| 1. |
- Andersson, Alf, et al.
(författare)
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Failure Analysis With a New Tool Geometry, X-Die, in Areas With High Tension/Compression Strains
- 2007
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Ingår i: MATERIALS PROCESSING AND DESIGN; Modeling, Simulation and Applications; NUMIFORM '07; Proceedings of the 9th International Conference on Numerical Methods in Industrial Forming Processes (AIP Conference Proceedings). - : AIP. - 1551-7616 .- 0094-243X. - 9780735404151 ; 908, s. 1445-1450
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Konferensbidrag (refereegranskat)abstract
- Sheet-metal forming involves a complex strain distribution over the part. The strains consist of tension, compression, and a mix of both. A geometry has been developed, the X-Die, in order to gain insight into the strain behavior of different materials. The X-Die enables strain paths far into the tension/compression region, thus creating the possibility to extend the experimental base both for definition and for further extrapolation of the Forming Limit Curve (FLC) in the tension/compression region, as well as to evaluate FE-simulation results for the same region.Today, evaluation of cracks is made by using FLC. In the conventional test methods, the strains only reach 40% compression (true strain) and often much lower percentages. In conventional test methods, the FLC for any region beyond these levels is extrapolated from existing data.The experimental test proposed in this work consists of a geometry, the X-die, which has shown that rates of 70% tension/compression can be reached (point 0.7/−0.7 in the FLC). Thereby, the region for prediction of cracks on the compression side can be extended in the Forming Limit Diagram (FLD). Furthermore, the strain paths are easy to follow and the limits when cracks appear can be evaluated. Furthermore, the experimental results show that the behavior depends on the material quality. Qualities such as Extreme High Strength Steel (EHSS) and Aluminum have a limited tension/compression rate due to failure in plane strain tension. Material qualities with high r-values, e.g. Mild steel and High Strength Steel (HSS), reach high tension/compression rates before failure and have regions with clearly defined strain signatures. This will be favorable for comparison with numerical simulations, especially for strain signatures in the tension/compression region. Furthermore, the experiments did not indicate any limitation in the compression region besides the one defined in the normal procedure in creation of an FLC.This geometry is favorable to calibrate simulation results, in order to analyze prediction of strains located on the left side in an FLD. ©2007 American Institute of Physics
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| 2. |
- Odenberger, Eva-Lis, et al.
(författare)
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A short lead time methodology for design, compensation and manufacturing of deep drawing tools for Inconel 718
- 2008
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Ingår i: Conference Best in Class Stamping, June 16 - 18, 2008, Olofström, Sweden. - Olofström : Industriellt utvecklingscentrum i Olofström AB. - 9789163329487
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Konferensbidrag (refereegranskat)abstract
- This paper presents a systematic methodology for the design and manufacturing of deep drawing tools generating high quality components at an extremely short lead time. Prototype tools for five different super alloy Inconel 718 sheet metal components were designed, manufactured and tested in 15 weeks. Two of these prototype tools (A, B) are the topics of this paper. The methodology is based on virtual tool design in which the tool concepts are secured and optimized with respect to sheet metal formability and shape deviation using FE-analyses. Tool surfaces are compensated for springback, if necessary, using the *INTERFACE_COMPENSATED_NEW capability in LS-DYNA v971 (B).The compensated FE tool surfaces are used as reference to generate high quality surfaces suitable for the milling process. Laser scanning was used to determine shape deviation. The CAD-evaluation revealed a minor shape deviation within tolerance of component (A) and a small over-compensation of the final geometry of component (B). The maximum shape deviation was however in the order of the sheet thickness. The work presented in this paper substantiate the idea that it is possible to realize development projects for new applications in Inconel 718 accurately, which is of outmost importance when developing tools at a short lead time. The key is consistent studies according to the systematic methodology in which FEanalyses were used for the virtual tool design and compensation.
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| 3. |
- Odenberger, Eva-Lis, et al.
