Ren Huilan

A comparative investigation on motion model of spherical fragments penetration into gelatin

Gelatin is a popular tissue simulant in biomedical applications. The behavior of a spherical fragment and the effects of penetrating a simulant are similar in biological tissue. In order to accurately describe the interaction between a spherical fragment and muscle tissue, this paper discusses the wounding mechanism and the difference between the Sturdivan model, the Segletes model, the Liu model, and an improved motion model previously established considering the effect of strain rate by us based on the properties of gelatin. In addition, experiments conducted into spherical fragment penetration into gelatin, with fragment diameters 3, 4 and 4.8 mm, and acquisition of the corresponding motion law are discussed. Numerical calculations reveal that the motion model has a better fit with experimental values than the Sturdivan, Segletes and Liu models. Further, it more accurately describes the motion of a spherical fragment penetrating gelatin than other models and also has good generality. Thus, it can provide a theoretical reference for small arms ammunition design and wound treatment.

Numerical study on the fracture characteristicsof projectile material under impact loading

As one of the most common material used for projectile, the numerical simulation about high strength steel about its fracture characteristics under impact loading has always been emphasized. These kinds of problem often involved in the non-linear dynamic response and fracture of multi-material at high temperatures and pressures and strain rate. We put forwards a kind of mapping algorithm about local marked particles through coupling Lagrangian particles and Eulerian meshes. It is obtained by adding marked particles with regular hexahedral influence domain. According to the topological relation between particles and cells, the physical variables of cell are mapped to particles by weighted influence domain. Based on MPI standards, 3D parallel multi-material program with particles was developed. Besides, Johnson-Cook constitutive equation and fracture criterion about effective strain. A series of penetration in different working conditions were simulated and compared with experiment. It is found that the algorithm, which combines the best feature of Eulerian method and Lagrangian method, could be applied in simulating large deformation and fracture process of metal material. At the same time, the computational efficiency and accuracy could also be guaranteed. It is concluded that the improvement could make the algorithm more suitable for the simulation of various impact dynamic problems.

NUMERICAL SIMULATION OF DYNAMIC FAILURE FOR ALUMINA CERAMIC

The plate impact experiments have been conducted to investigate the dynamic behavior of alumina. Based on the experimental observations, the three-dimensional finite element models of flyer and alumina target are established by adopting ANSYS/LS-DYNA, several cases were performed to investigate the fracture behavior of alumina target under impact loading. By analyzing the fracture mechanism and damage process of the alumina target, it is concluded that the nucleation and growth of great number of radial and axial cracks and circumferential cracks play a dominant role in the fracture behavior of alumina target. The stress histories of alumina target are simulated. By the comparison of experimental results with the numerical predictions, a good correlation is obtained.