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

Abstract

In this paper a methodology to model a GFRP adhesive connections by using an imperfect soft interface model is presented. The model based on Kachanov's theory considered a cracked thin adhesive. Within this framework, the mechanical properties and the initial damage (diffuse initial cracks) of the adhesive layer has been experimentally evaluated. With a modified Arcan system, static tests were performed on adhesively bonded assemblies in tensile and shear solicitation mode considering three different adhesive thicknesses. The experimental results highlighted how the thickness of adhesive influences the mechanical strength and stiffness of the bonded connection. CT-scans were performed to measure the porosity rate in the adhesive layer. Furthermore, the excellent comparison of numerical and experimental data of an adhesive GFRP bonded connections allow us to consider the imperfect soft interface model proposed as highly competitive to evaluate complex structure performance in civil engineering context. A parametric analysis has been proposed to provide a formula able to describe the full response of the structure at varying adhesive property.

A micromechanical model of a hard interface with micro-cracking damage

“…etc.) whose variation depends macroscopically on kinematic variables [6][7][8][9][10][11][12][13][14][15]. Numerical soft interface models, in the framework of the finite element theory, generally use cohesive zone models (CZM) based on traction-separation laws of various shapes, to describe cohesive and adhesive failure [16][17][18][19][20][21][22].…”

“…1). This strategy has already been successfully used to describe the mechanics of thin elastic layers in adhesive-like problems and contact problems [13,15,30,31]. Moreover, it has been identified as a sound alternative to the classical cohesive zone models, principally because imperfect interface models allow to consider the physics of the adhesives in terms of geometrical (thickness, surface roughness), mechanical (anisotropy, non-linearity) and damage properties.…”

“…Particularly, the adoption of a generalized cracks density [38] 3 allows to by-pass the geometrical definition of the cracks, which is possible only for circular and regular cracks [32], and as a matter of fact it extends the generality of the proposed interface model to any regular and irregular cracks shape. It should also be noted that the generalized microcracks density can be measured postmortem by X-ray micro-tomography [15]. The evolutive character of the micro-cracking damage is described by introducing a new evolution law of the generalized cracks density.…”

A Model of Damage for Brittle and Ductile Adhesives in Glued Butt Joints

“…In the lower part of the tube-to-tube butt joint below the adhesive, for x 3 ≤ h, the displacement field is still given by (2). In (7), the jumps [[u i ]], i = 1, 2, 3, have to be chosen in order to satisfy the transmission conditions (3) and (4).…”

“…Within the last decades, adhesive bonding became a very common assembly technique in many industrial sectors, such as aeronautical (e.g., in composite aircraft to bond the stringers to fuselage and wing skins to stiffen the structures against buckling [1]), civil (e.g., in glass-fiber-reinforced polymer pultruded beams [2] or in carbon-fiber-reinforced polymer beams [3]), automotive (e.g., in both closures and structural modules [4]), and biomedical engineering (to fix implants in bone tissue in orthopedic or dentistry surgery [5]), as an alternative to conventional joining techniques, such as welding and riveting [6]. Adhesive bonding provides several advantages, including reduced stress concentrations, higher corrosion resistance, water tightness, and the ability to join materials with dissimilar properties.…”