No abstract

In this paper, a method for the introduction of the effect of vib-, :ration frequency on dynamic contact stiffness of joints is presented. The 'method is based on the measurement of the natural modes of vibration of a simple mechanical system containing the joint to be investigated. The results s of measurement are used, through a sensitivity technique, for the identification of a joint stiffness matrix. This matrix is assumed, at firs, to be invariant, i.e, independent on the mode of vibration. However, the utilization of the identified eigensolution and the equations of sensitivity .corresponding to a single mode of vibration, enable one to obtain, for this: mode, a correction joint stiffness matrix. The validity of the method has been tested by numerical simulation on a case of a plane prestressed joint between two beams.

This work is concerned with the study and use of dry friction dampers for : :vibration control. First, the characteristics of the friction damper are 'determined. Then, the friction damper is applied to a hinged-hinged bean, The amplitude-frequency response for a harmonic excitation is determined both theoretically and experimentally. For linearization of the equations. bf motion, the friction force is replaced by an equivalent linear viscous : force dissipating the same energy per cycle. The results obtained from experiments and theory are in good agreement, and it is shown that, by a suitable choice of the ratio of the friction force to applied force' the * friction damper can be an effective damping device.

The study of barrel vibration is important for the performance of firing; Weapons .In this paper the finite element method is used for modelling the • barrel and-determining its characteristics .A complete analysis of the course of affecting forces on liarrel during the whole period of action is carried out for defining them.rIte calculation procedure is programed for. easy analysis of barrel response. The influence of barrel vibration on successive uency analysis of the recorded details is carried out.The comparison between muzzle trajectory at different modes of fire. A real time analysis and a freq-'frequency analysis of the recorded d tail:carried out.The comparison. between both theoretical and experimental results proved the accuracy of the proposed model l-INTRODUCTII M The barrel is the most impo r ,nt weapon component ,it.gives the projectile required velocity direction any; t.abilization .Most available references discuss the barrel design as a thick-walled cylinder stressed by the internal pressure of powder gases n ,4ecting the effect of vibration on barrel design. On the other hand, bary.F1 vibrations largely affect the hitting accuracy of a weapon. The problem of barrel vibra,i has been discussed in its general case * MTC i M.Sc Chair of Weapons an Ammunition .