analysis of hydraulic stuctures in ansys

8/13/2019 ANALYSIS OF HYDRAULIC STUCTURES IN ANSYS

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ANALYSIS OF HYDRAULIC STUCTURES

IN ANSYSMuhammad

WAREM Ge


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WHAT IS FINITE ELEMENT ANALYSIS

For many engineering problems analytical solutions are not suitable becausecomplexity of the material properties, the boundary conditions and the structuitself.

The basis of the finite element method is the representation of a body or a stby an assemblage of subdivisions called finite elements.

The Finite Element Method translates partial differential equation problems in

of linear algebraic equations.

Stiffness matrix Nodal Displacement

Vector

Nodal Vector Force


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INTRODUCTION TO ANSYS

ANSYS is a general purpose finite element modeling package for numericalla wide variety of mechanical problems. These problems include: static/structural analysis (both linear and non-linear), heat transfer and fluid prob

well as acoustic and electromagnetic problems.

This tutorial will walk you through the static analysis of a simple concrete

dam. This will show you how you can create geometry, define element type

physical properties, mesh the model, conduct static analysis and

postprocessing.


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ANALYSIS IN ANSYS

Like in any numerical simulator, Performing Analysis in Ansys can also be dividthree major stages i.e.

Pre-Processing Analysis

Post-Processing


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PROCEDURE SUMMARY

Start Ansys

Specify Title

Define Element Types

Define material Properties

and Real Constants Generate Model Geometry

Mesh Geometry

Apply Loads and BoundaryConditions

Set Analysis Type (i.e. Static,Modal, Harmonic, FrequencyResponce...)

Set Analysis Preferencesaccordingly

Start Analysis

View and PContour Plots

Vector Plots

Plot Graphs

Etc...

Pre-processing Analysis Post-


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ANALYSIS IN ANSYS

AnalysisBoundaryConditions

MeshDefinition

MaterialProperties

ElementType

Geometry

Solid or Shell ?

Isotropic or anisotropic ?

Free or structured ?

Fixed, roller or free ? Loads.

Static, Modal, H


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GEOMETRY AND ELEMENT TYPE

The Geometry and element type have to be considered together.

Shell element are typically used for structure where the thickness is negligiblcompare to its length and width.

Nevertheless, a plate modeled with solid element would provide similar resudisadvantage lies in computation time.

Ansys provides a large choices of elements. In fact ANSYS element library co

of more than 100 different element formulations or types.

SOLID185SHELL281SHELL181


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DAM CROSS-SECTION


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SCHEMATIC

PARAMETERS

a = 55 mb = 41 m (Width)

c = 4 m (Service Road)

x = 0.70 (chosen from 0.7

y = 1

L = 400 m


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Geometry

Bottom to Top strategy

Keypoints

Lines Areas Volume

There are two way in which you can command ANSYS, one way is to us

and the other way is by using APDL code.


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MAIN GUI

Main Menu [Controls in which phase of Analysis you are]


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Geometry

Creating KP by GUI Creating KP by commands

K, NPT, X, Y, Z

Defines a keypoint.

k,1,0,0,0

k,2,41,0,0

k,3,4,51,0k,4,4,55,0

k,5,0,55,0


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Geometry In the same way, lines, areas and volumes can be gene

L, P1, P2,

Defines a line between

two kp.

L,1,2

L,2,3

L,3,4

L,4,5

L,5,1

AL, L1, L2, L3,

Generates an area

bounded by previously

defined lines.

AL,1,2,3,4,5

VOFFST, NAREA, DIST,

Generates a volume,

offset from a given area.

VOFFST,1,-1,


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1

2

ElementType

ET, ITYPE, Ename,

Defines a local element type from

the element library.

ET,1,SOLID185

ET,2,SOLID185

Or by just using command


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Material

Properties

Density_conc = 2250 !Density of Concrete in [kg/m^3]

EX_conc = 15e9 !Modulus of Elasticity for concrete [N

Poiss_conc=0.2 !Poisson's Ratio for concrete (0.1 - 0

Density_rock = 2640 !Density of Bottom rock in [kg/m^3]

EX_rock = 15e9 !Modulus of Elasticity for concrete [N

Poiss_rock=0.15 !Poisson's Ratio for concrete (0.1 - 0

desnity_water = 1000 ! [kg/m^3]

Creating Variables in APDL


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ElementType

MP, Lab, MAT, C0, C1, C2, C3, C4

Defines a linear material

property as a constant or a

function of temperature.

MP,EX,1,EX_conc

MP,DENS,1,Density_concMP,NUXY,1,Poiss_conc

MP,EX,2,EX_rockMP,DENS,2,Density_rock

MP,NUXY,2,Poiss_rock

1

3


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MeshDefinition

Structured Meshing Unstructured/Free Meshin

Two Types of Meshing


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MeshDefinition Unstructured Meshing on Dam sl

LESIZE, NL1, SIZE, ANGSIZ, NDIV, SPACE,

Specifies the divisions and spacing ratio on

unmeshed lines.

LESIZE,1,,,50

LESIZE,6,,,50

LESIZE,2,,,50

LESIZE,7,,,50

LESIZE,5,,,50LESIZE,10,,,50

LESIZE,3,,,10

LESIZE,8,,,10

LESIZE,4,,,10

LESIZE,9,,,10

LESIZE,11,,,2

LESIZE,12,,,2

LESIZE,13,,,2

LESIZE,14,,,2VMESH,ALL

Free Meshing


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MeshDefinition Structured Meshing on Dam slice

LESIZE, NL1, SIZE, ANGSIZ, NDIV, SPACE,

Specifies the divisions and spacing ratio on

unmeshed lines.

LESIZE,1,,,20

LESIZE,2,,,20

LESIZE,3,,,3

LESIZE,3,,,3

LESIZE,4,,,3

LESIZE,5,,,26

VOFFST,1,1, ,

VSWEEP,1,1,2

Structured Meshing


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Boundary

Conditions

Hydrostatic Pressure

Uplift Pressure

max_hydrostatic =desnity_water*9.81*A

max_hydrostaticBottom =desnity_water*9.81*B*0.7

SFGRAD,PRES,0,Y,0,-1*(max_hydrostatic/A)

nsel,s,loc,x,0 ! Select nodes for pressure

SF,ALL,PRES,max_hydrostatic ! Apply Pressure at all sel

nsel,s,loc,y,0 ! Select nodes for pressure

SFGRAD,PRES,0,x,0,-1*(max_hydrostaticBottom/B)

SF,ALL,PRES,max_hydrostaticBottom ! Apply Pressure at all sel


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Boundary

Conditions

Uplift Pressure Hydrostatic Pressure


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Boundary

Conditions

Fixed BC on bottom of Dam Slice

NSEL

NSEL, Type, Item, Comp, VMIN, VMAX, VINC

Selects a subset of nodes.

nsel,s,loc,y,0

D

D, NODE, Lab, VALUE, VALUE2, NEND, NINC,

Defines degree-of-freedom constraints at nodes.

D,all,,0,


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Analysis

Starting a Static Analysis

/SOL

ANTYPE,0

SOLVE1

3


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Post-

Processing

1

2


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Deformed Shape


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Deformation in X dir Von Mises St

Contour Plots


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Displacement Vectors

Vector Plots


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Vertical Distance vs Displacement

Graphical Plots


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http://goo.gl/LTSZLj

Download APDL File

T

analysis of hydraulic stuctures in ansys

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