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Training Manual
7. Introduction to Contact
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Training Manual7. Introduction to contact
What is contact?
When two separate surfaces touch each
other such that they become mutuallytangent, they are said to be in contact.
In the common physical sense, surfacesthat are in contact have thesecharacteristics:
They do not interpenetrate. They can transmit compressive normal
forces and tangential friction forces. They often do not transmit tensile normal
forces. They are therefore free to separate and
move away from each other.
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Training Manual Introduction to contact
In this chapter, we will present an introduction to nonlinearcontact analysis via the following topics:
A. Basic concepts
B. Using the contact wizard
C. Obtaining the solution
D. Postprocessing
E. Workshop
F. Assembly contact
The purpose is to introduce you to contact analysisprocedures for simple (easily converged) models. Other,more advanced aspects of contact analysis that are used tohandle more difficult models are discussed in the Advanced Contact and Bolt Pretension training manual.
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Training Manual
Introduction to contact
A. Basic Concepts
Contact is a changing-status nonlinearity. That is, thestiffness of the system depends on the contact status:
Status = Open Status = Closedand Sticking
Status = Closedand Sliding
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Training Manual
Introduction to contact
... Basic Concepts
Contact is a strong nonlinearity, because both the normaland tangential stiffness at contact surfaces changesignificantly with changing contact status.
Large, sudden changes in stiffness often cause severeconvergence difficulties.
u
F
Opencontact
Closedcontact
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Training Manual
Introduction to contact
... Basic Concepts
Other factors that make contact analysis complicatedinclude:
The region of contact is typically unknown at the start of the
analysis. Most contact problems include friction.
Friction is a path-dependent (energy-dissipating)phenomenon that requires an accurate load history, withsmall time steps.
Frictional response can be chaotic, making solutionconvergence difficult.
Parts might be unconstrained except for contact with otherparts.
Prior to establishment of contact, such parts are initiallyunconstrained free bodies, with zero overall stiffness.
In a static analysis, unconstrained free bodies aremathematically unstable. The solution blows up.
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Training Manual
Introduction to contact
... Basic Concepts
Fortunately, current ANSYS contact technology enables youto analyze a broad class of contact models fairly easily.
Many models can be solved successfully with very little userintervention.
For those models that exhibit more difficult convergencebehavior, a rich library of contact element options are
available to help you overcome such difficulties. These more advanced features are discussed in the Advanced
Contact and Bolt Pretension training manual.
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Training Manual
Introduction to contact
... Basic Concepts
Contact classification
Contact problems fall into two general classes:rigid-to-flexible and flexible-to-flexible.
Rigid-to-flexible One or more contacting surfaces are treated as rigid. (One
surface has a significantly higher stiffness than the other.)Many metal forming problems fall into this category.
Stresses within the rigid body are not calculated.
Flexible-to-flexible Both or all contacting bodies are deformable. (All surfaces
have similar stiffnesses.) A bolted flange connection wouldbe an example of flexible-to-flexible contact.
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Training Manual
Introduction to contact
... Basic Concepts
Rigid-to-flexible contact
Rigid Surface
DeformableBody
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Training Manual
Introduction to contact
... Basic Concepts
Flexible-to-flexible contact
Splined shaft interference
fit, both parts are flexible.
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Training Manual
Introduction to contact
... Basic Concepts
Contact compatibility
Physical contacting bodies do not interpenetrate. Therefore,the program must establish a relationship between the twosurfaces to prevent them from passing through each other inthe finite-element analysis.
When the program prevents interpenetration, we say that it
enforces contact compatibility.F
TargetContact
Penetration occurs when contact compatibility is not
enforced. F
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Training Manual
Introduction to contact
... Basic Concepts
Contact compatibility penalty method
The penalty method of enforcing contact compatibility uses acontact spring to establish a relationship between the twosurfaces.
The spring stiffness is called the penalty parameter or, morecommonly, the contact stiffness .
The spring is inactive when the surfaces are apart (open status),and becomes active when the surfaces begin to interpenetrate(closed).
The spring will deflect anamount , such that equilibriumis satisfied:
F = k where k is the contact stiffness.
F
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Training Manual
Introduction to contact
... Basic Concepts
contact compatibility penalty method
Some finite amount of penetration, , is requiredmathematically to generate a contact force at the interface.
This contact force is needed for equilibrium. Thus, must be greater than zero for equilibrium.
However, physical contacting bodies do not interpenetrate. Therefore, for best accuracy, the goal is to minimize the
amount of penetration that occurs at the contact interface.
