Oscillatory interstitial fluid pressure and velocity in a solid tumor with partial surface fluid leakage.

This work investigates the interstitial fluid flow characteristics in a solid tumor with partial fluid leakage at the tumor surface subjected to oscillatory microvascular pressure. Solutions of the pore fluid pressure and velocity in a spherical tumor are obtained using the poroelasticity theory for small strains. It is found that partial fluid leakage at the tumor surface reduces the pore pressure drop and decreases the fluid velocity near the surface compared with those in a tumor with a fully leaking surface. Both the pore pressure and the fluid velocity decrease dramatically with an increase in the vascular frequency. The pore pressure at a vascular frequency of 1 Hz is two orders of magnitude smaller than the amplitude of the vascular pressure, and the fluid velocity at the same frequency is one order of magnitude smaller than that produced by the steady constant vascular pressure. The pore pressure amplitude may reach that of the vascular pressure under the steady state vascular pressure condition.

Heat Conduction in a Functionally Graded Plate Subjected to Finite Cooling/Heating Rates: An Asymptotic Solution.

This work investigates transient heat conduction in a functionally graded plate (FGM plate) subjected to gradual cooling/heating at its boundaries. The thermal properties of the FGM are assumed to be continuous and piecewise differentiable functions of the coordinate in the plate thickness direction. A linear ramp function describes the cooling/heating rates at the plate boundaries. A multi-layered material model and Laplace transform are employed to obtain the transformed temperatures at the interfaces between the layers. An asymptotic analysis and an integration technique are then used to obtain a closed form asymptotic solution of the temperature field in the FGM plate for short times. The thermal stress intensity factor (TSIF) for an edge crack in the FGM plate calculated based on the asymptotic temperature solution shows that the asymptotic solution can capture the peak TSIFs under the finite cooling rate conditions.

On the shear stress distribution between a functionally graded piezoelectric actuator and an elastic substrate and the reduction of its concentration.

Recent advances in material processing technologies allow the production of piezoelectric materials with functionally graded material properties. We investigate the implications of functionally graded piezoelectric materials when used as actuators for structural control by examining the distribution of the actuating shear stress under a piezoelectric actuator of a functionally graded material (FGM) on an isotropic elastic half-space. It is shown that FGM materials can be used to adjust the shear stress distribution. In particular, the concentration near the edges of a conventional homogeneous piezoelectric actuator can be significantly reduced in an FGM actuator.

Functionally graded piezoelectric materials for modal transducers for exciting bulk and surface acoustic waves.

We show that functionally graded piezoelectric materials can be used to make modal actuators through theoretical analyses of the excitation of extensional motion in an elastic rod and Rayleigh surface waves over an elastic half-plane. The results suggest alternatives with certain advantages for the excitation of bulk and surface acoustic waves.