| 1. |
- Vallhagen, Johan, 1965, et al.
(författare)
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Robustness in aerospace components manufacturing and fabrication – a case study
- 2011
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Ingår i: Proceedings of ISABE2011.
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Konferensbidrag (refereegranskat)abstract
- One approach to light weight designs of jet engine components is to fabricate structures instead of making large complex castings. This needs other methodology to design, plan and verify the joining processes and geometry dimensioning and tolerancing of the parts. This case study has used methods and tools for robust design developed for use in the automotive industry. The purpose of the study was to evaluate the methodology on jet engine components.With virtual geometry models, assembly modeling can be done based on locating schemes, describing the kinematics relations of the assembly. The effect of locator disturbances and part error on critical assembly dimensions can be analyzed with respect to three-dimensional effects. The locating schemes have also been evaluated through a measuring process analyzing the repeatability.The conclusion is that the Robust Design and Tolerancing methodology can be applied to the type of fixturing of joining needed for fabrication of parts in the case study and that great improvements can be made optimising the placement of reference points.
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| 2. |
- Edholm, Peter, 1974, et al.
(författare)
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Robust Tolerance Design Applied on Robot Concept Development
- 2010
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Ingår i: 8th International NordDesign Conference, NordDesign 2010; Goteborg; Sweden; 25 August 2010 through 27 August 2010. ; , s. 21-30
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Konferensbidrag (refereegranskat)abstract
- A robust tolerance design concept based on locating schemes (for example, used in the car industry for sheet metal parts) and the methods and tools connected to that concept are applied on a new robot development. A case study of a robot assembly is performed in a new robot development project. The robot is mainly designed using machined parts, and traditionally these parts are toleranced using feature-to-feature based tolerances and linear dimensioning. The goal of this case study is to see if there are any advantages to using a new approach when designing robots to enable high geometric quality at a low cost. With limitations, the study shows that it seems possible to effectively use the tolerance design concept in robot development with assemblies consisting of machined parts.
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| 3. |
- Forslund, Anders, 1982, et al.
(författare)
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MULTIDISCIPLINARY ROBUSTNESS EVALUATIONS OF AERO ENGINE STRUCTURES
- 2011
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Ingår i: XX International Symposium on Air Breathing Engines 2011 (ISABE 2011), Proceedings of a meeting held 12-16 September 2011, Gothenburg, Sweden.
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Konferensbidrag (refereegranskat)abstract
- This paper presents a case study made to investigate the functional robustness of a jet engine turbine frame. Using virtual tools, a multidisciplinary analysis involving eight disciplines is performed on 50 non-nominal geometries. These geometries are obtained by varying the positions of the locators in the locating schemes on some parts of the assembly. Results show that geometrical variation can significantly affect the structural stresses on the product, and should thus be investigated further.
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| 4. |
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| 5. |
- Forslund, Anders, 1982, et al.
(författare)
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Robust lifecycle optimization of turbine components using simulation platforms
- 2012
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Ingår i: Proceedings of the 28th Congress of the International Council of the Aeronautical Sciences, ICAS 2012. - 9781622767540 ; 4, s. 2593-2604
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Konferensbidrag (refereegranskat)abstract
- n early phases of turbofan engine component design, simulation is favored since it reduces the need for expensive physical testing. However, deterministic simulations for model validation do not consider uncertainty at all. Uncertainties can be classified into three types: aleatory uncertainties, epistemic uncertainties, and error. In this paper, we investigate the potential of a multidisciplinary simulation platform to address these uncertainties and errors for a given test case. We place specific focus on the geometry assurance of a given turbofan component - the Turbine Rear Structure (TRS). Simulations are generally performed based on nominal geometries, materials and loads. However, when a product is mass-produced, each realization of the product design will deviate from the nominal geometry. By generating CAD models from scanned 3D-data of manufactured parts and running them through the simulation platform, the effect that geometric variation has on aerodynamic and structural performance can be investigated. Further, by moving the reference points in a virtual assembly process, we can, to some extent, suppress the effects that this variation has on aerodynamic and structural performance. From a technical point of view, the suggested approach means a significantly improved ability to numerically simulate and optimize robustness of component designs with functionality criteria from principally different disciplines. From an industrial application point of view, the suggested approach provides a tool for including part variation in the early design face, rather than being treated downstream in the development process.