Minimum penetration gives maximum accuracy. This implies that, ideally, the contact stiffness should have a
very great value. However, too high of a value can lead to convergence
difficulties.
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Training Manual
Introduction to contact
... Basic Concepts
If the contact stiffness is too great, a slight penetration willgenerate an excessive contact force, potentially throwing thecontacting surfaces apart in the next iteration.
Using too great a contact stiffness usually leads to oscillatingconvergence, and often to outright divergence.
Iteration n Iteration n+1
F
F
F contactF
Iteration n+2
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Training Manual
Introduction to contact
... Basic Concepts
Contact compatibility Lagrange multiplier method
An alternative method, the Lagrange Multiplier method, adds
an extra degree of freedom (contact pressure), to satisfy theimpenetrability condition.
F
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Training Manual
Introduction to contact
... Basic Concepts
Contact compatibility augmented Lagrangian method The most modern ANSYS contact elements can combine both
the penalty method and the Lagrange multiplier to enforcecontact compatibility. This is called the augmented Lagrangian method.
In the first series of iterations, contact compatibility isdetermined based on the penalty stiffness. Once equilibriumis achieved, the penetration tolerance is checked. At thispoint, if necessary, the contact pressure is augmented andthe iterations continue.
F
PenetrationTolerance
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Training Manual
Introduction to contact
... Basic Concepts
contact compatibility augmented Lagrangian method
Penetration
correctiondue to equilibrium.
Oscillation occursduring correctionstage.
Augmentingcontact stresses toreduce
penetration.
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Training Manual
Introduction to contact
... Basic Concepts
Surface-to-surface elements
The most modern contact elements available in ANSYS arethe surface-to-surface elements.
Targe169 and 170 Rigid or deformable target surfaces
Conta171 to 174 Deformable contact surfaces
These elements are well suited for surface-to-surface contactapplications such as interference fit assembly contact, entry
contact, forging, and deep drawing.
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Training Manual
Introduction to contact
... Basic Concepts
surface-to-surface elements
These contact elements use the concept of a contact pair,which is composed of a target surface and a contact surface.
The surface-to-surface contact elements overlie the underlyingfinite element model like a skin.
Separate element types define the target and contact surfaces. The contact pair is identified through a shared real constant set.
Contact elements (REAL = N )
on the contact surface
Target elements (REAL = N )
on the target surface
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Training Manual
Introduction to contact
... Basic Concepts
surface-to-surface elements
ANSYS supports both rigid-to-flexible and flexible-to-flexible surface-to-surface contact models.
Flexible-to-flexible models have a deformable target surface ,
which is created whenever target elements overliedeformable elements.
Rigid-to-flexible models have a rigid target surface , whichdoes not overlie any deformable elements.
Rigid target element
Contact elements
Underlyingmesh
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Training Manual
Introduction to contact
... Basic Concepts
surface-to-surface elements
The surface-to-surface contact elements use the augmented Lagrangian to enforce contact compatibility (default).
Augmented Lagrangian uses both a contact stiffness and apenetration tolerance.
For simple contact models, you will normally need tospecify just three characteristics of the contact pair:
A value for the contact stiffness A value for the penetration tolerance.
You will also need to determine which surface in the pair shouldbe the target, and which should be the contact.
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Training Manual
Introduction to contact
... Basic Concepts
Contact stiffness
The contact stiffness is the most important parameteraffecting both accuracy and convergence behavior.
Recall that greater stiffness gives better accuracy, but moredifficult convergence.
You must carefully determine an appropriate value forcontact stiffness.
The best value is often problem-dependent. Program-supplied default value will often not be appropriate.
Some experimentation may be required to determine anappropriate value that generates a converged solution with anacceptable level of accuracy.
d
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Training Manual
Introduction to contact
... Basic Concepts
contact stiffness For the surface-to-surface elements, you specify the contact
stiffness as a factor (FKN). That is, the program determinesthe contact stiffness by multiplying the stiffness of theunderlying element times a factor that you specify.
kcontact = FKN x f(k underlying )
For the surface-to-surface elements, the contact stiffness hasunits of stiffness per unit area, or (F/L)/(L 2). A good value for contact stiffness is often obtained by
making the contact stiffness equal to the stiffness of the
underlying elements. As a starting estimate, try:
FKN = 1.0 for bulky solids in contact.
FKN = 0.1 for more flexible (bending-dominated) parts.
