The influence of structure parameters on mechanical properties of honeycomb sandwich mirror was investigated. Gibson hexagon equivalent theory, sandwich plate theory and Hoff theory were modified based on the theoretical analysis. The results were shown that structure parameters had non-linear influence on dimensionless structure tensile specific stiffness, shearing specific stiffness and bending stiffness in different direction while the honeycomb core was equivalent as solid material with modified material properties. The honeycomb mirror and equivalent model was modeled by using finite element method. The root mean square (RMS) and peak-to-valley (PV) values of mirror surface were determined under gravity with the optical axis pointed to the zenith. Compared with the actual modeling data, the relative error of equivalent results was less than 5%. And the optimal structure parameter range was obtained by these analyses.

In this paper, vibration attenuation characteristic of periodic composite pipeline is studied, focusing on the fluid structure interaction (FSI). Besides fluid velocity and pressure, Poisson coupling and friction coupling are also taken into consideration. A novel modified transfer matrix method (TMM) is proposed to investigate the distribution of band gap structures (BGs), and attenuation intensity within stop band frequency is also accurately predicted. BGs and Frequency response function for axial, transverse, torsional and their coupled modes are calculated and validated with each condition, and display excellent consistency with Shen’s results. In order to explore FSI effect of different models, pipe without fluid loading, with inner fluid taken as additional mass and pipe considering FSI effect are all presented. It is found that BGs with Bragg scattering mechanism are generated in all three models, but the distribution differs greatly, thus the FSI effect could not be ignored in practical engineering applications. The work in this paper provides novel method and useful reference for noise and vibration reduction of pipeline system conveying fluid.

Quasi-static indentation (QSI) tests on plain weave carbon fiber reinforced silicon carbide (C/SiC) ceramic matrix composites (CMC) have been performed to study the damage evolution law and damage modes. Acoustic emission (AE) and Ultrasonic C-scan techniques are creatively used to monitor the damage process and detect the indented damage, respectively. The damage development process could be described by three evidently different stages: initial crack tips spreading along within the matrix, matrix cracking and delamination as well as fiber bundles breakage of different layers. The AE activity indicated that the main damage modes are matrix cracking and delamination in the first two stages, once the pressing force exceeds the peak load the damage mode will change into fiber bundles breakage. Moreover, the damage procured in the QSI test is slightly lower than that produced in the low velocity impact (LVI) test under the equivalent energy, the correspondence between the two test methods is reasonably good.

The aim of this paper is to propose a microstructure modeling for prediction of thermal conductivity of plain weave C/SiC fibre bundles considering manufacturing flaws. Utilized photomicrographs taken by scanning electron microscope (SEM), an accurate representative volume element (RVE) model for carbon fiber bundles is established. Based on the steady-analysis method, the axial and transverse thermal conductivity of the carbon fibre bundles are calculated as 40.32Wm-1K-1 and 11.33 Wm-1K-1, respectively. The manufacturing flaws have different effects on thermal conductivity, the study shows that class A porosity has a significant effect on thermal conductivity, which leads to the thermal conductivity on the axial direction decrease by 13.31% and transverse direction decrease by 20.56% compared with no flaws RVE. While class B porosity has little influence on the k-value. The change law of axial and transverse thermal conductivity along with porosity volume is also observed: as porosity volume fraction is increasing, the thermal conductivity of fibre bundles shows significant linear decrease.

This paper discusses the unfolding form of the folding wing and its application to special UAV. The main investigations involve aspects such as unfolding process of the special UAV’s folding wing, contour structure of the complete unfolding, the choice of composite materials for the folding wing and its overall performance parameters. Modeling and dynamics analysis are made for all-composite wing through finite element analysis and calculating software. The unfolding process is also simulated. The result shows that the wing’s first-order frequency is low, second-order frequency and third-order frequency are close at different sweep angles. The wings are apt to happen flutter coupling in flutter analysis. With the continued folding of the wing, the wing’s natural frequency decreases significantly at different orders. The conclusions can provide effective basis for the study of wing rotational rate, unfolding time and impact action.