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| 6. |
- Forslund, Anders, 1982, et al.
(författare)
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Virtual Robustness Evaluation of Turbine Structure Assemblies Using 3D Scanner Data
- 2011
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Ingår i: Proceedings of the ASME 2011 International Mechanical Engineering Congress & Exposition. - 9780791854877 ; 1, s. 157-165
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Konferensbidrag (refereegranskat)abstract
- In this paper, the functional robustness of a jet engine component is investigated. Located at the rear part of the engine, the Turbine Rear Structure (TRS) provides a support structure for the low-pressure shaft, while redirecting the exhaust flow from the low-pressure turbine to the exit nozzle. For larger engines, TRSs are fabricated assemblies consisting of cast, wrought and sheet metal parts.In a case study, virtual tools are used to examine how geometrical variation in cast parts of the TRS assembly affects performance. Variation data are obtained by scanning cast parts in a 3D laser scanner. The resulting data are fed into a CAD model as surface point parameters. The parts are then assembled virtually using CAT software. The assemblies are subsequently fed into a simulation platform where they are meshed, and CFD and FEM are used to evaluate the structural and aerodynamic effects of the variation.To quantitatively analyze the effects of variation, five cast parts with different geometrical variations are virtually assembled into 25 geometries and analyzed with respect to sixteen functional properties. Results show that geometric variation has a noticeable effect on performance.We believe this approach to be a useful tool in engine design. Being able to virtually examine the geometrical robustness of a design in early phases reduces the need for redesign loops. This leads not only to faster and less expensive product development, but also to better and more reliable engine designs.
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| 7. |
- Glon, Fanny, et al.
(författare)
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3D SEM for surface topography quantification - A case study on dental surfaces
- 2014
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Ingår i: 14th International Conference on Metrology and Properties of Engineering Surfaces, Met and Props 2013. - Bristol : IOP Publishing. ; 483:1
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- 3D analysis of surface topography is becoming a more used tool for industry and research. New ISO standards are being launched to assist in quantifying engineering surfaces. The traditional optical measuring instrumentation used for 3D surface characterization has been optical interferometers and confocal based instrumentation. However, the resolution here is limited in the lateral dimension to the wavelength of visible light to about 500 nm. The great advantage using the SEM for topography measurements is the high flexibility to zoom from low magnifications and locating interesting areas to high magnification of down to nanometer large surface features within seconds. This paper presents surface characterization of dental implant micro topography. 3D topography data was created from SEM images using commercial photogrammetric software. A coherence scanning interferometer was used for reference measurements to compare with the 3D SEM measurements on relocated areas. As a result of this study, measurements emphasizes that the correlation between the accepted CSI measurements and the new technology represented by photogrammetry based on SEM images for many areal characterization parameters are around or less than 20%. The importance of selecting sampling and parameter sensitivity to varying sampling is high-lighted. Future work includes a broader study of limitations of the photogrammetry technique on certified micro-geometries and more application surfaces at different scales.
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| 8. |
- Lagerberg, Johan W., et al.
