Finite Element Analysis of a Propped Cantilever Beam

Instructor: Professor James Sherwood

Programs Utilized: FEMAP 10.0.2 and ABAQUS 6.11-2

Original tutorial by: Ching-Pei Liang (May 1998)

Updated February 2012

Problem Description:

This tutorial shows how to build and analyze the propped cantilever beam shown in Fig. 1. The pre- and postprocessing program is FEMAP 10.0.2, and ABAQUS 6.9-2 is used for the analysis. Three different loads are considered:

Material: AISI 4340 Steel Load case 1: Distributed Load case 2: Lumped Load case 3: Consistent

Fig. 1 Schematic of beam dimensions and loading

Build The Models in FEMAP

Creating The Geometry

Start FEMAP (or if you have already work in FEMAP, select File New to begin a new modeling session.)

Select Geometry Curve-Line Project Points o Enter the first point X=0, Y=0, Z=0, o Click OK. o Enter the second point X=100, Y=0, Z=0, o Click OK. o Click Cancel to end this command. o Select View Autoscale All (or you can do Shift+F7) o You should see a line in the x-y plane (Fig 1)

Fig. 1 Two points connected by a line

Defining I-Beam Material and Section Property

Select Model Material , o Click Load... , o Use the mouse to select AISI 4130 Steel , o Click OK. o Click OK to create the material. o Press Cancel to end creation of the material definitions.

Select Model Property ,

o (Step A) Use key (or mouse) to move to the Title field and enter, e.g., I-Beam .

o Click the down arrow next to the Material box, o (Step C) Choose 1..AISI 4130 Steel. o Click Elem/Property Type , o Select Beam , o Click Formulation, o Under the ABAQUS / MSCMARC / Ansys Options, hit the down

arrow and choose 2..Cubic (Euler-Bernoulli) Press OK o (Step E) Click OK.

o In the Define Property - BEAM Element Type popup window, click Shape ,

o Click the down arrow next to the Shape box, o Choose I Beam or Wide Flange (W) Section , o Use the key or the mouse to move to the next input field

box, o Enter H = 3 , Width, Top = 5 , Width, Bottom = 5 , Thick, Top = 1 ,

Thick, Bottom = 1, Thickness = 0.5, o Click Draw Section to see the cross section of the beam just

defined, o Under Orientation Direction, choose Up (Fig. 2)

Fig. 2 Cross section definition

o Click OK in the Cross Section Definition popup window. o Notice that several of the boxes in the Define Property - BEAM

Element Type now have nonzero values, e.g., Area and Moment of Inertia, as shown in Fig. 3.

o Click OK. o Click Cancel to end creation of property definitions.

Fig. 3 Define Property - BEAM Element Type popup window

Hint: If a property (or material) is used very often, you can save it so you do not have to create it every time. Also, you can delete some properties (or materials) which you will not use.

o To save a property: After (STEP E), click Save and click Yes, then continue with

the following steps.

o To use an exiting property: Skip (STEP A) , After (STEP C), click Load, Choose the property you want, Click OK.

o To delete a property:

Select Delete Library Property... Choose the property you want to delete Click OK. Click Yes.

Hint: For using an existing material, saving a material or deleting a material, you would do similar actions.

Generation of Nodes and Elements

Select Mesh Mesh Control Size Along Curve , o This command will setup the locations for the nodes and elements,

but does not create them. o Use the mouse to select the curve, o Click OK. o Under Mesh Size, choose Number of Elements, and enter 16 . o Under Node Spacing, choose Equal and Parametric, o Click OK. o Click Cancel to end this command.

Select Mesh Geometry Curve , o This command will create the nodes and elements. o Use the mouse to select the curve, o Click OK. o Click the down arrow on Property , o Choose 1.. I-beam. o Under Generate, choose Elements and Nodes . o Click OK. o To Define Element Orientation Vector click Methods^, o Choose Global Axis, o Choose the Positive and Y Axis options. o Click OK.

Note: This Element Orientation Vector defines the orientation of the beam cross section in the reference frame. It is very important to be sure that the beam is bending about the proper axis in space.

Loading and Constraining the Model

Select Model Constraint Set , o Enter Title for Constraint Set 1, e.g., Boundary Condition. o Click OK to create the constraint set.

Select Model Constraint Nodal , o Use the mouse to select the node on the end of left-hand side, o Click OK. o Click Fixed (which will fix all six DOFs, i.e. clamp condition), o Click OK to fix the left end of the beam (Fig. 4).

Fig. 4 Defining a clamped (Fixed) boundary condition

o Use the mouse to select the node on the end of the right-hand side, o Click OK. o Click Pinned and click OK when done. o Click Cancel to end creation of the nodal constraints. o You will now see numbers at each of these nodes describing what

DOFs are defined to be zero.

(1=Tx, 2=Ty, 3=Tz, 4=x, 5=y and 6=z) Thus, 123456 at left node show that all DOFs are set to zero and 123 at the right node show that all translations are zero. (Fig. 5)

Fig. 5 BCs shown on the beam

Select Model Load Set , o Enter a Title for load set 1, for example, Distributed, o Click OK to create load set 1.

Select Model Load On Curve , o Use the mouse to select the curve, o Click OK. o Set the load type to Force Per Length (as in a distributed load), o enter -10 in the FY field. o Uncheck FX and FZ.

