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44842 Determination of elastic constants of anisotropic materials from oblique angle ultrasonic wave measurement II: experimental
ND T Abstracts 49394 Every,A.G.," Castagnede, B.; Sachse, W. Sensitivity of inversion a l g o r i t h m s for recovering elastic constants of anisotropic solids from longitudinal wavespeed data Ultrasonics International 91, Le Touquet (France), 1-4 Jul. 1991. pp. 459-462. Butterworth Heinemann (1991). In this paper we consider the issue of sensitivity of inversion algorithms for recovering the elastic constants of anisotropic solids using only the arrival-times of ultrasonic longitudinal wave modes. A perturbation method is used to identify the elastic constants and their combinations that can he most accurately recovered from longitudinal wavespoed data and numerical simulations are used to illustrate these results. Also evaluated is the dependence of the fractional errors in the evaluated elastic constants on noise, the number of input data and the inclusion of transverse wavespeed data. 49163 Bobbin, S.E.; Wagner, J.W.; Cammarata, R.C. I n t e r p r e t a t i o n o f l a s e r - g e n e r a t e d low-order Lamb waves for elastic modulus m e a s u r e m e n t s in thin films Ultrasonics, Vol. 30, No. 2, pp. 87-90 (Mar. 1992) Variability in lamb waveform structure with film thickness, material, source laser spot size and source laser power density was observed during ultrasonic measurements for determination of elastic moduli of metallic films from 1 to 25 m u m thick. To determine the effect of waveform variability on ultrasonic velocity measurements (and, in turn, on elastic modulus calculations), a series of experiments were performed in which Lamb waves were excited in free standing films using a pulsed Nd:YAG laser and detected using heterodyne interferometry. It was shown that, regardless of waveform shape, the Lamb wave for a frequency-thickness product approaching zero.
Moreau, A. Novel ultrasonic methods for the characterization of the elastic p r o p e r t i e s and of the supermodulus effect in u n s u p p o r t e d , composition modulated thin films
49161
Dissertation Abstracts International, Vol. 52, No. 5, pp. 2607-B (Nov. 1991) (DA9129039) This work is divided into three parts. First, three novel methods to measure the velocity of acoustic waves in unsupported micron-thick films are presented. These methods employ either an interdigital transducer (IDT) or a pulsed laser to generate an acoustic wave, and either another IDT with a sliding liquid bond or a laser interferometer to detect the wave. The techniques involve measuring the time of flight of an acoustic pulse as a function of propagation distance, or the in-phase and quadrature components of a continuous wave as it travels along the film. Their abilities to study the Lamb symmetric and antisymmetric as well as the horizontal shear vibration modes of the films are compared. The film's flexural and shear moduli can be calculated. Second, the continuous wave method using two IDT's is applied to the study of the supermodulus effect. Contrary to earlier studies, the flexural, shear, biaxial and Young's moduli ate found to he nearly independent of the superlattice composition modulation wavelength. The third and last part describes the first scanning tunneling microscope capable of detecting high frequency (MHz) acoustic waves. Acoustic pulses are detected as high frequency perturbation of the tunneling current. For higher frequencies, the non-linear (rectifying) properties of the tunneling behavior allow the detection of the envelope of an acoustic burst. 48883 Wang, W., Rokhlin, S.I. M e a s u r e m e n t s o f elastic constants o f metal m a t r i x ceramic composites using ultrasonic plate m o d e antiresonances Nondestructive Characterization of Materials IV. Edited by C.O. Ruud, J.F. Bussiere and R.E. Green. pp. 105-113. Plenum Press (1991). The concept and the technique of using ultrasonic antiresonance to determine elastic constants of thin-plate anisotropic media have recently been introduced by the authors. The technique is based on measurement of obliquely incident ultrasonic beam zero-transmission angles and reconstruction from these angles of the composite elastic constants. This work focuses on measuring elastic constants of composites with only one row of fibers, whose diameter may he comparable to the sample thickness. The composite selected for this study is a 220 mum thick fiber-reinforced SiC/AI composite. The fibers (SIC) have a diameter of 65 mum and are embedded in the plane of the plate. Based on the results of this measurement we shall analyze the possibility of considering composites with only one row of fibers as an effective anisotropic medium. This question is of major importance for laminated composites. Our aim is to investigate experimentally the validity of microstructure theories applicable to a bulk composite containing multiple rows of fibers for estimation of the effective elastic constants of a sample with only one row of fibers.