I d i
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Training Manual
Introduction to contact
... Basic Concepts
contact stiffness
Sometimes, different regions of a model may need to havedifferent contact stiffnesses.
Bulky contact; try FKN = 1.0
Flexible contact; try FKN = 0.1
I t d ti t t t
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Training Manual
Introduction to contact
... Basic Concepts
contact stiffness Determining a good stiffness value may require some
experimentation. The following procedure may be used as a
guideline: Use a low value of FKN to start. Run the analysis to a fraction of the final load.
Check the penetration and number of equilibrium iterations usedin each substep. If convergence is being driven by the penetration tolerance,
FKN may be underestimated (or the penetration tolerancemay simply be too tight).
If no force convergence, or if many iterations are required toobtain force convergence, FKN may be overestimated.
Adjust FKN and run the full analysis.
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Training Manual
Introduction to contact
... Basic Concepts
contact stiffness
Because results can be sensitive to the value used for FKN,you should always verify the validity of your results.
If you have any doubts about the validity, perform a sensitivitystudy.
Vary the contact stiffness and re-run.
Monitor some item of significance to your analysis, suchas:
Contact pressure. Maximum stress.
Look for a value of FKN beyond which results stabilize to afairly consistent value.
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Training Manual
Introduction to contact
... Basic Concepts
contact stiffness
As an example, FKN was varied for an interference-fitanalysis of a collar on a shaft. Maximum equivalent vonMises stress was monitored.
In this particular case, a value of FKN = 1.0 proved to giveadequate accuracy.
FKN Max. SEQV
0.001 4,000
0.01 20,0000.1 65,0001 91,000
10 92,900100 93,000
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Training Manual
Introduction to contact
A. Contact stiffness Workshop
Please refer to your Workshop Supplement for instructions on:
W14. Introduction to Contact - Contact Stiffness Study (FKN)
Introduction to contact
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Training Manual
Introduction to contact
... Basic Concepts
Penetration tolerance
The penetration tolerance also affects convergence andaccuracy, although to a lesser extent than the contactstiffness.
As the penetration tolerance is tightened, the accuracy mayimprove, but at the expense of more difficult convergence.
As with the stiffness, you specify thepenetration tolerance by means of a factor (FTOLN).
The program determines the penetrationtolerance by multiplying the depth of theunderlying element (h) times a factor that youspecify.
Tolerance = FTOLN x h
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Training Manual
Introduction to contact
... Basic Concepts
penetration tolerance
Dont use a soft FKN and a tight FTOLN.
Best convergence behavior is usually obtained if the contactstiffness does most of the work of enforcing compatibility.
Use a reasonably stiff value for FKN.
Fine-tune the penetration with a reasonable value ofFTOLN.
Too small a value for FTOLN will lead to convergencedifficulty. Never use too small of a tolerance! Increasing the
penalty stiffness (FKN) will reduce the penetration. Although increasing FKN by 100 times will usually reduce the
penetration accordingly, other items of significance, such asthe contact pressure, might change by as little 5%.
Introduction to contact
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Training Manual
Introduction to contact
A. Penetration tolerance Workshop
Please refer to your Workshop Supplement for instructions on:
W15. Introduction to Contact - Penetration Tolerance Study(FTOLN)
Introduction to contact
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Training Manual... Basic Concepts
Designating contact and target surfaces The program defines the contact surface by a set of discrete
contact points (the element Gauss points). The program defines the target surface as a continuous
surface. The two surfaces can interpenetrate between the Gauss
points, without contact being recognized. This causesinaccuracies.
Target Surface
Contact Surface
The target can penetrate the contact surface in between the Gauss points.
Introduction to contact
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Training Manual... Basic Concepts
designating contact and target surfaces
You can reduce the amount of unrecognized interpenetrationby careful designation of the target and contact surfaces.
However, for rigid-to-flexible contact, the choice of target andcontact is unchangeable. The rigid surface must always bethe target.
Steel shaft (rigid)must be the targetsurface
Rubber boot (flexible)must be the contactsurface
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Training Manual
designating contact and target surfaces
For flexible-to-flexible contact, best accuracy is achieved bymaximizing the number of contact points. Follow theseguidelines when designating flexible-to-flexible contact andtarget surfaces:
If one surface has a coarse mesh and the other a fine mesh, thesurface with the coarse mesh should be the target surface.
Consider what would happen if the designations werereversed:
... Basic Concepts
xxxxIf the finer mesh were the
target, it would droopacross the Gauss points,and penetrate as shown.
