cylindrical tank tutorial

8/9/2019 Cylindrical Tank Tutorial

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How to Construct and Analyze a Cylindrical tank in Autodesk

PART I: Creating your tank

1)

Open Autodesk Inventor Fusion 2013

2)

Click New

3)

HomeSketchNew SketchSelect XY plane4)

SketchCenter-Radius CircleSelect (0, 0) as your center pointenter outer radius of tank

click enter until circle changes color

5)

Select the circle. Make sure to click inside the perimeter of the circle instead of selecting the

edge.6)

An extrude icon will pop up. Select extrude. Enter inside height of tank. Double click Enter


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7)

SketchCenter-Radius CircleSelect the middle of the top of the tank as the center-->Enter in

the inner radius of your tankClick Enter twice

8)

Select the inside circleextrudeenter the negative value of your tanks height to cut through


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9)

SketchCenter-Radius CircleDrag mouse to the upper rim of the tank and hold shift to lock

sketch planeSelect the center point as the center of circledrag radius until it locks with the

outer edgeEsc

10)

Hold down shift and select both the inner and outer circlesextrudeenter thickness for your

roof slabEnter 2xrepeat for the bottom of the tank


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At this point you should have a hollow, symmetrical cylinder that you cannot see the inside of.

Save the part and Select Simulation Mechanical in the Home tab. This will open Autodesk

Multiphysics, allowing you to stress and analyze your tank.


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PART II: Loading your Tank

1)

Once Multiphysics opens, it will prompt you to choose analysis type. Select the default

Static Stress with Linear Material Models

2)

In the FEA editor column on the left of the screen, right click Element Type under Part 1

and select Brick. Edit Element DefinitionMidside NodesIncludedOK

3)

Right Click MaterialConcreteSelect the concrete strength you prefer or alter its

conditions

4)

Go to the Mesh tab3D Mesh SettingsMesh Type= SolidMesh Size= approximately

70%Mesh Model


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5)

In the left panel, expand the surfaces tab and make invisible the outside of the tank by

holding control and selecting surfaces 1,2,4,5,6, right-clicking and unchecking visibility. This

should leave just the inside of the tank visible.

6)

Select the inside surface of the tankRight ClickAddSurface hydrostatic Pressure


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7)

Enter the fluid density of water (62.4 lbf/ft^3), Select the Z button in Fluid Depth Direction

(V), and enter the coordinates of the point that would lie on the top of the water in your

tank. For this tutorial we used X=0, Y=inner radius of tank, Z=height of tank. Select OK

8)

Make the rest of the surfaces visible again


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9)

Constrain the bottom surface by selecting the bottom surfaceRight ClickAddSurface

General Constraint-->Fixed

10)

To add rebar, complete the following steps

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Select DrawLineUnclick Use as ConstructionSelect the location on the mesh where

you would like to add the rebar (The maximum hoop stress in a tank occurs approximately

1/4-1/3 up the height of the tank. This is the best place to reinforce with rebar).

12)

Unfortunately, the only way the lock the rebar into place while still staying attached to the

tank is to manually select each vertex in a horizontal line all the way around the tank. If you

skip nodes, the rebar wont lock itself to the tank there, causing irregularities in geometryand adding stress concentration.


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13)

Once youve created a line circling the tank, edit its properties in the left columnPart

2Element Type = BeamElement Definition=Inertial Properties of your

RebarMaterial=Edit values for your rebar

You may add as many bars of rebar as you want. For the purpose of this tutorial we will only

use one though.


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PART 3: Analyzing your tank

Your tank simulation is now ready to run. But first go to setupGravitySet for standard gravityOK

Select AnalysisRun Simulation

*The more refined your mesh size is, the longer itll take for Autodesk to simulation your tank. With the

mesh size of 70% we picked before, Autodesk should only take about a 1:30

It may be useful to add a slice plane to examine the inside of your tank

Select Results OptionsSlice planesAdd Slice planeYZ plane

You can also fool around with how the tank visually appears by going to ViewVisual Style

Personally I prefer shaded with mesh.

At this point its up to you how you would like to analyze your tank. Its important to notethat while

normally, Von Mises is a good determination of maximum stress in your part, it is not useful here

because of stress concentration at corners and connection points. Hoop stress is what youre most

concerned about in tanks. Either the YY or XX tensors will give a good approximation of hoop stress. To

find the stress the rebar alone undergoes, select the Beams and Trusses option in Result Contours


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It might also help to change the units to inches. Thus stress will appear in psi.

For this tutorial, the tank undergoes a maximum tensile stress of 3.5 psi and a maximum compressive

stress of 12 psi. Considering the yielding stress of concrete is over 100 psi, it is reasonable to conclude

that this tank will not come close to fracturing due to the hydrostatic loading from the water it contains.

This tutorial was created by:

Engineers Without Borders

Lehigh University ChapterProject Class, Tank Group, Fall 2012

For questions contact:

Zachary Pelli

B.S. Mechanical Engineering 2014

Lehigh University

203-223-4067

cylindrical tank tutorial

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