| 1. |
|
|
| 2. |
|
|
| 3. |
- DAS, D.K., et al.
(författare)
-
High temperature oxidation behaviour of directionally solidified nickel base superalloy CM–247LC
- 2003
-
Ingår i: Materials Science and Technology. - : Informa UK Limited. - 0267-0836 .- 1743-2847. ; 19:6, s. 695-708
-
Tidskriftsartikel (refereegranskat)abstract
- The present paper describes the isothermal and cyclic oxidation behaviour of the technologically important nickel base directionally solidified superalloy CM-247LC in air in the temperature range 1000-1200°C. This superalloy behaves as a transition nickel base alloy under isothermal oxidation conditions and exhibits a fairly long transient oxidation period (~20 h at 1100°C). Irrespective of the temperature of exposure and nature of oxidation (isothermal or cyclic), a composite oxide scale develops on CM-247LC. While the outer portion of the oxide scale consists of either spinel (NiAl2O4) or a mixture of spinel and NiO, depending on oxidation temperature, the inner portion is always constituted of alumina. Beyond the transient period, the alloy is found to follow parabolic oxidation kinetics. The oxide layer that forms is invariably very non-uniform in thickness, and is dispersed with two types of oxide particles. While tantalum rich oxide particles are found scattered in the outer zone of the oxide layer, hafnium rich oxide particles lie close to the oxide/metal interface. Results also reveal that the nature of oxidation associated with the CM-247LC superalloy causes entrapment of metal islands in the oxide layer.
|
|
| 4. |
|
|
| 5. |
|
|
| 6. |
- Håkansson, Johan, 1974, et al.
(författare)
-
Permeability of felts
- 2000
-
Ingår i: Proc. Nordic Meeting on Materials and Mechanics, Aalborg 2000.
-
Konferensbidrag (refereegranskat)
|
|
| 7. |
|
|
| 8. |
|
|
| 9. |
- Ring-Groth, Margareta, et al.
(författare)
-
Fatigue properties of weldbonded stainless steel joints
- 2000
-
Ingår i: Journal of Advanced Materials. - 1070-9789. ; 32:1, s. 21-27
-
Tidskriftsartikel (refereegranskat)abstract
- Weldbonding of stainless steel with an epoxy adhesive has been investigated with respect to fatigue life. Factors affecting joint strength have been identified and summarized. The weld-bonded joints were mechanically pre-treated, and weld-bonded as flanged single-overlap and cross-tension specimens. The results were compared with spot welded specimens of identical configuration. The weld-bonded specimens have better fatigue properties than spot welded specimens.
|
|
| 10. |
- Carlson, Johan, 1972
(författare)
-
How to Reduce Geometrical Variation in Assembled Products
- 2000
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Vehicle problems, such as wind noise, water leakage and door closing effort are examples of quality and functionality defects that are controlled by the dimensional accuracy of the structural frame of an auto body. The aim of this thesis is towards methods for reducing geometrical variation in assembled products in the automotiv other industries. A general approach to these problems, based on the general idea for how rigidly parts are located in their final position using locating schemes, is developed. In particular, a positioning function which relates locating scheme errors to the corresponding displacement of parts is derived. The positioning function is used to quantify the degree of coupling in a design concept and the geometrical stability provided by a locating scheme. In this way, designers are alerted, during early design phases, to geometrically sensitive and coupled design concepts that are difficult to manufacture and assembly to a proper quality level. However, even for well designed products and assembly processes, the assembly tools such as positioning fixtures may become worn or broken and cause dimensional variation. Fixtures are high precision tools used to position parts for assembly and measurement. The positioning function is combined with methods from multivariate analysis to diagnose fixture errors from routine measurements on parts and products, rather than from special measurements on fixtures. One reason for fixtures being at the centre of interest is that experience from the automotive industry suggests fixture failures as a major reason for dimensional variation in the structural frame of an auto body.
|
|
| 11. |
- Scheffle, M., et al.
(författare)
-
Low cost large area panel processing of MCM-D substrates and packages
- 2001
-
Ingår i: Proceedings of IPACK’01. ; , s. -8
-
Konferensbidrag (refereegranskat)abstract
- The paper describes the results of the EU research project LAP that had the target to develop and to demonstrate a low-cost high-density substrate manufacturing technology for 1st-level die assemblies. The cost target of 1€€/in2 had to be obtained by increasing toady’s 4x4in2 panel sizes to panels upto 24x24in2. The results focus on RF characterization (integrated antennas up to 83GHz, inductors up a Q value of 50), novel packaging strategies (integration of substrate and package), and cost achievements (approaching the cost target). The technology capabilities have been demonstrated with a 9:4 satellite switch operating up to 2.4GHz and readout electronics for physics experiments.
|
|
| 12. |
- Wiklund, Daniel, et al.
