Understanding Nonlinear Analysis in ANSYS: A Tutorial for Scientists

[timewilltell]

hi,

I have some confusion for performing nonlinear analysis in ANSYS with NLGEOM... I was following the tutorial, the APDL is given below

/prep7 ! start preprocessor
/title,NonLinear Analysis of Cantilever Beam
k,1,0,0,0 ! define keypoints
k,2,5,0,0 ! 5" beam (length)
l,1,2 ! define line
et,1,beam3 ! Beam
r,1,0.03125,4.069e-5,0.125 ! area, izz, height of beam
mp,ex,1,30.0e6 ! Young's Modulus
mp,prxy,1,0.3 ! Poisson's ratio
esize,0.1 ! element size of 0.1"
lmesh,all ! mesh the line
finish ! stop preprocessor
/solu ! start solution phase
antype,static ! static analysis
nlgeom,on ! turn on non-linear geometry analysis
autots,on ! auto time stepping
nsubst,5,1000,1 ! Size of first substep=1/5 of the total load, max # substeps=1000, min # substeps=1
outres,all,all ! save results of all iterations
dk,1,all ! constrain all DOF on ground
fk,2,mz,-100 ! applied moment
solve
/post1
pldisp,1 ! display deformed mesh
PRNSOL,U,X ! lists horizontal deflections

the maximum displacement is 1.019

now without NLGEOM option that is just omitting these lines from above apdl prog

nlgeom,on ! turn on non-linear geometry analysis
autots,on ! auto time stepping
nsubst,5,1000,1 ! Size of first substep=1/5 of the total load, max # substeps=1000, min # substeps=1
outres,all,all ! save results of all iterations

maximum displacement is 1.024 , which should be less then the previous analysis with NLGEOM on

I don't understand this... kindly guide me where I am wrong

 

[Old student]

Hello,

"Nlgeom,on" takes into account nonlinearities in your analysis, i.e. the stiffness matrix is re-evaluated for each substep. The structure is more rigid (come back to school), consequently the displacement is reduced compared with the case "Nlgeom,off".

Rgds.

 

[hossam fouad]

hi ; my name is hossam
i want to any thing about luders hands
i have an exam tomorrow
anybody respond to me quiqly