Marlow 1.5 tech brief SUBBED NEW SH-March10 Table Final€¦ · Dyneema® SK78 and SK99 to Vectran...
1
Brought to you in association with 36 SEAHORSE has carved a niche for itself as the ultimate performance core material. • DM20 has slightly lower tenacity than SK78, but has one major advantage in that it exhibits virtually zero creep. Used mainly for static load applications such as standing rigging. Another area of confusion can be heat-setting and pre- stretching. Every Marlow D12 Dyneema ® core is pre-stretched to reduce ‘bedding-in’ elongation, limit the amount of elastic elongation and improve rope strength. Pre-stretching involves the application of heat during the process and is sometimes known as heat-setting, although simply applying heat does not have the same effect. Marlow have now been pre-stretching Dyneema ® cores for over 25 years and that experience means we know exactly how to improve a rope’s performance without compromising flexibility or damaging the fibre. Marlow’s MAX Technology takes pre-stretching to a new level by using a precisely controlled process to take Dyneema ® to the limits of heat and load during the Pre- Stretching process – it could be called ‘Super Pre-Stretching’. D12 MAX ropes were introduced to offer the ultimate in strength realisation from Dyneema ® and to virtually eliminate elastic and ‘bedding-in’ elongation. D12 MAX ropes are stronger size for size than standard D12 – the MAX process packs more Dyneema ® into the same diameter, hence the extra strength. However, D12 MAX ropes are stiffer and harder than the standard pre-stretched D12 ropes. The graphs ( opposite) show the relative elongation of Dyneema ® SK78 and SK99 to Vectran and Zylon. When elongation is measured as a % of break load (Fig. 2, middle ), it is shown that while PBO offers the lowest elongation followed by Dyneema ® in D12 MAX and then D12, there is no differential between SK78 and SK99. However, when elongation is measured at a given load (for example, 4,000kg), which is more relevant to specifying rope for onboard applications (Fig. 1, top), the advantages of SK99 over SK78 in terms of elongation are clear. This is because the rope is working at a lower percentage of its break load. Dyneema ® exhibits creep, and it is important to understand how this affects a rope’s elongation characteristics. Creep can often have a negative effect on a rope’s performance and strength, when ropes are subjected to high loads for extended periods. The extension over time graph (Fig. 3, bottom) shows how Dyneema ® ropes behave over a period of time. • Initial loading will result in elastic extension. This is immediate upon loading and is immediately recoverable upon release of the load (elastic contraction). • After the elastic extension of the initial loading the rope will experience what is known as viscoelastic extension. This is further extension over time and is fairly limited. Unlike elastic stretch, viscoelastic stretch will only recover slowly over time once the load is released. • Finally there is creep, which is permanent, non-recoverable and time dependent. Creep occurs at the yarn molecular level when the rope is under constant load. • Once the load is released and elastic and viscoelastic extension recovered the rope will ultimately have experienced an element of permanent extension. This is a factor of both creep and ‘bedding in’, which is when individual fibre components in the rope and/or splice settle into their preferred position when under load. Marlow lead the market in performance yachting rope technology. Our Grand Prix Series offers performance benefits and a competitive edge… and is specified by winners! Jon Mitchell, Managing Director www.marlowropes.com q SEAHORSE 37 The demands on high-performance running rigging are becoming higher and Marlow’s Grand Prix Series offers core options using Dyneema ® , Vectran and Zylon (PBO). Each has its own strengths and weaknesses, but Dyneema ® has become the ‘Gold Standard’ for performance running rigging. Dyneema ® is a HMPE (High Modulus Polyethylene), also known as UHMWPE or Ultra High Molecular Weight Polyethylene and is available in a number of different grades. All grades of Dyneema ® have excellent fatigue resistance (cyclic bending) and UV, chemical and abrasion resistance, but all have poor heat resistance due to a relatively low melting point (150°C). Dyneema ® offers the best strength-to-weight ratio of any material used in rope manufacture, rivalled only by PBO, and is now the material of choice for high-performance cores. Marlow offer a range of Dyneema ® cores to suit application preferences as well as budget. However, with new grades of Dyneema ® being introduced and different treatments available, the decision as to which core is best can often be confusing. • SK75 – for many years the strongest Dyneema ® grade and the standard material that everybody understands. Thanks to new and improved grades, SK75 is being used less and less and is now not offered by Marlow. • SK78 – has become the standard grade used by Marlow and other reputable manufacturers. SK78 has the same strength as SK75 but offers significantly improved creep characteristics than its predecessor. • SK90 – launched in 2009 and offers approximately 10-15% strength improvement over SK75/8. However, SK90 only has the same elongation and creep characteristics as SK75. While still available, SK90 is now not specified by Marlow ropes due to the introduction of… • SK99 – the latest offering from DSM Dyneema ® launched in 2013. SK99 has 20% strength advantage over SK78 and crucially retains the same elongation and creep characteristics as SK78 – outgunning SK90 on all levels! SK99 has an unmatched strength-to-weight ratio and Technical Brief Holding on Why the latest Dyneema ® products are better than ever... To be involved in the Technical Brief advertorial column please contact – [email protected] 0 10 20 30 40 50 60 70 80 90 100 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 Load (% of ABL) Elongation (%) Load/Extension (%/%) D12 SK99 D12 MAX SK99 V12 (Vectran) Z12 (HM PBO) 0 10 20 30 40 50 60 70 80 90 100 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 Load (% of ABL) Elongation (%) Load/Extension (%/%) D12 SK99 D12 MAX SK99 V12 (Vectran) Z12 (HM PBO) 0 2000 4000 6000 8000 10000 12000 14000 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 Load (kg) Elongation (%) Load Extention of 9mm cores (%/kg) D12 SK78 D12 SK99 D12 MAX SK78 D12 MAX SK99 V12 (Vectran) Z12 (HM PBO) 0 2000 4000 6000 8000 10000 12000 14000 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 Load (kg) Elongation (%) Load Extention of 9mm cores (%/kg) D12 SK78 D12 SK99 D12 MAX SK78 D12 MAX SK99 V12 (Vectran) Z12 (HM PBO) Extension (%) Time Extension over time SK75 SK78 SK99 Viscoelastic Contraction Permenent Extension Elastic Contraction Elastic Extension Viscoelastic Extension Extension due to Creep Extension over time Load/Extension (%/%) Load Extension of 9mm cores (%/kg) D12 99/78 D12 MAX 99/78 V12 (Vectran) Z12 (HM PBO)
Transcript of Marlow 1.5 tech brief SUBBED NEW SH-March10 Table Final€¦ · Dyneema® SK78 and SK99 to Vectran...
Brought to you in association with
36 SEAHORSE
has carved a niche for itself as the ultimate performancecore material.
• DM20 has slightly lower tenacity than SK78, but has onemajor advantage in that it exhibits virtually zero creep. Usedmainly for static load applications such as standing rigging.Another area of confusion can be heat-setting and pre-
stretching. Every Marlow D12 Dyneema® core is pre-stretchedto reduce ‘bedding-in’ elongation, limit the amount of elasticelongation and improve rope strength. Pre-stretching involvesthe application of heat during the process and is sometimesknown as heat-setting, although simply applying heat does nothave the same effect. Marlow have now been pre-stretchingDyneema® cores for over 25 years and that experience meanswe know exactly how to improve a rope’s performance withoutcompromising flexibility or damaging the fibre.
Marlow’s MAX Technology takes pre-stretching to a newlevel by using a precisely controlled process to takeDyneema® to the limits of heat and load during the Pre-Stretching process – it could be called ‘Super Pre-Stretching’.D12 MAX ropes were introduced to offer the ultimate instrength realisation from Dyneema® and to virtually eliminateelastic and ‘bedding-in’ elongation.
D12 MAX ropes are stronger size for size than standardD12 – the MAX process packs more Dyneema® into the samediameter, hence the extra strength. However, D12 MAX ropes are stiffer and harder than the standard pre-stretchedD12 ropes.
The graphs (opposite) show the relative elongation ofDyneema® SK78 and SK99 to Vectran and Zylon.
When elongation is measured as a % of break load (Fig. 2,middle), it is shown that while PBO offers the lowestelongation followed by Dyneema® in D12 MAX and then D12,there is no differential between SK78 and SK99.
However, when elongation is measured at a given load (for
example, 4,000kg), which is more relevant tospecifying rope for onboard applications (Fig. 1, top), the advantages of SK99 overSK78 in terms of elongation are clear. This isbecause the rope is working at a lowerpercentage of its break load.
Dyneema® exhibits creep, and it is important tounderstand how this affects a rope’s elongationcharacteristics. Creep can often have a negative effect on arope’s performance and strength, when ropes are subjected tohigh loads for extended periods. The extension over timegraph (Fig. 3, bottom) shows how Dyneema® ropes behaveover a period of time. • Initial loading will result in elastic extension. This is
immediate upon loading and is immediately recoverableupon release of the load (elastic contraction).
• After the elastic extension of the initial loading the rope willexperience what is known as viscoelastic extension. This isfurther extension over time and is fairly limited. Unlikeelastic stretch, viscoelastic stretch will only recover slowlyover time once the load is released.
