Three point bending: general contact and contact pairs

Strategic Simulation & Analysis Ltd

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T. 01608 811777 F. 01608811770

Three point bending: general contact and contact pairs.



T. 01608 811777 F. 01608811770 [email protected] W. www.ssanalysis.co.uk

Three point bending: general

contact and contact pairs.


[email protected] W. www.ssanalysis.co.uk

Three point bending: general contact and contact pairs.




1. Introduction The first exercise of this contact event will show you the two main approaches available in Abaqus to include interactions within your model: the contact and the contact pairMain difference among the two approaches is the way the contactFurthermore, there are other minorof the contact and some specific restrictions for each of the approaches. - General contact allows you to define contact in your entire model with only one-click and it is generally a very fast process - Contact pairs approach requires you to define a new interaction for each surface pair you want to include in the model. Thicomplicated and time-consuming if you have a large assembly. Howesometimes, it is the only option if you have for instance analytical surfaces in the model. In this example, a metallic beam undergo a three point bendingthree rigid tools. The model will be already preboundary conditions. Your onlytwo approaches provided by Abaqusdata.

2. Preliminaries - Double click on the file Cyou will already find a model called instance positioning in the assembly and the discretization of the parts. - The model (Figure 1) is actually to exploit the symmetry occurring in the Xof the analysis.

Figure 1. Assembly of the three point bending moment.




first exercise of this contact event will show you the two main approaches available in Abaqus to include interactions within your model: the general

contact pairs approaches. Main difference among the two approaches is the way the contact is defined.

other minor differences related to the numerical solution of the contact and some specific restrictions for each of the approaches.

allows you to define contact in your entire model with only and it is generally a very fast process.

approach requires you to define a new interaction for each pair you want to include in the model. This could become really

consuming if you have a large assembly. Howesometimes, it is the only option if you have for instance analytical surfaces in the

metallic beam modelled with plastic material properties will three point bending loading condition enforced through

he model will be already pre-defined in terms of geometry, meshing and only task will be to define the interactions

provided by Abaqus, run the analyses and post-process the

Contact1.cae, this will open an Abaqus database where a model called Model-GC including the geometric parts, the

instance positioning in the assembly and the discretization of the parts.

is actually a quarter of the model shown in the title page to exploit the symmetry occurring in the X-Y and Y-Z planes and reduce the cost



[email protected] W. www.ssanalysis.co.uk 2

first exercise of this contact event will show you the two main approaches general

is defined. the numerical solution

of the contact and some specific restrictions for each of the approaches.

allows you to define contact in your entire model with only

approach requires you to define a new interaction for each s could become really

consuming if you have a large assembly. However, sometimes, it is the only option if you have for instance analytical surfaces in the

with plastic material properties will loading condition enforced through contact with

defined in terms of geometry, meshing and define the interactions with the

process the

, this will open an Abaqus database where metric parts, the

instance positioning in the assembly and the discretization of the parts.

shown in the title page and reduce the cost





3. Material and section - Start to define the material propertiesIn the Edit material dialog box, Mechanical ��Elasticity ��Enter 210e3 MPa as Young’s modulus and 0.3 as Poisson coefficient. Select Mechanical ��Plasticity��picture to define the plastic behaviour of the material.

- Now create a new solid homogeneous sectionclicking on Sections in the model tree. Choose




and section properties

Start to define the material properties by clicking on Materials in the model tree.In the Edit material dialog box, type Steel as material name and select

�� Elastic as material behaviour in the material menu. 0e3 MPa as Young’s modulus and 0.3 as Poisson coefficient. Select

��Plastic and enter the values shown in the following picture to define the plastic behaviour of the material.

solid homogeneous section called Section_Steelclicking on Sections in the model tree. Choose Steel as material and click OK.



in the model tree. as material name and select

as material behaviour in the material menu. 0e3 MPa as Young’s modulus and 0.3 as Poisson coefficient. Select

and enter the values shown in the following

Section_Steel by as material and click OK.




- Assign the section to the beam. In the model tree, explode the explode the part called Beam and doublethe whole geometry of the beam and select the Section called part should turn from grey to green. assigned.

- Double click Assembly in the model tree, and ccheck the assembly and its




beam. In the model tree, explode the Partexplode the part called Beam and double-click on Section Assignmentthe whole geometry of the beam and select the Section called Sectionpart should turn from grey to green. Rigid tools do not need to have any material

Double click Assembly in the model tree, and click on the View Mesh Icon and and its already predefined mesh.



arts container, Assignment. Select

Section-Steel. The Rigid tools do not need to have any material

lick on the View Mesh Icon and




4. Define the analysis step - Double-click on Steps in the model tree and ccalled Load. Set Nlgeom parameter as on shown in the following picture.

- Move to the incrementation tabmaximum of 0.05.

- Create a second step called same parameters as the first step




Define the analysis steps

in the model tree and create a new Static, Gparameter as on and include automatic stabilisation

shown in the following picture.

incrementation tab and set an initial time increment of 0.01 and a

called Elastic Return using the same procedure and the as the first step.



