Influence of Prescribed Delaminations on Stiffness-Controlled Behavior of Composite Laminates

Abstract

The effect of delaminations on the stiffness-controlled behavior of laminated composites is investigated. Four panels of [±45,0,90]2s quasi-isotropic layup are fabricated from the T300/Narmco 5208 material system, three with prescribed delaminations of different rectangular shapes and orientations. Nondestructive buckling tests and vibration experiments are conducted on these panels with clamped-free and clamped-simple support boundary conditions to assess the stiffness-controlled behavior. Free-free vibration tests are also conducted to study the influence of delamiantions on higher modes. Finite-element analyses are performed to compare with the experimental results. The findings indicate that delaminations of the size considered can be tolerated for some service conditions without dire consequences.

Prediction and Detection of Failures in Laminated Composite Materials Using Neural Networks - A Review

“…Therefore natural frequencies can be used as indicative parameters of internal damage. Modal analysis can be used to quantify internal defects through shifts in the natural frequencies of a structure 23,[27][28][29] . NN simulations can accurately and robustly respond to the dynamic characteristics of LCM structures and they can be used to predict damage in LCMs.…”

Linear and Nonlinear Damage Detection Using a Scanning Laser Vibrometer

“…-In [48] shell structures with an introduced notch gave no resonance frequency changes exceeding the frequency resolution. -Different authors report that damage scenarios like fatigue cracks [44] and delaminations [38] in composite materials, do not cause important resonance frequency changes.…”

Vibration based damage detection in composite beams under temperature variations using Poincaré maps

“…The simplest way to perform a fault detection is the usage of the first several natural frequencies of a structure which can be determined from a conventional experiment. However, it seems that the lower order resonance frequencies are not always very sensitive to a damage, except in cases with a very large damage [3,[6][7][8][9]. Mode shapes are in general more sensitive to damage but they are difficult to measure and estimate from measured quantities.…”