3310. SumMassProps – An Excel VBA Solution for Summing Mass Properties

Paper

Abstract

Microsoft Excel is a general-purpose spreadsheet program that lends itself to mass properties calculations. There have been many papers written and presented to the SAWE showing differing techniques to use in determining assembly and vehicle mass properties. The problem with these techniques is that they require a portion of the spreadsheet to be used for storage of intermediate results and the equations used become complex and confusing using Excel?s native symbology. This paper introduces a comprehensive solution set for mass property summation using the built-in Visual Basic for Applications macro language extant in Excel. The solution set, ?SumMassProps.xla,? is embedded in an Excel Add-in. SumMassProps is comprised of three increasingly comprehensive custom functions: CCOG, a function to compute Center of Gravity; CMPROP, a function to compute the complete 10 by X mass property tensor; and CMUP, a function that extends CMPROP by also computing the combined independent uncertainty properties of all ten mass property terms in the mass property tensor. The Add-in also includes facilities to aid in setting up and using the functions in a spreadsheet. By using the Add-in paradigm, the solution set becomes available for use in any spreadsheet that is on the user?s computer. By using SumMassProps, the mass property engineer is freed from spending time debugging spreadsheets and re-inventing the wheel to determine a composite body?s mass properties. This solution set ensures that the proper equations are used and implemented in a consistent manner and speeds up production of reports and ?what-if? scenarios.