Thermoelastic determination of crack-tip coordinates in composites

Ju, Shen-Haw; Rowlands, R. E.

doi:10.1016/j.ijsolstr.2006.12.003

Cited by 8 publications

(3 citation statements)

References 15 publications

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“…Yoneyama et al 19 used the method of nonlinear least squares to evaluate SIFs and the crack‐tip coordinates for isotropic materials. Ju and Rowlands 20 demonstrated a linear search method to evaluate the crack‐tip coordinates of composites using measured temperatures. This section used a similar method as the above references to generate correct crack‐tip coordinates as well as the angle, ( b ), between the measurement and crack axes (Fig.…”

Section: Evaluation Of Crack‐tip Coordinates and Angle Bmentioning

confidence: 99%

Determination of SIFs, crack‐tip coordinates and crack angle of anisotropic materials

Chiu

Jhao

2009

Fatigue Fract Eng Mat Struct

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A B S T R A C T This paper investigates the accuracy of a numerical method incorporating an imagecorrelation experiment for finding the crack-tip coordinates, the axes of the measurement and the mixed-mode stress intensity factors (SIFs) of anisotropic materials. Finite element and experimental simulations in this paper indicate that the proposed linear search method incorporating Powell's method is considerably stable for finding the unknown crack-tip coordinates and measurement axes, even though the initial input is far away from the actual data. Moreover, the displacement field very near the crack tip is not necessary. In the experimental validation, the maximum SIF error of the image-correlation experiment is about 9%, which should be acceptable for the mixed-mode fracture problems. a = crack length of specimens A = a search angle to find angle b using the least-squares method b = angle between the global X -coordinate and the local x-coordinate (Fig. 1) [a] = compliance matrix (strain-stress relationship) C = cross-correlation coefficient defined in Eq. (37) D = the magnitude of a search distance to find crack-tip coordinates [D] and [E] = matrices obtained from Eqs (9) to (12) for finding displacement E 11 , E 22 = Young's modulus in the axes of material symmetry (axes 1 and 2 shown in Fig. 1) E a and E b = the errors of the crack-tip coordinates and angle b defined in Eq.(18) E k = the error in the SIFs defined in Eq. (19) f (x, y) = undeformed subset intensity values at selected points within the subset g(x * , y * ) = deformed subset intensity values at selected points within the subset G 12 = shear modulus in the axes of material symmetry [K] = least-squares matrix in Eq. (17) for finding {β} K I and K II = mode-I and mode-II stress intensity factors N = the number of displacement terms in Eq. (7) N xy = area of D by D divided by N xy by N xy lines to find the correct crack-tip coordinates N angle = angle A divided by N angle angles to find correct angle b p j and q j ( j = 1,2) = material parameters calculated from Eq. (3) SHJ is a professor and CYC and BJJ are students.

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Section: Evaluation Of Crack‐tip Coordinates and Angle Bmentioning

confidence: 99%

Determination of SIFs, crack‐tip coordinates and crack angle of anisotropic materials

Chiu

Jhao

2009

Fatigue Fract Eng Mat Struct

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“…Using a camera in the 3-5 um (MWIR) wavelength range with an InSb detector, it is possible to detect events with microsecond integration times. This can be used to detect the occurrence of fast events, for example, Lüders bands [1][2][3], when synchronizing the camera with exciting harmonic loading events, which is useful in thermoelastic analysis (TSA) [4,5], in determining the dissipative energy estimation in fatigue tests [6,7,8], determining crack size [9], in the analysis of vibration and determination of resonance frequencies and modal shapes [10,11].…”

Section: Introductionmentioning

confidence: 99%

Processing of Results From a Thermal Fem Analysis Using the Lock-in Method and Comparison With Experiment

Štalmach¹,

Dekýš²,

Novák³

et al. 2019

SJSUT.ST

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This article dealt with the comparison of results obtained from an experiment and from the numerical thermal FEM analysis. Sample with defects were printed on a 3D printer. A thermal wave from the halogen lamp to excite the front surface of the sample was used in the next step and the response was measured by a thermal camera. After processing the data in the software DisplayIMG, a phase image was created representing the 2D image of the material at a certain depth under the surface of the model. Lock-in method was applied to the results from the numerical thermal FEM analysis and the phase image was created. The programs code were created in MATLAB for a 4 points, multiple points and differential lockin method which were compared with the results from the experiment.

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“…The beginnings and early development of the TSA were reviewed by Stanley [8]. There are rapid and continuing advances and new applications for the TSA both in the theoretical research and the engineering applications [9][10][11][12]. A review of the TAS and its latest developments has been presented by Greene et al [13].…”

Section: Introductionmentioning

confidence: 99%

A thermography-based approach for structural analysis and fatigue evaluation

Wang

Crupi

Guo

et al. 2011

Proceedings of the Institution of Mechanical Engineers, Part C:

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The infrared thermography has been developed for Non-Destructive Testing (NDT), stress analysis, and in the last 10 years for metal fatigue assessment. The present research enables to realize these different research objectives all together thanks to an innovative experimental procedure, which includes NDT by lock-in thermography, thermoelastic stress analysis, and fatigue parameters assessment by Rapid Thermographic Method (RTM). The developed procedure has been performed on a set of hole-notched specimens, achieving good results and predictions in a relatively short time. Moreover, the fatigue strength reduction coefficients of the specimens were determined by RTM. This thermography-based approach is dedicated for structural analysis and fatigue evaluation; it is an interesting attempt to apply different thermographic methods to a common research topic.

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Thermoelastic determination of crack-tip coordinates in composites

Cited by 8 publications

References 15 publications

Determination of SIFs, crack‐tip coordinates and crack angle of anisotropic materials

Determination of SIFs, crack‐tip coordinates and crack angle of anisotropic materials

Processing of Results From a Thermal Fem Analysis Using the Lock-in Method and Comparison With Experiment

A thermography-based approach for structural analysis and fatigue evaluation

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