Torsional response of stiffened circular composite spar

보강된 복합재 원형 스파의 비틀림 거동

  • Received : 2019.03.07
  • Accepted : 2019.03.27
  • Published : 2019.03.31


To reduce the structural weight, thin-walled circular composite tube has been used as a main spar of high altitude-long endurance unmanned air vehicle(HALE UAV). Predicting the torsional response of stiffened circular spar is complex due to the inhomogeneous nature of section properties, which are dependent on fiber architecture and constituent material properties. The stiffener were placed in the top and bottom sectors of a tube to increase the torsional capabilities such as the rigidity and buckling strength. Numerical simulations were performed to estimate the effect of the stiffener on the torsional capacities. A static experimental test was performed on a stiffened tube, and the test results were compared with a numerical model. The numerical models showed good correlation and demonstrated the ability to predict the torsional capacity. Results presented herein will exhibit the effectiveness of stiffener on torsional strength and stiffness.

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Fig 1. Typical wing cross section

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Fig 2. Wing structure

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Fig 3. Schematic diagram of a circular spar with cap

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Fig 4. Setup in torsion test

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Fig 5. Dimension of test specimen

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Fig 6. Test specimens

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Fig 7. Torsional response for M30-1

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Fig 8. Torsional response for M30-2

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Fig 9. Torsional response for M30-3

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Fig 10. Torsional response for M30-4

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Fig 11. Torsional response for M30-5

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Fig 12. Torsional buckling ratio versus inplane stiffness ratio

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Fig 13. Buckling mode of tubular composite tube

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Fig 14. FEM model for torsional rigidity analysis

Table 1. Summary of layup and dimension of specimen

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Table 2. Material properties of CFRP lamina

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Table 3. Torsional buckling strength versus inplane stiffness

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Table 4. Comparison of torsional buckling strength between tests and numerical results

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Table 5. Comparison of torsional rigidity between tests and numerical results

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