Crack velocity dependent toughness in rate dependent materials

Landis, Chad M.; Pardoen, Thomas; Hutchinson, John W.

doi:10.1016/s0167-6636(00)00031-4

Cited by 91 publications

(49 citation statements)

References 33 publications

(39 reference statements)

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“…The epoxy then hardens linearly with a flow stress of 3s y at 100% equivalent plastic strain. This is a rather simplistic model for a glassy epoxy, but captures in at least a crude way the desired hardening response at large strain (Landis et al, 2000). It is worth noting that recent molecular dynamics simulations for an highly cross-linked polymer network confined between solid surfaces and subjected to a tensile loading generates a similar stress-strain curve, and that the simulation indicates that interfacial failure occurs in the region of rapid hardening as the polymer strands are pulled taut (Stevens, 2001).…”

Section: Iv3 Model Inputsmentioning

confidence: 98%

Physical Basis for Interfacial Traction-Separation Models

Moody¹

2002

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Many weapon components contain interfaces between dissimilar materials where cracks can initiate and cause failure. In recent years many researchers in the fracture community have adopted a cohesive zone model for simulating crack propagation (based upon traction-separation relations) Sandia is implementing this model in its ASCI codes. There is, however, one important obstacle to using a cohesive zone modeling approach. At the present time traction-separation relations are chosen in an ad hoc manner. The goal of the present work is to determine a physical basis for Traction-Separation (T-U)relations. This report presents results of a program aimed at determining the dependence of such relations on adhesive and bulk properties. The work focused on epoxy/solid interfaces, although the approach is applicable to a broad range of materials. Asymmetric double cantilevered beam and free surface film nanoindentation fracture toughness tests were used to generate a unique set of data spanning length scales, applied mode mixities, and yield (plastic) zone constraint. The crucial roles of crack tip plastic zone size and interfacial adhesion were defined by varying epoxy layer thickness and using coupling agents or special self-assembled monolayers in preparing the samples. The nature of the yield zone was probed in collaborative experiments run at the Advanced Photon Source. This work provides an understanding of the major phenomena governing polymer/solid interfacial fracture and identifies the essential features that must be incorporated in a T-U based cohesive zone failure model. We believe that models using physically based T-U relations provide a more accurate and widely applicable description of interface cracking than models using ad hoc relations. Furthermore, these T-U relations provide an essential tool for using models to tailor interface properties to meet design needs.

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Section: Iv3 Model Inputsmentioning

confidence: 98%

Physical Basis for Interfacial Traction-Separation Models

Moody¹

2002

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“…The main idea behind the present model was first suggested by Needleman (1987) in the context of inclusion debonding in heterogeneous materials. It was later applied to failure in homogeneous, elastic-plastic solids by Tvergaard and Hutchinson (1992) and to ratedependent materials by Landis et al (2000). More recently, it has been applied to cohesive failure in adhesive joints (Blackman et al, 2003b;Pardoen et al, 2005;Martiny et al, 2008;Salomonsson and Andersson, 2008;Cooper et al, 2009).…”

Section: Fundamentals Of the Modelmentioning

confidence: 99%

“…A somewhat similar model has been previously used to conduct parametric studies on the toughness of rate-independent materials (Tvergaard and Hutchinson, 1992), rate-dependent materials (Landis et al, 2000) and thin ductile layers joining semi-infinite elastic media (Tvergaard and Hutchinson, 1994). Also, the present model shares some common features with the one reported by Salomonsson and Andersson (2008), but in their work they set out to identify the cohesive zone model that would best represent the full adhesive layer.…”

Section: Introductionmentioning

confidence: 96%

A multiscale parametric study of mode I fracture in metal-to-metal low-toughness adhesive joints

et al. 2012

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The failure of adhesively-bonded joints, consisting of metallic adherends and epoxy-based structural adhesive with a relatively low toughness ∼200 J/m², has been studied. The failure was via quasistatic mode I, steady-state crack propagation and has been modelled numerically. The model implements a 'top-down approach' to fracture using a dedicated steady-state, finite-element formulation. The damage mechanisms responsible for fracture are condensed onto a row of cohesive zone elements with zero thickness, and the responses of the bulk adhesive and of the adherends are represented by continuum elements spanning the full geometry of the joint. The material parameters employed in the model are first quantitatively identified for the particular epoxy adhesive of interest, and their validity is verified by comparison with experimental results. The model is then used to conduct a detailed study on the effects of (a) large variations in the geometrical configuration of the different types of specimens and (b) the adherend stiffness on the predicted value of the adhesive fracture energy, . These numerical modelling results reveal that the adhesive fracture energy is a strong nonlinear function of the thickness of the adhesive layer, the other variables being of secondary importance in influencing the value of providing the adhesive does not contribute significantly to the bending stiffness of the joint. These results which fully agree with experimental observations are explained in detail by identifying, and quantifying, the different sources of energy dissipation in the bulk adhesive contributing to the value of . These sources are the locked-in elastic energy, crack tip plasticity, reverse plastic loading and plastic shear deformation at the adhesive/adherend interface. Further, the magnitudes of these sources of energy dissipation are correlated to the degree of constraint at the crack tip, which is quantified by considering the opening angle of the cohesive zone at the crack tip.

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“…This completes the set of equations that is solved iteratively by a procedure that was first suggested by Dean and Hutchinson [16], see also [17], and applied to the present model by Pardoen et al [8].…”

Section: General Descriptionmentioning

confidence: 99%