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This paper proposes a new algorithm to generate representative volume elements (RVEs) with random fiber distribution in fiber reinforced composites (FRC). The proposed algorithm is straightforward and easy to implement based on judging the maximum and minimum distances between a new fiber and existing fibers. The generation results demonstrate that the maximum fiber volume fraction gradually increases and oscillates violently before reaching 78.54% as the fiber radius rises. Moreover, with the increase of RVE size, the maximum fiber volume fraction changes gently when the fiber radius does not exceed 6.5 μm, but it changes dramatically at other fiber radii. Then, the fiber distributions of the generated RVEs are evaluated using the nearest neighbor distance, Ripley’s K function, and pair distribution function. The evaluation results indicate that the fiber distributions present randomness. Lastly, the effective elastic properties of the Carbon/Epoxy unidirectional FRC are predicted using the RVEs generated by the proposed algorithm, the RVEs generated by regularization, and the Mori–Tanaka method. It is found that the prediction using the RVEs generated by the proposed algorithm is more accurate than the regularization, compared with the Mori–Tanaka and experiment results. The proposed algorithm contributes to microstructure modeling in computational micromechanics.

Considering the influence of the fixing method of the component in the system on its results in ultrasonic infrared thermography testing, the detection experiments of the cracked plat structure with fixing at one end and fixing at two ends are carried out through different fixing methods of the equivalent structure. The results show that for the same structure to be detected, the more the bounds are fixed, the more the degrees of freedom are restricted, the less ultrasonic energy is dissipated during the inspection process, and the better the inspection effect. The work has positive significance for the selection of detection parameters in ultrasonic infrared thermography testing, helpful to provide some references for it.

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