Large strain deformation and fracture of quai-brittle materials with application to process comminution equipment

Loughran, J.G., and Anderson, S. (2004) Large strain deformation and fracture of quai-brittle materials with application to process comminution equipment. In: Proceedings of the 6th World Congress on Computational Mechanics. pp. 1-9. From: Sixth World Congress on Computational Mechanics, 5-10 September 2004, Beijing, China.

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This paper reports a finite element investigation of the impact of steel debris against sugar mill shredder hammer tips. During cane preparation, billets of cane are comminuted against tungsten carbide (WC) tips with impact velocities approaching one-third the speed of sound. Foreign debris (often hardened steel pins) in the input stream, result in a high probability of fracture to the WC tiles. The impact process when steel debris comes into contact with the WC is modelled using explicit finite element dynamics under plane strain conditions. Following traditional large strain finite element procedures the deformation gradient is split in a multiplicative sense into elastic and plastic components. Incremental procedures are required since the problem is invariably path dependent. This requires a numerical approximation to the constitutive law for update of local stress and other internal variables during each increment. The finite plastic evolution equations are discretised by an exponential map integrator while the elastic components are discretised by the standard backward-Euler scheme. Key issues addressed are: I) appropriate modelling of deformation mechanisms at an elemental level to enable prediction of deformation, strain, stress and contact laws; 2) inclusion of finite strain elasto-plasticity; 3) development of fracture criteria; 4)detection procedures for monitoring contact between deformable discrete elements (fragments) and continuum regions; 5) representation of interaction laws for contacting elements. A Rankine rotating crack model is used to characterize the WC and the projectile is modelled as elasto-plastic. The evolution of racking which occurs due to impact is studied. The effect of the WC geometry on resistance to crack initiation is also noted and explored numerically. Agreement with experiment is excellent.

Item ID: 14779
Item Type: Conference Item (Research - E1)
ISBN: 7-89494-512-9
Keywords: brittle; comminution; constitutive; damage; fear; strain
Date Deposited: 31 Aug 2017 23:22
FoR Codes: 09 ENGINEERING > 0915 Interdisciplinary Engineering > 091599 Interdisciplinary Engineering not elsewhere classified @ 40%
09 ENGINEERING > 0912 Materials Engineering > 091202 Composite and Hybrid Materials @ 40%
09 ENGINEERING > 0903 Biomedical Engineering > 090301 Biomaterials @ 20%
SEO Codes: 87 CONSTRUCTION > 8703 Construction Materials Performance and Processes > 870302 Metals (e.g. Composites, Coatings, Bonding) @ 50%
86 MANUFACTURING > 8613 Transport Equipment > 861301 Aerospace Equipment @ 30%
87 CONSTRUCTION > 8799 Other Construction > 879999 Construction not elsewhere classified @ 20%
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