• Finally there is creep, which is permanent, non-recoverableand time dependent. Creep occurs at the yarn molecularlevel when the rope is under constant load.
• Once the load is released and elastic and viscoelasticextension recovered the rope wil l ult imately haveexperienced an element of permanent extension. This is afactor of both creep and ‘bedding in’, which is whenindividual fibre components in the rope and/or splice settleinto their preferred position when under load.Marlow lead the market in performance yachting rope
technology. Our Grand Prix Series offers performance benefitsand a competitive edge… and is specified by winners!Jon Mitchell, Managing Director www.marlowropes.com q
SEAHORSE 37
The demands on high-performance running rigging arebecoming higher and Marlow’s Grand Prix Series offers coreoptions using Dyneema®, Vectran and Zylon (PBO). Each hasits own strengths and weaknesses, but Dyneema® hasbecome the ‘Gold Standard’ for performance running rigging.
Dyneema® is a HMPE (High Modulus Polyethylene), alsoknown as UHMWPE or Ultra High Molecular WeightPolyethylene and is available in a number of different grades.All grades of Dyneema® have excellent fatigue resistance(cyclic bending) and UV, chemical and abrasion resistance,but all have poor heat resistance due to a relatively lowmelting point (150°C).
Dyneema® offers the best strength-to-weight ratio of anymaterial used in rope manufacture, rivalled only by PBO, and isnow the material of choice for high-performance cores. Marlowoffer a range of Dyneema® cores to suit applicationpreferences as well as budget. However, with new grades ofDyneema® being introduced and different treatments available,the decision as to which core is best can often be confusing. • SK75 – for many years the strongest Dyneema® grade and
the standard material that everybody understands. Thanksto new and improved grades, SK75 is being used less andless and is now not offered by Marlow.
• SK78 – has become the standard grade used by Marlowand other reputable manufacturers. SK78 has the samestrength as SK75 but offers significantly improved creepcharacteristics than its predecessor.
• SK90 – launched in 2009 and offers approximately 10-15% strength improvement over SK75/8. However,SK90 only has the same elongation and creepcharacteristics as SK75. While still available, SK90 is nownot specified by Marlow ropes due to the introduction of…
• SK99 – the latest offering from DSM Dyneema® launchedin 2013. SK99 has 20% strength advantage over SK78and crucially retains the same elongation and creepcharacteristics as SK78 – outgunning SK90 on all levels!SK99 has an unmatched strength-to-weight ratio and
Technical
Brief
Holding onWhy the latest Dyneema® products are better than ever...
To be involved in the Technical Brief advertorial column please contact – [email protected]
0
10
20
30
40
50
60
70
80
90
100
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5
Load
(% o
f AB
L)
Elongation (%)
Load/Extension (%/%)
D12 SK99
D12 MAX SK99
V12 (Vectran)
Z12 (HM PBO)
0
10
20
30
40
50
60
70
80
90
100
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5
Load
(% o
f AB
L)
Elongation (%)
Load/Extension (%/%)
D12 SK99
D12 MAX SK99
V12 (Vectran)
Z12 (HM PBO)
0
2000
4000
6000
8000
10000
12000
14000
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5
Load
(kg)
Elongation (%)
Load Extention of 9mm cores (%/kg)
D12 SK78
D12 SK99
D12 MAX SK78
D12 MAX SK99
V12 (Vectran)
Z12 (HM PBO)
0
2000
4000
6000
8000
10000
12000
14000
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5
Load
(kg)
Elongation (%)
Load Extention of 9mm cores (%/kg)
D12 SK78
D12 SK99
D12 MAX SK78
D12 MAX SK99
V12 (Vectran)
Z12 (HM PBO)
Exte
nsio
n (%
)
Time
Extension over time
SK75 SK78 SK99
Viscoelastic Contraction
Permenent Extension
Elastic Contraction
Elastic Extension
Viscoelastic Extension
Extension due to Creep
Extension over time
Load/Extension (%/%)
Load Extension of 9mm cores (%/kg)
D12 99/78
D12 MAX 99/78
V12 (Vectran)
Z12 (HM PBO)
![Vectran | Engineering Data by · PDF fileENGINEERING DATA VECTRAN TECH.FNL[FINAL]-QXD 10/26/99 10:13 AM Page 2 Grasp The World OfOf Tomorrow Grasp The World Tomorrow ENGINEERING DATA](https://static.fdocuments.us/doc/165x107/5a9e5a7d7f8b9a0d7f8d946b/vectran-engineering-data-by-data-vectran-techfnlfinal-qxd-102699-1013-am.jpg)
