An examination of techniques based on two strain gages for the determination of stress intensity factor [formula omitted

Abstract

In this paper, Dally and Sanford [1] (DS) two strain gages technique (DS2) and a modified DS two strain gages technique (M_DS2) for accurate measurement of stress intensity factor (SIF) KI are studied. Accordingly, general finite element approaches are developed to estimate the extent of the radial locations of the strain gages in order to estimate the extent of the three- and four-term of the strain series proposed by DS. Also, to estimate the extent of validity of the proposed modified technique (M_DS2), which is a modification of the four-term strain series proposed by DS. A comparison between the results obtained by the technique of a single strain gage and the technique of two strain gages proposed by DS and the new technique is performed for four examples of configuration. Results of numerical examples show that the DS2 and M_DS2 can yield a highly accurate value of KI when the two strain gages are placed within the valid locations. Also, the results of numerical examples show that the above two strain gages techniques provide good solutions to ensure accurate measurement of KI, when the technique of a single strain gage unable to provide the desired precision and accuracy of KI in some configurations.