The creep behaviour of braided cordages made of different high performance fibres, such as ultra high molecular weight extended chain polyethylene (Spectra and Dyneema), liquid crystalline polymer (Vectran) and high tenacity nylon has been studied and then compared both during loading and relaxation phases. Nylon and Vectran appear to have superior creep behaviour to that of Dyneema and Spectra. The heat setting has been found to improve the creep behaviour of nylon cordages. 4.1 The total elongation of unheat-set nylon-66 cordage under load of 32 % of specified breaking strength is higher (13.3 %) after 5 days of loading as compared to that in all other cordages (8.6 % for heat-set nylon-66 cordage, 6.2 % for Dyneema cordage, 6.9 % for Spectra and 3.06 % for Vectran cordage) for equivalent load; however, the rate of recovery and the total recovery of nylon-66 cordage is significantly better than Dyneema and Spectra cordages. The un-recovered length or permanent set observed after 24 h relaxation in nylon cordage is -25 % as compared to 70 % in Dyneema cordage, cordage and 51 % in. Vectran in Spectra cordage. After 13 days, the recovery in nylon cordage is nearly complete while in Dyneema it is -31 % after 5 days and in Spectra and Vectran it is -15 % and -70 % respectively after 25 days. Based on recovered per cent length after removal of load, nylon is superior to all the cordages followed by Vectran. Heat setting of nylon cordage reduces its total elongation from 13.3% to 8.6% at load of 32% of the specified BS. Further, the rate of recovery increases after heat setting the nylon cordage. In first 28 h after removal of load, the recovery for unheat-set and heat-set nylon cordages is 74% and 91% respectively. However, the recovery is nearly complete for both unheat-set and heat-set nylon cordages after extended time period, i.e. ,13 days in this case. In general, the residual breaking strength of Dyneema and Spectra cordages improve after creep at 32% of breaking load i.e. loading and relaxation, while the breaking strength of both unheat-set and heat-set nylon cordages and Vectran' cordage reduces after creep.
Creep behaviour of braided cordages made of high performance fibres for aerospace applications
Kriechverhalten von aus Hochleistungsfasern erzeugten, geflochtenen Seilen für Raumfahrtanwendungen
Indian Journal of Fibre and Textile Research ; 32 , 1 ; 13-20
2007
8 Seiten, 1 Bild, 8 Tabellen, 3 Quellen
Article (Journal)
English
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