Other BEASY Tools: Stiffened Panels

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Other BEASY Tools Stiffened Panels
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Stiffened Panel Models

• Panels Stiffened by Beams
• Rivet Attachments
• Panels Stiffened by doublers
• Rivet Attachments
• Panels with doublers and Beams

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Modelling Doublers

• Doublers are modelled by a 2D boundary element
  zone shaped identically to the doubler.
• Boundary elements are required on both external
  edge and cut outs

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Multiple Beams

• Multiple Beams
• Additional Connectors

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Basic Doubler Example
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Stresses 9 Connectors
Base Panel
Doubler
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Doubler with Multiple Holes
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Panel Stiffened By Ribs
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Simple Panel With Beams
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Effect of Stiffeners
No Beam Deformation Scale Factor 2
With Beam Deformation Scale Factor 2
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Fatigue Growth Comparison
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Growth In Stiffened Panel Structures

• Structures can consist of
• Multiple panels
• Doublers
• Beams ribs etc
• Fasteners

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Design Wizard Simplifies Model Development
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Other BEASY Tools BEASY Contact
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Contact Algorithm

• The BEASY contact algorithm is a constraint based
  methodology which results in
• Exact representation of surface conditions
• No penalty or artificial spring coefficients
• High accuracy
• Accurate prediction of frictional effects
• Accurate representation of surface stresses and
  contact geometry
• The algorithm is automatic and self adjusting
• Two types of contact algorithm are available

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Types of Contact Problem

• Conforming contact
• The two surfaces are of similar shape
• A small difference in shape can be modelled using
  for example an initial gap or interference fit
• A node to node contact algorithm can be used
  providing the displacement are not very large

Pin and Lug
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Types of Contact Problem

• Non Conforming Contact (Surface to
  Surface)
• The two surfaces can be radically different in
  shape
• Node to node contact cannot normally be used
• Large displacements are possible

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Types of Contact Problem

• BEASY can solve both
• Conforming Contact (Node to Node)
• Non Conforming Contact (Surface to Surface)

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Spline Coupling Analysis

• Contact analysis including
• Friction
• Slip and Contact Pressure

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Spline Shaft Joint Model Under Torque
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BEASY-Non-conforming Contact
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BEASY-Non-conforming Contact

• Resultant displacement on deformed shape

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BEASY-Non-conforming Contact

• Principal stress

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Summary

• The BEM surface only technology provides the key
  to simulation based design
• Substantial savings can be achieved in model
  building time
• Flexibility to consider alternative design
  options quickly.
• Product integrity
• Realistic models

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Other BEASY Tools BEASY Contact with Wear
Calculations
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Wear Prediction

• Wear occurs when
• Components are in contact
• The loads are varying causing slip
• Wear can be due to
• Fretting
• Reciprocating wear
• Wear changes the geometry which results in
  changes to
• Contact Pressure
• Stress distribution
• BEASY provides the information necessary to
  predict wear

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Auxiliary Rail Configuration
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Predicting Wear

• The operators of a wagon maintenance depot raised
  the question of wear of an auxiliary rail that
  was used in an underfloor lifting system.
• In order to try to answer this question,
  information about the contact stresses and
  contact area between the flange and the auxiliary
  rail would need to be obtained.
• The contact model in BEASY was used to provide
  the detailed contact stresses and micro slip
  necessary for wear prediction.

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Rail and Wheel Contact Model
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Von Mises Stresses on Wheel and Rail Surfaces.
Deformation
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Wear Prediction

• Wear was calculated for the analysis using
  Archards Law
• This is a simple wear equation which states that
  wear is a function of-
• Contact load
• Sliding distance (slip)
• Where
• d is the sliding distance,
• k is a load-independent constant that describes
  the wear rate,
• W is the contact load
• Y is the material yield stress.

Wear Rate (d.k.W)/Y
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Wear Prediction
Variation of Archards constant k with wear and
lubrication conditions. Source Rabinowicz(1976)
Wear Rate (d.k.W)/Y
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Wear Prediction

• The distribution of wear on the contact surface
  can be predicted.
• A single value of the wear rate can also be
  calculated by averaging the wear results over all
  the contact nodes.
• The average wear rate that was calculated was
  7.2310-6mm per wheel traversal.
• For a design life of 10 years, with 24 wheel
  traversals per day, the total wear for the
  auxiliary rail is estimated to be 0.63mm.

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Other BEASY Tools Contact solutions for a
fretting test example
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Conceptual Model of Fretting Test
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Fretting Tests Mesh
Exploded view
0.01
0.075
0.125
Y
X
0.075
0.1
Cylindrical surface
Flat surface
0.14
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Fretting Tests Loads
Frictionless rollers
To simulate the fretting test the horizontal load
Q is reversed cyclically
x displacement 0
?bulk
y displacement 0
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Fretting Tests Results display

• Graph plots will be shown of variation of results
  along the center-line of the contact region on
  the surface of the flat block
•  

Graph plots will show variation of results along
this line
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Horizontal Direct Stress (?xx)  
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Vertical Direct Stress (?yy)
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Shear Stress (?xy)
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Fretting Tests

•   Shear component of contact stress on surface of
  flat block

Bands running in the z direction confirm the
model is behaving in a 2D (plane) way
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Fretting Tests Test 1 (P,Q,sr0)

•   Direct stress (?zz)

Non-zero zz component of direct stress confirms
the model is behaving in a 2D plane strain way
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Fretting Tests Test 1 (P,Q,sr0)

Lower peak at right is caused by boundary
conditions. See later investigation into effect
of restraints
Sharp peak has been cut-off by location of
data-points
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Fretting Tests Test 1 (P,Q,sr0)

Result approaches some positive value, reflecting
overall tension at this end of the block
Result approaches zero, reflecting stress-free
condition at this end of the block
Contact region extends here
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Fretting Tests Tests 2-gt6

sr2
sr4
sr6
sr8
sr1
sr0
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Fretting Tests Tests 7 (P,sr2), ie Q0

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Fretting Tests Cyclic load

• The effect of cyclic loading can be investigated,
  simply by defining a series of load cases to
  represent the different loads
• Compressive load
• Side load
• Tension in specimen
• The sequence in which the loads are applied is
  then defined
• The results of such a study are shown on the next
  few slides

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Fretting Tests Cyclic load

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Fretting Tests Cyclic load

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Summary

• The BEM surface only technology provides the key
  to simulation based design
• Substantial savings can be achieved in model
  building time
• Flexibility to consider alternative design
  options quickly.
• Allows wear and fretting to be computed
• Product integrity
• Realistic models

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The BEASY Fracture Wizard
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Example Model
BEASY model with simple surface mesh
No need to model the crack in the BEASY mesh
Generate a 3D model of a plate with a through
edge crack
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Crack Wizard worked example
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Specify the crack initiation point in the
fracture wizard
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Select A Crack From The Wizard Crack Library
The crack library contains a selection of corner
cracks, edge crack and through cracks
Additional cracks can be generated and added to
the library as required
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Select the growth model using the wizard
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Select the material properties
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Choose the loading
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A BEASY Model with the crack is automatically
generated
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The crack growth is automated
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Predicted Crack Growth
Crack has grown to here
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Deformation and stress intensity data