Multi-objective Optimization of Co-cured Composite Laminates with Embedded Viscoelastic Damping Layer

Presented herein is a methodology for the multi-objective optimization of damping and bending stiffness of cocoured composite laminates with embedded viscoelastic damping layer. The embedded viscoelastic damping layer is perforated with a series of small holes, and the ratio of the perforation area to the total damping area is the design variable of the methodology. The multi-objective optimization is converted into a single-objective problem by an evaluation function which is a liner weigh sum of the two sub-objective functions. The proposed methodology was carried out to determine the optimal perforation area ratios of two viscoelstic layers with different perforation distance embedded in two composite plates. Both the optimal perforation area ratios are approximate to 2.2%. However, the objective value of the plate with greater perforation distance in embedded viscoelatic layer is much greater.

Energy Decay in Thermoelasticity with Viscoelastic Damping of General Type

In this paper we consider an n-dimensional thermoelastic system with viscoelastic damping. We establish an explicit and general decay rate result without imposing restrictive assumptions on the behavior of the relaxation function at infinity. Our result allows a larger class of relaxation functions and generalizes previous results existing in the literature.

FORCED VIBRATION AND SOUND RADIATION OF A RECTANGULAR PLATE WITH VISCOELASTIC BOUNDARY SUPPORTS

A method for the forced vibration and sound radiation of a rectangular plate with viscoelastic boundary supports is proposed.The method is based on damped complex modes analysis method.Using the damped complex modes of the plate system,the modal equation of the plate motion becomes completely uncouped.The sound radiation pressure is obtained by numerical integration of the Rayleigh integral.Effects of the viscoelastic boundary supports on the vibration response and the radiated sound pressure of the vibrating plate are discussed by an example.

DYNAMIC BEHAVIOR ANALYSIS OF VISCOELASTICALLY DAMPED STRUCTURES

Analysis method for the dynamic behavior of viscoelastically damped structures is studied.A finite element model of sandwich beams with eight degrees of freedom is set up and the finite element formulation of the equations of motion is given for the viscoelastically damped structures.An iteration method for solving nonlinear eigenvalue problems is suggested to analyze the dynamic behavior of viscoelastically damped structures. The method has been applied to the complex model analysis of a sandwich cantilever beam with viscoelastic damping material core.

Nonlinear Fractional-Order Dynamic Stability of Fluid-Conveying Pipes Constituted by the Viscoelastic Materials with Time-Dependent Velocity

Considering that the fluid-conveying pipes made of fractional-order viscoelastic material such as polymeric materials with pulsatile flow are widely applied in engineering,we focus on the stability and bifurcation behaviors in parametric resonance of a viscoelastic pipe resting on an elastic foundation.The Riemann–Liouville fractional-order constitutive equation is used to accurately describe the viscoelastic property.Based on this,the nonlinear governing equations are established according to the Euler–Bernoulli beam theory and von Karman’s nonlinearity,with using the generalized Hamilton’s principle.The stability boundaries and steady-state responses undergoing parametric excitations are determined with the aid of the direct multiple-scale method.Some numerical examples are carried out to show the effects of fractional order and viscoelastic coefficient on the stability region and nonlinear bifurcation behaviors.It is noticeable that the fractional-order viscoelastic property can effectively reconstruct the dynamic behaviors,indicating that the stability of the pipes can be conspicuously enhanced by designing and tuning the fractional order of viscoelastic materials.

GENERAL DECAY RATE ESTIMATES FOR VISCOELASTIC WAVE EQUATION WITH VARIABLE COEFFICIENTS

The authors study decay properties of solutions for a viscoelastic wave equation with variable coefficients and a nonlinear boundary damping by the differential geometric approach.