48
N D T & E International 1994 Volume 27, Number 1
48861 Mal,A.K.; Karim, M.R.; Bar-Cohen, Y. Determination of the dynamic elastic moduli of composite materials by leaky lamb wave e x p e r i m e n t International Advances in Nondestructive Testing. Vol. 16, Edited by W.J. McGonnagle. pp. 77-101. Gordon and Breach Science Publishers (1991 ). An ultrasonic technique for the determination of the dynamic elastic moduli of fiber-reinforced composites through the analysis of guided wave speeds in laboratory specimens in the form of laminates is described. The wave speeds are measured by means of a recently developed technique called the leaky Lamb wave (LLW) technique. A functional relationship between the wave speed in the laminate, frequency and the dynamic elastic moduli of the material is derived through the use of a recently developed theoretical procedure. Inversion of data is carried out by means of a systematic scheme to satisfy the functional relationship in a least square sense and to obtain the frequency dependent elastic moduli of the material of the specimen. Results are presented for two unidirectional laminates and for a cross-ply laminate of different thicknesses in the frequency range of 1 to 18 MHz.
Every,A.G.; Sachse. W.: Kim, K.Y.; Niu, L. Determination of elastic constants of anisotropic solids from group velocity data
48444
Review o f Progress in Quantitative Nondestructive Evaluation, La Jolla, California (United States), 15-20 Jul. 1990. Vol. 10B, pp. 1663-1668. Edited by D.O. Thompson and D.E. Chimenti. Plenum Press (1991 ). ISBN 0-306-43903-4 There is growing use of techniques that measure the group velocities of acoustic waves or phonons in solids. The aim of this paper is to present a novel method that allows the elastic constants of an anisotropic solid to be recovered from group velocities measured in arbitrary directions in a sample. We demonstrate the method by applying it to computer generated velocity data on cubic and transversely isotropic solids and to experimental data obtained on single crystals of silicon.
Mignogna, R.B. Determination of elastic constants of anisotropic materials from oblique angle ultrasonic m e a s u r e m e n t s I: analysis
48443
Review of Progress in Quantitative Nondestructive Evaluation, La Jolla, California (United States), 15-20 Jul. 1990. Vol. 10B, pp. 1669-1675. Edited by D.O. Thompson and D.E. Chimenti. Plenum Press (1991). ISBN 0-306-43903-4 The present paper describes how oblique angle of incidence ultra.~nic velocity measurements can be analyzed to obtain the elastic constants for orthotropic (orthorhombic) materials. The analysis is verified in a 'closed-loop' manner, using computer generated data. Random error is also considered in the verification. A companion paper describes experimental measurements with details of how the time of flight measurements are analyzed to obtain the velocity and propagation direction information.
