ptc creo simulate engine updates
TRANSCRIPT
PTC CREO SIMULATEENGINE UPDATES
Dr. Arun T. ChavanSenior Software Technical Consultant
March 28, 2017
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โข General improvements/fixes in simulate engineโ Engine fixes โ Engine improvements
โข Finite friction improvementsโ Local/full sliding messagesโ Slippage measuresโ Slippage indicatorsโ Interface forces
โข SAXSIM16 model discussionsโ Brake system with infinite friction โ Brake system with finite frictionโ Flywheel axisymmetric model
โข Creo 5.0 Simulate Engine contact projects
โข Conclusions
AGENDA
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ENGINE FIXES
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โข Performance with resistance elements.โข Temperature dependent materials.โข Integer overflow, engine crashes.
โข Measure calculations for several load cases.โข Fastener measure issue for dynamic shock analysis.โข Mixed shell, solid + contact model constraint issues
โข Advanced spring coupling stiffness matrixโข Contact model convergence โข Hyperplastic, elasto-plastic analysis convergence Etc.
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โข Snap-though analysis improvementsโ Algorithm improvementsโ sim_snap_tolerance_factor (sf)โ sf<1 requesting early start โ sf>1 requesting delayed startโ sf=1 default
โข NL Solver updatesโ Tuning improvement for finite friction โ Load displacement curve
โข sim_nl_ldcโ Accuracy improvements
โข Poorโข Mediumโข High
OVERALL ENGINE IMPROVEMENTS
Copyright 1987-2017 ยฉ PTC Inc. All rights reserved.
Courtesy NASA Langley Research Center
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โข NL Solver algorithm updatesโ Better control on penetration โ Energy convergence improvementโ Area/force convergence improvements
โข Contact force measures calculation updatesโ Contact interface load measure can be calculated from element stresses on user requestโ Contact interface tangential force measure improvement
โข Contact slippage indicator measure updatesโ Any slippageโ Average slippageโ Complete slippage
โข Contact slippage indicator fringe plot updatesโ Better many-to-few mappingโ Normalizationโ Sanity checks
โข Contact message improvementsโ In RPT file, for every interface, first occurrence of local/full sliding will be intimatedโ In PAS file, for every interface, current state of local/full sliding will be intimated
FINITE FRICTION IMPROVEMENTS
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โข Friction plays an important role in number of our daily activities and in most industrial processes. Friction not only aids in starting the motion of body but also in changing its direction and subsequently stopping it
โข FEM modeling of contacts with friction is of paramount importance for cases where one has to answer questions like:โ Will sliding occur? When will it occur? โ What kind of sliding occurs? Local sliding/Full sliding ? Or tipping?
โข We will study different scenarios to validate the simulation results
โข Sticking
โข Sliding, and
โข Tipping
FINITE FRICTION BASICS
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CASE STUDY 1: WHEN WILL SLIDING OCCUR?
ฮธ
y
z
Sr. No. Measure ฮธ = 12 deg ฮธ = 14 deg ฮธ = 16 deg
1 Interface1_average_slippage -1.393808e-03 3.421150e-03 1.416395e-02
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CASE STUDY 2: WILL TIPPING OR SLIDING OCCUR?
Interface1 is stuck, as:
โข Measure any slippage is +ve โข Measure average slippage โve
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โข Finite friction functionality does not workโ Interface force measure results for SPA are wrongโ Interface tangential force measure results are not accurateโ Interface slippage indicator results are not synchronized with RPT/PAS messagesโ Interface slippage measure results are inaccurate
โข Infinite friction SDA results are bad
โข Engine accepts very loose residual norm
โข Contact load measure in Creo 3.0 can not be used as mesh quality checking toolโ Creo 3.0 calculates it from spring forces โ Creo 2.0 calculates it from element stresses
โข Symmetry constraint and preload scaling issues
SAXSIM 2016: SUMMARY OF ISSUES REPORTED
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BRAKE SYSTEM: INFINITE FRICTION CASE
โข Two pads: โ pad_u and โ pad_o
โข Both C-frames โ stiff and โ fixed
โข Given displacement โ -0.01mm
โข Issues raisedโ Contact forces jump in SDA analysis โ Slippage indicator fringe plots
Copyright 1987-2017 ยฉ PTC Inc. All rights reserved.
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โข Infinite friction SDA analysis caseโ When run with increased contact number of iterations (say 500), the
Creo Simulate engine delivers interface force measure results that unreasonably jump after some time.
โ A fix is found and will be shipped in next possible build*
โข The work around is to run LDA analysis with an adequate number of output steps (e.g. 11). โ To ensure the sum of contact normal forces is 9600N, user can create a
user defined Interface force measure in WCS:X direction for pad_o and pad_u interfaces and add them.
