Ultrasonic Attenuation of Carbon-Fiber Reinforced Composites (original) (raw)
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Composites Part B: Engineering, 2014
The aim of the present work is to develop the ultrasonic spectroscopy method using laser thermoelastic generation and piezoelectric detection of broadband acoustic pulses for quantitative evaluation of the influence on the ultrasonic attenuation coefficient of microscopic dispersed voids and interply delaminations in CFRP laminates. The specimens under study have different entire porosity values up to 10% determined by the X-ray computer tomography. The ultrasonic attenuation resonance is observed in all specimens governed by their periodic layered structure. The absolute maximum and the frequency bandwidth of the resonance peak depend on the total porosity level formed by the predominant type of imperfections, either of only microscopic spheroidal voids entrapped in the epoxy layers or of additional extended interply delaminations. The derived empirical relations between these parameters and the total porosity level can be used for rapid nondestructive evaluation of the structure of CFRP composite laminates subject to different manufacturing conditions.
DYNA
Laminated composites are widely used in applications when a high strength-to-weight ratio is required. Aeronautic, naval and automotive industries use these materials to reduce the weight of the vehicles and, consequently, fuel consumption. However, the fiber-reinforced laminated materials are anisotropic and the elastic properties can vary widely due to non-standardized manufacturing processes. The elastic characterization using mechanical tests is not easy, destructive and, in most cases, not all the elastic constants can be obtained. Therefore, alternative techniques are required to assure the quality of the mechanical parts and the evaluation of new materials. In this work, the implementation of the ultrasonic through-transmission technique and the characterization of some engineering materials is reported. Isotropic materials and laminated composites of carbon fiber and glass fiber in a polymer matrix were characterized by ultrasound and mechanical tests. An improved methodolog...
Ultrasonic Attenuation Characteristics of Glass-Fiber-Reinforced Polymer Hull Structure
Applied Sciences, 2021
Glass fiber-reinforced polymer (GFRP) ship structures have hull plate thicknesses of 10 mm or more and are fabricated using a higher proportion of resin matrix systems than E-glass fiber reinforcements. Therefore, GFRP is classified as a highly attenuative material, and this characteristic is a major cause of large errors in ultrasonic nondestructive testing for quality inspections. In this study, considering the aforementioned design and fabrication characteristics of GFRP ship structures, hull plate prototypes with various glass fiber weight fractions, glass contents (Gc), and laminate thicknesses were fabricated. Then, a pulse-echo ultrasonic test was performed with the fabricated prototypes, and the attenuation characteristics of the GFRP hull plates were investigated by conducting statistical analyses. These results demonstrated that with a variation of 30–50% in the Gc used for GFRP structure design, the plate thickness variation had a greater impact than the Gc variation on t...
Appl. Sci., 2020
In this paper, ultrasonic attenuation of engineering materials is evaluated comprehensively, covering metals, ceramics, polymers, fiber-reinforced composites, wood, and rocks. After verifying two reliable experimental methods, 336 measurements are conducted and their results are tabulated. Attenuation behavior is determined over broadband spectra, extending up to 15 MHz in low attenuating materials. The attenuation spectra are characterized in combination with four power law terms, with many showing linear frequency dependence, with or without Rayleigh scattering. Dislocation damping effects are re-evaluated and a new mechanism is proposed to explain some of the linear frequency dependencies. Additionally, quadratic and cubic dependencies due to Datta-Kinra scattering and Biwa scattering, respectively, are used for some materials to construct model relations. From many test results, some previously hidden behaviors emerged upon data evaluation. Effects of cold working, tempering, and annealing are complex and sometimes contradictory. Comparison to available literature was attempted for some, but most often prior data were unavailable. This collection of new attenuation data will be of value in materials selection and in designing structural health monitoring and non-destructive inspection protocols.
Acoustic Imaging of Microstructures of Carbon Fiber-Reinforced Composite Laminates
MRS Proceedings, 2001
ABSTRACTThe properties and homogeneity of a composite laminate are strongly dependent on structures and microstructures in it. The investigations have shown that the microstructures of carbon fiber-reinforced polymer composite laminates can be visualized by means of acoustic imaging techniques. The frequency of ultrasonic wave to be used is up to 50MHz. The composite laminates to be investigated include unidirectional carbon fiber-reinforced polymer composite laminates, bi-directional carbon fiber-reinforced polymer composite laminates and carbon fiber woven composite laminates. Very useful quantitative information about inside structures of the composites can be visualized in plan-section of the laminates in the depth directions by ultrasonic T-scan imaging technique. Typical results have been represented in this article.