Mignogna, R.B.; Batra, N.K.; Simmonds, K.E. Determination of elastic constants of anisotropic materials from oblique angle ultrasonic wave measurement II: e x p e r i m e n t a l
48442
Review o f Progress in Quantitative NondesU'uctive Evaluation, La Jolla, California (United States), 15-20 Jui. 1990. Vol. 10B, pp. 1677-1684. Edited by D.O. Thompson and D.E. Chimenti. Plenum Press (1991). ISBN 0-306-43903-4 In this paper, we present a general and truly nondestructive method for determining all of the elastic constants for an anisotropic material of any symmetry class. The method is based on ultrasonic wave propagation along arbitrary directions in a material using a pitch-catch immersion technique with oblique angles of incidence. Although our ultimate goal is to make measurements on composite materials, we have chosen to work initially with homogeneous, anisotropic single crystals in order to validate our mathematical and experimental analysis before embarking on heterogeneous anisotropic composites. 48418 Wooh, S.C.; Daniel, I.M. Nondestructive d e t e r m i n a t i o n of elastic constants of composite
materials Review of Progress in Quantitative Nondestructive Evaluation, La Jolla, California (United States), 15-20 Jul. 1990. Vol. 10B, pp. 1445-1452. Edited by D.O. Thompson and D.E. Chimenti. Plenum Press (1991). ISBN 0-306-43903-4. This study shows that it is possible to determine properties of a transversely isotropic laminate nondestructively by ullYasonic methods. Properties measured by mechanical and ultrasonic methods, in general, are in good agreement. Moreover, the ultrasonic technique shows the advantage
Moreau, A. Novel ultrasonic methods for the characterization of the elastic p r o p e r t i e s and of the supermodulus effect in u n s u p p o r t e d , composition modulated thin films
49161
Dissertation Abstracts International, Vol. 52, No. 5, pp. 2607-B (Nov. 1991) (DA9129039) This work is divided into three parts. First, three novel methods to measure the velocity of acoustic waves in unsupported micron-thick films are presented. These methods employ either an interdigital transducer (IDT) or a pulsed laser to generate an acoustic wave, and either another IDT with a sliding liquid bond or a laser interferometer to detect the wave. The techniques involve measuring the time of flight of an acoustic pulse as a function of propagation distance, or the in-phase and quadrature components of a continuous wave as it travels along the film. Their abilities to study the Lamb symmetric and antisymmetric as well as the horizontal shear vibration modes of the films are compared. The film's flexural and shear moduli can be calculated. Second, the continuous wave method using two IDT's is applied to the study of the supermodulus effect. Contrary to earlier studies, the flexural, shear, biaxial and Young's moduli ate found to he nearly independent of the superlattice composition modulation wavelength. The third and last part describes the first scanning tunneling microscope capable of detecting high frequency (MHz) acoustic waves. Acoustic pulses are detected as high frequency perturbation of the tunneling current. For higher frequencies, the non-linear (rectifying) properties of the tunneling behavior allow the detection of the envelope of an acoustic burst. 48883 Wang, W., Rokhlin, S.I. M e a s u r e m e n t s o f elastic constants o f metal m a t r i x ceramic composites using ultrasonic plate m o d e antiresonances Nondestructive Characterization of Materials IV. Edited by C.O. Ruud, J.F. Bussiere and R.E. Green. pp. 105-113. Plenum Press (1991). The concept and the technique of using ultrasonic antiresonance to determine elastic constants of thin-plate anisotropic media have recently been introduced by the authors. The technique is based on measurement of obliquely incident ultrasonic beam zero-transmission angles and reconstruction from these angles of the composite elastic constants. This work focuses on measuring elastic constants of composites with only one row of fibers, whose diameter may he comparable to the sample thickness. The composite selected for this study is a 220 mum thick fiber-reinforced SiC/AI composite. The fibers (SIC) have a diameter of 65 mum and are embedded in the plane of the plate. Based on the results of this measurement we shall analyze the possibility of considering composites with only one row of fibers as an effective anisotropic medium. This question is of major importance for laminated composites. Our aim is to investigate experimentally the validity of microstructure theories applicable to a bulk composite containing multiple rows of fibers for estimation of the effective elastic constants of a sample with only one row of fibers.
