My interest is in the subject of light hovercraft. Recently the subject of guarding of thrust propellers has become important.
Most hovercraft use axial fans or propellers to provide thrust, and these are normally contained within a guard or duct. There is the need to be able to show that a particular guard construction is capable of containing a failed blade of known kinetic energy.
Guards are usually constructed of GRP or wire mesh, and are sometimes reinforced with kevlar. Typical blade kinetic energies are in the region of 2000J - 3000J.
Since many craft, and therefore guards, are one-offs built by amateurs, there is the need to provide a means to calculate, or otherwise verify, the capability of a guard to contain the given KE. This appears to be somewhat of a problem!
Can anyone suggest any means to verify guard capability without resorting to potentially expensive ballistic testing?
References to prior work, calculation methods?
Or references to ballistic containment materials that can be supplied with proven performance to contain 'x' J from which a guard may be constructed?