Influence Of Fabrication Imperfections Research Articles

Influence of fabrication imperfections on dynamic response of a sandwich composite panel of a ship deck structure

The dynamic behavior of bebonded sandwich plates at the skin/core interface is analysed. The finite element code COSMOS/M is used to analyse natural frequencies and mode shapes of the sandwich plates with a ellipse shape debonding area. The delamination model has been developed by using the surface-to-surface contact option. In case of surface-to-surface contact, the FE meshes of adjacent plies do no need to be identically. The influence of the diameters ratio of the debonded area, on the modal parameters of clamped sandwich plates is investigated. Parametric calculus of the sandwich plate, having various diameters ratios (Dx/Dy = 0.5; 0.75; 1) for delaminated area, have been considered. It has been observed that all the above mentioned ratios are contributing to the changes in dynamic responses of the sandwich plate.

Analysis and Design of a Polygonal Oblique Beam for the Butterfly Vibratory Gyroscope with Improved Robustness to Fabrication Imperfections.

This paper focuses on structural optimization of a Butterfly vibratory gyroscope (BFVG). An oblique suspension beam adopting polygonal cross-section is proposed in order to enhance the sensitivity and robustness. The operation principles of the BFVG are introduced. The suspension beam, which was found to be the key component, is selectively stressed. Varying cross sections of the suspension beam, including parallelogram, pentagon, hexagon, platform of pentagon, L-shaped and convex shapes are compared with each other. In particular, in order to show the advantages of the proposed polygonal cross-section, the convex cross-section is used as a reference. The influence of fabrication imperfections, which includes alignment error, silicon thickness error, etching depth error, upper width error, bottom width error and deep reactive-ion etching (DRIE) verticality error, on the oblique beam’s spindle azimuth angle of the two cross-sections is analyzed. Further, the quadrature error of two cross-sections with a fabrication defect is analyzed. The theoretical arithmetic results suggest that a polygonal cross-section beam is much more stable than a convex cross-section beam in most cases. The robustness of the fabrication imperfection is improved nine-fold and the quadrature error due to fabrication defect is reduced by 70 percent with a polygonal cross-section. It could be a better candidate for BFVG’s oblique beam, which would provide a gyroscope with good robustness and repeatability.

Accelerating the Calibration of Multihole Pressure Probes by Applying Advanced Computational Methods

The miniature multihole pneumatic pressure probe is widely regarded as a cost-effective, easy-to-use, and accurate method for performing two- or three-dimensional flow field measurements in turbomachinery. The major downside to the use of these probes is that the influence of fabrication imperfections on probe characteristics necessitates an extensive and highly time-intensive and, therefore, costly calibration of each individual probe. Unless these probes can be fabricated to such standards that make individual probe calibrations superfluous, the only way to significantly reduce the time and costs associated with probe calibration is to shorten the calibration process. The latter is only possible if all essential information can be obtained from less calibration data. This paper describes an approach to the calibration of a series of multihole pressure probes in which advanced computational methods are used to make this possible. By exploiting the key features of a probe’s characteristic this approach requires only a fraction of the size of a conventional calibration database for the accurate modeling of the relationships between port pressures and flow conditions. As a result, calibration time and costs can be reduced without the sacrifice of quality.

Performance estimation and yield analysis of an OEIC passive duplexer

For the design and fabrication of an OEIC duplexer an analysis has been performed to estimate the influence of fabrication imperfections of cross-sectional and dispersive design parameters on the operation of the device. Required fabrication tolerances and yield can thus be predicted.