The material removal rate (MRR) and surface roughness (SR) are the key output measures of wire electrical discharge machining (WEDM). In this paper, the influence of several process parameters, such as the discharge current, pulse interval, open-circuit voltage and servo voltage on the MRR and SR of WEDM, were investigated. Experimental data were initially collected based on the Taguchi method of experimental design. Modelling was carried out using regression analysis and the analysis of variance techniques, and mathematical relationships between the parameters and their related outputs were developed and tested. A Tabu search algorithm was then used to minimize a weighted sum of the outputs that represent different measures of machining quality and determine the optimal set of parameters for any combination of the weighting factors. The final results present the optimized MRR and SR of the process and confirm the efficiency and abilities of the model.

To assess the dynamic behavior of monorail-bridge system, an innovative model of train-guideway interaction has been developed based on multibody dynamics and finite element simulation. A finite element model of guideway structure for a particular monorail system is built up using parametric design language, considering a specific length of straddle monorail line in three dimensions. Both straight and curved track geometries are modeled to simulate the actual bridge infrastructure. Flexible elements are adopted for the guideway beams consisting of reinforced concrete profiles to increase the accuracy of the numerical simulations in a more realistic way. The bridge model indeed, is simulated using a beam-frame structure of composite steel-concrete material. A multibody simulation of monorail vehicle is then introduced using the commercial multibody software MSC Adams. The three-dimensional multibody model of the monorail vehicle together with the bridge subassemblies is eventually implemented in multibody environment. The entire dynamic model of the vehicle-track system consists of all flexible and rigid body elements. Dynamic responses of the vehicle and bridge system are then extracted for different loading conditions. The proposed numerical model is validated using some dynamic simulation results of the system from the vehicle manufacturer in the selected case study. The model is further verified against several analytical and measurement results reported in the literature both for straight and curved track configurations. The result of dynamic simulations gives an overview about the dynamic forces and reactions that can appear in bridge structure due to the train movement.

A finite element (FE) model of the straight guideway bridge under monorail train has been built in this research in order to investigate dynamic interactions of the coupled system in the vertical and longitudinal direction. A limited length of the straddle monorail bridge including five continuous spans is modeled in three dimensions by using FE method. A 3D model of the monorail train system, built in the multibody analyzer MSC ADAMS, is assembled over the bridge. The entire model, consisting of the vehicle and bridge subsystems, is numerically analyzed by performing dynamic simulation in time domain. The braking forces between the train tires and guideway beams are activated in the analysis, in addition to the dead weights of the components and the train live loads. Dynamic forces in the tires are obtained for the case of the emergency braking in the system. The reaction forces, appeared in the bridge piers, are reported as the input forces for the purpose of the bridge design.

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