摘要:

This paper presents a tensile stress evaluation of mild steel plates by chaos of Barkhausen noise. The stress of magnetic materials affects magnetic domains, so the amount of the stress can be evaluated by Barkhausen noise. After the evaluations of Barkhausen noise by the original signals, spectrums and auto‐correlation functions are performed, the reconstructed attractors which is one of the typical treatment of the chaos are examined to use them for the stress evaluation of the mild steel. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1570314

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

This study was conducted to investigate the effects of plastic deformation on magnetic Barkhausen noise (MBN) signals in mild steel. A number of mild steel samples were subjected to different degrees of uniaxial plastic deformation up to 30&percent; strain. Angular MBN measurements were done on those samples. The results indicated that plastic deformation introduces a magnetic easy axis depending on the degree of plastic deformation. A significant progression towards magnetic isotropy (no magnetic easy axis) was observed after heat‐treating the samples at low temperatures 450° C, 475° C, and 500° C. The activation energy associated with the anisotropy decrease was calculated from the low temperature annealing results using an Arrhenius‐type analysis. This was found to be 99 Kcal/mol, which is consistent with recovery‐type processes. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1570315

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

An experimental investigation of guided waves in rolled aluminum sheets has been undertaken, and a companion paper (following) reports on theoretical work relevant to these experiments. Transmitting and receiving transducers were coupled to one side of an aluminum sheet, and the propagation characteristics of linear and non‐linear elastic waves were measured. Scans of frequency and transducer separation showed the effects of mode coupling and anisotropy in the aluminum sheets, and indicated the presence of cumulative resonant harmonic generation. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1570316

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

Despite the strongly dispersive nature of guided wave propagation in isotropic planar waveguides, it is shown that material non‐linearity can result in the generation of propagating harmonics at points in the guided wave spectrum where the dispersion curves of all three orthogonal modes intersect. Experimental measurements of linear and harmonic guided wave propagation in rolled aluminum sheets have been explained in terms of the existence of a low symmetry microstructural texture in the materials. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1570317

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

With the useful lives of many aircraft being extended, in‐service inspection, repair, and related support activities represent a considerable commitment of resources. Periodic maintenance operations involve comprehensive nondestructive inspections (NDI) and significant aircraft downtime for compilation of data, disposition of results, and any needed repairs. Confining the inspections to known or suspected problem areas still requires time to cover the area adequately, and to detect and assess flaws. Reducing this inspection time requires advance knowledge of the condition of the structure with respect to the existence and probable location of defects. Recent work has demonstrated the viability of active damage interrogation (ADI) for continuous monitoring of structural health. Piezoelectric transducers are used to actively excite and sense the vibration characteristics of the structure and use this information to make estimates regarding the health of the structure. By detecting changes in the structure’s vibration signature, damage can be detected, localized, and assessed; however, additional information may be needed to accurately quantify flaws or damage. This paper will present a concept for a hybridization of ADI and NDI technologies. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1570318

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

NASA is focusing considerable efforts on technology development for Integrated Vehicle Health Management systems. The research in this area is targeted toward increasing aerospace vehicle safety and reliability, while reducing vehicle operating and maintenance costs. On‐board, real‐time sensing technologies that can provide detailed information on structural integrity are central to such a health management system. This paper describes a number of sensor technologies currently under development for integrated vehicle health management. The capabilities, current limitations, and future research needs of these technologies are addressed. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1570319

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

The operation of LaserNet Fines wear debris analysis technology is described. Application to detection and identification of mechanical faults in diesel engines is presented. The development of fault indicators directly from the LaserNet Fines analysis is described and results are related to controlled laboratory experiments. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1570320

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

Meandering Winding Magnetometer Arrays (MWM®‐Arrays) provide valuable capabilities for materials characterization and defect detection in critical structures and components fabricated from metallic materials, e.g., in aerospace applications. This paper presents recent results including: (1) crack detection and monitoring using sensors embedded between aluminum layers around a fastener, (2) detection of pre‐crack fatigue damage and cracks on shotpeened 4340 steel during a fatigue test with permanently mounted and scanning MWM‐Arrays, and (3) assessment of applied and residual stresses for 300M and 4340 steels using magnetic permeability measurements. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1570321

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

This paper describes some of the considerations involved in the development of an intelligent integrated vehicle health monitoring system from a “top‐down”, systems perspective. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1570322

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

This paper presents a tomographical reconstruction approach to quantify planar damage in plate‐like structures. By adopting the Mindlin plate theory, theoretical solutions are derived for the scattering or diffraction wave fields due to a damage represented by an inhomogeneity. The relative simplicity of Mindlin’s plate theory as opposed to the exact Rayleigh‐Lamb solution in describing both the symmetric and anti‐symmetric guided waves in plate‐like structures makes it possible to derive analytical solutions, by appealing to the first order Born approximation. The diffraction tomographic algorithm forms the basis for reconstructing the image of a structural damage, thus providing quantitative information on structural health. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1570323

出版商:AIP    

年代:1903

数据来源: AIP