Several possible answers -
Some fibers creep at low (15% breaking) loads until they break. Not so
good for guys!
Some creep and stabilize to a fixed strain w/o much change in breaking
strength. Phillystran says set the initial guy load at 15% B.S. and it
will relax to 12% which is the recommended level.
The breaking strength change for most fibers is dependent on stress
cycling history and is complicated.
Other factors also modify breaking strength - moisture absorption, fiber
lubrication, contamination... and fibers are different in how they
respond to these issues.
Fiber ropes are so complex and varied, that I'm convinced that for
permanent guys there are only (IMHO) three proven solutions - EHS,
Phillystran, and solid rod and are used on large commercial towers. It
would be interesting to know if there are 300, 600 or 1000 footers out
there with other guy materials.
Grant KZ1W
On 1/4/2012 9:05 AM, Mike wrote:
> I wonder what the diameter/strength "creep" to?
>
> 74, Mike NF4L
>
> On 1/4/2012 10:52 AM, Joe Subich, W4TV wrote:
>> Grant,
>>
>> On 1/3/2012 10:05 PM, Grant Saviers wrote:
>> > I checked my reference text, "Handbook of Fibre Rope Technology" and
>> > Dyneema has excessive creep vs Kevlar.
>>
>> Thanks for the confirmation.
>>
>> Looks like these Mastrant ropes might be useful for temporary tower
>> installations at 10% preload but would require constant adjustment in
>> permanent service. These ropes might also be interesting for use with
>> an AB-577 or AB-621 with their temporary nature or for guying 80/160
>> meter verticals with their relatively low static loads.
>>
>> 73,
>>
>> ... Joe, W4TV
>>
>>
>> On 1/3/2012 10:05 PM, Grant Saviers wrote:
>>> I checked my reference text, "Handbook of Fibre Rope Technology" and
>>> Dyneema has excessive creep vs Kevlar.
>>>
>>> Dyneema SK60 creeps 0.63% at 15% of breaking load in 100 days. At 30%
>>> load it creeps 9% in 100 days!
>>>
>>> Kevlar 49 creeps 0.041% and 0.05% respectively. A search for "creep" on
>>> the Phillystran web site yielded no hits.
>>>
>>> The Mastrant web site says they are using Dyneema SK75 which another
>>> reference shows 22% creep at 30% load in 20 days
>>> http://www.abcm.org.br/symposiumSeries/SSSM_Vol2/Contents/SSSM_05.pdf
>>>
>>> So the guying application seems wrong for Dyneema fibers. Spectra is an
>>> even worse choice. Polyester creep is about 5x worse than Kevlar
>>>
>>> OTOH, Phillystran is well proven and presumably contains the best Kevlar
>>> fiber for making permanent guy wires.
>>>
>>> Grant KZ1W
>>>
>>>
>>> On 1/3/2012 6:15 PM, Joe Subich, W4TV wrote:
>>>> On 1/3/2012 5:18 PM, K1TTT wrote:
>>>>> Check the original linked page, that place is only selling the 'P'
>>>>> type which is the polyester one(and only on special order at that).
>>>> Check again ... list all the products from that company on the R and L
>>>> site. You will find both the D and the F2-D ropes which are Dyneema
>>>> core (similar in performance/strength to Kevlar). The problem - as
>>>> explained to me - is that although Dyneema will not stretch under
>>>> dynamic load it will "creep" (slowly elongate) under static loads
>>>> like those encountered in guying applications.
>>>>
>>>> 73,
>>>>
>>>> ... Joe, W4TV
>>>>
>>>>
>>>> On 1/3/2012 5:18 PM, K1TTT wrote:
>>>>> Check the original linked page, that place is only selling the 'P' type
>>>>> which is the polyester one(and only on special order at that). The 'D'
>>>>> versions are on the manufacturer's page, and while the specs are
>>>>> better they
>>>>> are still only hd polyethylene rope.
>>>>>
>>>>> David Robbins K1TTT
>>>>> e-mail: mailto:k1ttt@arrl.net
>>>>> web: http://wiki.k1ttt.net
>>>>> AR-Cluster node: 145.69MHz or telnet://k1ttt.net
>>>>>
>>>>> -----Original Message-----
>>>>> From: Wayne Kline [mailto:w3ea@hotmail.com]
>>>>> Sent: Tuesday, January 03, 2012 20:58
>>>>> To: K1TTT; towertalk@contesting.com
>>>>> Subject: Re: [TowerTalk] Mastrant Rope ? guy wire ?
>>>>>
>>>>>
>>>>> My Frist Thought Dave Till I dug into it http://www.mastrant.com/en
>>>>> Wayne
>>>>> W3EA> Date: Tue, 3 Jan 2012 11:57:06 -0600
>>>>>> From: k1ttt@verizon.net
>>>>>> To: towertalk@contesting.com
>>>>>> Subject: Re: [TowerTalk] Mastrant Rope ? guy wire ?
>>>>>>
>>>>>>
>>>>>> thats just a polyester rope not a tower guy material unless you need it
>>>>> for a temporary field day type tower.
>>>>>> Jan 3, 2012 12:43:42 PM, w3ea@hotmail.com wrote:
>>>>>>
>>>>>>
>>>>>>
>>>>>> Hi TT'ers HNY Planning my spring 10 meter tower antenna 5/5 35'-72'
>>>>>> rebuild. The 3/16 guy wire broken up with 502 insulators levels 32'
>>>>>> 64' It's in good shape but has rust wash near there attachment points
>>>>>> ! It's been up 22 years in this acid NE rain a new paint job new feed
>>>>>> lines rebuild the rotors .. why not new guy support. I Was thinking of
>>>>>> doing Phillystran, at least on the top layer. While researching it I
>>>>>> stumbled across a product Sold in the USA by RL Electronics in OH.
>>>>>> Mastrant guy rope !
>>>>>> http://store.rlham.com/shop/catalog/advanced_search_result.php?keyword
>>>>>> s=mastrant+and+mp&x=5&y=5Any TT'ers have any experience with this
>>>>>> stuff ? Have experience with all the old style and new type Philly
>>>>>> stuff and the Fiber-rod. nonconductive guying material . But this is a
>>>>>> new one for me. Thanks 73's Wayne W3EA
>>>>>> _______________________________________________
>>>>>>
>>>>>>
>>>>>>
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