| The mass-spring-damper devices are widely used in the mechanical equipments. When subjected to the coupling effect of complex excitations (such as working load, environment excitation, disturbance from the ground, etc.) or excitation frequency shift, the performance of the damping devices is obviously deterioration. This paper is based on the fact that the biological body in nature can adapt to the strength of the external load, the change of frequency to adjust its structure to realize efficient damping. Taking the woodpeckers’ head and horses’ limbs as biological prototypes, the nonlinear characteristics of biological tissues, damping mechanism, design of bionic damping device and the optimization design method were systematically studied in order to provide theoretical and technical support for the design and application of bionic damping device in engineering practice.The synergetic damping mechanisms of the biological tissues in the woodpeckers’ head and horses’limbs are clarified respectively. The high-efficiency vibration damping mechanism in the woodpeckers’head is due to the synergistic effects of the beak’s nonlinear elastic force, muscles’nonlinear elastic and damping force and cerebrospinal fluid’s hydraulic resistance. And the synergetic effect of skeleton, muscle and paw in the horses’ limbs when suffered by the environmental excitation was illuminated. Then the nonlinear dynamic modelling of woodpeckers’ head and horses’ limbs were developed respectively considering the influencing factors of nonlinear stiffness of the beak, nonlinear stiffness and damping of muscle and soft tissue, the fluid resistance of cerebrospinal fluid and nonlinear muscle force of horses’ limbs. The synergism nonlinear dynamic vibration reduction models were established based on woodpeckers’ head and horses’ limbs. The stiffness and damping variation rules of beak, muscle and cerebrospinal fluid in the woodpeckers’ head and skeleton, muscle and paw in the horses’limbs were discussed. Based on the incremental harmonic balance theory, the dynamic model of woodpeckers’ head was calculated in the vicinity of the fundamental harmonic vibration.The variable stiffness and damping system experiment platform was built and the experimental bench body, mass element, nonlinearity element, nonlinear damping elements, vibration measurement and signal acquisition and analysis system were designed, selected and erected. Thus the system stiffness, damping controllable, adjustable and real-time measurement of vibration signal was realized. The system dynamic characteristics of the proposed woodpecker head model which has the effect of cubic stiffness and square damping was experimentally studied, including system frequency response characteristic experiments and damping performance experiment etc. The results showed that the designed platform has a narrow resonance zone, the variation amplitude decreases rapidly when the excitation frequency far away from the resonance area. So it ensures the system has a good damping effect in a wide frequency domain and vibration frequency range transmission rate can be limited within10%, and achieved good damping effect. The effectiveness of the woodpecker head vibration system dynamics model, numerical analysis conclusion and cubic stiffness and square damping element synergistic damping effect was also verified.Based on the biological prototype of the woodpeckers’ head and horses’ limbs and using nonlinear materials or devices such as viscoelastic damping, magnetorheological, air spring etc., a method of bionic design engineering vibration damping device called unit module combination bionics damping function was established. Meanwhile, a new type of variable stiffness and damping of bionic damping unit was constructed and the relationships between all of the bionic damping element stiffness, damping and the structure parameters, external incentives were derived, each unit design principles were given and the air spring damper unit with bionic and viscoelastic damping vibration unit was taken as an example to study the effect of the main structural parameters on unit nonlinear stiffness and damping.Aiming at the increasing complexity of mechanical equipment dynamic environment, taking the typical machining equipment, JA31-160C type closed single point press equipment which has a typical feature of large bearing capacity, bearing variety of coupling motivation (load motivation, environment and basic interference etv) effects, for example, bionic vibration reduction functional unit module combination design method was used to study the effectiveness of the designed base. In addition, according to the sensitivity analysis and structure dynamic modification theory, taking the minimum vibration transfer rate under the load excitation, environment excitation coupling excitation etc and inherent frequency far away from the resonance frequency as the double objective function, the allowable vibration and the non-resonance as constraint conditions, the damping device structure parameters as optimization variables, put forward a dynamic optimization method of bionic damping device which suitable for multi target and can consider the coupling excitation effect of the load excitation and environment excitation.This paper was funded by the Ministry of education specialized research fund for the doctoral program (20110131110043) and the development plan project of Shandong province science and technology (2011GGX10328). |
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