Extension Spring

Written by Jerry Ratzlaff on . Posted in Fastener

spring extension

Extension spring is a helical spring like a compression spring with hooks on each end.  The ends of the spring are attached to other components creating a resistance force that absorb and store mechanical energy that opposes the resistance to a pulling force that wants to return back to its origional position.

 

 

 

 

 

spring extension 2Extension Spring load when compressed to length formula

\(\large{ P = T_i + n_s \; d_s  }\)

\(\large{ P = T_i + n_s \; \left( l_i - l_f  \right)  }\)

Where:

\(\large{ P }\) = load when extended to length

\(\large{ d_s }\) = deflection

\(\large{ l_f }\) = final length (compressed)

\(\large{ l_i }\) = initial length (free)

\(\large{ T_i }\) = initial tension

\(\large{ n_s }\) = spring rate

Extension Spring Rate formula

\(\large{ n_s = \frac{ G \; d^4 }{ 8 \; n_a \; D^3 }  }\)

Where:

\(\large{ n_s }\) = spring rate

\(\large{ D }\) = mean coil diameter

\(\large{ n_a }\) = number of active coils

\(\large{ G }\) = shear modulus of material

\(\large{ d }\) = wire diameter

 

Tags: Equations for Spring