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Carbon Fiber Push Rods Research Proposal
Composite-Dynamics Meeting 10/5/2024
Composite Dynamics Stuff Initial Testing Plan
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Tube Rock West Carbon Fiber Push Rod Stock
Inserts interfaced with Carbon Fiber Tube
Things to test
Mechanical Tests
Tensile Test- needed for plug
How to test it
Probably not needed since the push rod will be under constant compression
Flexural Test
three-point and four-point bend testing according to ISO 14,125, ISO 178, ASTM D 790, and ASTM D 6272
parameters for this test are the support span, the speed of the loading, and the maximum deflection for the test
Impact Test
Compression Test
End loading
Sheer loading
ASTM D 695, ASTM D 3410, and ISO 14,126.
information on elastic limit, proportional limit, yield point, yield strength, and compressive strength
Strength at high temperatures (Summer)
Fatigue Failure?
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Insert Testing
Adhesive
strength tapers off pretty fast around 40 degree celsius
Lap shear strength: 3740 psi, 26 N/mm^2
DP420
Etched Aluminum Strength Test: 4500 psi
Couldn’t find temp to % strength chart
DP460
FPL Etched Aluminium Shear Strength: 31 N/mm2 OR 4500 psi
Couldn’t find temp to % strength chart
Loctite - Hysol E‐120HP
room temp cure
Tensile strength of 41 N/mm^2
Aluminum abrasion and acid etched lap shear strength 33 N/mm^2 (4800 psi)
100% strength even at 40 degrees Celsius
Tube and metal prep
Aluminum etching and Alodine coating to prevent corrosion and increase bond strength
West System 860 Aluminum Etching Kit
DuPont Acid Etch and Alodine solutions
Submerge Aluminum in etch solution, then submerge in non-diluted Alodine solution
Aluminum stock for insert
Check for appropriate lengths
Bond length increases linearly with bond strength
Gap 0.004 - 0.012 in for hot bonding
Gap 0.008 in for cold bonding
Carved aluminum, tapped for fitting a bearing insert
create shoulder only for grabbing in tensile test
In MIT paper, flashbreaker tape was used to add thickness at the end of the insert to create equal spacing and center insert.
Materials
x1 45552 (Depends on Dynamics decision for rod end size) CF Tube (60in)
Produces x12Helicoil
Could avoid use if we use steel stock for the inserts
If we use a 1/4” - 28 End Rod
the bore hole will have to be #3 drill bit (0.213 inches)
tapped using 1/4" - 28 STI tap
Insert a 1/4" - 28 bolt Helicoil
Adhesive strength
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$$\tau \cdot A= F_{max}$$ |
Lap Shear Strength x Surfaces Area = Max Force
To determine the length of our insert:
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$$L_{ength} = \frac{F_{max}}{\pi d \tau}$$ |
Assuming we need a max Force of [sum] newtons and a diameter of 0.25 inches, Our minimum length is [something] millimeters
The 0.25 in rod end is already an inch long so the minimum depth of inert is 1 inch.
Materials
x1 46610-DL
Can produce 14 5-in test tubes
Aluminum Rod (for milling our own insert, alloy and site unknown)
Some kind of acid etch kit (not necessary but good for testing bond strength variable)Obsolete and not able to purchase kits anymore
Process for Insert Tensile Test
Create Aluminum inserts
0.004-0.012 in gap
Leave shoulder length for Instron machine to grab
Have a length of about [some] inches that will adhere to the inside of tube
Cut the Carbon Fiber tubes into about 3-5 inch sections
The tubes are 5 feet long, so we can get at least 12 tests from one tube
Prep the surfaces
The aluminum inserts will be sanded, degreased, submerged in etch solution for 3 minutes, then submerged in non-diluted Alodine solution
The CF inner part will just be sanded and degreased
Add Epoxy
We may test mixing the epoxy with small glass beads to properly center the insert, or use of Flashbreaker tape
Slather chosen epoxy on the insert and inner part of CF tube
Insertion
Slowly push insert into tube and let cure for 24 hours.
Testing
After putting the insert into both sides of the tube, attach to Instron machine
Pull until failure
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