Sensitivity of double cantilever beam test to surface contamination and surface pretreatment

Wetzel, Michael; Holtmannspötter, Jens; Gudladt, H.‐J.; Czarnecki, Jan

doi:10.1016/j.ijadhadh.2013.06.002

Cited by 27 publications

(20 citation statements)

References 9 publications

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“…The body is subject to volume force f ∈ [L 2 (Ω)] d and g ∈ H 1/2 (Γ C ), g ≥ 0, is a gap function associating every point x ∈ Γ C with its distance to the rigid obstacle measured in the direction of the unit outer normal vector n(x). The body is (a) Load-displacement curve for different contamination concentrations, see [38] g-u n σ n (b) A nonmonotone adhesion law Further, ε(u) = 1 2 (∇u + ∇u T ) denotes the linearized strain tensor and σ(u) = C : ε(u) stands for the stress tensor, where C is the Hooke tensor, assumed to be uniformly positive definite with L ∞ coefficients. The boundary stress vector can be decomposed further into the normal, respectively, the tangential stress: σ n = σ(u)n · n, σ t = σ(u)n − σ n n.…”

Section: A Nonmonotone Boundary Value Problem From Delaminationmentioning

confidence: 99%

Coupling regularization and adaptive hp-BEM for the solution of a delamination problem

Ovcharova

Banz

2017

Numer. Math.

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In this paper, we couple regularization techniques with the adaptive hp-version of the boundary element method (hp-BEM) for the efficient numerical solution of linear elastic problems with nonmonotone contact boundary conditions. As a model example we treat the delamination of composite structures with a contaminated interface layer. This problem has a weak formulation in terms of a nonsmooth variational inequality. The resulting hemivariational inequality (HVI) is first regularized and then, discretized by an adaptive hp-BEM. We give conditions for the uniqueness of the solution and provide an a-priori error estimate. Furthermore, we derive an a-posteriori error estimate for the nonsmooth variational problem based on a novel regularized mixed formulation, thus enabling hp-adaptivity. Various numerical experiments illustrate the behavior, strengths and weaknesses of the proposed high-order approximation scheme.

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Section: A Nonmonotone Boundary Value Problem From Delaminationmentioning

confidence: 99%

Coupling regularization and adaptive hp-BEM for the solution of a delamination problem

Ovcharova

Banz

2017

Numer. Math.

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“…For the repair technician, surface treatment should be regarded as a key factor to influence the reliability and robustness of the process. Unfortunately, in reality, surface FIGURE 7 Adhesive fracture energy release rate for G1C fracture toughness test (a) and single lap shear strength (b) of clean, contaminated, and ultrasonic primer treated CFRP samples [35].…”

Section: Fabrication and Automation Of Reliable Bonded Composite Repamentioning

confidence: 99%

On the Fabrication and Automation of Reliable Bonded Composite Repairs

Holtmannspötter¹,

Czarnecki²,

Feucht³

et al. 2014

The Journal of Adhesion

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“…[2] Research shows that the fracture surface of DCB test coupons show adhesive failure when defects such as pre-bond contamination, pre-bond moisture and uncured adhesive are present at the bond line. [3,4,5] As a consequence, fracture toughness values under opening mode (G IC ) significantly decrease, which is a direct result from the crack growing at the interface instead of inside the adhesive layer (cohesive failure-good adhesion quality). [6,7] The same studies also show that neither ultrasonic C-scan nor X-ray tomography are able to detect those defects prior to testing.…”

Section: Introductionmentioning

confidence: 99%

The use of acoustic emission and composite peel tests to detect weak adhesion in composite structures

Freitas

Zarouchas

Poulis

2018

The Journal of Adhesion

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Adhesive bonding is one of the most promising joining technologies for composite aircraft. However, to comply with current aircraft certification rules, current safety-critical bonded joints, in which at least one of the interfaces requires additional surface preparation, are always used in combination with redundant mechanical fasteners, such as rivets and bolts. This lack of trust in bonded structures is mostly linked to the fear of lack of adhesion or a "weak bond".The aim of this paper is to tackle this challenge by assessing the ability to use composite peel tests and acoustic emission (AE) technique to assess adhesion quality and distinguish a good bond quality from a "weak bond".Composite Bell Peel (CBP) tests and Double-CantileverBeam (DCB) tests were performed on contaminated and noncontaminated CFRP bonded specimens. The results show that peel strength drops significantly at the location of the contaminated interface that has led to weak adhesion, as a result from adhesive failure. The AE signals obtained during DCB tests show different features for cracks growing at the interface ("weak bonds") and inside the adhesive layer (cohesive failure). In addition to this, scattering of the AE signals were observed in the contaminated specimens with "weak bonds". ARTICLE HISTORY

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Sensitivity of double cantilever beam test to surface contamination and surface pretreatment

Cited by 27 publications

References 9 publications

Coupling regularization and adaptive hp-BEM for the solution of a delamination problem

Coupling regularization and adaptive hp-BEM for the solution of a delamination problem

On the Fabrication and Automation of Reliable Bonded Composite Repairs

The use of acoustic emission and composite peel tests to detect weak adhesion in composite structures

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