Validation of continuum damage approach in open-hole carbon-epoxy laminates

This paper deals with modelling of damage initiation and propagation in carbon/epoxy open-hole coupons laminates. Finite element based continuum damage approach was selected for modelling coupons.

In a first approach, laminates were modelled by a single shell element per thickness. In a second approach complexity of the model was increased by modelling each lamina independently with solid elements and interlaminar damage or delamination between adjacent laminas with cohesive element. Both models approaches were implemented in Ls-Dyna explicit finite element code. Continuum damage law of a lamina was modelled by a umat user subroutine and delamination was modelled by Ls-dyna cohesive law and elements.

For validating the approaches tensile test in open-hole coupons were carried out at universal testing machine. Three different ply-orientation were used during the exercise [90,45,0,-45]s, [0,90,0,90]s and [45,-45,45,-45]s. For validating approaches numerical tensile force–displacement curve were compared with experimental curves. Moreover, thermoelastic Stress Analysis (TSA) technique was considered for the identification of damage initiation. TSA results are compared to numerical results. For TSA experimental temperature were recorded by Flir SC5500 high performance IR camera.