Abstract The paper deals with the identification of the delamination in composites on the basis of the information for the displacements from the surfaces of damaged bodies. The identification of the active delamination region on the interface between two layers of given composite material is a non-linear programming problem that consists of minimization of a Kohn-Vogelius type of functional [3...

A recent variational mechanics analysis of microcracking damage in cross-ply laminates of the form [(S)/90n]s, where (S) is any orthotropic sublaminate much stiffer than [90n], has been extended to account for the presence of delaminations emanating from the tips of microcracks in the [902n]T sublaminate. The new two-dimensional stress analysis is used to calculate the total strain energy, effe...

Layered borosilicate zeolite precursor ERB-1P (Si/B = 11) is delaminated via isomorphous substitution of Al for B using a simple aqueous Al(NO3)3 treatment. Characterization by PXRD shows loss of long-range order, and TEM demonstrates transformation of rectilinear layers in the precursor to single and curved layers in the delaminated material. N2 physisorption and base titration confirm the exp...

Effect of elastic anisotropy on indentation-induced thin film interfacial delamination, especially, at the initiation and early growth stage, is examined. The indentation load is modeled as a constant pressure over an expanding semi-spherical cavity. The delamination process is approached by a cohesive zone model. The rest of the problem is formulated within the general anisotropic elasticity t...

Impact tests were carried out on composite laminates and composite scarf repairs, while both were subjected to in-plane loading with tensile pre-strain levels up to 5000 microstrain. The results show that pre-straining of the composite laminates has no noticeable influence on the size of the delamination area for the given impact energy of 8 J, which represents a typical barely-visible impact o...

Emphasis in the paper is placed on describing guided wave successes and challenges for applications in aircraft, composite materials and pipeline inspection. Guided wave imaging methods discussed includes such topics as line of sight, tomography, guided wave C scan, phased array, and ultrasonic vibration methods. Applications outlined encircles lap splice, bonded repair patch, fuselage corrosio...

Delamination is one of the most concern defects in drilling of composite material. Delamination depends on the factors such as feed rate, tool geometry and wear. The mechanics of drilling composite materials has been examined along with the quality of the hole and the effect of tool design parameters. The capacity of computerized tomography (CT) showing sample cross-section in a nondestructive ...

In the present research, the effects of delamination size and location on vibration characteristics of laminated composite beams are investigated both analytically and numerically. In the analytical method, the delaminated beam is modeled as four interconnected Euler–Bernoulli beams and the constrained and free mode models are both simulated. The differential stretching and the bending-extensio...

In this article, optical excitation thermographic techniques, including pulsed thermography and lock-in thermography, were used to detect foreign object defect (FOD) and delamination in CFRP. Then, vibrothermography as an ultrasonic excitation technique was used to detect these defects for the comparative purposes. Different image processing methods, including cold image subtraction (CIS), prin...