Use of a surface-mounted chirped fibre Bragg grating sensor to monitor delamination growth in a double-cantilever beam test

Measurement of interface cohesive stresses and strains evolutions with combined mixed mode crack propagation test and Backface Strain Monitoring measurements

“…However, such measuring protocol has been studied only recently for probing the cohesive stresses distribution and quantitatively evaluate CZM. The adherend strain has been measured with traditional resistive strain gauges sensors (Ferracuti et al, 2007;Carrara et al, 2011) or more recently with Fibre Bragg Grating sensors (Sanderson et al, 2012;Sans et al, 2012). The so called Backface Strain Monitoring (BSM) technique have been applied on specimen designed for strength measurement such as lap shear specimens (Goglio and Rossetto, 2011;Khoramishad et al, 2010) or scarf joints (Gacoin et al, 2009), or on specimens designed for toughness measurement such as DCB specimens (Sanderson et al, 2012; or End Notched Flexure (ENF) ones Budzik et al, 2013a.…”

“…The adherend strain has been measured with traditional resistive strain gauges sensors (Ferracuti et al, 2007;Carrara et al, 2011) or more recently with Fibre Bragg Grating sensors (Sanderson et al, 2012;Sans et al, 2012). The so called Backface Strain Monitoring (BSM) technique have been applied on specimen designed for strength measurement such as lap shear specimens (Goglio and Rossetto, 2011;Khoramishad et al, 2010) or scarf joints (Gacoin et al, 2009), or on specimens designed for toughness measurement such as DCB specimens (Sanderson et al, 2012; or End Notched Flexure (ENF) ones Budzik et al, 2013a. BSM has enable to evidence cohesive stress distribution along the bondline in case of fatigue loading (Khoramishad et al, 2010;Budzik et al, 2013b) or stationary loading (Budzik et al, 2011) which could not be achieve with the J(h) technique.…”

Estimating crack tip position in adhesively bonded joints subjected to mode II quasi‐static loading

“…13,20 Optical fibers are another practical method that provides strain measurement for crack monitoring in adhesive joints. The most common fiber optic systems are fiber Bragg gratings (FBG), 21,22 chirped FBG (CFBG), 23 and optical backscatter reflectometry (OBR). 24 Unlike FBG and CFBG, OBR offers distributed strain sensing over long distances.…”

Fatigue crack growth analysis in composite bonded joints by back face distributed strain sensing and comparison with X-ray microtomography

“…To achieve distributed sensing with only one grating, Chirped Fibre Bragg Grating (CFBG) sensors can be used. CFBGs were used by Sanderson et al [10] to monitor delamination in composite DCB specimen, by Capell et al [11] to monitor fatigue crack growth in hybrid composite/aluminium alloy single lap joint and by Palaniappan et al [12] to monitor glass fibre reinforced single lap joints. To achieve distributed sensing with high spatial resolution with one single FBG, Optical Frequency Domain Reflectometry (OFDR) was applied to a long (e.g.…”