| 1. |
- Berglund, Johan C, 1978, et al.
(författare)
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Measuring strategies for smooth tool steel surfaces
- 2008
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Ingår i: Proceedings. - Aachen : Shaker Verlag. - 1610-4773. - 9783832269128 - 3832269126 ; , s. 110-119
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Comparisons between different measuring strategies were made on three types of smooth tool steel surfaces. Three replica materials were tested to study possibilities within replication techniques. An optical interferometer as well as a mechanical stylus was used to evaluate the surfaces. The results showed that the tested replica materials generated good representations of both the form and the surface roughness (Sq > 300 nm). The evaluated surfaces were quite homogeneous, thus, few measurements are needed to get representative results. However, it was found that caution must be taken regarding manually polished surfaces which can be less homogenous and therefore require more measurements to get representative results.
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| 2. |
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| 3. |
- Godhe, Anna, 1967, et al.
(författare)
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Seascape analysis reveals regional gene flow patterns among populations of a marine planktonic diatom
- 2013
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Ingår i: Proceedings of the Royal Society of London. Biological Sciences. - : The Royal Society. - 0962-8452 .- 1471-2954. ; 280:1773
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Tidskriftsartikel (refereegranskat)abstract
- We investigated the gene flow of the common marine diatom, Skeletonema marinoi, in Scandinavian waters and tested the null hypothesis of panmixia. Sediment samples were collected from the Danish Straits, Kattegat and Skagerrak. Individual strains were established from germinated resting stages. A total of 350 individuals were genotyped by eight microsatellite markers. Conventional F-statistics showed significant differentiation between the samples. We therefore investigated whether the genetic structure could be explained using genetic models based on isolation by distance (IBD) or by oceanographic connectivity. Patterns of oceanographic circulation are seasonally dependent and therefore we estimated how well local oceanographic connectivity explains gene flow month by month. We found no significant relationship between genetic differentiation and geographical distance. Instead, the genetic structure of this dominant marine primary producer is best explained by local oceanographic connectivity promoting gene flow in a primarily south to north direction throughout the year. Oceanographic data were consistent with the significant FST values between several pairs of samples. Because even a small amount of genetic exchange prevents the accumulation of genetic differences in F-statistics, we hypothesize that local retention at each sample site, possibly as resting stages, is an important component in explaining the observed genetic structure.
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| 4. |
- Joffrin, E., et al.
(författare)
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Overview of the JET preparation for deuterium-tritium operation with the ITER like-wall
- 2019
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 59:11
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Forskningsöversikt (refereegranskat)abstract
- For the past several years, the JET scientific programme (Pamela et al 2007 Fusion Eng. Des. 82 590) has been engaged in a multi-campaign effort, including experiments in D, H and T, leading up to 2020 and the first experiments with 50%/50% D-T mixtures since 1997 and the first ever D-T plasmas with the ITER mix of plasma-facing component materials. For this purpose, a concerted physics and technology programme was launched with a view to prepare the D-T campaign (DTE2). This paper addresses the key elements developed by the JET programme directly contributing to the D-T preparation. This intense preparation includes the review of the physics basis for the D-T operational scenarios, including the fusion power predictions through first principle and integrated modelling, and the impact of isotopes in the operation and physics of D-T plasmas (thermal and particle transport, high confinement mode (H-mode) access, Be and W erosion, fuel recovery, etc). This effort also requires improving several aspects of plasma operation for DTE2, such as real time control schemes, heat load control, disruption avoidance and a mitigation system (including the installation of a new shattered pellet injector), novel ion cyclotron resonance heating schemes (such as the three-ions scheme), new diagnostics (neutron camera and spectrometer, active Alfven eigenmode antennas, neutral gauges, radiation hard imaging systems...) and the calibration of the JET neutron diagnostics at 14 MeV for accurate fusion power measurement. The active preparation of JET for the 2020 D-T campaign provides an incomparable source of information and a basis for the future D-T operation of ITER, and it is also foreseen that a large number of key physics issues will be addressed in support of burning plasmas.
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| 5. |
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| 6. |
- Jonsson, Per, 1952, et al.
(författare)
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Comparison of whole-body vibration exposures in buses: effects and interactions of bus and seat design
- 2015
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Ingår i: Ergonomics. - : Informa UK Limited. - 0014-0139 .- 1366-5847. ; 58:7, s. 1133-1142
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Tidskriftsartikel (refereegranskat)abstract
- © 2014 Taylor & Francis Bus and seat design may be important for the drivers' whole-body vibration (WBV). WBV exposures in buses during actual operation were assessed. WBV attenuation performance between an air-suspension seat and a static pedestal seat in low-floor buses was compared; there were no differences in WBV attenuation between the seats. Air-suspension seat performance in a high-floor and low-floor bus was compared. Relative to the pedestal seat with its relatively static, limited travel seat suspension, the air-suspension seat with its dynamic, longer travel suspension provided little additional benefit. Relative to the measurement collected at the bus floor, the air-suspension seat amplified the WBV exposures in the high-floor bus. All WBV exposures were below European Union (EU) daily exposure action values. The EU Vibration Directive only allows the predominant axis of vibration exposure to be evaluated but a tri-axial vector sum exposure may be more representative of the actual health risks.
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| 7. |
- Jonsson, Per, 1981, et al.
