FEM (MSC.NastranSOL600) and Multibody (MSC ...pages.mscsoftware.com/rs/mscsoftware/images...FEM...
Transcript of FEM (MSC.NastranSOL600) and Multibody (MSC ...pages.mscsoftware.com/rs/mscsoftware/images...FEM...
FEM (MSC.Nastran SOL600) and Multibody(MSC.Adams flexible contact) solutions: an application example in helicopter rotor analysis
Daniele CatelaniMSC. Software - EMEA Aerospace Consultant
Francesca BianchiAgustaWestland – Structural Analyst Rotor Department
Stefano Orzi
Politecnico di Milano
FEM (MSC.Nastran SOL600) and Multibody(MSC.Adams flexible contact) solutions: an application example in helicopter rotor analysis
Daniele CatelaniMSC. Software - EMEA Aerospace Consultant
Francesca BianchiAgustaWestland – Structural Analyst Rotor Department
Stefano Orzi
Politecnico di Milano
• Contact analysis into model with flexible bodies
� Available technologies
� MSC.Nastran SOL600 (Marc embedded technology)
� MSC.Adams Flex2Flex contact feature
� Comparison between SOL600 and Adams
� Comparison and validation with Experimental Tests
• Example: Helicopter Tail Rotor control chain
• Workflow
� FEM model for experimental results correlation and validation
� Adams flex model
� correlation with SOL600
� DOE for parameters tuning and validation
� Model Improvements:
� full kinematic and flexible model
� Dynamic, transient analysis implementation
� DOE for design also
Introduction
Bushing
Pitch control Beam
Ring
Actuator shaft
2
• Helicopter Tail Rotor provides Thrust to compensate Main Rotor Torque
• Control chain allows the pilot to change the blade pitch and - consequently –to control the Thrust
• Control chain: assembly of moving parts mechanichally joined together, involving CONTACTS btw parts
• Control chain Stiffness has to be known for dynamic assessments
• Stiffness needs to be evaluated for different control configurations
• Evaluation is performed by test and by analysis on simplified models
It is evident the importance of a simulation tool
� well correlated wrt experimental results
� to be used for preliminary design
� because allows quick changes of control configuration (i.e. pilot control input)
Tail rotor: problem description
More than words….
Experimental tests
0 0.2 0.4 0.6 0.8 1-1
-0.8
-0.6
-0.4
-0.2
0
Carico [UMF]
Mom
ento
flet
tent
e [U
MM
]
Momento flettente - Prova sperimentale
←←←←-18911
←←←←-0.31872
BB1prlBB2prl
0 0.2 0.4 0.6 0.8 1-3
-2.5
-2
-1.5
-1
-0.5
0
Carico [UMF]
Mom
ento
flet
tent
e [U
MM
]
Momento flettente - Prova sperimentale
←←←←-0.31956
←←←←-0.1888
BB1prlBB2prl
• Scope
� Identify tail rotor control chain stiffness
� Evaluate coupling effect btw actuator shaft and bushing
� Identify CONTACT characteristics
• Equipment
� Actuators to apply the loads (statically and dynamically)
� Displacement transducers to measure the displacements at proper locations (i.e. Along the shaft and on the pitchcontrol beam)
� Strain gauges to study the load paths
� A proper rig allowing the control chain installation withoriginal parts
• Tests
� Collective and cyclic loads
• Results
� Test Data Post-processing allows the calculation of the control chain stiffness for subsequent dynamic assessments: bending moment/load curves shows the effect of contact btwbushing, ring and shaft
Bushing
Pitch control Beam
Actuator shaft
Ring
• Analysis
� SOL600 uses already existing Nastran bdf file (FEM data)
� All bodies modelled with solid elements (HEXA)
� Local Mesh Refinement for contact and stress evaluation
� Different materials are considered
� Rigid element for loads and constraints
� Applied loading conditions to reproduce physical tests
� Five contact bodies defined (“touched” and “glue” types)
� Deformable – deformable contact
� Parameters/Solution tuning
