4.Speed Correction Factor
Relating the elasticity of rubber, the following circumstances could affect the reaction force and
energy absorption capacity of the fender.
[a] Aging(Harder)
[b] Compression speed effect(Harder)
[c] Temperature(Softer to Harder)
[d] Repetitive compression(Softer)
It is general that the amount of each effect is not clear, and the effects are considered to be unity in total.
On the other hand, the each amount of effect is different and the effect by compression speed can be principal.
As far as the design is made bad on Japane Standard, we had better consider some safety in
energy absorption capacity by speed effect. But as safety factor is considered independently or in other
condition in British Standard or German Standard, we could pick up the speed factor and make the effect clear.
There is a manufacturer who applies the wrong speed factor without note in the description of performance in the catalog. Here we would like to explain what are important in the consideration of speed effect which will be called "speed factor."
[1] Speed factor isn't constant by absolute compression speed(mm/c)but relative
compression speed(%/c)in fender deformation.
[2] Compression speed changes from berthing speed to nil in berthing process.
When we consider this factor in design, we should take the fact into consideration.
As a conclusion, the speed effect is different from the height of the fender(the distance
from quay surface to the top of buffer)and we should calculate the effect with the
consideration of berthing process. (At the end of berthing process, the speed becomes nil).
Plea contact us for further information if you have interest.
Where 2 : Installation pitches of fenders (m)
: Bent radius of board side of ships (m)
h: Height of the fender when effective kinetic energy of vesls is absorbed As the bent radius is usually not known,
we can estimate the radius by ship's length (L) and ship's width (B).h 2
r 2 2222
+-h ( )8B L 2
B -(r-h)
2
(9.1)
(9.2)
Module of berthing structure provides the final pitch of fender installation.Some examples are shown as recommendation of fender layout.
For continuous quay the installation pitch is recommended to be less than 15 percent of the ship.
