Analysis of Pulsed Thermography Methods for Defect Depth Prediction

2005 ◽  
Vol 128 (4) ◽  
pp. 329-338 ◽  
Author(s):  
J. G. Sun
Keyword(s):  
Test Specimen ◽  
Three Dimensional ◽  
Quantitative Prediction ◽  
Defect Depth ◽  
Effective Technique ◽  
Flat Bottom ◽  
Dimensional Solution ◽  
Pulsed Thermography ◽  
One Dimensional ◽  
Depth Prediction

Pulsed thermography is an effective technique for quantitative prediction of defect depth within a specimen. Several methods have been reported in the literature. In this paper, using an analysis based on a theoretical one-dimensional solution of pulsed thermography, we analyzed four representative methods. We show that all of the methods are accurate and converge to the theoretical solution under ideal conditions. Three methods can be directly used to predict defect depth. However, because defect features that appear on the surface during a pulsed thermography test are always affected by three-dimensional heat conduction within the test specimen, the performance and accuracy of these methods differs for defects of various sizes and depths. This difference is demonstrated and evaluated from a set of pulsed thermography data obtained from a specimen with several flat-bottom holes as simulated defects.

Specified value based defect depth prediction using pulsed thermography

2012 ◽  
Vol 112 (2) ◽  
pp. 023112 ◽  
Author(s):  
Zhi Zeng ◽  
Ning Tao ◽  
Lichun Feng ◽  
Cunlin Zhang
Keyword(s):  
Defect Depth ◽  
Pulsed Thermography ◽  
Depth Prediction

Working Capability Analysis of Stewart Platforms

1996 ◽  
Vol 118 (2) ◽  
pp. 220-227 ◽  
Author(s):  
Chi-Mei Luh ◽  
F. A. Adkins ◽  
E. J. Haug ◽  
C. C. Qiu
Keyword(s):  
Numerical Methods ◽  
Motion Control ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Unilateral Constraints ◽  
Dimensional Solution ◽  
One Dimensional ◽  
Capability Analysis ◽  
Working Capability ◽  
Stewart Platforms

Working capability analysis of planar and spatial Stewart platforms with unilateral constraints on actuator length is carried out using numerical methods based on analytical criteria for the boundary of the accessible output set. Restrictions on achievable motion at singular configurations associated with points interior to the accessible output set are also analyzed. Since movement of the working point on a spatial Stewart platform occurs in three-dimensional space, the boundary of the accessible output set is a two-dimensional surface. Numerical methods used in this analysis map one-dimensional solution sets, permitting the boundary of the accessible output set to be characterized by a family of one dimensional generators. Motion control restrictions inside the accessible output set are similarly characterized by families of interior singular curves, and barriers to motion control across surfaces defined are analyzed.

scholarly journals Defect Depth Estimation in Infrared Thermography with Deep Learning

2021 ◽  
Author(s):  
Qiang Fang ◽  
farima abdollahi-mamoudan ◽  
Xavier Maldague
Keyword(s):  
Infrared Thermography ◽  
Low Cost ◽  
Depth Estimation ◽  
Defect Depth ◽  
Fem Modeling ◽  
Flat Bottom ◽  
Pulsed Thermography ◽  
And Performance ◽  
Gated Recurrent Units ◽  
Non Destructive

Infrared thermography has already been proven to be a significant method in non-destructive evaluation since it gives information with immediacy, rapidity, and low cost. However, the thorniest issue for the wider application of IRT is quantification. In this work, we proposed a specific depth quantifying technique by employing the Gated Recurrent Units (GRU) in composite material samples via pulsed thermography (PT). Finite Element Method (FEM) modeling provides the economic examination of the response pulsed thermography. In this work, Carbon Fiber Reinforced Polymer (CFRP) specimens embedded with flat bottom holes are stimulated by a FEM modeling (COMSOL) with precisely controlled depth and geometrics of the defects. The GRU model automatically quantified the depth of defects presented in the stimulated CFRP material. The proposed method evaluated the accuracy and performance of synthetic CFRP data from FEM for defect depth predictions.

scholarly journals A Method of Defect Depth Estimation for Simulated Infrared Thermography Data with Deep Learning

2020 ◽  
Vol 10 (19) ◽  
pp. 6819 ◽  
Author(s):  
Qiang Fang ◽  
Xavier Maldague
Keyword(s):  
Infrared Thermography ◽  
Low Cost ◽  
Depth Estimation ◽  
Defect Depth ◽  
Fem Modeling ◽  
Flat Bottom ◽  
Pulsed Thermography ◽  
And Performance ◽  
Gated Recurrent Units ◽  
Non Destructive

Infrared thermography has already been proven to be a significant method in non-destructive evaluation since it gives information with immediacy, rapidity, and low cost. However, the thorniest issue for the wider application of IRT is quantification. In this work, we proposed a specific depth quantifying technique by employing the Gated Recurrent Units (GRUs) in composite material samples via pulsed thermography (PT). Finite Element Method (FEM) modeling provides the economic examination of the response pulsed thermography. In this work, Carbon Fiber Reinforced Polymer (CFRP) specimens embedded with flat bottom holes are stimulated by a FEM modeling (COMSOL) with precisely controlled depth and geometrics of the defects. The GRU model automatically quantified the depth of defects presented in the stimulated CFRP material. The proposed method evaluated the accuracy and performance of synthetic CFRP data from FEM for defect depth predictions.

