A straightforward method to obtain the cohesive laws of bonded joints under mode I loading

Abstract

Keywords:Bonded joints Cohesive laws Mode I Double cantilever beam test a b s t r a c t A simple procedure to measure the cohesive laws of bonded joints under mode I loading using the double cantilever beam test is proposed. The method only requires recording the applied loaddisplacement data and measuring the crack opening displacement at its tip in the course of the experimental test. The strain energy release rate is obtained by a procedure involving the Timoshenko beam theory, the specimen's compliance and the crack equivalent concept. Following the proposed approach the influence of the fracture process zone is taken into account which is fundamental for an accurate estimation of the failure process details. The cohesive law is obtained by differentiation of the strain energy release rate as a function of the crack opening displacement. The model was validated numerically considering three representative cohesive laws. Numerical simulations using finite element analysis including cohesive zone modeling were performed. The good agreement between the inputted and resulting laws for all the cases considered validates the model. An experimental confirmation was also performed by comparing the numerical and experimental load-displacement curves. The numerical load-displacement curves were obtained by adjusting typical cohesive laws to the ones measured experimentally following the proposed approach and using finite element analysis including cohesive zone modeling. Once again, good agreement was obtained in the comparisons thus demonstrating the good performance of the proposed methodology.

Predicting the strength of adhesively bonded joints of variable thickness using a cohesive element approach

“…The cohesive law is obtained through differentiation of the relationship between G I and the crack opening displacement. This method has been implemented numerically for a variety of different cohesive laws and shows excellent agreement with experimental measurements [24,25].…”

“…An alternative approach to obtain the mode I cohesive laws of bonded joints has been proposed [21][22][23][24] and presented for composite bonded joints by Dias et al [25]. This method utilises the measurement of the strain energy release rate, G I , expressed as a function of the crack opening displacement as measured through a novel digital image correlation technique using a standard double cantilever beam test.…”

The Effect of Outer Diameter of Multi-Walled Carbon Nanotubes on Fracture Behavior of Epoxy Adhesives

“…The Cohesive Zone Model (CZM) has gained remarkable attention in damage modeling of di erent materials and problems. This model was successfully employed to study damage behavior of adhesive and composite structures under various loadings, such as quasi-static [15], fatigue [16], and creep [17] loading.…”

Analysis of the metal adhesively bonded double cantilever beam specimen

“…In spite of the above questions regarding the meaningfulness of the mode I fracture energy, the DCB specimen has been increasingly used to evaluate the traction-separation law of the adhesive [17][18][19][20][21][22][23][24][25]. The method employed, often designated as "direct", reqAccurate methods to compute J I , which may in turn require measurements of load-point crack-tip rotations [19,20,25], or simply application of beam theory based data reduction schemes [21][22][23][24] similar to those used for delamination of composites [16,26,27].…”