Fig. 7 Creating the distributed load

o Click OK. o Press Cancel to terminate creation of loads. o Notice that the distributed load appears on the beam (Fig. 8)

Fig. 8 Beam showing 10 lb/in distributed load

Select Model Load Set , o Enter 2 in the ID box. o Enter Title for load set 2, for example, Lumped. o Click OK to create load set 2.

Select View Autoscale All to see the current load set you are

creating.

Select Model Load Nodal , o Hold key while dragging the mouse to select all the nodes

except the two end nodes by using Window, o Click OK.

o Set the load type to Force, o enter -10*100/16 in the FY field. o Uncheck FX and FZ. o Click OK. o Click Cancel to terminate creation of loads. o You should now see a force of 62.5 lbs on each of the interior

nodes (Fig. 9).

Fig. 9 The beam loaded at each node (Lumped Load)

Select Model Load Set , o Enter Title for load set 3, e.g., Consistent. o Change the ID to 3. o Click OK to create load set 3.

Select View Autoscale All (or Shit+F7) to see the current load set you are creating.

Select Model Load Nodal , o Hold the key while using the mouse to select all nodes

expect two end nodes by using Window, o Click OK. o Set the load type to Force, o Enter -10*100/16 in the FY field. o Uncheck FX and FZ. o Click OK. o Use the mouse to select the node on the end of right hand side, i.e.

the pinned node. o Click OK. o Set the load type to Moment, o enter 10*100*100/12/16/16 in the MZ field. The concentrated

moment is equal to qL2/12, where q is the distributed load per inch and L is the effective length of a beam element, L=100/16 in.

o Uncheck MX and MY. o Click OK. o Click Cancel to terminate creation of loads. (Fig. 10)

Fig. 10 Consistent loading depicted in FEMAP

Select File Save As to save your file. Enter a file name, e.g. beam.MOD Click Save Be sure to remember the drive and directory where the file is saved.

Hint: To delete a load set:

o Select Delete Model Load Set o Choose the load sets you want to delete, click OK, o Click Yes.

Similar steps can be done to delete Constraint sets.

Export Analysis Model

Select File Export Analysis Model (or Control + T) o Select Create/Edit Set (Fig. 11)

Fig. 11 Export method

o Choose New o Enter a title, e.g. Beam Study o Choose 16..ABAQUS, o Confirm that the Analysis Type is set to 1..Static, then select Next o In the ABAQUS Model Options window, choose, Next o In the Master Requests and Conditions, click Next

o In the ABAQUS Step Options, click Next o In the Boundary Conditions window, click on the down arrow in the

Loads line, and select 1..Distributed, then click Next o In the Output Requests window (Fig. 12), click OK.

Fig. 12 Output Request window

o The Analysis Set Manager appears. Expand the tress by clicking on the + buttonsexcept the Options +. You will see a window as given in Fig. 13.

Fig. 13 Analysis Set Manager

o Click Done. o Click OK. o In the "Save As popup Window, Enter the filename, e.g., ab_ib16,

then press Save. Be sure to remember where you saved the INP file.

Solve in FE Program

ABAQUS: o Open an "ABAQUS Command" window by doing "START > All

Programs > ABAQUS 6.9-2 > ABAQUS Command" o Go to the directory where you saved your *.inp file (Fig. 14)

Fig. 14 Directory with INP file

o At the DOS prompt, type "abaqus inter j=filename " , do not include the ".inp" extension. For example:

D:\22.513\Tutorials\Beam_Example> abaqus inter j=ab_ib16

Fig. 15 Running the model

Postprocessing in FEMAP

Reading in Results

Select File Import Analysis Results Choose ABAQUS and click OK. Enter Filename, for example, ab_ib16, and click Open. Click Yes to begin reading results file.

Postprocessing

Select View Select (F5) o Under Model Style, choose Draw Model, o Under Deformed Style, choose Deform, o Under Contour Style, Choose None-Model Only, o Click Deformed and Contour Data o Under Data Selection, choose 1..Displacement for Category o Choose 0..Value or Magnitude for Type. o Under Output Set choose1..Step 1, Inc1. o Under Output Vectors, choose 3..Y Translation. o Click OK when done. o Click OK. o Your result should look similar to Fig. 16

Fig. 16 Deformed and undeformed shapes superimposed in FEMAP

Select View Select o Under XY Style, choose XY vs ID, o Click XY Data o Under Data Selection, choose 1.Displacement for Category and

choose 0..Value or Magnitude for Type. o Under Curve, choose 1 o Under Output Set, choose the output set that you want to be draw

as curve 1. o Under Output Vectors, choose 3..Y Translation. o Click OK. o Click OK. o You will see a plot of Node ID vs. Y-translation as shown in Fig. 17.

Fig. 17 Plot of Node ID vs. Y-translation

Select List Output XY Plot o The data associated with the XY Plot will appear in the Messages

Window (See Fig. 18).

Fig. 18 FEMAP Messages window

To run another load set, o First get back to the model of the beam, Window New Window o In Window Layout, choose I and click OK o The model of the beam should now appear o Choose File Export Analysis Model o In the Export Method popup window, click Create/Edit Set o Expand the tree by clicking on the + sign

Fig. 19 Analysis Set Manager

o Double Click on Loads: 1..Distributed o In the Boundary Coditions window, choose another load, e.g.

2..Lumped o Click OK o Click Done o Click OK o Now save and run the next model and repeat the postprocessing

steps.