FEA Presentation - PowerPoint PPT Presentation

1 / 22
About This Presentation
Title:

FEA Presentation

Description:

CAD/CAE applications used: Solid Edge, Hypermesh, LS- Dyna ... Generated H meshes for Pro/E models and applied boundary conditions. ... – PowerPoint PPT presentation

Number of Views:1320
Avg rating:3.0/5.0
Slides: 23
Provided by: prasad3
Category:
Tags: fea | ls | models | presentation

less

Transcript and Presenter's Notes

Title: FEA Presentation


1
PRASAD PETKAR FEA Engineer, QA PTC - Simulation
Products Division
2
Education
3
Computer Aided Design Experience
  • Three years experience with Pro/Engineer
    (Versions 2001, Wildfire,
  • Wildfire 2.0)
  • Part and assembly modeling experience in Pro/E
    using standard and
  • advanced feature creation techniques,
    simplified reps, family tables,
  • skeletons, shrink wraps etc.
  • Worked on Pro/Sheetmetal, Pro/E (Behavioral
    modeler extension)
  • Worked on Product Data Management (PDM)
    software,
  • Pro/Intralink, to verify seamless management
    of Pro/E and
  • Mechanica files
  • Familiar with other CAD software packages Solid
    Edge, SolidWorks

4
Finite Element Analysis Experience
  • Pro/Mechanica (Structure/Thermal) Three years
    extensive experience with
  • Pro/Mechanica, CAE software integrated in
    Pro/Engineer. Various Structural/Thermal
  • Analyses performed were
  • Static Analysis to compute stresses and
    displacements
  • Contact analysis to compute contact forces,
    stresses and load transfer through contact area
  • Buckling analysis to calculate critical buckling
    loads for the structure
  • Large deformation static analysis
  • Pre-stress static analysis
  • Modal analysis to calculate free and constrained
    natural frequencies
  • Vibration analysis including dynamic frequency,
    time, random and shock
  • Steady state and Transient thermal analysis

Contd
5
Finite Element Analysis Experience
  • Pro/Mechanica FEM mode (Pre and post processor
    for 3rd party solvers viz.
  • Nastran and Ansys)
  • Generated H meshes for Pro/E models and
    applied boundary conditions.
  • Verified accuracy of exported mesh elements
    and properties associated to
  • it in pre-processor output decks. Verified
    accuracy of post processed
  • solution by displaying fringe plots and
    result graphs.
  • HyperMesh
  • Used HyperMesh to mesh solid models of seat
    and head restraint
  • created in Solid Edge as part of graduate
    research.
  • LS- DYNA
  • Used LS- DYNA to to perform non-linear crash
    analysis to analyze
  • effectiveness of seat and restraint systems
    for occupant protection for rear
  • impact crash situation. LS- DYNA was combined
    with rigid body dynamics
  • software to generate human dummy model to
    provide complete crash
  • environment.

6
Structural Analysis Responsibilities
  • As an FEA Engineer in Quality Assurance
    Department of PTCs simulation
  • products division, functions performed were
  • Designed and modeled various parts and assemblies
    using standard and advanced feature creation
    techniques, simplified reps and family tables
  • Assigned materials to components. Modeled various
    idealizations viz. beams, shells, masses,
    springs, midsurface compressed shells etc. to set
    up finite element model
  • Defined various connections viz. edge/perimeter
    welds, spot welds, bolt/screw fasteners to
    connect components in an assembly
  • Set various structural boundary conditions viz.
    surface loads, pressure loads, bearing loads,
    surface constraints etc.
  • Defined various displacement/stress measures at
    datum points in the model to obtain specific
    numerical results
  • Post processed fringe results for stress/
    displacements to visualize
  • structure behavior.
  • contd

7
Structural Analysis Responsibilities
  • Identified structure failure for applied load
    based on different material failure
  • criterion by plotting failure index fringe
    plots.
  • Plotted graphs of measures to obtain critical
    stress/displacement values
  • Performed hand-calculations to verify accuracy
    of numerical results for
  • simple models with closed form solutions
  • Verified stress/displacement behavior for more
    complex models by making
  • logical sense of results in absence of closed
    form solution
  • Performed local/global sensitivity studies by
    varying design sensitivity
  • parameters over a range and viewing graphs of
    desired outputs viz.
  • stress/displacement measures as function of
    the parameters
  • Performed design optimizations for design goal
    in terms cost, mass, displacement,
  • stress etc by specifying multiple design
    parameters and constraints
  • Filed performance issue reports in case of
    result inaccuracy or analysis
  • failure. Followed up on the issues to get it
    fixed
  • Following slides show sample of various models
    created and analyzed.

8
Fastener Connections
  • In Pro/Mechanica Wildfire 2.0 release, Fastener
    connection is being introduced. Designed various
    assembly models connected by bolt Fasteners.

