The fretting fatigue analysis between strands of ACSR
In this paper, self-made fretting fatigue wear test bed was used to investigate fretting fatigue and wear properties of overhead transmission line between the strands, and then the fretting fatigue fracture life and the fracture surface microscopic morphology of ACSR in different testing conditions was analysed. The results show that under larger included angle, larger ACSR tensile force and larger fretting amplitude, the fretting fatigue life of the wire was reduced. The crack initiation and propagation occurs in the contact edge, and the angle is 45° between fracture surface and the wire axis. Fretting fatigue fracture can be divided into three areas: micro-crack nucleation area, fatigue crack propagation area, crack area, and the three regions have different fatigue properties.
Development of controlled heating for fatigue test in overhead conductors at high temperature
The objective of this work was to evaluate the influence of elevated temperature on the fatigue resistance of an all aluminum conductor. A dispositive was developed to reach temperatures like those undergone by high-voltage electrical conductors during their useful life. This dispositive is based on the classical temperature control of proportional integral derivative. In this work, the dispositive used for heating the conductor/suspension clamp assembly and the methodology used to execute fatigue tests at 75 °C of one “All Aluminum Conductor” (Orchid) were presented in detail. There is a remarkable and sensible difference between S and N curves for tests carried out at room temperature and those accomplished at 75 °C, which may indicate degradation of all aluminum conductors when tested under fatigue conditions at higher temperatures.
Submicron polymer structures with X-ray lithography and hot embossing
This article describes the process chain for replication of submicron structures with varying aspect ratios (AR) up to 6 in polymethylmethacrylate (PMMA) by hot embossing to show the capability of the entire LIGA process to fabricate structures with these dimensions. Therefore a 4.7 μm thick layer of MicroChem 950k PMMA A11 resist was spin-coated on a 2.3 μm Ti/TiOx membrane. It was patterned with X-ray lithography at the electron storage ring ANKA (2.5 GeV and λc ≈ 0.4 nm) at a dose of 4 kJ/cm3 using a Si3N4 membrane mask with 2 μm thick gold-absorbers. The samples were developed in GG/BDG and resulted in AR of 6–14. Subsequent nickel plating at 52°C resulted in a 200 μm thick nickel tool of 100 mm diameter, which was used to replicate slit-nozzles and columns in PMMA. Closely packed submicron cavities with AR 6 in the nickel shim were filled to 60% during hot embossing.