Semi-analytical Vibration Characteristics of Rotating Timoshenko Beams Made of Functionally Graded Materials

AbstractFree vibration analysis of rotating functionally graded (FG) thick Timoshenko beams is presented. The material properties of FG beam vary along the thickness direction of the constituents according to power law model. Governing equations are derived through Hamilton's principle and they are solved applying differential transform method. The good agreement between the results of this article and those available in literature validated the presented approach. The emphasis is placed on investigating the effect of several beam parameters such as constituent volume fractions, slenderness ratios, rotational speed and hub radius on natural frequencies and mode shapes of the rotating thick FG beam

Design and energy saving analysis of a novel isobaric compressed air storage device in pneumatic systems

Compared with traditional isochoric storage of compressed air in pneumatic systems, isobaric storage possesses many advantages. In this study, a novel isobaric compressed air storage device is proposed by introducing compressed gas energy storage and a nonlinear cam transformation mechanism. The critical profiles on both sides of cam are deduced and the mathematical model of a typical pneumatic system is established under different control modes. A parametric analysis is also conducted to reveal how the energy-saving performance can be affected by several factors. The results show that this new isobaric compressed air storage device presents favorable constant-pressure characteristic and energy-saving performance. With a pneumatic system working pressure of 0.4 MPa, 18% energy savings can be achieved and the compressed air pressure is stable within 2.14%. The working pressure of system has a significant effect on the energy-saving performance and the energy-saving rate decreases with the increasing working pressure. The proposed novel isobaric compressed air storage device provides a new way to reduce pressure and energy consumption of pneumatic systems