Stress analysis of clamped-free grid composite cylindrical shell under various end loadings

ARASHMEHR JAFAR, RAHIMI GHOLAMHOSSEIN, RASOULI FAZEL

(Mechanical Engineering Department, Tarbiat Modares University, Tehran 14115-143, Iran)

Abstract:Stress analysis of cylindrical grid-stiffened composite shells was conducted under transverse loading, pure bending, torsion and axial compression under clamped-free boundary condition. Electrical strain gauges were employed to measure the strains in transverse loading case to validate the finite element analysis which was conducted using ANSYS software. Good agreement was obtained between the two methods. It was observed that stiffening the composite shell with helical ribs decreased the average equivalent Von Mises stress on the shell. The reduction of the stress seemed to be higher in the intersection of two ribs. It was also seen that the stress reduction ratio was higher when the structure was under bending compared to torsion and axial compression. The reduction ratio was approximately 75% in pure bending in the intersection point of the ribs, while it was approximately 25% in torsion. Therefore, it is concluded that the presence of the ribs is more effective under bending. Failure analysis was done using Tsai-Wu criterion. The ribs were observed to result in maximum and minimum increase in the failure load of the structure under transverse bending and torsional loading, respectively.

Key words:stiffened composite shell; end loading; stress analysis; failure load