General step automatic stabilisation as

et an initial time increment of 0.01 and a

using the same procedure and the




5. Define boundary and loading conditions Four boundary conditions are applied to this model. - Define a Symmetric displacement Double click on BCs in the model tree, call the boundary condition as X, select Initial as step and Symmetry/Antisymmetry/Encastre as type. Select face highlighted in the following

- Repeat the same to create a face of the beam shown below.




Define boundary and loading conditions

Four boundary conditions are applied to this model.

Symmetric displacement condition to the beam in the x direction. in the model tree, call the boundary condition as

select Initial as step and Symmetry/Antisymmetry/Encastre as type. Select following Figure as region and then X-SYMM

Repeat the same to create a BC-SYMM-Z boundary condition (Z-SYMM)

face of the beam shown below.



the x direction. in the model tree, call the boundary condition as BC-SYMM-

select Initial as step and Symmetry/Antisymmetry/Encastre as type. Select the SYMM as type.

SYMM) in the




- Create now a new Boundary condition called lower rigid tool. Select Initial as step and Symmetry/Antisymmetry/Encasttype. Select the reference point of the lower rigid body as region and ENCASTRE as type. All the nodes of this part will follow the movement of this node, thus the whole part will be fixed to its initial position.

- Lastly, create a Displacement/RotationSelect Load as step, Displacement/Rotationthe upper rigid body and enter the parameters as shown in the following picture.




Create now a new Boundary condition called BC-Encastre to encastre the lower rigid tool. Select Initial as step and Symmetry/Antisymmetry/Encast

the reference point of the lower rigid body as region and All the nodes of this part will follow the movement of this

node, thus the whole part will be fixed to its initial position.

Displacement/Rotation boundary condition called Displacement/Rotation as type, select the reference point of

enter the parameters as shown in the following picture.



to encastre the lower rigid tool. Select Initial as step and Symmetry/Antisymmetry/Encastre as

the reference point of the lower rigid body as region and then All the nodes of this part will follow the movement of this

boundary condition called BC-DISP. as type, select the reference point of

enter the parameters as shown in the following picture.




- Enter now the Boundary Conditions manager (in the model tree, right click on BCs and select Manager). Select the cell belonging to the Elastic return step column and the BC-DISP row. Click on field. This will return the rigid tool to its original position.

- Save the model. File �� Save

6. Define Interactions using General Contact approach

- Create new Interaction Property the model tree, call it IntPropfor Mechanical�� Normal BehaviourBehaviour, select Penalty as Friction formulation and enter 0.1 as friction coefficient.




Conditions manager (in the model tree, right click on Select the cell belonging to the Elastic return step

DISP row. Click on Edit and replace -35 with 0 This will return the rigid tool to its original position.

Save.

Define Interactions using General Contact approach

Create new Interaction Property by double-clicking Interaction PropertiestProp-1 and select Contact as Type. Select Hard contact

Normal Behaviour. Select Mechanical��Tangential , select Penalty as Friction formulation and enter 0.1 as friction



Conditions manager (in the model tree, right click on Select the cell belonging to the Elastic return step

in the U2

Define Interactions using General Contact approach

Interaction Properties in . Select Hard contact

Tangential , select Penalty as Friction formulation and enter 0.1 as friction




- Create now a new General Contactselect Initial as Step, call the new interaction as Contact as type. Keep All with selfthe parts of your system in contact with everything. Seinteraction property.

Interactions defined with general contact are very fast to be implementedtwo clicks also for complex models)definition by including/excludingindividual interaction properties

7. Create and Submit a J

- Double-click Jobs in the model tree and create a new Job called Select the Model-GC and click and open the Job-Manager. Highlight the job and click on Submit to start your analysisadvancement of the analysis. OManager.




General Contact interaction. Double click on Interactionsselect Initial as Step, call the new interaction as INT-GC and choose

All with self as contact domain to say that you want all the parts of your system in contact with everything. Select IntProp-1

Interactions defined with general contact are very fast to be implementedtwo clicks also for complex models). It is still possible, if needed, to improve the

including/excluding specific surface pairs or by assigning individual interaction properties to particular surface pairs.

and Submit a Job

in the model tree and create a new Job called Contact1GC and click Continue and then ok. Now, right-click on Jobs Manager. Highlight the job Contact1-GC previously created

start your analysis and on Monitor to monitor advancement of the analysis. Once it is terminated click on Results



Interactions, choose General

as contact domain to say that you want all 1 as global

Interactions defined with general contact are very fast to be implemented (only possible, if needed, to improve the

specific surface pairs or by assigning

Contact1-GC. click on Jobs

previously created to monitor the

in the Job-




8. View the Results - Visualize the complete model. Display options and enter the planes to mirror the model and exploit the symmetry of the system. Click




esults

Visualize the complete model. In the main menu bar, click on View Display options and enter the Mirror/Pattern tab. Tick the XY and YZ mirror planes to mirror the model and exploit the symmetry of the system. Click



In the main menu bar, click on View � Odb Tick the XY and YZ mirror

planes to mirror the model and exploit the symmetry of the system. Click OK.




