 energy absorption

# Industrial

### Horizontal Impact Kinetic energy to be absorbed Energy due to drive force to be absorbed Ed = FdS Total energy to be absorbed ET = Ek + Ed Maximum impact force due to inertia Total maximum impact force Design mass for buffer FT = Fi + Fd Design mass for buffer #### Summary of notation

To avoid confusing conventions within calculations always use SI units in formulae then convert to more appropriate units if required.

 Notation Quantity SI Unit M Mass of body kg Me Buffer design mass kg S Buffer stroke m Ek Kinetic energy J Ed Energy due to drive force Total energy J ET Total energy J v Velocity m/s Fi Inertial force N Fd Drive force N FT Total force N n Number of buffers in parallel - ξ Efficiency -

#### Worked example

Eg. Consider a body of mass M = 20000kg (20 tonnes), moving at a velocity (v) of 1.5m/s with a drive force (Fd) of 20kN (20000N).

To find energy absorbed:
Ek = 1/2 Mv2 = ((20000kg)x(1.5m/s)2)/2 = 22500J = 22.5kJ

Let us therefore select a Type21-150
Ed = Fd.S = 20000N x 0.15m = 3000J = 3kJ

Total energy to be absorbed
ET=Ek+Ed=22500J+3000J=25500J=25.5kJ

To find the maximum impact force:
Fi max = Ek / (S. ξ) = 22500J / (0.15m)x(0.8) = 187500N = 187.5kN

Fd max = 20000N = 20kN

F T max = F i max + F d max = 187500N + 20000N = 207500N = 207.5kN

To find buffer design mass for metering pin selection:
Me = 2.ET / (n.v2) = 2 x 25500J / (1 x (1.5m/s)2 = 22667kg = 22.667 tonnes

Select a Type 21-150 buffer with a dynamic capacity of 30kJ and a maximum permissible load of 250kN, to meet these requirements.Therefore select metering pin code 155, for masses up to 25000kg (25 tonnes).