Theoretical development and experimental validation of a thermally dissipative cohesive zone model for dynamic fracture of amorphous polymers

Bjerke, Todd W.; Lambros, John

doi:10.1016/s0022-5096(02)00145-x

Cited by 39 publications

(50 citation statements)

References 25 publications

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“…Parametric investigations probing these phenomena, as well as effects of choice of various traction-separation curve shapes (cf. Bjerke and Lambros, 2003) and coupling schemes between normal and tangential traction-separation relations (Ortiz and Pandolfi, 1999;Espinosa and Zavattieri, 2003b) are reserved for future work. …”

Section: Fracture Modelingmentioning

confidence: 99%

Dynamic plasticity and fracture in high density polycrystals: constitutive modeling and numerical simulation

Clayton

2005

Journal of the Mechanics and Physics of Solids

172

110

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Section: Fracture Modelingmentioning

confidence: 99%

Dynamic plasticity and fracture in high density polycrystals: constitutive modeling and numerical simulation

Clayton

2005

Journal of the Mechanics and Physics of Solids

172

110

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“…The influence of the shape of the cohesive law has been examined recently for quasi-static crack growth in elasto-plastic materials by Scheider and Brocks [9] and Li and Chandra [10], for quasi-static growth in brittle materials by Elices et al [11], and for dynamic crack growth in brittle polymers by Bjerke and Lambros [12]. In the latter study, a single layer, thermally dissipative cohesive model was employed which was found to be in good agreement with experimental observation for low crack propagation rates.…”

Section: On the Importance Of The Shape Of The Traction-separation Lawmentioning

confidence: 99%

The prediction of dynamic fracture evolution in PMMA using a cohesive zone model

Murphy

2005

Engineering Fracture Mechanics

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A cohesive zone model was used in conjunction with the finite volume method to model the dynamic fracture of single edge notched tensile specimens of PMMA under essentially static loading conditions. In this study, the influence of the shape of the cohesive law was investigated, whilst keeping the cohesive strength and separation energy constant. Cohesive cells were adaptively inserted between adjacent continuum cells when the normal traction across that face exceeded the cohesive strength of the material. The cohesive constitutive law was therefore initially rigid, and the effective elasticity of the material was unaltered prior to insertion of the cohesive cells. Notch depths ranging from 2.0 mm to 0.1 mm were considered. The numerical predictions were compared with experimental observations for each notch depth and excellent qualitative and quantitative agreement was achieved in most cases. Following an initial period of rapid crack tip acceleration up to terminal velocities well below the Rayleigh wave speed, subsequent propagation took place at a constant rate under conditions of increasing energy flux to an expanding process region. In addition, attempted and successful branching was predicted for the shorter notches. It was found that the shape of the cohesive law had a significant influence on the dynamic fracture behaviour. In particular, the value of the initial slope of the softening function was found to be an important parameter. As the slope became steeper, the predicted terminal crack speed increased and the extent of the damage decreased.

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“…Bjerke and Lambros (2003) did recognise the importance of heat generation within the craze active layer. They also noted, as Godovsky (1992) had done, that rupture of a stressed craze fibril can release strain energy and dissipate it during recoil.…”

mentioning

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Adiabatic decohesion in a thermoplastic craze thickening at constant or increasing rate

Leevers

Godart

2008

Journal of the Mechanics and Physics of Solids

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When a crack in a thermally non-diffusive material is impact loaded -or propagates at high speed -a cohesive process which resists slow crack extension may itself cause decohesion by adiabatic heating. By assuming that decohesion ultimately occurs by low-energy disentanglement within a melt layer of critical thickness, the fracture resistance of craze-forming crystalline polymers can be estimated quantitatively. Previous estimates used a simple, thermomechanically linear representation of craze fibril drawing. This paper presents a more physically realistic, numerical formulation, and demonstrates it for constant craze thickening rate (as imposed by an ideal full-notch tension test) and for linearly increasing thickening rate (as at the tip of an impact-loaded or rapidly propagating crack). For a linear material, the numerical formulation gives results which asymptotically approach those from analytical solutions, as craze density approaches zero. In more realistic model polymers, the enthalpy of fusion increasingly delays decohesion as impact speed increases, although the temperature distribution of an endotherm appears to have little effect. Increasing molecular weight, heuristically associated with decreasing craze density and increasing structural dimension, increases the predicted impact fracture resistance. In every case, fracture resistance passes through a minimum as impact speed increases. The conclusions encourage the use of impact fracture tests, and discourage the use of the full-notch tension test, to assess the dynamic fracture resistance of a craze-forming polymer.Key words: Crack propagation and arrest, dynamic fracture, fracture mechanisms, fracture toughness, polymeric material Nomenclature β Thermomechanical efficiency ∆H Enthalpy

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Theoretical development and experimental validation of a thermally dissipative cohesive zone model for dynamic fracture of amorphous polymers

Cited by 39 publications

References 25 publications

Dynamic plasticity and fracture in high density polycrystals: constitutive modeling and numerical simulation

Dynamic plasticity and fracture in high density polycrystals: constitutive modeling and numerical simulation

The prediction of dynamic fracture evolution in PMMA using a cohesive zone model

Adiabatic decohesion in a thermoplastic craze thickening at constant or increasing rate

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