| As a highly efficient blade vibration damper,the dry friction flange damping block is widely used in aeroengine turbine blade damping systems.Because of its advantages such as simple structure,light weight,good vibration reduction effect,high reliability,and strong environment adaptability,many scholars at home and abroad have studied it in recent years.The research mainly focuses on the improvement of the dry friction damping model,the improvement of model calculation methods,and has achieved some scientific research results.In this paper,the friction contact characteristics,coupling damping characteristics and response characteristics of the dry flange friction damping block are studied in three aspects.Firstly,starting from the contact characteristics of the flange damping block and the blade,a geometric model describing the frictional contact between the dry friction damping block and the turbine blade is established.According to the geometric model of blade contact with the damping block,a flat plate friction contact model with a rounded flat punch was established.Based on this model,the distribution law of normal force,tangential force and tangential displacement of the contact surface under different geometric parameters were studied.The influence of geometric parameters on hysteresis curve,contact stiffness and energy dissipation was further studied.The results show that with the increase of the contact area ratio,the friction contact model is gradually transformed from the cylindrical surface line contact into the ideal plate contact,the area enclosed by the hysteresis curve is reduced,and the energy consumption is reduced during each vibration friction cycle,when the contact is a cylindrical surface There is a maximum value for the energy consumption of the damping block at line contact.Secondly,based on the frictional contact characteristics of the turbine edge plate damping block and the non-linearity of the dry friction damping damping problem,and considering the coupled vibration when the damping block and the blade friction are damped,the assumption conditions for the two-dimensional local-global unified slip model Next,combining MATLAB's advantages in solving nonlinear problems,the influence laws of positive and negative excitation forces on the equivalent contact stiffness and equivalent damping of the damping system are studied and analyzed,and the tangential and longitudinal directions of the damping block to the blade are studied respectively.The damping effect was compared and judged.The results showthat under the excitation force of the turbine blade,the non-linear damping of the contact surface presents the characteristics of stiffness softening of the blade.Each excitation force corresponds to a best positive pressure to minimize the amplitude of the blade,and the damping block cuts the blade.Vibration damping effect is significantly better than axial.Finally,on the basis of the contact characteristics and coupling damping characteristics of the damper block with the blade,based on the hypothesis of the two-dimensional local-global uniform slip model where the damper block contacts the blade,the ANSYS simulation software is used in combination with the turbine of the friction damper block with flange plate.The response characteristics of the leaves were studied.The influences of positive pressure at the contact surface,excitation force,contact stiffness and friction coefficient on the peak response and frequency of the blade were studied.The results show that the dry friction damping block not only plays the role of friction energy dissipation and vibration reduction when the blade is vibrating,but also can frequency-modulate the blade under certain conditions.When designing the dry friction damper,not only should the damping block work as much as possible Under the optimal positive pressure,the vibration suppression caused by the damping effect of the damping block on the blade should also be considered. |
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