Another way to document equations in Excel is the Equation Editor. This is the same editor that’s used in both PowerPoint and Word.
It may be helpful to create a location in your spreadsheets to display the main governing equations that you’re using, whether it’s one section of a spreadsheet or on a separate sheet in the workbook.
In Worksheet 01f, there are two equations that might not be understood by someone who’s not familiar with these calculations – static deflection and natural frequency. We can use the Equation Editor to show these equations on the spreadsheet.
You can go to the Insert tab > Equation, or you can use the shortcut button in the Quick Access Toolbar if you added it previously (see Chapter 1, Section 1). Either one will add a blank equation object on the sheet.
To enter in your equation, you could use the buttons in the ribbon:
However, this method is slow and awkward. If you’re creating equations frequently, it’s much easier to learn the shorthand notation that the Equation Editor uses.
Most of the shorthand notations for the equation editor start with the backslash – the \ character found just above the “Enter” key on most keyboards. You can type \delta, and when you press the spacebar, the Equation Editor will transform it into δ.
To make a subscript, use the underscore: _ (Shift + hyphen). The letter or letters that follow will be made subscript after you press the spacebar. Superscripts are made using the caret symbol: ^ (Shift + 6).
You can use parentheses as you would in handwritten calculations, or to keep expressions grouped together in fractions (similar to a scientific calculator). The forward slash (/) is used to enter a fraction.
Thus, to enter in the equation for static deflection:
Open the Equation Editor and type:
\delta _st =Fa^2 (a+b)/3EI
Remember to press the spacebar after each shorthand that needs to be converted. However, be sure not to press space between the characters “3EI” so that the Equation Editor places all three in the denominator.
We’ll also include the equation for the natural frequency of the shaft on this spreadsheet. Click out of the first equation before adding a new one. You may have to resize the equation objects to fit the equations. Go to Insert > Equation or the shortcut in the Quick Access Toolbar.
The equation for natural frequency includes a square root. The shorthand for the square root operator is \sqrt. In order to encase the expression underneath the square root, follow the \sqrt immediately (no space) with the desired expression in parentheses. Press spacebar and the square root operator will extend to cover the entire the expression.
We now have all the shorthand commands we need to enter in the equation for natural frequency:
Type in the Equation Editor:
f=(1/2\pi) \sqrt(g/\delta _st)
If you end up with π outside of the fraction, you probably pressed space after the 2. It’s also easy to accidentally place δst outside the fraction by pressing spacebar after g/. Check your spaces carefully.
Another problem you may come across with the Equation Editor comes up if you click outside the equation editor, then click back in again and start to type. Excel may think you’re typing text, and not an equation, and it won’t convert your shorthand into symbolic notation. You can spot this problem by looking at the alignment of your equation – if it’s left-aligned, then it’s being interpreted as text (equations will be center-aligned). To fix this, just delete any text you’ve entered and press the left arrow key until the equation is highlighted in light blue:
Then you can start typing again.
For a list of shorthand notations commonly used in the Equation Editor, see this link.