Junpeng Liao

Effect of Geometry Change on the Deformation in C-Shaped Armatures Through 3-D Magnetic-Structural Coupling FE Analysis

An armature is a key component in a rail gun the geometry directly affects the performance of the armature during the launching process, which can be easily destroyed by enormous forces. In order to guarantee the success of the electromagnetic launch (EML), a high-strength armature is greatly needed. In this paper, we focus on the deformation in the C-shaped armature caused by electromagnetic forces. A 3-D magnetic-structural coupling finite-element method is carried out to analyze the effect of different geometries. Four geometrical parameters are used to characterize the maximum deformation of the armature. These are the armatures shoulder thickness, arm thickness, contact length, and inner curve radius. We get an effective conclusion for designing the high-mechanical-strength armature to improve the performance of the EML.

Multi-factor optimization of railgun using orthogonal test approach and field-circuit method

Today the energy storage systems are still encumbering, therefore it is useful to think about the optimization of a railgun system in order to achieve the best performance with the lowest energy input. In this paper, an optimal design method considering 6 parameters is proposed to improve the energy conversion efficiency of a simple railgun. In order to avoid costly trials, the field-circuit method is employed to analyze the operations of different structural railguns with different parameters respectively. And the orthogonal test approach is used to guide the simulation for choosing the better parameter combinations, as well reduce the calculation cost. The research shows that the proposed method gives a better result in the energy efficiency of the system.

Research of the resistance model in solid armature railgun

During the past few decades, various calculation models have been introduced into studying solid armature railgun. In this paper, four models, including constant resistance, speed resistance, current resistance, and multifactor resistance, were studied in detail. To verify their validity, experimental and simulation methods were adopted in both low- and high-velocity cases. By conducting a 3-D eddy current electromagnetic field simulation with the finite-element numerical method, the self-inductance gradient

Effect of geometry change on the deformation in C-shaped armatures through 3-D magnetic-structural coupling finite-element analysis

(L^{ \prime}_{r})

Nonlinear scaling study of a railgun

was got. The control equations of these different resistance models can be solved by the Runge–Kutta method. Comparisons of experimental and simulation results of these different resistance models indicated that an appropriate resistance model according to the experimental condition can improve the accuracy of simulation analysis. The friction coefficient resistance model can describe armature resistance during the movement process in both low- and high-velocity cases.

Effect of geometry change on solid C shaped armature

Armature is a key component in railgun, the geometry of which directly affects the performance during the launching process, and it can be easily destroyed by enormous forces. In order to guarantee the success of the electromagnetic Launching (EML), a high-strength armature is needed. In this paper, we focus on the deformation in C-Shaped armature caused by electromagnetic forces. A 3-D magnetic-structural coupling finite-element method has been carried out to analyze the effect of different geometries. Four geometrical parameters are used to characterize the maximum deformation of armature. These are the armature shoulders thickness, the armature arms thickness, the contact length and the inner curves radius. At last, we get some effective conclusion for designing the high mechanical strength armature to improve the performance of the EML.

Salvo Performance Analysis of Double-Projectile Railgun

Scaling method has been used widely in railgun technology. But nonlinear problem is seldom studied because of the complexity and uncertainty. In order to employ the scaling method better, the paper brings the nonlinear drag model to the solid armature railgun circuit. Several drag functions were compared including drag model associated with velocity (VDM), drag model associated with current (CDM), and drag force associated with integrated factors (IDM). Scaling relationships of these drag models were discussed. And then, a novel experiment was constructed to compare the drag models at low velocity. Further simulations at high velocity are also studied. At last, the nonlinear scaling method was verified by an example at high velocity. It shows that VDM is far from satisfactory at high velocity. The scaling conditions of VDM are too strict to use in practice. CDM is workable only in high velocity condition which satisfies conditions of linear scaling method (LSM) in nature. But it is worthless when the velocity is less than about 0.5 km/s. Although a bit complex, IDM is very accurate at any condition. Coefficient α in IDM should be taken considering different test conditions. Scaling relationships of IDM could not be derived at low velocity due to nonlinearity. While at high velocity, IDM could be simplified to CDM and realize LSM. Further research indicates that IDM could use the scaling method directly and realize approximate LSM at high velocity. Due to the work range of the solid armature is usually 1~2km/s, nonlinear scaling method could be used in a railgun with IDM. What should be noted is that the velocity scaling factor must be controlled above about one quarter to avoid the nonlinear field. A detailed analysis of the experiments and simulations will be presented in this paper.

Optimization Design of Multi-Parameters in Rail Launcher System

Armature takes an important role in the electromagnetic launch process. High current densities in the armature can result in high local temperature and consequent loss of strength and even melting and erosion. Conventional C-shaped armature is widely used which experiences high current densities in three areas: the leading edge, the trailing edge, and the throat. It is argued that if the armature shape is modified to better align with the magnetic field, the current density distribution could be more uniform. This paper tries to analyze the effect of the geometry change on C-shaped armature at low velocity. The geometry of the armature was changed to improve the current density and temperature distribution and reduce the erosion. Four variants of C-shaped armatures were designed to study the specific features, including a conventional C-shaped armature (CCA), a rounded leading edge C-shaped armature (LCA), a rounded trailing edge C-shaped armature (TCA), and a rounded incorporate edge C-shaped armature (ICA). A novel low-speed experiment was constructed and tested. The armatures were eroded and recovered to compare the improved effect. Then finite element simulations according to the experiments were taken to analyze the further results. It is proved that the curved edge of the armature could reduce the nonuniformity of current density and temperature distribution greatly. LCA and ICA showed less erosion on the contact surface due to the rounded leading edge. The trailing edge could improve the uniform of the current on the interface. ICA is the best choice of the four armatures which combines the effect of LCA and TCA. Erosion and transition mechanism were analyzed at last. A detailed description of the experiments and simulations will be presented in this paper.