Optimization of Sound Transmission Loss through a Thin Functionally Graded Material Cylindrical Shell

Table 1

Material and environmental properties.

Material	Shell materials					Cavity	Ambient
	Aluminum	Steel	Nickel	Zirconia	Brass	Air	Air
𝜌 (kg/m^3)	2760	7750	8900	5700	8500	2.9	2.9
𝐸 (Gpa)	72	210	224	244	104	—	—
𝜐	0.33	0.3	0.34	0.3	0.37	—	—
Sound speed (m/s)	—	—	—	—	—	340	340
Incident angle (deg.)	45
Shell radius (m)	1.5
Shell thickness (mm)	1.5
𝑚0 (kg/m)	6.21 (1.5×𝑚Al.)