ENSC 22 FIRE RESISTANT SURFACES & SPOILER DESIGN

Team: Chrystal Camacho, Andrew Justice, Matt Knowles, Mike Phillips

Advisor: Andrew Johnston

BACKGROUND • Phase 1: Enhanced Fire Protection For Metal-Bonded Surfaces

Baseline skin to the rear of the nacelle is aluminum, with an E-glass skin.

Per FAR 25.867: Skin w/in 2 nacelle diameters to the rear of the nacelle must withstand 2000 degree Fahrenheit flame burn test for 5 minutes at a distance of 4 inches from the burner exhaust.

We must find a suitable replacement for the baseline skin that can pass the Federal Aviation Regulation (FAR) 25.867 test

• Phase 2: Design Optimization of Spoilers

We must analyze different materials and manufacturing methods

Goal: reduce weight and cost

Current process: metal-bonded assemblies

PHASE 1

PHASE 1 BACKGROUND FAR FAR 25.867 states:

Ҥ 25.867 Fire protection: other components.

( a) Surfaces to the rear of the nacelles, within one nacelle diameter of the nacelle centerline, must be at least fire-resistant.

(b) Paragraph (a) of this section does not apply to tail surfaces to the rear of the nacelles that could not be readily affected by heat, flames, or sparks coming from a designated fire zone or engine compartment of any nacelle.”

PHASE 1 RESEARCH HISTORY INVALID SOLUTIONS

• PyroSic / PyroKarb by Pyromeral Systems

• K-Shield Felt by Hexcel Corp.

• Nextel 312 Ceramic Fiber Fabric by 3M

• Ceramic Spray Coating by Jet-Hot

SOLUTION: SANDWICH PANEL

3 Plies of S2 Style 6781 Fiberglass w/ RM-3004 BMI Prepreg

1 Ply of RM-3011 BMI Film Adhesive

Front Aluminum Face Plate

Aluminum

Honeycomb Core

Back Aluminum Face Plate

SOLUTION: S-2 FIBERGLASS STYLE 6781 • Softening Temperature is 1933°F

• High strength capacity

• Density = 0.0889 lb/in3

• Renegade Materials is a vendor

Company performs custom work

• Similar to Boeing’s current fiberglass solution to FAR 25.867

Implementation of manufacturing

change would be small

Renegade Materials HQ in Miamisburg, OH

SOLUTION: BMI Prepreg • Renegade Material’s RM-3004 BMI Pre-Impregnation( Prepreg)

Out of Autoclave (OOA ) Process

• Glass Transition Temp = 530°F w/ Post Cure, 484°F w/out Post Cure

Higher temp rating than epoxy currently in use

• Has been proven to pass the FAR 2000°F burn test

Test conducted by University of Cincinnati in conjunction w/ Renegade and GE

BMI used on carbon fiber panel

SOLUTION: MANUFACTURING

• Janicki Industries

Students perform manufacturing of panel

Impregnate S2-Style 6781 Fiberglass with

RM-3004 BMI Prepreg

Cure by Out of Autoclave

(OOA) process

Post-Manufactured skin thickness of

0.024± 0.005-in (total thickness of all 3 plies

+ adhesive film )

will be close to that used by Boeing (0.02 in)

REMOVING ORIGINAL E-GLASS FROM SUPPLIED COUPONS

• Original fiberglass skin had to be removed in order to be replaced

• Methods:

Paint stripper

Hydrochloric acid

Sulfuric acid

Nitric Acid

Milling

Filing

Sand blasting

Electric sanding

Ineffective

Effective, but not

time efficient

Best method

Effective & time

efficient

Scratches

from filing

Sand blasted

area

ALODINING THE COUPONS Before Alodining

After Alodining

During Alodining

CUTTING THE BMI PREPREGED FIBERGLASS & FILM ADHESIVE

RM-3011 BMI film adhesive applied using freeze spray

S2 fiberglass pre-impregnated with RM-3004 BMI

LAY-UP PROCESS

OVEN CURE PROCESS

Renegade Materials

Recommended cure

Janicki Industries

Recommended cure

ENSC 22

Performed cure

16 hours – Room

Temperature Debulk

8 hours – Room

Temperature Debulk

8 hours

2 hours @ 260 ⁰F 9 hours 2 hours

2 hours @ 290 ⁰F 2 hours 2 hours

6 hours @ 375 ⁰F 6 hours 6 hours

Post Cure – 6 hours

@ 475 ⁰F

6 hours N/A

Recommended Cure steps VS. Actual Cure steps performed by ENSC 22

Panels after the

envelope and curing

supplies were

removed

POST-MANUFACTURING The condition of the

panels shipped to

GU (from Janicki)

