Sökning: "damping ratios"

Visar resultat 1 - 5 av 11 avhandlingar innehållade orden damping ratios.

  1. 1. Bridge Monitoring to Allow for Reliable Dynamic FE Modelling : A Case Study of the New Årsta Railway Bridge

    Författare :Johan Wiberg; Håkan Sundquist; Raid Karoumi; Björn Paulsson; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; bridge monitoring; FE modelling; signal analysis; torsion; warping; modulus of elasticity; natural frequency; damping; finite differences; Civil engineering and architecture; Samhällsbyggnadsteknik och arkitektur;

    Sammanfattning : Today’s bridge design work in many cases demands a trustworthy dynamic analysis instead of using the traditional dynamic amplification factors. In this thesis a reliable 3D Bernoulli-Euler beam finite element model of the New Årsta Railway Bridge was prepared for thorough dynamic analysis using in situ bridge monitoring for correlation. LÄS MER

  3. 2. Studies of sound generation and propagation in flow ducts

    Författare :Fabrice Ducret; Mats Åbom; Andy Moorhouse; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; two-port; plane wave; HVAC system; tailpipe; exhaust system; flexible duct; pipe; reflection coefficient; impedance; flow noise; vorticity; damping; scaling laws; impedance; transmission loss; perforated plate; slit; non linearity; Acoustics; Akustik;

    Sammanfattning : This thesis contains three papers investigating problems of interest for noise control in ducts. The first part of this thesis treats the sound propagation in rectangular ducts with flexible walls. Various experimental techniques are performed to measure the internal sound propagation and radiation to the surrounding. LÄS MER

  4. 3. Mechanical Characterization of Engineering Materials by Modal Testing

    Författare :Daniel Larsson; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; material variability; modal testing; non-destructive test methods; damping ratios; timber beams; plastic panels; aluminium panel; elastic constants; concrete curing; wood-based panels; solids; high-strength concrete; anisotropic materials;

    Sammanfattning : This thesis deals with the use of modal testing for establishing elastic constants of engineering materials and for indicating material variability in terms of stiffness and damping properties. The methodology using modal testing techniques, is applied to timber beams, high strength concrete prisms, wood-based panels (oriented strand board and chipboard), an aluminium alloy panel and plastic laminate panels (high-pressure laminate). LÄS MER

  5. 4. Foam, Fire and Free Volume - Chemical and Physical Aspects of Porous Polymers

    Författare :Anna Andersson; Centrum för analys och syntes; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Poisson ratio; vibration damping; acoustic impedance; cell morphology; hyperbranched polymer; Polymer foams; free volume; positron annihilation; supercritical fluid.;

    Sammanfattning : Automotive seating has been under continous development since it was described for the first time in 1885. At that time one could read about a “padded leather bench seat sitting on springs mounted directly to the frame of a horse-less carriage”. LÄS MER

  7. 5. Some aspects of the dynamic soil-structure interaction of a portal frame bridge

    Författare :Mahir Ülker-Kaustell; Raid Karoumi; Mohammed Hjiaj; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Building engineering; Byggnadsteknik;

    Sammanfattning : For certain bridge types, the influence of soil-structure interaction (SSI) may have an important contribution to the stiffness and damping of the structural system. From a design point of view, this influence may be both conservative and non-conservative and therefore, an increased knowledge within this field could lead to better design assumptions. LÄS MER