| 1. |
- Asp, Leif, et al.
(författare)
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An experimental investigation of the influence of delamination growth on the residual strength of impacted laminates
- 2001
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Ingår i: Composites. Part A, Applied science and manufacturing. - 1359-835X .- 1878-5840. ; 32:9, s. 1229-1235
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Tidskriftsartikel (refereegranskat)abstract
- This study concerns an experimental investigation to establish data for validation of residual strength models for impacted composite panels. The work focuses on compression tests of panels with embedded artificial delaminations at various depths. Accompanying tests on undamaged and impact-damaged panels are reported and the relevance of the tests on artificially delaminated panels is assessed. In the experiments both the artificially delaminated and the impacted plates failed by delamination growth. Consequently, the same mechanism governed failure in the two cases. Hence, the artificially delaminated plate test is reliable for validation of methods developed for analysis of the residual strength of impact-damaged panels. However, for impacted plates, the load at global plate buckling was consistently 10% lower than that of the artificially delaminated plates and 20% lower than that of the undamaged plates. Hence, conservative prediction of the global buckling load of an impacted composite panel require s methods that consider influence of stiffness reduction of the damaged zone. © 2001 Elsevier Science Ltd. All rights reserved.
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| 2. |
- Lagerspetz, E., et al.
(författare)
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Pervasive Communities in the Internet of People
- 2018
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Ingår i: 2018 IEEE International Conference on Pervasive Computing and Communications Workshops, PerCom Workshops 2018. - : Institute of Electrical and Electronics Engineers Inc.. - 9781538632277 ; , s. 40-45
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Konferensbidrag (refereegranskat)abstract
- The Internet has traditionally been a device-oriented architecture where devices with IP addresses are first-class citizens, able to serve and consume content or services, and their owners take part in the interaction only through those devices. The Internet of People (IoP) is a recent paradigm where devices become proxies of their users, and can act on their behalf. To realize IoP, new policies and rules for how devices can take actions are required. The role of context information grows as devices act autonomously based on the environment and existing social relationships between their owners. In addition, the social profiles of device owners determine e.g. how altruistic or resourceconserving they are in collaborative computing scenarios. In this paper we focus on community formation in IoP, a prerequisite for enabling collaborative scenarios, and discuss main challenges and propose potential solutions. © 2018 IEEE.
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| 3. |
- Neikter, Magnus, 1988-, et al.
(författare)
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Tensile properties of laser powder bed fusion built JBK-75 austenitic stainless steel
- 2023
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Ingår i: Materials Science & Engineering. - : Elsevier Ltd. - 0921-5093 .- 1873-4936. ; 874
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Tidskriftsartikel (refereegranskat)abstract
- Laser powder bed fusion (PBF-LB) is an additive manufacturing (AM) process that has several advantages to conventional manufacturing, such as near net-shaping capabilities and reduced material wastage. To be able to manufacture a novel material, however, one needs to first optimize the process parameters, to decrease porosity content as low as possible. Therefore, in this work the process parameters of PBF-LB built JBK-75 austenitic stainless steel, and its influence on porosity, microstructure, and hardness have been investigated. The least amount of porosity was found by using 132 W laser power, 750 mm/s scan speed, layer thickness 30 μm, and 0.12 mm hatch distance. These process parameters were then used to manufacture material for tensile testing, to investigate the tensile properties of PBF-LB built JBK-75 and potential anisotropic behavior. Hot isostatic pressing (HIP) was also performed in two sets of samples, to investigate the effect of pore closure on the tensile properties. The ultimate tensile strength (UTS) for the un-HIPed specimens was 1180 (horizontally built) and 1110 (vertically built) MPa. For the HIPed specimens, it was 1160 (horizontally built) and 1100 (vertically built) MPa. The anisotropic presence was explained by the presence of texture, with a multiple of random distribution (MRD) up to 4.34 for the {001} planes, and defects.
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| 4. |
- Singh, A. A., et al.
(författare)
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Green composites : Versatile material for future
- 2017
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Ingår i: Green Biocomposites. - Cham : Springer Verlag. ; , s. 29-44
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Bokkapitel (refereegranskat)abstract
- The growing concern towards environmental problems and the urgent need for more versatile environmental friendly materials has led to increasing attention about polymer composites, i.e. fillers/reinforcing materials coming from renewable sources and biodegradable, especially from forest. The composites usually referred to as “green”, can find several industrial applications as discussed in this chapter. Biodegradable polymers coming from natural resources are also one important constituent of green composites. This chapter provides tactic for readers regarding the materials used for the fabrication and specific application of green composites in various fields. Furthermore, a discussion of the major material attributes of green composites is provided. From these focuses, a series of balancing application properties are explained. The chapter concludes that green composites have potential for use in a number of applications, but as with all design, one must carefully match the material to the application.
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| 5. |
- Stirling, R., et al.
(författare)
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Global survey on durability variation – on the effect of the reference species
- 2016
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Ingår i: Proceedings of the International Research Group Annual Meeting 2016.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Climate change due to anthropogenic emissions is the largest environmental challenge of ourtime. Forest-based value chains play an important role in reducing the accumulation of CO2 in the atmosphere. Maximizing the use of wood to tackle climate change requires improved understanding of the service life of timber products. This information can best be obtained from field testing and while there is an abundance of field performance data from sites all over the world, most of the data are not available in a form that can be utilised for service life models.The IRG Durability Database aims to improve the usability of existing performance data and create added value for durability research and service life prediction. The present paper takes the first steps in comparing global field test performance data from the IRG Durability Database for non-durable reference species. Data were obtained from six species above ground and ground contact field tests from 36 sites around the world. For each dataset, decay rates and service life (where applicable) were calculated. Datasets were then grouped together based on test method and species. Decay rate was faster and more uniform in ground contact than above ground. Inground contact, beech decayed most rapidly, followed by Norway spruce and Scots pines apwood. All appeared to be suitable for use as reference species, however slow-grown spruce should be avoided. There were no statistically significant correlations between ground contact decay rate and the Scheffer Climate Index (SCI). In above ground tests, differences in decay ratewere largely related to differences in moisture dynamics. Species with the greatest absorption and retention of water decayed most rapidly. Test methods that absorbed and retained the most moisture (e.g. painted L-joints) resulted in more rapid decay. Above ground decay rate and SCI were significantly correlated in two data sets that had a wide range of SCI values. Correlations were not significant when only European test sites were included. Estimating decay rate from field testing results in highly variable data. Comparing data from global test sites is made more difficult by the absence of common field testing standards.
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