Sökning: "Pre-stress"

Visar resultat 1 - 5 av 12 avhandlingar innehållade ordet Pre-stress.

1. 1. Vibration Frequencies as Status Indicators for Tensegrity Structures

   Författare :Nasseradeen Ashwear; Anders Eriksson; Karl-Gunnar Olsson; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Tensegrity; Pre-stress; Vibration; Health monitoring; Buckling; Temperature effect; Vibration health monitoring VHM; Tensegritet; Förspänning; Vibration; Hälsokontroll; Knäckning; Temperatureffekt; Vibrationsbaserad hälsokontroll; Engineering Mechanics; Teknisk mekanik;

   Sammanfattning :  Applications of vibration structural health monitoring (VHM) techniques are increasing rapidly. This is because of the advances in sensors and instrumentation during the last decades. VHM uses the vibration properties to evaluate many civil structures during the design steps, building steps and service life. LÄS MER

3. 2. Vibration-based Assessment of Tensegrity Structures

   Författare :Nasseradeen Ashwear; Eriksson Anders; Thomas Abrahamsson; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Tensegrity; Pre-stress; Vibration; Health monitoring; Buckling; Temperature effect; Vibration health monitoring VHM; Optimization; Engineering Mechanics; Teknisk mekanik;

   Sammanfattning : Vibration structural health monitoring (VHM) uses the vibration properties to evaluate many civil structures during the design steps, building steps and service life.The whole function, expressed by stiffness and frequencies of tensegrity structures are primarily related to the level of pre-stress. LÄS MER

4. 3. Waveguide Finite Elements Applied on a Car Tyre

   Författare :Carl-Magnus Nilsson; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; wave equation; wave solution; waveguide; finite element; spectral finite element; tyre noise; tyre vibration; input power; shells; pre stress; fluid shell coupling; axi--symmetric;

   Sammanfattning : Structures acting as waveguides are quite common withexamples being, construction beams, fluid filled pipes, railsand extruded aluminium profiles. Curved structures like cartyres and pipe-bends may also be considered as waveguides. Wavesolutions in such structures may be found by a method calledthe Waveguide Finite Element Method or WFEM. LÄS MER

5. 4. Stiffness and vibration properties of slender tensegrity structures

   Författare :Seif Dalil Safaei; Gunnar Tibert; René Motro; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Tensegrity booms; Tensegrity grids; Tensegrity power lines; Finite element analysis; Genetic algorithm; Flexibility analysis; Form-finding; Pre-stress design; Optimization;

   Sammanfattning : The stiffness and frequency properties of tensegrity structures are functions of the pre-stress, topology, configuration, and axial stiffness of the elements. The tensegrity structures considered are tensegrity booms, tensegrity grids, and tensegrity power lines.A study has been carried out on the pre-stress design. LÄS MER

7. 5. Robust Preconditioners Based on the Finite Element Framework

   Författare :Erik Bängtsson; Maya Neytcheva; Per Lötstedt; Svetozar Margenov; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; FEM; iterative solution method; algebraic multilevel preconditioner; sparse approximate inverse; block preconditioner; Schur complement approximation; nonsymmetric saddle point matrix; isostatic glacial adjustment; pre-stress advection; elasticity; viscoelasticity; in compressible solid; ABAQUS; BEM DDM; Scientific Computing; Beräkningsvetenskap;

   Sammanfattning : Robust preconditioners on block-triangular and block-factorized form for three types of linear systems of two-by-two block form are studied in this thesis. The first type of linear systems, which are dense, arise from a boundary element type of discretization of crack propagation problems. LÄS MER