Where to find formulas for acceleration of compressed steel tubes

[mhl]

Hi all

Looking for simple formulas to describe maximum acceleration of steel tubes when tubes are compressed and suddenly released when submerged in water (dont know if the water does anything else than supply buoyancy).

Please, also feel free to comment freely on the topic and formulas you might state...

Hope you can help...


thanks

mhl

 

[xez]

Compressed how? Axially, radially, filled with compressed air, etc. etc. Your description of the problem isn't sufficient
to even begin to understand the question let alone answer it.

As for simple equations, where are simple equations, and
then there are usefully correct equations; the two aren't
always overlapping when you're dealing with something
like drag due to motion in water. There's a reason that
engineers often build scale models of things and test them
"for real" in water tanks rather than relying on the accuracy
of estimates from fluid flow / drag calculations; it's
often easier to build and test the thing rather than model
it sufficiently accurately even with complex equations and
computer models.

If it's just a question of axial acceleration of a tube through
water given a certain 'rocket' thrust from compressed air
inside the tube released from an axial nozzle in the rear,
then you could probably find a good simple formula for
the drag of a cylinder of a given size in water, and the
thrust will just be the simple rocket equation due to
the momentum of the release of the gas given a certain
escaping gas flow rate due to the pressure differential of
the gas vs. the water and the size/performance of the
nozzle the gas escapes through. That's about as simple
as that gets, pretty simple to estimate with simple
math and a notepad, but still not trivial.

Unless you're talking about the mechanical relaxation /
oscillation / 'springing' / ringing (like a bell) /
expansion (like a bellows) of a structurally compressed tube
under water in which case, well, good luck, that's likely
a lot more complicated due to (in)elasticity, friction,
drag, heat, possibly turbulent fluid flow, etc. etc.

The simplest case would be like letting go of a coiled
tube spring underwater in which case you're back to
estimating the cylinder's drag and the the evolution of
the 'spiringing away' based on the water's drag and the
F=mx tension in the spring and how long the spring will
be able to push against its dock...

 

[ravenprp]

Hi mhl,

Thank you for your question. The acceleration of compressed steel tubes can be described using the principles of fluid mechanics and structural mechanics. The formula for acceleration in this scenario would depend on factors such as the material properties of the steel tube, the dimensions of the tube, and the density and viscosity of the water it is submerged in.

One potential formula that could be used is the Bernoulli's equation, which relates the velocity of a fluid to its pressure and density. This equation can be used to calculate the acceleration of the water surrounding the compressed steel tube, which in turn can affect the acceleration of the tube itself.

Another relevant formula is the Euler's buckling formula, which is used to calculate the critical buckling load of a column or beam. In this case, the compressed steel tube can be considered as a column and the water pressure acting on it can be factored in to determine the maximum acceleration it can withstand before buckling.

Other factors that could affect the acceleration of the compressed steel tubes include the compressive strength and Young's modulus of the steel material, as well as the rate at which the tube is being compressed and released.

I hope this information is helpful. It is always important to consult with a professional engineer or conduct thorough testing to accurately determine the acceleration of compressed steel tubes in a specific scenario. Best of luck with your research!