Nafems Gothenburg 2005 Veltri
Transcript of Nafems Gothenburg 2005 Veltri
NAFEMS SEMINAR
“Component & System Analysis Using Numerical Simula tion Techniques- FEA, CFD, MBS”| 23 – 24 November, 2005 | Gothenburg, Sweden
Virtual Product Development
Automated Durability Design of Crankshafts Based on MSC.Adams/Engine
Ing. Marco Veltri, Technical Consultant MSC.Software Ltd
NAFEMS Seminar “Component and System Analysis Using Numerical Simulation Techniques- FEA, CFD, MBS”
23 – 24 November, 2005 | Gothenburg, Sweden
Overview
• VPD, Virtual Product Development, applied to Crankshaft Design
• FEA – MBS and Fatigue tools• Problem size and missing link: the need for
automation
• Automated Process Flow• Assisted FEM, MBS and Fatigue simulation
analysis• The quest for automation: Managing Data vs.
producing data
Windows Explorer.lnk
NAFEMS Seminar “Component and System Analysis Using Numerical Simulation Techniques- FEA, CFD, MBS”
23 – 24 November, 2005 | Gothenburg, Sweden
• Design Tools: CAD modeling• FEA Pre&Post processing• Stress analysis tools• MBS “Loads generation tools”• VPD based fatigue analysis
-Historically each “station” implied separate departments, different software environments and unidirectional dialogue
-Modern trends command a tight integration and seamless flow, as in the case of component modal synthesis to abridge FEA to MBS
CAD FEA PRE-POST FEA STRESSES MBS FEA FATIGUE
NAFEMS Seminar “Component and System Analysis Using Numerical Simulation Techniques- FEA, CFD, MBS”
23 – 24 November, 2005 | Gothenburg, Sweden
Geometry and mesh
MSC.Patran
Mode shape analysis
MSC.Nastran
FEA PRE-POST FEA STRESSES
Solution path with Component modal synthesis
NAFEMS Seminar “Component and System Analysis Using Numerical Simulation Techniques- FEA, CFD, MBS”
23 – 24 November, 2005 | Gothenburg, Sweden
Component modal synthesis – Craig-Bampton Method
Partitioning the structure into internal and boundary DOFs:
Boundary DOFs (b)
Internal DOFs (i)
Boundary DOF’s are DOF’s of the nodes where the flexible body is connected to therest of the system, not necessarily geometry boundaries of the body. Boundary nodesNeed to be defined by user.
ffffffffff FuKuBuM =++ &&&
≅ ≅ ≅ ≅ Φq
Approximating the physical coordinates ui and ubwith their modal summation:
N
C
MC
bb
i
b
q
qoI
u
u
ΦΦ
{ }
=
= ii
b
NC
bb
i
bf u
uoI
u
uu
ΦΦ
≅≅≅≅
response to boundary displacements
fixed-boundary modal expansion
NAFEMS Seminar “Component and System Analysis Using Numerical Simulation Techniques- FEA, CFD, MBS”
23 – 24 November, 2005 | Gothenburg, Sweden
Geometry and mesh
MSC.Patran
Fatigue life calculation
Load histories
Mode shape analysis
System-level simulation
Mode shapes
Stress shapes
MSC.Nastran MSC.FatigueMSC.ADAMS
FEA PRE-POST FEA STRESSES MBS FEA FATIGUE
Strain Life Plot
605M30Sf': 857 b: -0.067 Ef': 0.636 c: -0.579
1E-3
1E-2
1E-1
Str
ain
Am
plit
ud
e
(M/M
)
1E0 1E1 1E2 1E3 1E4 1E5 1E6 1E7 1E8Life (Reversals)
0
1574.7 -750.4
808.70
4.8548
RangeuE
X-Axis
MeanuEY-Axis
DamageZ-Axis
DAMAGE HISTOGRAM DISTRIBUTIONMaximum height : 4.8548Z Units : %
Solution path with Component modal synthesis
NAFEMS Seminar “Component and System Analysis Using Numerical Simulation Techniques- FEA, CFD, MBS”
23 – 24 November, 2005 | Gothenburg, Sweden
Crankshaft design: Problem description and size
• Background• Assessment of Critical engine speeds through fatigue factor of
safety• Need for rapid prototyping and data retrieving• Using MSC.Nastran and MSC.Adams/Engine
• Basic requirements for Virtual Prototyping• Adequate Stress resolution • Inspect the complete operational speed range • Solve dynamic transient analysis with high angle reso lution
• Virtual Product Development solution• high FE mesh refinement with model of >500K nodes• Inspect the operational speed range with 100 rpm incre ments• Perform MBS modal transient analysis with FEA Flexibl e bodies• Modal stress recovery with 2 degree (or more) resolution angle
NAFEMS Seminar “Component and System Analysis Using Numerical Simulation Techniques- FEA, CFD, MBS”
23 – 24 November, 2005 | Gothenburg, Sweden
Auto Mesh Boundary nodes identification
Multi point Constraint (e.g. RBE3 and RBE2 in MSC.Nastran )
Manual, tedious, very error prone, risk of inconsistency: requires automation
CMS - modal reduction on large models
hotspot generation
Produces a results deck or several GB if all deformation and stress vectors are requested.
