Anyone ever tried *solid* carbon fiber plate for fins?

The Rocketry Forum

Help Support The Rocketry Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

RGClark

Mathematician
Joined
Aug 25, 2017
Messages
315
Reaction score
31
Location
Philadelphia, PA USA
In looking at examples of "carbon fiber" fins I've only seen cases actually consisting of fiberglass plate, commonly G10, with layers of carbon fiber fabric laid on top to serve as reinforcement. See for example here:

https://groveraerospace.com/?page_id=79

But solid carbon fiber is legendary for its stiffness. For instance in Formula 1 car racing, where saving weight is nearly as important as for space rockets, the chassis and roll cage are now exclusively made of carbon fiber because of its resistance to bending and twisting at lightweight.

Then solid carbon fiber plate can provide the same resistance to bending as with fin flutter as aluminum but at a smaller thickness for the fins:

https://www.dexcraft.com/articles/c...als/#rigidity_and_strength_the_same_thickness

For the sizes needed for fins it is not particularly expensive either:

1-8-solid-cf-sml.jpg

https://dragonplate.com/ecart/categories.asp?cID=65

Carbon Fiber Sheet 1.5mm*300mm*150mm.
https://hobbyking.com/en_us/carbon-fiber-sheet-1-5mm-300mm-150mm.html


Bob Clark
 
I have two solid carbon plate MD rockets. One is a 38mm MD the other a 54mm MD, both were all CF kits and I did a single 3K 2x2 twill CF layup on both under vacuum. I also have a laminated G10 core T2T under vacuum for a G12 kit, which is a 38mm MD as well as a 3" cardboard with ply core fins that has a single CF layer just laminated on the fins but no vacuum layup.

With all of these rockets one could argue the process is not required for the stresses they may experience, but they are required to push my knowledge on composite layups and hands on techniques forward. I am currently building a 54mm sub-MD using Dragon plate and have a 98MM sub-MD on the drawing board that will also use Dragon plate and that I will finalize the plans for once I get some feedback on the 54mm sub-MD assembly and performance.
 
The TARC team I mentor used solid carbon fins, about 1/16" thick. The didn't really save weight over 1/8" plywood, but the reduced cross section netted about 75 feet difference in altitude.
 
I have various fins in uni-directional carbon, carbon weave and the original carbon matrix - wood.
 
The TARC team I mentor used solid carbon fins, about 1/16" thick. The didn't really save weight over 1/8" plywood, but the reduced cross section netted about 75 feet difference in altitude.

Thanks for the response. I'm really interested in the case for high power rockets, to reach supersonic speeds. In that case the thin fins result in a large change in altitude.

Bob Clark
 
Thanks for the response. I'm really interested in the case for high power rockets, to reach supersonic speeds. In that case the thin fins result in a large change in altitude.

Bob Clark

The challenge there is that the fin stiffness varies by either the cube or the square of the fin thickness. Along with that, the core of the fin doesn't contribute all that much to the stiffness--you just need a good shear connection to hold the outside plies apart. The operating theory behind using G10 cores with CF T2T is that the G10 core is pretty cheap and readily available and does what you need it to do, and you can save your carbon budget for the outer plies where it does more good. Along the same line, there's another thread out now about using a honeycomb core on one of the Der Red Max upscales to save weight.

TL;DR: You can probably make the fins a little thinner using solid CF plate vs. G10 with an overlay, but probably not as much thinner as you'd assume just looking at the material properties.
 
The thin fin will always have less frontal cross sectional area which by fluid mechanics will have less drag force. Yes my group has flown rockets to M1.6 on CF plate 1/16" this year. Last year was only to M1.1 on only CF plate. This was for 29mm MD rockets on H and I class L-1 motors. Bigger body tube diameters like 54mm generally use 3/32" and thicker as tube size increases. The span, thickness, and Mach number are going to determine when the fin literally rips off in flight by flutter. Some of the Wildman and Madcow kits include CF plate fins. BH29 had 1/16 CF fins.