(författare)
-
Evaluation of surface topography parameters for friction prediction in stamping
- 2004
-
Ingår i: Wear. - Amsterdam : Elsevier. - 0043-1648 .- 1873-2577. ; 257:12, s. 1296-1300
-
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.
|
|
| 13. |
|
|
| 14. |
|
|
| 15. |
- Albrektsson, Tomas, 1945, et al.
(författare)
-
Les implants oxidés perspectives d’avenir?
- 2003
-
Ingår i: Réalités Cliniques. - 0999-5021. ; 13:4, s. 329-337
-
Tidskriftsartikel (refereegranskat)abstract
- Tous les implants en titane présentent une fine couche adhérente d’oxydes de titane d’environ 5nm. Les techniques d’anodisation
|
|
| 16. |
- Sul, Young-Taeg, 1960, et al.
(författare)
-
Biomechanical Measurements of Calcium-Incorporated Oxidized Implants in Rabbit Bone: Effect of Calcium Surface Chemistry of a Novel Implant
- 2004
-
Ingår i: Clinical Implant Dentistry and Related Research. - 1523-0899. ; 6:2, s. 101-10
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: In oral implantology there has been a general trend away from machine-turned minimally rough and acid-etched and blasted implants toward intermediary roughened surfaces. Mechanical interlocking at micron resolution is claimed to be the dominant reason for the fixation of such implants in bone. However, clinical demands for stronger and faster bone bonding to the implant (eg, in immediately loaded and compromised bone cases) have motivated the development of novel surfaces capable of chemical bonding. PURPOSE: The purpose of the present study is to investigate bone tissue reactions to a newly developed calciumincorporated oxidized implant. The specific aim is to assess the effect of calcium surface chemistry on the bone response. MATERIALS AND METHODS: Calcium (Ca) ion-incorporated implants were prepared by micro arc oxidation methods. Surface oxide properties were characterized by using various surface analytic techniques involving scanning electron microscopy, x-ray diffractometry, x-ray photoelectron spectroscopy, and optical interferometry. Twenty screw-shaped commercially pure (CP) titanium implants (10 turned implants [controls] and 10 Ca-incorporated implants [tests]) were inserted in the femoral condyles of 10 New Zealand White rabbits. RESULTS: After a healing period of 6 weeks, resonance frequency analyses and removal torque measurements of the Ca-incorporated oxidized implants demonstrated statistically significant improvements of implant integration with bone in comparison to machine-turned control implants (p = 0.013 and p = 0.005, respectively). CONCLUSIONS: The Ca-reinforced surface chemistry of the oxidized implants significantly improved bone responses in a rabbit model. The present study suggests that biochemical bonding at the bone-implant interface, in combination with mechanical interlocking, may play a dominant role in the fixation of Ca-incorporated oxidized implants in bone. The observed rapid and strong integration of test Ca implants may have clinical implications for immediate or early loading and improved performance in compromised bone.
|
|
| 17. |
- Sul, Young-Taeg, 1960, et al.
(författare)
-
Bone reactions to oxidized titanium implants with electrochemical anion sulphuric acid and phosphoric acid incorporation.
- 2002
-
Ingår i: Clin Implant Dent Relat Res. - 0905-7161. ; 4:2, s. 78-87
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The importance of the surface properties of implants for a successful osseointegration has been emphasized. It is generally known that bone response to implant surfaces is considerably related to the various surface properties. PURPOSE: The purpose of this study was to investigate bone tissue reactions to multifactorial biocompatibility of the surface oxide of electrochemically oxidized titanium implants. The ultimate objective was to improve surface quality, resulting in enhancement of clinical outcomes of osseointegrated implants. Materials and METHODS: Three different surface types of commercially pure titanium (c.p. Ti) implants were prepared. Turned implants were used for controls and test implants were prepared by the micro arc oxidation (MAO) method, either in sulphuric acid (S implants) or in phosphoric acid (P implants). Implants were inserted in the femur and tibia of 10 mature New Zealand White rabbits. The bone response was evaluated by biomechanical tests, histology, and histomorphometry. The follow-up time was 6 weeks. RESULTS: The mean peak values of the removal torque showed significant differences between control and test S implants (p =.022) but showed no significant differences between control and test P implants (p =.195) or between test S and test P implants (p =.457). In addition, the histomorphometric comparisons of the bone-to-metal contact around entire implants demonstrated 186% increase in S implants (p =.028) and 232% increase in P implants (p =.028) compared with the paired control groups. Quantification of the bone area in the threads did not show any significant differences. CONCLUSIONS: The present results suggest that the primary mode of action in strong bone response to S implants is mechanical interlocking, and to P implants, it is biochemical interaction. It is possible that the phosphate groups in the titanium oxide of P implants provide potential chemical bonding sites for calcium ions and hydroxyapatite of the bone matrix during biologic mineralization. key words: bone responses, histomorphometry, oxidized implants, removal torque test, surface oxide properties
|
|
| 18. |
- Sul, Young-Taeg, 1960, et al.
