Analytical and experimental investigations of crack propagation in adhesively bonded joints with the Mixed Mode Bending (MMB) test Part II: Investigation of cohesive stresses distribution with backface strain monitoring

In this work, a finite-element formulation for modeling mixed-mode delamination in layered structures, consisting of two-node Timoshenko beam finite elements with quadratic linked interpolation and corresponding 4-node interface elements is presented and compared to a more common approach where linear Lagrange interpolation is used. The principal novelty of the proposed approach is that the vertical displacements of the beam elements, as well as the transversal relative displacements of the interface elements, are interpolated using a quadratic linked interpolation that also takes into account the nodal cross-sectional rotations of the beam elements. At the same time, the axial displacements and cross-sectional rotations are interpolated using linear Lagrange polynomials. A bilinear cohesive zone model is embedded in the interface finite elements for delamination modes I and II. Numerical analyses based on the examples from the literature with metal joints show that the formulation with quadratic linked interpolation improves the convergence and robustness of the solution with respect to the approach with linear interpolation. On the other hand, in case of composites with stiff adhesives this formulation exhibits a peculiar behavior with spurious oscillations of the normal interface tractions that leads to a poor performance in mode-I and mixed-mode tests. This problem can be easily solved by canceling the quadratic term in the interpolation function and using the standard Lagrange interpolation in such cases.

show abstract

“…Configuration of the (A) ENF test from Reference 47 and (B) MMB test from Reference 48, with the corresponding geometrical properties…”

Section: Numerical Examplesmentioning

confidence: 99%

“…Comparison of the performance of (TB2+BINT4)L with (TB2+BINT4)Q models in the MMB test from Reference 48 for (A)

{L}_e=5

mm and (B)

{L}_e=2

mm…”

Section: Numerical Examplesmentioning

confidence: 99%

Mixed‐mode delamination of layered structures modeled as Timoshenko beams with linked interpolation

Ranjbar

Škec

Jelenić

et al. 2022

Numerical Meth Engineering

View full text Add to dashboard Cite

show abstract

“…The MMB test excels the other tests by enabling to vary the mixed-mode ratio up to pure tension and shear, and is often a preferred choice to build fracture envelopes of adhesives with significant data points. 13,14 The SLB specimen, developed by Yoon and Hong, 15 is relatively easy to fabricate and test in three-point bending. The geometry is similar to that of the DCB and ENF tests, but one of the adherends is shorter at the cracked portion, such that the bending load induces both tension and shear at the crack tip due to absence of support to the lower adherend.…”

Section: Introductionmentioning

confidence: 99%

Numerical analysis of the mixed-mode fracture of bonded joints depending on the adhesive thickness

Macedo

Campilho

Silva

et al. 2022

Proceedings of the Institution of Mechanical Engineers, Part E:

View full text Add to dashboard Cite

The mixed-mode strength of bonded joints can be predicted by techniques such as cohesive zone models (CZM), which requires the estimation of the adhesive strength and fracture toughness ( GC). Under the scope of fracture properties, the tensile and shear fracture toughness ( GIC and GIIC, respectively) and the corresponding mixed-mode behaviour are particularly relevant. Moreover, these parameters highly depend on the adhesive thickness ( tA), making it relevant to validate and propose CZM laws for bonded joint design. This work numerically addressed the tA influence on the mixed-mode fracture process of adhesive joints. For this purpose, single-leg bending (SLB) test experimental data was used, considering joints with composite adherends and a ductile adhesive, and tA from 0.1 to 2.0 mm. A numerical CZM analysis was performed, including the experimental and numerical load-displacement ( P- δ) curves’ comparison for validation, followed by the CZM law estimation and fracture envelope validation, for all tA. The effect of the different CZM parameters on the results was finally evaluated. Overall, it was possible to numerically ascertain the tA effect on the fracture behaviour of adhesive joints and to propose a numerical technique for mixed-mode bonded joint analysis.

show abstract

A hybrid experimental and numerical technique for evaluating residual strains/stresses in bonded lap joints

Hassan

Kundurthi

Vattathurvalappil

et al. 2021

Composites Part B: Engineering

View full text Add to dashboard Cite

Analytical and experimental investigations of crack propagation in adhesively bonded joints with the Mixed Mode Bending (MMB) test Part II: Investigation of cohesive stresses distribution with backface strain monitoring

Cited by 8 publications

References 41 publications

Mixed‐mode delamination of layered structures modeled as Timoshenko beams with linked interpolation

Mixed‐mode delamination of layered structures modeled as Timoshenko beams with linked interpolation

Numerical analysis of the mixed-mode fracture of bonded joints depending on the adhesive thickness

A hybrid experimental and numerical technique for evaluating residual strains/stresses in bonded lap joints

Contact Info

Product

Resources

About