ANALYSIS OF COMPOSITE WING SPAR WITH CUTOUTS FOR TENSILE LOAD

The use of composites in aircraft structures is steadily increased and now become part of daily life. In construction of multi-cell aircraft wing, cutouts are commonly provided in the wing spars and ribs to facilitate the fuel transfer across cells. While the web of the spar is expected to transfer shear loads under an overall bending load, presence of such discontinuities are of great concern. In particular, wing spars made of fiber reinforced composites, such discontinuities may result in fiber tear and are well known locations of stress concentration. Present work attempts to analyze a carbon fiber composite (CFC) and Glass fiber composite wing spar, with cutouts, under cantilever beam conditions with the tension load applied at one end of the spar to induce a pure bending stress at the cutout, through FE analysis. The data measured extensively during the tests was employed for varying thickness and diameter to identify the stress concentrations, critical failure locations. This study is to establish the need for modeling the whole loading assembly to achieve the results.