(författare)
-
Characteristics of the surface oxides on turned and electrochemically oxidized pure titanium implants up to dielectric breakdown: the oxide thickness, micropore configurations, surface roughness, crystal structure and chemical composition.
- 2002
-
Ingår i: Biomaterials. - 0142-9612 .- 1878-5905. ; 23:2, s. 491-501
-
Tidskriftsartikel (refereegranskat)abstract
- Titanium implants have been used widely and successfully for various types of bone-anchored reconstructions. It is believed that properties of oxide films covering titanium implant surfaces are of crucial importance for a successful osseointegration, in particular at compromized bone sites. The aim of the present study is to investigate the surface properties of anodic oxides formed on commercially pure (c.p.) titanium screw implants as well as to study 'native' oxides on turned c.p. titanium implants. Anodic oxides were prepared by galvanostatic mode in CH3COOH up to the high forming voltage of dielectric breakdown and spark formation. The oxide thicknesses, measured with Auger electron spectroscopy (AES), were in the range of about 200-1000 nm. Barrier and porous structures dominated the surface morphology of the anodic film. Quantitative morphometric analyses of the micropore structures were performed using an image analysis system on scanning electron microscopy (SEM) negatives. The pore sizes were
|
|
| 19. |
- Sul, Young-Taeg, 1960, et al.
(författare)
-
Oxidized implants and their influence on the bone response.
- 2001
-
Ingår i: Journal of Materials Science: Materials in Medicine. - 0957-4530. ; 12:10-12, s. 1025-31
-
Tidskriftsartikel (refereegranskat)abstract
- Surface oxide properties are regarded to be of great importance in establishing successful osseointegration of titanium implants. Despite a large number of theoretical questions on the precise role of oxide properties of titanium implants, current knowledge obtained from in vivo studies is lacking. The present study is designed to address two aspects. The first is to verify whether oxide properties of titanium implants indeed influence the in vivo bone tissue responses. The second, is to investigate what oxide properties underline such bone tissue responses. For these purposes, screw-shaped/turned implants have been prepared by electrochemical oxidation methods, resulting in a wide range of oxide properties in terms of: (i) oxide thickness ranging from 200 to 1000 nm, (ii) the surface morphology of barrier and porous oxide film structures, (iii) micro pore configuration - pore sizes<8 microm by length, about 1.27 microm2 to 2.1 microm2 by area and porosity of about 12.7-24.4%, (iv) the crystal structures of amorphous, anatase and mixtures of anatase and rutile type, (v) the chemical compositions of TiO2 and finally, (vi) surface roughness of 0.96-1.03 microm (Sa). These implant oxide properties were divided into test implant samples of Group II, III, IV and V. Control samples (Group I) were turned commercially pure titanium implants. Quantitative bone tissue responses were evaluated biomechanically by resonance frequency analysis (RFA) and removal torque (RT) test. Quantitative histomorphometric analyses and qualitative enzyme histochemical detection of alkaline (ALP) and acidic phosphatase (ACP) activities were investigated on cut and ground sections after six weeks of implant insertion in rabbit tibia. In essence, from the biomechanical and quantitative histomorphometric measurements we concluded that oxide properties of titanium implants, i.e. the oxide thickness, the microporous structure, and the crystallinity significantly influence the bone tissue response. At this stage, however, it is not clear whether oxide properties influence the bone tissue response separately or synergistically. Copyright 2001 Kluwer Academic Publishers
|
|
| 20. |
- Sul, Young-Taeg, 1960, et al.
(författare)
-
Oxidized titanium screws coated with calcium ions and their performance in rabbit bone.
