Chain Design
There are 3 types of chains in the fender system: tension chain, weight chain, and shear chain. The tension chain is to protect the fender from the damage while under local compression. The weight chain is to support the weight of front panel and the face panel. The shear chain is to protect the fender from damage while in shear deflection.
The following items should be noted in chain design:
- The chain dimension should be as exact as possible, not too loose or too tight
- The chain can not be twisted as this reduces the load capacity
- Open link is preferred
- The initial angel of the chains is important. Normally weight chains are set at a static angle of 15~25 degree
- All the chains must be with safety factors which should be 2-3 times of the work load
- Shackle selection: the dimension of the shackle is usually the same as the dimension of the chain , but if the shackle is required to bear the same load with the chain, thicker shackle is preferred
- Selection and calculation of chain
Lb = Fs . LW
H2=H1-D
Ø2 = a sin [ ( H1 – D ) / L ]
T= ( μ* R +W ) / 9.8*n*cos Ø2
R: combined reaction of all rubber fenders ( KN)
μ: friction coefficient of face pad material ( 0.2 )
W: the total weight of frontal panel, face pad and fender
Ø1: static angle of chain (degree )
Ø2： dynamic angle of chain (degree )
H1: height of fender before deflection ( m)
H2: height of fender after deflection ( m)
L: length of chain ( mm)
T: safe working load of chain ( T)
D: fender compression ( mm)
N: number of chains acting together
