The Effect of Algorithm Form on Deformation and Instability in Tension

Goldthorpe, B.D.; Church, P.

doi:10.1051/jp4:19973128

“…The author acknowledges the contributions of Barry GoldGoldthorpe et al [10] have shown in analytic studies of plastic thorpe, Tony Andrews, and Peter Gould, DERA, in the develdeformation and instability that once localization occur, it opment of the constitutive algorithms, and Alan Butler, for rapidly leads to failure. In the present study, once failure is sectioning the target plates and plugs.…”

Section: Discussionmentioning

confidence: 96%

Simulation of shear plugging through thin plates using the GRIM eulerian hydrocode

Church¹,

Cornish²,

Cullis³

et al. 2000

Metall Mater Trans A

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Ballistic experiments have been performed using aluminum spheres against 10-mm rolled homogenous armour (RHA), MARS270, MARS300, and titanium alloy plates to investigate the influence of the plugging mechanism on material properties. The experiments have measured the threshold for plug mass and velocity as well as the recovered aluminum sphere mass over a range of velocities. Some of the experiments have been simulated using the in-house second generation Eulerian hydrocode GRIM. The calculations feature advanced material algorithms derived from interrupted tensile testing techniques and a triaxial failure model derived from notched tensile tests over a range of strain rates and temperatures. The effect of mesh resolution on the results has been investigated and understood. The simulation results illustrate the importance of the constitutive model in the shear localization process and the subsequent plugging phenomena. The stress triaxiality is seen as the dominant feature in controlling the onset and subsequent propagation of the crack leading to the shear plug. The simulations have demonstrated that accurate numerics coupled with accurate constitutive and fracture algorithms can successfully reproduce the observed experimental features. However, extrapolation of the fracture data leads to the simulations overpredicting the plug damage. The reasons for this are discussed.

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“…The author acknowledges the contributions of Barry Gold-Goldthorpe et al [10] have shown in analytic studies of plastic thorpe, Tony Andrews, and Peter Gould, DERA, in the develdeformation and instability that once localization occur, it opment of the constitutive algorithms, and Alan Butler, for rapidly leads to failure. In the present study, once failure is sectioning the target plates and plugs.…”

Section: Discussionmentioning

confidence: 99%

Simulation of shear plugging through thin plates using the GRIM Eulerian hydrocode

Church¹,

Cornish²,

Cullis³

et al. 2000

Metall Mater Trans A

Self Cite

1

0

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Ballistic experiments have been performed using aluminum spheres against 10-mm rolled homogenous armour (RHA), MARS270, MARS300, and titanium alloy plates to investigate the influence of the plugging mechanism on material properties. The experiments have measured the threshold for plug mass and velocity as well as the recovered aluminum sphere mass over a range of velocities. Some of the experiments have been simulated using the in-house second generation Eulerian hydrocode GRIM. The calculations feature advanced material algorithms derived from interrupted tensile testing techniques and a triaxial failure model derived from notched tensile tests over a range of strain rates and temperatures. The effect of mesh resolution on the results has been investigated and understood. The simulation results illustrate the importance of the constitutive model in the shear localization process and the subsequent plugging phenomena. The stress triaxiality is seen as the dominant feature in controlling the onset and subsequent propagation of the crack leading to the shear plug. The simulations have demonstrated that accurate numerics coupled with accurate constitutive and fracture algorithms can successfully reproduce the observed experimental features. However, extrapolation of the fracture data leads to the simulations overpredicting the plug damage. The reasons for this are discussed.

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“…Goldthorpe's neck analysis recognises that at high strains the stress distribution in the neck of a tensile sample has to be constrained [2]. Equation (3) shows Goldthorpe's final definition relating load (F) to uniaxial flow stress (σ).…”

Section: Materials and Fracture Models 21 Analytic Necking Solutionsmentioning

confidence: 99%

Scale effects in necking

Dunnett

¹

,

Balint

²

,

MacGillivray

³

et al. 2012

EPJ Web of Conferences

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Abstract. Geometrically similar specimens spanning a scale range of 100:1 are tested quasi-statically to failure. Images of neck development are acquired using optical means for large specimens, and in-situ scanning electron microscope testing for small specimens, to examine the dependence of neck geometry on a broad range of specimen sizes. Size effects typically arise when the smallest specimen dimension is on the order of a microstructural length (e.g. grain size, dislocation mean free path, etc.), or in the presence of significant plastic strain gradients, which increase the density of geometrically necessary dislocations. This study was carried out for the purpose of investigating scale dependence in models used for predicting dynamic deformation and damage to very high strains for ballistic impact applications, such as the Goldthorpe path-dependent failure model, which includes temperature and strain-rate dependence but does not account for specimen size or a dependence on microstructural lengths. Although the experiments show that neck geometry does not exhibit a clear dependence on specimen size across the range of length scales tested, the statistical variation due to microstructural variations was found to increase monotonically with decreasing size, becoming significant for the smallest (0.35 mm diameter) size, allowing a limit to be identified for reliable model calibration.

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The Effect of Algorithm Form on Deformation and Instability in Tension

Cited by 5 publications

References 2 publications

Simulation of shear plugging through thin plates using the GRIM eulerian hydrocode

Simulation of shear plugging through thin plates using the GRIM eulerian hydrocode

Simulation of shear plugging through thin plates using the GRIM Eulerian hydrocode

Scale effects in necking

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