Study On Numerical Simulation Of The Plastic Air Intake Manifolds On Vibration Noise

Plastic air intake manifolds (PAIM) are successfully replacing aluminum air intake manifolds. Good performance, lower weight and costs are the main reasons behind this trend. However, PAIMs are often considered somewhat negative in terms of NVH performance since they are less stiff and less dense than aluminum manifolds. To better understand the acoustic performance of AIMs, this paper mainly researches on the dynamic characteristics of PAIMs and carries out noise prediction on the basis of numerical simulation method.Firstly, the dynamic characteristics of AIM are studied by performing a modal analysis in common software ANSYS. Then the noise characteristic of AIM due to engine gravity load is studied using the pseudo-excited method. A harmonic analysis is performed and the surface vibration is exported as the excitation for the subsequent acoustic analysis in SYSNOISE. Secondly, the noise prediction induced by inner pressure pulsation of AIM is researched. The measured air pressure pulsation is obtained in the crank-angle domain. This pressure is first transformed into time domain, and then read into MATLAB and transformed into frequency domain using fast Fourier transform. A coupled analysis in SYSNOISE is launched to couple the boundary element model and the finite element model of the structure. The computed surface vibration constitutes the excitation for the following acoustic analysis. Further analysis is made in detail based on the numerical results of the manifold-radiated noise, which is obtained from the acoustic analysis. Finally, modifications are made according to the analysis and a new model is established and analyzed.In this paper, the theory of virtual design and advanced integrated CAD/CAE optimal method are employed and simulation on the acoustic performance of AIMs is performed,which can reduce the cycle and cost of exploitation. The method developed is effective and feasible for plastic AIM design, and it is favorable for accelerating the plastic air intake manifold popularization in China.