That Jarvis guy has pushed fins to M2.5. And has his build input techniques here for CF.
https://www.raketenmodellbau.org/repository/archive/167792?view=true

https://www.raketenmodellbau.org/repository/archive/167793?view=true

I posted those because when new it's hard to understand all the tip to tip methods until someone shows you the process.
 
The thin fin will always have less frontal cross sectional area which by fluid mechanics will have less drag force. Yes my group has flown rockets to M1.6 on CF plate 1/16" this year. Last year was only to M1.1 on only CF plate. This was for 29mm MD rockets on H and I class L-1 motors. Bigger body tube diameters like 54mm generally use 3/32" and thicker as tube size increases. The span, thickness, and Mach number are going to determine when the fin literally rips off in flight by flutter. Some of the Wildman and Madcow kits include CF plate fins. BH29 had 1/16 CF fins.

That Jarvis guy has pushed fins to M2.5. And has his build input techniques here for CF.
https://www.raketenmodellbau.org/repository/archive/167792?view=true

https://www.raketenmodellbau.org/repository/archive/167793?view=true

I posted those because when new it's hard to understand all the tip to tip methods until someone shows you the process.

I saw you have access to a wind tunnel. Perhaps you can do wind tunnel tests on using thin carbon fiber plate of various types and thicknesses at the high Mach speeds needed to get to the von Karman line, say to Mach 6 and above. An OpenRocket sim (attached) on a N5800-to-N5800 rocket showed an increase in altitude of 77,000 meters in changing the fin thickness from 1/4" to 1/16".

Keep in mind there are variations in strength of the carbon fiber plate depending of the orientation of the fibers. See for example here:

================================================================================
Aluminium vs carbon fiber – comparison of materials.

1. Stiffness and strength of material in relation to weight
Weight for weight, carbon fiber offers 2 to 5 times more rigidity (depending on the fiber used) than aluminium and steel. In the case of specific components that will be stressed only along one plane, made from one-direction carbon fiber, its stiffness will be 5-10 times more than steel or aluminium (of the same weight).
The following tables compare stiffness and resistance to damage for different materials of the same weight. For the purpose of analysis, two-direction carbon fiber was applied – one most often used for manufacture of composites, and one –direction carbon fiber – used occasionally, mostly for products where stress is expected only along one plane.
Analysis of aluminium, steel and two-direction carbon fiber regarding stiffness against weight and strength against weight:
AluminiumSteelTwo-direction carbon fiber – common modulusTwo-direction carbon fiber – improved modulusTwo-direction carbon fiber – highest modulus
Stiffness against weight(Specific Modulus)
Unit: 10 6 m2s-2
26255683120
Resistance to damage(Specific Strength)
Unit kN·m/kg
214254392211126

Analysis of aluminium, steel and one -direction carbon fibre regarding stiffness against weight and strength against weight:
AluminiumSteelOne -direction carbon fiber – common modulusOne -direction carbon fiber – improved modulusOne -direction carbon fiber – highest modulus
Stiffness against weight(Specific Modulus)
Unit: 10 6 m2s-2
2625113166240
Resistance to damages(Specific Strength)
Unit kN·m/kg
214254785423252
The above data for carbon fiber sheets relates to a sample made using the technology of epoxy resin infusion (70/30% ratio of carbon fiber to resin).
The above statement shows many advantages provided by carbon fiber, as well as elements designed and made from carbon fiber. Fabrics of improved and highest modulus relate to special materials (unfortunately very costly) that offer rigidity characteristics x 2 times more than standard carbon fiber, and they are used mostly in military applications and the aerospace industry.
To interpret the results shown in the table, imagine that a design engineer is going to construct a strong and lightweight carbon fiber sheet of 1m2 with maximum weight of 10 kg and he considers aluminium, steel and carbon fiber.
Remembering the weight limit of 10 kg, the design engineer may choose:

  • Steel slab about 1.5 mm thick.
  • Aluminium slab about 4 mm thick.
  • Carbon fiber slab about 7 mm thick.
Carbon fiber provides 2 essential benefits.
Carbon fiber offers more stiffness (as described above) at lower density and consequently the product of the same weight may be thicker, that will result in stiffness improved by increased thickness alone. To put it simply, material thickness increased x 2 provides rigidity of 23 – so about 8 times more. This provides many opportunities with regard to weight reduction thanks to the use of carbon fiber.
================================================================================
https://www.dexcraft.com/articles/c...nium-vs-carbon-fiber-comparison-of-materials/


So for one type of carbon fiber the increase in stiffness over aluminum is nearly by a factor of 10, as long as the stress is in one plane.

Bob Clark

View attachment N5800 to N5800- 3 fin.ork
 
I saw you have access to a wind tunnel. Perhaps you can do wind tunnel tests on using thin carbon fiber plate of various types and thicknesses at the high Mach speeds needed to get to the von Karman line, say to Mach 6 and above. An OpenRocket sim (attached) on a N5800-to-N5800 rocket showed an increase in altitude of 77,000 meters in changing the fin thickness from 1/4" to 1/16".

You won't be doing mach 6 with 1/16" thick fins. Even if they didn't flutter to pieces, they would ablate to nothing.
 
Not to mention that m6 tunnels aren't exactly commonplace.

That's OK. I'll bet a 6-pack* that 1/16" fins carbon plate fins large enough to stabilize a suborbital rocket will flutter and peel off by M1.5. That wind tunnel is a lot easier to find.

* Must provide video evidence. Offer valid for pickup in Seattle. Void where prohibited.
 
In theory (or on paper) we can accomplish almost anything!

:D

We can do things so easy in the virtual world. Cracks me up how some people come into the hobby with these "new" ideas like they are the very first to think of them. Reality is hard, some people need to get out there and try it sometime. I manufacture fin cans proven to mach 5+ and if there were an easier (or better) way, I'd already be doing it.
 
University of Tennessee Chattanooga's wind tunnel is limited to Mach 1. The maximum useful Mach number was derated to Mach 0.8 because the brilliant designer didn't put the drain hole on the bottom so over the years moisture has rusted the pressure vessel internally. Hey engineers are humans too! The testing area is limited to 1" x 1" x 1" objects for actual tests. The CFD virtual wind tunnels are math models by Dr. Sreenivas a hypersonics flow expert at the Sim Center which virtually go to M25. But you'd need a CAD 3D file meshed. There's a low speed wind tunnel in fluid mech lab that goes to 60mph for larger models 5" x 5" x 12"?

UTSI has a Mach 4 wind tunnel. They are well equipped for advanced research. UTC doesn't have an aeronautical/aerospace program but a few professors have aerospace PhD with some experience in industry.

NAS Tullahoma has AEDC a civilian contractor company for hypersonic M5+ wind tunnel ops. Large scale multi million dollars. You can enter a test matrix with the United States Air Force. I was lucky to meet a director in person for a career day and I asked of how companies got access to national hypersonic wind tunnels, apparently a formal test matrix is required. Nobody else cared. I get curious about that kind of thing. Think Lockheed Martin, Boeing, and on a military project Etc. They have tested semi trucks for trucking companies on low speeds larger cheaper subsonic tunnels. The compressor costs would run multi million dollars per hour. He wouldn't give a price. He said Airforce staff would give you data if you had a official test matrix program. So you never saw your project in the tunnel only the data. In the test matrix program you specify what you want let's say a drag coefficient of a rocket airframe or fighter jet component at a Mach number you name. Your essentially asking to borrow a national defense strategic asset run time. They are rather busy with hypersonic weapons design tests. There are very very few places globally that do this testing. NASA has closed many old very capable tunnels too used for shuttle design which is a tragedy. The AEDC director recommends contact UTSI if you need that kind of service on a limited budget. NAS is going to be for fortune companies with millions of dollars to spend.