� Contact detection
� Tolerance parameters
� Bias distance
� Contact body/surface definition: Master/Slave
� The contacts mainly affecting the stiffness results are:
� actuator shaft – bushing installed in the power shaft
� actuator shaft – ring installed in the power shaft
SOL600 analysis
• Static analysis performed on the most complex sub-partof the assembly (pitch beam), properly clamped, forverifying correlation with experimental stiffness
• Static analysis to simulate the full control chain stiffnesstests: 2 configurations of the assembly are considered
� Max pitch
� Min pitch
� Note 1: No Analysis with time–dependent loads(performed in the lab test)
� Note 2: No Analysis with time-dependent changeof the assembly configuration and rotating shaft(performed with Adams)
� Note 3: CPU time to complete one SOl600 run on high performance multi-processors hardware : ~2 hours
SOL600 analysis
Sperimentale[UMR]
Analitica[UMR]
Carico positivo
1.028
1.0001.0270.954
Media 1.003Delta % 0.46
Carico negativo
0.979
1.0000.9850.976
Media 0.980Delta % 0.24
2.5 2.5
0 0.2 0.4 0.6 0.8 1
-1
-0.8
-0.6
-0.4
-0.2
0
Carico [UMF]
Spo
stam
ento
[UM
S]
Collettivo - LVDT5/8 - direzione Y - Complessivo
LVDT5LVDT6LVDT7LVDT8
0 0.2 0.4 0.6 0.8 1
-1
-0.8
-0.6
-0.4
-0.2
0
Carico [UMF]
Spo
stam
ento
[UM
S]
Ciclico - LVDT5 LVDT6 LVDT7 LVDT8
LVDT5LVDT6LVDT7LVDT8
• A few correlation OUTPUT chosen:
� Bending bridges reading the flexural moments along the actuator shaft
� Displacement transducers to compute the chain stiffness
• VERY GOOD final correlation wrt flexuralmoments and displacements after some tuning:
� Changing the “glue” contact with the pitch control beam on top of the actuator shaft: rigid bars have been used
� Resizing the gap between the actuator shaft and the bushing
• VERY SMALL final differences btw Test and SOL600:
� about 1% on the pitch control beam displacements
Correlation with Experimental tests
Numerical Physical
Before GAP changing
After GAP changing
Numerical Physical
0 0.2 0.4 0.6 0.8 1-3
-2.5
-2
-1.5
-1
-0.5
0
Carico [UMF]
Mom
ento
flet
tent
e [U
MM
]
Momento flettente - Prova analitica
BB1prlBB2prl
0 0.2 0.4 0.6 0.8 1-3
-2.5
-2
-1.5
-1
-0.5
0
Carico [UMF]
Mom
ento
flet
tent
e [U
MM
]
Momento flettente - Prova sperimentale
←←←←-0.18911
←←←←-0.31872
BB1prlBB2prl
0 0.2 0.4 0.6 0.8 1-3
-2.5
-2
-1.5
-1
-0.5
0
Carico [UMF]M
omen
to fl
ette
nte
[UM
M]
Momento flettente - Prova analitica
BB1prlBB2prl
0 0.2 0.4 0.6 0.8 1-3
-2.5
-2
-1.5
-1
-0.5
0
Carico [UMF]
Mom
ento
flet
tent
e [U
MM
]
Momento flettente - Prova sperimentale
←←←←-0.31956
←←←←-0.1888
BB1prlBB2prl
• FE beam model for shaft
• 3D flexible model for pitch control beams
• Introduction of Master nodes along the shaft fordefining contact points (discretized contact)
(Vector forces)
• Developed interpolation routine for smoothing the transition between discretized contact
Adams model – Adopted Solution older release
From 3D
to beams
For D(node,ring) = 0 F = FMAX
For D(node,ring) = D(node,node) F = 0
For D(node,ring) < D(node,node) F=f(D)
For D(node,ring) = 0 F = FMAX
For D(node,ring) = D(node,node) F = 0
For D(node,ring) < D(node,node) F=f(D)
• Adams model built from same flexible bodies usedfor SOL600
� shaft
� pitch control beam
� bushing
� Ring
• Introduction of Master nodes for constraints and concentrated loads and cards for SOL103 and MNF generation
• Kinematic model:
� Primitive joints
� Fixed joints
� Motion
• Two contacts regions defined:
� between the shaft and the bushing
� between the shaft and the ring
• Output:
� Displacement
� Loads on constraints
� Nodal loads (FEMDATA)
Adams model – Flex2Flex
Fixed
Primitive
Motion
• Workflow -1
� Submodels for tuning the contact parameters with SOL600:� A submodel shaft + bushing
