Are there any examples of an MSUP transient dynamic analysis? I cannot
get my acceleration load to have any effect in the results.
Yes, please see the ANSYS 9.0 springmass example below (and attached). It is important to note how the loads are applied. In this model, the gravity (acceleration) load is specified in the modal analysis and then applied via a load vector with the LVSCALE command. An additional force is applied in the second transient load step, but this force should also be initialized as zero in the preceding static load step. If the force were not applied, then the mass would stay at rest in the second load step after reaching static equilibrium in the first load step. This allows static analyses to be run as MSUP transients. = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = fini /clear /TITLE, MSUP Transient Example /plopts,info,1 /view,,1,2,3 /PREP7 ET,1,MASS21,,,2 ! 3D mass with no rotary inertia R,1,10.0 ! mass (10.0 Kg) ET,2,COMBIN14,,3 ! 1D longitudinal springdamper (UZ DOF) R,2,100.0 ! spring constant (100.0 N / meter) N,1,0,0,0 N,2,0,0,0 ! coincident node ... TYPE,1 REAL,1 E,1 ! mass element at node 1 TYPE,2 REAL,2 E,2,1 ! spring element from node 2 to node 1 eplot fini /SOLU ANTYPE,MODAL MODOPT,LANB,3 MXPAND,3,,,yes OUTRES,ALL,ALL ACEL,0,0,9.8 ! include base acceleration in load vector D,2,ALL,0.0 ! fix one end SOLVE save fini /solu ANTYPE,TRANS TRNOPT,MSUP,3 ! MSUP transient TIME,0.0 ! initial static solution defaults to TIME=0 DELTIM,0.001 ! DELTIM may not be changed in subsequent load steps OUTRES,ALL,all acel,0,0,0 ! apply gravity via load vector only ... f,1,fz,0.0 ! introduce nodal force in first load step ... !!! LVSCALE,0! do not include gravity (no load vector) LVSCALE,1 ! initial load step for frontal solver static solution ! Resulting initial static displacement should be: ! ! X = F/K = ma/K = (10.0 Kg)(9.8 m/sec^2)/(100 N/m) = 0.98 meters kbc,1 ! stepapply loads solve save time,1.0 ! DELTIM cannot be changed ... already set ... !!! LVSCALE,0 ! do not include gravity (no load vector) LVSCALE,1 ! gravity via load vector = 9.8 m/sec^2 f,1,fz,150.0 ! a = f/m = 150 N / 10 kg = 15.0 m/sec^2 (initially) kbc,1 ! stepapply loads solve save fini /POST26 numvar,200 file,file,rdsp NSOL,2,1,U,Z,uz2 ! displacement DERIV,3,2,1,,vz3 ! velocity DERIV,4,3,1,,az4 ! acceleration prvar,2,3,4 PLVAR,4 ! acceleration from force load only ... /eof ! Note: Acceleration from gravity is used to establish the initial ! static displacement (0.98 m). The stepapplied force in ! the second load step causes an initial acceleration per F=ma, ! but then the spring stiffness kicks in and alters the motion ! of this springmass system. If the force load is not applied ! (in the second load step), then the mass, which is in static ! equilibrium at the end of the first load step, will not move ! in the second load step (i.e., UZ = VZ = AZ = 0). For the ! model conditions shown above, the results are shown below. ***** ANSYS POST26 VARIABLE LISTING ***** TIME 1 UZ 3 DERI 4 DERI uz2 vz3 az4 0.0000 0.980000 0.371230E02 12.2155 0.10000E02 0.980004 0.943125E02 13.1436 0.20000E02 0.980019 0.225748E01 14.0716 0.30000E02 0.980049 0.375744E01 14.9994 0.40000E02 0.980094 0.525737E01 14.9990 0.50000E02 0.980154 0.675724E01 14.9984 0.60000E02 0.980229 0.825704E01 14.9976 0.70000E02 0.980319 0.975677E01 14.9967 0.80000E02 0.980424 0.112564 14.9957 0.90000E02 0.980544 0.127559 14.9945 0.10000E01 0.980679 0.142553 14.9931 0.11000E01 0.980829 0.157545 14.9916 . . . . . . . . . . . . 0.99600 3.97993 0.306791E01 14.9992 0.99700 3.97989 0.456781E01 14.9988 0.99800 3.97984 0.606767E01 14.9983 0.99900 3.97977 0.756747E01 14.9980 1.0000 3.97969 0.906727E01 14.9977 . 