Requires focus
Engine run up analysis to cover all rpm range
Produces a Set of Modal Participation factors at each RPM (~50 sets)
Needs solution strategy and clever file handling
CAD FEA PRE-POST FEA STRESSES MBS FEA FATIGUE
Stress recovery and multiaxialFactor of safety for each engine speed (i.e. ~50 large fatigue jobs)
Screams for automation, efficient data handling and reporting
The required process for Crankshaft design would take s everal weeks to solve and would require immense system resource s!
Solution path to satisfy crankshaft design requirem ents:
NAFEMS Seminar “Component and System Analysis Using Numerical Simulation Techniques- FEA, CFD, MBS”
23 – 24 November, 2005 | Gothenburg, Sweden
the proposed efficient solution for Crankshaft desi gn:
• Preprocessing• Eliminate the manual, error prone tedious model
preparation• Reduce the model size by focusing on the assumed cri tical
areas
• Solving• Drive the MBS solver to maximize speed and data retriev al • Automate the subsequent multiple multiaxial fatigue
analyses
• Reporting• Automatically identify the most critical speed and relative
location
NAFEMS Seminar “Component and System Analysis Using Numerical Simulation Techniques- FEA, CFD, MBS”
23 – 24 November, 2005 | Gothenburg, Sweden
Craig-Bamptonmodes
Modal Stresses
For every modal vector, Stress concentrate around the Bearings
Stress analysis can conveniently be reduced to the “hot spots areas” to achieve great reduction of CPU time and disk space
A justification for a reduction to critical areas
NAFEMS Seminar “Component and System Analysis Using Numerical Simulation Techniques- FEA, CFD, MBS”
23 – 24 November, 2005 | Gothenburg, Sweden
A justification for a reduction to critical areas
NAFEMS Seminar “Component and System Analysis Using Numerical Simulation Techniques- FEA, CFD, MBS”
23 – 24 November, 2005 | Gothenburg, Sweden
FEM-Flex ModelsPart/ Meshes
Load Cases
Pre-Processing Reporting
AUTOMATION
SOL 103 +Nastran DMAP-Ishell
Individual subregion ofOp2 orthogonal stresses
Solving for Nastran-Adams-Fatigue
Modal data
Data Transfer
Proposed simulation workflow: no missing links!
NAFEMS Seminar “Component and System Analysis Using Numerical Simulation Techniques- FEA, CFD, MBS”
23 – 24 November, 2005 | Gothenburg, Sweden
Pre-Processing
NAFEMS Seminar “Component and System Analysis Using Numerical Simulation Techniques- FEA, CFD, MBS”
23 – 24 November, 2005 | Gothenburg, Sweden
Pre-Processing
SOL 103 +Nastran DMAP-Ishell
Op2 orthogonal stresses for Individual hotspots
Solving for Nastran
NAFEMS Seminar “Component and System Analysis Using Numerical Simulation Techniques- FEA, CFD, MBS”
23 – 24 November, 2005 | Gothenburg, Sweden
Solving for Adams
• MSC.Adams is run in a single transient analysis spanni ng the whole operational rpm range using the following seque nce:• Settling time 5 to 10 Revolutions• Rpm_increase (by 100 rmp) 1 to 2 Revolutions• Output only 2 full revolutions at each measurement
• Parallel Processing implies simply distributing rpm rang es• CPU 1 from 1 to n_i Rpm• CPU 2 from n_i+1 to n_j Rpm
NAFEMS Seminar “Component and System Analysis Using Numerical Simulation Techniques- FEA, CFD, MBS”
23 – 24 November, 2005 | Gothenburg, Sweden
All Modal data is stored a single file !!
