. Railway mechanical engineer . DEPAiq^ETm TABULAR METHOD FOR CALCULATINGMOMENT OF INERTIA BY WENDEL J. MEYER The following method for calculating moment of inertiahas several advantages: the component calculations arerecorded and may be checked at any time; the method easilylends itself to the use of the slide rule; if the section bechanged after a calculation is made, it is not necessary tomake an entire new one: deductions for rivet holes are easilymade. The moment of inertia (It) of a compound section aboutany axis or base line is equal to the sum of the moments ofinertia (I) of the compon
. Railway mechanical engineer . DEPAiq^ETm TABULAR METHOD FOR CALCULATINGMOMENT OF INERTIA BY WENDEL J. MEYER The following method for calculating moment of inertiahas several advantages: the component calculations arerecorded and may be checked at any time; the method easilylends itself to the use of the slide rule; if the section bechanged after a calculation is made, it is not necessary tomake an entire new one: deductions for rivet holes are easilymade. The moment of inertia (It) of a compound section aboutany axis or base line is equal to the sum of the moments ofinertia (I) of the component parts about axes through theirown centers of gravity plus the areas (A) of the component ?A8jZJe_. Used as Basis for Calculations parts multiplied by the squares of the distances (d) fromtheir own centers of gravit) to the base line, or lb = I + A d=and I = lb — A d- Applying the latter equation to the compound section as awhole, there results: I„. = I,. — At C-where /»• is the moment of inertia of the compound sectionabout its neutral axis, /1> is its total area and C is the dis-tance from its neutral axis to the base line. The accompanying table shows the method applied to acenter sill section. Since the section is symmetrical aboutits vertical center line, it is only necessary to work with halfthe section and then double the final result. The sizes, areas (A) and moments of inertia (I) of thecomponent parts of the section arc placed in the first, secondand last columns, respectively. In the third and fifth col-umns are placed the arms or distances (d) from the centersof gravity of the component parts to some convenient baseline, which usually will be a line through t
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectrailroadengineering
