Preparation Of Film-substrate Wrinkling System For Elastic Wave Band Gaps Control

Phononic crystals can be used to suppress the propagation of elastic waves,and have wide applications in elastic waveguides,vibration control,acoustic stealth.Theoretical studies have found that the periodic patterns generated by elastic destabilization have the characteristics of phononic crystals,which can control the propagation of elastic waves in film-substrate systems.However,the experimental realization of periodic patterns prepared by elastic instability remains a challenge,due to the stress mismatch which may leads to interfacial debonding and structural warping.Therefore,it is of great significance to carry out researches on the preperation and the band gap characteristics of the film-substrate wrinkling system for expanding its application in the field of vibration and noise reduction.Based on the above background,the following researches on the plane film-substrate wrinkling system are carried out.(1)A novel experiment method was proposed to prepare film-substrate wrinkling systems without the detachment and the warpage,in which film and substrate are selected homologues.Two-phase moisture curing process is adopted to control the physical state of the substrate,the surface pattern and the residual stress.A finite element model was established for instability analysis,the influence of different parameters on the wrinkling pattern was analyzed,the relationship between compressive strain,thickness ratio,modulus ratio and the wrinkle wavelength amplitude were explored.(2)Based on Bloch wave theory and finite element method,an automatic program of energy band structure is made,which can be used for calculating the band gap characteristics of film-substrate wrinkling system.Based on the combination of dimensional analysis method and finite element simulation,the influence of key parameters on the band gap characteristics was studied.The relationship between the deformation,geometric dimensions,material parameters and the band gap characteristics of the film-substrate wrinkling system was discussed.Design guidelines are given based on actual engineering requirements,which provide guidance for the determination of film thickness and elastic modulus.Vibration experiments of wrinkled samples were carried out,which matched well with the numerical simulations.(3)A finite element model was established by combining film-substrate wrinkling systems with different bandgap characteristics.Some typical combined film-substrate systems with different parameters were selected to study their bandgap characteristics.Numerical results show that the combined system has a wider band gap,meanwhile the band gap of the combined system will move down when the pattern defects occur.