Pavement roughness causes pavement stress fluctuation along the road. However, the dynamic effects were not taken into account in most pavement design and studies. To investigate the influences of roadway roughness on pavement stresses, this study developed a coupled system consisting of a quarter-car model and an equivalent lump pavement model. The coupled system also incorporated measured road profiles. By means of transfer function in frequency domain, the deflections and stresses of pavements were computed in seconds. The results were validated with Westergaard's solutions satisfactorily. It was found that the critical roughness, which might cause extreme responses, is related to the vehicle speed and suspension of vehicles. The maximum tension at the bottom of pavements also depends on the size of bump. In addition, the study demonstrates the correlation between roughness index, IRI, and ISO roughness classifications. It was also found that disturbance due to model boundary affects simulation results significantly.

This paper deals with the problem of the dynamic stress optimisation for manipulator robots. The maximum dynamic stress search is a challenging problem, insofar the dynamic stresses change in a very complex manner and they are strongly influenced by the payload, internal parameters of the robot, and instantaneous values of the articular variables (positions, velocities, and accelerations). This problem is solved using a hybrid simplex-genetic algorithm. This algorithm allows solving the dilemma of exploration vs. exploitation in the search space. A simulation study shows the greater performance of the proposed approach as compared to a classical approach of the configuration space inverse sweeping.