The absorption of sound in the low frequency range is problematic with fibrous materials made up of coarser fibers. In that case, highly efficient sound absorption materials from much finer fibers must be developed. A...The absorption of sound in the low frequency range is problematic with fibrous materials made up of coarser fibers. In that case, highly efficient sound absorption materials from much finer fibers must be developed. Although studies on the acoustic properties of conventional textile materials started in the nineties, analysis of the acoustic properties of the electrospun nanofibrous membranes is a novel subject. Nanofibrous membranes can improve acoustic insulation products by increasing the sound absorption coefficient, reducing material thickness, and decreasing material weight offering a competitive advantage. The purpose of this study is to analyze the effect of fiber diameter on the acoustic behavior of nanofibrous membranes.展开更多
Nowadays, carbon fiber composite material is becoming more and more popular in aero engine industry due to its high specific strength and stiffness. Laminate carbon fiber composite material is widely used to manufactu...Nowadays, carbon fiber composite material is becoming more and more popular in aero engine industry due to its high specific strength and stiffness. Laminate carbon fiber composite material is widely used to manufacture the high load wide chord fan blade, containment casing, etc. The aeroelastic behavior of composite product is critical for the optimization of the product design and manufacturing. In order to explore its aeroelastic property, this paper discusses the coupled simulation of aerodynamic excitation applied on laminate composite material plate. Mechanical behavior of composite material plate is different from that of isotropic material plate such as metal plate, because it is anisotropy and has relative high mechanical damping due to resin between plies. These plates to be studied are designed using 4 different layup configurations which follow the design methods for composite fan blade. The numerical simulation of force response analysis mainly uses single frequency mechanical force input to simulate the electromagnetic shakers or other actuators, which could transmit mechanical force to the test parts. Meanwhile, pulsed air excitation is another way to "shake" the test parts. This excitation method induces aero damping into the test part and simulates the unsteady flow in aero engine, which could cause aeroelastic problems, such as flutter, forced response and non-synchronous vibration(NSV). In this study, numerical simulation using coupled method is conducted to explore the characteristics of laminate composite plates and the property of aerodynamic excitation force generated by pulsed air jet device. Modal analysis of composite plate shows that different ply stacking sequences have a significant impact on the plate vibration characteristics. Air pulse frequency and amplitude in flow field analysis are calibrated by hot wire anemometer results. As the air pulse frequency and amplitude are varied, incident angle of flow and layup configurations of plate can be analyzed in details by the simulations. Through the comparisons of all these factors, air pulse excitation property and the aeroelastic behavior of composite material plate are estimated. It would provide a possible way to guide the next-step experimental work with the pulsed air rig. The new composite fan blade design can be evaluated through the process.展开更多
文摘The absorption of sound in the low frequency range is problematic with fibrous materials made up of coarser fibers. In that case, highly efficient sound absorption materials from much finer fibers must be developed. Although studies on the acoustic properties of conventional textile materials started in the nineties, analysis of the acoustic properties of the electrospun nanofibrous membranes is a novel subject. Nanofibrous membranes can improve acoustic insulation products by increasing the sound absorption coefficient, reducing material thickness, and decreasing material weight offering a competitive advantage. The purpose of this study is to analyze the effect of fiber diameter on the acoustic behavior of nanofibrous membranes.
文摘Nowadays, carbon fiber composite material is becoming more and more popular in aero engine industry due to its high specific strength and stiffness. Laminate carbon fiber composite material is widely used to manufacture the high load wide chord fan blade, containment casing, etc. The aeroelastic behavior of composite product is critical for the optimization of the product design and manufacturing. In order to explore its aeroelastic property, this paper discusses the coupled simulation of aerodynamic excitation applied on laminate composite material plate. Mechanical behavior of composite material plate is different from that of isotropic material plate such as metal plate, because it is anisotropy and has relative high mechanical damping due to resin between plies. These plates to be studied are designed using 4 different layup configurations which follow the design methods for composite fan blade. The numerical simulation of force response analysis mainly uses single frequency mechanical force input to simulate the electromagnetic shakers or other actuators, which could transmit mechanical force to the test parts. Meanwhile, pulsed air excitation is another way to "shake" the test parts. This excitation method induces aero damping into the test part and simulates the unsteady flow in aero engine, which could cause aeroelastic problems, such as flutter, forced response and non-synchronous vibration(NSV). In this study, numerical simulation using coupled method is conducted to explore the characteristics of laminate composite plates and the property of aerodynamic excitation force generated by pulsed air jet device. Modal analysis of composite plate shows that different ply stacking sequences have a significant impact on the plate vibration characteristics. Air pulse frequency and amplitude in flow field analysis are calibrated by hot wire anemometer results. As the air pulse frequency and amplitude are varied, incident angle of flow and layup configurations of plate can be analyzed in details by the simulations. Through the comparisons of all these factors, air pulse excitation property and the aeroelastic behavior of composite material plate are estimated. It would provide a possible way to guide the next-step experimental work with the pulsed air rig. The new composite fan blade design can be evaluated through the process.