Out-Of-Plane Permeability Evaluation of Carbon Fiber Preforms by Ultrasonic Wave Propagation
Materials
Out-of-plane permeability of reinforcement preforms is of crucial importance in the infusion of large and thick composite panels, but so far, there are no standard experimental methods for its determination. In this work, an experimental set-up for the measurement of unsaturated through thickness permeability based on the ultrasonic wave propagation in pulse echo mode is presented. A single ultrasonic transducer, working both as emitter and receiver of ultrasonic waves, was used to monitor the through thickness flow front during a vacuum assisted resin infusion experiment. The set-up was tested on three thick carbon fiber preforms, obtained by stacking thermal bonding of balanced or unidirectional plies either by automated fiber placement either by hand lay-up of unidirectional plies. The ultrasonic data were used to calculate unsaturated out-of-plane permeability using Darcy’s law. The permeability results were compared with saturated out-of-plane permeability, determined by a trad...
Integrated Ultrasonic Technique for Characterization of Composite Materials
Review of Progress in Quantitative Nondestructive Evaluation, 1993
The comprehensive non-destructive evaluation of modem composite materials requires the application of complementary techniques for the characterization of fabricated laminates. Current measurement methods, such as velocity and attenuation measurements of ultrasonic waves are, however, not integrated but require different ultrasonic and electronic system configurations. In this paper, an ultrasonic technique, previously developed by the authors for simultaneous wave speed and attenuation measurements [1], is applied to characterize composites. The amplitudes of tone-burst signals generated over a selected frequency range were measured to determine attenuation. For the determination of the wave velocity , a number of frequencies are selected at which a zero crossing of the tone-burst signal coincides with a zero crossing of a continuous reference sine wave. Various configurations of ultrasonic transducers for integrated measurements have also been investigated. A selected configuration of the ultrasonic and electronic system has been applied to characterize the porosity content in 200-ply unidirectional graphite/epoxy composite laminates. ULTRASONIC CONFIGURATION FOR MEASUREMENTS The attenuation and velocity of ultrasonic waves can be measured by using pulse-echo or through-transmission techniques. For materials with low signal loss, the information on absolute values of wave velocity and attenuation can be obtained by using multiple echoes from the bottom of the specimen. However, for materials with high porosity, one may not obtain even a single echo from the back face of the specimen due to signal loss. The use of non-contact transducers which is desirable for industrial purposes makes this problem even more difficult.
Ultrasonic Measurements of the Elastic Properties of Impacted Laminate Composites
The studies of ultrasonic wave propagation in fiber-reinforced laminates comprise many techniques. This study is to experimentally evaluate the effects of the impact-induced damages of Carbon Fiber Reinforced Plastic (CFRP) laminated composites under no stress and pre-stress conditions. A mechanical scanning acoustic reflection microscope (SAM: pulse-wave mode) was used to detect and evaluate interior damage (e.g., delamination) of the impact-induced specimens. The studies show that ultrasound provides an attractive means for non-invasive evaluation and thereby a means for understanding the results of high-velocity impact upon laminate composites.
Ultrasonic Analytic-Signal Responses From Polymer-Matrix Composite Laminates
IEEE transactions on ultrasonics, ferroelectrics, and frequency control, 2018
Ultrasound has been used to inspect composite laminates since their invention but only recently has the response from the internal plies themselves been considered of interest. This paper uses modeling techniques to make sense of the fluctuating and interfering reflections from the resin layers between plies, providing clues to the underlying inhomogeneities in the structure. It shows how the analytic signal, analyzed in terms of instantaneous amplitude, phase, and frequency, allows 3-D characterization of the microstructure. It is found that, under certain conditions, the phase becomes locked to the interfaces between plies and that the first and last plies have characteristically different instantaneous frequencies. This allows the thin resin layers between plies to be tracked through various features and anomalies found in real composite components (ply drops, tape gaps, tape overlaps, and out-of-plane wrinkles), giving crucial information about conformance to design of as-manufa...
Comparative Study of Several Methods for the Calculation of Ultrasonic Guided Waves in Composites
54th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, 2013
The objective of this study is studying the different predictive models for evaluating dispersion curves of ultrasonic guided waves in composites. The paper reviews different algorithms used for wave propagation analysis in layered composite plates: a) Transfer Matrix (TM), (b) Global Matrix (GM), (c) Semi-Analytical Finite Element method (SAFE), (d) local interaction simulation approach (LISA), and (e) Equivalent Matrix (EM) method applied on cross-ply cases. Description of each technique is covered, then, advantages and distinct features of those techniques are presented. Case studies for unidirectional, cross ply, and general quasi isotropic laminates are presented. Finally, the paper ends by experimental and finite element simulation studies on glass fiber reinforced polymer composites (GFRP).