Re: Determining balsa stiffness

From: markdrela <drela_at_mit.edu>
Date: Sat, 14 Jan 2006 17:56:36 -0000

--- In Indoor_Construction_at_yahoogroups.com, Don Slusarczyk
<don5490_at_s...> wrote:

> Also the weight of the sheet can be negelected when vertical. In a
> horizontal deflection test, the weight of the sheet makes a big
> effect on thinner sheets.

No. It's just the opposite.

In the horizontal deflection test the initial tare reading eliminates
any effect of the weight of the beam.

In the vertical buckling test, the weight of the sheet may or may not
be significant -- it depends on the thickness/length ratio of the
sheet. It looks like the online calculator subtracts the weight of
the sheet from the buckling load, but this over-corrects for the balsa
weight. Instead, about half of the weight of the sheet should be
subtracted, since that then gives the average compressive load over
the length of the sheet.
Received on Sat Jan 14 2006 - 09:56:49 CET