OCIMF_Mooring_Equipment_Guidelines_(Second_Edition)

50

I

/

Llmllmg Case. Chain

Lifted From Surlace

---........

"

~o \

Cl) \

UJ w

a:

<!)

UJ

0

t!i^30

UJ ...J "'---

"

C)

Z <{

UJ

0

Lt

Cl: 20

RangeOt .. J \

• l

\

Observed Values

\,

:::l

'1

z

;;t'

I

0

\

\

\

\

10

L,""hng Case. \

Chain Flat On

Surface

o I I I I I 1\

o 30 60 90

INTER-LINK ANGLE a, DEGREES

FIGURE F3: APPROXIMATE RELATION BETWEEN ANGLE Cl! AND ANGLE P

The angle a as a f unction of tJ)C diameter ratio D i d and various angles ~ is shown in Figure F4.

The angle a cannot, therefore, be uniquely determined without first having determilled ~, and ~

unfortunately depends on a. Thus a closed form solurion is not possible.

I

F.3 FORCES ON THE CHAIN LINK

A free-body diagram of half a chain link, showing [he forces and moments applied when bent over

a curved surface, is given in Figure FS. The effect of the stud is ignored in tbis analysis.

The force P is the tension in th e cllajn, For the purpose o f analysis. it is as IIIDed th e lens.ion
force P is appljcd at 111 C c(;olrclinc of th e chai n, (n the case of chain on an wlgroovcd s urface,
the tension force P between ch ain link. acts a t an angle a/2 to tb e cham centreline. because I:very
chain link bears on the surface. T bis is an important distinction from t he case of chai.n OIl a gTooved
surface, in whjcb every other chain link is not in contact with the surf ace and thus is under le.nsion
only. The angle at wbich the tensile force P acts on the bent chain link in th e grooved surface case
IS Q. Only the solution of the ungl'o vo:;d surfuc~ case will be addre.ssen here.

The reaction force of the surface agains t the chain link is R. For the half chain link free body

shown, only half (his reaction force applies. Because the chain lies at an angle to the surface, the