Lower-bound shakedown analysis of pavements by using the interior point method
Nguyen, An-Danh; Weichert, Dieter (Thesis advisor)
Aachen : Publikationsserver der RWTH Aachen University (2008)
Dissertation / PhD Thesis
Pavements fail in general not by sudden collapse but by gradual deterioration after a large number of loading cycles, in particular by rolling contact. Based on the lower-bound theorem by Melan, the shakedown load for pavements under cyclic rolling contact loading can be determined. The thesis is composed of three main parts. First, a method for the shakedown analysis of repeated sliding/rolling line contact as well as repeated stationary line and point contacts is introduced. The material is assumed to be rate-independent elastic-plastic. As yield conditions, the rounded Mohr-Coulomb, Tresca and von Mises yield criteria are used, assuming associated flow rules. The proposed numerical method is based on finite elements and the inherent optimization problem to determine the shakedown factors is solved with the interior point method. The results are compared with previous results. Secondly, Melan’s extended theorem of shakedown analysis for non-associated flow rules is introduced to take into account the non-associated behaviour in granular materials. Such shakedown analysis of non-associated plasticity flow are needed to be developed because internal friction and change of physical state defined by density and volume changes the plastic strain increment deviates from the normality of yield surface. Finally, using the simple cap model proposed by Sandler (1976)  and Bathe et al. (1980)  combined with the rounded Mohr-Coulomb, the bound on hydrostatic stress in triaxial condition has been introduced into the formulation of the shakedown problem.