Search

In recent times, origami-inspired deployable structures have received significant interest from the research community as a major area of research in the fields of science and technology. This paper deals with the geometry and the deformation behavior of deployable cones based on the four-fold line origami concept. First, a novel geometric design algorithm is presented to develop axially foldable conical structures based on generalized Miura-ori pattern, which is then utilized to investigate the influence of four design parameters on folding geometry. The foldability of thus obtained origami patterns is verified with the help of physical models. The geometric incompatibilities during the deployment are highlighted using a simple experiment, showing the unfolding sequence of a paper model. The deformations due to incompatibilities are analyzed by adopting the concept of pin-jointed truss modeling of the origami structures. A mathematical model of the deployment problem is formulated to capture the deployment deformations of the structure, on the basis of which an algorithm for deformation analyses is developed. One example is considered to characterize the deformation behavior of the conical origami structures as the design parameters of the folding pattern are varied. The analytical findings demonstrate that the fold line strains of the origami cone are very sensitive to the changes in three design parameters, number of origami units (m), fold angle (α 0), and angle θ 2 ; except the length ratio (l r 0). The variation in design parameters may induce bi-stability in the deployment path of the conical structure. The findings of the analytical investigation are verified numerically, demonstrating that the strain responses obtained from the numerical analyses are completely consistent with the analytical results. [ABSTRACT FROM AUTHOR]

Abstract: A combined energy and attitude control system (CEACS) is a hybrid system that uses flywheels to store energy and provide a simultaneous attitude control in satellites. Previous work appeared in Advances in Space Research (ASR) employing the proportional-derivative (PD) control has proven that CEACS works well and achieves its mission requirement. However, the in-orbit system performance uncertainties present a challenge to the CEACS attitude pointing capability. Thus, this paper complements the previous mentioned work, and focuses on employing the H∞ optimal attitude control solution for the CEACS attitude control enhancement. The mathematical model and numerical treatments for the CEACS H∞ control architecture are presented. Numerical results show that a better attitude pointing accuracy at least up to 0.043° can be achieved with the H∞ control method. [Copyright &y& Elsevier]

Abstract: The issue considered in this paper is the dynamic behavior of flexible probe based on space probe-cone docking mechanism in the docking process. The theoretical model of docking impact dynamics based on flexible beam is built according to the Lagrange Analytical Mechanics theory. The contact problem is solved by using Hertz point-surface contact model. Assumed Modes Method is introduced to describe the deformation of flexible beam. Runge–Kutta numerical method is used to solve this theoretical model. Results of the theoretical model show a good agreement with the experimental and MSC.Patran/Dytran simulation results. Moreover, the influence of flexible beam parameter on docking impact process is analyzed based on the theoretical model. [Copyright &y& Elsevier]

Abstract: Based on the author’s experience in ISO TC20/SC14 Working Group 4, this paper discusses the common problems encountered when developing a standard for solar energetic particle (SEP) fluxes. The problem involving the reliability of the distribution function describing the SEP events and the interpolation of this function into the region of not-yet-observed large events are discussed. The problems with describing the fluences of SEPs over a wide range of energy in the form of energetic spectra are analyzed. Requirements for SEP flux models are formulated. The reliability of some SEP flux models is determined by comparing their predictions with the experimental data. [Copyright &y& Elsevier]