Residual Properties in Damaged Laminated Composites through Nondestructive Testing: A Review

Abstract

The development of damage tolerance strategies in the design of composite structures constitutes a major challenge for the widespread application of composite materials. Damage tolerance approaches require a proper combination of material behavior description and nondestructive techniques. In contrast to metals, strength degradation approaches, i.e., the residual strength in presence of cracks, are not straightforwardly enforceable in composites. The nonhomogeneous nature of such materials gives rise to several failure mechanisms and, therefore, the definition of an ultimate load carrying capacity is ambiguous. Nondestructive techniques are thus increasingly required, where the damage severity is quantified not only in terms of damage extension, but also in terms of material response of the damaged region. Based on different approaches, many nondestructive techniques have been proposed in the literature, which are able to provide a quantitative description of the material state. In the present paper, a review of such nondestructive techniques for laminated composites is presented. The main objective is to analyze the damage indexes related to each method and to point out their significance with respect to the residual mechanical performances, as a result of the working principle of each retained technique. A possible guide for future research on this subject is thus outlined.

Epoxy and Bio-Based Epoxy Carbon Fiber Twill Composites: Comparison of the Quasi-Static Properties

“…Random speckle was sprayed on the specimen surface to track surface displacements and calculate the material deformation. The analysis of the results is mainly governed by the subset size parameter and by the step size parameter, which define the size of the virtual mesh of the squared subset and the distance between the subset centers, respectively [ 24 ]. In this work, the subset size was equal to 33, while the step size was equal to 8, which is less than 1/3 of the subset size, according to [ 25 ].…”

Structural Health Monitoring in Composite Structures: A Comprehensive Review

“…The fiber direction of each layer of fiber-reinforced composites is typically oriented in a direction different from the direction of other layers in order to achieve strength and stiffness in different directions. Thus, the layering of such composites can be tailored based on specific design requirements [ 29 ].…”

“…Shearography or speckle pattern shearing interferometry is an NDT technique that uses coherent light or coherent sound waves for the quality assessment of materials in different problems, such as nondestructive testing, strain measurement, and vibration analysis. It has a wide range of applications in the aerospace and wind turbine industries, among other areas [ 5 , 29 , 90 , 91 ]. The shearography techniques present several advantages over traditional NDT techniques, including (1) being capable of testing large area on the structure (up to 1 m 2 per minute [ 92 ]), (2) providing contactless techniques, (3) being relatively insensitive to environmental variations effects, and (4) performing well on honeycomb materials [ 93 ].…”

Robot-Assisted Ultrasonic Testing Technology for Complex Revolved Workpiece

“…Material of the micro cracks under different loading showed different growth trends, eventually lead to fracture. Ultrasonic testing has been applied in non-destructive testing of revolved workpieces [3][4][5][6][7][8][9]. Among these, the frame scan attached to the rotary shaft is the main form of detection and the parts that need to be tested are usually solid axes or pipe fittings with little change in diameter [10].…”