Maybe that college in Australia on HiFex or whatever that scramjet launch was would have a contact too. Or a very well off aerospace college. Once you get to Mach 6 your looking at government massive federal research grant or none at all for "real" tunnel data not CFD. The CFD will have limits.
 
University of Tennessee Chattanooga's wind tunnel is limited to Mach 1. The maximum useful Mach number was derated to Mach 0.8 because the brilliant designer didn't put the drain hole on the bottom so over the years moisture has rusted the pressure vessel internally. Hey engineers are humans too! The testing area is limited to 1" x 1" x 1" objects for actual tests. The CFD virtual wind tunnels are math models by Dr. Sreenivas a hypersonics flow expert at the Sim Center which virtually go to M25. But you'd need a CAD 3D file meshed. There's a low speed wind tunnel in fluid mech lab that goes to 60mph for larger models 5" x 5" x 12"?

UTSI has a Mach 4 wind tunnel. They are well equipped for advanced research. UTC doesn't have an aeronautical/aerospace program but a few professors have aerospace PhD with some experience in industry.


Anyone know if sim programs such as RASAero of OpenRocket give the total pressure,i.e., static pressure plus dynamic pressure during the flight? At the highest speeds the altitude will also be high which means the static pressure will be greatly reduced. Then it may not be at Mach 6 you have to worry about for fin flutter, but at a lower velocity but higher static pressure.

By the way in that list I cited above, it was giving stiffness with respect to weight. Then the carbon fiber does not have 10 times the stiffness as aluminum in absolute terms, but only relative to weight. Actually, a more relevant measure would be stiffness for the same thickness. That's given here:


2. Stiffness and strength of material at the same element wall thickness

Very often design engineers look for material that will enable them to manufacture a component identical to an aluminium one in all dimensions– including thickness. The tables below show comparisons regarding the stiffness and strength of a component of the same thickness made from aluminium, steel and carbon fibre. Note that the component made from carbon fiber of the same dimensions will be 50% lighter than an aluminium one and more than 5 times lighter than a steel one. You will find out more in section 3. Weight / density of material.
Stiffness and strength at the same wall thickness: for aluminium, steel and two-direction carbon fibre:
AluminiumSteelTwo-direction carbon fiber – common modulusTwo-direction carbon fiber – improved modulusTwo-direction carbon fiber – highest modulus
Stiffness (Young’s modulus)Unit: GPa6920090,5132190
Ultimate strength (Tensile Strength – Ultimate Strength) Unit kN · m/kg5001000800368126

Stiffness and strength at the same wall thickness: for aluminium, steel and one -direction carbon fibre:
MaterialAluminiumSteelOne -direction carbon fiber – common modulusOne -direction carbon fiber – improved modulusOne -direction carbon fiber – highest modulus
Stiffness (Young’s modulus)Unit: GPa69200181264380
Ultimate strength (Tensile Strength – Ultimate Strength)Unit kN · m/kg50010001600736252

Replacement of aluminium with carbon fiber resulted in this diving backplate weight being reduced by 55% (from 700 to 450 gram).
A component made from standard carbon fiber of the same thickness as an aluminium one will offer 31% more rigidity than the aluminium one and at the same time weight 50% less and have 60% more strength.
Use of carbon fiber of higher modulus and one-direction fabric may provide x 4 times the rigidity compared to aluminium at similar or improved ultimate strength.


Bob Clark
 
Despite the stiffness, pure carbon fiber tends to act like a tuning fork. So it's easy to built up resonances in it, which is why carbon fiber guitars are a thing. Pure stiffness isn't ideal, as you want the material to also dampen out any flutter that gets generated. Titanium actually is better for flutter, as is it able to better dampen out the resonance (which is why titanium guitars are not a popular thing). So if you really want to go thin on your fins, some AL6V4 titanium would likely be better for both heat and flutter than carbon. You do now have an adhesion issue if you are doing a composite fincan, as you would have to do the correct surface preparation to get the proper bond to the titanium.

