Re: [bolger] Re: hollow mast progress
Well, the comparison is a mathematical one - the solid mast is stronger.
I would suggest adding Kevlar strand (or other high-modulus fiber) in the
notches of the bird's mouths.
GHC
I would suggest adding Kevlar strand (or other high-modulus fiber) in the
notches of the bird's mouths.
GHC
>In a message dated 07/29/2000 9:<BR42:<BR28 AM
> Eastern Daylight ,pvanderw@...writes:> I am interested that the
>hollow mast seemed stiffer. I don't see why
>> it would be stiffer than a solid mast of the same material. Anyone
>> have any ideas?
>
>Barring any other variables, the solid mast would be stiffer, but not by
>much. However, it is not easy to make the comparison unless you make a solid
>mast, test it, thencut up the mast and use the (outside) staves to make the
>hollow one for test (well....one could make two masts from adjacent parts of
>a tree and be awfully close :-)
>
>Cheers/Step
>
>
>
>Bolger rules!!!
>- no cursing
>- stay on topic
>- use punctuation
>- add your comments at the TOP and SIGN your posts
>- add some content: send "thanks!" and "ditto!" posts off-list.
Not really a function of weight. THe material works harder and has
better leverage as it gets away from the neutral axis, which, in a
symmetrical piece with normal materials is going to be the center.
The
material that is close to the outside does most of the work. If you
drilled out the center 1/4" of that rod, you probably wouldn't notice
the change in stiffness. In general, stiffness in a round or square
section will go as the 4th power of the width, strength as the 3rd
power. TO account for the hole, stiffness will go as (od^5-id^5)/od
and strength (od^4-id^4)/od unless I'm getting to rusty and have
forgotten too much beam theory. Of course at some point the walls get
too thin and you get buckling. Hope my symbols get across properly.
better leverage as it gets away from the neutral axis, which, in a
symmetrical piece with normal materials is going to be the center.
The
material that is close to the outside does most of the work. If you
drilled out the center 1/4" of that rod, you probably wouldn't notice
the change in stiffness. In general, stiffness in a round or square
section will go as the 4th power of the width, strength as the 3rd
power. TO account for the hole, stiffness will go as (od^5-id^5)/od
and strength (od^4-id^4)/od unless I'm getting to rusty and have
forgotten too much beam theory. Of course at some point the walls get
too thin and you get buckling. Hope my symbols get across properly.
--- Inbolger@egroups.com, "Chuck Leinweber" <chuck@d...> wrote:
> > I am interested that the hollow mast seemed stiffer. I don't see
why
> > it would be stiffer than a solid mast of the same material. Anyone
> > have any ideas?
> >
> > Peter
>
> If you take a 10' x 1/2" dia. steel rod, it will seem pretty limber
compared
> to a tube of the same dimensions and material. I don't know if
this
is a
> function of weight, or if there is something else working here.
Perhaps
> Gregg or some other engineer can shed some light on this subject.
>
> Chuck
> I am interested that the hollow mast seemed stiffer. I don't see whyIf you take a 10' x 1/2" dia. steel rod, it will seem pretty limber compared
> it would be stiffer than a solid mast of the same material. Anyone
> have any ideas?
>
> Peter
to a tube of the same dimensions and material. I don't know if this is a
function of weight, or if there is something else working here. Perhaps
Gregg or some other engineer can shed some light on this subject.
Chuck
In a message dated 07/29/2000 9:<BR42:<BR28 AM
Eastern Daylight ,pvanderw@...writes:> I am interested that the
hollow mast seemed stiffer. I don't see why
much. However, it is not easy to make the comparison unless you make a solid
mast, test it, thencut up the mast and use the (outside) staves to make the
hollow one for test (well....one could make two masts from adjacent parts of
a tree and be awfully close :-)
Cheers/Step
Eastern Daylight ,pvanderw@...writes:> I am interested that the
hollow mast seemed stiffer. I don't see why
> it would be stiffer than a solid mast of the same material. AnyoneBarring any other variables, the solid mast would be stiffer, but not by
> have any ideas?
much. However, it is not easy to make the comparison unless you make a solid
mast, test it, thencut up the mast and use the (outside) staves to make the
hollow one for test (well....one could make two masts from adjacent parts of
a tree and be awfully close :-)
Cheers/Step