TESTING PROCEDURE 1) Place thermocouples on

front and back of coupon

2) Connect thermocouples to

LabVIEW

3) Position and center test face of

coupon 4-inches away from burner

exhaust

4) Calibrate burner using Fluke

meter thermocouple. Keep

burner cover on

5)Upon completion of calibration,

remove burner cover to expose

coupon to flame

6) Start timer and begin running

LabVIEW continuously

7) Let test run for at least 5

minutes. Use Fluke meter

thermocouple to ensure flame

temp is at least 2000°F

8) After test has run for at least 5

minutes, turn off burner to end

test. Stop running the LabVIEW

VI

9) Record all observations via

pictures, descriptions, and/or

videos. Extract LabVIEW data

10) Repeat steps 1-9 for all

remaining coupons

NOTE: In event of test

failure of coupon, turn

off burner to end test

immediately.

• (x4) OMEGA ® Nextel Ceramic Insulated Type K Thermocouples, 14 gage

(XC-14-K-12) for front face of coupons:

• (x4) OMEGA ® Precision Fine Bare Wire Type K Thermocouples, 0.010-inch diameter (CHAL-010) for back face of coupons:

• 1-inch thick ceramic fiber kaowool fire blanket for burner cone, burner cover, and coupon insulation:

• Phenolic board to support back side thermocouples:

• Ceramic bricks to support burner cone and coupons:

TESTING MAIN EQUIPMENT

DEVIATIONS FROM FAR IN TESTING

• The coupons are not 12”X12” plates – vary in size, depth, and surface profile .

• Burner used in the test was an oxy-acetylene torch airflow and heat flux varied from the FAR requirement.

Could still reach and maintain temperature of 2000ºF.

• Burner was made out of 1-inch thick kaowool and steel wire ties rather than inconel

• Test stand used ceramic blocks to prop up coupons and burner. The burner was also made stationary by use of a sheet metal base.

• A phenolic board was used behind coupons to support thermocouples on back side.

• Kaowool was used on edges of coupons in last 3 tests as insulation to prevent burn-around.

TESTING SETUP

4 bare-wired, lower

temp thermocouples

5-8 protruding

through phenolic

board, touching back

of coupon

Phenolic

board

Ceramic bricks

Fluke meter

thermocouple

Coupon

Burner cover for

calibration

Burner cone

Kaowool insulation

• Thermocouples were connected to a

DAQ which relayed data to LabVIEW

4 insulated, high temp

thermocouples 1-4 draped

over coupon

TESTING CALIBRATION

• Fluke meter was used to

calibrate burner

• Burner cover with kaowool

shield was placed over

burner

• Prevented panels from

burning during

calibration

• Burner cover was lifted to

begin test

TESTING

Coupon 1 Coupon 2

Coupon 3

DATA

Coupon 1 Coupon 2

Coupon 3

NOTE: “Temp. 2”

thermocouple, which

exceeded 2000°F, burned

off during Coupon 3 test

• Video evidence of Fluke-meter

thermocouple exceeding 2000°F

exists, to support conclusions

UNIVERSITY OF CINCINNATI RENEGADE MATERIAL TEST

TESTING RESULTS

Coupon 1 Coupon 3 Coupon 2

PHASE 1 CONCLUSIONS

Coupon w/ S2 fiberglass

prepreged w/ RM-3004 BMI skin The coupons with S2 fiberglass prepreged w/ RM-

3004 BMI as a protective skin PASSED the FAR

25.867 test by exhibiting no burn-through when

subjected to a 2000ºF flame for 5 minutes.

In conclusion, the S2 fiberglass prepreged w/ RM-3004

BMI skin is:

• A VIABLE SOLUTION for Boeing to use on its aircrafts

to pass the FAR 25.867.

• EASILY IMPLEMENTABLE, as the manufacturing/layup

process is very similar to that of the fiberglass prepreg skin

that Boeing currently uses.

Also note that S2-glass has a lighter density more heat

resistive than E-glass:

• S2-glass density = 0.0889 lb/in3 Softening Temp. = 1932°F

• E-glass density = 0.0932 lb/in3 Softening Temp. = 1554°F

The RM-3004 BMI prepreg resin density is 0.0452 lb/in3.