There are probably some interesting core materials you can put into it that would solve the tuning fork issue. But you still have the problem in that you are going to get extra drag as the surface of the fins breaks down from the heating.
 
Some folks don't like the real world answers. They'll argue their point to death. Maybe this question should be posted on Arocket as well. Oh, wait. Never mind. :eyeroll:
 
Real world answers don't always agree with theory or math model predictions based on assumptions of materials or environment conditions. Engineering still includes experimental verification and validation in an interation of design still in use by the most successful companies. Where appropriate destructive testing is still considered. It's not that someone dislikes real world answers. But this phase is hella expensive after an already expensive unique prototype is generated and it fails. By then you hopefully have enough test data and learned experience to iterate the design around whatever weakness that reality showed. Perhaps you'll have collected coefficients to solve more formulas more accurately too if your lucky or have baseline experimental data to compare a theory formula against. Engineers apply mathematicians formulas to real world applications and the application doesn't always translate all gracefully. It can be a bit rough sometimes.

If you notice NTRS experimentally tested a bunch of theories and prototypes to find what works when for what conditions. Sometimes the results offered performance gains when the theories didn't say much promising news or vice versa. It may take multiple prototypes to have a final product. There will usually be an unexpected flaw on something brand new never done before. It's done with math and x, y, or z actually failed in real world for reasons we can't get. It'll be the thing you couldn't sim for whatever aspect or some other technical issue. Design, Build, Test as some companies say.
 
One of the most horrific assumptions I read about was the BD-10 prototype. It was a supersonic light jet home built. Composite structure. The aero designer Jim Bede made a stable aircraft. In internal emails from nearly a decade ago you can read how engineers were arguing. They knew the cross flow aerodynamically affected force loads on the vertical tail. One engineer assumed 60 percent of material strength was maximum material strength. The loads were dynamic in flight not static loads. I don't want to point too many fingers, but it seems the aeronautical engineers were not broadly knowledged in structures testing. They had an entire FEA math model in a computer, they had structural tests (of questionable accuracy to even more questionable standards as strain gauge data from flight tests was ignored), but the tails were too thin or too many real life vortices were causing harmonic vibrations and multi axis forces in directions not predicted or simulated. One flight test shows skin buckling at 340 knots. The yield strength was exceeded. Bede predicted flutter at 400 knots. Two test pilots were killed because a tail surface wasn't designed strong enough and a vendor modified a pin into a linkage in a motor actuator for flaps control surface. A real world Murphy enters the scene... The motor was strong enough to shear the pin that another engineer could have verified. This was a mechanical subcomponent of the entire airplane design which was faulty. The NTSB assigned designer error as blame for the two crashes. One flight had tail shear off at 370 knots. The Internet emails on google are just chilling with the company staff arguing theories and the reality was they didn't know fully. Burt Rutan on the other hand another Aero designer successfully designed Space Ship one. I think he bothered to have Varieze wind tunnel tested at Langley. You can see the tail vibrating on rentry. Even for Burt with X-15 program experience there were limits uncovered by testing. I know it's not rockets but new prototypes have limits. To FEA turbulence you need experimental data a prof told me, and if you don't have data then what!?? My opinion they couldn't predict the cross flow. Hey I'm just pissing a real world scenario here. Where even experienced professionals messed up. Even the X-15 had two mechanical pumps vibrate and interfere.
 
One of the most horrific assumptions I read about was the BD-10 prototype. It was a supersonic light jet home built. Composite structure. The aero designer Jim Bede made a stable aircraft. In internal emails from nearly a decade ago you can read how engineers were arguing. They knew the cross flow aerodynamically affected force loads on the vertical tail. One engineer assumed 60 percent of material strength was maximum material strength. The loads were dynamic in flight not static loads. I don't want to point too many fingers, but it seems the aeronautical engineers were not broadly knowledged in structures testing. They had an entire FEA math model in a computer, they had structural tests (of questionable accuracy to even more questionable standards as strain gauge data from flight tests was ignored), but the tails were too thin or too many real life vortices were causing harmonic vibrations and multi axis forces in directions not predicted or simulated...

