风载荷对单株谷子茎秆变形的影响

Effect of wind load on the deformation of single millet stems

[目的]风载荷是影响谷子倒伏的重要因素之一,该研究旨在通过分析风载荷对不同品种谷子茎秆的力学特性关系,研究风速、谷子品种对茎秆变形量、倒伏角度的影响。[方法]于2023年开展室内风载试验,研究了‘张杂谷16号’‘长杂谷466号’和‘晋谷21号’单株茎秆在不同风速下的变形规律。[结果]风速、品种对谷子茎秆水平变形量的影响均显著,且风速的影响大于品种;同一品种谷子茎秆的水平变形量随着风速的增加而增加,随谷子茎秆高度的增加而增加,最大变形量出现在茎秆顶端;同一风速作用下,不同品种谷子茎秆的变形量不同,晋谷21号变形量最大,最大值在风速为6 m·s^(-1)时达到26.45 cm,张杂谷16号变形量最小,最小值在风速为2 m·s^(-1)时达到1.64 cm。风荷载作用下茎秆的力学模型简化为一端固定一端约束,一端自由的等截面弹性杆在轴向压力、侧向均布载荷及杆自由端弯矩作用下的纵横弯曲模型,茎秆水平变形量可用二次多项式拟合。根据倒伏角度与风速之间的关系,预测不同品种的茎秆抗倒伏风速,张杂谷16号发生倒伏的临界风速为8.51 m·s^(-1),长杂谷466号发生倒伏的临界风速为9.34 m·s^(-1),晋谷21号发生倒伏的临界风速为6.96 m·s^(-1)。[结论]谷子茎秆在风载荷作用下变形受风速与品种影响,不同品种谷子倒伏的临界风速不同。该研究为不同品种谷子的抗风载荷性能提供理论依据。

[Objective]Wind load is an important factor influencing millet lodging.The purpose of this study was to analyze the mechanical properties of millet stems under different wind loads and examine the effects of wind speed and millet varieties on stem deformation and lodging angle.[Methods]Indoor wind load tests were carried out in 2023 to investigate the deformation patterns of individual stems from three millet varieties:Zhangza 16,Changza 466,and Jingu 21,under different wind speeds.[Results]The results showed that both wind speed and variety significantly affected the horizontal deformation of millet stems,and the wind speed showed a greater influence than varieties.The horizontal deformation of millet stems within the same variety increased with higher wind speeds,and the maximum deformation occurred at the top of the stem as stem height increased.Under the same wind speed,different varieties exhibited varying deformation patterns,and Jingu 21 showed the highest deformation reaching a maximum of 26.45 cm at wind speed of 6 m·s^(-1) and a minimum of 1.64 cm at 2 m·s^(-1).The deformation behavior of millet stems under wind loading could be modeled by a quadratic polynomial.The mechanical model described the stem as an isotropic elastic rod with one end fixed and the other end free,subjected to axial pressure,lateral uniform load,and a bending moment at the free end.Based on the relationship between lodging angle and wind speed,the critical wind speed for lodging resistance of different cultivars was determined to be 8.51 m·s^(-1) for Zhangza 16,9.34 m·s^(-1) for Changza 466,and 6.96 m·s^(-1) for Jingu 21.[Conclusion]Millet-stem deformation under wind load is influenced by wind speed and varieties,with each variety having a distinct critical wind speed for lodging resistance.The study provided a theoretical basis for improving the wind resistance of different millet varieties.