The paper presents results obtained by experimental and numerical research focusing on the influence of the strikers’ geometry at the images of the destruction created in hybrid composite panels after applying impact load. In the research, the authors used four strikers with different geometry. The geometries were designed to keep the same weight for each of them. The composite panels used in the experiment were reinforced with aramid and carbon fabrics. An epoxy resin was used as a matrix. The experiments were carried with an impact kinetic energy of 23.5 J. The performed microscopy tests allowed for determination of destruction mechanisms of the panels depending on the geometry of the striker. The numerical calculations were performed using the finite element method. Each reinforcement layer of the composite was modeled as a different part. The bonded connection between the reinforcement layers was modeled using bilateral constraints. That approach enabled engineers to observe the delamination process during the impact. The results obtained from experimental and numerical investigations were compared. The authors present the impact of the striker geometry on damage formed in a composite panel. Formed damage was discussed. On the basis of the results from numerical research, energy absorption of the composite during impact depending on the striker geometry was discussed. It was noted that the size of the delamination area depends on the striker geometry. It was also noted that the diameter of the delamination area is related to the amount of damage in the reinforcing layers.
Purpose -The purpose of this paper is to present a new concept of a multi-module electromagnetic launcher with pneumatic assist. The authors focus on the problem of modelling a two-module electromagnetic launcher consisting of a coil-gun (module C) and a rail-gun (module R), as well as on the key problem of determining their position-dependent parameters, i.e. the resistances and inductances of discharging electrical circuits connected with the both modules. Special attention is paid to the possibility of influencing the missile's flight via basic controller variation of the initial voltage values across the terminals of the capacitor batteries supplying current to both modules C and R. Design/methodology/approach -Analysis of the electromagnetic launcher has been based on the circuit-field approach. Differential equations describing movement of the missile have been drawn from circuit theory. The Finite Element Method and the Comsol Multiphysic program were used to determine position-dependent parameters in module C. It is worth emphasising that the effect of saturation (resulting from B-H curve for ferromagnetic part of the considered magnetic circuit) was taken into account. The influence of the initial missile speed adjusted in a pneumatic assist unit on the missile's velocity was also considered and illustrated by appropriate simulations (the Matlab program). Findings -In analysing the flight of a missile along coil-gun and rail-gun modules, it is necessary to distinguish between three specific stages of the moveable element: the "fall in" stage, the "drive through" stage and the "fall out" stage. One of the most important findings is that during modelling, it is necessary to take into account of all the three above-mentioned stages of missile movement and, in particular, the "fall in" stage. It was shown both by computer simulations and laboratory investigations that this stage plays an important role in determining the time curves of decaying currents in discharging electrical circuits of both module C and module R.Research limitations/implications -The main difficulties are related to determining the influence of air drag force upon missile movement (especially in module C), as well as identifying an accurate value for contact resistances and friction force between the rails and the missile in module R. Practical implications -Hybrid construction employing propelling units of different characters should be treated as a promising and challenging trend in developing launcher structure. One of the most significant advantages of such a solution is the possibility of influencing missile velocity during its flight. Social implications -Since the first device was successfully completed in 1920 the continuous rise in the interest on electromagnetic launchers has been observed. As far as their social and technical impact is concerned, one of the most promising fields of interest seem to be launchers of satellites, high-pressure compressors, simulators modelling collisions between meteoroids and the surface of the ...
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