Elastic Constants Inversion from Ultrasonic Transmission Spectra Obtained Using a Wide Aperture PVDF Sensor
10 Mar 2006-Quantitative Nondestructive Evaluation (American Institute of PhysicsAIP)-Vol. 820, Iss: 1, pp 1127-1132
TL;DR: In this article, the experimental results using this probe configuration were found to give improved transmission spectra that provided improved corroboration with the theoretical predictions based on Plane Wave Stiffness Matrix based transmission factor model.
Abstract: Ultrasonic wave propagation provides a method for Nondestructive Characterisation of the clastic constants of materials Goniometry based ultrasonic measurements were conducted in through transmission mode for isotropic and anisotropic materials using a conventional ultrasonic immersion transducer as a transmitter and a large aperture sensor made from Polyvinylidene Fluoride (PVDF) as receiver The experimental results using this probe configuration were found to give improved transmission spectra that provides improved corroboration with the theoretical predictions based on Plane Wave Stiffness‐Matrix based transmission factor model Inversion of the clastic constants of materials, from the measured ultrasonic transmission spectra, was evaluated using two methods: (a) Genetic Algorithm and (b) Targeted Reconstruction The inversions were carried out on transmission spectra obtained from both isotropic (Aluminum) and anisotropic materials (fiber reinforced graphite epoxy) The effectiveness of the large aperture receiver was also demonstrated from the results from inversion of the measured transmission spectra
TL;DR: In this article, a GA-based reconstruction procedure was used to determine the elastic constants of an orthotropic plate from ultrasonic velocity data using a forward model to generate the slowness curves from elastic constants.
Abstract: This paper reports a Genetic Algorithm (GA) based reconstruction procedure to determine the elastic constants of an orthotropic plate from ultrasonic velocity data Phase velocity measurements are carried out using ultrasonic back-reflection technique on laminated unidirectional graphite–epoxy (0)16 and quasi-isotropic graphite–epoxy (+45, −45, 0, 90)7s fiber reinforced composite plates A forward model to generate the slowness curves from elastic constants has been used to verify the quality of the reconstruction The sensitivity of the chosen GA parameters is studied As expected, out of 9 orthotropic elastic constants to be determined, the C23 and C44 found to be insensitive The GA based reconstruction using data obtained from multiple planes were evaluated and it is shown that the single plane reconstruction at a non-symmetric plane was sufficient for the computation of the seven elastic constants
TL;DR: In this paper, a modification to goniometry based ultrasonic through transmission data collection by using wide aperture low cost polyvinylidene fluoride (PVDF) based receiver is reported.
Abstract: Determination of the elastic moduli of polymer matrix based structural composite materials is necessary to characterize their strength after fabrication and while in service. This paper reports a modification to goniometry based ultrasonic through transmission data collection by using wide aperture low cost polyvinylidene fluoride (PVDF) based receiver. The use of PVDF based receiver more than satisfies the plane-wave conditions required from measurement. The use of a hybrid inversion technique which combines genetic algorithm based evolutionary approach, critical angle information and the use of stiffness invariants is implemented for determination of stiffness values from experimental transmission spectra measurements. Results for unidirectional and a multi-layered composite laminate are presented.
16 Apr 2021
TL;DR: Based on the principle of ultrasonic testing, the non-contact ultrasonic time-domain simulation testing method was developed for the debonding and weak bonding defects of composite structures as discussed by the authors, and the simulation results showed that the results are in good agreement with the theoretical calculation.
Abstract: Based on the principle of ultrasonic testing, the non-contact ultrasonic time-domain simulation testing method was developed for the debonding and weak bonding defects of composite structures. Firstly, the time-domain simulation model of the ultrasonic transmission characteristics of single-layer CFRP (carbon fiber reinforced polymer) plate is established, and the frequency spectrum of the transmission coefficient is obtained. By comparing with the plane wave theory, the results show that the simulation results are in good agreement with the theoretical calculation. Then, the ultrasonic transmission coefficient of single / double interface weakening and cohesive weakening in composite bonding structure is simulated. The simulation results show that with the decrease of interface stiffness and the deepening of cohesion weakening, the local extreme points in the transmission coefficient spectrum tend to shift to the low frequency side, and the offset of the extreme points caused by the decrease of spring stiffness is different at different frequency points.
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