| 11. |
- Strömberg, Niclas, 1968-
(författare)
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Finite element treatment of two-dimensional thermoelastic wear problems
- 1999
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Ingår i: Computer Methods in Applied Mechanics and Engineering. - : Elsevier. - 0045-7825 .- 1879-2138. ; 177:3-4, s. 441-455
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Tidskriftsartikel (refereegranskat)abstract
- The present paper concerns the numerical treatment of thermoelastic wear problems. The governing equations of thermoelasticity coupled to Signorini contact, Coulomb's friction and Archard's wear are formulated as a system of discrete equations. This equation system is solved, using a Bouligand differentiable Newton method, for five problems of didactic nature.
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| 12. |
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| 13. |
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| 14. |
- Dugic, Izudin, 1962-, et al.
(författare)
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The effect of chemical composition on the metal expansion penetration in grey cast iron
- 1999
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In some grey cast iron components which are cast in sand moulds, the metal sometimes penetrates into the mould producing defects and causing difficulties when cleaning the components. To improve knowledge of the metal penetration mechanism a series of test castings was performed at ITT Flygt’s foundry where the influence of chemical composition was studied. The chemical composition of the melt was changed in the ladle before pouring. The result showed that the carbon and phosphorus content had an influence on metal penetration. The metal penetration tendency decreased when decreasing the carbon content as well as when increasing the phosphorus content. The penetration areas were analysed in a Scanning Electron Microscope (SEM) with Energy Dispersive Analysis (EDS). The analysis showed that the average chemical composition in the penetration zones was close to the initial composition of the alloy. Consequently, no significant macro segregation of carbon or phosphorous could be observed. The whole casting process was simulated with the software MAGMAsoftTM, in order to investigate the solidification characteristics as well as the porosity formation in the casting studied. For this, a special module for cast iron was used, MAGMAironTM, where nucleation and growth of all relevant phases are considered. During simulation it is possible to detect the areas where porosities are likely to be formed. The results show that expansion penetration generally occurs in the same areas depending on the mode of solidification. The inoculation and solidification behaviour will result in excess or deficiency of the metal at the end of solidification, which will lead to either metal penetration or formation of porosities.
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| 15. |
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| 16. |
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| 17. |
- Berbyuk, Viktor, 1953, et al.
(författare)
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Internal torques of human upper extremity during its optimal motion in vertical plane
- 1997
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Ingår i: The Tenth Biomechanics Seminar. - 1100-2247. ; 10, s. 66-83
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Konferensbidrag (refereegranskat)abstract
- In the paper a number of optimal control problems for the motion of the human upper extremity (HUE), for different types of working tasks, are considered. The performance index used in these problems is the integral over the duration of the working task of the sum of the square of the controlling stimuli acting at the joints of the human arm. Under some conditions this performance index can be used for evaluation of the muscles' energy expenditure during human movements. The HUE is simulated by a plane multibody system of rigid masses. The system comprises the three elements with mass and rotatory inertia modelled the upper arm, the forearm and the hand. The controlled motions of the mechanical system are described in terms of joint angles and Cartesian coordinates of the shoulder joint, through the application of Lagrange's equations. The main aim of the study is an investigation of the interaction between the gravity forces and the internal torques acting at the joints during goal-directed extremal motions of the HUE. The analysis of the internal torques, energetic and viscoelastic characteristics of the shoulder, the elbow and the wrist joints for the exstremal controlled motions of the human arm under the external load acting on the hand has been done.
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| 18. |
- Drugge, Lars, et al.
(författare)
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The nonlinear behaviour of a pantograph current collector suspension
- 1999
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Ingår i: Proceedings of the 1999 ASME Design Engineering Technical Conferences.
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Konferensbidrag (refereegranskat)abstract
- The pantograph-catenary system is a critical component for trains required to run at higher speeds. The pantograph often includes nonlinear characteristics and the scope of this work is to investigate if nonlinear dynamic phenomena can occur in an existing design. A model of a pantograph suspension subsystem has been developed according to physical parameter values of the head suspension of the Schunk WBL88/X2 pantograph, providing electric power to the Swedish high-speed train X2. Studies of the system response for different force excitation show both harmonic, subharmonic and chaotic behaviour for the investigated parameter regions.
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| 19. |
- Berbyuk, Viktor, 1953
(författare)
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Inverse dynamics and Fourier-based approach to solve optimal control problems for multi-link mechanisms
- 1997
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Ingår i: The NATO Advanced Study Institute on Computational Methods in Mechanisms. ; 2, s. 431-440
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Konferensbidrag (refereegranskat)abstract
- This paper is concerned with the investigation of multi-link mechanism controlled motion between fixed boundary conditions and given constraints on the phase coordinates. The moduli of the controlling moments at the hinges between the links are bounded. A computational method to the mathematical modeling of the optimal control laws which govern multi-link mechanism reaching motion is presented. This method is based on Fourier and spline approximations of the independently variable functions and inverse-dynamics approach. The method proposed makes it possible to satisfy the boundary conditions and some constraints on the phase coordinates automatically and accurately. The efficiency of the proposed method is illustrated by the solution of the energy-optimal control problem of a plane mobile three-link manipulator with a load on the grip.
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| 20. |
- Bäckström, Mikael, et al.
(författare)
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A step towards integrated supervisory control of complex machining processes
- 1998
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Ingår i: Changing the ways we work : shaping the ICT-solutions for the next century : proceedings of the Conference on Integration in Manufacturing, Göteborg, Sweden, 6-8 October 1998. - Amsterdam : IOS press. - 9051994265 ; , s. 817-
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Konferensbidrag (refereegranskat)
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