On the Improvement of Calibration Coefficients for Hole-Drilling Integral Method: Part I—Analysis of Calibration Coefficients Obtained by a 3-D FEM Model

Aoh, Jong-Ning; Wei, Chung-Sheng

doi:10.1115/1.1416685

Cited by 23 publications

(19 citation statements)

References 12 publications

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“…When a comparison is made with calibration coefficients obtained from other studies [8], similar trends and error rates were observed in the experimental calibration by different research works. It is therefore concluded that the coefficients calculated with the specified 3D FEM model are in agreement with the conventional coefficients of the incremental hole-drilling method.…”

Section: Determination Of Calibration Coefficientsmentioning

confidence: 62%

Effect of Plasticity on Residual Stresses Obtained by the Incremental Hole-drilling Method with 3D FEM Modelling

Puymbroeck

Nagy

Backer

2016

Residual Stresses 2016

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Abstract. The incremental hole-drilling method is used to determine high residual welding stresses in an orthotropic bridge deck. When comparing the measurement results with a theoretical residual stress distribution of an orthotropic steel deck, a large difference in sign and magnitude of the residual stress values is observed. These measurement results are presented in another paper [1]. The test method, specified in ASTM E837-13a only applies when the material behavior is linear-elastic. Relaxed-plastic strain can be detected in the region of the bored hole for the evaluation of high residual welding stresses. This plastic behavior can result in a significant error of the residual stresses. In this paper, the hole-drilling procedure is simulated and the effect of plasticity on the determination of residual stresses is studied with three-dimensional finite element modelling. The calculation software Siemens NX 9.0 is used to simulate the hole-drilling procedure with both linearelastic and elastic-plastic material behavior. First, a 3D model is set up for uniform in-depth residual stress fields with a linear-elastic material behavior to determine the calibration coefficients. The same model is used to determine similar calibration coefficients but this time with a simplistic model of material plasticity. The effect of plasticity on the uniform in-depth residual stresses is determined. The residual stresses obtained under the assumption that the material behavior is linear-elastic are an overestimation. In future research, residual strains for non-uniform in-depth residual stresses can also be studied with similar models. This will result in a more accurate determination of the residual weld stresses present in bridge constructions. IntroductionThe incremental hole-drilling method is widely used for measuring residual stresses in steel components. Plastic relaxed strain can be induced in the region of the borehole. Since this test method only applies when the material behavior remains linear-elastic, significant errors can be introduced by this plastic behavior during the determination of residual stresses [2]. In this paper, the effect of plasticity on the determination of residual stresses for uniform in-depth residual stresses is studied.

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Section: Determination Of Calibration Coefficientsmentioning

confidence: 62%

Effect of Plasticity on Residual Stresses Obtained by the Incremental Hole-drilling Method with 3D FEM Modelling

Puymbroeck

Nagy

Backer

2016

Residual Stresses 2016

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“…Using Hooke's law with plane stress approximation, the relieved radial strains at node ( , ), can be computed as: For the more complex case of a blind-hole, used in "thick" specimens (as it is the case for the rail application at hand), the relieved radial strain can be formally expressed by Eq. (4), with appropriate values for the calibration constants A and B (or ̅ and ̅ in most relevant literature) that are determined from experiments 6 and/or finite element models [7][8][9][10] . In typical finite element analysis, a structure under hydrostatic ( = ) and deviatoric ( = − ) stress state can be simulated to compute ̅ and ̅ , respectively.…”

Section: Theoretical Backgroundmentioning

confidence: 99%

Thermal stress measurement in continuous welded rails using the hole-drilling method

2016

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The absence of expansion joints in Continuous Welded Rail (CWR) has created the need for the railroad industry to determine the in-situ level of thermal stresses so as to prevent train accidents caused by rail buckling in hot weather and by rail breakage in cold weather. The development of non-destructive or semi-destructive methods for determining the level of thermal stresses in rails is today a high research priority.This study explores the known hole-drilling method as a possible solution to this problem. A new set of calibration coefficients to compute the relieved stress field with the finer hole depth increments was determined by a 3D Finite Element Analysis that modeled the entire hole geometry, including the mechanics of the hole bottom and walls. To compensate the residual stress components, a linear relationship was experimentally established between the longitudinal and the vertical residual stresses of two common sizes of rails, the 136RE and the 141RE, with statistical significance. This result was then utilized to isolate the longitudinal thermal stress component in hole-drilling tests conducted on the 136RE and 141RE thermally-loaded rails at the Large-scale CWR Test-bed of UCSD's Powell Research Laboratories. The results from the Test-bed showed that the hole-drilling procedure, with the appropriate residual stress compensation, can indeed estimate the in-situ thermal stresses to achieve a ±5F accuracy of Neutral Temperature determination with a 90% statistical confidence, which is the desired industry gold standard.

