Abstract
Multilayered composites can be weakened by local failures, which can give rise to singular stress fields. Singularities can be removed or integrated to obtain bounded quantities which may be used for the analysis. In any case, the participation of singular stresses should be identified. Serving this purpose, a new mixed singular wedge element based on interpolation functions with a variable singularity power is developed, which can adapt to the problem and can represent the non-singular fields as a particular case. The displacements and the interlaminar stresses are assumed as nodal d.o.f. to a priori fulfill the kinematic and stress contact conditions at the material interfaces and the stress boundary conditions in point form. The application to sample cases taken from literature shows that the element can be successfully employed for the analysis of singular fields. The variable singular representation and the mixed formulation give more accurate results than their displacement-based, non-singular, or singular counterparts with a fixed singularity. The failure loads of initially delaminated specimens are accurately predicted either using the virtual crack closure technique or a mesoscale model by running in a reasonable time on a personal laptop computer.
Highlights
Multilayered composites are increasingly finding use, owing to excellent strength and stiffness-to-weight ratios, long fatigue life and advantageous energy absorption properties
A new mixed singular wedge element with a variable singularity power that can adapt to the problem and can represent the non-singular behavior as a particular case was developed for analysis of damaged composites
The numerical results proved that the present finite element simulation with mixed singular wedge elements around singularities and solid mixed elements elsewhere accurately predicts the presence and the nature of singularities, the related stress fields, the participation of the singular stresses and the regular behavior with an affordable computational effort for a laptop computer
Summary
Multilayered composites are increasingly finding use, owing to excellent strength and stiffness-to-weight ratios, long fatigue life and advantageous energy absorption properties. The accuracy of the present modeling will be assessed considering sample test cases with singular stress fields taken form the literature and initially delaminated specimens, for which experimental results are available, whose failure loads will be predicted using fracture mechanics and a mesomechanic approach. In the former case, the analysis of delamination will be carried out using the singular representation, as in the papers by Ariza et al [43] and Yao and Hu [44]. The displacement-based elements particularized from the mixed elements give less accurate predictions
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