Analysis And Design Of Snap-through Characteristic Of Compliant Bistable Cosine-shaped Beam

The unique characteristics of bistable structures such as variable stiffness,snap-through,and steady state maintenance make it of great importantance in sensors,actuators,vibration isolation and energy harvesting devices.In order to solve the problem of strong nonlinear mechanical behavior in kinematics and dynamics for a pre-curved bistable cosine-shaped beam,an analyzing model for the snap-through behavior is established based on the large deformation finite element method.The whole snapping-through process is numerically simulated to obtain the key factors affecting the bistable mechanical behavior.A new method for controlling the snap-through is proposed by using the pre-stress applied on the pre-shaped bistable beam.Then,a model was established to simulate the vibration response of a beam subjected to periodic excitation,and the influencing factors on bifurcation are obtained.Based on the static and dynamic characteristics of bistabe structures,a novel bandgap adjustable array structure for vibration attenuation is designed according to the local resonance theory.All these works provide a theoretical support for bistable devices and damping structures,which are presented as follows.(1)The snap-through analysis model for bistable cosine-shaped beams was established based on the large deformation finite element method.By using the multistep displacement loading method,the possible buckling modes and their transforming procedure are numerically obtained,which interprets reasonably the discontinuity of the force curve.Furthermore,The influence of structural parameters and loading methods of arc beam on discontinuity points(tips)of bi-stable jumps is studied systematically.And structural quality factor is introduced to judge the occurrence of the sharp point.A demarcation graph is obtained to produce sharp point or not.The bistability design method for achieving stable bistable mechanics with single snapping pathway is proposed,thus providing a theoretical basis to design and control the bistable snapping characteristics of compliant structures.The method of changing the pre-stress of bistable beam to control snap-through characteristic is proposed.The snap-through characteristics of the structure have been changed and stability has been improved by applying pre-stress.Snap-through threshold force and stroke are also adjusted.The experiment verifies the effectiveness of control method of snap-through,and provides technical support for expanding the adaptability of the bistable structure in complex working conditions.(2)The nonlinear dynamic bifurcation characteristics of a pre-curved bistable cosine-shaped beam subjected to harmonic excitation was analyzed.The nonlinear vibration analysis model of bistable beam is established.The effects of excitation amplitude,excitation frequency,and structural parameters on dynamic bifurcation characteristics were studied.A method for controlling the vibration of a bistable cosine beam is proposed.By changing the pre-stress of beam,the frequency of dynamic bifurcation is changed,which can effectively adjust bifurcation band of the structure.(3)Based on bistable cosine beam structure with specific snap-through characteristics,a vibration reduction array structure with adjustable frequency band is designed.Vibration reduction bandwidth is adjusted by switching two steady states.The mechanism of vibration reduction and effects of structural parameters on the characteristics of adjustable vibration reduction bandwidth is systematically studied.