What does envelopes mean here?
not only different design envelopes but also different spring rigidity progressions over the compression path can be achieved

ОГИБАЮЩИЕ?

Question

What does envelopes mean here?
not only different design envelopes but also different spring rigidity progressions over the compression path can be achieved

ОГИБАЮЩИЕ?

Answer

'Envelope' comes from flight engineering.  It describes the range of values and situations that would result in stable flight.
If a pilot 'pushed the envelope', it referred to pushing the airplane to its limits.
In engineering in general, a design envelope would be the range of forces that a structure would be able to withstand.

Answer

Answering questions on italki can really be some sort of imagination-training sometimes. How about some context? It might refers to some specific term in physics, or so.