Determining reliable edge isopachic data from interior thermoelastic measurements

Rauch, B. J.; Rowlands, R. E.

doi:10.1007/bf02326477

Cited by 17 publications

(9 citation statements)

References 10 publications

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“…However, all of these approaches require significant prior knowledge of the stress distribution and so are impractical for use with complex structural components. Similar work by Barone and Patterson [36], using a finite difference Laplacian approach, presents the same difficulties as the Rauch and Rowlands method [33].…”

Section: Review Of Surface Stress Separationmentioning

confidence: 94%

“…This approach is experimentally challenging due to the difficulty in measuring the harmonic at twice the loading frequency, and requires the capture of high quality data for the analysis to succeed. Recently, Rauch and Rowlands have also studied a uniaxially loaded tensile plate with a central hole and used a least-squares iteration with partial boundary information [33], filtering using a Laplacian solution [34], the incorporation of limited boundary information and a finite element simulation [35]. However, all of these approaches require significant prior knowledge of the stress distribution and so are impractical for use with complex structural components.…”

Section: Review Of Surface Stress Separationmentioning

confidence: 98%

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An Integrated Approach to the Separation of Principal Surface Stresses Using Combined Thermo-Photo-Elasticity

Greene

Patterson

2006

Exp Mech

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A new instrument capable of the full-field separation of principal stresses on the surface of a component is presented. The instrument combines the techniques of thermoelastic stress analysis and reflection photoelasticity in a single optical head, permitting the simultaneous capture of both data from the same point of view. A single strain witness coating is employed for the acquisition of both the thermoelastic and photoelastic data, which is both birefringent under applied stress conditions and opaque at the infrared wavelengths to which the thermoelastic analysis system is sensitive. This enables the combined technique to be performed continuously from the same surface during loading. The performance of the new instrument is validated in the analysis of a classical laboratory specimen of known geometry. Separated stress data from the experiment is compared to simulated data, demonstrating that the accuracy of the stress separation technique is comparable to that of the individual thermoelastic and photoelastic techniques, and it is concluded that combined thermo-photo-elasticity is a powerful tool for the experimental separation of principal surface stresses.

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Section: Review Of Surface Stress Separationmentioning

confidence: 94%

Section: Review Of Surface Stress Separationmentioning

confidence: 98%

An Integrated Approach to the Separation of Principal Surface Stresses Using Combined Thermo-Photo-Elasticity

Greene

Patterson

2006

Exp Mech

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“…The integer m of equations (5) is positive. The j 0 terms of equations (5) and related expressions contribute to rigid-body motion and are omitted here. In addition to satisfying the tractionfree conditions on the hole boundary Ã, the stresses and displacements of equations ( 1) and (2) associated with these stress functions Ö(ae 1 ) and Ø(ae 2 ) satisfy equilibrium and compatibility.…”

Section: Basic Equationsmentioning

confidence: 99%

Experimental determination of stress concentrations in orthotropic composites

Baek

Rowlands

1999

The Journal of Strain Analysis for Engineering Design

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Determining stress raisers necessitates accurate knowledge of the stresses on the edge of the geometric discontinuity. Recognizing difficulties in obtaining measured stresses at the edge of a hole or notch, the least-squares method, in conjunction with a Laurent series representation of the stress functions and local collocation, is used to evaluate reliable stresses on the boundary of holes in loaded composites from measured data away from the hole. Advantages over previous such hybrid analyses include the fact that few measured input data are required, that they can be arbitrarily located and that only a very few terms are needed in the stress function representation. The approach is illustrated for stress input as well as moire Â-measured displacements. Application to each of the three classes of orthotropy is deliberately addressed.

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“…Representative thermoelastic stress analyses, some of which supplemented TSA information with other measured data, are described [2–22]. Several of these approaches used complex variables in their stress functions and mapping techniques, but the current Airy stress function technique offers the convenience of real variables.…”

Section: Introductionmentioning

confidence: 99%

Separating Stresses Thermoelastically in a Central Circularly Perforated Plate Using an Airy Stress Function

Lin¹,

Matthys²,

Rowlands³

2009

Strain

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Thermoelastic stress analysis (TSA) is a contemporary full‐field, non‐contacting method of experimental stress analysis. In a cyclically loaded structure which experiences adiabatic and reversible conditions, the measured local change in temperature is proportional to the change in stress. Under isotropy, the technique measures information on the sum of the principal stresses. As engineering analyses often necessitate knowing the individual components of stress, additional experimental methods or information are frequently required to ‘separate the stresses’. The ability to evaluate individual stresses reliably in a uniaxially loaded finite plate with a central circular hole from TSA‐recorded information without supplementary experimental data is demonstrated here. Measured temperature data are combined with an Airy stress function and some limited traction‐free conditions. The present inverse technique does not presuppose knowledge of the external geometry or boundary conditions, overcomes the traditional difficulties of unreliable edge data, and reduces the number of coefficients needed by satisfying the traction‐free conditions analytically on the edge of the hole. Particular attention is paid to determining a realistic value for the needed number of Airy coefficients.

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Determining reliable edge isopachic data from interior thermoelastic measurements

Cited by 17 publications

References 10 publications

An Integrated Approach to the Separation of Principal Surface Stresses Using Combined Thermo-Photo-Elasticity

An Integrated Approach to the Separation of Principal Surface Stresses Using Combined Thermo-Photo-Elasticity

Experimental determination of stress concentrations in orthotropic composites

Separating Stresses Thermoelastically in a Central Circularly Perforated Plate Using an Airy Stress Function

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