Introduction to contact
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Training Manual... Basic Concepts
designating contact and target surfaces
Other guidelines for designating contact and target surfaces: If a convex surface comes into contact with a flat or concave
surface, the flat or concave surface should be the target surface.
If one surface is stiffer than the other, the stiffer surface shouldbe the target surface.
If one surface is higher order and the other is lower order, thelower order surface should be the target surface.
If one surface is larger than the other, the larger surface shouldbe the target surface.
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Training Manual... Basic Concepts
designating contact and target surfaces When all contact elements are on one surface and all target
elements are on another surface, the model is said to have
asymmetric contact. Asymmetric contact is generally the most efficient way to model
surface-to-surface contact. However, under some circumstances asymmetric contact will
not perform satisfactorily. No clear distinction exists between target and contact
surfaces.
Both target and contact surface have coarse meshes.
Sometimes the target-contactdistinction is not clear
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Training Manual... Basic Concepts
designating contact and target surfaces
An alternative approach is to create a double set of contactpairs. This is known as symmetric contact.
After creating one contact pair, simply create a secondcontact pair having a reversed target-contact designation, forthe same surfaces.
Contact
Target
Target
Contact
Step 1 - Create 1 st
Contact Pair
Step 2 - Create 2 nd
(Symmetric) Contact Pair
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Training Manual... Basic Concepts
designating contact and target surfaces
Although some models may require symmetric contact foraccuracy, be aware that it is less efficient than asymmetriccontact.
Therefore, dont use symmetric contact unless it is required.
Note also, that when using symmetric contact,postprocessing is more difficult.
The contact pressure is the average value from both sets ofcontact elements.
This average value is not automatically available as a standardresults item. You will need to calculate it using APDL orETABLE.
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Training ManualA. Contact & target Workshop
Please refer to your Workshop Supplement for instructions on:
W16. Introduction to Contact - Contact & Target Designation
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Training Manual... Basic Concepts
Rigid target surfaces pilot node By default, the program will automatically constrain a rigid
target surface. That is, it will automatically ground the target
with zero-value displacements and rotations. To model more complicated behavior of the rigid target, you
can create a special one-node target element, called a pilot node.
This element is associated with the target surface by means ofhaving the same REAL attribute.
The pilot node acts as a handle for the entire rigid surface.
You can specify nonzero displacements, rotations, forces,and/or moments at the pilot node to model rigid-body motion ofthe target surface.
Note that if a pilot node exists, the program will not auto-
constrain the rigid surface.
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Training Manual... Basic Concepts
pilot node
The pilot node can be specifiedat any location. This allows forgeneral rotations of the rigidtarget surface.
Only the pilot node can connect
to other elements. Forexample, to account for themass of a rigid body, define amass element (MASS21) at the
pilot node. Each target surface can have
only one pilot node.
Rigid surface rotated
Pilot node
(at centerof rotation)
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i h i d
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Training ManualB. Using the contact wizard
Surface-to-surface contact elements can be created usingstandard element-generation procedures: establish elementTYPE, REAL, and MAT data, set element attributes, designate
target and contact surfaces, and then either mesh or useESURF operations.
This procedure forces you to carry a fairly heavy mentaloverhead as you create your contact pairs.
Fortunately, there is a better way ...
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U i h i d
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Training Manual... Using the contact wizard
The contact wizard provides a simple way to construct acontact pair for most contact problems. The contact wizardwill guide you through the process of creating a contact pair.
Preprocessor > Create > Contact Pair > Contact Wizard
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Training Manual... Using the contact wizard
Benefits of the Contact Wizard: Automatically defines element types and real constant sets Quickly accesses the contact options and parameters Contact pair viewing tools Quickly displays and reverses contact normals
The Contact Wizard is not available until you have meshed some portion of your model.
Before launching the wizard to create a flexible-to-flexible model,mesh all parts of the model that will be used as contact surfaces.
To create a rigid-to-flexible model, mesh only the parts of themodel that will be used as flexible contact surfaces.
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U i g th t t i d
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Training Manual... Using the contact wizard
Lets see how we could add a contact pair to the connectormodel from the Chapter 6 workshops.
First, designate rigid or flexible target type (if a choice isapplicable), and pick the target surface. You can pick nodes, nodecomponents, lines, or areas, depending on what entities are presentin the model.
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Training Manual... Using the contact wizard
Next, pick the contact surface. Again, you can pick nodes, nodecomponents, lines, or areas, depending on what entities are presentin the model.
