轻质隔声夹层板结构声振耦合拓扑优化

为了满足夹层板结构轻质及隔声性能优化需求,提出了一种基于线性材料插值模型的三场浮动投影动力学拓扑优化方法,进行夹层板结构声振耦合拓扑优化设计。首先,结合混合位移/声压(u/p)有限元格式和线性材料插值模型,解决多场耦合界面依赖性问题和低密度区域局部模态问题;其次,面向三维轻质夹层板结构声振耦合特性,建立以隔声性能最大化为目标,轻量化体积分数为约束的优化范式;第三,依托阻抗管隔声性能试验场景,对三维夹层板结构有限元数值模型进行拓扑优化设计,并结合阻抗管试验验证方法的准确性和有效性;最后,将所得优化构型与常见夹层板构型的隔声性能进行对比。研究结果表明:采用所提方法可获得性能优越的新颖拓扑构型,1100~1300 Hz优化目标频段对应的优化目标隔声性能即传声损失总值从197.62 dB提升到205.09 dB,且数值仿真结果与试验结果吻合良好。在结构同等质量下,优化目标频段拓扑构型的隔声量性能优于常见开孔/闭孔矩形蜂窝状、蜘蛛网状夹层板结构的隔声量性能。

考虑声振耦合的平板结构声振特性优化研究

研究多个动力吸振器优化结构的声振特性。根据Hamilton变分原理建立多个动力吸振器—平板—介质系统的声振耦合动力学方程,给出简支边界条件下耦合方程的解;以吸振器的质量、刚度、阻尼和位置为设计变量,以平板结构表面平均振速级和辐射声功率级为优化目标,采用遗传算法进行优化研究。研究表明:在一定频段内,单个动力吸振器能够降低优化目标10 d B左右,采用多个动力吸振器能够控制结构较宽频带的噪声;对于水下结构,可采用两个动力吸振器进行优化,但不能将空气中吸振器的优化结果直接用于水下结构。研究结果可为动力吸振器的减振降噪设计提供理论依据。

Application and optimization design of non-obstructive particle damping-phononic crystal vibration isolator in viaduct structure-borne noise reduction

The problems associated with vibrations of viaducts and low-frequency structural noise radiation caused by train excitation continue to increase in importance.A new floating-slab track vibration isolator-non-obstructive particle damping-phononic crystal vibration isolator is proposed herein,which uses the particle damping vibration absorption technology and bandgap vibration control theory.The vibration reduction performance of the NOPD-PCVI was analyzed from the perspective of vibration control.The paper explores the structure-borne noise reduction performance of the NOPD-PCVIs installed on different bridge structures under varying service conditions encountered in practical engineering applications.The load transferred to the bridge is obtained from a coupled train-FST-bridge analytical model considering the different structural parameters of bridges.The vibration responses are obtained using the finite element method,while the structural noise radiation is simulated using the frequency-domain boundary element method.Using the particle swarm optimization algorithm,the parameters of the NOPD-PCVI are optimized so that its frequency bandgap matches the dominant bridge structural noise frequency range.The noise reduction performance of the NOPD-PCVIs is compared to the steel-spring isolation under different service conditions.

Optimization of Vibration and Noise Performance of Permanent Magnet Synchronous Motor for Electric Vehicles

In the design of the motor used for electric vehicles(EVS),vibration and noise problems are often ignored,which reduce the reliability and service life of the motor.In this paper,an interior permanent magnet synchronous motor(IPMSM)with high power density is taken as an example,and its electromagnetic vibration and noise problem is investigated and optimized.Firstly,the factors that generate the electromagnetic force harmonic of IPMSM are analyzed by theoretical derivation.Furthermore,the mode and electromagnetic harmonic distribution of the motor are calculated and analyzed by establishing the electromagnetic-structure-sound coupling simulation model.Then,by combining finite element method(FEM)with modern optimization algorithm,an electromagnetic vibration and noise performance optimization method is proposed in the electromagnetic design stage of the motor.Finally,an IPMSM is optimized by this method for electromagnetic vibration and noise performance.The results of comparison between before and after optimization prove the feasibility of the method.

Structural topology optimization on sound radiation at resonance frequencies in thermal environments

Thermal and acoustic environments pose severe challenges to find optimal design that exhibits ideal acoustic characteristics the structural design of hypersonic vehicles. One of them is to in a frequency band, which is discussed in this paper through topology optimization aiming at resonance sound radiation in thermal environments. The sound radiation at resonance fre- quencies is the main component of response, minimization on which is likely to provide a satisfactory design. A bi-material plate subjected to uniform temperature rise and excited by harmonic loading is studied here. Thermal stress is first evaluated and considered as prestress in the following dynamic analysis; radiated sound power is then calculated through Rayleigh inte- gral. Sensitivity analysis is carried out through adjoint method considering the complicated relationship between stress-induced geometric stiffness and design variables. As the resonance frequency is constantly changing during the optimization, its sensi- tivity should be considered. It is also noticed that mode switching may occur, so mode tracking technique is employed in this work. Some numerical examples are finally discussed.