Measurement of interface cohesive stresses and strains evolutions with combined mixed mode crack propagation test and Backface Strain Monitoring measurements

Abstract

a b s t r a c tA Mixed Mode Bending (MMB) test is used to study the fracture process of an adhesively bonded specimen. Simple Beam analysis is proposed to estimate the Strain Energy Released Rate (SERR) from the evolution of specimen compliance. The effect of interface compliance on the process zone extension and specimen deformation is studied. Additionally, the Backface Strain Monitoring (BSM) technique is used to probe the peel and shear cohesive stresses along the bondline. With a simple analysis, a systematic procedure is proposed to evaluate the cohesive stresses as well as the peel and shear strain evolutions in the vicinity of the crack tip position during crack propagation experiment under mixed mode conditions.

Using digital image correlation to automate the measurement of crack length and fracture energy in the mode I testing of structural adhesive joints

“…Another strategy followed has been to use crack length independent test specimens such as the tapered double cantilever beam (TDCB) for mode I [14] (some studies report that the TDCB test may be invalid for testing ductile adhesives [3]), the tapered end notched flexure (TENF) specimen for mode II [15], the DCB specimen loaded with pure bending moments [16], and the J-integral methods [17,18]. However, efforts continue in the field to develop alternative techniques for crack length measurements, such as by using strain gauge sensors [19], optical tracking [20], luminescence [21] and acoustic emission [22] techniques. These methods have the potential to become more accurate than visual inspection, as they can more precisely track the crack tip and potentially include the effects due to material damage.…”

Modelling of a GFRP adhesive connection by an imperfect soft interface model with initial damage

“…Moreover, adhesively bonded joints offer many advantages for the design of structures. But to improve the confidence that currently limits the use of this technology, several authors try to develop experimental [15] [16] [17] or numerical [18] [19] [20] approaches.…”

Mode I cohesive zone model parameters identification and comparison of measurement techniques based on uncertainty estimation

“…Adherends' deformation can also be measured using optical [17] or resistive [18] strain gauges. As it enable a precise location of the crack tip but can also be used for the direct identification of the CZM through the differentiation of the backface strain signal evolution [19]. Direct inversion techniques have also been proposed for the CZM reconstruction from the experimental data obtain with BSM and J() techniques.…”