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Using the contact wizard
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Training Manual... Using the contact wizard
If you need to include friction effects, specify the coefficient of friction.(More on friction on the next slide.)
Click on Optional settings tospecify the contact stiffness andpenetration tolerance. (Otheroptions will be discussed in theAdvanced Contact and Bolt
Pretension training course.)
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Training Manual... Using the contact wizard
A note about friction The surface-to-surface elements provide a basic Coulomb
friction model that defines the equivalent friction stress atwhich sliding occurs: = x p
is the coefficient of friction, defined as a material property, asshown in the contact wizard on the previous slide.
If equals zero (default), no shear stress will be transmitted. p is the contact pressure.
When the shear stress between the two surfaces exceeds x p, the two surfaces will slide relative to each other.
More advanced friction options are also available. They arediscussed in the Advanced Contact and Bolt Pretension training manual.
T i i M l
Introduction to contact
Using the contact wizard
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Training Manual... Using the contact wizard
Last, click on Create to create the contact and target elementsthat comprise this contact pair.
The REAL constant
set used for thispair is identified.
The elements in the pair areautomatically plotted, with their ESYSsymbols ON to indicate outwardnormal directions. If any normals arepointing in the wrong direction, youcan flip them now.
T i i g M l
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Training Manual
At any time after a contact pair is created, you can also usethe wizard to view and list the elements.
... Using the contact wizard
Training Manual
Introduction to contact
Using the contact wizard
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Training Manual... Using the contact wizard
You can also use the wizard to delete a contact pair.
Training Manual
Introduction to contact
Using the contact wizard
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Training Manual... Using the contact wizard
Pilot node The contact wizard does not enable you to create a pilot node
for a rigid target surface. To create a pilot node, you will have
to use meshing or direct generation: First, set the element attributes (MAT, REAL, TYPE) for the target
elements. Remember to use the same REAL set as for the rest of the
contact pair. Then mesh a keypoint that is located at the desired position for
the pilot node. Recall that the pilot node can be at any location it is not
required to be physically attached to the other targetelements.
Alternatively, for direct generation, set an additional attribute forthe target-element shape (TSHAP, PILO ) and then create the
element at the desired node.
Training Manual
Introduction to contact
C Obtaining the solution
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Training ManualC. Obtaining the solution
Automatic solution control, along with the default optionsettings for surface-to-surface elements, generally leads tofairly robust solutions for a broad class of contact analyses.
If convergence difficulties are encountered, they generallyarise due to one or more of three causes: Too great a value for contact stiffness. Too tight a value for penetration tolerance. Too large a value for minimum time step size.
To improve convergence, try these modifications to yourmodel, in the following order of implementation:
Use a smaller FKN. Use a larger FTOLN. Use a smaller minimum time step size (or larger maximum
number of substeps).
Training Manual
Introduction to contact
... Obtaining the solution
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Training Manual... Obtaining the solution
If your model still wont converge with modified FKN, FTOLN,and time step size, then the advanced contact options willprobably be needed.
These are discussed in the Advanced Contact and Bolt Pretension training manual.
If your model includes friction, small time step sizes arerequired for accuracy, because friction is a path-dependentphenomenon.
Unlike plasticity, there is no cutback control that will triggerbisection if a friction time step is too large.
Note that in a contact solution, all equilibrium iterations arecarried out before bisection for the first substep, to helpestablish initial contact conditions.
Training Manual
Introduction to contact
D. Postprocessing
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gD. Postprocessing
Results from contact models will contain many additionalitems related to contact. Some of the more commonly useditems include:
STAT Contact StatusPENE PenetrationGAP GapPRES Contact PressureSFRI Friction Stress
These items are associated with the contact element (not thetarget element), and can be readily accessed in the GUI.
Using the General Postprocessor, you can display them in Nodal(averaged) or Element (unaveraged) contour plots.
Animated plots are especially helpful for contact analyses. Using the Time-History Postprocessor, you can plot them as
time-history variables.
Training Manual
Introduction to contact
... Postprocessing
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p g
The contact status is an integer number that designates thecurrent status of the contact element:
STAT = 0: Open and not near contact.
STAT = 1: Open, but near contact. STAT = 2: Closed and sliding. STAT = 3: Closed and sticking.
Training Manual
Introduction to contact
... Postprocessing
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p g
Note that a Nodal (averaged) contour plot of status will exhibit non-integer contour values, due to the averaging. Element (unaveraged)contour plots are usually more appropriate for contour plots ofelement status.