Shaft flanges bolted together to carry
tensional loads
Brackets bolted together by plates
Contd
9
Fastener Connections
Pressurized vessel capped by pressure plate
bolted at the end
Load carrying bracket bolted to the wall
10
Fastener Connections Meshing
  • Meshed assemblies using AutoGEM. Verified that
    correct regions corresponding to contact area of
    bolt head and nut are getting meshed around bolt
    holes.

In Mechanica Wildfire version, elements in the
model can be viewed in Pro/Mechanica Integrated
mode. Have extensively worked to implement this
functionality by verifying successful meshing for
various 3D and 2D complex solid, shell and mixed
models.
11
Fastener Connections Result verification
  • Plotted stress fringe plots for the models and
    verified that load is not transferred through
    mated geometry and is transferred only through
    fasteners.

Contd
12
Fastener Connections Result verification
New Mechanica measures were introduced to
calculate various quantities for each bolt
connection. Plotted various measure graphs for
shear stress/force, tensile stress/force carried
by each bolt and performed hand calculations to
verify numerical values. Verified that
shear/tensile stresses in the bolts do not exceed
allowable values. Performed sensitivity studies
to visualize effect of various design parameters
viz. bolt diameter, hole location etc. on various
bolt measures and whole model. Performed
optimization to obtain minimum bolt diameter for
given allowable stress by varying model
dimensions.
Fastener Shear Stress Vs. P-loop pass
Fastener Shear Force Vs. P loop pass
13
Assembly Links
  • In Mechanica 2001, automatic assembly links were
    introduced to connect midsurface compressed shell
    parts mated together. Extensively tested this
    functionality to verify element linkage at mated
    interface.

Presence of assembly links is validated by
structural analysis as both the parts are
displaced together when load is applied to only
bottom part.
Two shell compressed parts are mated leading to
generation of automatic assembly link at mated
interface.
14
Free connections
  • Free connection were introduced in Wildfire
    release to selectively delete automatic assembly
    links between mated midsurface shell parts.
    Verified that assembly links do not get created
    at free interface definition.

Presence of free connections is validated by
structural analysis as only bottom part which is
loaded is displaced keeping top part undeformed.
Free connections defined at mated interfaces of
previous parts using surface regions.
15
Buckling Analysis
  • Buckling analysis is used in design of axially
    loaded compression members which are relatively
    slender. Performed buckling analysis to calculate
    critical load using BLF and verified accuracy of
    calculations.

Buckling of axially loaded support structure.
Fringe plots show first 2 buckling
modes. Calculated buckling load factors (BLF)
were 1.41, 5.25, 8.57.. leading to conclusion
that critical load at which structure will fail
by buckling is 1.41 times applied load.
To vary/reduce
critical load, performed sensitivity analysis
with structure height and c/s area as parameters
to visualize effect of slenderness ratio on BLF,
i.e. critical load.
16
Contact Analysis Seat belt
Structural contact analysis is used to solve
design problems when parts come in contact but
exact contact region is unknown. Performed
contact analysis for seat buckle and clip
assembly to find contact stresses and pressures.
Seat-buckle and clip assembly with contact
regions and boundary conditions defined.
Fringe plot of contact pressure distribution for
belt and clip parts.
Evaluated contact stresses to check if they
exceed material yield stress, which signifies
failure of material in contact by crack/flaking
in area of contact. Also checked if stresses
do not exceed allowable value in any other part
of the model.
17
AutoGEM Mesh Controls
  • In Wildfire 2.0, AutoGEM mesh control
    functionality is added to give user more control
    over element/node distribution and element count.
    Verified effectiveness of this functionality by
    meshing various 2D and 3D complex models for
    various control settings.

Minimum element edge control to ignore small
edges/curves below specified element edge length.
Primary use is to ignore small cosmetic features
while meshing thus significantly reducing element
count.
Edge distribution control to specify number of
element edges along selected curve. Primary use
is to easily refine mesh density in area of
interest (contact, high stress etc.) to increase
result accuracy.
18
Stress Analysis of Engine Block
Meshed and performed stress analysis on complex
customer Engine block model.
19
Graduate Research Project
Design and analysis of seat and head restraint
system for occupant protection In rear impact
crash simulation.
Meshed 3D seat model with seatbelt.
Contd
20
Graduate Research Project
Simulation run in LS-DYNA and ATB ( Articulated
Total Body) coupled software. Non linear seat
material (low-density foam) and vehicle motion
defined in LS-DYNA. Human dummy generated in
ATB. Analyzed effect of various seat design
factors on head motion leading to neck injury.
21
Conclusion Relevance
  • 4 years experience with various CAD/FEA
    software tools.
  • Experience in effectively performing
    structural/thermal finite
  • element analysis by specifying boundary
    conditions to validating
  • results using hand calculations and result
    plots.
  • Excellent written and oral communication skills
    gained through
  • interaction with customer Engineers,
    technical-marketing, product
  • development team and through creating reports
    to document test
  • results and software issues.
  • Good project management and multitasking skills
    obtained by
  • working simultaneously on diverse
    time-sensitive projects.

22
Thank You
Write a Comment
User Comments (0)
About PowerShow.com