Research on Mechanical Performance Parameter of Metal Rubber
Metal Rubber is special materials and used in aerospace, especially under extreme conditions. It has characteristics of strong adaptability, corrosion resistance, radiation resistance and designability. In this paper, we have manufactured Metal Rubber components, and done some research on the influence of previous deformation to Metal Rubber material's structure and performance, its characteristic parameters such as Poisson's ratio, Elastic modulus were studied. Research results are basic but essential for finite element analysis of Metal Rubber materials; these results also play an important role of engineering application.
Calculation of resonant sound absorption parameters for performance evaluation of metal rubber material
The first resonant (anti-resonant) frequency and sound absorption coefficient of metal rubber (MR) material are theoretically studied with hard backed samples and with air layer. The equations of the first resonant and anti-resonant frequencies of MR are deduced from the undamped propagation characteristics of porous material. The first resonant and anti-resonance sound absorption coefficients are induced according to the theoretical formula for the acoustic characteristic parameters of MR, and the former is modified while the energy consumption at resonance is taken into consideration. The good agreement between the calculation results of these resonant sound absorption parameters and the experimental results verifies the effectiveness of this calculation method for the performance evaluation of MR as a sound absorption material.
Behavior of rigid-porous layers at high levels of continuous acoustic excitation: theory and experiment.
A model for the propagation of high amplitude continuous sound through hard-backed rigid-porous layers has been developed which allows for Forchheimer's correction to Darcy's law. The nonlinearity associated with this is shown to be particularly important in the range of frequencies around layer resonance. The model is based on the introduction of particle velocity dependent flow resistivity into the equivalent fluid model expression for complex tortuosity. Thermal effects are accounted for by means of a linear complex compressibility function. The model has been used to derive analytical expressions for surface impedance and reflection coefficient as a function of incident pressure amplitude. Depending on the material parameters, sample thickness, and frequency range the model predicts either growth or decrease of reflection coefficient with sound amplitude. Good agreement between model predictions and data for three rigid-porous materials is demonstrated.