- 2002
-
Ingår i: Int J Oral Maxillofac Implants. - 0882-2786. ; 17:5, s. 625-34
-
Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: The aim was to answer a fundamental question: Do the chemical properties of titanium implants influence osseointegration? MATERIALS AND METHODS: Screw-type implants produced of turned commercially pure (grade 1) titanium (controls) and electrochemically calcium-deposited titanium implants (Ca test implants) were placed in the tibiae and femora of a total of 10 mature New Zealand white rabbits. The macro arc oxidation method was applied for Ca implants. Surface oxides were characterized with different analytic techniques, including x-ray photoelectron spectroscopy, auger electron spectroscopy, scanning electron microscopy, thin-film x-ray diffractometry, and TopScan 3D. The bone response was evaluated by biomechanical tests, histology, and histomorphometry. RESULTS: After a follow-up period of 6 weeks, test Ca implants showed a significant increase in mean peak removal torque (P = .0001) and in the histomorphometric measurement of bone-to-metal contact around the implants (P = .028) in comparison to controls. In addition, more mature mineralized bone was observed adjacent to test Ca implants compared to controls, as evaluated on 10-microm undecalcified, toluidine blue-stained, cut, and ground sections. DISCUSSION: The potential role of surface Ca chemistry to a superior bone response is discussed with specific reference to interaction with Ca(+)-binding proteins and function as binding sites of calcium phosphate mineral. CONCLUSION: The present results suggest that the surface chemical composition of titanium implants is of great importance for the bone response. Ca ion-deposited titanium implants showed fast and strong osseointegration in the rabbit bone model.
|
|
| 21. |
- Sul, Young-Taeg, 1960, et al.
(författare)
-
Qualitative and quantitative observations of bone tissue reactions to anodised implants.
- 2002
-
Ingår i: Biomaterials. - 0142-9612. ; 23:8, s. 1809-17
-
Tidskriftsartikel (refereegranskat)abstract
- Research projects focusing on biomaterials related factors; the bulk implant material, the macro-design of the implant and the microsurface roughness are routinely being conducted at our laboratories. In this study, we have investigated the bone tissue reactions to turned commercially pure (c.p.) titanium implants with various thicknesses of the oxide films after 6 weeks of insertion in rabbit bone. The control c.p. titanium implants had an oxide thickness of 17-200 nm while the test implants revealed an oxide thickness between 600 and 1000 nm. Routine histological investigations of the tissue reactions around the implants and enzyme histochemical detections of alkaline and acid phosphatase activities demonstrated similar findings around both the control and test implants. In general, the histomorphometrical parameters (bone to implant contact and newly formed bone) revealed significant quantitative differences between the control and test implants. The test implants demonstrated a greater bone response histomorphometrically than control implants and the osteoconductivity was more pronounced around the test implant surfaces. The parameters that differed between the implant surfaces, i.e. the oxide thickness, the pore size distribution, the porosity and the crystallinity of the surface oxides may represent factors that have an influence on the histomorphometrical results indicated by a stronger bone tissue response to the test implant surfaces, with an oxide thickness of more than 600 nm.
|
|
| 22. |
- Sul, Young-Taeg, 1960, et al.
(författare)
-
Resonance frequency and removal torque analysis of implants with turned and anodized surface oxides.
- 2002
-
Ingår i: Clin Oral Implants Res. - 0905-7161. ; 13:3, s. 252-9
-
Tidskriftsartikel (refereegranskat)abstract
- The present experimental study was designed to address two issues. The first was to investigate whether oxide properties of titanium implants influenced bone tissue responses after an in vivo implantation time of six weeks. If such a result was found, the second aim was to investigate which oxide properties are involved in such bone tissue responses. Screw-shaped implants with a wide range of oxide properties were prepared by electrochemical oxidation methods, where the oxide thickness varied in the range of 200 nm to 1000 nm. The surface morphology was prepared in two substantially different ways, i.e. barrier and porous oxide film structures. The micropore structure revealed pore sizes of 8 microm in diameter, with a range in opening area from 1.27 microm 2 to 2.1 microm 2. Porosity ranged from 12.7% to 24.4%. The crystal structures of the titanium oxide were amorphous, anatase and a mixture of anatase and rutile type. The chemical compositions consisted mainly of TiO2. Surface roughness ranged from 0.96 microm to 1.03 microm (Sa). Each group of test samples showed its own, defined status with respect to these various parameters. The oxide properties of turned commercially pure titanium implants were used in the control group, which was characterized by an oxide thickness of 17.4 +/- 6.2 nm, amorphous type in crystallinity, TiO2 in chemical composition, and a surface roughness of 0.83 microm (Sa). Bone tissue responses were evaluated by resonance frequency measurements and removal torque tests that were undertaken six weeks after implant insertion in rabbit tibia. Implants that had an oxide thickness of approximately 600, 800 and 1000 nm demonstrated significantly stronger bone responses in the evaluation of removal torque values than did implants that had an oxide thickness of approximately 17 and 200 nm (P < 0.05). However, there were no difference between implants with oxide thicknesses of 17 and 200 nm (P = 0.99). It was concluded that oxide properties of titanium implants, which include oxide thickness, micropore configurations and crystal structures, greatly influence the bone tissue response in the evaluation of removal torque values. However, it is not fully understood whether these oxide properties influence the bone tissue response separately or synergistically.
|
|
| 23. |
- Sul, Young-Taeg, 1960, et al.
