Avoiding crack nucleation and propagation during upset bulging of tubes

As an alternative to joining by fusion welding, joining by upset bulging (JUB) can be applied in cases where tubes are joined to plates, sheet metal, or other tubes and profiles. If a tube is joined to a pierced flat plate, joining is accomplished by creating bulges in the tube by axial compression, which enclose and securely lock the plate. The JUB process has a large potential for reducing cycle times, realizing joints between different materials and for increasing the dimensional accuracy of the joints compared to fusion welding. The joints produced by this forming technique are free from the negative impact of heat affected zones on the material properties. However, the material undergoes large plastic deformation during the JUB process. When the bulges are fully compressed, local damage and failure can be observed which reduce the service life properties of the joints. This paper presents an experimental and numerical study of the damage evolution and crack initiation in mechanical joining by upset bulging. Experiments were carried out to analyse the occurrence of failure. The results are supported by FE analyses. Nucleation of cracks strongly depends on the final bulge height and consequently on the degree of deformation on the inner side of bulges. Tensile tests show that cracks in the bulge reduce the strength of the joint to half of the undamaged material. A new bulge design with a modified shape is presented, which reduces the damaging effect of the upset bulging process and thus improves the strength of the joints.     

The rate of growth in scientific publication and the decline in coverage provided by Science Citation Index

The growth rate of scientific publication has been studied from 1907 to 2007 using available data from a number of literature databases, including Science Citation Index (SCI) and Social Sciences Citation Index (SSCI). Traditional scientific publishing, that is publication in peer-reviewed journals, is still increasing although there are big differences between fields. There are no indications that the growth rate has decreased in the last 50 years. At the same time publication using new channels, for example conference proceedings, open archives and home pages, is growing fast. The growth rate for SCI up to 2007 is smaller than for comparable databases. This means that SCI was covering a decreasing part of the traditional scientific literature. There are also clear indications that the coverage by SCI is especially low in some of the scientific areas with the highest growth rate, including computer science and engineering sciences. The role of conference proceedings, open access archives and publications published on the net is increasing, especially in scientific fields with high growth rates, but this has only partially been reflected in the databases. The new publication channels challenge the use of the big databases in measurements of scientific productivity or output and of the growth rate of science. Because of the declining coverage and this challenge it is problematic that SCI has been used and is used as the dominant source for science indicators based on publication and citation numbers. The limited data available for social sciences show that the growth rate in SSCI was remarkably low and indicate that the coverage by SSCI was declining over time. National Science Indicators from Thomson Reuters is based solely on SCI, SSCI and Arts and Humanities Citation Index (AHCI). Therefore the declining coverage of the citation databases problematizes the use of this source.     

Influence of lighting conditions on the appearance of typical interior materials

Two studies investigated how lighting influences perception of various materials. Experiment 1 focused on preferences of cold or warm light. Participants' task was to indicate preference for either coolish or warmish light for 20 different materials. The selection included materials typically used for wall or floor of interior spaces. Different hues and surface characteristics were present. Specifically two materials of blue color (cold hue) were preferred in a cold light while red carpet (warm hue) and synthetic turf materials were preferred in warm light. This latter choice was explained by automatic reference of synthetic turf to the appearance of natural grass. There were no clear light source preferences for other materials. Experiment 2 explored how the same 20 materials are evaluated under LED lighting in comparison to three other lighting situations (halogen lamp, high‐intensity discharge lamp, and compact fluorescent lamp). The results of this explorative study were not conclusive. The materials chosen for this experiment differed greatly in their structure and optical properties. In conclusion, light influence on the evaluation of materials needs systematic investigation in future research. © 2013 Wiley Periodicals, Inc. Col Res Appl, 40, 50–61, 2015     

An end-to-end tool chain for Sensory Experience based on MPEG-V

This paper provides an overview of our research conducted in the area of Sensory Experience including our implementations using MPEG-V Part 3 entitled “Sensory Information”. MPEG-V Part 3 introduces Sensory Experience as a tool to increase the Quality of Experience by annotating traditional multimedia data with sensory effects. These sensory effects are rendered on special devices like fans, vibration chairs, ambient lights, scent disposers, water sprayers, or heating/cooling devices stimulating senses beyond the traditional ones. The paper's main focus is on the end-to-end aspects including the generation, transmission, and synchronized rendering of sensory effects with the traditional multimedia data taking movie clips as an example. Therefore, we present in this paper an open source tool chain that provides a complete end-to-end sensory effect generation and consumption framework. Furthermore, we summarize results from various subjective quality assessments conducted in this area. Finally, we point out research challenges that may encourage further research within this emerging domain.     

Front dynamics in catalytic surface reactions

A variety of pattern formation phenomena in catalytic surface reactions can be attributed to the dynamics of interfaces, or fronts, separating distinct uniform states. The states may represent surface coverages by different adsorbates or in the case of forced oscillations, different phases of oscillation. The dynamics of fronts are strongly affected by front instabilities and by diffusion anisotropy. We identify two new pattern formation mechanisms associated with different front behaviors in orthogonal directions: an ordering process by which stationary labyrinths in an isotropic system evolve into ordered stationary stripes, and confinement of isotropic spatiotemporal chaos to one space dimension, a state we term stratified chaos.     

Probabilistic analysis of pipelines with corrosion defects by using FITNET FFS procedure

A probabilistic method based on the corrosion module of the FITNET FFS procedure is presented to perform the structural integrity analysis for pipelines. The comparison of the failure pressure determined by both deterministic and probabilistic methods shows that even for a high safety factor, the deterministic method may predict nonconservative results. FITNET FFS procedure predicts a similar probability to that given by the Shell-92 model. The sensitivity analysis of both the uncertainty of the variables and the underlying model shows that the corrosion depth has the most significant contribution to the pipeline failure at an inspection interval of 8 years.     

State space modeling of non-proportional passive damping in machine tools

In the context of virtual development processes of mechatronic systems like machine tools, the preventive assessment of the effects of lightweight structural components on the characteristics of controlled feed systems and therefore on the power and energy requirement of machine tools is of great importance. The modeling of the damping is often limited in practical computation of real machine tools, because they are mostly limited to proportional damping characteristics. Yet the presence of discrete dampers, as for instance, in damping units in guides, or known diverse material damping in construction (components made of glass or carbon fiber-reinforced plastic), demands that the possibility of observance of non-proportional damping, in regard to later model updating, has to be given. The article demonstrates the theoretical state-space modeling of non-proportional damped mechanics using the example of a biaxial vertical lathe.