Post on 10-Feb-2017
Oh, The Places You’ll Go! A look at opportunities
available to engineering students and where they may take you.
Presented at: California Space Grant Consortium’s Undergraduate Engineering Seminar Series
University of California, San Diego October 15, 2014
by
Benjamin Martins
University of California, San Diego, La Jolla, CA 92093 blmartin@ucsd.edu
October 15, 2014 2014 California Space Grant Fall Seminar Series 2
Overview
• Introduction
• CASL Undergraduate Research Assistant
• Nano-Reinforced Polymer Composites
• Composite UAV Design and Fabrication
• Active Load Redistribution
• Structural Health Monitoring and Prognosis
• Opportunity Available
• Tips for Success
October 15, 2014 2014 California Space Grant Fall Seminar Series 3
Oh, the places you’ll go!
October 15, 2014 2014 California Space Grant Fall Seminar Series 4
Take Home Messages
• Say Yes!
• Always do your best
• Take opportunity to develop secondary skills
• Stay patient
• Show initiative
October 15, 2014 2014 California Space Grant Fall Seminar Series 5
Overview
• Introduction
• CASL Undergraduate Research Assistant
• Nano-Reinforced Polymer Composites
• Composite UAV Design and Fabrication
• Active Load Redistribution
• Structural Health Monitoring and Prognosis
• Opportunity Available
• Tips for Success
October 15, 2014 2014 California Space Grant Fall Seminar Series 6
F8 Project
October 15, 2014 2014 California Space Grant Fall Seminar Series 7
F8 Project Cont.
0
200
400
600
800
1000
1200
1400
1600
0 50 100 150 200 250 300 350
Time [s]
Load
[N]
0.00E+00
2.00E+08
4.00E+08
6.00E+08
8.00E+08
1.00E+09
1.20E+09
1.40E+09
Cum
ulat
ive
Ener
gy [a
rb]
October 15, 2014 2014 California Space Grant Fall Seminar Series 8
Detecting Damage in Composites
October 15, 2014 2014 California Space Grant Fall Seminar Series 9
Detecting Damage in Composites Cont.
October 15, 2014 2014 California Space Grant Fall Seminar Series 10
Lessons Learned
• Get into a research lab as quickly as you can
• Never think you’re above doing any job
• Always do your best
• You never know where it might lead
October 15, 2014 2014 California Space Grant Fall Seminar Series 11
Overview
• Introduction
• CASL Undergraduate Research Assistant
• Nano-Reinforced Polymer Composites
• Composite UAV Design and Fabrication
• Active Load Redistribution
• Structural Health Monitoring and Prognosis
• Opportunity Available
• Tips for Success
• Conclusions
Motivation
12
• Composite aircraft, rockets, and spacecraft have curved stringers, longerons, isogrid, etc…
• These elements experience combined interlaminar shear and tension
2014 California Space Grant Fall Seminar Series October 15, 2014
Introduction
13
• Composite laminates have outstanding fiber dominated properties
• Poor matrix dominated properties, interlaminar shear and tension
• Industry has tried 3-D stitching, brads, and z-pinning to improve interlaminar shear and tension
• Currently researchers are investigating the use of
carbon nanotubes (CNT) to improve the interlaminar shear strength in prepreg carbon/epoxy laminates 2014 California Space Grant Fall Seminar Series October 15, 2014
Introduction
14
• Vacuum Infused Resin Transfer Molding (V/RTM) and (RTM) are low-cost composite manufacturing approaches that are being used in the General Aviation (GA) industry and the aerospace industry
• Very little published research on the use of CNT’s to improve the interlaminar tension strength properties of V/RTM produced laminates
resin
2014 California Space Grant Fall Seminar Series October 15, 2014
• Current research investigates: • Improvements in interlaminar tension and shear properties in V/RTM
laminates using embedded CNT • CNT’s distributed using two different approaches:
• Metered spray deposition • CNT doped epoxy
• Interlaminar tension studied using modified ASTM standard
Introduction
15
P P P
circle ellipse
Interlaminar Tension
ASTM Methods 2014 California Space Grant Fall Seminar Series October 15, 2014
Specimen Design - Interlaminar Tension - Pure interlaminar
tension stress at apex of ellipse - No shear stress at this
location
- For more information, see: Velazquez, E., and Kosmatka, J.B., "Stresses in a Half-Elliptic Curved Beam Subjected to Transverse Tip Forces," 50th AIAA structures,
dynamics, and materials conference proceedings, Palm Springs, CA, 2009.
