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To address the fatigue life prediction problem of fiber-reinforced composite laminates, a method for predicting fatigue life was proposed by closely combining theory and simulation, unidirectional board and multi-directional laminate. Based on the fatigue test data of several sets of carbon fiber/resin-based T300/QY8911 unidirectional plates under cyclic stress, the fatigue life model and damage function of unidirectional plates were established by using the GM(1, 1) model of the gray system. Compared with the traditional least squares method fitting, this method improves the prediction accuracy. Stress analysis, failure analysis and material degradation of laminates were performed by finite element methods. The results of the failure analysis were combined with the established fatigue life model and damage function of the unidirectional laminate to calculate the fatigue life and damage of the multidirectional laminate. A comparison of the experimental data and those of other prediction methods indicates the prediction method established reduces the relative error of fatigue life prediction and the results predicted is in good agreement with the experimental results.

The effects of nano-SiO2 and its composites with polyamide 6 on the tribological properties of ultra-high molecular weight polyethylene (PE-UHMW) were investigated using electronic universal testing machine, M-2000 friction testing machine, electron and optical microscope. The results indicate that the friction coefficient and wear rate of PE-UHMW composites decreased at first and then tended to increase with an increase in the nano-SiO2 content. The composites exhibited the lowest friction coefficient and wear rate at a nano-SiO2 content of 2 wt%. When 8 wt% polyamide 6 was added into the PE-UHMW composite containing 2 wt% nano-SiO2, the composites obtained a low friction coefficient of 0. 29 and a low wear rate of 0. 33X10-9 g/(N•m). The wear mechanism analysis indicated that the addition of nano-SiO2 could effectively inhibit the adhesive wear and plastic deformation of PE-UHMW, and PE-UHMW composite with appropriate nano-SiO2 and polyamide 6 can form a more uniform and compact self-lubricating transfer film, and the wear surface becomes more smooth and present a very slight abrasive wear characteristics. [ABSTRACT FROM AUTHOR]