Today's Message Index:
----------------------
1. 09:57 AM - Re: Solder splices/connections (Robert L. Nuckolls, III)
2. 08:51 PM - Strobe Grounding (mike@vision499.com)
Message 1
INDEX | Back to Main INDEX |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Re: Solder splices/connections |
At 04:29 PM 9/28/2016, you wrote:
>The stress riser that occurs at the interface between wire strands
>and solder filled wire strands if not mechanically supported is a
>candidate for fatigue failure due to vibration induced flexing of the wire
>
>This is true of field splices and soldiered pin/wire connection.
>
>Good mechanical support/strain relief is imperative to prevent
>fatigue failure of the connection/soldier joint.
Yes, stresses due to flexing of any material is
a function of thickness/diameter of object and
the magnitude of the bending . . . which under
vibration gives rise to cyclical tension/compression
forces on the material. A second of 1" copper rod
flexed through x-degrees will fail in a tiny fraction
of the same cycles impressed on a 0.020" strand of
copper. This is why welding cable is made from a bizillion
strands of copper 'cat hair' as are braided copper
bonding straps . . .
http://tinyurl.com/jxsf55j
. . . are unlikely to fail under flexure stresses
over lifetime of the installation. Whether or not
a solder-solidification of strands presents a more/less
severe stress riser point than a crimp-
solidification is kinda splitting hairs.
When used in a situation that imposes
cyclical forces on the joint, there is
significant risk of failure at the
transition from solid to strands in BOTH
technologies.
This fact of physics gave rise to the double
crimped, 'pre insulated' terminals of all stripe
but most famously, PIDG style terminals
offered by many suppliers for the last
70 or so years.
http://tinyurl.com/zkmh7kj
When the joining is effected with solder,
folks in-the-know strive to achieve two
goals. Join the wires and support the
insulation just outside the junction.
http://tinyurl.com/ju4gvvg
Arguments favoring one process over the other
have no solid foundation in risk reduction.
It's not difficult to apply either process
in a manner that will exceed the service
life of the airplane.
You can mess up a potentially good crimped
installation too.
http://tinyurl.com/hekmvyz
This terminal was observed on an accident
aircraft where, amongst many other shorfalls,
some terminals were not properly installed.
Understand the physics, acquire the tools
and PRACTICE.
Bob . . .
Message 2
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Strobe Grounding |
I have installed a Whelen HDACF Power Supply in my composite aircraft
and the instructions make no mention of grounding the shield in the
cables to the strobes.
Should I ground the shield and if yes should it be one or both ends.
Thanks
Mike
Other Matronics Email List Services
These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.
-- Please support this service by making your Contribution today! --
|