Thanks for that. Surprising they didn’t do wind tunnel tests to reveal these vortical and turbulence effects.

Bob Clark
 
I have two solid carbon plate MD rockets. One is a 38mm MD the other a 54mm MD, both were all CF kits and I did a single 3K 2x2 twill CF layup on both under vacuum. I also have a laminated G10 core T2T under vacuum for a G12 kit, which is a 38mm MD as well as a 3" cardboard with ply core fins that has a single CF layer just laminated on the fins but no vacuum layup.
With all of these rockets one could argue the process is not required for the stresses they may experience, but they are required to push my knowledge on composite layups and hands on techniques forward. I am currently building a 54mm sub-MD using Dragon plate and have a 98MM sub-MD on the drawing board that will also use Dragon plate and that I will finalize the plans for once I get some feedback on the 54mm sub-MD assembly and performance.

The one-directional carbon fiber has twice the strength of the two-directional kind, but only if the stress is in one plane. Would that be the case for fins in the airstream?

Bob Clark
 
Despite the stiffness, pure carbon fiber tends to act like a tuning fork. So it's easy to built up resonances in it, which is why carbon fiber guitars are a thing. Pure stiffness isn't ideal, as you want the material to also dampen out any flutter that gets generated. Titanium actually is better for flutter, as is it able to better dampen out the resonance (which is why titanium guitars are not a popular thing). So if you really want to go thin on your fins, some AL6V4 titanium would likely be better for both heat and flutter than carbon. You do now have an adhesion issue if you are doing a composite fincan, as you would have to do the correct surface preparation to get the proper bond to the titanium.
There are probably some interesting core materials you can put into it that would solve the tuning fork issue. But you still have the problem in that you are going to get extra drag as the surface of the fins breaks down from the heating.

Is there a parameter that would measure this tendency to act as a "tuning fork", or is it purely a matter of the high Young's modulus? By the way, there are other materials that are isotropic and with even higher Young's modulus (measure of stiffness):

...
Aluminum69[4]10
Mother-of-pearl (nacre, largely calcium carbonate)[18]7010.2
Aramid[19]70.5–112.410.2–16.3
Tooth enamel (largely calcium phosphate)[20]8312
Stinging nettle fiber[21]8712.6
Bronze96–120[4]13.9–17.4
Brass100–125[4]14.5–18.1
Titanium (Ti)110.316[4]
Titanium alloys105–120[4]15–17.5
Copper (Cu)11717
Carbon fiber reinforced plastic (70/30 fibre/matrix, unidirectional, along fibre)[22]18126.3
Silicon Single crystal, different directions[23][24]130–18518.9–26.8
Wrought iron190–210[4]27.6–30.5
Steel (ASTM-A36)200[4]29
polycrystalline Yttrium iron garnet (YIG)[25]19328
single-crystal Yttrium iron garnet (YIG)[26]20029
Cobalt-chrome (CoCr)[27]220–25829
Aromatic peptide nanospheres[28]230–27533.4–40
Beryllium (Be)[29]28741.6
Molybdenum (Mo)329–330[4][30][31]47.7–47.9
Tungsten (W)400–410[4]58–59
Silicon carbide (SiC)450[4]65
Tungsten carbide (WC)450–650[4]65–94
Osmium (Os)525–562[32]76.1–81.5
Single-walled carbon nanotube1,000+[33][34]150+
Graphene (C)1050[35]152
Diamond (C)1050–1210[36]152–175
Carbyne (C)[37]32100[38]4,660
https://en.wikipedia.org/wiki/Young's_modulus#Approximate_values

These materials being isotropic mean you wouldn't have to worry about the plane direction of the stress as with carbon fiber.

