Mingtao Liu

• Research Director at Institute of Fluid Physics

Experiments referring to dynamic fracture of ductile metals, which is strongly dependent on the loading path, have been performed on the platform of an electromagnetically driven expanding ring. The time of the onset of fracture and the time at which the first complete fracture surface is formed were accurately measured by incorporating a B dot pro...

The expanding fracture of an explosively driven 1045 steel cylinder was studied. The fracture process and the expanding velocity of the cylinder were recorded by a high-speed camera and a Photonic Doppler Velocimetry (PDV) probe in real time. The fragments were recovered and analyzed by metallurgical examinations. The fracture mechanism, expanding...

We study the fracture behavior of a Cu plate under sliding detonation loading using wireexplosion technique. Both Doppler Pins Systems (DPS) and Scanning Electron Microscope(SEM) are employed in the experiments to study the velocity of the free surface and the microstructure of the recovered samples. A novel spalling phenomenon is substantially obs...

The self-organization of multiple shear bands in a 304L stainless steel(304LSS) thick-walled cylinder (TWC) was numerically studied. The microstructures of material lead to the non-uniform distribution of the local yield stress, which play a key role in the formation of spontaneous shear localization. We introduced a probability factor satisfied th...

The evolution of spontaneous shear bands in a 304L stainless steel (304LSS) cylinder subjected to external explosive loading was numerically studied. As an instability process, the initiation of a shear band is strongly dependent on the non-uniformities of the material. A probability factor satisfied the Gaussian distribution was introduced into th...

The numerical stability of the explicit precise algorithm, which was developed for the viscoplastic materials, was analyzed. It was found that this algorithm is not absolutely stable. A necessary but not sufficient condition for the numerical stability was deduced. It showed that the time step in numerical calculation should be less than a certain...

The collapse of a 304L stainless steel thick-walled cylinder (TWC) was numerically studied. A probability factor satisfied with Gauss distribution was introduced into the macroscopic constitutive relationship to provide perturbation in modeling. The initiation and propagation of multiple shear bands was successfully triggered by the probability fac...

The explosion induced fracture of metallic cylinder under different detonating modes was simulated. The results show that different detonating modes lead to significant differences on the pressure and apply work history of the cylindrical shell. A semi-decoupling numerical method was proposed to thin the mesh size of the metallic cylinder and to si...

The formation of an adiabatic shear band (ASB) experiences three stages: stable plastic flow, nucleation and a fluid-like stage. For different stages, the microstructures of the material undergo great changes. The mechanical behavior of the material in each stage has its own unique characteristics. To describe these characteristics, a multi-stage m...

The expanding fracture of cylindrical shell subjected to internal explosive detonation is investigated experimentally. The velocity history of the outer surface of cylinder is recorded by VISAR. High-speed camera is used to capture the failure process of the cylindrical shell. A part of the fragments are recovered softly by using a recycling bin fi...