Dear All, I need to represent a hydraulic system into an equivalent mechanical (spring-mass-damper) system. But actually, they have reverse analogy in terms of flow resistance and stiffness.. meaning, Force=stiffness(k)*displacement; but Flowrate=(Pressure drop)/Flow resistance i.e., for series and parallel combinations, k and flow resistances will have reverse analogy additions.. I formed a stiffness matrix using concept of FE global elemental matrices assembly.. (1 dof @ each element nodes) - by considering the flow resistances of hydraulic circuit as spring stiffness directly... Similarly, i used the same matrix assembly process to determine flow coefficients matrix for hyd. circuit - but ending up with FLowrate = Pressure drop * Flow resistance (wrong relation) ie. Ab=X instead of AX=b So, how can i represent my flow matrix now?? Only after achieving this, I can proceed forward.. Also let me know that whether I can replace all co-efficients of stiffness matrix with 1/R terms.. Or should I have to take inverse of that matrix and perform the calculations.. Help me out in reaching the soln.. Ur ideas/suggestions r most welcome… Thanks in advance!!!