Experimental estimation of the mechanical and fracture properties of a new epoxy adhesive

Monteiro, Joaquim; Campilho, R.D.S.G.; Marques, E.A.S.; Silva, Lucas F. M. da

doi:10.1186/s40563-015-0056-y

Cited by 22 publications

(7 citation statements)

References 21 publications

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“…where l crack is the crack length and B is the width of the model [23]. To determine the energy release rate G IC for the increment n cut the corresponded crack length l crack is measured.…”

Section: Verificationmentioning

confidence: 99%

A mode-dependent energy-based damage model for peridynamics and its implementation

Willberg

Wiedemann

Rädel

2019

J. Mech. Mater. Struct.

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The mathematical modeling of failure mechanisms in solid materials and structures is a long standing problem. In recent years, Peridynamics has been used as a theoretical basis for numerical studies of fracture initiation, evolution and propagation. In order to investigate damage phenomena numerically, suitable material and damage models have to be implemented in an efficient numerical framework. This framework should be highly parallelizable in order to cope with the computational effort due to the high spatial and, depending on the problem, temporal resolution required for high accuracy. The open-source peridynamic framework Peridigm offers a computational platform upon which new developments of the peridynamic theory can be implemented. Today, isotropic material models and a very simple damage model are implemented in Peridigm.This paper proposes three energy-based damage criteria. The implementation approach as well as the extension of Peridigm with these physically motivated models is described. The original criterion of Foster et al.[1] is adapted for ordinary state based material. The other two criteria utilize the decomposition of peridynamic states in isotropic and deviatoric parts to account for the failure-mode dependency.The original criterion is verified by the numerical simulation of two mechanical problems. At first, a virtual double cantilever beam (DCB) experiment is performed to determine the energy release rate. This value is the fundamental material property required for the proposed criteria. Additionally, the DCB problem is then used to investigate the convergence of the numerical scheme implemented in Peridigm. In a second step, a model of a plate with a cylindrical hole under tensile loading is compared with an extended finite element method (XFEM) solution. Results of both numerical solutions are in good agreement. Finally, a fiber reinforced micro structure model is used to analyze the effect of the different criteria to the damage initiation and crack propagation under a more complex loading condition.

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Section: Verificationmentioning

confidence: 99%

A mode-dependent energy-based damage model for peridynamics and its implementation

Willberg

Wiedemann

Rädel

2019

J. Mech. Mater. Struct.

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“…This reduction in R-curve due to constraint has been quantified for a thin metallic sandwich layer by Tvergaard and Hutchinson (1996). Typically, the ratio of steady-state fracture toughness to the initiation value for polymeric adhesives in bulk form is of magnitude 1.5 for most epoxies 1 , acrylic, and polyurethane-based adhesives (Blackman et al, 2003;Martiny et al, 2012;Banea et al, 2014;Monteiro et al, 2015;Lopes et al 2016;Bonaldo et al, 2018). The degree of R-curve is reduced when the adhesive is in the form of a thin layer between elastic substrates, as explained by Tvergaard and Hutchinson (1996).…”

Section: Introductionmentioning

confidence: 99%

Tensile fracture of an adhesive joint: the role of crack length and of material mismatch

Loock

Thouless

Fleck

2019

Journal of the Mechanics and Physics of Solids

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The tensile strength of an adhesive joint is predicted for a centre-cracked elastic layer, sandwiched between elastic substrates, and subjected to remote tensile stress. A tensile cohesive plastic zone, of Dugdale type, is placed at each crack tip, and the cohesive zone is characterised by a finite strength and a finite toughness. An analytical theory of the fracture strength is developed (and validated by finite element simulations). The macroscopic strength of the adhesive joint is determined as a function of the relative magnitude of crack length, layer thickness, plastic zone size, specimen width and elastic modulus mismatch between layer and substrates. Fracture maps are constructed to reveal competing regimes of behaviour. The maps span the full range of behaviour from a perfectly brittle response (with no crack tip plasticity) to full plastic collapse. When the sum of crack length and cohesive zone length is less than 0.3 times the layer height, the effect of elastic mismatch between substrate and adhesive layer has only a minor influence upon the macroscopic fracture strength. For this case, the cracked adhesive layer behaves as a centre-crack in an infinite solid made from adhesive, and a transition from toughness control to strength control occurs when the crack length is comparable to that of the cohesive zone length. Alternatively, when the sum of crack length and cohesive zone length exceeds 0.3 times the layer height, the elastic mismatch plays a major role; again there is a transition from toughness control to strength control, but it occurs at a ratio of crack length to layer thickness that depends upon both the elastic mismatch and the ratio of cohesive zone length to layer height. The study also highlights the importance of a structural length scale in the form of layer height times modulus mismatch: this scale is on the order of 1 metre when the layer height equals one millimetre and the elastic modulus of the 2 substrate is one thousand times that of the adhesive layer. The in-plane structural dimensions (including crack length) must exceed this structural dimension in order for a remote K-field to exist within the substrate. Experimental validation of the cohesive zone approach is achieved by measuring the sensitivity of fracture strength to crack length and layer height for a centrecracked strip made from cellulose acetate layer, sandwiched between aluminium alloy substrates.

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“…It is worth mentioning that there was no damage between the adhesive and the CFRP in the experiment. Please refer to Monteiro et al [27] for more details of the axial crushing test on adhesively bonded thin-walled beam.…”

Section: Resultsmentioning

confidence: 99%

“…Meanwhile, interlaminar properties of IM7/ 8552 prepreg and material parameters of structural adhesive SikaPower 4720 necessary for subsequent FE modeling are depicted in Table 3, where Normal Failure Stress (NFLS) and Shear Failure Stress (SFLS) are LS-DYNA terminology representing the failure strength in normal and shear directions, respectively. They can be determined through bulk specimen tensile test and thick adherend shear test (TAST) [25,27]. The material parameters obtained from the experimental process can be found in [25].…”

Section: Materials Propertiesmentioning

confidence: 99%

Geometry optimization on the cross section of adhesively bonded thin-walled composite beam subjected to axial crushing load

Xiao,

Ye,

Hou

et al. 2024

Academia Materials Science

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Adhesive bonding is widely used in structural connection of composite components due to its capacity to effectively avoid inducing stress concentration and damage in composite components. This work applies a design optimization methodology on the geometry of cross section and ply thickness in adhesively bonded CFRP (carbon fiber-reinforced plastic), hat-shaped, thin-walled beam in automobiles to achieve car body lightweight design. A multi-objective and multi-constraint design optimization problem was formulated to find the optimum key cross-section size and ply thickness of the hat thin-walled beam. The minimum total material cost and maximum energy absorption (EA) during the axial crushing test of the CFRP beam were selected as the optimization objectives. The non-dominated sorting genetic algorithm II (NSGA-II) was introduced to search for global optimum solution, and radial basis function (RBF) approximations for the objective functions were applied to reduce the computational cost. It was revealed that EA increased by 8.28%, while the total weight and cost decreased by 3.14% and 3.23%, respectively, and can thus provide a guidance in vehicle composite component design.

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Experimental estimation of the mechanical and fracture properties of a new epoxy adhesive

Cited by 22 publications

References 21 publications

A mode-dependent energy-based damage model for peridynamics and its implementation

A mode-dependent energy-based damage model for peridynamics and its implementation

Tensile fracture of an adhesive joint: the role of crack length and of material mismatch

Geometry optimization on the cross section of adhesively bonded thin-walled composite beam subjected to axial crushing load

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