An examination of techniques based on two strain gages for the determination of stress intensity factor KI. (September 2020)

• Record Type: Journal Article
• Authors: Mejni, F.; Kanit, T.; Nianga, J.M.; Imad, A.
• Is Part Of: Engineering fracture mechanics. Volume 236(2020)
• Publication Date: 2020-09
• Subjects: Crack -- Stress intensity factor -- Mode I -- Finite element analysis -- Strain gage -- Gage location -- Valid region; Fracture mechanics -- Periodicals; Rupture, Mécanique de la -- Périodiques; Fracture mechanics; Periodicals; 620.112605
• DOI: 10.1016/j.engfracmech.2020.107191
• Languages: English
• ISSNs: 0013-7944

Abstract

Highlights: An examination of techniques based on two strain gages for the determination of K I is performed. A new formulation of the Dally and Sanford approach is presented. Valid region theory for the locations of two strain gages is demonstrated. Computation of the upper bound of the valid region is also substantiated. Locations of the strain gages outside the valid region are also discussed. The proposed technique gives accurate values of K I . 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) K I 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 K I 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 K I, when the technique of a single strain gage unable to provide the desired precision and accuracy of K I in some configurations.