(författare)
-
The electrochemical oxide growth behaviour on titanium in acid and alkaline electrolytes.
- 2001
-
Ingår i: Medical Engineering & Physics. - 1350-4533. ; 23:5, s. 329-46
-
Tidskriftsartikel (refereegranskat)abstract
- Titanium implants have a thin oxide surface layer. The properties of this oxide layer may explain the good biocompatibility of titanium implants. Anodic oxidation results in a thickening of the oxide film, with possible improved biocompatability of anodized implants. The aim of the present study was twofold: (1) firstly, to characterize the growth behaviour of galvanostatically prepared anodic oxide films on commercially pure (c.p.) titanium and (2) secondly, to establish a better understanding of the electroche0mical growth behaviour of anodic oxide on commercially pure titanium (ASTM grade 1) after changes of the electrochemical parameters in acetic acid, phosphoric acid, calcium hydroxide, and sodium hydroxide under galvanostatic anodizing mode. The oxide thickness was measured by Ar sputter etching in Auger Electron spectroscopy (AES) and the colours were estimated by an L*a*b* system (lightness, hue and saturation) using a spectrophotometer. In the first part of our study, it was demonstrated that the interference colours were useful to identify the thickness of titanium oxide. It was also found that the anodic forming voltages with slope (dV/dt) in acid electrolytes were higher than in alkaline electrolytes. Each of the used electrolytes demonstrates an intrinsically specific growth constant (nm/V) in the range of 1.4--2.78 nm/V. In the second part of our study we found, as a general trend, that an increase of electrolyte concentration and electrolyte temperature respectively decreases the anodic forming voltage, the anodic forming rate (nm/s) and the current efficiency (nm.cm(2)/C), while an increase of the current density and the surface area ratio of the anode to cathode increase the anodic forming voltage, the anodic forming rate and the current efficiency. The effects of electrolyte concentration, electrolyte temperature, and agitation speed were explained on the basis of the model of the electrical double layer.
|
|
| 24. |
- Sul, Young-Taeg, 1960
(författare)
-
The significance of the surface properties of oxidized titanium to the bone response: special emphasis on potential biochemical bonding of oxidized titanium implant.
- 2003
-
Ingår i: Biomaterials. - 0142-9612. ; 24:22, s. 3893-907
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of the present study is to investigate bone tissue reactions to various surface oxide properties, in particular to different surface oxide chemistry of oxidized titanium implants (grade 1). One control and three test screw-shaped implant groups were prepared. Controls were turned implants. Test implants, i.e. S implants, P implants and Ca implants were by the micro-arc oxidation (MAO) method. The surface characterizations were performed with X-ray photoelectron spectroscopy, Auger electron spectroscopy, scanning electron microscopy, X-ray diffractometry and TopScan 3D. Eighty implants were inserted in the femora and tibiae of ten mature New Zealand white rabbits for 6 weeks. The removal torque values (RTQ) showed significant differences between S implants and controls (p=0.022), Ca implants and controls (p=0.0001), Ca implants and P implants (p=0.005) but did not show significant differences between the others (p>0.05). In addition, the bone to metal contact (BMC) around the entire implants demonstrated 186% increase in S implants, 232% increase in P implants and 272% increase in Ca implants when compared to the paired control groups. Based on the comparative analysis of the surface characteristics resulting different bone responses between all groups, it was concluded that surface chemistry and topography separately or together play important roles in the bone response to the oxidized implants.
|
|
| 25. |
|
|
| 26. |
|
|
| 27. |
|
|
| 28. |
|
|
| 29. |
|
|
| 30. |
|
|
| 31. |
- Lindgren, Mats, et al.
(författare)
-
Application of simulation-based decision making in product development of an RF module
- 2004
-
Ingår i: 5th IEEE conference in Thermal and Mechanical Simulation and Experiments in Micro-Electronics and Micro-Systems. - 0780384202 ; , s. 233-240
-
Konferensbidrag (refereegranskat)abstract
- This paper presents results of simulation-based design evaluation for thermal and thermo-mechanical performance and cost of packaging technology of an RF module for automotive applications. A combination of thermal, thermo-mechanical and cost analysis within the multi-attribute decision making framework enabled design ranking and revealed two MCM-L/D (multi-chip module-laminate/deposition) and MCM-D (deposition) designs with the wire bonding assembly preferred for use in automotive applications for different temperature environments. Simulation-based design guidelines were developed for designing electronic modules exhibiting good thermal and thermo-mechanical performance. By application-based partitioning of the importance weights assigned to the reliability and cost criteria, the guidelines were extended to cover other application areas.
|
|
| 32. |
- Lindgren, Mats, et al.
