Analysis of vibration characteristics based on variable‐angle hybrid laminates

Abstract

Composite laminates are widely used in the aerospace field. Aircraft wings are subject to strong aerodynamic interference, which produces resonance, instability and other phenomena. To avoid this resonance and reduce the vibration of laminates it is essential to adopt a variable‐stiffness laminate. Methods for changing the stiffness include designing the fiber path and inserting a damping layer. The former can increase the natural frequency but does not improve the damping performance. Here we demonstrate how, depending on the resin's agglomeration, variable‐angle hybrid laminates made of carbon fiber and Kevlar fiber increase the damping performance. By using a short beam shear test we found that sandwich hybrid samples with a hybrid ratio of 50% performed better than inter‐laminar hybrid samples, which increased by 19.5%. Based on the results of interlayer properties, 8 layers of pure carbon fiber (CF) laminates and carbon fiber‐kevlar fiber (CF‐KF) hybrid laminates with variable angles were manufactured. Modal tests demonstrated that the change in fiber angle had a greater impact on the natural frequency, the maximum result of which was seen at an angle of <60|75>. By inserting, the KF layer the damping ratio of the <15|30> hybrid laminate increased by 5.45% more than pure CF laminates. These results can be referenced to improve the damping parameters of variable‐angle laminates.

Study on durability of transverse shear properties for novel carbon/glass hybrid fiber‐reinforced polymer bars in simulated concrete environments

“…Although some remedial measures have been adopted to alleviate the problem of steel bar corrosion, [5][6][7][8][9] the results obtained are unsatisfactory. [10,11] Nevertheless, the development of fibrous composites with corrosion resistance has made significant progress so far, [12][13][14][15][16][17] wherein hybrid fiber-reinforced polymer (HFRP) bar possesses the outstanding advantages of tensile ductility, light weight, and high strength so that it is expected to be an alternative for the steel bar. [18] HFRP bar is composed of matrix resin and at least two continuous fibers with different stiffnesses.…”