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Numerical investigation of crack orientation in the fretting fatigue of a flat rounded contact
, Article International Journal of Engineering, Transactions B: Applications ; Volume 23, Issue 3-4 , 2010 , Pages 223-232 ; 1728-144X (ISSN) ; Farrahi, G. H ; Sharif University of Technology
Materials and Energy Research Center
2010
Abstract
The growth of slant cracks by fretting fatigue of a half plane in contact with a flat rounded pad was studied. The mode I and mode II stress intensity factors for cracks of various lengths and directions were calculated using the semi-analytical method of the distribution of dislocations, and their cumulative effect on the crack growth was investigated using the strain energy density criterion. The results showed dominance of mode I fracture on crack growth, and based on the observation of strain energy density factor versus crack orientation, the results also suggest that depending on the crack length, the most critical orientations of cracks are at 0° to 20° outward the contact zone. Good...
Direct and indirect methods for determination of mode i fracture toughness using PFC2D
, Article Computers and Concrete ; Volume 20, Issue 1 , 2017 , Pages 39-47 ; 15988198 (ISSN) ; Haeri, H ; Shemirani, A. B ; Sharif University of Technology
Abstract
In this paper, mode I fracture toughness of rock was determined by direct and indirect methods using Particle Flow Code simulation. Direct methods are compaction tension (CT) test and hollow centre cracked quadratic sample (HCCQS). Indirect methods are notched Brazilian disk (NBD) specimen, the semi-circular bend (SCB) specimen, hollow centre cracked disc (HCCD), the single edge-notched round bar in bending (SENRBB) specimen and edge notched disk (END). It was determined that which one of indirect fracture toughness values is close to direct one. For this purpose, initially calibration of PFC was undertaken with respect to data obtained from Brazilian laboratory tests to ensure the...
Experimental and numerical investigation of the center-cracked horseshoe disk method for determining the mode I fracture toughness of rock-like material
, Article Rock Mechanics and Rock Engineering ; Volume 51, Issue 1 , 2018 , Pages 173-185 ; 07232632 (ISSN) ; Sarfarazi, V ; Yazdani, M ; Bagher Shemirani, A ; Hedayat, A ; Sharif University of Technology
Abstract
This paper presents a new procedure for determining the fracture toughness of rock-like specimens using the diametric compression test with the center-cracked horseshoe disk (CCHD) method. Using finite element analysis, a dimensionless stress intensity factor was obtained and a formula was rendered for determining mode I fracture toughness. To evaluate the accuracy of the measurement results produced by the CCHD method, fracture toughness experiments were conducted on the same rock-like material using the notched Brazilian disk (NBD) method. The CCHD tests were simulated using a two-dimensional particle flow code for validation of the experimental results, and a great agreement between the...