Effect of stacking sequence on free vibration frequencies of laminated composite circular cylindrical shells

This study compares the effect of stacking sequence on natural frequencies of cylindrical shells for different end conditions and vibration modes. For this purpose, an analysis of the natural frequencies of laminated composite cylindrical shells is carried out using linear Reissner shell theory with the transverse shear deformation effects taken into account. The governing equations for the free vibration of laminated cylindrical shells are reduced to 10 first-order differential equations involving 10 unknowns. Natural frequencies and mode shapes are solved by using a combination of modal iteration and frequency trial methods for various circumferential vibration modes, stacking sequences, and end conditions, including the nonconventional ones. The results show the efficient applicability of the combination of the modal iteration and frequency trial method to the solution of the shell vibration problem, and they give valuable information on the effect of the stacking sequence on the stiffness characteristics of composite cylindrical shells under different end conditions

Vibration and Acoustics Using an Alternative Modeling Technique

In this study, the effect of weatherstrip seals on panel vibrations and structure borne noise is studied. First, a test structure is built to model vehicle's body and door; hammer impact tests are carried out to determine frequency shifts in door vibration modes with the inclusion of rubber seals. Then, a finite element model of the test structure is built. Rubber seals are modeled as spring elements, and a modal analysis is carried out. Finite element results are compared to experimental ones to check the validity of the model used. Following a parametric study to determine stiffness of linear springs, the full vehicle is modeled using finite elements, and the effect of rubber weatherstrip seals on sound pressure level (SPL) inside the passenger compartment is studied. Frequency response curves are plotted

An investigation of the effect of weatherstrip seals on vehicle vibration and acoustics using an alternative modeling technique

In this study, the effect of weatherstrip seals on panel vibrations and structure borne noise is studied. First, a test structure is built to model vehicle's body and door; hammer impact tests are carried out to determine frequency shifts in door vibration modes with the inclusion of rubber seals. Then, a finite element model of the test structure is built. Rubber seals are modeled as spring elements, and a modal analysis is carried out. Finite element results are compared to experimental ones to check the validity of the model used. Following a parametric study to determine stiffness of linear springs, the full vehicle is modeled using finite elements, and the effect of rubber weatherstrip seals on sound pressure level (SPL) inside the passenger compartment is studied. Frequency response curves are plotted. Copyright © 2014 by ASME

Gain-scheduled integrated active steering and differential control for vehicle handling improvement

This paper presents a gain-scheduled active steering control and active differential design method to preserve vehicle stability in extreme handling situations. A new formulation of the bicycle model in which tyre slip angles, longitudinal slips and vehicle forward speed appear as varying vehicle parameters is introduced. Such a model happens to be useful in the design of vehicle dynamics controllers scheduled by vehicle parameters: after having expressed the parametric bicycle model in the parametric descriptor form, gain-scheduled active steering and differential controllers are designed to improve vehicle handling at 'large' driver-commanded steering angles. Simulations reveal the efficiency of the selected modelling and controller design methodology in enhancing vehicle handling capacity during cornering on roads with varying adhesion coefficient and under variable speed operation