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Second Moment of Area calculation?
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[QUOTE="SteamKing, post: 4939182, member: 301881"] I think for the welding illustrated in the OP, it would be simpler to calculate the MOI about the top of the section, and then apply the PAT to calculate the MOI of the welding about the centroid, which is located y-bar below the top. In this case, the MOI of the vertical lines would be calculated about the top end and would be d[SUP]3[/SUP]/3 for each side. You have two vertical sides, so the MOI is thus 2d[SUP]3[/SUP]/3, and the MOI of the top piece is negligible. To correct the MOI from the top to the centroid, you must subtract A*(y-bar)[SUP]2[/SUP] from the MOI about the top, so MOI(centroid) = 2d[SUP]3[/SUP]/3 - A*(y-bar)[SUP]2[/SUP], and I have seen the formula for the MOI shown on the image attached to the OP on other sites, so it has been copied without anyone checking to see if it is in its simplest form. That particular formula boils down to this: MOI(centroid) = 2d[SUP]3[/SUP]/3 - 2A*(y-bar)[SUP]2[/SUP] + A*(y-bar)[SUP]2[/SUP] which is just MOI(centroid) = 2d[SUP]3[/SUP]/3 - A*(y-bar)[SUP]2[/SUP] You can always verify the MOI calculation by calculating the inertia of each weld segment about its own centroid, transferring to the top of the weld pattern, and then applying the PAT to correct the MOI back to the centroid of the pattern. [/QUOTE]
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Second Moment of Area calculation?
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