(författare)
-
Thermal and thermo-mechanical analysis for design evaluation of an automotive radar module
- 2004
-
Ingår i: Quality and Reliability Engineering International. - : Wiley. - 0748-8017 .- 1099-1638. ; 20:7, s. 709-726
-
Tidskriftsartikel (refereegranskat)abstract
- The influence of the substrate technology, assembly method, and housing material on the thermal, thermo-mechanical and cost performance of a radar module for automotive applications has been studied to address the product reliability aspects during the design phase. Flip chip and wire bonding have been evaluated for Multi-Chip Module—Laminate/Deposition (MCM-L/D) and Multi-Chip Module—Deposition (MCM-D) substrate technologies used for electronic packaging solutions in a harsh environment. Solder ball and direct attachment have been investigated as second-level assembly. As a result of thermal and thermo-mechanical simulations and cost analysis, radar module designs combining MCM-D and MCM-L/D with wire bonding have been revealed, which are preferable for use in different temperature environments with respect to two performance criteria, the maximum junction temperature and the manufacturing cost. Simulation-based guidelines have been developed for designing radar modules used in automotive applications while satisfying temperature and stress constraints provided for the module.
|
|
| 33. |
- Rantatalo, Matti, et al.
(författare)
-
Laser doppler vibrometry measurements of a rotating milling machine spindle
- 2004
-
Ingår i: Eighth International Conference on Vibrations in Rotating Machinery. - Bury St Edmunds : Professional Engineering Publishing Ltd. - 1860584470 ; , s. 231-240
-
Konferensbidrag (refereegranskat)abstract
- Finding an optimum process window to avoid vibrations during machining is of great importance; especially when manufacturing parts with high accuracy and/or high productivity demands. In order to make more accurate predictions of the dynamic modal properties of a machining system in use, a non-contact method of measuring vibrations in the rotating spindle is required. Laser Doppler Vibrometry (LDV) is a non-contact method, which is commonly used for vibration measurements. The work presented consists of an investigation into the use of LDV to measure vibrations of a rotating tool in a milling machine, and the effects of speckle noise on measurement quality. The work demonstrates how the axial misalignment and the roundness of a polished shaft can be evaluated from LDV measurements. © IMechE 2004.
|
|
| 34. |
|
|
| 35. |
- Asnafi, Nader, 1960-, et al.
(författare)
-
Laser surface-hardening of dies for cutting, blanking or trimming of uncoated DP600
- 2004
-
Ingår i: Proceedings of the International Conference on Recent Advances in Manufacture and Use of Tools and Dies and Stamping of Steel Sheets. - Olofström : Vovo Cars. ; , s. 193-214
-
Konferensbidrag (refereegranskat)abstract
- In this study, the methods used to harden trim dies were at the focus. Laser surface-hardening was compared to induction- and through-hardening for small and medium-size series production. The sheet materials used were 1.2 mm thick uncoated Docol 600DP and 1.95 mm thick uncoated Docol 600DL The die materials tested were Fermo, Canmo and Sleipner. This investigation showed that the optimum laser-hardening parameters must be established for each trim die material. The trim die in laser-hardened Sleipner exhibits the smallest wear, whilst the trim die in induction-hardened Fermo displays the largest wear in the semi-industrial phase of this study. The magnitude of this largest wear is, however, very small. The trim die in induction-hardened Fermo managed 100 000 strokes without any problem. The dimensional changes after laser hardening are very small. The burr height is very small, regardless of how the trim die is hardened. In this study, two sets of production trim dies were manufactured and set up. This production trim dies are used in the manufacture of V70 B-pillar Left and Right Laser hardening resulted in a lead time reduction by 5 labour days. However, the Tool & Die unit estimates that the lead time reduction obtained with laser hardening should be around 10 days under normal conditions. The cost analysis conducted by the Tool & Die unit shows that the manufacturing costs are reduced by 6%, if laser-hardening is selected. These production trim dies are and will be monitored continuously. As this paper is being written, these dies have been subject to 50 000 strokes.
|
|
| 36. |
|
|
| 37. |
- Andersson, Roger, et al.
