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Subject: Mechanical Engineering × Author: Ansari, Gulfam Akhtar × End date: 2019 × Start date: 2010 ×
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    ThesisItemOpen Access
    Effects of randomly oriented secondary cracks on the fracture parameters in a rectangular plate under static loading
    (G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2019-08) Ansari, Gulfam Akhtar; Bisht, Neeraj
    In the present work, a numerical study using finite element is performed to investigate the effects of randomly oriented secondary cracks on the fracture parameters in a rectangular plate under static loading. Crack is damage that often occurs in members of structures and may cause the sudden serious failure of the structures. The effects of the presence of crack on fracture parameters like stress intensity factor and T-stress of specimen has been the subject of various investigations. However, the parametric studies like the effect of crack offset distance, crack size, orientation and number of crack present on the fracture parameters of the specimen are scarce in the literature. The finite element software ANSYS is used to simulate the fracture parameters. Numbers of studies were conducted to study the accuracy of ANSYS and the meshing parameters on which the accuracy depends. Two types of crack geometries were considered viz. parallel cracks and inclined cracks with different crack ratios. Also, the effect of several secondary cracks was studied. The presence of secondary cracks induced a shielding effect on the primary crack. The presence of secondary crack results in the development of mode II SIF. The mode mixing, however, was minimal and the mode II SIF was insignificant compared to mode I SIF. It is observed that when the cracks are closer to each other the shielding effect is high and as the cracks move away the shielding effect decreases. With the increase in inclination angle intensification effect is decreases. The shielding was also higher for a greater number of neighbouring cracks. Higher length of secondary cracks also increased the shielding effect. A correlation between SIF and T stress was also developed and it was seen that they are highly correlated. T stress can also be an important alternative fracture parameter to study crack interaction problems. Statistical analysis was performed to study the impact of various parameters in comparison to each other for all the geometries it was seen that the crack offset distance has a major influence on SIF compared to the crack ratios. Also, inclined cracks were seen to have a profound impact on SIF compared to parallel cracks. Multi-site damage is a common occurrence in aircraft and nuclear industries and the results of the study can contribute to accessing the structural integrity of the structure and estimate the in-service life of the component.