Vergleichende Untersuchung der Verschleißbilder von Steckverbindern aus Reibverschleiß- und Vibrationsprüfungen mit unterschiedlichen Prüfrichtungen

In this study a comparison between the wear patterns of electrical connectors resulting from two different test types, namely fretting corrosion test and vibration test, is conducted. In both tests, the excitation directions include the mating direction as well as the orthogonal directions corresponding to the mating direction. Different measurement techniques are used to identify similarities and differences between the wear resulting from these test types. The results show fundamentally different critical directions with regard to wear for the respective test types. Furthermore, it is shown that the induced movement of the fretting tests lead to a higher degree of wear than the vibration tests. Also, it is not adequately possible to establish a direct relationship between the induced movement and the excitation amplitude caused by the attached wires since there is a superposition of several movements in the case of real applications.

SOME PARTICULAR ASPECTS OF THE AUTOMOTIVE INDUSTRY CONNECTORS

Electrical connectors are very sensitive parts in an electronic system. The actual meaning of reliability and the problems associated with determining it, are often not right understood. The paper presents some particular aspects of the automotive industry connectors’ i.e. fretting, fretting corrosion prevention, aluminium connections. The performance factors governed by the operating conditions and design-technology factors determined by the manufacturing characteristics of a contact unit were analyzed.

Modularity of total hip prosthesis and its tribological implications

Purpose The study aims to analyze the fretting phenomenon, manifested at the taper junctions of modular total hip prostheses (THP). Modularity of prostheses implies the micro-movement occurrence. Fractures can arise as a result of the fretting cracking of the prostheses components, affecting durability of modular THPs. Fretting corrosion is associated with the decrease in the clinical acceptance of hip modular implants. Design/methodology/approach Starting from the fretting phenomenon influence on modularity, monoblock THPs and prostheses with modular femoral head recovered from some review surgeries were investigated. Modular prostheses have a taper junction femoral head – femoral stem neck. Investigation consisted in the analysis of fretting wear and fretting corrosion, of the femoral heads’ taper and of the femoral stems’ trunnions. Findings The main result was that the micro-movement that provokes the fretting of the femoral head-femoral stem taper junction analyzed does not have the same direction. It is manifesting in the direction of the axis of the femoral head taper, around this axis or as a composed movement. The authors suspect that this is due to the different design of the taper. In this way, the inclination of the stem’s trunnion into the head hole has a different angular misalignment and may cause greater damages of the taper. Originality/value This result can be a starting point from the improvement of the future taper junctions design that will improve the quality, durability and modularity of THPs.

Adverse reaction to metal debris due to fretting corrosion between the acetabular components of modular dual-mobility constructs in total hip replacement: a systematic review and meta-analysis

Modular dual-mobility (MDM) constructs can be used to reduce dislocation rates after total hip replacement (THR). However, there are concerns about adverse reaction to metal debris (ARMD) as a result of fretting corrosion between the metal liner and shell. This systematic review reports outcomes following THR using MDM components. It was registered with PROSPERO and conducted in line with Cochrane and PRISMA recommendations. Sixteen articles were included overall, with meta-analysis performed on relevant subsets using a random intercept logistic regression model. Estimated median incidence of ARMD requiring revision surgery within study follow-up period was 0.3% (95% CI 0.1 – 1.8%, from 11 cohort studies containing 1312 cases). Serum metal ion levels were mildly raised in 7.9% of cases, and significantly raised in 1.8%, but there was no correlation with worse clinical hip function scores within studies. Dislocation rate was 0.8%. Revision rate was 3.3%. There are mixed reports of wear on the backside of the metal liner from the acetabular shell and screw heads. Both implant design and component malseating are implicated, but currently it is unclear to what extent each factor is responsible. Studies were poor quality with high risk of confounding, especially from trunnion corrosion. We have made recommendations for further work. In the meantime, surgeons should be aware of the potential risk of ARMD when considering using an MDM prosthesis, and, if selecting one, must ensure proper seating of the liner and screws intraoperatively. Cite this article: EFORT Open Rev 2021;6:343-353. DOI: 10.1302/2058-5241.6.200146