Wear and Friction Behaviour of Additive Manufactured PEEK under Non-conformal Contact

Tribological properties of laser sintered polyether-ether-ketone (EOS PEEK HP3) were investigated using a rolling-sliding test rig. This investigation aimed to study the wear and friction failure mechanism of EOS PEEK HP3. The main objectives included to conduct wear and friction tests under non-conformal contact, to monitor surface temperature, to carry out surface characterization with microscopy. With this rolling-sliding test rig, tests were carried out on an EOS PEEK HP3 specimen running against a steel disc unlubricated, with various slip-ratios under a contact pressure of 56 MPa, 48 MPa and 39 MPa respectively. Both wear and friction were measured. The results have shown that both friction and wear were increased with an increase of either slip-ratios or the contact pressures, exacerbated by high surface temperatures. It has also been observed that both friction and wear failures were associated with the degradation of the non-conformal contact surfaces due to crystallinity changes that correlated well with working conditions. Using microscopy it was found that such failures as pitting, fatigue and surface cracking were affected by the surfaces in contact, including the degree of melting of the surface. Based on the observation on the contact surfaces, the failure mechanisms of EOS PEEK HP3 include surface melting and contact fatigue failures with the high slip-ratio and the high contact pressure conditions. The findings of this investigation have the potential to help to design & develop additive manufacturing PEEK products. Typically, these results can be used in a design process for a more effective polymeric gear system

Electromechanical reliability of ITO/Ag/ITO multilayer coated pet substrate for optoelectronic application

Successful design and fabricate flexible devices a Low sheet resistance, high optical transmittance, high mechanical reliability and low cost for electrode component are required. Aluminum-doped Zinc Oxide (AZO) film has been extensively used as an alternative promising candidate to Indium tin oxide (ITO) that are the predominant transparent conductive oxide (TCO) film in potential applications such as flexible organic light- emitting diodes, flat-panel displays, solar cells, and thin film transistors (TFTs). However AZO film are too brittle and their resistivity is rather high in some cases compared to ITO, can not completely meet flexible optoelectronic device requirements. In this work, AZO (35 nm)/Ag(12 nm)/AZO (35 nm) films was deposited on polyethylene naphthalate using RF magnetron sputtering system at room temperature. The mechanical behavior of continuous and patterned oxide film were investigated by means bending and twisting tests respectively. The change in the electrical resistance of the AZO/Ag/AZO multilayer was monitored in situ. In addition, failure mechanism of different pattern of AZO/Ag/AZO by using scanning electron microscopy after twisting test was investigated. Finite elements simulations will also be carried out to further understand the failure mechanisms of AZO/Ag/AZO under twisting deformation. In all shapes, cracks are observed to initiate from the pattern edges. Cracking and buckling delimitation failure modes were observed for all samples investigated at critical strains. Furthermore the buckling test demonstrated that the high failure strain of the ductile Ag layer lead to mechanical stability of multilayer compared to the single-layered AZO sample

Stress corrosion of GRP tensile strength members in optical fibre cables

Pultruded glass fibre reinforced plastics (or GRP) rod is being increasingly used in the area of cable design, used for strength members in optical fibre cables. The possibility of failure by the process of stress corrosion has resulted in the need to determine the reliability of the dielectric cables when in service. The viability of life predictions being made from the study of stress corrosion fracture surfaces is investigated. The production of static fatigue data for composite materials is needed to enable any accurate predictions to be made