5003 Lectures - Faculty of Engineering and Applied Science

E5003 - Ship Structures I 59
© C.G. Daley
When we have bending moments in both y and z, there will be a line of zero axial
stress that we call the heeled neutral axis. This is not necessarily aligned with the
total moment. To find the heeled neutral axis we solve for the location of zero stress;
σ
X
− M z cos θ M y sin θ
w
w
= 0 =
+
,
I NA
I CL
solving for z in terms of y , we get;
I NA z = tan θ ⋅ y ,
I CL
I NA
where we define: tan ψ = tan θ
I CL
z = tan ψ ⋅ y
ψ is the angle of the heeled neutral axis from the y axis;