| 1. |
- Vedantha Krishna, Amogh, 1990-, et al.
(författare)
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Potential approach towards effective topography characterization of 316L stainless steel components produced by selective laser melting process
- 2018
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Ingår i: European Society for Precision Engineering and Nanotechnology, Conference Proceedings - 18th International Conference and Exhibition, EUSPEN 2018. - Bedford : euspen. - 9780995775121 - 0995775125 ; , s. 259-260
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Konferensbidrag (refereegranskat)abstract
- In this paper, an attempt is made to explain the surface texture of Selective Laser Melting (SLM) parts more satisfyingly than the existing methods. Investigations were carried out on the 316L stainless steel SLM samples. To account for most of the surface conditions, a truncheon artefact was employed for the analysis. A Stylus Profilometer was employed as a metrology tool for obtaining the 3D surface measurements. A methodology is proposed to extract and characterize the topographic features of Additive Manufactured (AM) surfaces. Here, the overall roughness of the surface is segregated into the roughness of the powder particles and the waviness due to thermal and the "staircase" effects. Analyzing these features individually results in an increased understanding of the AM process and an opportunity to optimize machine settings.
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| 2. |
- Dimkovski, Zlate, et al.
(författare)
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Complementing 3D Roughness Parameters for Monitoring of Improved Honing of Cylinder Bores
- 2008
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Ingår i: Proceedings of the Swedish Production Symposium (SPS) - 2008. - 9783939026952
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Konferensbidrag (refereegranskat)abstract
- It is of common interest to reduce the oil consumption and frictional losses in the internal combustion engines which are in a great deal influenced by the quality of the cylinder liner surface. Its criss-cross patterned topography consists of a communicating system of grooves of different density, width, and depth, somewhere covered by folded metal, and somewhere totally interrupted and unbalanced as a result of the honing process imperfections. These features are crucial for a good liner’s function and are inspected from scanning electron microscope images by experts, which is subjective and time consuming process. Today, a fast automatic quality control is possible by using optical instruments to measure the liner’s topography, and a computer to calculate and check if the standard roughness and groove parameters are in tolerance. Therefore, combining the profile and image analysis, algorithms were developed to compute liner’s groove parameters from 3D interference measurements taken from three different types of cylinder bore surfaces of passenger cars. One of the surface types was a result of a test of an improved honing and the other two being currently in use. Then, the standard and new parameters (groove interruption, number of grooves, holes, etc) were incorporated in a characterisation tool to objectively and quickly evaluate the improvement of the liner’s quality for an updated monitoring in production.
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| 3. |
- Berglund, Johan C, 1978, et al.
(författare)
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A Method for Visualization of Surface Texture Anisotropy in Different Scales of Observation
- 2011
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Ingår i: Scanning. - : John Wiley & Sons. - 0161-0457 .- 1932-8745. ; 33:5, s. 325-331
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Tidskriftsartikel (refereegranskat)abstract
- Anisotropy of functional surfaces can in many practical cases significantly influence the surface function. Tribological contacts in sheet forming and engine applications are good examples. This article introduces and exemplifies a method for visualization of anisotropy. In a single graph, surface texture properties related to the anisotropy as a function of scale are plotted. The anisotropy graph can be used to explain anisotropy properties of a studied surface such as texture direction and texture strength at different scales of observation. Examples of milled steel surfaces and a textured steel sheet surface are presented to support the proposed methodology. Different aspects of the studied surfaces could clearly be seen at different scales. Future steps to improve filtering techniques and an introduction of length-scale analysis are discussed.
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| 4. |
- Dimkovski, Zlate, 1974-, et al.