The resin content in our prepreg was 38 ± 3%

BUDGET ***Does not include ~$850 RM Shipping Cost/Trip to Boeing***

Original projected budget = $4800

PHASE 2

• Initial goal was to find solution that was more lightweight and/or inexpensive than current solution

• Needed to meet TDS

1. Build Requirements

2. Stress Requirements

3. Environmental Requirements

4. Cost Requirements

PHASE 2 BACKGROUND

HM Hinge Moment

HL Hinge Line

dx Distance from spoiler hinge line to LE of spoiler

Csp Spoiler Chord Length

P Pressure

Ssp Spoiler Aerodynamic Area

PHASE 2 RESEARCH HISTORY POTENTIAL SOLUTIONS • Polyurethane Foams

• Carbon Fiber Panels

• Metal Foams

• Aluminum Honeycomb

PHASE 2 RESEARCH HISTORY POLYURETHANE FOAMS General Plastics Manufacturing Company makes aerospace-grade rigid polyurethane foams (FR-6700 rigid foam series)

Advantages

1. Claims to be flame retardant, highly resistive to water absorption, inert to chemicals, and possess high strength-to-weight ratio

2. FR-6710 is lightest in the series, with density of 10 lb/ft3 and properties as seen in table

3. Could use to replace certain sections of honeycomb core

Disadvantages

1. Would make honeycomb manufacturing more difficult and expensive

2. Implementation change required would be drastic and costly

FR-6710 (Density = 10 lb/ft3)

Property

English Metric

Tensile Strength (psi) (kPa)

Parallel to Rise 303 2088

Perpendicular to Rise 307 2114

Shear Strength (psi) (kPa)

Rise Parallel to Specimen Width 239 1650

Rise Parallel to Specimen Thickness 254 1751

Shear Modulus (psi) (kPa)

Rise Parallel to Specimen Width 2823 19465

Rise Parallel to Specimen Thickness 3195 22032

Flexural Strength (psi) (kPa)

Rise Parallel to Test Span 480 3308

Rise Parallel to Beam Thickness 406 2800

Flexural Modulus (psi) (kPa)

Rise Parallel to Test Span 14017 96645

Rise Parallel to Beam Thickness 11449 78938

Water Absorption (lb/ft2) (kg/m2)

0.049 0.238

PHASE 2 RESEARCH HISTORY CARBON FIBER PANELS

• Carbon fiber panels cannot be directing bonded to the spoiler’s aluminum skins due to Galvanic Corrosion.

• Carbon fiber is still an expense product that can not rival the inexpensive of aluminum honeycomb panels.

• Carbon fiber bonded assemblies would increase manufacturing costs of the spoiler.

PHASE 2 RESEARCH HISTORY METAL FOAMS

• Fairly new technology

• Applications: sound absorbers & thermal

insulation

• Advantages: lower density, cost

• Manufacturing:

• Compact-powder foaming

• 5 stages: making the precursor, initial pore

formation, pore inflation, foam

degradation, and solidification

• Disadvantage:

• Monitoring metal foam formation

• Physical properties

PHASE 2 RESEARCH HISTORY ALUMINUM HONEYCOMB

• HexWeb® Aluminum Flex-Core Commercially available aluminum

honeycomb core specifically designed for formability

Retains mechanical properties in sharp curvatures

Offers cost savings for curved panels

CHARACTERISTICS UNITS

Current

Solution

5056/F80 -

6.5

Aluminum

Flex Core

Compression Strength psi 810 1500

Compression Modulus psi 227520 310000

Longitudinal Shear Strength psi 486 645

Longitudinal Shear Modulus psi 100080 73000

Transverse Shear Strength psi 297 420

Transverse Shear Modulus psi 47970 24000

Density lb/ft^3 6.9 6.5

• Advantages:

Light Weight

Low Cost

High Strength

• Disadvantages Potential corrosion in salt-water

Contact with carbon skins may cause galvanic corrosion

PHASE 2 ACTION PLAN ANSYS Simulation

• Separate SolidWorks spoiler model into its solid body constituents.

• Using the appropriate material properties located in the decision matrix, designate a material for each solid body. (Core properties, facing skin properties, material characteristics of spar elements, etc.)

• Convert individual SolidWorks part files into ANSYS part files.

• Reassemble the spoiler in ANSYS.

• Simulate the loading conditions provided and analyze results.

PHASE 2 ACTION PLAN Business Case

• Brief summary of alternative designs that were explored.

• Compare performance of current design and proposed solution.

• Include cost analysis detailing how the proposed solution is more cost efficient in regards to raw material cost, money saved with weight reduction, and manufacturing expenses.

• Goal: The proposed solution will meet the load requirements while reducing the weight and cost of the spoiler.

• Prediction: An alternative aluminum honeycomb with a lower density and lower cost is the best option for improving upon the current design while still meeting the load requirements.

• Rationale: The high strength/weight ratio of aluminum honeycomb is currently unrivaled by other core materials such as composites and foams.