Vibration and Damping Analysis of a Multilayered Composite Plate with a Viscoelastic Midlayer

Based on the theory of Donnell and Kirchhoff hypothesis and by using the complex constant model of viscoelastic materials, the vibration equations of five-layered constrained damping plate are established. The transfer matrix method (TMM) is improved and used to solve equations. The improved TMM is more effective to solve complex structural vibration. The influence of layer numbers, thickness of each layer, and arrangement of materials on vibration behavior are discussed. It is proved that multilayered plates can more effectively reduce natural frequency and obtain higher structural loss factor. The loss factor increases with the number of whole layers. Symmetrical structure can obtain higher structural loss factor than one-direction structure. Uniform arrangement of viscoelastic materials and constrained materials can obtain higher structural loss factor than nonuniform arrangement. There is different optimum frequency with different material thickness, and the optimum frequency is not dependent from layer numbers.

Rules-Driven Materials Design Using an Informatics-Based Approach

A rules-driven, informatics-based approach to multiply-constrained materials design is outlined, employing the example of polymer coating design for silica fibers. This approach to the inverse mapping problem of structure generation from design constraints and quantitative structure-property relationships (QSPRs) emphasizes design rule generation and analysis. Using this approach addresses several issues in new materials discovery: 1) factoring a larger design problem into tractable components, 2) integrating physical and non-physical requirements (such as cost), 3) identifying information gaps that must be resolved to complete a design, and 4) identifying situations in which a solution consistent with known information is not feasible.

Strain-Temperature and Strain-Entropy Internal Constraints in Finite Thermoelasticity

Starting out with the set of unconstrained thermoelastic materials, appropriate equivalence relations are introduced as a means towards defining internally constrained materials. The construction is first carried out in strain-temperature space, and subsequently in strain-entropy space. The question of the interrelationships between the two types of constraints is examined.

Modeling of Thermal Expansion

In this paper we treat two types of thermomechanical constraints, temperature-deformation and entropy-deformation. It is shown that for the temperature-deformation constraint equilibrium states are unstable, in that certain perturbations of the equilibrium state grow exponentially. The entropy-deformation constraint, however, does not exhibit this instability. By considering the constrained materials as limits of unconstrained materials, it is shown that the instability is associated with the loss of convexity of the internal energy.