Design And Band Gaps Of One-dimensional Quasi-zero-stiffness Memamaterial

With the developing of technology,circumstances and facilities have proposed more and more strict requirements for mechanical vibration controlling.Metamaterial,a new architected material with the fantastic ability to manipulate the elastic waves,has excellent applications for the vibration attenuation and noise reduction.In order to solve the hard issues,which is hard to design metamaterials for opening low-frequency band gaps and manipulating band gaps,this paper presents a tunable quasi-zero-stiffness(QZS)metamaterial.In here,the mechanism and manipulation method for band gaps is analyzed by theoretical calculation,numerical simulation and experimental verification.The main results of analysis are as follows.1.A new type of QZS compliant unit cell is designed by distributed shape optimization and based on the concept of curved-beam constant force compliant mechanisms.Generalized shooting method and finite element simulation are used for the statics analysis of this structure,the constitutive relation between reaction force and deformation can be obtained,and then the stiffness character of the unit cell can be also obtained by fitting and derivating.All results denote the designed structure has a good character of QZS and it can deform orderly.2.A one-dimensional QZS metamaterial is designed by arraying the unit cell in parallel.The simplified lumped mass-spring dynamic system is modeled by concentrated mass method;and the band gaps of the metamaterial under various of compression are realized by linearized stiffness and Bloch theory.Moreover,considering the size of structures is finite,the wave propagation in the finite periodic QZS metamaterial is analyzed by numerical analysis and finite element simulation,and then the mechanism of production for low-frequency band gaps is revealed.Finally,lumped mass-spring model and numerical analysis are used to study the effect of various parameters(the damping and numbers of unit cells)for wave attenuation property.3.The test specimens of the unit cell and finite periodic QZS metamaterials are manufactured by additive manufacture method.The constitutive relation between reaction force and deformation is realized by spring testing machine,the measured stiffness is obtained,and the QZS character of the unit cell is verified by experiment.By building shock test platforms,which use the shaker to apply vibration excitation and the acceleration sensor to collect in/out signal,and the transmissibility curves for deformed configurations are obtained.The low-frequency band gap character and the ability for tuning band gaps of one-dimensional QZS metamaterial are also verified by experiments.