Materials and Methods of Construction in Light Structures Page: 26 of 38
This report is part of the collection entitled: National Advisory Committee for Aeronautics Collection and was provided to Digital Library by the UNT Libraries Government Documents Department.
The following text was automatically extracted from the image on this page using optical character recognition software:
N.A..A. Technical Memorandum Y . S15
strength, about 40 kg/m2 (56,890 lb./sq.in.) with an elon-
gation of 18-20'. The reason for this tendency in the
choice of materials is that a vehicle is liable to collide
with stationary objects and in such an event it is better
for the girders to .-bond instead of breaking immediately.
Hence a material is generally demanded with a very great
elongation, which first beocomes permanent above 60% of the
breaking strength. For the latter reason, the use of a
few sposial high-resistance steels, with excellent strength
and elongation, is rendered difficult, since permanent
elongation begins with them at about 30o of the breaking
lod. Those include, for example, the V2a stool, which
has recently become famous.
A similar to:Aency to use metals of somewhat less
strength but greater elongation now seems to be invading
the field of light metals. This tendency is increased by
the fact that the softer materials, like duralumin and
lantal which have breaking strengths of 36-37 kg/mm
(51,200 to 52,625 lb./sq.in.), can generally be worked
cold, so that the expensive and troublesome process of an-
neaoling is eliminated and the softer alloys seem to with-
stand corrosion somewhat bettor,
Especially important is the behavior of those alloys
in sea air and also in sea water for a long time, say
about 1.5 years. While the strength of the material, even
in the unstressed parts, diminished only about 10%, the
elongation diminished 60-70% in places, and finally be-
came entirely too small when its initial elongation was
only 10-12%. The corrosion of the material in combination
and its prevention, i.e., the preservation of the individ-
ual parts, might well be determinative therefore in the
choice of the material. At present, however, there seems
to be no reliable means of protection for light-metal al-
loys, such as the galvanizing of steel. Opinions differ
regarding the effect of sea water oin the various alloys.
On the wholo, the so-watof resistivity of duralumin tand
lautal is practically the same, while that of the other
alloys is somewhat poorer. In combinations of stool and
li ght-metal alloys the light metal does not appear to be
the endangered part. According to experiments which have
been verified b- the material testing section,'the light
alloys beem'to change their tole with respect t o iron, ac-
cording to the duration of the experiment, While iron and
steel at first stand higher than the light-metal alloys in
the electrolytic row, a, change seems to occur after 24
hours, i.e., in structural parts containing both light mot-
Here’s what’s next.
This report can be searched. Note: Results may vary based on the legibility of text within the document.
Tools / Downloads
Get a copy of this page or view the extracted text.
Citing and Sharing
Basic information for referencing this web page. We also provide extended guidance on usage rights, references, copying or embedding.
Reference the current page of this Report.
Rohrbach, Adolf. Materials and Methods of Construction in Light Structures, report, May 1929; (https://digital.library.unt.edu/ark:/67531/metadc65364/m1/26/: accessed May 24, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.