(författare)
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Cutting AHSS materials in the non normal direction of the sheet material
- 2008
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Ingår i: Proceedings of 2nd Swedish Production Symposium. ; , s. 77-83
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Konferensbidrag (refereegranskat)abstract
- The properties of cutting AHSS (Advance High Strength Steel) materials in the non normal direction of the sheet material are investigated both trough semi industrial testing and FE simulations. Cutting angles of 25°, 35°, 45° and 60° with a clearance of 4%, 8%, 12% and 16% are evaluated. Cast iron to wrought steel are tested against sheet materials ranging from HSS (High Strength Steel) to UHSS (Ultra High strength steel). Two versions of the geometry on the lower cutting edge have been tested, a traditional geometry and a 1,5mm shelf geometry. Side force measurements indicate that for the traditional cutting edge geometry on the lower die, the side force increases with an increased angle. For the shelf geometry this side force is reduced, especially for the higher angles. Simulated results correlate well to the test results. The shelf geometry also reduces the sharpness off the cut edge profile compared to the traditional geometry. During a few tests, fracture wear and chipping occurred on the upper cutting edge, successful actions were made to decrease the risk for fracture wear.
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| 8. |
- Jonsson, Per, 1981, et al.
(författare)
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Laser hardened trimming tools : wear test and geometry evaluation
- 2008
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Ingår i: Proceedings of the IDDRG 2008 Conference. - Olofström : Industriellt utvecklingscentrum i Olofström AB. - 9789163329487 ; , s. 639-650
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Konferensbidrag (refereegranskat)abstract
- The higher product requirements (reduced weight, increased safety, lower emissions…) have meant that a larger number of car body parts must be made in advanced high strength steels. With a reduced lifecycle of a car model from 7 to 5 years this leads to a need for reducing the manufacturing cost and lead time for the tool and die design and manufacturing. The main purpose of this investigation is to establish cost- and lead-time reducing guidelines for selection of tool concepts (choice of die materials, hardening methods and geometry) for different production volume scenarios with respect to sheet materials quality (MS-UHSS) and thickness, without increased die maintenance costs. In this study the cutting edge geometry has been evaluated in respect to the cutting edge radius and the angle of the upper tool. Experimental testing together with FE simulation has been used. Results show that an angle of 93° on the upper cutting edge initially can reduce the cutting work by 14%. Results also shows that by using a cutting edge radius of 80µm, the tool “wear in phase” can be more controlled. Wear test up to 150 000 strokes have been made to evaluate different tool concepts using laser hardened cast iron, cast steel and wrought steel as die material. Sheet material tested was 220RP, DP600, DP800, 700MC and DP1000, with a thickness of t=2mm. The result leads to recommendations for industrial verification. Results among other recommendations are: laser hardened EN-JS-2070 up to 500 000 parts against 220RP and Sleipner up to 1 500 000 parts against 1000DP.
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| 9. |
- Jonsson, Per, 1981
(författare)
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Sheet metal trimming dies – characterisation methods of geometry and surface topography and the influence on wear
- 2010
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In recent years, the life cycle of car models has decreased from 7 to 5 years and the volume sizes are becoming shorter in the automotive industry. The increasing number of car models introduced to the market means that a fewer number of parts must pay the costs for the tool/die design and manufacturing. In consequence, there is a need for reducing the manufacturing cost and lead time for the tool and die manufacturing. The higher product requirements (reduced weight, increased safety and lower emissions) have meant that a larger number of car body parts must be made in AHSS (Advanced High Strength Steels). This has led to a significantly larger abrasive and fatigue tool wear. The tool wear is therefore expected to increase even more in the future, if the issue is not addressed properly. Today the total maintenance cost of the trimming tools are approximately 70% of the total die maintenance cost in a press shop.The purpose of this thesis is to increase the knowledge of how surface topography and geometry on trimming dies influences tool wear, tool life and part quality. Methods to analyze wear, measure cutting edge radius on production dies and methods to analyze surface topography have been established.The cutting edge geometry has been evaluated with respect to the cutting edge radius and the angle of the upper tool. Experimental testing together with FE simulation has been used. Results show that by using a cutting edge radius of 80µm, rather than 20µm, the tool “wear in phase” can be more controlled.Sheet metal trimming when cutting at high angles (25° - 60°) has been evaluated. Two versions of the geometry on the lower cutting edge was tested, a traditional geometry and a 1.5mm shelf geometry. Results show that the shelf geometry reduces side force, especially for the higher angles. The shelf geometry also reduces the sharpness off the cut edge profile, thus increasing part quality, compared to the traditional geometry.Surfaces on both semi-industrial test dies and dies used in production were analyzed with different surface topography analysis methods. The result shows that the wear process is different on the different sides of the trimming edge. The texture direction of the surface is changed due to wear, with the strongest change on the clearance side of the edge. The roughness on sheet side of the edge is reduced due to a hammering effect from the sheet material. The result on the semiindustrial test dies and the production dies correlates well.Future research will be continued on surface topography and trimming edge geometry and its relationship to used manufacturing methods and tool wear.
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| 10. |
- Jonsson, Per, 1981, et al.
(författare)
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Surface Topography on trimming dies and the influence of wear
- 2010
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Ingår i: Proceedings of the International Deep Drawing Research Group. - 9783851251081 ; , s. 345-354
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Konferensbidrag (refereegranskat)abstract
- In this paper it is investigated how surface topography on trimming dies influences the wear process. Surfaces on both semi-industrial test dies and dies used in production were analyzed with different surface topography analysis methods. The result shows that the wear process is different on the different sides of the trimming edge. The texture direction of the surface is changed due to wear, with the strongest change on the clearance side of the edge. The roughness on sheet side of the edge is reduced due to a hammering effect from the sheet material. The result on the test dies and the production dies correlates well.
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