Abstract
Adhesively bonded joints are traditionally designed using a single stress/strain curve to describe the mechanical behaviour of the adhesive. This paper addresses the validity of this assumption, given that the properties of film adhesives commonly used in bonded joints (e.g. FM 73) have been shown to demonstrate significant time dependencies both at room and high temperatures. To this end, a series of finite element analysis were conducted where the time dependent properties of the adhesive were modelled using a unified plasticity theory. The findings of this work show that, when performing certification assessments which require statements on the integrity and the durability of adhesively bonded joints subjected to complex load spectra, it may be necessary to consider an analysis which accounts for both time and load history effects.
It is also shown that, for monotonic loading under constant loading rates, the peak stress strain response of the adhesive in a double lap joint follows the Glinka hypothesis for the notch stress-strain response of metals. However, it is shown that this approximation may not be valid for complex loading spectra.
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