High aspect ratio wing (HARW) structures will deform greatly under aerodynamic loads, and changes in the stiffness will have a great impact on the flutter characteristics of such wings. Based on this, this paper presents an effective method to determine the effect of the stiffness on the flutter characteristics of HARWs. Based on the calculation theory of the mechanical profile of thin-walled structures, the torsional stiffness and bending stiffness of the wing are obtained through calculation. We use the fluid-structure coupling method to analyze the flutter characteristics of the wing, and we use our research results based on the corotational (CR) method to perform structural calculations. The load is calculated using a computational fluid dynamics (CFD) solver. The results show that, compared with the original wing, when the bending stiffness and torsional stiffness of the wing along the spanwise direction increase by 8.28% and 5.22%, respectively, the amplitude of the flutter decreases by approximately 30%. Increasing the stiffness in the range of 0.4 to 0.6 Mach has a greater impact on the flutter critical velocity, which increases by 12.03%. The greater the aircraft’s flight speed is, the more severe the stiffness affects the wing limit cycle oscillation (LCO) amplitude.

The traditional camouflage way is only used to camouflage the military objectives in the fixed background. As the seasons and temperature change, the background color is undergoing tremendous changes. To solve this problem, a new kind of intelligent camouflage coating was invented whose color changes with the temperature and blends with the background. Through orthogonal design and experiments, the composition of raw materials and mixture ratio has been determined. The physical and chemical performances of the coating such as drying time and color-changing temperature have been tested. The result shows that the coating has good coating effect, excellent mechanical and chemical performance which can meet the camouflage requirements of changing seasons.

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The fatigue of grid structures with welded hollow spherical joint under suspending cranes is an issue in both academic and engineering fields at home and abroad. The structural fatigue is mainly caused by the fatigue failure of welded hollow spherical joint with cross-board. In this paper, 16 specimens categorized in KQ-4、KQ-5 and KQ-7were tested stably and efficiently under constant amplitude stress by use of self-designed loading equipment. The testing results show that the form and mechanism of fatigue failure were clarified elementarily. A fatigue curve of welded hollow spherical joint with cross-board, S-N curve, was suggested in this paper based on the statistic regression analysis of the 16 testing results. The constant amplitude fatigue calculation method was established for welded hollow spherical joint with cross-board in grid structure with welded hollow spherical joint by use of allowable stress amplitude method.

This paper takes a large supermarket as the research object. Based on its adding layer directly without identification, these implementations including reviewing design drawing, witnessed inspections, indoor test and theoretical analysis are carried. The identification results show that: the layer-adding design has a serious problem on the conception; part of the foundation's short concrete column misplaced seriously to its upper concrete column whose maximum is up to 50mm, and between the gap, there are some obvious weak positions existing some crossing pipelines which are filled completely with cement mortar; part of the concrete column's tails have serious phenomenon of cellular pits; the upper steel structure's support system is imperfect and unreasonable; the seismic capability of the blindly adding layer structure could not meet the national code's requirements. Based on the above structure defects, this paper ensure the safety of the adding layer structure through sticking steel's reinforcement method, section enlargement method and adding some structure 's support system.