Assessment of interface failure behaviour for brittle adhesive using the three-point bending test

Abstract

ARTICLEINFO AB STRACT Adhesive failure Threepo int bending test Coupled criteri on Macro-element lnterfacial pr oper ties In the framework of the adhesive bonding, the assessment of interfacial properties has an essential role in determining the adhesive joints' global responses. Various surface preparations are available for each type of metallic substrate. There are plency of tests widely used for mechanical characterisation to determine the ad hesive properties and few tests to assess interfacial properties. For such a case, a specific three-point bending test can be applied to examine the interactions between adhesive and substrate. On the other hand, a direct com parison of the critical force is not always possible because of geometrical incompatibility. A practical solution for the last issue is applying a coupled stress-energy criterion ( CC ) since the interface propenies are independent of the substrate thickness. Hence, CC and the macro-elen1ent technique were applied to determine the interfacial properties using an aluminium alloy 2024-T3 as substrate and the adhesive DGEBA/DETA TM under many preparation conditions. As a result, the three-point bending test's overall behaviour was established in terms of interface strength (adherence), including incren1ental energy release rate and critical stress. Thus, this paper can be read as the first work towards the ability to predict the interface failure in the fran1e of three-point bending test using different geometries. In conclusion, the occurrence of an adhesive or cohesive failure and the unstable or a stable failure propagation of the bonded joints were sorted and classified as a function of interface properties.

On the effect of roughness parameters on adherence using the three-point bending test (ISO 14679:1997)

“…Finally, the relation between Fe and Sc is constructed (see Figure 11), as previously described by Birro et al (2021). l 13 l Thus, the result obtained for the abraded substrate is in agreement with the typical curve obtained via pure chemical treatment.…”

“…Nevertheless, a düferent failure mechanism is obtained during the crack propagation -interfacial failure propagation for a low rough ness instead of an interphasial failure propagation for higher roughness. Therefore, a new fracture propagation mechanism is only reached when a low F e is obtained experimentally, as previously constated by Birro et al (2021). [I 4 l Thus, the experimental and statistical studies reveal that roughness can directly impact the critical length of failure initiation as well as the mechanism of fracture propagation when a low roughness is reached, even though ail failure initiations are adhesive and independent in terms of roughness com prised from 58� R a �2120 nm.…”

“…Nevertheless, when the critical force becomes lower, the points seem more scattered when compared with the tendency line. This fact can be explained by the general failure initiation described by Birro et al (2021). The small round area is no longer present for lower forces, nor the remaining tetrahedron shaped adhesive.…”

“…In addition, Birro et al (2021). l 1 3l demonstrated that the overall behavior of the three-point bending specimens can be directly related to failure initiation area (S c ): stable propagation is expected for high Sc, whereas an unstable propagation is expected for low Sc.…”

Comparison of the Bending Behavior of Cylindrically Shaped Lattice Specimens with Radially and Orthogonally Arranged Cells Made of ABS

“…The porous samples made from ABS material used within the research showed mostly brittle behavior. Some of them, including the R_57 in Figure 10, showed a sudden drop in applied force after elastic deformation, which can be connected with the theory of failure propagation [57]. Since the cellular structures were studied within the research, it can be said that the type of failure propagation (fast or slow, along the cell boundaries or through the pores, smooth or stepwise, etc.)…”