基于结构声强法的红枣树振动能量传递特性研究

Vibration Energy Transfer Characteristics of Jujube Trees Based on Structural Intensity Method

摘要:

为了研究红枣振动采收过程中能量在枣树中的传递特性及规律，提出了基于结构声强法的振动能量在枣树中传递的可视化分析方法，构建了红枣树结构声强矢量场分析模型，求解并可视化了不同激振条件下红枣树的结构声强矢量场。通过振动能量通量比量化分析表：在低频率振动 (1 阶、2 阶固有频率) 时，能量主要滞留在主干，随着频率升高 (3 阶、4 阶固有频率), 能量均匀地传递至红枣树各结构部位;在圆周激励或直线激励下，能量主要滞留在主干，而在非圆周激励或三维激励下，能量均匀地传递至红枣树各结构部位;随着激振时间增加，能量传递路径逐渐变化，但到 3s 后，传递路径趋于稳定;能量传递效果与激振高度呈正相关;激振力的变化不影响能量传递路径;对于高度相近的侧枝，能量传递效果与连接处截面积、侧枝长度呈正相关，与生长角度呈负相关;对于同侧侧枝，随着侧枝高度增加，能量传递效果与连接处截面积、侧枝长度呈负相关;对于生长角度相近的侧枝，能量传递效果与连接处高度呈正相关，与截面积、侧枝长度呈负相关;对于长度相近的侧枝，能量传递效果与连接处高度、生长角度呈正相关，与截面积呈负相关。并通过振动试验验证分析模型的相对误差在 7.3% 以内，表明该模型具有较高的可靠性。

Abstract:

Aiming to investigate the energy transfer characteristics and patterns of jujube trees during vibratory harvesting, a visualization analysis method for the structural intensity of jujube trees was proposed. By integrating ANSYS and self-developed Matlab programs, a structural intensity vector field analysis model for jujube trees was established, and the structural intensity vector field of jujube trees under different excitation conditions was solved and visualized. Quantitative analysis based on the vibrational energy flux ratio revealed the following: at low -frequeney vibrations (the Ist and 2nd natural frequencies), energy primarily remains in the trunk; as the frequeney inereases (the 3rd and 4th natural frequencies), energy was uniformly transferred to various structural parts of the jujube tree. Under circular or linear excitation, energy mainly stayed in the trunk, whereas under non-circular or threedimensional excitation, energy was evenly distributed to all structural parts of the jujube tree. As excitation time increased, the energy transfer path gradually changed, but it stabilized after 3 seconds. The energy transfer efficiency was positively correlated with excitation height. Changes in excitation force did not affect the energy transfer path. For side branches at similar heights, energy transfer efficiency was positively correlated with the cross-sectional area at the connection and the length of the side branch, but negatively correlated with the growth angle. For side branches on the same side, as the height of the side branch increased, energy transfer efficiency was negatively correlated with the cross-sectional area at the connection and the length of the side branch. For side branches with similar growth angles, energy transfer efficiency was positively correlated with the height of the connection point but negatively correlated with the cross-sectional area and the length of the side branch. For side branches of similar length, energy transfer efficiency was positively correlated with the height of the connection point and the growth angle but negatively correlated with the cross-sectional area. Vibration experiments verified that the relative error of the analysis model was within 7.3%, indicating high reliability.