Section 3 Method for Collision Damage Assessment

3.1 Objectives

3.1.1 This Section describes a simplified analytical method which may be used for collision damage assessments. Please see footnotes of Section 4 on how the methods were originally developed. ^footnote ^footnote Alternative methods, subject to Lloyd’s Register’s agreement, may be considered.

3.2 Details of the simplified method

3.2.1 It is considered that the collision damage to the struck ships is large and heavy because the damage penetration in the order of B/5 is to be investigated. This means the side shell will be ruptured and decks or stringers or webs etc. could be crushed.

3.2.2 Two types of energy absorption mechanisms may be considered: one is tension of structural members and the other is crushing of structural members. They are illustrated in Figure 1.3.1 Illustration of crushing and tension modes in collision damages.

Figure 1.3.1 Illustration of crushing and tension modes in collision damages

3.2.3 The energy absorbed by destroying ship structural members in tension mode can be determined from:

where

σ₀	=	is the flow stress of the materials and taken as the average of yield stress and tensile strength,
ε_c	=	is the critical rupture strain of the materials, and
R₁	=	is the materials volume of the damaged structural members in tension mode.

3.2.4 The energy absorbed by destroying ship structural members in crushing mode can be determined from:

where

σ₀	=	is the flow stress of the materials and taken as the average of yield stress and tensile strength,
R₂	=	is the materials volume of the damaged structural members in crushing mode,
t	=	is the structural member thickness, and
b	=	is the width of the structural member.

3.2.5 The total absorbed energy can be obtained from summation of the energy absorbed by all damaged structural members: