Stability analysis on composite ribbed panel with large open-hole

The stability of composite ribbed panel with large open-hole is analyzed by finite element software Patran/Nastran. Buckling eigenvalues and modals in different reinforced models are compared. It can be seen from the results that the stability of composite laminate with open-hole is improved with reinforcement, but the effect is not obvious. So, it needs to improve the stability through the strengthened ribs. Stability of composite ribbed panel is better than that of panel without rib and stability declines with the increase of the distance between rib and center of the open-hole. The boundary of buckling modal is always located on the ribs. The eigenvalue of composite ribbed panel with lengthwise ribs is 2.13 while that of transverse is 1.08. Lengthwise ribs have a significant effect on the stability of composite ribbed panel, so it is appropriate to enhance the number of lengthwise ribs in the engineering application.