考虑温度影响的重组竹材短期压缩蠕变性能研究

Study on Short-Term Compressive Creep Properties of Reconstituted Bamboo Considering Temperature Effects

  • 摘要: 本研究采用蠕变试验机对不同温度(10~70℃)下重组竹材进行6小时的短期压缩蠕变试验,分析了温度对其粘弹性蠕变性能的影响,采用Burgers模型与Findley模型,定量分析了温度对蠕变应变、速率及变形组分的调控机制。研究发现:在10至40℃区间内,蠕变增长相对平缓,而当温度超过50℃时,蠕变速率呈指数级增长,试件出现显著屈曲破坏。Burgers模型拟合的修正决定系数均高于0.90,表明其能有效描述重组竹的粘弹性蠕变特性,而Findley模型可作为工程简化估算的可靠工具。研究进一步揭示,温度升高导致弹性变形占比降低,从79.5%降至61.1%,黏弹性和黏性变形占比显著增加,分别增长1.298倍和1.191倍,且50℃附近半纤维素的玻璃化转变引发材料软化效应。时温等效原理表明,20~40℃区间符合Arrhenius方程,而40℃以上需引入分数阶导数模型修正非线性蠕变行为。研究成果可为重组竹结构在温变环境下的长期变形预测及安全使用提供参考依据。

     

    Abstract: In this study, short-term compressive creep tests were performed on reconstituted bamboo specimens at varying temperatures (10~70℃) over a 6-hour duration using a creep rheometer. The Burgers model and Findley model were employed to quantitatively analyze the regulatory mechanisms of temperature on creep strain, rate, and deformation components. Results indicate that within the 10~40℃ range, creep growth remained relatively gradual. However, when temperatures exceeded 50℃, the creep rate increased exponentially, accompanied by significant buckling failure in specimens. The Burgers model demonstrated high accuracy with adjusted coefficients of determination exceeding 0.90, effectively characterizing the viscoelastic creep behavior of reconstituted bamboo, while the Findley model proved reliable for simplified engineering estimations. Further analysis revealed that elevated temperatures reduced the proportion of elastic deformation from 79.5% to 61.1%, with notable increases in viscoelastic and viscous deformation components by 1.298 times and 1.191 times, respectively. The softening effect observed near 50℃ was attributed to the glass transition of hemicellulose. Time-temperature equivalence analysis showed that the Arrhenius equation governed creep behavior within 20~40℃, whereas a fractional derivative model was required to correct nonlinear creep behavior above 40℃. These findings provide critical insights for predicting long-term deformation and ensuring the safe application of reconstituted bamboo structures in temperature-varying environments.

     

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