(författare)
-
Stainless steel components in automotive vehicles
- 2004
-
Ingår i: Stainless Steel World. - 1383-7184. ; 16:1, s. 34-37
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Components linked to crash safety in automotive vehicles are required to transmit or absorb energy. The energy absorbing capability of a given component depends on a combination of geometry, material properties and loading conditions. Increased crash performance can be obtained by using materials with higher yield strength and relatively high elongation to fracture. These demands have led to increasing interest in the use of high strength stainless steels due to their relatively high elongation to fracture and good formability. To increase knowledge of the formability and forming behaviour of these materials, several components from current and prototype vehicles have been made using high strength stainless steels at Volvo Cars Body Components, Olofstrom, Sweden. These were subsequently analysed in close collaboration with the Division of Manufacturing Systems Engineering at Lulea University of Technology, Sweden.
|
|
| 38. |
- Andersson, Roger, et al.
(författare)
-
The applicability of stainless steels for crash absorbing components
- 2002
-
Ingår i: ACOM : Avesta Sheffield corrosion management and application engineering. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 1101-0681. ; 3-4, s. 7-12
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- To increase crash performance in automotive vehicles it is necessary to use new techniques and materials. Components linked to crash safety should transmit or absorb energy. The energy absorbing capability of a specific component is a combination of geometry and material properties. For these components the chosen material should have high yield strength and relatively high elongation to fracture. These demands have led to increasing interest in the use of high strength stainless steels. The relative performance of three high strength carbon steels and two high strength stainless steel grades was evaluated through intrinsic and simulative tests. The rear bumper for a Volvo Car model in current production was manufactured using the five sheets tested to verify formability and behaviour under load. The bumpers were clamped in a rig that allowed quasi-static impact tests to be made. The energy absorbing capabilities were evaluated by measuring force versus displacement during the impact test.
|
|
| 39. |
- Andersson, Roger, et al.
(författare)
-
Using stainless steel for energy absorbing components in automobiles
- 2001
-
Ingår i: Innovations in processing and manufacturing of sheet materials. - Warrendale, Pa : Minerals, Metals & Materials Society. - 873394909 ; , s. 97-110
-
Konferensbidrag (refereegranskat)abstract
- To increase the crash performance in automobiles it is necessary to use new techniques and materials. To produce energy absorbing components the material should have high yield strength, high elongation to fracture and strong work hardening. The total work a component absorbs during impact is the area under the stress-strain curve for unit material volume. This has lead to an interest in high strength stainless steels as crash safety components in automobiles due to their excellent material properties. The material performance of different stainless grades has been evaluated through intrinsic and simulative tests. A stainless steel bumper beam has been optimised for a VOLVO car and comparisons have been made with the present application. Simulations have been done and verified by experiments.
|
|
| 40. |
|
|
| 41. |
- Asteman, Henrik, 1973, et al.
(författare)
-
Effect of water-vapor-induced Cr vaporization on the oxidation of austenitic stainless steels at 700 and 900 degrees C - Influence of Cr/Fe ratio in alloy and Ce additions
- 2004
-
Ingår i: Journal of the Electrochemical Society. - : The Electrochemical Society. - 1945-7111 .- 0013-4651. ; 151:3, s. B141-B150
-
Tidskriftsartikel (refereegranskat)abstract
- The oxidation of 153MA, 310 and 353MA austenitic stainless steels was investigated at 700°C and 310 and 353MA at 900°C in O 2 and in O 2 + 40% H 2 O. 153MA was not studied at 900°C because it suffered excessive corrosion. The influence of gas velocity was studied. The oxidized samples were investigated by grazing angle X-ray diffraction, scanning electron microscopy/energy dispersive analysis by X-rays Auger-electron spectroscopy, and glow discharge optical emission spectroscopy. In the presence of water vapor, gas velocity strongly influenced oxidation. This effect is attributed to chromium evaporation in the form of CrO 2 (OH) 2 . Exposure in O 2 + 40% H 2 O at 700°C using high flow rates caused breakaway corrosion on all alloys. At 900°C, only the 310 and 353MA alloys were investigated. In O 2 + H 2 O environment, both alloys showed a mass loss at low flow rates due to chromium evaporation. At high flow rates, alloy 310 suffered breakaway corrosion while 353MA did not. The corrosion products consisted of a relatively thin Cr-rich (Cr,Fe) 2 O 3 oxide plus thick, iron-rich oxide islands. The greater corrosion resistance of 310 and 353MA steels in environments where chromium evaporation is a factor is attributed to the high Cr/Fe ratio. In contrast, the presence of Ce and Si in the MA grade steels appears to have little beneficial effect on breakaway corrosion triggered by Cr evaporation. © 2004 The Electrochemical Society. All rights reserved.
|
|
| 42. |
- Belov, Ilja, et al.
