This work investigates the primary resonance and internal resonance of a double-section beam with cubic nonlinearities. This model can be applied in a wide range of engineering problems, such as rocket and missile structures. Even space technology has been developed for decades; several nonlinear properties deserve further study, especially, for the internal resonance. The method of multiple scales (a perturbation technique) is employed to analyze this nonlinear problem. This study focuses on finding the forcing conditions of this 3D double-section beam to trigger the often-ignored internal resonance or prime resonance in rocket structures. A primary resonance is found on a uniform free-free beam at certain flight speed. The three-to-one internal resonance of the double-section beam occurs within the first and the second modes in the diameter ratio of 1/0.75 with the length ratio of 0.33 or 0.51. The semi-analytical results are verified by the time marching numerical method.
To obtain the dynamic driving parameters for cholesteric LCD in a systematic manner, its dynamic characteristics and then driving parameters should be measured and extracted respectively. Accordingly, this paper develops a real‐time dynamic characteristics measurement system and an automatic dynamic driving parameters extraction scheme. Satisfactory results can be obtained experimentally.
Fast refresh rate is desirable for inherently slow updated passive matrix (PM) cholesteric liquid crystal display (Ch-LCD). This paper proposes a flexible cumulative drive scheme for fast and optimally refreshed PM Ch-LCD. The proposed drive scheme was experimentally verified on a 5" 100ppi PM Ch-LCD and satisfactory results were obtained.
To reduce the power consumption and improve the image quality of a full color Cholesteric LCD, low driving voltage Cholesteric LC and crosstalk-free drive schemes have been respectively developed. The developed technologies were integrated into a 5" full color QVGA Cholesteric LCD with a low-cost single-layer structure. The performance of the display validated the development approaches.
Two damping rings (DRs) are added on a nonlinear free-free elastic beam to reduce vibrations. This elastic beam with free-free boundary conditions can be used to simulate the high speed aircraft fuselage vibrations. Both isotropic beam and compound beam with double-section are investigated. The beam is subjected to a distributed load with the harmonic wind force. The method of multiple scales ((MOMS) a perturbation technique) is employed to analyze this nonlinear problem in frequency domain. DRs with various locations, masses, spring constants, and damping coefficients are analyzed and the maximum amplitude counter plots (MACPs) are compiled to identify DRs’ combinations for the optimal damping effects. The Floquet theory is used to make the basin of attraction (BOA) charts and analyze the stability of the system. This research can be applied in a wide range of engineering problems, such as rocket structures, high-speed aircrafts, satellites, missiles, etc.
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