48
N D T & E International 1994 Volume 27, Number 1
48861 Mal,A.K.; Karim, M.R.; Bar-Cohen, Y. Determination of the dynamic elastic moduli of composite materials by leaky lamb wave e x p e r i m e n t International Advances in Nondestructive Testing. Vol. 16, Edited by W.J. McGonnagle. pp. 77-101. Gordon and Breach Science Publishers (1991 ). An ultrasonic technique for the determination of the dynamic elastic moduli of fiber-reinforced composites through the analysis of guided wave speeds in laboratory specimens in the form of laminates is described. The wave speeds are measured by means of a recently developed technique called the leaky Lamb wave (LLW) technique. A functional relationship between the wave speed in the laminate, frequency and the dynamic elastic moduli of the material is derived through the use of a recently developed theoretical procedure. Inversion of data is carried out by means of a systematic scheme to satisfy the functional relationship in a least square sense and to obtain the frequency dependent elastic moduli of the material of the specimen. Results are presented for two unidirectional laminates and for a cross-ply laminate of different thicknesses in the frequency range of 1 to 18 MHz.
Every,A.G.; Sachse. W.: Kim, K.Y.; Niu, L. Determination of elastic constants of anisotropic solids from group velocity data
48444
Review o f Progress in Quantitative Nondestructive Evaluation, La Jolla, California (United States), 15-20 Jul. 1990. Vol. 10B, pp. 1663-1668. Edited by D.O. Thompson and D.E. Chimenti. Plenum Press (1991 ). ISBN 0-306-43903-4 There is growing use of techniques that measure the group velocities of acoustic waves or phonons in solids. The aim of this paper is to present a novel method that allows the elastic constants of an anisotropic solid to be recovered from group velocities measured in arbitrary directions in a sample. We demonstrate the method by applying it to computer generated velocity data on cubic and transversely isotropic solids and to experimental data obtained on single crystals of silicon.
Mignogna, R.B. Determination of elastic constants of anisotropic materials from oblique angle ultrasonic m e a s u r e m e n t s I: analysis
48443
Review of Progress in Quantitative Nondestructive Evaluation, La Jolla, California (United States), 15-20 Jul. 1990. Vol. 10B, pp. 1669-1675. Edited by D.O. Thompson and D.E. Chimenti. Plenum Press (1991). ISBN 0-306-43903-4 The present paper describes how oblique angle of incidence ultra.~nic velocity measurements can be analyzed to obtain the elastic constants for orthotropic (orthorhombic) materials. The analysis is verified in a 'closed-loop' manner, using computer generated data. Random error is also considered in the verification. A companion paper describes experimental measurements with details of how the time of flight measurements are analyzed to obtain the velocity and propagation direction information.
Mignogna, R.B.; Batra, N.K.; Simmonds, K.E. Determination of elastic constants of anisotropic materials from oblique angle ultrasonic wave measurement II: e x p e r i m e n t a l
48442
Review o f Progress in Quantitative NondesU'uctive Evaluation, La Jolla, California (United States), 15-20 Jui. 1990. Vol. 10B, pp. 1677-1684. Edited by D.O. Thompson and D.E. Chimenti. Plenum Press (1991). ISBN 0-306-43903-4 In this paper, we present a general and truly nondestructive method for determining all of the elastic constants for an anisotropic material of any symmetry class. The method is based on ultrasonic wave propagation along arbitrary directions in a material using a pitch-catch immersion technique with oblique angles of incidence. Although our ultimate goal is to make measurements on composite materials, we have chosen to work initially with homogeneous, anisotropic single crystals in order to validate our mathematical and experimental analysis before embarking on heterogeneous anisotropic composites. 48418 Wooh, S.C.; Daniel, I.M. Nondestructive d e t e r m i n a t i o n of elastic constants of composite
materials Review of Progress in Quantitative Nondestructive Evaluation, La Jolla, California (United States), 15-20 Jul. 1990. Vol. 10B, pp. 1445-1452. Edited by D.O. Thompson and D.E. Chimenti. Plenum Press (1991). ISBN 0-306-43903-4. This study shows that it is possible to determine properties of a transversely isotropic laminate nondestructively by ullYasonic methods. Properties measured by mechanical and ultrasonic methods, in general, are in good agreement. Moreover, the ultrasonic technique shows the advantage