| Sound quality is an important indicator which is widely used to evaluate the excellent performance of vibration and noise of the electromechanical system in the fields of aviation,aerospace,ship and vehicle.It composes of loudness,sharpness and roughness.Compared with the traditional sound level evaluation indicators,the sound quality comprehensively considers the sound level,the frequency characteristic and the physiological and psychological feelings of the human body.Therefore,compared with the customary noise control,the sound quality design is quite difficult.Structural vibration mode design is the basis of sound quality design.Composite plate structure is commonly used in engineering due to its light weight and high strength.However,the vibration and noise of the composite plate structure are large and there are multi-order modes.Modal resonance produces sound radiation and then causes sound quality(including loudness,sharpness,roughness,etc.)problems,which directly affects people’s subjective feelings and physical and mental health.Facing the multiobjective and multi-parameter problems in an objective evaluation of sound quality of composite plates and the thorny problem in structural mode frequency adjustment design,shape memory alloy(SMA)is introduced into composite plates in this paper.Combining with the idea of material gradient design,the dynamic modeling theory,modal characteristics and global sensitivity analysis method of sound quality of SMA gradient composite plate are systematically studied,aiming at achieving sound quality design of SMA gradient composite plate from the point of view of material design.The research in this paper will provide new theory and method for the sound quality design of SMA composite plate,which has important theoretical and practical significance.A homogenization method for inhomogeneous SMA reinforced composites considering interfacial phase is proposed to solve the problem of interfacial stress transfer in inhomogeneous composites with pre-strained SMA and to take into account the periodic distribution of SMA reinforced materials in the matrix.A three-phase cylindrical stress transfer model with embedded pre-strained SMA fiber wire was constructed,and the mathematical expressions of axial stress and shear stress of SMA fiber,interfacial phase and matrix in SMA composites were derived.Based on homogenization equivalent method and stress expression,the macroscopic effective modulus of SMA composites was obtained.Stress characteristics of SMA fibers and interfacial phases in SMA composites are analyzed,and the correctness of the theoretical method is verified by experiments,which provide modulus parameters for dynamic modeling of SMA composite plates.For the demand of adjustable mode frequency in sound quality design and the inadequacy of traditional composite plate in adjusting mode frequency from the structural point of view.From the point of view of material design,the idea of improving dynamic characteristics of SMA composite laminates is presented.Considering thermal effect and SMA pre-strain recovery force,a dynamic modeling method of SMA composite laminates considering in-plane forces is proposed.The gradient distribution mathematical model of SMA volume fraction of SMA composite laminates under the condition of constant SMA total integral number was established.Based on Hamilton’s variational principle,a dynamic model of SMA composite laminates was established considering the combined effects of SMA pre-strained characteristics,temperature thermal expansion and gradient distribution.Vibration control equation and the frequency equation of SMA orthogonal symmetric gradient composite laminate and SMA oblique antisymmetric double gradient composite laminate are derived.The modal properties of SMA gradient composite laminates in thermal environment are analyzed,and the effects of different gradient distribution,pre-strain,material volume fraction and structural size parameters on the vibration modal characteristics are revealed.Aiming at the interfacial continuity and modeling accuracy caused by the difference of modulus between surface layer and a core layer of light SMA composite sandwich plate,a dynamic modeling method of composite sandwich plate based on Reddy high-order shear and mixed variable theory was proposed.A dynamic model of SMA composite sandwich plate based on Reddy high-order shear theory and a dynamic stratification analysis model of SMA composite sandwich plate based on Reddy high-order shear-mixing variable theory were established for the composite sandwich plate consisting of surface-embedded SMA filament and graphite gradient core layer.The effects of gradient distribution of graphite in the core layer,volume fraction of SMA in the surface layer and SMA pre-strained on the mode characteristics of SMA composite sandwich plate were analyzed.To solve the difficult problem of how to effectively determine the quintessential sensitive parameters in the sound quality design of SMA composite plate,a global sensitivity analysis method for SMA composite plate is proposed.A vibration and sound radiation model of SMA composite plate based on spatial discrete-mode decoupling is established and implemented at sound quality models such as loudness,sharpness and roughness.The effects of pre-strain,volume fraction and gradient distribution of SMA fibers on sound radiation and sound quality of SMA composite plates are analyzed.The correlation relationship between multi-objective and multi-parameter in the sound quality design of SMA composite plates was established,and global sensitivity analysis of SMA composite plates was carried out based on the Morris method.In checking to see the dynamic modeling theory and method of SMA composite plate proposed in this paper,an experimental study on vibration and sound of SMA composite plate was performed.Experimental samples of SMA orthogonal gradient composite laminate,SMA oblique gradient composite laminate and SMA composite sandwich plate were designed and made.Modal test,sound radiation and sound quality test of SMA composite plate and corresponding theoretical calculation are carried out.The theoretical predictions are well matched with the experimental results,which verify the correctness and validity of the theoretical methods in this paper. |
PDF Full Text Request