Strength and dynamic characteristics analyses of wound composite axial impeller

Abstract

A low cost, light weight, high performance composite material turbomachinery impeller with a uniquely designed blade patterns is analyzed. Such impellers can economically enable refrigeration plants to use water as a refrigerant (R718). A strength and dynamic characteristics analyses procedure is developed to assess the maximum stresses and natural frequencies of these wound composite axial impellers under operating loading conditions. Numerical simulation using FEM for two-dimensional and three-dimensional impellers was investigated. A commercially available software ANSYS is used for the finite element calculations. Analysis is done for different blade geometries and then suggestions are made for optimum design parameters. In order to avoid operating at resonance, which can make impellers suffer a significant reduction in the design life, the designer must calculate the natural frequency and modal shape of the impeller to analyze the dynamic characteristics. The results show that using composite Kevlar fiber/epoxy matrix enables the impeller to run at high tip speed and withstand the stresses, no critical speed will be matched during start-up and shut-down, and that mass imbalances of the impeller shall not pose a critical problem.

Effect of environmental degradation and mechanical properties of polyamide 6-grafted carbon fiber/poly(3-hydroxybutyrate-co- 3-hydroxyvalerate) composites

“…Thus, though the interfacial bond may be poor, the interface could transfer load more effectively, resulting in the enhancement of their hardness. [11][12][13] The effect of water absorption on the tensile strength of CF/EPDM composites with PA6 fiber loadings at 20 C for melt mixed for different periods of time is depicted in Figure 4. It was found that at all fiber loadings, the composite tensile strength decreased with increase in immersion time.…”

Hollow interference fitted multi-ring composite rotor of the superconducting attitude control and energy storage flywheel

“…By increasing the mesh density step by step, a suitable number of elements are obtained. 39 There are totally 75,132 nodes and 77,256 elements generated by dividing the composite rotor along its radial and circumferential direction. Because of the orthotropic properties of the composite material, cylinder element coordinate system is set in the FE model.…”

“…Tzeng and Moy 37 designed a composite energy storage flywheel for fatigue crack resistance. Wang et al 38,39 researched the stress and dynamic characteristics of the wound composite material axial impeller under centrifugal force loading conditions based on finite element analysis. By addition of resin acceptor to improve the interface state between fiber and matrix of resin or by modification of epoxide resin to improve the radial strength of the solidified resin to some extent, some regarded the radial structure of composite rotor as cascade model with fiber, interface and matrix to find methods to increase the SED but these methods cannot improve the radial strength of the monodirectional composite material greatly.…”

“…By addition of resin acceptor to improve the interface state between fiber and matrix of resin or by modification of epoxide resin to improve the radial strength of the solidified resin to some extent, some regarded the radial structure of composite rotor as cascade model with fiber, interface and matrix to find methods to increase the SED but these methods cannot improve the radial strength of the monodirectional composite material greatly. 29,30,[32][33][34][35][36][37][38][39][40][41][42][43][44] Some attempts were made to make the flywheel using metallic matrix composite material and while its radial strength was improved effectively, its circumferential strength reduced greatly in contrast with that of the reinforced resin matrix composite fiber rotor. 32 Generally, the most effective way to reduce the maximum radial stress is making the formed composite rotor be in high compressive pre-stress state by multiring interference fitting or applying large enough tension force to the fiber bundle during the rotor winding processing.…”

“…For a discal rotor, the SED of the thin rim type rotor is the highest and the hollow or approximate hollow rotor can to some extent change the distribution of the centrifugal stress and reduce the maximum radial stress of the rotor at a high rotary speed. Based on the achievements of Ha, 29,30,32–36 Qin 37–45 and others, we present a novel hollow interference fitted multi-ring composite rotor without shaft for superconducting ACESF to simplify its fabrication and to maximize its SED at a reasonable speed. The research emphasize on the analysis of stress distribution inside the interference fitted multi-ring composite rotor by mathematical method and finite element analysis method and its main factors affecting the stress distribution are also analyzed in depth.…”