Interlaminar strains at the free-edge of a hole for thick composites in compression
The experimental technique of moire interferometry was extended to take measurements of in-plane deformations on the cylindrical surface of a hole in thick laminated composites. A replication scheme was developed to produce high-frequency diffraction gratings on singly-curved surfaces. Techniques were developed to interrogate specimen gratings on 25.4 mm (1 in.) diameter holes in order to study free-edge effects on the hole surface. Interlaminar deformations were measured on a ply-by-ply basis for the first time on the cylindrical surface of a hole. Results are presented for a graphite/epoxy composite laminate with a (90{sub 2}/0{sub 4})P{sub 4s} stacking sequence. Interlaminar normal and shear strains were determined and plotted versus the ply number at angular locations of 0{degrees}, 45{degrees} and 90{degrees} with respect to the loading axis. Strong variations of strains with angular position were revealed. Interlaminar shear strains along a 0{degree}/90{degree} interface were measured and plotted as a function of the angular position. The shape of the curve compares favorably with analytical results found in the literature for a similar geometry. 18 refs., 8 figs.
- Research Organization:
- Oak Ridge National Lab., TN (USA)
- Sponsoring Organization:
- DOD; Department of Defense, Washington, DC (USA)
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 6020922
- Report Number(s):
- CONF-9106131-1; ON: DE91008883; CNN: N00014-90-J1688; N0014-86-K0799; TZ-689900-0A57N
- Country of Publication:
- United States
- Language:
- English
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