or the SERR range. This paper highlights some issues with this approach. In particular, it is argued that the maximum SERR or the SERR range alone do not give sufficient information to uniquely characterize the driving force for crack growth. Furthermore it is argued that the relationship between crack growth rate and loss of strain energy should be considered on the scale of the entire load cycle. By means of disbond growth experiments it is shown that there is indeed a very strong correlation between the crack growth rate and the strain energy lost during a fatigue cycle. Unlike methods based on the SERR, this correlation is not affected by the R-ratio. Based on the found correlation a possible basis for a new approach to disbond growth prediction is suggested.

Interpreting the stress ratio effect on delamination growth in composite laminates using the concept of fatigue fracture toughness

“…Recently, studies on fatigue delamination growth in composite laminates and adhesively bonded structures have been reported that evaluate the phenomena using energy principles [12][13][14][15]. In these studies, the concept of the energy dissipation rate dU/dN is correlated to the fatigue crack growth rate da/dN.…”

The relation between the strain energy release in fatigue and quasi-static crack growth

“…(1), where b is the width of the specimen. It is notable that this procedure is based on an energy balance, and it accounts for the stress ratio in its definition, often collapsing fatigue curves for different stress ratios [15][16][17][18].…”

Fatigue in fibre metal laminates: The interplay between fatigue in metals and fatigue in composites

“…Note that in the case stiffeners are bonded to the FML panel, the phenomenon is commonly referred to as adhesive disbonding or disbond growth rather than delamination. [19][20][21] In the case stiffeners are riveted to the FML panel, then the K stiffeners term can be evaluated through a methodology originally proposed by Vlieger 22,23 and later adapted by others. 24,25 3 | SUPERIMPOSING MATERIALS SUPERIMPOSES CRITICISM AND PREJUDICE What has become evident in the development of FMLs for aeronautical applications is that the combination of two distinctively different materials into a single structural material concept invites two communities to express concerns and criticism.…”