16
P
P
2014 California Space Grant Fall Seminar Series October 15, 2014
Specimen Manufacturing - Interlaminar Tension • Metered Spray Deposition Technique
- Carbon Nanotubes (CNTs) sonicated into isopropyl alcohol
- Half of each fabric ply sprayed with CNT/Alcohol Solution
- Laminate vacuum bagged and VARTM infused.
17 2014 California Space Grant Fall Seminar Series October 15, 2014
Specimen Manufacturing - Interlaminar Tension
- Cured semi-elliptical parts sectioned into control and reinforced specimens
- Strain gage placed on inner and outer surface of elliptical sections’ apex
18 2014 California Space Grant Fall Seminar Series October 15, 2014
Specimen Testing - Interlaminar Tension
- Quasi-static load to failure under displacement control
- Loaded at 0.10in/min.
- Strain monitored and recorded on inner and outer surface of elliptical sections apex
P
P
19 2014 California Space Grant Fall Seminar Series October 15, 2014
Results - Interlaminar Tension -Each CNT reinforced part compared to its corresponding control -Strength gains up to 18% -Strength heavily dependent on CNT concentration
20 2014 California Space Grant Fall Seminar Series October 15, 2014
Results - Interlaminar Tension - Interlaminar tensile failure moved
from mid-plane to outside reinforced region.
- Non-linear ILTS allows for targeted reinforcement
- Only treat a key number of plies
- No discernible impact on stiffness
21 2014 California Space Grant Fall Seminar Series October 15, 2014
Specimen Manufacturing - In-Plane Tensile and Shear • Metered Spray Deposition Technique
- In-plane property specimens cut from legs of semi-elliptical sections
Tension Specimens
Shear Specimens
22 2014 California Space Grant Fall Seminar Series October 15, 2014
Results - In-Plane Tensile and Shear
- Tensile coupons show modest gains (~5%) in Young’s moduli (~5%) and decrease in Poisson's ratio (~5.5%)
- Suggests CNTs stiffen in-plane response
- Shear coupons show large gains in Shear moduli (~40-50%%) and failure strain (~15%)
- Alternate test methods needed to validate shear moduli predictions
23 2014 California Space Grant Fall Seminar Series October 15, 2014
October 15, 2014 2014 California Space Grant Fall Seminar Series 24
Lessons Learned
• Once you’ve made it to a research lab, always do you best • You never know when you may get your own project
• Never say never • Experiences you have may change your mind about your future
October 15, 2014 2014 California Space Grant Fall Seminar Series 25
Overview
• Introduction
• CASL Undergraduate Research Assistant
• Nano-Reinforced Polymer Composites
• Composite UAV Design and Fabrication
• Active Load Redistribution
• Structural Health Monitoring and Prognosis
• Opportunity Available
• Tips for Success
• Conclusions
UCSD AUVSI Introduction
October 15, 2014 26 2014 California Space Grant Fall Seminar Series
• Association for Unmanned Vehicle Systems International
• Student organization
• Multidisciplinary • Aerospace Engineering
• Mechanical Engineering
• Structural Engineering
• Electrical Engineering
• Computer Science and Engineering
• Physics
Mission
October 15, 2014 27 2014 California Space Grant Fall Seminar Series
• Build an aircraft capable of: • Autonomous takeoff, navigation, and landing
• Auto-generate search paths through waypoints
• Live imagery
• Optical target recognition
• Remote message reconnaissance
• Remote payload deployment system
• Compete at a 3 day international student competition • Held each June at PAX Naval Air Station, MD
Sub-Teams
October 15, 2014 28 2014 California Space Grant Fall Seminar Series
• Airframe: • Design, analysis and fabrication of aircraft and payload structures
• Mechatronics: • Design and fabrication of all mechanical systems (i.e. camera gimbal, power
bus)
• Embedded: • Development of the hardware architecture related to flight and payload
systems
• Software: • Design and implement code for autonomy, saliency, image recognition, data
downlink, etc…
Airframe: Falco-3
October 15, 2014 29 2014 California Space Grant Fall Seminar Series
• All composite aircraft designed and fabricated by the team • ~10 foot wing span • GTOW of 55lbs
Airframe: Analysis
October 15, 2014 30 2014 California Space Grant Fall Seminar Series
