Three-dimensional boundary element analysis of contact and fracture problems

A general purpose three dimensional boundary element method is developed for elastic solids. Emphasis is placed on the unique requirements of contact and fracture problems. In order to allow efficient and detailed calculations near the region of contact, special infinite elements that include the exact effects of infinite boundaries are developed. It is shown that these infinite elements can be used to accurately calculate contact stresses with very few elements. The effect of naturally occurring three dimensional defects on stresses and fatigue life is calculated. A void reduces the maximum allowable fatigue limit design pressure by 75 percent while a hard inclusion reduces it by 25 percent. The modified crack closure integral is used to accurately calculate the three-dimensional stress intensity factors. A multidomain approach is utilized for mixed mode cracks. In general the error of prediction of the stress intensity factors is within +/- 1.5 percent. Finally, the sliding blister field model of sliding micro indentation fracture is shown to give qualitative agreement with experimentally observed crack growth.