Damage Tolerance Study of Curvilinearly Stiffened Panels
Virginia Polytechnic Institute and State University, Blacksburg, Virginia, 24061
A Damage Tolerance Study of Curvilinearly Stiffened Panels
ABSTRACT
A global–local finite element analysis was performed to study the damage tolerance of curvilinearly stiffened panels fabricated using the modern additive-manufacturing process that can create so-called unitized structures. In the first step, a buckling analysis of panels was performed to determine whether the panels satisfied the buckling constraint in an undamaged state. In the second step, stress distributions in the panel were analyzed to determine the location of the critical stress under combined shear and compression loadings. Then, a fracture analysis of the curvilinear stiffened panel with a crack designed at the earlier-obtained location of the critical stress, which was the common location with the maximum magnitude of the principal stresses and von Mises stress, was performed under combined shear and tensile loadings.
Two approaches were discussed in this report using the finite elements commercial software ABAQUS; the J-integral and XFEM method. It was observed that the fracture mode in panels with different crack lengths was Mode-I under the combined load case.
The results obtained of the stress intensity factor for different crack lengths using J-integral method and XFEM matched very well.
To study the influence of the height and the thickness of stiffeners, these parameters were varied differently. It was observed that they do not have a large influence on the stress intensity factor in Mode I and II.
Under the maximum combined-loading condition, the largest effective stress-intensity factor was much smaller than the critical-stress-intensity factor.
The fracture analysis was performed for stationary crack; It will be interesting, though, to study a fatigue crack growth subjected to a cyclic loading available in ABAQUS using Paris law to predict the service life of the stiffened panel.