2018 ncode user group meeting –north america | february 28
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2018 nCode User Group Meeting – North America | February 28 – March 1
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Identification and Analysis of Critical Time Slices
Based on Damage Time History
Ken Citrin
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• Mahindra Automotive North America (MANA) was founded in 2013• Headquarters of Mahindra Group’s Automotive operations in North America
• 300+ automotive professionals
• $230 million invested in Southeast MI
• The first new automotive OEM to set up manufacturing in Southeast Michigan in 25‐years
• Facilities in Auburn Hills, Pontiac and Troy• MANA spans 400,000 ft2 across Metro Detroit
• Operations are ramping up• Forthcoming release of our first off‐highway vehicle
• Will add 400 jobs and invest another $600 million in the local economy by 2020
Mahindra Automotive North America
Auburn Hills
Pontiac
Troy
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• The North American automotive industry predicts component life from acquired load time histories
• Analysis output is a scalar value • Does not provide insight into which events are the primary contributors
• Analysis of discrete time slices are used to develop countermeasures• Identifying the damaging events
• Imprecise
• Time consuming
Identify Damaging Time Slices for Component Analysis
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• A GlyphWorks flow has been developed to aid identification of the major contributors to fatigue damage
• Events that occur infrequently with high damage
• Events that occur frequently with high cumulative damage
• A GlyphWorks flow has been developed to create the FEA data deck cards• Cards had been created manually
• Time consuming
• Error prone
• These processes have increased productivity and confidence
Using GlyphWorks for Time Slice Identification
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Challenge Solution
Summary
Results
Identify critical time slices for component analysis
Export the time slices into the FEA
GlyphWorks processes are used to identify specific events based on damage and cycle counts
GlyphWorks extracts the loads at the selected time slice and writes bulk data deck cards for the FEA
Greater insight into component performanceIncreased efficiencyReduced errors
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7Process Overview
Hot Spot Identification
Strain/Time History
Damage/Time History
Damage Rainflow Cycle
Count
Tabulated Damage by
Cycle
Select Time Slice
Extract Load Channels
Write NASTRAN Bulk Data Deck
Cards
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• Conduct component life analysis• Current methods
• Stress/Life
• Strain/Life
• Seam Weld
• Spot Weld
• Identify critical locations• Select one element at each location
• Reduces amount of data to process
Identify Critical Areas
Hot Spot Identification
Strain/Time History
Damage/Time History
Damage Rainflow Cycle
Count
Tabulated Damage by CycleSelect Time SliceExtract Load
Channels
Write NASTRAN Bulk Data Deck
Cards
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9Identify Critical Locations
Identify Hot Spots Select 1 Element per Hot Spot
Perform Component Life Analysis
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• Desired information is damage/time history• Not Available in Design Life modules
• Future Enhancement?
• Is available from GlyphWorks modules
• Output the strain/time history• These are elastic strains
• Add output pipe to Design Life analysis glyph
• Connect to a time series output glyph
• Rerun component life analysis• Selected elements only
Recover Nodal Strain/Time History
Hot Spot Identification
Strain/Time History
Damage/Time History
Damage Rainflow Cycle
Count
Tabulated Damage by CycleSelect Time SliceExtract Load
Channels
Write NASTRAN Bulk Data Deck
Cards
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• 1st of a 2‐Step Process
• Create a GlyphWorks damage calculation• Replicate Design Life analysis in GlyphWorks
• Confirm life at Hot Spots are replicated
• Output• Time correlated damage
Develop Time Correlated Damage
Hot Spot Identification
Stress/Time History
Damage/Time History
Damage Rainflow Cycle
Count
Tabulated Damage by CycleSelect Time SliceExtract Load
Channels
Write NASTRAN Bulk Data Deck
Cards