Tungsten has a high stiffness, and would also give excellent heat resistance. Unfortunately, it is 8 times heavier than aluminum. Tungsten carbide has even higher stiffness, and good temperature resistance. It is still 6 times heavier than aluminum though. Osmium like tungsten is quite heavy.

According to this list, silicon carbide might be the best bet. It has multiple times higher stiffness and is only 25% heavier than aluminum. It also has moderately good temperature resistance.

Bob Clark
 
Tough, strong, dense, stiff. Please don't pretend like those are all the same thing. After you do young's vs. density, add a dimension of toughness vs. cost.

Aaaaand we're back on familiar territory because *shock* these aren't surprises. Al, CF, etc. are used precisely because of where they sit in that space.

Osmium is frangible, highly toxic, and flammable-to-explosive btw.
 
I know in destructive lab testing like mechanics lab metals exhibit predictable permanent deformation failure above yield strength. The stretching and elongation is predictable for metals up until yield strength. So you can load it and stretch it to a known point and easily predict when it will fail a lot easier than some other materials. On paper metal might be inferior to other exotic materials, but in a lab it's not going to randomly shatter at any loading like a polymer or brittle material can. There are professionals here that have a lot more work experience with material selection than me. Metals offer economical heat treatment for increased stress regions and performance enhancements by changing molecular level structures. Cold drawing processes offer surface hardness increasing too. I don't have a material science book anymore but there were significant advantages to metals for being cost effective. Diffusion processes on industrial level can increase to a precise depth the surface finish and material properties of metals by chemical coatings literally infused into materials. Nitriding processes are used on chrome moly steel hammer forged military gun barrels for increases longevity while not messing with accuracy or precision of complex geometry rifling. Other chrome plating was destroying tolerances on parts affecting accuracy slightly. This diffusion process is just better for keeping part dimensions. Jet Turbine blades and other high performance applications have other chemicals used that I'm not familiar with. All kinds of companies that can coat and diffuse chemicals into metals. I've heard Pratt and Whittney even does chemical milling on aerospace parts.

I'm more limited in that knowledge. Done a few theory book problems years ago. Not an expert by any means. There's a lot more out there in real world to know and learn. I'd want to know the hardness to for machining reasons. If it's harder than steel it might be a pain in the arse to machine quickly.
 
Something like a crank slider with an LVDT and a few accelerometers and velocometers with oil filled dampers can help find vibrations properties of materials experimentally. I don't know much of linear vibrations to be much help.
 
Tough, strong, dense, stiff. Please don't pretend like those are all the same thing. After you do young's vs. density, add a dimension of toughness vs. cost.

Aaaaand we're back on familiar territory because *shock* these aren't surprises. Al, CF, etc. are used precisely because of where they sit in that space.

Osmium is frangible, highly toxic, and flammable-to-explosive btw.
There's a lot of important material values then there is a bit of practical what can engineers do with X material type in manufacturing or how does it experimentally fail and is that failure predictable? Some material post processes offer superior properties economically. Some superb on paper materials are a nightmare to try to make into any useful shape. Machinists always b*tch about how Titanium or Zirconium are horrid to work with from their prespective of making the part. The machinists would want aluminum for ease of tool bit life and fast cutting speeds. They can cut about six times the depth on a single tool bit pass on aluminum compared to steel which saves the engineer and the company a ton of labor time. Until ultrasonic machining became popular it was considered impossible to machine ceramics. You might even be interested in thermal expansion properties of a material to predict how much it expands as it heats up from a high Mach number for example which would affect part interference and fitment between components in an assembly. Dissimilar materials have seized up jet engines at extreme performance envelopes with chemical milling tolerances so tight. You could wind up with a nosecone and body tube not separating by thermal expansion rates being vastly different on extremely tight tolerance parts. Just rambling.
 
Back
Top