Groove design for form fit joints made by electromagnetic pulse crimping

The electromagnetic pulse process can be an alternative for many conventional production processes. It can be used for perforating, cutting, welding, forming and crimping. In this thesis, the latter will be investigated in detail, with the emphasis on tubular joints bearing axial tension and/or torsion loading. To get acquainted with the subject, first a literature study was performed concerning the general principles of electromagnetic pulse crimping. Because a new field shaper had to be designed, literature on this topic was also consulted. Finally, the design and use of grooves in crimp joints was studied. It has been reported that an inner piece (mandrel) with additional grooves in the joining zone significantly increases the strength of a crimped joint [1]. However, the information on electromagnetic pulse crimping with a mandrel with more than one groove is very limited. Therefore one of the main goals of this thesis is to determine an optimal design for a mandrel with two grooves used for axially loaded joints. A combination of finite element simulations and experiments was used to draw preliminary conclusions involving the double groove design. In a later stage torsional joints will be designed and suitable filler materials to realize leak proof joints will be evaluated

Mapping the interview transcript: identifying spatial policy areas from daily working practices

An interview transcript can be a rich source of geographical references whose potential are not always fully realised in their conventional analysis. Geo-referencing techniques can be used to assign a spatial footprint to place names, adding value to these data and allowing the geographic information within them to be exploited when coupled with GIS technology. This paper discusses a method of analysing and visualising interview transcripts in order to understand the spatial extent of public policy practitioners’ activities. Through aggregation and statistical mapping it is possible to gain insight into the importance of space across a range of public policy themes and to understand the relationship between practitioner defined policy themes and the formal administrative boundaries within which they typically work. The research demonstrates that spatial working practices rarely conform to formal administrative boundaries and that there are varying degrees of spatial focus between different policy themes within localities. It also reveals that spatial working practices can be continued to be influenced by historic geographies and can be pulled in different directions reflecting both the devolved nature of the sector and the particular geographical context of the setting. It concludes that mapping the interview transcript can add value and provide additional insights to more conventional analysis

WTC2005-63340 FRICTION AND WEAR OF DIAMOND-LIKE CARBON COATINGS LUBRICATED WITH BIODEGRADABLE OILS

ABSTRACT The tribological behaviour of coated machine components lubricated with a biodegradable saturated ester and unsaturated ester oil has been studied. Different diamond-like carbon-based coatings (DLC) were selected as low friction coatings: pure DLC, Si-doped, Ti-doped and W-doped DLC. The performance of the studied ester oils has been compared with sunflower oil and mineral oil lubrication as reference. The oils were all additivated in the same way with conventional anti-wear (AW) and extreme pressure (EP) additives. Different tests have been performed: disc on disc, ball on disc and block on ring tests give an overview of the influence of different sliding modes. The effect of the lubricant on a coated system compared to the use of the coated system without lubrication is clear for the wear , but less obvious for the friction. It was found that DLC/DLC contacts lubricated with biodegradable lubricants show similar friction as steel/steel contacts. The effect of the different types of base oil is independent of the coating type. Additive activity which was clear in steel/steel contacts was not obvious in DLC/DLC contacts

Plasma polymerization of fluorine alloyed amorphous carbon coatings

This article reports on the deposition conditions and characterization of plasma polymerized fluorocarbon coatings grown by an inductively coupled radio frequency plasma source, using CH4 and CF4as precursor gases. SiH4, H2, or Ar were further added to the plasma to investigate their influence on the coating properties. The coatings were characterized by x-ray photoelectron spectroscopy to determine the surface and bulk composition and combined with Fourier-transform infrared spectroscopy to reveal the structure of the coatings. The mechanical properties (hardness and Young's modulus) were measured by nano-indentation. The surface energy was obtained by contact angle measurements with two different liquids. By varying the deposition conditions, it was possible to adjust separately the polar and dispersive part of the surface energy. With the appropriate feed gases and process parameters, we were able to deposit coatings with surface energies as low as 14 mN/m. A low polar component of the surface energy corresponds to a high fluorine, CF3and CF2content at the surface of the coatings. The maximum contact angle achieved was 113°. By adding H2 to the plasma, it is possible to minimize the polar component and maximize the dispersive component of the surface energy to obtain a relatively hard (3 GPa) coating with a hydrophobic nature [contact angle (H2O) = 90°]. © 1999 American Vacuum Society.status: publishe

Applying educational design research to develop a low-cost, mobile immersive virtual reality serious game teaching safety in secondary vocational education

Students in secondary vocational education often have to learn and practice their skills in potentially dangerous situations, operating complex machinery or working in hazardous conditions. As a consequence, they need to be trained on how to work safely, to respect safety regulations, to wear protective gear and related equipment, to consider ergonomics, and to follow emergency procedures. However, this is difficult in current teaching on hazard perception due to a lack of authentic and real-life learning conditions, and due to learning materials often not being adapted to secondary vocational students. To address these challenges, we adopted an Educational Design Approach in which we designed, developed, and tested a low-cost, mobile immersive virtual reality serious game, teaching hazard perception to secondary vocational students. We engaged 8 teachers and 50 students from 5 secondary vocational schools to co-design and test the prototype serious game. Final test results demonstrate both students and teachers valued the learning experience positively, in terms of spatial presence, involvement, design, interest/enjoyment and value/usefulness. During several iterations, we were also able to identify critical design elements, which were valued positively in terms of both enjoyment and perceived usefulness. The design elements are discussed in a detailed way to support both researchers and practitioners in their future design of immersive virtual reality learning experiences. Finally, directions for future research are presented