(författare)
-
Thermal and flow analysis of SiC-based gas sensors for automotive applications
- 2004
-
Ingår i: Proceedings of the 5th International Conference on Thermal and Mechanical Simulation and Experiments in Microelectronics and Microsystems, 2004. - : IEEE. - 0780384202 ; , s. 475-482
-
Konferensbidrag (refereegranskat)abstract
- Different block and tube mounting alternatives for SiC-based gas sensors were studied by means of temperature measurements and simulation of heat transfer and gas flow for steady state conditions. The most preferable tube mounting design was determined. Simulation-based guidelines were developed for designing tube-mounted gas sensors in the exhaust pipes of diesel and petrol engines, taking into account thermal constraints and flow conditions.
|
|
| 43. |
|
|
| 44. |
- Berlin, Rolf, 1955
(författare)
-
Accurate robot and workcell simulation based on 3D laser scanning
- 2002
-
Ingår i: Proceedings of the 33rd ISR (International Symposium on Robotics).
-
Konferensbidrag (refereegranskat)abstract
- ABSTRACT Modern production development methods are increasingly founded on computer-based tools with virtual models describing the existing or planned production process. This Virtual Manufacturing approach, with sophisticated simulation tools for 3D workcell layout and off-line robot programming, results in reduced time to market, lower production costs, and superior end products. The introduction of tools with virtual models of the present production process has contributed significantly to reduce the possibility of making costly mistakes. The need for confirmation between the real world and the virtual world is obviously critical.Quality of the workcell 3D layouts is one of the more difficult data to verify and update. Single objects like robotbases and fixtures can be adequately measured with theodolite instruments, but shape and position of all workcell peripheral objects are incorrectly assumed to be according to original layouts. This results in position errors in the virtual cell and time consuming corrections on the shop floor before production can start.Our work has been focused on evaluating the possibilities to use novel technology in 3D laser scanning and modelling in the process of making true as built models of workcell and objects, for 3D virtual robot and cell simulation. Several major projects in the automotive industry will be described in this paper. The focus of the projects has been to map both old, nearly 3D-undocumented factories, as well as verify and adjust newly built well-documented production lines. On site methods for calibration and scanning have been developed and resulting models have been imported to existing advanced 3D software tools for updating existing workcell models. This paper describes results of fast on site work, where complete bodyshops have been 3D-scanned in a single week, and complex robotcells have been verified and adjusted in an area of 3000 m2 , with an accuracy of a few millimetres.
|
|
| 45. |
|
|
| 46. |
- Blücher, D. Bengtsson, et al.
(författare)
-
Scanning kelvin probe force microscopy - A useful tool for studying atmospheric corrosion of MgAl alloys in situ
- 2004
-
Ingår i: JOURNAL OF THE ELECTROCHEMICAL SOCIETY. - : The Electrochemical Society. - 0013-4651 .- 1945-7111. ; 151:12
-
Tidskriftsartikel (refereegranskat)abstract
- Scanning Kelvin probe force microscopy (SKPFM) is used to study the initial stages of atmospheric corrosion of an AlMg alloy and of physical vapor deposition (PVD) deposited 2 μm Al dots on pure Mg. The latter system is used as a model of a two-phase AlMg alloy. The influence of CO2 was studied in situ in humid air using SKPFM. This method allows for the in situ investigation of the evolution of the Volta potential during exposure, the resolution being in the submicrometer range. The temperature was 22.0°C, and the relative humidity was 85 or 95%. The concentration of CO2 was <1 or 350 ppm. The corrosion products were analyzed by gravimetry, ion chromatography, X-ray diffraction, scanning electron microscopy, scanning Kelvin probe, and Auger electron spectroscopy. We found that the initial stages of atmospheric corrosion on magnesium are influenced by the presence of cathodic PVD-deposited aluminum. A similar effect was seen in the case of AZ91D, the aluminum-rich β-phase forming the cathodic areas. The β-phase is nobler compared to the substrate because of the higher Al content. In the absence of CO2, the corrosion attack is localized in nature whereas the presence of ambient levels of CO2 results in a more general corrosion attack. The inhibitive effect of CO2 on the atmospheric corrosion of AZ91D is explained by the formation of a passivating layer of Mg5(CO3)4(OH)2⋅5H2O. In the absence of CO2, the increase in pH originating from the cathodic reaction results in the dissolution of aluminum in the passive layer. A corrosion mechanism is proposed explaining the behavior in the two environments.
|
|
| 47. |
|
|
| 48. |
|
|
| 49. |
|
|
| 50. |
|
|
