Structural Integrity of Discontinuous Stiffened Integrally Bralded and Woven Composite Panels
Abstract
The strength and failure modes of discontinuous blade stiffened panels made of textile preform composites (three-dimensional (3D) braided (0 deg +/- 17 deg) and 3D orthogonal woven (0 deg/90 deg/90 deg)) were evaluated through 3D finite element analysis and test. Tests were conducted under quasi-static tensile and tension-tension fatigue conditions. The peel and shear stresses at the notch root were as high as 40% and 80% of the axial stress, and they caused failure initiation. Final static fracture in both braided and woven composite panels were by net section tensile failure. The average strengths of the braided and the woven panels were 433.7 MPa and 581.8 MPa, respectively. However, the initial failure of the woven panels was stiffener separation but because the load carried by the blade stiffener was only about 10% of the total load, the panels were able to carry additional load until final failure occurred in tension. The stiffener separation occurred at about 28% of the final failure load (162.7 MPa). This load level is considered as the useful capability of the panel. Thus the behavior of the woven panels was similar to the conventional tape construction. The two specimens that were tested under fatigue (S sub max = 0.6 S sub ult and R = 0.1) survived one million cycles, but the woven panel lost its stiffener, and the residual strength of braided and woven composite specimens were 88.6% and 90.9% of their respective static strengths.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 1999
- Accession Number
- ADA363127
Entities
People
- Kunigal Shivakumar
- M. J. Sundaresan
- V. S. Avva
Organizations
- North Carolina Agricultural and Technical State University