Since CAD and finite element analysis can design force vector control in car crashes, a metal container could be designed to fold under tremedous pressure into a very small volume.
This coffin, with a loaded density greater than 1.08 g/cm3, would have blocked holes that *extrude outwards at crush depth*. As the coffin drops through the water column the straining holes will open as the container crumples.
The type of metal gifted to the departed can be chosen which, of course, sets folding calculations and construction. If a lasting material is used, an epitaph placque can be arrange for future submariners, and wildlife to use. In this case another design constraint is used to make sure the restful mark lands the right way up.
No teeth will get cleanned but the circle of life has just got much wider.
*blow inwards at a settable depth* refuted by [8th of 7]-- wjt, Apr 10 2020 // blocked holes that blow inwards at a settable depth.... the straining holes will open and the container will procede to crumple. //
If holes open, the interior and exterior pressure will equalize. There will be no net force on the exterior, hence no crumpling.
[-] bad physics.-- 8th of 7, Apr 10 2020 True that, the holes have to squeeze outwards on compression. Overal concept is still good as it is designed to collapse.
Although couldn't the one plug moving in, be a linchpin in holding the structure. Therefore loss of the pin collapses structure, extruding out other pins.-- wjt, Apr 10 2020 // the holes have to squeeze outwards on compression//
Unless you use a gas generator, or some other pressure source, that's not possible.
Structural collapse as a whole can be used to leverage outward movement of some small areas, but the net movement over the whole surface must always be inward.-- 8th of 7, Apr 10 2020 The vessel wall collapse is vectored, by design, into specific folding that maximises* the squeeze from the sudden pressure equalisation.
*Numbers of approximately 900:1(a bit from the bottom) permitting.-- wjt, Apr 11 2020 A human body is mostly water, which is not noticeably compressible; the same goes for mineralized components.
If you fully immerse such a body in water, wait for it to stop thrashing, and then steadily increase the pressure, it will not "crumple". It will be almost unchanged. Water will infiltrate any remaining voids, any gas will compress; but over all there is not much effect. If the pressure is then slowly diminished to normal, the effect is reversed.
Problems with super-deep diving relate to maintaining a volume of free gas within a high pressure system, and the effects on membrane interchange. The actual pressure isn't so much of an issue.
Fish swim around quite unpeturbed at abyssal depths. They don't crumple either. They are in equilibrium with their environment.-- 8th of 7, Apr 11 2020 An air filled coffin will, especially if the deformation includes pop out extrusion holes (more shape change for more fluid stuff) and folding that vectors force for mechanical advantage.-- wjt, Apr 11 2020 The container will deform until all compressible regions within it have collapsed. Since the body is incompressible, though it may be signficantly distorted by asymmetric forces from the container, it can not experience any further reduction in volume.
For any portion of the container to "pop out" one or more other regions must move in by an equal (in reality, greater) amount. Any other action violates the Conservation of Energy. You cannot get "work" out of nowhere.-- 8th of 7, Apr 11 2020 Abstracting this to a syringe- The plunger is going move the presure differential amount of energy , if the pop outs release before all the energy is spent, then anything that comes out, is a portion off the plunger movement. If the plungers head is design as a bed of rods some fix some sliding, the plunger force is concentrated by design.
This would be fast, and the design of this dynamic force, material, folding entity could even squirt and shut extrusion holes-- wjt, Apr 11 2020 random, halfbakery