AbstractInnovative tensile, creep, fatigue, environmental weathering and ageing test methods have been developed to compare the ultimate and relative performances of four commercial brands of non-metallic continuous multi fibre strength member yarns, and one jointed non-metallic multi fibre strength member yam. The main materials under investigation were two commercial brands of the para aramid polymer yarn polyparaphenylene terepthalate, also investigated were ultra high molecular weight polyethylene (UHMWPE) and E glass.
Assessment of the materials has been made in the light of current theories on the mechanical and chemical performance. Comparisons are made between the properties of jointed aramid yarn and virgin yarn material. A comparison of the tensile and creep performances of aramid in laboratory yarn tests and with fully manufactured communication cables containing the same aramid material is made.
The results of the investigations indicate a very similar performance of different aramid brands in all areas. The aramid materials proved to be the best all round non-metallic peripheral strength members. UHMWPE offered good ageing and abrasion resistance but exhibited a high creep rate. E glass suffered greatly from the effects of mechanical abrasion but possessed the lowest creep rate of all the materials tested.
The tensile performance of a finished cable type was analysed in terms of composite axial moduli resulting from aramid and central GRP rod contributions. The creep rate and performance of a finished cable type was found to be the same as that accepted for the constituent strength member yarn indicating an absence of undesirable mechanical changes such as core gripping. Jointed aramid is shown to offer the same tensile and creep performance benefits as virgin aramid but in fatigue tests the joints pulled apart indicating unsuitability of the type of joint used for aerial applications. Aramid was found to be the most suitable material for use as a non-metallic strength member in aerial, internal, duct and direct buried applications.
|Date of Award||Jan 1995|