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This paper aims to investigate the suitability of additive manufacturing to produce O-ring seals.

The O-rings were made by the PolyJet-Matrix technology using four different digital materials and then tested for relaxation properties under static and dynamic (sliding) conditions. The approximation of the relaxation curves involved modelling with a Prony series.

The PolyJet-Matrix technology offers new opportunities to model elastomeric elements, with examples being the O-rings produced and tested for their relaxation properties. Describing the behaviour of the particular materials fabricated with this technology by using relaxation functions will extend the knowledge base on digital materials.

The four types of photopolymers used in the experiment differed in viscoelastic properties. The analysis of the stress relaxation of the O-ring models was performed at four different step displacements of the loading element.

The test results may be useful for the design of O-ring seals made of new elastomeric materials. The relaxation properties of the O-rings made of such materials can be applied to analyse the dynamics of seals, for instance, face seals.

The originality of the work lies in the use of digital materials to design and produce elastomeric elements with different relaxation properties, which was confirmed by the test results. This paper presents results of a relaxation analysis for a ring model and the material that the ring is made of. It also discusses how 3D printing and digital materials can be applied in practice.

ONE of the main connections that rubber has with the subject of tribology is for O‐ring seals, and in view of the saying that “efficient lubrication is impossible without efficient sealing,” O‐rings are just as important as any other oil seal.

The paper outlines the growth in low friction materials, the various elastomers available and the seal designs which have evolved around the utilisation of these materials.

SELECTING the correct bearing for any particular application involves more than the determination of the correct type and size. It is true that the calculation of the nominal working life will give an indication of the operational life before failure, but this calculation only takes into account the fatigue life of the material. If this theoretical life is to be obtained—and perhaps exceeded—then additional factors must be taken into account when initially designing the bearing arrangement. Lubrication and protection from the operating environment are two very important considerations.

Building automobile bodies from lightweight materials using space‐frame construction techniques is increasingly popular because of exhaust emission legislation. One proposed method of achieving this is by using plug and socket joints, which are injected with adhesive after assembly. A method for controlling this process, irrespective of component tolerances, is proposed here. A test rig representing a plug and socket joint was injected with the adhesive and a method for successfully filling the butt‐jointed end of the joint found. The addition of a restriction to the joint's open end gave a method of filling the cavity without creating any air gaps. The use of neoprene O‐ring seals for creating the restriction was investigated. The pressure of the adhesive at the joint inlet (gate) was recorded (data logger), and an analysis of this has been used to determine the point when adhesive injection can be arrested and the joint correctly filled.

Inspection of simple components can be a demanding task in itself, as the Reflex company found out. Stephen McClelland reports.

DOWTY Equipment Limited began the study of fuel systems for gas turbines in 1944, following the adoption by the de Havilland Engine Company of the Dowty Live Line Pump as the most promising type for conversion to a fuel pump. The resulting co‐operation hd to a widening interest and in 1945 the first design schemes for a complete fuel system were initiated.

This paper aims to research the influence of pressure, friction factors, roughness and actuating speed to the mixed lubrication models of outstroke and instroke.

Mixed lubrication model is solved by finite volume method, which consists of coupled fluid mechanics, deformation mechanics and contact mechanics analyses. The influence of friction factor on the finite element model is also considered. Then, contact pressure, film thickness, friction and leakage have been studied.

It was found that the amount of leakage is sensitive to the film thickness. The larger the film thickness is, the greater the influence received from the friction factor, however, the effect of oil film on the friction is negligible. The friction is determined mainly by the contact pressure. The trend of friction and leakage influenced by actuating velocity and roughness is also obtained.

The influence of friction factor on the finite element model is considered. This can make the calculation more accurate.

A new type of hydrostatic and hydrodynamic non-contacting face seals has been designed to meet the requirements of lower leakage, longer life and more repeatedly start and stop on shaft seals raised by liquid rocket engine turbopumps. And an experimental study on the performance of the face seal in the actual liquid oxygen turbopump was completed where low-viscosity water was selected as the seal fluid for the sake of safety. The paper aims to discuss these issues.

Different performances of face seals under preset conditions were obtained by repeatedly running tests, and the main performance parameters encompass leakage, fluid film pressure between the faces, operating power, face temperature, and so on.

The results indicate that the designed face seal has a smaller amount of leakage, with a minimum value of 3 ml/s. Furthermore, the designed face seal has been proved to demand lower operating power. Since its operating power changes slightly with different sealed fluid pressures, the new seal can be deployed in the harsh working condition with high pressure or with high speed (greater than 20,000 rpm). However, one proviso is that when liquid is employed as the seal fluid, the groove depth should be relatively deeper (greater than 10 μm).

In response to future engineering requirements, study on the controllable spiral-groove face seals to improve the current design is being conducted.

The advancement of such non-contacting face seals proffers important insights to the design of turbo-pump shaft seal in a new generation of liquid rocket engine with regard to the requirement of frequent start and stop as well as long life on it.

This paper gives a review of the finite element techniques (FE) applied in the analysis and design of machine elements; bolts and screws, belts and chains, springs and dampers, brakes, gears, bearings, gaskets and seals are handled. The range of applications of finite elements on these subjects is extremely wide and cannot be presented in a single paper; therefore the aim of this paper is to give FE researchers/users only an encyclopaedic view of the different possibilities that exist today in the various fields mentioned above. An Appendix included at the end of the paper presents a bibliography on finite element applications in the analysis/design of machine elements for 1977‐1997.