Failure Progress of 3D Reinforced GFRP Laminate during Static Bending, Evaluated by Means of Acoustic Emission and Vibrations Analysis

Deep Learning Approach for Damage Classification Based on Acoustic Emission Data in Composite Materials

Damage detection and the classification of carbon fiber-reinforced composites using non-destructive testing (NDT) techniques are of great importance. This paper applies an acoustic emission (AE) technique to obtain AE data from three tensile damage tests determining fiber breakage, matrix cracking, and delamination. This article proposes a deep learning approach that combines a state-of-the-art deep learning technique for time series classification: the InceptionTime model with acoustic emission data for damage classification in composite materials. Raw AE time series and frequency-domain sequence data are used as the input for the InceptionTime network, and both obtain very high classification performances, achieving high accuracy scores of about 99%. The InceptionTime network produces better training, validation, and test accuracy with the raw AE time series data than it does with the frequency-domain sequence data. Simultaneously, the InceptionTime model network shows its potential in dealing with data imbalances.

An Ultrasonic Fabrication Method for Epoxy Resin/SbSI Nanowire Composites, and their Application in Nanosensors and Nanogenerators

In this manuscript, a new fabrication technology for epoxy resin/antimony sulpho-iodide (SbSI) nanowire composites is presented. SbSI nanowires, with lateral dimensions of 10 nm to 100 nm and lengths up to several micrometres, have been synthesised using ultrasound irradiation. The prepared SbSI nanowires have been bound with epoxy resin in a mass ratio of 1:4, and then ultrasound irradiation has been used again for homogenization of the mixture. The fabricated epoxy resin/SbSI nanowire composites, due to the piezoelectric properties of SbSI (electromechanical coefficient k₃₃ = 0.9, and piezoelectric coefficient d_V = 0.9 × 10⁻⁹ C/N) may be used as an active layer in nanosensors and nanogenerators. The preliminary investigations of epoxy resin/SbSI nanowire composites for sound excitation (frequency f = 175 Hz; L = 90 dB), vibrations (f = 24 Hz; A = 1 mm; F = 0.73 N), and shock wave (p = 6 bar), allowed for the determination of the composite’s open circuit voltage: 0.0153 V_RMS, 0.166 V_RMS, and 4.51 V_p-p, respectively. Maximum power output densities of 0.45 nW/cm³ and 860 nW/cm³ have been achieved for excitation by sound and vibration, respectively, for a 0.6 mm thick layer of composite.