Safety / containment netting

[E.OGull]

Hi,

I have to design a safety net to contain glazing panels that may fail and fall.

The manufacturer indicates a netting absorption energy.

Initially I thought that if the potential energy of the falling glass exceeded that netting absorption energy, the net would fail.

Then a colleague corrected me an said that the absorption energy means the energy the net itself can take without transferring it to the supports where the net is fixed.
Hence he said "if the energy of the glass does not exceed the netting absorption energy, the supports are to withstand the dead weight of the glass only".

Is the above correct? Would not be always be an additional (on top of mass x gravity) force on the supports, regarding how low the energy transmitted by the glass was and the elastic constant of the net?

Thank you.

 

[dik]

Depending on the height, glazing panels may act as a 'kite' and may not fall vertically.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[centondollar]

Your colleague is not quite correct. "Absorption of energy", in the context of ductile shock absorbers (e.g., tank armour or a safety net) is just marketing for "large area under the strain-stress curve before ultimate elongation and fracture". The internal force developed in the net is causing a support reaction to the places where the net is connected.

Equilibrium must be satisfied. Action, reaction. The closest equivalent to your safety net is a viscous damper: yes, it dissipates energy (in the form of heat), and the effect of that on other parts of the system (masses and springs) is modeled as a force: "F_damping = c * v", where "v=velocity" and "c = damping coefficient" (units "Newton*seconds / meter").

 

[E.OGull]

Thank you for your reply.

How could I estimate then the load sharing between both the netting and the supports?

Manufacturers only provide:

1) Netting energy absorption (what is this value telling us? Is it okay if is exceeded?)
2) Resistance of suspension ropes ('supports' to the structure)

However there is no guidance in resistance force of the netting itself, and I need to justify the netting is suitable.

Regards.