Abstract
This paper presents ultrasonic guided wave (UGW) propagation-based nondestructive testing (NDT) of an adhesively bonded composite structure (ACS). In the process, a series of scanning laser Doppler vibrometry (SLDV)-based laboratory experiments and time-domain spectral element method (SEM)-based numerical simulations were carried out on an ACS with barely visible impact damage (BVID) and a hole. A good agreement was observed between the numerical and experimental UGW signals in the cases studied. Finally, a full-field and elliptical signal processing method-based NDT strategy was proposed that uses differential damage features of the registered UGW signals to identify different types of BVIDs in the ACS.
Highlights
Nondestructive Testing of a BondedAluminum Nomex sandwich core structure materials are mainly used in the automobile and aerospace industry due to their high strength-to-weight ratio
Visible impact damage (BVID) is a type of damage that occurs due to drop impacts or mishandling of tools, leading to small or large indentations in the materials. These have a lesser impact on aluminum or steel, but on fiber-reinforced polymers, such as in glass fiber reinforced polymer (GFRP) or honeycomb structures, can cause changes due to core/core crushing or failure of the matrix
An ultrasonic guided wave (UGW) helps to evaluate such defects because they can propagate long distances, and its excitation is achieved by a piezo zirconium titanate (PZT) actuator
Summary
Aluminum Nomex sandwich core structure materials are mainly used in the automobile and aerospace industry due to their high strength-to-weight ratio. The paper [6] refers to experimental studies of identifying debonding and delamination using SLDV in honeycomb structures. The impact test on the 3D composite honeycomb structure was studied with the use of SLDV and numerical methods [9]. The evaluation of BVIDs in sandwich honeycomb plate using PZT excited guided waves [11] was presented using time-reversal methods. Analysis of honeycomb structures with debonding at varying temperature conditions was undertaken using guided waves, and identification of damage using damage index maps was shown [12]. Numerical and experimental analysis [13] of debonding in composite structures was carried out using guide waves. A sandwich plate with Nomex core and single-sided adhesively bonded aluminum facet is studied experimentally, numerically, and analytically. The elliptical signal method is not limited to the first time of arrival and does not use the differential signals
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