On the robustness of finite element procedures based on Virtual Crack Closure Technique and fail release approach for delamination growth phenomena. Definition and assessment of a novel methodology

Formulation and assessment of an enhanced finite element procedure for the analysis of delamination growth phenomena in composite structures

“…The present paper can be considered as a sequel of the Ref. 10. As in Ref.10 the attention is addressed to the analysis of the behaviour of a circular delamination of known dimension and position considered as pre-existing within a structure and which growth process is assumed to take place in the original defect plane.…”

“…The robustness of procedure based on VCCT was investigated by Krueger [12][13] who analysed effects of choice of element types, integration order and analyses parameters (such as release tolerance,damping factors and so on) on delamination growth simulation. Pietropaoli and Riccio [10] -3/35-analysed the robustness of finite element procedures based on Virtual Crack Closure Technique and fail release approach for delamination growth phenomena and discussed their inherently dependence on the load increment and element size in the frame of non linear incremental analyses by means of theoretical considerations. The Authors also proposed a novel finite element procedure named SMART-APPROACH [10], which was able to define an automatic adjustment of the load step size on the basis of the Strain Energy Release Rate computed and of the shape of the delamination at each load level of a non linear incremental analysis.…”

“…Pietropaoli and Riccio [10] -3/35-analysed the robustness of finite element procedures based on Virtual Crack Closure Technique and fail release approach for delamination growth phenomena and discussed their inherently dependence on the load increment and element size in the frame of non linear incremental analyses by means of theoretical considerations. The Authors also proposed a novel finite element procedure named SMART-APPROACH [10], which was able to define an automatic adjustment of the load step size on the basis of the Strain Energy Release Rate computed and of the shape of the delamination at each load level of a non linear incremental analysis. The effectiveness of this procedure was proved on a stiffened panel with an embedded circular delamination subjected to static compressive loads.…”

“…The robustness of the SMART-APPROACH was assessed in Ref. 10 taking into account only the load increment size without analysing effects of the mesh density in the damaged area. The present paper can be considered as a sequel of the Ref.…”

“…straight or circular/elliptical -2/35-when modelled by using orthogonal meshes with edges parallel or orthogonal to the delamination front). When the delamination growth is of concern, the VCCT can be used in conjunction with interface elements [5][6][7] or with a fail release approach [8][9][10] whose effect is that to simulate the growth process by releasing constraints between crack faces when the Strain Energy Release Rate level overcomes critical values (instantaneous propagation). However, during the propagation the delamination front may assume complex and non-smoothed shapes with corners.…”