Residual Strength and Fatigue Lifetime of ... - Solid Mechanics
Residual Strength and Fatigue Lifetime of ... - Solid Mechanics
Residual Strength and Fatigue Lifetime of ... - Solid Mechanics
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Chapter 5<br />
Face/Core Interface <strong>Fatigue</strong> Crack<br />
Propagation in S<strong>and</strong>wich Structures<br />
5.1 Background<br />
<strong>Fatigue</strong> behaviour <strong>of</strong> s<strong>and</strong>wich structures has been <strong>of</strong> great interest to researchers recently.<br />
S<strong>and</strong>wich specimens with <strong>and</strong> without initial damages have been fatigue tested <strong>and</strong> analysed by<br />
various authors. <strong>Fatigue</strong> analysis <strong>of</strong> undamaged s<strong>and</strong>wich beams has typically been carried out<br />
by beam bending tests to investigate the fatigue response <strong>of</strong> foam cores subjected to shear<br />
loading. Shenoi et al. (1995) conducted flexural fatigue tests on s<strong>and</strong>wich composites with glass<br />
aramid/epoxy face sheets <strong>and</strong> cross link foam. They used a ten-point configuration with simply<br />
supported ends approximating a uniformly distributed load over the span <strong>of</strong> the beam. Burman et<br />
al. (1997) analysed the fatigue response <strong>of</strong> H100 PVC <strong>and</strong> Rohacell WF51 foams by four-point<br />
bending tests on undamaged s<strong>and</strong>wich beams. Kanny <strong>and</strong> Mahfuz (2002, 2005) studied the<br />
fatigue behaviour <strong>of</strong> s<strong>and</strong>wich beams exposed to flexural loading with different loading<br />
frequencies. They found that by increasing the loading frequency, the crack growth rates in the<br />
tested s<strong>and</strong>wich beams decrease. Kulkarni et al. (2003) studied fatigue crack growth in foam<br />
cored s<strong>and</strong>wich composites exposed to flexural cyclic loading in a modified three-point bending<br />
test rig. It was observed that the first visible damage was face/core debonding in the centre <strong>of</strong> the<br />
s<strong>and</strong>wich beams. Zenkert et al. (2011) studied the failure mode shift from core shear failure to<br />
face sheet tensile failure, as a function <strong>of</strong> load amplitude in GFRP/foam cored s<strong>and</strong>wich beams.<br />
Bezazi <strong>and</strong> co-authors (2007 <strong>and</strong> 2009) investigated experimentally <strong>and</strong> analytically the fatigue<br />
behaviour <strong>of</strong> s<strong>and</strong>wich composites in a three-point bending test rig. Mahi et al. (2004) studied<br />
the flexural behaviour <strong>of</strong> s<strong>and</strong>wich composites exposed to cyclic loading in a three-point bending<br />
test rig. He proposed a damage accumulation model for the s<strong>and</strong>wich specimens <strong>and</strong> used the<br />
model to analyse the fatigue life <strong>of</strong> s<strong>and</strong>wich composites. Quispitupa <strong>and</strong> Shafigh (2006)<br />
conducted fatigue tests on s<strong>and</strong>wich beams via three-point bending. They observed both global<br />
mode I <strong>and</strong> mode II cracking in the face/core interface <strong>of</strong> the specimens. In the case <strong>of</strong> debond<br />
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