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12Time Correlated Damage
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• Damage is associated with strain cycles• ½‐Damage is assigned to cycle opening
• ½‐Damage is assigned to cycle closing
Time Correlated Damage
Damage/Time History, Location #1
Elastic Strain/Time History, Location #1
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• Output• Damage histogram
• Strain histogram
Damage by Cycle
Hot Spot Identification
Stress/Time History
Damage/Time History
Damage Rainflow Cycle
Count
Tabulated Damage by CycleSelect Time SliceExtract Load
Channels
Write NASTRAN Bulk Data Deck
Cards
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• Associates Damage with Number of Occurrences• Highest damage due to 3 repeats
• Highest strain range causes near highest damage
Damage & Strain Histogram
Elastic Strain Histogram, Location #1
Damage Histogram, Location #1
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• Output• Damage by cycle
• Cycle opening point
• Cycle closing point
Damage by Cycle
Hot Spot Identification
Stress/Time History
Damage/Time History
Damage Rainflow Cycle
Count
Tabulated Damage by CycleSelect Time SliceExtract Load
Channels
Write NASTRAN Bulk Data Deck
Cards
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17Cycles are Ranked by Damage
Cycle Opening
Cycle Closing
Damage from Cycle
Sample Rate
50% of Damage From Only 40 Load Cycles
Two cycles have equivalent damageRepresents 2 repeats of same event
Total damage for event is doubledRanking of cycle is moved higher
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• Identify time slices of interest• Cycles of interest
• Opening point
• Closing point
• Remove duplicate time slices• Represents repeats of an event
• By channel
• Select time slice for each critical location
• Merge slice points from all critical locations• Remove duplicate slices
Select Time Slices for Analysis
Hot Spot Identification
Stress/Time History
Damage/Time History
Damage Rainflow Cycle
Count
Tabulated Damage by
Cycle
Select Time Slice
Extract Load Channels
Write NASTRAN Bulk Data Deck Cards
ChanNumber srate pmax pmin damage2 500 237,761 237,875 0.0004432 500 1,419,848 1,557,322 0.0003422 500 1,417,024 1,417,528 0.0003272 500 406,062 411,951 0.000322 500 409,785 406,162 0.000311
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• 2nd Step of a 2‐step process
• Extract loads from time history• Feature list
• Simultaneous values
Extract Loads to Apply to Finite Element Model
Hot Spot Identification
Stress/Time History
Damage/Time History
Damage Rainflow Cycle
Count
Tabulated Damage by CycleSelect Time SliceExtract Load
Channels
Write NASTRAN Bulk Data Deck
Cards
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• Input• Element strain/time history
• Slice points
• FEA load/time history
• Output• Simultaneous channel values
• Each time slice
• Format is not compatible with FEA
Extract Loads for Finite Element Analysis
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• Write NASTRAN bulk data deck cards• Eliminates manual card image creation
• nCode Support developed the SuperGlyph
• Input• FEA load/time history
• FEA load mapping
• Time slices
• Output• NASTRAN Case Control deck cards
• NASTRAN Bulk Data deck cards
Process Loads for FEA Input
Hot Spot Identification
Stress/Time History
Damage/Time History
Damage Rainflow Cycle
Count
Tabulated Damage by CycleSelect Time SliceExtract Load
Channels
Write NASTRAN Bulk Data Deck
Cards
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• FEA load/time history
• Time Slices
• FEA Load Mapping
Input
Channel Number
Node ID Component Coord Sys
ChanNum NodeID Component CoordSys
long long string long
1 1 FX 02 1 FY 03 1 FZ 04 1 MX 05 1 MY 06 1 MZ 07 2 FX 08 2 FY 09 2 FZ 0
10 3 FX 011 3 FY 012 3 FZ 013 3 MX 014 3 MY 015 3 MZ 0
Slice # Element Number Slice (time) Slice (point)1 2 475.520 237,7612 2 2,839.694 1,419,8483 2 2,834.046 1,417,0244 2 812.122 406,0625 2 819.568 409,7856 2 475.748 237,8757 2 3,114.642 1,557,3228 2 2,835.054 1,417,5289 2 823.900 411,95110 2 812.322 406,162
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• NASTRAN Case Control Deck • NASTRAN Bulk Data Deck
Output
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www.hbmprenscia.com
Kenneth M. Citrin Paul Green
CAE Engineering, MANA HBM Prenscia
248‐417‐8219 248‐945‐4340