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Visar resultat 1 - 5 av 49 avhandlingar som matchar ovanstående sökkriterier.

1. 1. Vibrations induced by surface roughness in nonlinear rolling contacts

   Författare :Oskar Erik Lundberg; Ines Lopez Arteaga; Svante Finnveden; Will Graham; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Rolling contact; nonlinear contact; contact stiffness; contact filter; state-dependent method; relative displacement; wheel-rail contact; Vehicle and Maritime Engineering; Farkostteknik;

   Sammanfattning : For efficient transportation in either trains, busses or passenger cars, rolling elements such as wheels, tyres, bearings and transmission elements are fundamental. The energy efficiency and the generation of noise and vibrations in rolling contacts depend on the surface roughness of contacting bodies. LÄS MER

3. 2. Probing nonlinear electrical properties at the nanoscale : Studies in multifrequency AFM

   Författare :Riccardo Borgani; David B. Haviland; Peter Grütter; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Atomic Force Microscopy; Nonlinear dynamics; Multifrequency; Contact potential difference; Conductance; Fast dynamics; Fysik; Physics;

   Sammanfattning : Nanostructured materials promise great advances in diverse and active research fields such as energy harvesting and storage, corrosion prevention and high-density memories. Electrical characterization at the nanometer scale is key to understanding and optimizing the performance of these materials, and therefore central to the progress of nanotechnology. LÄS MER

4. 3. On efficient and adaptive modelling of friction damping in bladed disks

   Författare :Mohammad Afzal; Leif Kari; Ines Lopez Arteaga; Muzio M Gola; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; High cycle fatigue; Friction contact; Jacobian matrix; Shroud contact; Strip damper; Multiharmonic balance method; Contact stiffness; Cyclic symmetry; Nodal diameter; Magnetostrictive actuator; Magnetic field; Engineering Mechanics; Teknisk mekanik;

   Sammanfattning : This work focuses on efficient modelling and adaptive control of friction damping in bladed disks. To efficiently simulate the friction contact, a full-3D time-discrete contact model is reformulated and an analytical expression for the Jacobian matrix is derived that reduces the computation time drastically with respect to the classical finite difference method. LÄS MER

5. 4. Reduced Order Modeling and Substructuring : Applications in Nonlinear Structural Dynamics

   Författare :Linus Andersson; Byggnadsmekanik; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Reduced order modeling; Substructuring; Nonlinear dynamics; Geometrically nonlinear; Modal derivatives; Blast loading; Soft-body impact; Glass structures;

   Sammanfattning : A structural design process typically involves various load cases for which a sufficient load-bearing capacity must be demonstrated. In addition to static load cases, a verification of dynamic loads, such as blast and impact loading, may be required. LÄS MER

7. 5. Computer Aided Angioplasty : Patient-specific arterial modeling and smooth 3D contact analysis of the stent-balloon-artery interaction

   Författare :Dimitrios Kiousis; Gerhard Holzapfel; Kenneth Runesson; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Contact; continuous surfaces; B-splines; balloon angioplasty; stenting; FEM; Bioengineering; Bioteknik;

   Sammanfattning : Paper A: In this paper, the development and implementation of a contact algorithm based on C2-continuous surface representations is discussed. In 3D contact simulations involving models with arbitrarily curved surfaces (as in the case of vessel walls), the discretization of the contact surfaces by means of facet-based techniques could lead to numerical instabilities and finally loss of quadratic convergence. LÄS MER