โข The Screenshots of related measure plots are shared in next slides
BRAKE SYSTEM: INFINITE FRICTION CASE
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BRAKE SYSTEM: INFINITE FRICTION CASE
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SDA FIX LDA WORKAROUND SDA ISSUE
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BRAKE SYSTEM: INFINITE FRICTION CASE
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SDA FIX LDA WORKAROUND SDA ISSUE
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BRAKE SYSTEM: FINITE FRICTION RESULTS
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BRAKE SYSTEM: FINITE FRICTION RESULTS
1 2
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BRAKE SYSTEM: FINITE FRICTION RESULTS
pad_o_normal = ๐๐๐_๐_๐๐๐๐๐2 โ ๐๐๐_๐_๐ก๐๐๐_๐๐๐๐๐2
pad_o_normal = 5031.622 โ 1662.202 = 4749.14
pad_u_normal = 5139.382 โ 1697.802 = 4850.85
Total normal force = pad_o_normal + pad_u_normalTotal normal force = 9599.99 N
๐๐ =๐๐๐_๐_๐ก๐๐๐_๐๐๐๐๐
๐๐๐_๐_๐๐๐๐๐๐=
1662.20
4749.14=0.35
๐๐ข =๐๐๐_๐ข_๐ก๐๐๐_๐๐๐๐๐
๐๐๐_๐ข_๐๐๐๐๐๐=
1697.80
4850.85=0.35
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โข The contact force measures/slippage measures/slippage indicator calculationsโ are based on contact spring stiffnessโ are based on number of quadrature points (QPs) โ In general, number of QPs on a given element interface face/interface edge are
dense (.) as compared to number of h-nodes (.)on that face/edge
โข Contact indicator fringe plots are based on h-node gridโ The mapping from QPs to h-nodes is many-to-fewโ This is deliberately done for performance reasonsโ May result in loss of information for coarse h-node gridโ User can change h-nodes grid from Analysis dialog box
โข Contact indicator magnitudes are normalized in range [-1,+1]โ Red color is to indicate slidingโ Green color is to indicate sticking
IMPORTANT POINTS FOR FINITE FRICTION RESULTS
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FLYWHEEL: FINITE FRICTION
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FLYWHEEL: FINITE FRICTION
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FLYWHEEL: FINITE FRICTION
Force magnitude calculations:
Kegel_start_force =
๐พ๐๐๐๐_๐ ๐ก๐๐๐ก_๐๐๐๐๐_๐_๐๐๐๐2 + ๐พ๐๐๐๐_๐ ๐ก๐๐๐ก_๐๐๐๐๐_๐_๐๐๐๐2
Kegel_start_force = 2.85986E62 + 5.716860๐ธ52 = 2.91644E6 OR
Kegel_start_force = 2.802505E62 + 8.072097๐ธ52 = 2.91644E6
Axial force verification: Kegel_start_force_Y
Axial force =
Axial force = ๐ฒ๐๐๐๐_๐๐๐๐๐_๐๐๐๐_๐ฟ_๐๐๐๐๐๐๐(4.76364+11.31)
๐ถ๐๐ (11.31)
Axial force = 8.07498E5
Coefficient of friction Verification
๐๐พ๐๐๐๐ =๐พ๐๐๐๐_๐ ๐ก๐๐๐ก_๐๐๐๐๐_๐_๐๐๐๐
๐พ๐๐๐๐_๐ ๐ก๐๐๐ก_๐๐๐๐๐_๐_๐๐๐๐=
5.716860๐ธ5
2.859860๐ธ6=0.2
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โข Accuracy:โ Poor: MSE_CONTACT_FULL_LOOSER_CONVERGE: with this new ENV, engine will fully
activate looser tolerance acceptance algorithm. โ Medium: MSE_CONTACT_PARTIAL_LOOSER_CONVERGE: With this new ENV, engine will
partially suspend the looser tolerance acceptance algorithm โ it will make the convergence requirements a bit tighter than default, however it will not fully suspend the looser acceptance algorithm.
โ High: MSE_CONTACT_SUSPEND_LOOSER_CONVERGE: with this new ENV, engine will completely suspend the looser tolerance acceptance algorithm and will always seek for 1e-12 default convergence norm
โข Contact Interface load measureโ Creo 2.0, this is calculated from element stressโ Creo 3.0, this is calculated from spring stiffnessโ Creo 3.0, enable this with engine ENV
โข MSE_CONTACT_LOAD_FROM_STRESS
CREO 3.0 (M120) SIMULATE ENGINE ENVS SUPPORTED
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FEEDBACK ON SAXSIM2016 USER EXPERIENCE
PTC Actions:
โข As outlined in earlier slides, we have
already incorporated/fixed several issues
reported in the finite friction functionality related to high penetration and low
accuracy
โข We have also made available finite
friction verification and validation
examples to Simulate user community
โข We have plans to make available best
practice document to users that will primarily focus on addressing general
difficulties in contact analysis and
possible remedies*.
Copyright 1987-2017 ยฉ PTC Inc. All rights reserved.*Forward looking information is subjected to change without notice.
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โข New Contact Interface user defined measuresโ Max Penetrationโ Contact Spring stiffness
โข New Promotionsโ Config option sim_contact_penetration will be
promoted to interface dialog, allowing user to input different max penetration caps to each contact interface
โ Calculate detailed stresses at contact interfaces checkbox/flag will also be promoted to interface dialog, allowing user to selectively choose this flag based on requirements
โข New contact best practice Notes/help/paper will be made available to users
CREO 5.0 CONTACT PROJECTS*
*Forward looking information is subjected to change without notice. Copyright 1987-2017 ยฉ PTC Inc. All rights reserved.
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โข Finite friction issues are fixed and result validation/verification study cases are
published in NAFEMS international conference last year
โข SAXSIM2016 inputs/findings were recorded and appropriate action has been
taken to resolve customer concerns
โข Engine Enhancements in upcoming Creo 5.0 Simulate release*
โ Roadmap presented this morning by Jose Coronado, PM, Simulate.
โ Contact related projects are being implemented
CONCLUSIONS
Copyright 1987-2017 ยฉ PTC Inc. All rights reserved.*Forward looking information is subjected to change without notice.