PREDICTION AND MEASUREMENT OF SOME DYNAMIC PROPERTIES OF SANDWICH STRUCTURES WITH HONEYCOMB AND FOAM CORES
✍ Scribed by E. NILSSON; A.C. NILSSON
- Publisher
- Elsevier Science
- Year
- 2002
- Tongue
- English
- Weight
- 295 KB
- Volume
- 251
- Category
- Article
- ISSN
- 0022-460X
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✦ Synopsis
Some dynamical properties of sandwich beams and plates are discussed. The types of elements investigated are three-layered structures with lightweight honeycomb or foam cores with thin laminates bonded to each side of the core. A six order di!erential equation governing the apparent bending of sandwich beams is derived using Hamilton's principle. Bending, shear and rotation are considered. Boundary conditions for free, clamped and simply supported beams are formulated. The apparent bending sti!ness of sandwich beams is found to depend on the frequency and the boundary conditions for the structure. Simple measurements on sandwich beams are used to determine the bending sti!ness of the entire structure and at the same time the bending sti!ness of the laminates as well as the shear sti!ness of the core. A method for the prediction of eigenfrequencies and modes of vibration are presented. Eigenfrequencies for rectangular and orthotropic sandwich plates are calculated using the Rayleigh}Ritz technique assuming frequency dependent material parameters. Predicted and measured results are compared.
2002 Elsevier Science Ltd.
(10)
The integration over time is from t to t and over the length from 0 to ¸. E!ecting the variation as demonstrated in reference [22], it is found that the displacement w and the angular displacement must satisfy the di!erential equations
On eliminating the equation governing w is obtained as !2D D *w *x #2D I M *w *x*t !(D #2D #I M G C H) *w *x*t #G C H D *w *x # *w *t #I M *w *t " *p *x (D #2D )!G C Hp!I M *p *t . (13)