Engine Fatigue Toolkit• Input
• ADAMS results data• Hot spots• Orthogonal Stress
Vectors• Fast Modal Stress recovery
and Fatigue Analysis• High cycle fatigue• Multiaxial Dang Van
Criterion• Automatic Output
• Factor of Safety as a function of Rpm
Individual Op2 withOrthogonal modal stresses
Solving for Fatigue
NAFEMS Seminar “Component and System Analysis Using Numerical Simulation Techniques- FEA, CFD, MBS”
23 – 24 November, 2005 | Gothenburg, Sweden
Reporting
Engine Fatigue Toolkit• Each hotspot region
analyzed independently
• Factor of Safety as a function of Rpm is output interactively
• 6 curves above represent results from 200+multiaxia fatigue runs
• Full FEA Fatigue results information can optionally stored and be manually retrieved
NAFEMS Seminar “Component and System Analysis Using Numerical Simulation Techniques- FEA, CFD, MBS”
23 – 24 November, 2005 | Gothenburg, Sweden
FEM-Flex ModelsPart/ Meshes
Load Cases
Pre-Processing Reporting
AUTOMATION
SOL 103 +Nastran DMAP-Ishell
Individual subregion ofOp2 orthogonal stresses
Solving for Nastran-Adams-Fatigue
Modal data
Data Transfer
NAFEMS Seminar “Component and System Analysis Using Numerical Simulation Techniques- FEA, CFD, MBS”
23 – 24 November, 2005 | Gothenburg, Sweden
Experiences
• Preprocessing time in both Nastran and Adams/engine has been virtually eliminated
• Solving time for Adams/Engine less then a day, with the option for linear improvement for parallel
• Fatigue solution time is a matter of minutes for each hotspot and rpm. The full engine operational range can be assesse d in 1 or 2days
• The whole design cycle for a basic engine variation c an be carried in 5 to 10 days (possibly 2 to 3 weeks for a redesig n)
• The quality or the results is not affected by the fas t process; actually it is benefiting from the added dimension in sensitivity• FEM element type (Solid Vs. surface, nodal Vs. elem ent)• Analysis variables such as Damping or modal truncat ion• Fatigue parameters to account for Stress gradients, hardening,
surface treatment, material condition etc..
NAFEMS Seminar “Component and System Analysis Using Numerical Simulation Techniques- FEA, CFD, MBS”
23 – 24 November, 2005 | Gothenburg, Sweden
In the quest for automation…
• Evident benefit of automation• Leverage commercial software• Identify risk factors fast and early• Remove errors and tedious repeatable tasks• Encapsulate knowledge
• NOT so evident benefits• Stochastic assessment• Solution Robustness• Data Efficiency
• handling, analysis and storing• Sharing, retrieving and transport across network
NAFEMS Seminar “Component and System Analysis Using Numerical Simulation Techniques- FEA, CFD, MBS”
23 – 24 November, 2005 | Gothenburg, Sweden
Fatigue Analysis vs. Fatigue Testing*Fatigue Analysis vs. Fatigue Testing*
Distribution of FE results
Distribution of test results
Single test result
Single FE result
Life results300 hours100 hours
any fatigue life specified must also be linked to a particular confidence level
*courtesy of Dr Neil Bishop of Random Loading Limited
NAFEMS Seminar “Component and System Analysis Using Numerical Simulation Techniques- FEA, CFD, MBS”
23 – 24 November, 2005 | Gothenburg, Sweden
Conclusions
• In complex problem such crankshaft design, a clever strategy supported by relatively simple programming can leverage well established off the shelf solutio ns to provide relevant enhancements, such as solution speed, results robustness and data handling
• Despite the seemingly unstoppable increase of solution power and system resources, engineering skills are still preferred to brute force
• Automation in solution processes and data handling is line with the vision and the need to manage data no t just producing it. This is becoming crucial as Terabytes of results are continuously produced and shared across deparments.
NAFEMS Seminar “Component and System Analysis Using Numerical Simulation Techniques- FEA, CFD, MBS”
23 – 24 November, 2005 | Gothenburg, Sweden
Thank you!