Analysis of Undercarriage Frames of Railway Wagons

Undercarriages of railway wagons, are frames in horizontal planes, subjected to axial forces of very high magnitude and of impulsive nature during shunting operations. With the help of the assumptions used in beam bending theory, the stiffness matrix is developed, with six degrees-of-freedom for each joint. When an axial load of comparable amount is applied at buffers, the stiffness function is no longer a linear function of axial load. The axial force in a member may be either tension or compression, but the latter is usually of greater interest because of the possibility of buckling. The modified stiffness matrix for a general beam element is generated in terms of stiffness method is applied. In the second cycle, the axial forces in members, as obtained from the first cycle, are used to determine the modified stiffness matrix. The second cycle is then completed, using modified stiffness and fixed-end actions, and new values of axial forces are obtained. The processes repeated until two successive analysis yield approximately the same result.