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Ultrasonic guided wave nondestructiv...

Gardner, Michael D.

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Ultrasonic guided wave nondestructive evaluation using generalized anisotropic interface waves.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Ultrasonic guided wave nondestructive evaluation using generalized anisotropic interface waves./
作者:	Gardner, Michael D.
面頁冊數:	177 p.
附註:	Source: Dissertation Abstracts International, Volume: 75-11(E), Section: B.
Contained By:	Dissertation Abstracts International75-11B(E).
標題:	Acoustics. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3583359
ISBN:	9781321147896

Ultrasonic guided wave nondestructive evaluation using generalized anisotropic interface waves.
Gardner, Michael D.

Ultrasonic guided wave nondestructive evaluation using generalized anisotropic interface waves. - 177 p.

Source: Dissertation Abstracts International, Volume: 75-11(E), Section: B.

Thesis (Ph.D.)--The Pennsylvania State University, 2014.

The motivation for this work is a goal to inspect interfaces between thick layers of materials that can be anisotropic. The specific application is a thick composite bonded to a metal substrate. The interface is inspected for disbonds between the metal and composite. The large thickness allows the problem to be modeled as a half space. The theory behind guided waves in plates is presented. This theory includes the calculation and analysis of dispersion curves and the resulting wave structure. It is noted that for high frequency-thickness values, certain modes will converge to the half-space waves, e.g. the Rayleigh wave and the Stoneley wave. Points of high energy, especially shear energy, at the interface are desirable for interfacial inspection. Therefore, the wave structure for all modes and frequencies is searched for ideal inspection points. Interface waves are inherently good modes to use for interface inspection. Results from the dispersion curves and wave structures are verified in the finite element model software package called Abaqus. It is confirmed that the group speeds and wave structures of the modes match the predicted values.

ISBN: 9781321147896Subjects--Topical Terms:

879105
Acoustics.

Ultrasonic guided wave nondestructive evaluation using generalized anisotropic interface waves.
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100 1 $a Gardner, Michael D. $3 3180925
245 1 0 $a Ultrasonic guided wave nondestructive evaluation using generalized anisotropic interface waves.
300 $a 177 p.
500 $a Source: Dissertation Abstracts International, Volume: 75-11(E), Section: B.
500 $a Adviser: Joseph L. Rose.
502 $a Thesis (Ph.D.)--The Pennsylvania State University, 2014.
520 $a The motivation for this work is a goal to inspect interfaces between thick layers of materials that can be anisotropic. The specific application is a thick composite bonded to a metal substrate. The interface is inspected for disbonds between the metal and composite. The large thickness allows the problem to be modeled as a half space. The theory behind guided waves in plates is presented. This theory includes the calculation and analysis of dispersion curves and the resulting wave structure. It is noted that for high frequency-thickness values, certain modes will converge to the half-space waves, e.g. the Rayleigh wave and the Stoneley wave. Points of high energy, especially shear energy, at the interface are desirable for interfacial inspection. Therefore, the wave structure for all modes and frequencies is searched for ideal inspection points. Interface waves are inherently good modes to use for interface inspection. Results from the dispersion curves and wave structures are verified in the finite element model software package called Abaqus. It is confirmed that the group speeds and wave structures of the modes match the predicted values.
520 $a A theoretical development of interface waves is given wherein Rayleigh, Stoneley, and generalized interface waves are discussed. This is applied to both isotropic and anisotropic materials. It is shown that the Stoneley wave only exists for a certain range of material parameters. Because the Stoneley wave is the interface wave between two solid half spaces, it might appear that only certain pairs of solids would allow for inspection via interface wave. However, it is shown that for perturbations of the Stoneley-wave-valid material properties, interface waves which leak energy away from the interface can still propagate. They can also be used for inspection. Certain choices of materials will leak less energy and will therefore allow for longer inspection distances. The solutions to the isotropic leaky wave problem exist on eight different Riemann sheets which allow one to confine multivalued functions such as the square root onto these single-valued Riemann sheets. The ranges of existence for three of these sheets is presented along with the values of the complex wave speed. The three types of interface waves are Rayleigh-like, Stoneley, and interface. For anisotropic materials, the solutions to the anisotropic leaky wave problem exist on thirty-two different sheets and the possibility of all three displacement components being coupled exists. The predicted values of sound speed and absorption for the leaky waves are confirmed by way of a finite element simulation. The wave structure for leaky waves grows in amplitude away from the boundary in any half space where leaked energy is allowed. The leaked partial waves are visualized via a snapshot of a finite element animation.
520 $a A discussion of composite materials is given. Classical lamination theory is presented as well as the cube-cutting procedure for elastic constant determination. The composite used in this research is cut into cubes and measured; the results are presented. Physical experiments were performed on two specimens. The same unidirectional composite was bonded to both aluminum and nickel-aluminum-bronze. Mylar inserts were placed before bonding to simulate a debonding type defect. A phased array comb transducer was used to inspect the parts with varying time delays and frequencies in a mode-sweep technique to account for uncertainty in the material parameters and bonding conditions. The 1-direction (fiber-direction) results were predicted to be better than the 2-direction results because of the lower leakage and higher in-plane energy at the interface for the 1 direction. These predictions were confirmed in the experiment. These results were also found to be repeatable. An immersion scan was also performed on the aluminum part wherein the leaked energy was detected as it leaked into the water. Results showed that the 1-direction results were superior to the 2-direction results at detecting the defect. Measurement of the complex sound speed for the interface wave in the aluminum part was made. Results were within an acceptable range of predictions.
590 $a School code: 0176.
650 4 $a Acoustics. $3 879105
650 4 $a Materials science. $3 543314
690 $a 0986
690 $a 0794
710 2 $a The Pennsylvania State University. $b Acoustics. $3 3180926
773 0 $t Dissertation Abstracts International $g 75-11B(E).
790 $a 0176
791 $a Ph.D.
792 $a 2014
793 $a English
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3583359