TY - JOUR
T1 - Formulation of a mixed-mode multilinear cohesive zone law in an interface finite element for modelling delamination with R-curve effects
AU - Mosbjerg Jensen, Simon
AU - Martos, M. J.
AU - Bak, Brian Lau Verndal
AU - Lindgaard, Esben
PY - 2019/5/15
Y1 - 2019/5/15
N2 - A constitutive model for an interface finite element is proposed to enable simulation of delamination in composite materials with R-curve effects. The constitutive model is formulated in the framework of cohesive zone modelling (CZM). In essence, a multilinear CZ law with an arbitrary number of line segments is developed. The CZ law seeks to enable constitutive modelling of failure mechanisms on multiple scales within the fracture process zone and reduce conventional a priori assumptions regarding the shape of the CZ law. The CZ law relies on damage mechanics, an equivalent one-dimensional formulation, and criteria for mode interactions to simulate delamination under mixed-mode loading. Special emphasis is put on the derivation of interpolation formulas and a constitutive tangent stiffness tensor for the multilinear formulation. The constitutive model is implemented in the commercial FE program ANSYS Mechanical, for implicit finite element analysis (FEA), using user-programmable features. The implementation is verified through single interface element numerical studies, and its applicability is demonstrated by simulating an experiment of quasi-static delamination showing large-scale fiber bridging in pure mode I DCB glass-fiber epoxy specimens. Experimental measurements and simulation outputs using the novel cohesive element is compared to those of the conventional bi- and trilinear CZ laws.
AB - A constitutive model for an interface finite element is proposed to enable simulation of delamination in composite materials with R-curve effects. The constitutive model is formulated in the framework of cohesive zone modelling (CZM). In essence, a multilinear CZ law with an arbitrary number of line segments is developed. The CZ law seeks to enable constitutive modelling of failure mechanisms on multiple scales within the fracture process zone and reduce conventional a priori assumptions regarding the shape of the CZ law. The CZ law relies on damage mechanics, an equivalent one-dimensional formulation, and criteria for mode interactions to simulate delamination under mixed-mode loading. Special emphasis is put on the derivation of interpolation formulas and a constitutive tangent stiffness tensor for the multilinear formulation. The constitutive model is implemented in the commercial FE program ANSYS Mechanical, for implicit finite element analysis (FEA), using user-programmable features. The implementation is verified through single interface element numerical studies, and its applicability is demonstrated by simulating an experiment of quasi-static delamination showing large-scale fiber bridging in pure mode I DCB glass-fiber epoxy specimens. Experimental measurements and simulation outputs using the novel cohesive element is compared to those of the conventional bi- and trilinear CZ laws.
KW - Delamination
KW - Cohesive zone model
KW - Interface finite element
KW - Damage modelling
KW - Mixed-mode fracture
KW - Fiber bridging
UR - http://www.scopus.com/inward/record.url?scp=85062640006&partnerID=8YFLogxK
U2 - 10.1016/j.compstruct.2019.02.029
DO - 10.1016/j.compstruct.2019.02.029
M3 - Journal article
VL - 216
SP - 477
EP - 486
JO - Composite Structures
JF - Composite Structures
SN - 0263-8223
ER -