Hakan Göçerler, Bernhard Pfeil, Friedrich Franek, Christoph Bauer, Eugenia Niculescu-Morzsa and Stefan Nehrer
The paper aims to focus on the individual contribution of water to the lubrication regimes in articular joints because understanding of these regimes is crucial not only for the…
Abstract
Purpose
The paper aims to focus on the individual contribution of water to the lubrication regimes in articular joints because understanding of these regimes is crucial not only for the treatment of diseases like osteoarthritis but also for the development of new implants to have a longer service cycle.
Design/methodology/approach
Cartilage specimen and the synovial fluid were both isolated from bovine knee joints that are enclosed by a synovial membrane under sterile conditions of a biosafety Level 2 (BSL2) cabinet. Subchondral bone was removed from the cartilage because it not only creates a stable base to place the specimen on the holder, but it also acts as a primary shock absorber protecting the overlaying cartilage under high-impact loads. A specimen holder specially designed for tests and was attached to the linear oscillation (SRV) test machine. The SRV test machine provides a reciprocating sliding motion between the cartilage samples that are submerged into the selected biological media. The entire system can be mounted on the BSL2 cabinet, sealed with the convoluted gaiter and transported to the SRV machine with a specifically designed handle for the entire system. The process ensures sterile conditions for tests on biological samples that are highly sensitive to the environmental conditions.
Findings
A remarkably low coefficient of friction value for distilled water constitutes more evidence to support the assumption of the impact of water in the friction behaviour of the cartilage-against-cartilage contact. As the fluid in articular cartilage (AC) effectively serves as a synovial fluid reserve and 70-80 per cent of its composition is distilled water, it can be stated that the tribotest system mimics the natural working conditions of an actual knee joint adequately.
Research limitations/implications
Time and limited availability of the animal-driven samples led to a focus on certain parameters mentioned in the approach. A planned scan of parameter matrix, such as variation of load and speed, would allow deeper knowledge on the lubrication regimes.
Practical implications
Study of relevant tribological contact in human joints might give ideas on new designs for artificial joints.
Social implications
Understanding of lubrication regimes is crucial not only for the treatment of diseases like osteoarthritis but also for the development of new implants to adapt motion of related joint.
Originality/value
Exclusion of water and application as the primary lubricant in the test system brings a new perspective to joint lubrication.
Details
Keywords
Predrag Dašić, Friedrich Franek, Emilia Assenova and Miroslav Radovanović
Wide tribology concept through the knowledge interaction from physics, chemistry and various engineering disciplines, has put tribology in a group with interdisciplinary sciences…
Abstract
Wide tribology concept through the knowledge interaction from physics, chemistry and various engineering disciplines, has put tribology in a group with interdisciplinary sciences. This work gives information about the international standardization in the field of tribology, International Tribology Council, whose members consist of 36 national tribology society and associations from 34 countries worldwide and an overview of other international and regional organizations and institutions. Analysis of ISO, IEC and EN standards in various fields related to tribology and a view of the structure of most significant ISO Technical Committees related to standardization in tribology fields are presented.
Details
Keywords
Paolo Minetola and Luca Iuliano
– The purpose of this paper is to present a custom-built tribometer that mimics the wear of additive manufactured fixtures used in inspection of sheet metal components.
Abstract
Purpose
The purpose of this paper is to present a custom-built tribometer that mimics the wear of additive manufactured fixtures used in inspection of sheet metal components.
Design/methodology/approach
Referring to the inspection of sheet metal parts, the fixture undergoes sliding wear during loading and unloading phases of the quality control operation. A new wear test is proposed to mimic the actual wearing conditions of the fixtures because the standards are deemed insufficient. In the tribometer, a cylindrical Alumide cantilever beam is made to slide back and forth inside a slightly bigger hole cut into a nickel-plated steel sheet. The sheet is spring loaded such that it applies a force on the specimen. The wear on the beam is measured after every 500 cycles of the beam motion.
Findings
Results of some first test trials are reported to evaluate the durability of Alumide fixtures fabricated by selective laser sintering. The results are also compared to those obtained for a machined fixture made of an Al-Cu alloy.
Practical implications
The proposed wear test estimates the life time of additive manufactured fixtures in terms of numbers of inspected components. The test can be extended to different materials to compare their durability.
Originality/value
Today, the fabrication of custom fixtures by means of additive manufacturing technologies is a reality in many manufacturing industries. The advantage of using those production technologies for custom fixtures is well assessed in literature in terms of manufacturing times and costs, whereas little attention was given to the life time and wear behaviour of fabricated fixtures. For its practical implication, the fixture durability is indeed very important for manufactures.