Accurate determination of contact stresses in continuous mining cutters using variational inequalities

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There exist two major types of drilling in mining: exploration and/or production drilling. The former involves rotational crushing using diamond bits, while the latter involves percussive hammering using drill bits with multiple hardmetal or carbide inserts. In percussive hammering, the drilled holes are subsequently filled with explosives to blast loose the rock and/or ore body. Such a process requires stringent safety measures to protect the miners and surroundings, and as a result limits productivity and cost effectiveness. Therefore, a continuous mining system (CMS) would be most effective in exploration and/or production drilling. The road block has been the high hardness of the ground materials. The key component by far in CMS is the cutter head and tip. The cutter tip is subjected to very high contact stresses and heat. To prevent cutter tips from fracturing and spalling and wear, a thorough understanding of the resulting contact stresses is necessary. Hertz classical theory of contact is unsuitable because of its severe restrictions. In addition, current finite element codes rely on the use of contact elements that involve user-defined parameters, which have undesirable effects on the convergence and the accuracy of the solution.