Papers by Keyword: Crack Angle

Abstract: In this work, the effect of the prefabricated crack offset angle on the fracture toughness of the CT specimen was studied by means of the numerical simulation of tensile fracture. It is found that offset angle has a great influence on the fracture toughness of the CT specimen with a straight crack, and the effect is obvious when the bias angle is greater than 3 degrees. For the CT specimen with an oblique crack tip, with the increase of the bias angle of the crack tip, the J-integral value and the fracture toughness are not significantly changed. At the same time, as the angle increases, the stress applied load has more obvious influence on the crack tip stress field.

Abstract: Crack universally existing underground is an important kind of pores. In order to study the elastic wave propagation in fractured medium through experiment, a new method to make artificial core with certain cracks using oil well cement and camphor sheet or thin steel sheet is put forward. Geometric parameters of the crack, such as shape, size and aspect ratio, are approximately equal to that of camphor sheet or thin steel sheet. Using the thin steel sheet to make crack can be more easy and accurate to control the crack angle than using camphor sheet. The crack opening scales at millimeters. The aspect ratio of cracks formed by camphor sheet ranges from 1.4 to 8, and aspect ratio of cracks formed by thin steel sheet ranges from 2.5 to 70. This method is proved simple and feasible by experiment practice, which can provide artificial cores with certain crack for acoustic wave propagation study.

Abstract: The type of I-II compound crack in bridge deck pavement is most popular. Based on the theory of fracture mechanics the least equivalent stress method is put forward and used to study the problem of concrete cracks. The method could be used to determine the fracture angle of I-II compound crack. For the cracked deck pavement, the stress state could be determined by field test or numerical simulation method and then calculate the equivalent stress near the point by Matlab. The examples show that when the equivalent stress gets to the critical value the crack will develop along fracture angle which could be calculated from the least equivalent stress method. The theory value of fracture angle is basically accurate with the test one.