Transcript EP_status-presentation_1_Nick_Aiello.pptx

Thermo-Mechanical Fatigue
Optimization of Three Dimensional
Stress Concentration Features in a
Tangentially Bladed Rotor
by
Nicholas D. Aiello
Project Overview
Project broken into 3 parts:
• Part 1: Baseline design 3D model
• Create 3D CAD model of slot area in NX
• Mesh model in ANSYS
• Apply boundary conditions and interface definition
• Run and post process results
• Part 2: 2D optimization routine
• Create 2D CAD plate model of slot area in NX
• Determine 2D-3D stress factors for each mission point using 3D model and TMF lifing file
• Vary thickness of plane stress elements to replicate 2D-3D stress factors at each mission point
• Create iSight DOE to map effect of change of slot shape on TMF life of slots
• Review DOE map to determine optimal solution that meets design constraints
• Part 3: Result verification 3D model
• Create 3D model of optimized geometry
• Repeat steps from part 1
• Compare stress concentrations predicted by 2D model to 3D results
Geometry Summary
3D rotor model created
• 3D model includes upper portion
of disk web and full disk rim area
• 3D stress concentration features
are load slots, lock slots, and shield
slots
• Model is cut up for ease of
meshing/applying BC’s in ANSYS
Mesh Summary
Blade Definition
•
•
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Model meshed using 3 types of 3D
elements
1. 10 node tetrahedron: for the complex
geometry of the area surrounding the 3D
slots
2. 8 node brick: for axi-symmetric portions of
the disk to help keep the element count
down/increase run speed
3. 20 node brick: collapse to form the pyramid
shaped elements that connect the other 2
element types
Blade “stump” used to model correct
interface with disk
Mass point at CG represents the upper
portion of the blade
Stiff, massless spring elements
connect mass points to blade stumps
Boundary Condition Summary
Mapped/cut boundaries
• Nodes exported from 3D FE mesh
• Exported nodes compressed onto mid-plane, file created for
use in thermal mapping
• Compressed mid-plane nodes not on cut boundaries
deleted, additional file created for mapping displacements on
model boundaries
Other boundaries/interfaces
• Contact elements used for blade stub to disk interface
• Blades constrained for no circumferential motion
• “Roller” constraints applied to disk sector boundaries