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PostPosted: Tue Mar 01, 2016 3:25 am 
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Joined: Fri Feb 26, 2016 3:30 am
Posts: 3
My dear Sofistik friends

I wanted to model a moving mass crossing a bridge.I tried with the tool DYNA, unfortunately it seems that here only Forces can be considered (i.e. the dynamics off the bridge does not change and hence the change in mass is not considered). Then I tried ASE (moving train example), here it seems to work, however the issue is that I do not want to model the train/bridge interaction (it seems it is necessar to model a sprin).

My Question:
Is it possible to model a moving mass with the DYNA tool? Else is it possible to model a moving mass in ASE without any Spring (no vehicle/bridge interaction)?

Thank everyone for the help, I am getting desprete!!

My DYNA CODE (I tried to define a Mass instead of Force but did not succeed)::::

$ Defintion of all Variables
#DEFINE AREA=2 $ Cross section Area [m2]
#DEFINE E=32000 $ Youngs modulus [MPa]
#DEFINE G=10^10 $ Shear Modulus [MPa] (DELETE IF SHEAR DEFORMATION)
#DEFINE Iy=0.7813 $ Section Modulus [m4]
#DEFINE RHO=2500 $ Density of concrete [kg/m3]
$ DEFINITION of System Parameters
#DEFINE L=30 $ Length of the beam [m]
#DEFINE N=121 $ Number of Nodes=#N-1[-]

$ DEFINITION OF DYNAMIC CHARACTERISTICS
#DEFINE m=3 $ Number of Eigenvalues conisdered [-]
#DEFINE damp=0.02 $ Damping Coefficient (equal for all Eigenvalues) [-]

$ DEFINTION MOVING FORCE
#DEFINE P=100 $ (Static) Load of vehicle [kN]
#DEFINE V=30 $ Speed of moving force [m/s]
#DEFINE pi=3.14159265359
#DEFINE Dt=0.001 $ Time Step (Integration) [-]

+PROG AQUA urs:1

$ Definiton of Material
KOPF MATERIAL
NORM DC EN
SEIT UNIE 0
BETO NR 1 C 25 EC $(E)[N/mm2] GMOD $(G) GAM 25 RHO $(RHO)

$Definition of Cross Section
KOPF CROSS SECTION
QUER NR 1 MNR 1 A $(AREA) IY $(Iy)
ENDE

+PROG SOFIMSHA urs:2
KOPF SYSTEM
SYST 3D GDIV 10000 GDIR POSZ
KNOT (1,$(N)) 0.0,$(L) FIX PPMXMB $ Node 1 : Start Node
KNOT IMSH 1 $(N) TEIL ($(N)-1) $ Node #N: End Node
STAB FIT 1 $(N) QNR 1 DROT 0 $ #N-1 Elements
EDGE 10 FIT 1 $(N) $ Edge 10: to define boundary conditions....

KNOT 1000 X 0 Y 0 Z 0 FIX PYMM
KNOT 1001 X 0 Y 0 Z -1 FIX PYMM
FEDE 1101 KA 1000 KE 1001 CP 1000000
MASS NR 1001 MZ 100

ENDE

+PROG DYNA urs:3
KOPF EIGENVALUES
GRUP 0

EIGE $(m) $ Number of Eigenvalues
STEU STYP 1 $ Definition of Mass-/Stiffnessmatrix
MASS FAKT MX 0 MY 0 MZ 1 MXX 0 MYY 0 MZZ 0 MXY 0 MXZ 0 MYZ 0 MB 0
$ Set mass equal to 0 if eigenvalues are not of interest in that direction

LET#i 1
LOOP $(m)
MODD NR #i D $(damp)
LET#i #i+1
ENDLOOP
ENDE

+PROG SOFILOAD urs:5
KOPF FORCE FUNCTIONS
$ Loading of Vehicle is a superposition of several loadings
$ LF1 LF2 LF3
$ F(t)=P*[ 1 + a*Sin(wt) + b*Sin(wt)]

$ 2) 1st Moving Force
LF 1 BEZ STATIC PART
LZUG USER
LZPL P $(P) CONT

ENDE
+PROG DYNA urs:19.5
KOPF ANALYSIS
ECHO VOLL
LET#TIME $(L)/$(V)*2
LET#PAR 1.65 $ SAME DISPALCEMENT FOR #PAR = 1.65
LET#DELTA (3-2*(1-#par))/2
LET#BETA 0.25*((2-(1-#par))**2)
STEP N $(Dt)/#TIME DT #TIME THE 1.41

LF 1; CONT NR 10 V $(V) TMIN 0 ; AUSW U STYP ADD

LET#i 2
$ Generate Output
LOOP $(N)-2
HIST TYP U-Z VON #i DELT 1 LFSP 100+#i ERG DRUC DUMP UZ#i.txt
HIST TYP V-Z VON #i DELT 1 LFSP 100+#i ERG DRUC DUMP VZ#i.txt
HIST TYP A-Z VON #i DELT 1 LFSP 100+#i ERG DRUC DUMP AZ#i.txt
LET#i #i+1
ENDLOOP
$ SOMEHOW START NODE and END NUMBER can not be extracted

$ Hist: Output of u(t),v(t),a(t) etc.
$ Typ : U-Z, V-Z, A-Z...
$ Von...bis: Node Numbers you want to get the output
$ ERG:
$ LFSP: Saving Number

ENDE


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