(författare)
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Towards 3D Characterisation of Cylinder Liner Surfaces
- 2008
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Ingår i: Proceedings / XII. International Colloquium on Surfaces January 28th and 29th, 2008, Chemnitz, Germany = XII. Internationales Oberflächenkolloquium. - Aachen : Shaker Verlag. - 9783832269128 ; , s. 15-24
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Konferensbidrag (refereegranskat)abstract
- Cylinder liner surface has a direct impact on the oil consumption and frictional losses in the internal combustion engines which are in common interest to be as lower as possible. Thus, the optimisation of the liner surface, its function and manufacture is often on the agenda of the automotive industry. Since the liner surface finish is a subject of improving, there is a need of improving and facilitating of its 3D characterisation preliminary when the parameter control limits are unknown, as well as later when it is experimentally verified and the limits are better determined. For that purpose a method for quality control in 3D of cylinder liners is proposed here. A tool was developed and implemented for rating of cylinder liner surfaces, computing of 3D groove parameters (groove width, height and distance between grooves) and determination of a needed number of measurements.
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| 5. |
- Malmberg, Donald, et al.
(författare)
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Microwave Technology in Steel and Metal Industry, an Overview
- 2007
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Ingår i: ISIJ International. - Tokyo : Nippon Tekko Kyokai. - 0915-1559 .- 1347-5460. ; 47:4, s. 533-538
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Tidskriftsartikel (refereegranskat)abstract
- In many metallurgical operations, effective analysis of the processes can be very difficult with available technology. This is especially true if the analysis is to be performed on-line and in a harsh environment characterized by high temperatures, dust and liquid metal. Protection of the equipment requires both rugged encapsulation as well as elaborate sampling systems and exposure of the equipment to the hazardous environment must be minimised. Often this result in an increased level of service and maintenance requirements and, in the worst case, the maintenance cost might be so high that the equipment is not installed. Microwave technology is a versatile and powerful tool with many different applications in the scientific community. It is insensitive to dust and fume and, for several years, the technology has been tested at MEFOS and evaluated for different metallurgical processes. It has been applied to slag thickness measurement and slag composition in an induction furnace, 3D imaging of the burden surface in a charging model on pilot scale as well as raceway depth measurements in a Blast Furnace. The idea of using microwave technology for gas analysis in metallurgical processes has also been explored. However, despite its many advantages, microwave technology is still not employed extensively in the steel and metal industries. Copyright © 2007 ISIJ.
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| 6. |
- Rosen, Bengt-Göran, 1962, et al.
(författare)
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Topographic modelling of haptic properties of tissue products
- 2014
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Ingår i: Journal of Physics: Conference Series. - Bristol : IOP Publishing. - 1742-6588 .- 1742-6596. ; 483:1
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Konferensbidrag (refereegranskat)abstract
- The way a product or material feels when touched, haptics, has been shown to be a property that plays an important role when consumers determine the quality of products For tissue products in constant touch with the skin, softness becomes a primary quality parameter. In the present work, the relationship between topography and the feeling of the surface has been investigated for commercial tissues with varying degree of texture from the low textured crepe tissue to the highly textured embossed- and air-dried tissue products. A trained sensory panel at was used to grade perceived haptic «roughness». The technique used to characterize the topography was Digital light projection (DLP) technique, By the use of multivariate statistics, strong correlations between perceived roughness and topography were found with predictability of above 90 percent even though highly textured products were included. Characterization was made using areal ISO 25178-2 topography parameters in combination with non-contacting topography measurement. The best prediction ability was obtained when combining haptic properties with the topography parameters auto-correlation length (Sal), peak material volume (Vmp), core roughness depth (Sk) and the maximum height of the surface (Sz). © Published under licence by IOP Publishing Ltd.
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| 7. |
- Wiklund, Daniel, et al.
