Numerical study and experimental validation of the size effect of smooth and mode I cracked semi-circular bend specimens

Saeed Mousa; Mohammed Mutnbak; Abd-Allah M Saba; Amr A Abd-Elhady; Hossam El-Din M Sallam

doi:10.1038/s41598-023-34201-z

Numerical study and experimental validation of the size effect of smooth and mode I cracked semi-circular bend specimens

Sci Rep. 2023 May 10;13(1):7570. doi: 10.1038/s41598-023-34201-z.

Authors

Saeed Mousa¹, Mohammed Mutnbak², Abd-Allah M Saba², Amr A Abd-Elhady³, Hossam El-Din M Sallam⁴

Affiliations

¹ Mechanical Engineering Department, College of Engineering, Jazan University, 706, Jazan, Saudi Arabia.
² Civil Engineering Department, College of Engineering, Jazan University, 706, Jazan, Saudi Arabia.
³ Mechanical Design Department, Faculty of Engineering, Helwan University, Cairo, 11718, Egypt.
⁴ Materials Engineering Department, Zagazig University, Zagazig, 44519, Egypt. hem_sallam@zu.edu.eg.

Abstract

The edge-cracked semi-circular bend (SCB) specimen subjected to three-point bending loading is used in many applications to measure the fracture behavior of quasi-brittle materials. The main objective of the present work was to study the effect of the crack length to SCB specimen radius ratio (a/R), span to specimen diameter ratio (S/D), and specimen size on its flexural and mode I crack growth behavior. The contour integral method was implemented using the 3-D finite element method to determine the mode I stress intensity factor. In addition, high-strength concrete specimens were experimentally studied to validate the numerical results. The results show that the maximum compression stress is not sensitive to the S/D value, while the tensile stress is very sensitive. The value of S/D is the main parameter controlling the crack driving force (i.e., the crack mouth opening displacement (CMOD) and the normalized stress intensity factor, Y_I). For the same S/D, the SCB specimen diameter value change has a marginal effect on CMOD and Y_I. The specimen with S/D = 0.8 showed that it is the most compatible specimen with three-point bending test conditions, regardless of the SCB specimen size. A good agreement between the numerical and experimental results was achieved.