# Three Bar Mechanism # # References: # 1. MSC/DYNA verification manual # # Problem Description # # Three rods with length L make up a structure. The structure is given an inital velocity V # which sets the structure in rotation. # # # -> V -> V # o-------------o # | | # | | # | | # | | # O O # ^ ^ # # The rod elements are pinned to the ground, but have free rotation connections. # # Reference Results # # The analytical result for the structure are are as follows: # # X_displacement for node 2 and 3 = L * sin(t) # # Period time T = 2 * Pi * L / V = 6.283 # # # Results # # Impact perid is agrees well with theory # # # Engineering data # # Length L = 1.0 # Initial Velocity V = 1.0 # Young modulus E = 210.0 # Density rho = 1.0E-6 # Poissons ratio nu = 0.3 # Rod Diameter D = 1.12840 = sqrt(4/Pi) (Cross area = 1.0) # CONTROLS run from 0.00000 to 7 print every 0.5 step print tracker every 0.001 step MATERIALS OF TYPE ELASTIC mat_1 E = 210 RHO = 1.0E-6 NU = 0.3 NODES 1 x = 0.00000000 y = 0.00000000 z = 0.00000000 constraint = fixed 2 x = 0.00000000 y = 1.00000000 z = 0.00000000 constraint = vel 3 x = 1.00000000 y = 1.00000000 z = 0.00000000 constraint = vel 4 x = 1.00000000 y = 0.00000000 z = 0.00000000 constraint = fixed ELEMENTS OF TYPE rod_2 1 nodes = [1,2] D = 1.1284 material = mat_1 contact = off 2 nodes = [2,3] D = 1.1284 material = mat_1 contact = off 3 nodes = [3,4] D = 1.1284 material = mat_1 contact = off CONSTRAINTS OF TYPE boundary_condition vel ax = [0,0.0,1E-6,off,10,off] vx = [0,1.0,1E-6,off,10,off] az = 0 vz = 0 fixed ax = 0 ay = 0 az = 0 vx = 0 vy = 0 vz = 0 TRACKERS OF TYPE NODEDISPLACEMENT 1 node = [2] direction = x filename = Ver_11.trk target = [6.283,1E-3,0.0,1.0E-3]