Similarly, anomalous Nodal contour plots can occur for othercontact results items. If a Nodal (averaged) contour plot doesntseem to make sense, try an Element (unaveraged) plot instead.
Contact Region Status >1 innodal
contour plot
Status = 1 inelement
contour plot
Training Manual
Introduction to contact
... Postprocessing
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p g
The penetration or gap distance represents the actual amountof penetration (for STAT = 2 or 3) or open gap (for STAT = 1),in consistent units of length.
In listings, penetration distance is positive, and gap distance isnegative. Because contour plots display either penetration or gap (not
both simultaneously), the contours always display as positive
values for both items. The contact pressure (PRES) and friction stress values (SFRI)
represent the current values for the contact element, copiedfrom the Gauss points to the nodes.
Training Manual
Introduction to contact
E. Workshop
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p
Please refer to your Workshop Supplement for instructions on:
W17. Introduction to Contact - Snap-fit
Training Manual
Introduction to contact
F. Assembly contact
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Many analysts now import solid models from CAD packages,and then mesh and analyze the imported models in ANSYS.
For most CAD programs, a single volume, however complex,
represents a single part. Multiple-volume models will haveseveral parts associated together in an assembly.
Part B
Part A
Training Manual
Introduction to contact
... Assembly contact
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The boundaries between parts within an assembly usuallyrepresent mathematical discontinuities within the CAD model.
When meshed in ANSYS, there will be a discontinuity in the
mesh at these part boundaries. Nodes on one side of theboundary will not talk with nodes on the other side of theboundary.
Surface-to-surface contact elements can be used to connect
the mesh across part boundaries, using a concept known asassembly contact.
Glue parts A & B
together usingassembly contact
Training Manual
Introduction to contact
... Assembly contact
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Although assembly contact uses advanced contact featuresto glue parts together, the procedure is straightforward andvery consistent for different models.
In fact, ANSYS Inc.s designer-level product, DesignSpace,includes automated assembly-contact procedures. It has beenused successfully by designers who have no concept ofnonlinear analysis procedures.
Because assembly contact is widely applicable, and isusually simple (i.e., having robust convergence behavior),we will present the procedure here, with little explanation ofthe advanced features being used.
Training Manual
Introduction to contact
... Assembly contact
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The CAD assembly must have these characteristics: The parts must touch each other along a boundary. The boundary surfaces need not match perfectly; some
mathematical noise in the geometry is tolerable. The two adjacent parts must be meshed before an assembly
contact pair can be generated.
Training Manual
Introduction to contact
... Assembly contact
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As a tool for gluing interfacing boundaries together,assembly contact is more generally applicable thanNUMMRG, EINTF, CPINTF, CEINTF, and other such tools thathave been used in the past.
It is valid in large-displacement analyses (unlike coupling andconstraint equations).
It can connect mismatched meshes (unlike NUMMRG and
EINTF). Assembly contact takes advantage of the bonded contact
feature of the surface-to-surface contact elements to gluedisconnected parts together.
To model a stronger bond, a very stiff value of FKN is oftenused.
It is not unusual to use FKN = 10.
Training Manual
Introduction to contact
... Assembly contact
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The key to assembly contact is the creation of an initiallyperfect contacting surface having no initial forces actingacross the contact interface.
This is achieved by using the Exclude everything initial-penetration option, along with the Bonded (always) contactsurface behavior:
Training Manual
Introduction to contact
... Assembly contact
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If the only nonlinearity in your model is assembly contact, youcan sometimes turn nonlinear iterations off in your analysis.
Solution > Unabridged Menu > -Load Step Opts- Solution Ctrl
Solution >Unabridged Menu >-Load Step Opts- Nonlinear>Equilibrium Iter
However, realize that turning off nonlinear iterations couldproduce a model that is not in perfect equilibrium.
Turn automaticsolution controlOFF
Specify ONEequilibriumiteration
Training Manual
Introduction to contact
... Assembly contact
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A model that has parts glued together with assembly contactcan be used in many types of analyses, including:
Nonlinear static.
Nonlinear transient dynamic. Linear modal. Linear eigenvalue buckling.
The initial status of the contact elements is frozen in alinear analysis (such as modal or eigenvalue bucklinganalysis).
Training Manual
Introduction to contact
F. Assembly contact Workshop
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Please refer to your Workshop Supplement for instructions on:
W18. Introduction to Contact - Assembly Contact