Study of the compressive creep performance of the recombinant bamboo based on the Kelvin-Voight model and the theory of variable-order fractional derivative

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ABSTRACT For natural fiber-reinforced composite materials such as recombinant bamboo, the obvious creep phenomenon can generally be found under the static load and room temperature. In this study, the compressive creep property of this material was selected as the research object. First, the compressive strength of the material was determined using standard compressive fracture experiments and statistical analysis. Then, the compressive creep experiment was carried out on four groups of specimens according to a time-varying compressive load defined based on the strength parameter obtained in the previous step. Finally, different kinds of viscoelastic mechanical constitutive relationship models were chosen to analyze the creep strain evolution process. The main conclusion drawn from the research is that the stress level applied to the specimen affects the creep strain evolution process. In addition, compared with the traditionally defined Kelvin-Voight model, the R-L fractional derivative defined Kelvin-Voight model proposed in this paper can accurately simulate the compressive creep evolution process of the recombinant bamboo under various load conditions. The influence of the stress level on the main model parameters can be expressed clearly, which makes the model suitable to be adopted in the design and application of the material in actual engineering.