• Modeling with Solidworks and Catia • Structural analysis with FEMAP/NX NASTRAN and Patran/MSC
NASTRAN
Airframe: Fabrication
October 15, 2014 31 2014 California Space Grant Fall Seminar Series
• Custom tooling made by the students • All composite layup
*disclaimer: with balsa stiffeners
Airframe: NextGen
October 15, 2014 32 2014 California Space Grant Fall Seminar Series
• Andross • Fully carbon composite • Detachable payload • Improved aerodynamics
Image Recognition
October 15, 2014 33 2014 California Space Grant Fall Seminar Series
Image Recognition
October 15, 2014 34 2014 California Space Grant Fall Seminar Series
OCR
October 15, 2014 35 2014 California Space Grant Fall Seminar Series
Image Processing
October 15, 2014 36 2014 California Space Grant Fall Seminar Series
2013 Team
October 15, 2014 37 2014 California Space Grant Fall Seminar Series
Lessons Learned
October 15, 2014 38 2014 California Space Grant Fall Seminar Series
• Teamwork • Initiative • Diversity • Most noticed point on resume in job fairs! • Experience has helped with my research
October 15, 2014 2014 California Space Grant Fall Seminar Series 39
Sterna Introduction
• Sterna is a UAS designed and built in the CASL
• Sterna v3 currently under design/fabrication
• All composite plane with multiple wing sets
• Used for research of in-flight SHM
October 15, 2014 2014 California Space Grant Fall Seminar Series 40
Sterna Fabrication Progress
• Testing fuselage curing complete, ready for bonding
• Used to validate design
October 15, 2014 2014 California Space Grant Fall Seminar Series 41
Overview
• Introduction
• CASL Undergraduate Research Assistant
• Nano-Reinforced Polymer Composites
• Composite UAV Design and Fabrication
• Active Load Redistribution
• Structural Health Monitoring and Prognosis
• Opportunity Available
• Tips for Success
• Conclusions
Introduction
2014 California Space Grant Fall Seminar Series
Project Objectives • Build small UAS platform to allow for
experimentation in active control of segmented control surface (SCS) wings
• Utilize compact fiber optic strain sensing (cFOSS) system to measure in-flight structural response
• Develop models to predict aerodynamic loading and structural response
• Control in-flight wing deformations using real-time cFOSS data
2014 California Space Grant Fall Seminar Series
Segmented Control Surfaces
• Current wing control surface configurations often produce unnecessary structural and aerodynamic loads
Flap
Aileron
2014 California Space Grant Fall Seminar Series
• Current wing control surface configurations often produce unnecessary structural and aerodynamic loads
• SCS allow for higher resolution of aircraft control input
• SCS can be optimized over the flight envelope
• Key step to implementation of conformal control surfaces/ flexible wing concepts
cFOSS System • cFOSS system utilizes glass
optical fibers as strain sensors • Fiber Bragg gratings (FBG)
distributed along fiber • Laser interrogates fibers with
incident light • Straining fiber modifies FBG
spacing and hence reflected wavelength
• Capable of ~4000 strain measurements at ~50Hz
2014 California Space Grant Fall Seminar Series
Aircraft (APV-3)
• Span: 12.33 ft • Dihedral: 2.5 ̊ along hinge line • Structure: Monocoque composite • Original control surfaces: Flap and aileron on each wing, split elevator, rudder
• Weight (without cFOSS system): ~35lbs • Weight (with cFOSS system): ~45lbs • Max gross takeoff weight: 55lbs • Fully autonomous capabilities (Piccolo II)
2014 California Space Grant Fall Seminar Series
Fiber Optic Strain Sensors
• Continuous grated fiber with strain data measured every 0.5”
• 86ft of fiber provides over 2000 real-time strain measurements
• Fiber rosettes allow for shape, displacement, twist and principle strain calculations
Fiber Optic Strain Sensors
2014 California Space Grant Fall Seminar Series
Segmented Control Surfaces
• Wings modified to include 22 independent control surface segments/servos per wing
• Servo uniformly spaced to produce 3” SCS from existing control surfaces
2014 California Space Grant Fall Seminar Series
Complete System
2014 California Space Grant Fall Seminar Series
Aerodynamic Analysis • Utilized Athena Vortex
Lattice (AVL) and XFLR5 programs
