scholarly journals Evaluation of inertia effects in planar squeeze flow inside soft, porous layers

2020 ◽  
Vol 724 ◽  
pp. 012042
Author(s):  
G Lupu ◽  
P Turtoi ◽  
T Cicone
Keyword(s):  
Squeeze Flow ◽  
Inertia Effects ◽  
Porous Layers

Fluid Inertia Effects in a Non-Newtonian Squeeze Film Between Two Plane Annuli

1999 ◽  
Vol 122 (4) ◽  
pp. 872-875 ◽  
Author(s):  
R. Usha and ◽  
P. Vimala
Keyword(s):  
Carrying Capacity ◽  
Integral Method ◽  
Squeeze Flow ◽  
Squeeze Film ◽  
Load Carrying Capacity ◽  
Fluid Inertia ◽  
Inertia Effects ◽  
Load Carrying ◽  
Analytical Expressions ◽  
Plastic Fluids

An analysis is presented for the laminar squeeze flow of an incompressible powerlaw fluid between parallel plane annuli using the modified lubrication theory and energy integral method. The local and the convective inertia of the flow are considered in the investigation. Analytical expressions for the load carrying capacity of the squeeze film are obtained using both the methods and are compared with those based on the assumption of inertialess flow. It is observed that the inertia correction in the load carrying capacity is more significant for pseudo-plastic fluids, n<1.[S0742-4787(00)00504-X]

Theoretical Investigation of Unsteady Squeeze Flow in a Curved Newtonian Squeeze Film

2002 ◽  
Vol 124 (4) ◽  
pp. 865-869 ◽  
Author(s):  
R. Usha and ◽  
P. Vimala
Keyword(s):  
Arbitrary Shape ◽  
Normal Force ◽  
Viscous Incompressible Fluid ◽  
Circular Disk ◽  
Squeeze Flow ◽  
Squeeze Film ◽  
Load Carrying Capacity ◽  
Inertia Effects ◽  
Curvature Effects ◽  
Load Carrying

The laminar squeeze flow of a viscous incompressible fluid between a flat circular disk and an axisymmetric curved disk of arbitrary shape is investigated theoretically using modified lubrication theory. The characteristics of squeeze film are investigated through inertia and curvature effects on the normal force exerted on the upper curved moving disk described by an exponential function for the sinusoidal squeeze motion. The constant force squeezing state is also examined. It has been observed that the load carrying capacity of the curved squeeze film is strongly influenced by the curvature and inertia effects.

In Situ microscopy of the anodic etching of silicon

1995 ◽  
Vol 53 ◽  
pp. 232-233
Author(s):  
Frances M. Ross ◽  
Peter C. Searson
Keyword(s):  
Composite Structures ◽  
High Surface ◽  
High Surface Area ◽  
Chemical Properties ◽  
Selective Etching ◽  
Silicon On Insulator ◽  
Second Phase ◽  
Porous Layers ◽  
New Class ◽  
Porous Semiconductors

Porous semiconductors represent a relatively new class of materials formed by the selective etching of a single or polycrystalline substrate. Although porous silicon has received considerable attention due to its novel optical properties1, porous layers can be formed in other semiconductors such as GaAs and GaP. These materials are characterised by very high surface area and by electrical, optical and chemical properties that may differ considerably from bulk. The properties depend on the pore morphology, which can be controlled by adjusting the processing conditions and the dopant concentration. A number of novel structures can be fabricated using selective etching. For example, self-supporting membranes can be made by growing pores through a wafer, films with modulated pore structure can be fabricated by varying the applied potential during growth, composite structures can be prepared by depositing a second phase into the pores and silicon-on-insulator structures can be formed by oxidising a buried porous layer. In all these applications the ability to grow nanostructures controllably is critical.

Investigation of the Squeeze Film Dynamics Underneath a Microstructure With Large Oscillation Amplitudes and Inertia Effects

2016 ◽  
Vol 138 (3) ◽  
Author(s):  
Nadim A. Diab ◽  
Issam A. Lakkis
Keyword(s):  
Rarefied Gas ◽  
Direct Simulation Monte Carlo ◽  
Squeeze Film ◽  
Dsmc Method ◽  
Inertia Effects ◽  
Flow Parameters ◽  
Fluid Behavior ◽  
Dimensionless Groups ◽  
Simulation Monte Carlo ◽  
The Impact

This paper presents direct simulation Monte Carlo (DSMC) numerical investigation of the dynamic behavior of a gas film in a microbeam. The microbeam undergoes large amplitude harmonic motion between its equilibrium position and the fixed substrate underneath. Unlike previous work in literature, the beam undergoes large displacements throughout the film gap thickness and the behavior of the gas film along with its impact on the moving microstructure (force exerted by gas on the beam's front and back faces) is discussed. Since the gas film thickness is of the order of few microns (i.e., 0.01 < Kn < 1), the rarefied gas exists in the noncontinuum regime and, as such, the DSMC method is used to simulate the fluid behavior. The impact of the squeeze film on the beam is investigated over a range of frequencies and velocity amplitudes, corresponding to ranges of dimensionless flow parameters such as the Reynolds, Strouhal, and Mach numbers on the gas film behavior. Moreover, the behavior of compressibility pressure waves as a function of these dimensionless groups is discussed for different simulation case studies.

Free and mixed convection in horizontal porous layers with multiple heat sources

10.2514/3.167 ◽  
1990 ◽  
Vol 4 (2) ◽  
pp. 221-227 ◽  
Author(s):  
F. C. Lai ◽  
C. Y. Choi ◽  
F. A. Kulacki
Keyword(s):  
Mixed Convection ◽  
Heat Sources ◽  
Porous Layers

scholarly journals Static ultrasonic welding of carbon fibre unidirectional thermoplastic materials and the influence of heat generation and heat transfer

2021 ◽  
pp. 002199832097681
Author(s):  
F Köhler ◽  
IF Villegas ◽  
C Dransfeld ◽  
A Herrmann
Keyword(s):  
Cross Sections ◽  
Weld Line ◽  
Welding Process ◽  
Ultrasonic Welding ◽  
Thermoplastic Composites ◽  
Squeeze Flow ◽  
Anisotropic Flow ◽  
Lap Shear ◽  
Anisotropic Thermal Conductivity ◽  
Edge Defects

Ultrasonic welding is a promising technology to join fibre-reinforced thermoplastic composites. While current studies are mostly limited to fabric materials the applicability to unidirectional materials, as found in aerospace structures, would offer opportunities for joining primary aircraft structures. However, due to the highly anisotropic flow of a molten unidirectional ply undesired squeeze flow phenomena can occur at the edges of the weld overlap. This paper investigates how the fibre orientation in the plies adjacent to the weld line influences the welding process and the appearance of edge defects. Ultrasonic welding experiments with different layups and energy director configurations were carried out while monitoring temperatures at different locations inside and outside the weld overlap. The joints were characterized by single lap shear tests, analysis of corresponding fracture surfaces and microscopic cross-sections. Results showed that the anisotropic flow and the anisotropic thermal conductivity of the plies adjacent to the weld line have a distinct effect on the appearance and location of edge defects. By using energy directors that cover only part of the weld overlap area a new approach was developed to mitigate edge defects caused by the highly directional properties of the unidirectional plies.

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