“…In Refs. 20,21 and 37, it has been proved that the increased temperature results in decreased composite stiffness, the decreased stiffness produces reduced resonance frequencies, and the reduced resonance frequencies induce the decreasing of STL peak/dip frequencies. Hereby, the reason is verified via experiments shown in Figure 20.Figure 20.Measurement of elastic modulus.…”
Section: Verification and Analysis Of Experimental Resultsmentioning
confidence: 99%
“…Li 19,20 studied sandwich panels’ STL in a thermal environment using the mode superposition method and presented an analytical method for sandwich panels in thermal environments. Then, Zhou 21 investigated the sound radiation of porous functionally graded material (FGM) plates with a temperature gradient along with the thickness. Recently, Hu 22 proposed a semi-analytical model to analyze FGMs’ STL.…”
An improved sound transmission loss (STL) experimental technique based on the sound pressure method (SPM) and acoustic box method is proposed to investigate the temperature influence on the STL of the ribbed carbon fiber reinforced plastics aircraft panel. SPM principle is given. The measurement procedure of the improved STL technique is presented and its reliability is verified. STL variable characteristics of the panel within −40°C–40°C were measured. Results showed that temperature had a significant effect on the panel’s STL. The overall STL varied nonlinearly with temperature, whereas STL exhibited a fluctuation or monotony trend at a single center frequency. Temperature variation caused changes of STL peak/dip frequencies and redistribution of stiffness-controlled, resonance-controlled, coincidence-controlled, and damping-controlled regions. The causes of the aforementioned are given. This study reveals the relationship between temperature, thermomechanical parameters and STL. The findings have applications in the design, measurement, analysis, and theoretical development of composite structure acoustics.
“…In Refs. 20,21 and 37, it has been proved that the increased temperature results in decreased composite stiffness, the decreased stiffness produces reduced resonance frequencies, and the reduced resonance frequencies induce the decreasing of STL peak/dip frequencies. Hereby, the reason is verified via experiments shown in Figure 20.Figure 20.Measurement of elastic modulus.…”
Section: Verification and Analysis Of Experimental Resultsmentioning
confidence: 99%
“…Li 19,20 studied sandwich panels’ STL in a thermal environment using the mode superposition method and presented an analytical method for sandwich panels in thermal environments. Then, Zhou 21 investigated the sound radiation of porous functionally graded material (FGM) plates with a temperature gradient along with the thickness. Recently, Hu 22 proposed a semi-analytical model to analyze FGMs’ STL.…”
An improved sound transmission loss (STL) experimental technique based on the sound pressure method (SPM) and acoustic box method is proposed to investigate the temperature influence on the STL of the ribbed carbon fiber reinforced plastics aircraft panel. SPM principle is given. The measurement procedure of the improved STL technique is presented and its reliability is verified. STL variable characteristics of the panel within −40°C–40°C were measured. Results showed that temperature had a significant effect on the panel’s STL. The overall STL varied nonlinearly with temperature, whereas STL exhibited a fluctuation or monotony trend at a single center frequency. Temperature variation caused changes of STL peak/dip frequencies and redistribution of stiffness-controlled, resonance-controlled, coincidence-controlled, and damping-controlled regions. The causes of the aforementioned are given. This study reveals the relationship between temperature, thermomechanical parameters and STL. The findings have applications in the design, measurement, analysis, and theoretical development of composite structure acoustics.
“…Parametric effects of plate variables (such as power-law index, modulus ratio, and damping loss factor) on the vibroacoustic response of a clamped, thin power-law index, functionally graded plate under point forcing are discussed. Researchers estimated that the sound radiation response of isotropic [4][5][6][7][8][9][10][11], orthotropic [12][13][14][15], composite [16][17][18], sandwich plates [19][20][21], and FGM [22][23][24][25][26][27][28][29] plates using the Rayleigh integral method. The authors used the elemental radiator approach to estimate the sound power radiated by plate structures [13,[29][30][31][32][33][34][35][36][37][38].…”
Section: Introductionmentioning
confidence: 99%
“…They investigated the sound transmission and reflection from unbounded panels of functionally graded materials. Zhou et al [27] examined temperature-dependent porous functionally graded plate for vibration and sound radiation. They used first-order shear deformation theory with the temperature-dependent material properties to formulate the governing equation of porous FGM plates using Hamilton's principle and demonstrated that structural stiffness and rigidity played a significant role in the dynamics and acoustics response of porous FGM plates.…”
This paper analyzes the sound radiation behavior of a clamped thin, functionally graded material plate using the classical plate theory and Rayleigh Integral with the elemental radiator approach. The material properties of the plate are assumed to vary according to the power-law distribution of the constituent materials in the transverse direction. The functionally graded material is modeled using a physical neutral surface instead of a geometric middle surface. The effects of the power-law index, elastic modulus ratio, different constituent materials, and damping loss factor on the sound radiation of functionally graded plate are analyzed. It was found that, for the considered plate, the power-law index significantly influences sound power level and radiation efficiency. There exists a critical value of the power-law index for which the corresponding peak of sound power level is minimum. In a wide operating frequency range, approximately 500–1500 Hz, this research suggests that the radiation efficiency is lower for the power-law index equal to 0 and 1. However, for very low frequencies (less than 250 Hz), the power-law index does not affect radiation efficiency significantly. Further, as the modulus ratio increases, the sound power peak decreases for a given power-law index. For the given material constituents of the functionally graded plate, the different values of damping loss factors do not significantly influence radiation efficiency. However, the selection of material constituents affects the radiation efficiency peak.
“…For both monolithic and FG plates, the effects of elastic-constraint boundary conditions on plate vibration have already been analyzed. [20][21][22][23][24][25][26][27][28][29][30] However, for an FG plate constrained elastically at its edges by springs, [29,30] how its frequency parameters change under varying temperature environments remains elusive.…”
An analytical method for free vibration of functionally graded (FG) plates with arbitrary boundary conditions in thermal environments is developed based on 3D elasticity theory. Material properties of the FG plate are assumed to be temperature dependent but graded along with its thickness. At the edges of the plate, three different sets of linear springs are introduced, so that its boundary condition can be altered by changing the spring stiffness. Each displacement component of the plate is expanded as a standard Fourier cosine series, supplemented with closed‐form auxiliary functions. With thermal environment effects duly accounted for, the energy method is used to derive eigenvalue equations, whereas the Rayleigh−Ritz procedure is utilized to calculate the natural frequencies of the FG plate. Numerical examples show that the present method converges quickly and gives satisfactory results. The method is then utilized to calculate the natural frequencies of FG plates having different aspect ratios, volume fractions, and elastic boundaries.
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