• Analytical model prepared for predicting aerodynamic loading of conventional and SCS configurations
• Aides in optimization of SCS configuration at various flight conditions
2014 California Space Grant Fall Seminar Series
Structural Analysis
• Developed 32,000 element single wing model in FEMAP
• Wing loaded along quarter chord with load distributions predicted by AVL (40 nodes along span)
• Model solved with NX Nastran yielding strain and displacement predictions
• Used to study effects of SCS configuration on displacement and strain
Conventional Control Surface
Segmented Control Surface
2014 California Space Grant Fall Seminar Series
Complete Systems Test
2014 California Space Grant Fall Seminar Series
Complete Systems Test Video
2014 California Space Grant Fall Seminar Series
Test Flights • Test flights conducted at
Dryden Flight Research Center small UAS work area
• Same Flight Patterns flown with (mimicked) conventional and segmented control surface configurations
• Circuits Flown – Steady Level Flight – Pitch Doublets – Roll Doublets – High g Steady Turn
2014 California Space Grant Fall Seminar Series
Flight Results-Time History
Filtered Acceleration
vs. Time
Filtered Wing Tip Deflection
vs. Time
2014 California Space Grant Fall Seminar Series
Flight Results-Time History
Filtered Acceleration and Wing Tip Deflection vs.
Time
Normalized Wing Tip
Deflection vs. Time
Control System On Control System Off
2014 California Space Grant Fall Seminar Series
Flight Results-Conventional
2014 California Space Grant Fall Seminar Series
Lessons Learned
• Self motivation • Team work • Building relationships
2014 California Space Grant Fall Seminar Series
October 15, 2014 2014 California Space Grant Fall Seminar Series 59
Overview
• Introduction
• CASL Undergraduate Research Assistant
• Nano-Reinforced Polymer Composites
• Composite UAV Design and Fabrication
• Active Load Redistribution
• Structural Health Monitoring and Prognosis
• Opportunity Available
• Tips for Success
• Conclusions
Introduction- Motivation
• Inability to monitor damaged initiation and progression limits expanded use of composite
• Ability to detect and quantify
damage will be key to widespread acceptance of composite flight structures
2014 California Space Grant Fall Seminar Series October 15, 2014 60
Introduction- SHM
2014 California Space Grant Fall Seminar Series October 15, 2014 61
• Integrate an advanced sensor network to determine the structures current health and predict the future/remaining life
• Current CASL research
focuses on main wings
Defining Damage
2014 California Space Grant Fall Seminar Series October 15, 2014 62
Defining Damage
• Composites suffer from impact, overload and fatigue damage
• Failure by strength exceedance or stiffness degradation (flutter)
• The proposed system aims to detect:
• Fiber failure • Delamination • Matrix cracking • Bond strength
Operational and Environmental Variability
• Operational Variations include:
• Flight Velocity • Altitude • Maneuvering (V-n) • Loads • Changes in mass
• Environmental
Variations include: • Winds • Turbulence • Temperature
0 50 100 150 200 250 300-4
-3
-2
-1
0
1
2
3
4
5
6V-n and Gust Diagrams
Velocity, [ft/sec]Lo
ad F
acto
r (n)
Flaps UpFlaps DownGust
Lift = nW = 1/2ρV2SCL
October 15, 2014 2014 California Space Grant Fall Seminar Series 63
Sensor System
• Extensive use of optical fiber strain sensors
• Supplement with a few
targeted traditional piezoceramics accelerometers
• High frequency modal measurements
• Secondary system to measure airspeed, gust loading, altitude, density and temperature
2014 California Space Grant Fall Seminar Series October 15, 2014 64
Modal Based Features
• Estimate modal parameters (natural frequencies, damping) to detect presence of damage
• Estimate mode shapes to detect damage location
• Mode shape derivatives (Curvature)
• Need accelerometers for higher modes
• Damage localization • Relies heavily on physical model
updating • Assumes linear behavior
• Nonlinearities can infer damage
Damage
2014 California Space Grant Fall Seminar Series October 15, 2014 65
Physics Based Modeling
• Need to develop vast database of structural models to develop relevant statistical models
