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Modal Analysis of Medium Calibre Barrels

Lisy Peter, Bridik Lukáš

Problemy Mechatroniki : uzbrojenie, lotnictwo, inżynieria bezpieczeństwa

2019

Vol. 10, Nr 2 (36)

9--22

The paper deals with modal analysis of the two different medium calibre barrel weapons. At present time PC software which are based on FEM modal analysis enable not only create a new design but also check old design how be up to standard on the fire accuracy. Also at this time is big boom to make new armour personal carriers which are equipped with the medium weapon calibre systems. Many of them use standard design of bedding the barrel to the weapon case, however also they are created in new weapon design. The modal analysis is powerful method to describe their vibration properties which have the cardinal influence on the accuracy of fire. The barrels were modelled as 3-D objects with next configuration with aim to obtain right results and their mutual comparison. Figure 1-3 show design of the solved barrels. Modal analysis was performed by LS-DYNA software using iterative Lanczos method. In Tables 1-5, the natural frequencies for these barrels and their modifications and their corresponding own shapes are listed. Next Figures 4, 7-10, 12 show the courses natural frequencies versus modes. In Figure 11 are shown the modal shapes of the modified cylindrical weapon barrel with the armature.

An Experimental Approach to Vibro-Acoustic Study of Beam-Type Structures

Torres-Romero J., Cardenas W., Carbajo J., Segovia Eulogio E. G., Ramis-Soriano J.

Archives of Acoustics

2018

Vol. 43, No. 2

283--295

In this paper an alternative procedure to vibro-acoustics study of beam-type structures is presented. With this procedure, it is possible to determine the resonant modes, the bending wave propagation velocity through the study of the radiated acoustic field and their temporal evolution in the frequency range selected. As regards the purely experimental aspect, it is worth noting that the exciter device is an actuator similar to is the one employed in distributed modes loudspeakers; the test signal used is a pseudo random sequence, in particular, an MLS (Maximum Length Sequence), facilitates post processing. The study case was applied to two beam-type structures made of a sandstone material called Bateig. The experimental results of the modal response and the bending propagation velocity are compared with well-established analytical solution: Euler-Bernoulli and Timoshenko models, and numerical models: Finite Element Method – FEM, showing a good agreement.