Holographic Evaluation of Edge Delamination in Bars Bonded to a Rigid Support With Foam-Adhesive

1996 ◽  
Vol 118 (3) ◽  
pp. 330-334 ◽  
Author(s):  
S. Qin ◽  
H. M. Shang ◽  
C. L. Giam ◽  
C. E. Tee
Keyword(s):  
Theoretical Analysis ◽  
Rapid Detection ◽  
Iterative Procedure ◽  
Point Load ◽  
Nonlinear Relationship ◽  
Rigid Support ◽  
Double Exposure ◽  
Simple Method ◽  
Exposure Holography ◽  
Edge Delamination

When a bar having one end bonded to a rigid support with foam-adhesive is loaded, the high peeling stresses at the bonded edge foster edge delamination along the interface of bonding. Upon inspection by double exposure holography, with an incremental point load applied at the free end of the bar between exposures, the indistinct fringe perturbation and the unknown resilience of the foam-adhesive (quantified by its foundation modulus) impede unambiguous evaluation of the condition of adhesion. This paper describes a simple method for rapid detection and assessment of artificially created edge delamination in such bar structures. The theoretical analysis elucidates the suitability of modelling the bar as partially clamped, and having an equivalent slope at its support related to the foundation modulus. Two dimensionless parameters are defined, which have between them a linear relationship for a nondelaminated bonding but a nonlinear relationship for a delaminated one. Finally, a simple iterative procedure is described for estimating the delaminated length without having to predetermine the elasticity of the support.

Holographic Inspection of Plates Containing Areas of Localized Thickness Variation

1994 ◽  
Vol 116 (2) ◽  
pp. 162-167 ◽  
Author(s):  
H. M. Shang ◽  
M. Lwin ◽  
T. E. Tay
Keyword(s):  
Visual Detection ◽  
Accurate Estimation ◽  
Thickness Variation ◽  
Uniform Pressure ◽  
Circular Plates ◽  
Double Exposure ◽  
Simple Method ◽  
Exposure Holography ◽  
Fringe Patterns

Circular plates, under unknown clamping conditions and containing simulated defects in the form of circular localized thinning or thickening, are inspected by double-exposure holography. With an incremental uniform pressure applied between exposures, eccentric defects are readily revealed from the distinct irregular fringe patterns. In the case of central circular defects, however, the absence of distinct irregular fringe patterns does not enable easy visual detection of the defects. The simple method of analysis described in this paper, based on the fact that the displacement in a defective plate differs from that in a defect-free plate, allows easy deduction of central and eccentric defects from the fringe patterns. Furthermore, this method enables identification of the type of defect (localized thinning or thickening), the extent of thickness variation, as well as an accurate estimation of the location and size of the defect.

Estimation of Size and Depth of Debonds in Laminates From Holographic Interferometry

1992 ◽  
Vol 114 (2) ◽  
pp. 127-131 ◽  
Author(s):  
H. M. Shang ◽  
E. M. Lim ◽  
K. B. Lim
Keyword(s):  
Rigid Body ◽  
Holographic Interferometry ◽  
Rigid Body Motion ◽  
Body Motion ◽  
Accurate Assessment ◽  
Plate Model ◽  
Double Exposure ◽  
Testing Technique ◽  
Simple Method ◽  
Exposure Holography

Double-exposure holography has been shown to be a useful nondestructive testing technique for the detection of debonds in laminates when subjected to vacuum stressing. The size of a debond is estimated from the boundary containing anomalous fringes and subsequently, its depth is estimated from these fringes using a thin-plate model. Rigid-body motion is frequently present during testing, causing ambiguity in the identification of the shape of the debond and hence difficulty in the estimation of its size and depth. In this paper, a simple method is presented which isolates the effects of rigid-body motion so that accurate assessment of the detected debonds can be achieved. Also, the use of a circle to outline the ambiguous boundary is found suitable for square debonds.

Theoretical Analysis of Blood Alcohol Detection Based on Raman Spectroscopy

2011 ◽  
Vol 314-316 ◽  
pp. 682-685
Author(s):  
Yan Li ◽  
Sheng Wang ◽  
Xiao Lei Wang ◽  
Wen Kui Ma ◽  
Jun Liu
Keyword(s):  
Raman Spectroscopy ◽  
Theoretical Analysis ◽  
Human Skin ◽  
Human Blood ◽  
Rapid Detection ◽  
Health And Safety ◽  
Blood Alcohol ◽  
Alcohol Content ◽  
Broad Application ◽  
Safety Technology

This paper introduces an analysis technology in detecting the alcohol content in human blood after drunken that bases on reflectionof Raman spectroscopy. This is a fast, non-contact, health and safety technology which take advantage of the human skin. The technology has a broad application in rapid detection of alcohol content in human blood.

Automatic analysis of knee ligaments using double exposure holography

1991 ◽  
Vol 24 (6) ◽  
pp. 489
Author(s):  
Huang Zhi ◽  
Torsten Wredmark ◽  
Ulrik Willers ◽  
Ingegerd Dirtoft ◽  
Rolf B Johansson
Keyword(s):  
Automatic Analysis ◽  
Double Exposure ◽  
Knee Ligaments ◽  
Exposure Holography

Transient interference gratings and holograms in dyed plastic

1984 ◽  
Vol 62 (7) ◽  
pp. 669-673
Author(s):  
Sergio Calixto ◽  
R. A. Lessard
Keyword(s):  
Real Time ◽  
Diffraction Efficiency ◽  
Laser Light ◽  
Thick Layer ◽  
Double Exposure ◽  
Naked Eye ◽  
Sufficient Intensity ◽  
Exposure Holography ◽  
Reading Beam ◽  
Made In

Transient diffraction gratings were holographically made in dyed plastic by absorbing laser light. Mean energy values of 40 mJ/cm2 absorbed in a 3-mm thick layer were needed to make gratings that lasted about 10 s. The writing beams and a reading one of different wavelength were simultaneously made to fall on the plastic: the reading beam was diffracted by the grating, which produced transient diffracted beams of sufficient intensity to be seen by the naked eye or to be stored permanently by conventional photographic methods. Curves showing diffraction efficiency versus exposure with grating frequency as a parameter are presented. Applications to real-time single and double exposure holography are also discussed.

Switchable acoustic metagrating for three-channel retroreflection and carpet cloaking

2022 ◽  
Author(s):  
Ailing Song ◽  
Chaoyu Sun ◽  
Yanxun Xiang ◽  
Fu-Zhen Xuan
Keyword(s):  
Theoretical Analysis ◽  
Numerical Simulations ◽  
Acoustic Communication ◽  
Simple Structure ◽  
Research Work ◽  
Simple Method ◽  
Acoustic Sensing ◽  
Reflected Wave ◽  
Diffracted Waves ◽  
Potential Applications

Abstract In this paper, we propose a switchable acoustic metagrating composed of periodic grooves for realizing switchable functionalities of three-channel retroreflection and carpet cloaking. The groove parameters are determined by calculating and analyzing the reflectance of different diffracted waves, and only one propagating reflected wave is allowed. Theoretical analysis and numerical simulations are performed to validate the three-channel retroreflection and carpet cloaking performances of the proposed metagrating. Our research work provides a practical and simple method to design acoustic devices with switchable functionalities and simple structure, and has potential applications in practical fields of acoustic sensing and acoustic communication.

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