� A submodel shaft + ring
� Tuning on the basis of the main OUTPUTs, i.e. displacements and forces
� Accurate tuning on Adams contact parameters (K, damp, exp) using DOE analysis and comparison with SOL600
Adams/SOL600 correlation
0 0.2 0.4 0.6 0.8 1-1
-0.8
-0.6
-0.4
-0.2
0
Test Crociera - Spostamento in direzione Y - SOL600
Carico [UMF]
Spo
stam
ento
[UM
S]
Node F1Node F2Node F3Node F4
0 0.2 0.4 0.6 0.8 1-1
-0.8
-0.6
-0.4
-0.2
0
Test Crociera - Spostamento in direzione Y - Adams
Carico [UMF]
Spo
stam
ento
[UM
S]
Node F1Node F2Node F3Node F4
� Submodels for tuning the contact parameters with SOL600:� A submodel shaft + bushing
� A submodel shaft + ring
Adams/SOL600 correlation
• Workflow -2
� Procedure applied to each contact to tune all parameters
� Evaluation of shaft deformation
� Evaluation of nodal loads and reactions
� Evaluation of displacements
Adams/SOL600 correlation
• Workflow -3
� Adams > SOL600:
� CPU time comparison: big advantage for Adams
� Adams allows easy parameterization and DOE analysis
� SOL600 > Adams:
� Adams needs contact parameters tuning and/or identification
� Adams needs solver parameters tuning
� DOE analysis has been useful
� Developed a procedure, using SOL101, for parameter contact identification when SOL600 results not available:
� Simple Nastran models
� Disp vs Applied Load
� Contact parameters estimation and Solver parameterstuning
� Parameters database linked to material
� Adams becomes a tool for prediction not validation only
Adams/SOL600 correlation
• Workflow -4
� Adams > SOL600:
� Adams allows high complexity of the model
� Adams allows transient analysis
Full Model:
� Once tuned ADAMS contact parameters on simplersubmodels, the full assembly has been simulated
� Same outputs used for correlation with experimentalresults: pitch beam displacement and bending moments
� Other outputs for correlation are : shaft deformationshape and reaction forces
� To achieve a good correlation, equivalent modelizationrules have been implemented into Adams and Sol600: rigid elements for the joint between the shaft and the pitch control beam (instead of a “glue” contact, to match experimental results as well)
� As before, two configurations of the control chain havebeen considered:
1. Max pitch
2. Min pitch
Adams/SOL600 correlation
Transient analysis:
Two additional cases studied in ADAMS only to assess the robustness of the described results:
1. Time-constant loads with rotating shaft
2. Time-variable loads (performed in lab tests)
Both cases with continuos change of configuration (frommaximum to minimum)
CPU time analogous to previous simpler analysis
Adams advanced analysis
• Scope of the work:
� Establish feasibility of SOL600 to evaluate/correlate experimental test in a analysis of contact btw flexible bodies
� Establish feasibility of Adams Flexible Contact feature to evaluate/correlate the sameSOL600 test case
• Main results:
� SOL600 vs. Experimental test: very good correlation on a number of significant measuredOUTPUTs
� SOL600 vs. Adams: very good correlation
• Achievements:
� Adams can be adopted as a predictive and design tool together with a database of good and reliable contact parameters
� Robustness of Adams solution has been confirmed by time-variable runs
• Time to complete an Adams run, without friction, is 1/10 of equivalent SOL600 one
Conclusion
• Repeat correlation with MDNastran SOL400
• Exploring friction effects in the contacts
• Extend to more materials the “SOL101” method adopted for the characterisation of Adams contact parameters
• Evaluation on more complex models: introduction of flexible blades, aerodynamic forces, …
Further development/investigation
Thank you