Seminar Series - 1998-1999

Experimental Analysis of a Single Lap Adhesive Composite Joint Subjected to Quasi-static and Fatigue Loading

Equations for a Piezoelectric Parallelpiped and Piezoelectric Gyroscope

Date:  Tuesday, March 2, 1999
Time:  3:30 p.m.
Place:  W128 Nebraska Hall

Experimental Analysis of a Single Lap Adhesive Composite Joint Subjected to Quasi-static and Fatigue Loading

Ian J. Saunders
Department of Engineering Mechanics
University of Nebraska
Lincoln, NE 68588-0526
Advisor:  Yuris Dzenis

The objective of the first stage of testing was to examine the mechanisms of failure and determine the strength and life values of a lap joint configuration. Quasi-static testing was initially done to determine ultimate strength values.  These test results were compared with linear and non-linear FEM analysis. Fatigue testing in the range of 1000 to 50000 cycles were performed with load amplitudes selected based on the quasi-static results. Acoustic emission measurement currently forms an integral part of both quasi-static and fatigue tests; therefor some theoretical aspects, calibration techniques and results of acoustic emission are included. Current deformation studies and fracture mechanics mode testing are also reviewed.

Equations for a Piezoelectric Parallelpiped and Piezoelectric Gyroscope

Huiyu Fang
Department of Engineering Mechanics
University of Nebraska
Lincoln, NE   68588-0526
Advisor:  Jiashi Yang

In a manner similar to the single power series expansion in obtaining equations of piezoelectric plates and the double power series expansion in obtaining equations of piezoelectric beams, triple power series expansion in the length, width and thickness directions of a rectangular piezoelectric parallelepiped is made and substituted into the variational formulation of linear piezoelectricity. This leads to a system of zero-dimensional equations for the motion of the parallelepiped. The lowest order equations represent homogeneous stretching and shearing deformations with uniform electric fields. These equations can be considered as a generalization of the zero-dimensional theory of elastic bodies or the theories of pseudo-rigid bodies or a Cosserat point in elasticity in the sense that electric coupling is included. The equations obtained are employed in the analysis of a ceramic thickness-shear rectangular plate piezoelectric gyroscope. The effects of Coriolis and centrifugal forces are included. Output circuit and material damping are also considered. Various aspects of the behavior of the gyroscope such as the resonant frequencies, sensitivity and input impedance are calculated. A similar analysis is performed for a quartz plate gyroscope which is treated as two connected parallelepipeds. The above zero-dimensional equations have been generalized to include thermal couplings and employed in the study of self-heating of vibrating piezoelectric gyroscopes.


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