(författare)
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Thermo-mechanical sheet metal forming of aero engine components in Ti-6Al-4V : Part 1: Material characterisation
- 2013
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Ingår i: International Journal of Material Forming. - : Springer Science and Business Media LLC. - 1960-6206 .- 1960-6214. ; 6:3, s. 391-402
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Tidskriftsartikel (refereegranskat)abstract
- Ti-6Al-4V is one of the most frequently used titanium alloy in aerospace applications such as for load carrying engine structures, due to their high strength to weight ratio in combination with favourable creep resistance at moderate operating temperatures. In the virtual development process of designing suitable thermo-mechanical forming processes for titanium sheet metal components in aero engine applications numerical finite element (FE) simulations are desirable to perform. The benefit is related to the ability of securing forming concepts with respect to shape deviation, thinning and strain localisation. The reliability of the numerical simulations depends on both models and methods used as well as on the accuracy and applicability of the material input data. The material model and related property data need to be consistent with the conditions of the material in the studied thermo-mechanical forming process. In the present work a set of material tests are performed on Ti-6Al-4V at temperatures ranging from room temperature up to 560°C. The purpose is to study the mechanical properties of the specific batch of alloy but foremost to identify necessary material model requirements and generate experimental reference data for model calibration in order to perform FE-analyses of sheet metal forming at elevated temperatures in Ti-6Al-4V.
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| 4. |
- Odenberger, Eva-Lis, et al.
(författare)
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Tool development based on modelling and simulation of hot sheet metal forming of Ti-6Al-4 V titanium alloy
- 2011
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Ingår i: Journal of Materials Processing Technology. - : Elsevier BV. - 0924-0136 .- 1873-4774. ; 211:8, s. 1324-1335
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Tidskriftsartikel (refereegranskat)abstract
- In the aero engine industry alternative manufacturing processes for load carrying aero engine structures imply fabrication. The concept of fabrication involves simple forgings, sheet metals and small ingots of e.g. titanium alloys which are welded together and heat treated. In the concept phase of the product development process, accurate evaluations of candidate manufacturing processes with short lead times are crucial. In the design of sheet metal forming processes, the manual die try out of deep drawing tools is traditionally a time consuming, expensive and inexact process. The present work investigates the possibility to design hot forming tools, with acceptable accuracy at short lead times and with minimal need for the costly die try out, using finite element (FE) analyses of hot sheet metal forming in the titanium alloy Ti-6Al-4 V. A rather straightforward and inexpensive approach of material modelling and methods for material characterisation are chosen, suitable for early evaluations in the concept phase. Numerical predictions of punch force, draw-in and shape deviation are compared with data from separate forming experiments performed at moderately elevated temperatures. The computed responses show promising agreement with experimental measurements and the predicted shape deviation is within the sheet thickness when applying an anisotropic yield criterion. Solutions for the hot forming tool concept regarding heating and regulation, insulation, blank holding and tool material selection are evaluated within the present work.
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| 5. |
- Skåre, T, et al.
(författare)
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Monitoring of friction processes by the means of acoustic emission measurements—deep drawing of sheet metal
- 1998
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Ingår i: Journal of Materials Processing Technology. - 0924-0136. ; 80-81, s. 263-272
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Tidskriftsartikel (refereegranskat)abstract
- Acoustic emission generated in deep drawing processes gives information about the friction and the forming processes between tool and workpiece. This information can be used to supervise or improve the forming process. Measurements of acoustic emission in manufacturing machines in production lines shows that different events such as, galling, tool wear, lubricating failure, different viscosity of lubricants, stick-slip, necking and cracking of the sheet metal can be separated in time- and frequency domain. Laboratory tests show that proportionality exists between the effective output of the friction surfaces and the measured effective output of the AE-sensor in drawing a sheet metal between flat dies. The measured acoustic emission has been influenced by the smoothness, lubricants, relative speeds between the friction surfaces, the contact pressure between the surfaces, galling, changed geometry's of friction surfaces and different types of material in contact. In a forming process will different lubricants result in different lubricity and the measured effective output of the AE-sensor result in a ranking method. The proportionality between the effective output of the friction surfaces and the measured effective output of the AE-sensor established in the laboratory tests has been applied in measurements of acoustic emission in manufacturing machines in production lines. By monitoring the acoustic emission in manufacturing machines, we are able to detect different events, i.e. galling, cracks, toolwear.
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