The main intention of this research work is to study the derailment response of high speed railway vehicle (HSRV) cruising on a curved track. In previous research work, lower degree of freedom (DOF) has been considered for the derailment analysis which may not give more accurate results. Hence, a 31 DOF bondgraph model of HSRV has been developed which consist of carbody, two truck frames and two selfsame wheelsets for each truck frame. Vertical, lateral, roll, yaw and pitch motion are considered for carbody and bogie and except pitch motion all the other motion are considered for wheelsets. Non-linearities in terms of heuristic nonlinear creep model and flange contact has been employed to simulate the derailment response at high speed. The effect of vehicle speed running on a curved track was investigated for derailment quotient. The main aim of present research work to evaluate derailment quotient at the speed range of 150 kmph to 600 kmph for hard and soft suspension parameter. Derailment quotient has been calculated for both linear and nonlinear creep models and it is seen that DQ for linear model has a lower value compare to non linear creep. The major advantages of the proposed model are that, the presented model can actively predict the derailment of a railway vehicle, and also precisely determine the nonlinear critical hunting speeds.

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Inconel 825 is a prominent Ni-Fe-Cr based superalloy finds application in aerospace, defense, automotive, nuclear, marine industries. This article investigates ‘weld strength’ and ‘weld bead characteristics’ of Inconel 825 weld specimens welded using the gas tungsten arc welding (GTAW) process. The welding speed (V), welding current (I), gas flow rate (GFR) and arc length (N) are considered as GTAW parameter and their effect has been examined on the weld characteristics. Welding speed and welding current has been identified as the most influential factor on process characteristics; increased welding current combined with lower welding speed enhances the penetration (P) and ultimate tensile strength (UTS) of the weldments. To obtain a favorable parameters setting that satisfies both the criterion simultaneously i.e. maximizing weld strength for optimum weld bead geometry, a hybrid optimization approach employing desirability function coupled with grey relational analysis (DF-GRA) is proposed. Satisfying all the objectives simultaneously, the approach provides an optimum weld parameters setting of (I3−V1−GFR2−N1:120 A−180 mm/min−9 l/min−2 mm) resulting an improvement of 4.15 % in penetration (P), 5.12 % in front width (FW), 19.74 % in front height (FH), 1.29 % in ultimate tensile strength (UTS), and 2.9 % in percentage elongation (%E) on validation. Upon comparison, the algorithm outperforms the optimization results of both DF and GRA approach suggesting its robust nature. Overall, the DF-GRA hybrid approach is found simple and effective that includes the ignored robustness of the desirability approach.

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