Assessment of damage in composite laminates through dynamic, full-spectral interrogation of fiber Bragg grating sensors

Abstract

In the past two years, there have been a large number of publications on the topic of biomimetic dry adhesives from modeling, fabrication and testing perspectives. We review and compare the most recent advances in fabrication and testing of these materials. While there is increased convergence and consensus as to what makes a good dry adhesive, the fabrication of these materials is still challenging, particularly for anisotropic or hierarchal designs. Although qualitative comparisons between different adhesive designs can be made, quantifying the exact performance and rating each design is significantly hampered by the lack of standardized testing methods. Manufacturing dry adhesives, which can reliably adhere to rough surfaces, show directional and self-cleaning behavior and are relatively simple to manufacture, is still very challenging-great strides by multiple research groups have however made these goals appear achievable within the next few years.

Instrumentation of integrally stiffened composite panel with fiber Bragg grating sensors for vibration measurements

“…The surface-mounted sensors could detect shifts in frequency responses (particularly if the driving frequencies were known), whereas the ratio in vibration amplitudes between the embedded and the surface-mounted sensors could indicate shifts in the depth of the neutral axis. The neutral axis location is an excellent indicator of the extent of damage in laminated plates during out-ofplane bending [14].…”

“…In addition, the surrounding microstructure of the composite material can create nonuniform and multi-component strain transfer along the FBG, leading to distortion of the reflected spectrum from the FBG. This distortion is often increased in the presence of impact damage [5,13,14].…”

Carbon laminates with RE doped optical fibre sensors

“…Therefore, all techniques related with temperature measurement, like thermography [9,[16][17][18], is an efficient process to evaluate fatigue damage evolution. On the other hand, embedded sensors provide a high sensitivity to subsurface damage due to their proximity to the damage features [19]. Several works can be found in the literature about Fabry-Perot and Bragg grating sensors to characterize the strain due to mechanical behaviour of the CFRP [20][21][22][23][24].…”

Monitoring damage growth in carbon/epoxy composite panels

“…Scholey et al [6] and Reifsnider et al [7] took quantitative measure of damage and saw that the S o (symmetric) mode dominated matrix crack signals while the A o (antisymmetric) mode is prominent in delamination signals. Having a distributed sensor network provides several advantages when it comes to monitoring a structure and has been utilized through lightweight fiber Bragg grating optical sensors [8], [9]. Understanding damage evolution and the role it plays in the degradation of composite materials is very important and has been studied extensively [10], [11], [12].…”