چكيده به لاتين
In recent years, extensive research has been conducted using fracture mechanics on new materials such as elastomers and rubbers. The presence of stress concentration factors in elastomeric and rubbery materials can influence their performance and lead to a reduction in their service life. Therefore, presentation of a new criterion for prediction of fracture in this type of materials is recommended. Due to the geometric and nonlinear material behaviors of rubberlike materials, the use of previous criteria for brittle and quasi-brittle materials is limited and sometimes impossible. This research investigates a physical phenomenon exhibited by rubbery materials with high deformability and pre-existing crack during uniaxial tensile loading, named here as "crack removal" phase. In this condition, stress concentration effects diminish significantly after a certain period of time, the specimen behaves such that it has no crack, undergo nearly simple tensile state until final rupture.
A novel criterion for detecting the crack removal load and subsequently, predicting the fracture load is introduced for this kind of materials. To implement this criterion, only two experimental tests are required, highlighting the advantage of the proposed criterion: a simple tensile test on a dumbbell-shaped specimen and a fracture test on a cracked specimen. The results of experimental tests indicated that crack growth and fracture occurred in all specimens in the nearly horizontal path and perpendicular directions to the loading axis. Moreover, by comparing the experimental results for the crack removal load, it was observed that crack removal occurred for all tested crack lengths at 20 to 30 percent of the applied load. The comparison of the proposed criterion with experimental results indicated that the error obtained for the crack removal load and fracture load is less than 11.44% and the average error is less than 8%, demonstrating the high accuracy of the introduced criterion.
