## PSN-L Email List Message

Subject: Re: Peters study of complex friction
From: ChrisAtUpw@.......
Date: Thu, 25 Oct 2007 16:53:08 EDT

```In a message dated 25/10/2007, johnjan@........ writes:

This is  an interesting point that Randall makes.  I suppose if there
is  always some movement due to microseisms, then the static friction
will not  come into play...  but maybe not .... at the end of each
swing it may  be a factor anyway, causing the response to be nonlinear.
Hi All,

If you have simple rolling of a hard cylinder /  sphere on another hard
surface, no direct friction will be involved, although a  small loss will occur
as the rolling surfaces are elastically compressed. If you  have any sliding,
the movement will alternate from one stick / slip  situation to another in
small jerky steps.

I wonder  if there are also complexities of this sort in other types of hinge
that  involve flexure of a material?
In the V suspension shown, vibrations will tend to  flex the rods and
will probably markedly increase the loss in the suspension due  to sliding

Regards,

Chris Chapman

In a message dated 25/10/2007, johnjan@........ writes:
<=
FONT=20
style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size=
=3D2>This is=20
an interesting point that Randall makes.  I suppose if there is=20
always some movement due to microseisms, then the static friction will=
not=20
come into play...  but maybe not .... at the end of each swing it=
may=20
be a factor anyway, causing the response to be nonlinear.
Hi All,

If you have simple rolling of a hard cylinder /=
=20
sphere on another hard surface, no direct friction will be involved, althoug=
h a=20
small loss will occur as the rolling surfaces are elastically compressed. If=
you=20
have any sliding, the movement will alternate from one stick / sli=
p=20
situation to another in small jerky steps.
<=
FONT=20
style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size=
=3D2>I wonder=20
if there are also complexities of this sort in other types of hinge that=20
involve flexure of a material?
In the V suspension shown, vibrations will tend=
to=20
flex the rods and will probably markedly increase the loss in the suspension=
due=20
to sliding friction. http://home.earthl=
ink.net/~meredithlamb/id1.html

Regards,

Chris Chapman
```