Papers by Author: Lei He

Abstract: The deep understanding of human-rifle interaction is not only crucial to improve the rifle firing accuracy, but also important for rifle design. In this paper, the construction of a biological coupling human-rifle model for standing posture was created using MSC.ADAMS and BRG.LifeMOD. Firstly, the rifle model was built by virtual prototyping technology based on the software of MSC.ADAMS. Secondly, the human model was generated in BRG.LifeMOD on the database of Human dimensions of Chinese adults. Finally, the simulation of human-rifle system was performed by the model, in which the interface between the human model and the rifle model was modeled using corresponding constraints. The feasibility of the application of biology mechanics model of three-dimensional digital human body to the researches of human-rifle system was explored, and it can provide the basis for the researches of human-rifle interaction and dynamic response of human-rifle system.

Abstract: An experiment gun mount system is used to clamp the small arms and replace gunner to conduct the automatic shooting in the shooting accuracy test. Because of the concomitant phenomena such as high shock and vibration when shooting, to study the vibration characteristics of the system, a modal analysis method was proposed and the experimental points, including the exciting points and the vibration pickup points, were determined on the basis of its geometric model. Based on the Fast Fourier Transform technique, the CRAS modal testing system was built. The modal experiment of the system was carried out by hammer blow method. The exciting signals, spectra of impacting prompt power, vibration acceleration and their frequency response functions were obtained. The first six order vibration modes, damping ratio and the corresponding vibration frequencies were obtained, which laid the foundation for dynamic response calculation and further optimization design of the system in the future.

Abstract: The automatic weapons suffered the coupling load of in-bore pressure and temperature load during firing, which exerted a serious influence on the gun barrel life. Suppose the gun barrel was thick wall cylinders, the relations among the radial stress, tangential stress, longitudinal stress and equivalent stress in thick wall cylinders enduring interior pressure and temperature loads were analyzed by traditional analytic method, 2D finite element method (FEM) and 3D FEM respectively. Boundary effects of the stress field in thick wall cylinders were also analyzed. The obtained results showed that 3D FEM is suitable for the analysis on boundary effects, and the coupling stress could be designed and optimized by adjusting the interior pressure or temperature loads.

Abstract: To investigate the wounding effects in human on the basis of the similarity theory, by taking the temporary cavity as the research object, through the analysis on the forming of cavity and its physical process, main influencing factors effecting temporary cavity are obtained, which can provide a good theoretical basis for similarity research in wounding ballistics in the future, and the killing effect of the high speed steel ball is more deeply described.

Abstract: To research the strength of composite material barrels, based on the CDM theory, an energy-based stiffness degradation method is proposed to predict the progressive failure properties of steel- fiberglass/ epoxy composite laminated barrels. Three failure modes of fiberglass/ epoxy composites, including fiber breakage, matrix cracking and fiber/matrix interface shear failure are considered in the present model. A 3D finite element technique including the multiframe restart analysis is employed to conduct the progressive failure analysis. The results indicate that the mode considering the stiffness degradation and progressive failure of the material is more reasonable on researching the strength of composite material barrels. The strength of composite material barrels in this paper is influenced by the fiber strength mainly.