(författare)
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Evaluation of surface topography parameters for friction prediction in stamping
- 2004
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Ingår i: Wear. - Amsterdam : Elsevier. - 0043-1648 .- 1873-2577. ; 257:12, s. 1296-1300
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Tidskriftsartikel (refereegranskat)abstract
- The continued globalisation of the automotive industry, leading to increasing demands for competitiveness and escalating legislative requirements, is the main driving force of research activities of steel sheet surfaces. Recent studies on the stamping process have been carried out among others within AUTOsurf, a project funded by the European Community, and by Wihlborg and Crafoord. The purpose of this study was to evaluate the viability of the proposed parameters for friction prediction. Seventeen different surface topographies were investigated. The sheet materials were either, hot-dip galvanised, electrogalvanised or galvannealed, and electron beam or electric discharged textures. The frictional response was measured in a bending under tension (BUT) test under mixed lubricated conditions. This BUT test simulates the conditions of the die radius in a stamping tool. The laboratory test differs from the experimental work performed in AUTOsurf which simulated the conditions of the holding-down plate. In spite of the differences in test equipments in AUTOsurf, e.g. the rotational friction tester (RTF), on a comparison the correlation of frictional response was significant. But neither of the proposed parameters could predict the frictional response with sufficient accuracy in this study. In addition, the friction model in AUTOsurf describes peak lubrication as a dragging phenomenon on sliding surfaces. The movement eased friction in inverse proportion to the average peak area. However, the trend in this study showed the opposite, movement eased friction proportionally to the average peak area. The result indicates a switch of dominant friction mechanism when the sliding velocity is increased, i.e. from a dragging phenomenon at low velocities to micro-hydrodynamic wedge effects at high velocities.
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| 8. |
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| 9. |
- Zheng, Qiye, et al.
(författare)
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High Contrast Thermal Conductivity Change in Ni-Mn-In Heusler Alloys near Room Temperature
- 2019
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Ingår i: Advanced Engineering Materials. - Weinheim : Wiley-VCH Verlagsgesellschaft. - 1438-1656 .- 1527-2648. ; 21:5
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Tidskriftsartikel (refereegranskat)abstract
- Materials with an abrupt transition between a low and a high thermal conductance state at a critical temperature would be useful for thermal regulation applications. Here, the authors report a high contrast reversible thermal conductivity change through the thermally-induced martensitic transition (MT) in Ni-Mn-In alloys. The authors measure the thermal conductivity of a wide temperature range 130 < T < 530 K using time-domain thermoreflectance (TDTR). The thermal conductivity of these alloys increases from ≈7.0-8.5 W m−1 K−1 to ≈11.5-13.0 W m−1 K−1 through the MT near 300 K as temperature rises, with a rate of change among the highest yet reported in solid-state materials with thermally-induced phase transitions. Based on Hall resistivity measurements, the authors further show that the change of thermal conductivity is dominated by the electronic contribution, which results from a unique carrier mobility change through the MT. Their findings highlight the interplay between the structural disorders and the thermal transport in alloys through solid-state phase transitions and open a new avenue in the search of high-performance materials for thermal regulation. © 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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| 10. |
- Ghasemi, Yahya, 1982-, et al.
(författare)
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Effect of water film thickness on the flow in conventional mortars and concrete
- 2019
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Ingår i: Materials and Structures. - Dordrecht : Springer. - 1359-5997 .- 1871-6873. ; 52:3
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Tidskriftsartikel (refereegranskat)abstract
- Mortar and concrete can be divided into two phases of solids and water where water fills the voids between the grains and also coats the surface of particles. The current study investigates the influence of the thickness of coating water on flow spread of mortars and concretes. The article aims at correlating consistency of concretes to consistency of mortars. It was found that the flow behavior of granular mixtures can be directly related to the average water film thickness that envelops the particles. The concept was tested on mortar and concrete mixtures with different cement types, aggregate grading, aggregate shape, fineness and proportioning; proving water film thickness to be the most critical parameter affecting the flow. The results of the study indicate the possibility of predicting the flowability of mixtures by knowing the enveloping water film thickness. In addition, the relation between flowability of mixtures measured in different sizes of slump cone is explored to enable translating flow of mortars measured in mini-slump cone to flow of concrete obtained from Abram’s cone.
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