• Strain and modal based method rely heavily on structural models • Use database to train SHM statistical algorithms
1st Bending Mode ∼7.5Hz
2014 California Space Grant Fall Seminar Series October 15, 2014 66
Supervised Machine Learning
• Building multiple wing sets allows for data to be collected from damaged and undamaged wing sets
• Heavily damaged wings cannot be flown so must be tested using static and dynamic ground test
• Supervised learning allows for damage detection, sizing, type and possibility of prognosis
2014 California Space Grant Fall Seminar Series October 15, 2014 67
On Going Work in SHM
• Current efforts in the CASL focus on composite beam testing
October 15, 2014 2014 California Space Grant Fall Seminar Series 68
DWDM Sensor
FBGS Sensors
On Going Work in SHM- Test Setup
• Fiber optic strain gages bonded to beam
• Currently ~1200 gages • Strain information
recorded for static and dynamic loads
October 15, 2014 2014 California Space Grant Fall Seminar Series 69
On Going Work in SHM- FEM
• Beam modeled in FEMAP • Information pulled from nodes
corresponding to strain gages locations on physical beam
October 15, 2014 2014 California Space Grant Fall Seminar Series 70
Simulated Impact
• Simulate impact by reducing stiffness of elements by 10% in 0.25” radius
October 15, 2014 2014 California Space Grant Fall Seminar Series 71
Simulated Fiber Breakage
• Simulate fiber breakage by deleting one 0.088”x0.088” element
October 15, 2014 2014 California Space Grant Fall Seminar Series 72
Lessons Learned
Patience
October 15, 2014 2014 California Space Grant Fall Seminar Series 73
October 15, 2014 2014 California Space Grant Fall Seminar Series 74
Overview
• Introduction
• CASL Undergraduate Research Assistant
• Nano-Reinforced Polymer Composites
• Composite UAV Design and Fabrication
• Active Load Redistribution
• Structural Health Monitoring and Prognosis
• Opportunity Available
• Tips for Success
October 15, 2014 2014 California Space Grant Fall Seminar Series 75
Student Orgs
• Engineering Organizations with Project Teams at UCSD:
http://www.jacobsschool.ucsd.edu/student/student_involved/involved_org/
October 15, 2014 2014 California Space Grant Fall Seminar Series 76
Internships
• Port Triton
• DECaF Job Fair
• Student Services Center • Go to resume/interview workshops
• Employer Website
• NASA OSSI - https://intern.nasa.gov/ossi/web/public/main/
• One stop for Internships, fellowships and scholarships with NASA
October 15, 2014 2014 California Space Grant Fall Seminar Series 77
Research Labs
• Most professors on campus conduct research • If you’re interested in a class, do well, make yourself known to the
professor and then ask about the research they do
• Some opportunities are even paid!
October 15, 2014 2014 California Space Grant Fall Seminar Series 78
Overview
• Introduction
• CASL Undergraduate Research Assistant
• Nano-Reinforced Polymer Composites
• Composite UAV Design and Fabrication
• Active Load Redistribution
• Structural Health Monitoring and Prognosis
• Opportunity Available
• Tips for Success
October 15, 2014 2014 California Space Grant Fall Seminar Series 79
Tips for Success
• Remember all opportunities are good opportunities • Doing something slightly interesting may lead to very interesting things
in the future
• Stay patient
• Show initiative
• Work hard/ Always do your best
• “You don’t know what you don’t know”
80
Acknowledgments
October 15, 2014
I would like to thank my mentors, - Dr. John Kosmatka, University of California, San Diego - Dr. Lance Richards, NASA AFRC/AERO Institute - Francisco Pena, NASA AFRC/AERO Institute And, Tehseen Lazzouni and Rebecca Howard from the California Space Grant Consortium As well as numerous people at NASA Armstrong who provided advice, guidance and support, including:
- Robert “Red” Jensen - Allen Parker - Dr. Oscar Murillo - Dr. Patrick Chan
2014 California Space Grant Fall Seminar Series
81
Support
October 15, 2014
Funding for these project was provided by: - NASA Aeronautics Research Mission Directorate - NASA Aeronautics Academy, Dryden Flight Research Center - California Space Grant Consortium
2014 California Space Grant Fall Seminar Series
82
Questions ?
2014 California Space Grant Fall Seminar Series October 15, 2014