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“…En el caso de tensiones residuales no uniformes y siguiendo el método integral, Aoh y Wei investigaron los coeficientes de calibración y para un amplio rango de espesores [Aoh02]. Definieron los espesores adecuados para placas delgadas y gruesas y propusieron los coeficientes de calibración para ciertos casos que después validaron experimentalmente [Aoh03].…”

Section: Espesor De Las Probetasunclassified

“…Esta estrategia lleva a resultados más precisos que la corrección propuesta. Otros autores solo dan los coeficientes para un diámetro [Aoh02], [Nau13b] y se ofrecen para calcular el valor para otros diámetros bajo petición [Beghini00 10].…”

Section: Diámetro Del Orificiounclassified

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Desarrollo de métodos para la acotación de la incertidumbre en medidas de tensiones residuales en materiales metálicos tratados por LSP

Jiménez¹

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2017ii Planteamiento y resumen de la Tesis.La técnica de "Laser Shock Processing" o "Laser Peening" (LSP) es una tecnología que permite la mejora de las propiedades mecánicas de diversos materiales de interés estratégico en industrias tan variadas como la aeronáutica, la aeroespacial, la nuclear o la biomédica.El objetivo fundamental de la técnica LSP es la inducción de tensiones residuales de compresión en distintos materiales metálicos. Debido a las características del tratamiento, estas tensiones resultan estar distribuidas en zonas cercanas a la superficie de una manera no uniforme en profundidad. Resulta fundamental para la caracterización y desarrollo de la técnica LSP, por tanto, la medición de las tensiones residuales inducidas en estos materiales.Sin embargo, la medida de tensiones residuales es, independientemente del método elegido para ello, una tarea muy compleja, pues estas se distribuyen en el interior del material tratado.Existen principalmente dos técnicas de medida de tensiones residuales: las basadas en la difracción y las basadas en la relajación de tensiones. El CLUPM cuenta con la técnica del taladro incremental con rosetas de galgas extensométricas, estandarizado en la Norma ASTM E837-13. El taladro incremental es una técnica de relajación de tensiones cuyas principales ventajas son que provoca un daño muy localizado, que permite medir de forma más o menos rápida y sencilla hasta profundidades de 1-2 mm y que cuenta con un coste de equipamiento y consumibles muy inferior al de otras técnicas.Esta Tesis Doctoral se centra en la mejora de la técnica de medida de tensiones residuales no uniformes en profundidad mediante el método del taladro incremental con rosetas de galgas extensométricas. En concreto pretende desarrollar una metodología adecuada para el cálculo y la acotación de incertidumbres, la optimización de las distribuciones de puntos de cálculo de las tensiones residuales y la aplicación de la Norma ASTM E837-13 en la estimación de la incertidumbre.También pretende desarrollar modelos y estrategias para la corrección de las desviaciones que son muy influyentes en la decodificación de las tensiones residuales. Estas desviaciones son principalmente, la excentricidad del orificio (diferencia entre la posición teórica y real del orificio) y la geometría real del mismo (desviaciones con respecto a la idealidad geométrica considerada en los modelos de Elementos Finitos).La estructuración de la Tesis responde al desarrollo temporal de la misma. La figura 1 muestra un esquema de la estructura.En el capítulo 1 se presenta una introducción a las tensiones residuales en materiales metálicos y a la técnica LSP desde un punto de vista descriptivo.iii El capítulo 2 revisa los métodos existentes de medida de tensiones residuales y presenta las ventajas y desventajas de cada uno de ellos. También justifica la elección del método del taladro incremental en el CLUPM.En el capítulo 3 se describe detalladamente el método del taladro incremental, incluyendo su evolución histórica, los principios y teor...

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On the Improvement of Calibration Coefficients for Hole-Drilling Integral Method: Part I—Analysis of Calibration Coefficients Obtained by a 3-D FEM Model

Cited by 23 publications

References 12 publications

Effect of Plasticity on Residual Stresses Obtained by the Incremental Hole-drilling Method with 3D FEM Modelling

Effect of Plasticity on Residual Stresses Obtained by the Incremental Hole-drilling Method with 3D FEM Modelling

Thermal stress measurement in continuous welded rails using the hole-drilling method

Desarrollo de métodos para la acotación de la incertidumbre en medidas de tensiones residuales en materiales metálicos tratados por LSP

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