- Visualize the displacementusing the tools highlighted in the following picture. Then return on the model tree bu clicking on the Model tab on top on the left.




displacement and the stress contour plots. Animateusing the tools highlighted in the following picture. Then return on the model tree bu clicking on the Model tab on top on the left.



Animate the analysis using the tools highlighted in the following picture. Then return on the model tree




9. Define Interactions using the Contact It is possible to define interactions in a different way. The approach is more time-consuming but it allows sometimes a wider range of interaction properties (rough friction), contactsurfaces, spheres, cylinders) and contact formulations (nodecontact is more limited. - Copy the Model-GC by rightselecting Copy Model. Rename the new mode - Explode the new model and collapse the Modelcontainer and delete Int-GC - Now define two new interactions between the beam and the two rigid tools. Double-click on Interactions, name the interaction Surface-to-Surface contactsurface, choose the colour (shell surface. Select Surface as slave region beam as shown in the following picture. - Once the Edit Interaction dialog box appears, choose property and click OK. - Repeat the same for the second




Define Interactions using the Contact-Pair approach

It is possible to define interactions in a different way. The Contact Pairsconsuming but it allows sometimes a wider range of

interaction properties (rough friction), contact domains (include analytical rigid surfaces, spheres, cylinders) and contact formulations (node-to-surface).

GC by right-clicking on Model-GC in the model tree and . Rename the new model as Model-CP.

Explode the new model and collapse the Model-GC. Go in the Interactions GC from Model-CP (Right-click and Delete)

Now define two new interactions between the beam and the two rigid tools. click on Interactions, name the interaction Int-Upper, select

contact as type. Select the upper rigid tool as master colour (brown or purple) that faces the beam

. Select Surface as slave region and select the upper face of the shown in the following picture.

Once the Edit Interaction dialog box appears, choose IntProp-1 as

second rigid tool and create the Int-Lower



Pair approach

Contact Pairs consuming but it allows sometimes a wider range of

domains (include analytical rigid surface). General

in the model tree and

GC. Go in the Interactions click and Delete).

Now define two new interactions between the beam and the two rigid tools. select Inital as step

as type. Select the upper rigid tool as master ) that faces the beam to define the

the upper face of the

as interaction

Lower contact pair.




- Double-click Jobs in the model tree and create a new Job called Select the Model-CP and click Continue and then ok. click on Jobs and open the Jobpreviously created and click on monitor the advancement of the analysis. Once it is terminated click on Resultsand check them as done in the previous section

10. Use the automatic Find contact pair tool As highlighted earlier, the contact paircase of large models and analyses. pair. Sometimes it is not even possible to know which surface will undergo contact. Abaqus offers a tool to overcome this issue to contact pairs and define new interactions. - Copy the Model-Cp as Modelinteractions previously created. - Click the Find Contact pairsthen click the Find Contact Pairs button. Notice that two contact pairs are found, the Intprop-1 has already been selecan be modified specifically. Click ok and notice that in the model tree, two new Surface-to-Surface interactions have been selected.




in the model tree and create a new Job called Contact1CP and click Continue and then ok. If not already open

click on Jobs and open the Job-Manager. Highlight the job Contact1previously created and click on Submit to start your analysis and on monitor the advancement of the analysis. Once it is terminated click on Results

done in the previous section. Results should be the same.

Use the automatic Find contact pair tool

As highlighted earlier, the contact pair approach could be very time-case of large models and analyses. A new interaction is define for each contact pair. Sometimes it is not even possible to know which surface will undergo

Abaqus offers a tool to overcome this issue to automatically find and define new interactions.

Model-CP-AUTOM as did before. Delete the two created.

Find Contact pairs icon as highlighted in the following picture and Find Contact Pairs button. Notice that two contact pairs are found, has already been selected as default. All the options in the cells

can be modified specifically. Click ok and notice that in the model tree, two new interactions have been selected.



Contact1-CP. ready open, right-

Contact1-CP to start your analysis and on Monitor to

monitor the advancement of the analysis. Once it is terminated click on Results Results should be the same.

-consuming in for each contact

pair. Sometimes it is not even possible to know which surface will undergo automatically find

before. Delete the two

picture and Find Contact Pairs button. Notice that two contact pairs are found,

cted as default. All the options in the cells can be modified specifically. Click ok and notice that in the model tree, two new




- Double-click Jobs in the model tree and create a new Job called AUTOM. Select the Model-opening the Job Manager, you can also rightand select Submit to start your analysis and of the analysis. Results can be accessed with this method as well.




in the model tree and create a new Job called Contact1-CP-AUTOM and click Continue and then ok.

opening the Job Manager, you can also right-click the Job Contact1to start your analysis and Monitor to monitor the advancement

Results can be accessed with this method as well.



Contact1-CP-AUTOM and click Continue and then ok. Without

-CP_AUTOM to monitor the advancement

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Three point bending: general contact and contact pairs