(författare)
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Evaluation of the quality of blood components obtained after automated separation of whole blood by a new multiunit processor
- 2013
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Ingår i: Transfusion. - : Wiley. - 0041-1132 .- 1537-2995. ; 53:8, s. 1798-1807
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The Reveos system (Terumo BCT) is a fully automated device able to process four whole blood (WB) units simultaneously into a plasma unit, a red blood cell (RBC) unit, and an interim platelet (PLT) unit (IPU). Multiple IPUs can be pooled to form a transfusable PLT product. The aim of our study was to evaluate the quality of components made with the Reveos system from either fresh (2-8hr) or overnight-held WB. STUDY DESIGN AND METHODS: A prototype of the Reveos system was used to process WB. RBCs were resuspended in SAGM, leukoreduced, and assayed for in vitro quality variables during a 42-day storage period at 2 to 6 degrees C. Twenty-four-hour in vivo recovery was determined on Day42. Plasma was assayed for cellular contamination and activation variables. IPUs were pooled with SSP+ additive solution for in vitro quality assessments during a 7-day storage period at room temperature. RESULTS: Reveos-produced RBCs and plasma units met the predefined requirements. RBC recovery was superior to control units. On Day42, hemolysis was below 0.8% and in vivo recovery was above 75% for all RBCs. Cellular contamination was lower for Reveos-produced plasma. PLT yield was higher with overnight-stored WB. PLT quality was well maintained during storage with no significant differences between the two groups. Conclusion: Blood components prepared with the Reveos from fresh or overnight-held WB meet quality criteria without any relevant difference between the two groups. The Reveos system has the potential to increase efficacy and standardization of blood component preparation.
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| 9. |
- Lööf, Johan, 1979, et al.
(författare)
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Discrete tolerance allocation for product families
- 2012
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Ingår i: Engineering Optimization. - 1029-0273 .- 0305-215X. ; 44:1, s. 75-85
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Tidskriftsartikel (refereegranskat)abstract
- This article extends earlier research on the discrete tolerance allocation problem in order to optimize an entire product family simultaneously. This methodology enables a top-down tolerancing approach where requirements at assembly level on products within a family are allocated to single part requirements. The proposed solution has been implemented as an interface with an optimization algorithm coupled with variation simulation software. The article also consists of an extensive review on the discrete tolerance allocation problem which motivates the extension of the discrete tolerance allocation problem. The suggested approach has been applied to a robot family consisting of two variants with the same requirements at product level.
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| 10. |
- Lööf, Jasmine, 1982-, et al.
(författare)
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Impact of PINCH expression on survival in colorectal cancer patients
- 2011
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Ingår i: BMC CANCER. - : BioMed Central. - 1471-2407. ; 11:103
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Tidskriftsartikel (refereegranskat)abstract
- Background: The adaptor protein PINCH is overexpressed in the stroma of several types of cancer, and is an independent prognostic marker in colorectal cancer. In this study we further investigate the relationship of PINCH and survival regarding the response to chemotherapy in colorectal cancer. Results: Paraffin-embedded tissue sections from 251 primary adenocarcinomas, 149 samples of adjacent normal mucosa, 57 samples of distant normal mucosa and 75 lymph node metastases were used for immunohistochemical staining. Stromal staining for PINCH increased from normal mucosa to primary tumour to metastasis. Strong staining in adjacent normal mucosa was related to worse survival independently of sex, age, tumour location, differentiation and stage (p = 0.044, HR, 1.60, 95% Cl, 1.01-2.52). PINCH staining at the invasive margin tended to be related to survival (p = 0.051). In poorly differentiated tumours PINCH staining at the invasive margin was related to survival independently of sex, age and stage (p = 0.013, HR, 1.90, 95% Cl, 1.14-3.16), while in better differentiated tumours it was not. In patients with weak staining, adjuvant chemotherapy was related to survival (p = 0.010, 0.013 and 0.013 in entire tumour area, invasive margin and inner tumour area, respectively), but not in patients with strong staining. However, in the multivariate analysis no such relationship was seen. Conclusions: PINCH staining in normal adjacent mucosa was related to survival. Further, PINCH staining at the tumour invasive margin was related to survival in poorly differentiated tumours but not in better differentiated tumours, indicating that the impact of PINCH on prognosis was dependent on differentiation status.
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