Estimation of failure load of composite bonded joints using 1D and 2D FE analysis and the mathematical equation of strain and bond energy in the adhesive layer

Adhesively bonded composite (ABC) joints used in the composite structures are modeled using 1D and 2D elements to generate the finite-element mesh. The present modeling technique has captured the overall structural behavior of ABC joints precisely. The analytical study proposed a novel failure criterion of ABC joints after understanding the structural behavior of joints through the modeling approach. A failure criterion developed based on the principle of conservation of energy stored within the adhesive layer by virtue of its allowable strength properties and consumed by applying stress per a unit load. The ultimate failure load of joints of popular configurations is estimated based on the principle of conservation of energy. The 1D-2D finite-element modeling approach has revealed the presence of a new form of mechanical energy named as the Bond energy concealed within the adhesive layer. A new failure mechanism and their modes are explained through the novel failure criterion. The numerical value of Bond energy is calculated by using a peculiar mathematical relationship between the allowable shear strength property and the Young's modulus of the adhesive layer. The ultimate failure load estimated by the novel failure criterion is compared with that of third-party experimental results and found fair agreement of 1-11% difference, which is acceptable with appreciation.