A Combined Dimensional Kernel Method for Graph Classification

2017 ◽  
Vol 10 (3) ◽  
pp. 22-33
Author(s):  
Tiejun Cao
Keyword(s):  
Structural Information ◽  
Kernel Method ◽  
Three Dimensional ◽  
Graph Classification ◽  
Effective Technique ◽  
Quadratic Constraints ◽  
Molecular Chemistry ◽  
One Dimensional ◽  
Different Dimensions ◽  
Optimal Kernel

The data containing structural information is an important problem in the field of machine learning. Kernel methods is an effective technique for solving such problems. A combined dimension kernel method is proposed or graph classification in this paper. A two-dimensional kernel is first constructed in this method, and it incorporates one-dimensional information to characterize the molecular chemistry, and then a three-dimensional kernel is constructed based on the knowledge of molecular mechanics to characterize the physical properties of the molecule. On this basis, the kernel of different dimensions is integrated, and the quadratic programming problem with quadratic constraints is solved to obtain the optimal kernel combination. The experimental results show that the proposed method has better performance than the prior technology, and it outperforms the existing algorithm.

Approximate Optimal Initial Temperature Distribution From a Three Dimensional Model for Processes Requiring Coiling

2003 ◽  
Author(s):  
Nando Troyani ◽  
Orlando M. Ayala ◽  
Luis Montano
Keyword(s):  
Numerical Study ◽  
Separation Of Variables ◽  
Three Dimensional ◽  
Initial Distribution ◽  
Adaptive Finite Element ◽  
Three Dimensional Model ◽  
Dimensional Solution ◽  
Initial Temperature Distribution ◽  
One Dimensional ◽  
Numerical Strategy

A numerical strategy to determine an estimate to the optimal initial distribution of temperature for industrial processes requiring coiling of bars in hot metal rolling operations based on a three-dimensional mathematical model for the evolution of temperature in a shape changing domain is presented. The corresponding numerical solution is presented as well. The solution integrates a two dimensional geometrically adaptive finite element solution in the coiling plane for a shape changing domain with a finite difference one-dimensional solution in the widthwise direction of the bar using a novel numerical separation of variables strategy. Time is discretized according to a Crank-Nicolson type scheme. The results of a specific numerical study for the coiling of hot steel between the roughing stands and the finishing stands are presented.

Limits at $3 in a New Formulation for Path-Placement in the Workcells of Planar 3-R Robots

1995 ◽  
Vol 117 (3) ◽  
pp. 485-490 ◽  
Author(s):  
J. K. Davidson ◽  
N. A. Soman
Keyword(s):  
Dimensional Space ◽  
Three Dimensional ◽  
Solution Space ◽  
Graphical Form ◽  
Dimensional Solution ◽  
One Dimensional ◽  
Tool Paths ◽  
Planar Robot ◽  
New Formulation ◽  
Systematic Formulation

Excursion-limits at the third joint of a three-hinged planar robot are incorporated into a new systematic formulation for path-placement in which the three-dimensional solution-space is decomposed into a two-dimensional space of variables that strongly control the placement of the path and a one-dimensional space that is much less critical. The new formulation determines all acceptable positions for the first joint of the robot relative to the workpiece. All possible acceptable designs appear in a graphical form that can be readily visualized and be directly measured in a Cartesian frame of reference in the workcell. The method is extended to closed tool-paths, and the method is illustrated with practical examples.

Structure and function of neural networks in the retina

1988 ◽  
Vol 46 ◽  
pp. 26-27
Author(s):  
Peter Sterling
Keyword(s):  
Ganglion Cells ◽  
Three Dimensional ◽  
Structure And Function ◽  
Synaptic Connections ◽  
Visual Axis ◽  
One Dimensional ◽  
Cat Retina ◽  
Ultrathin Sections ◽  
And Function ◽  
Insight Into

The synaptic connections in cat retina that link photoreceptors to ganglion cells have been analyzed quantitatively. Our approach has been to prepare serial, ultrathin sections and photograph en montage at low magnification (˜2000X) in the electron microscope. Six series, 100-300 sections long, have been prepared over the last decade. They derive from different cats but always from the same region of retina, about one degree from the center of the visual axis. The material has been analyzed by reconstructing adjacent neurons in each array and then identifying systematically the synaptic connections between arrays. Most reconstructions were done manually by tracing the outlines of processes in successive sections onto acetate sheets aligned on a cartoonist's jig. The tracings were then digitized, stacked by computer, and printed with the hidden lines removed. The results have provided rather than the usual one-dimensional account of pathways, a three-dimensional account of circuits. From this has emerged insight into the functional architecture.

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