基于负泊松比结构的板簧压电称重传感器增敏设计

Sensitivity Enhancement Design of a Leaf-Spring Piezoelectric Weighing Sensor Based on an Auxetic Structure

摘要: 针对传统板簧压电称重传感器输出信号较弱、灵敏度受板簧表面自然应变限制的问题，本文提出一种基于负泊松比结构的板簧压电称重传感器增敏设计方法。在不改变板簧主体结构和不削弱其承载能力的前提下，将凹入六边形负泊松比结构作为应变放大附件布置于板簧表面应变较大的区域，利用其拉胀效应实现板簧弯曲变形向压电薄膜有效应变的转换与放大。首先建立半板簧有限元模型，分析板簧在动态载荷作用下的应变分布，并确定压电薄膜的优先布置位置；随后对负泊松比结构的几何参数进行分析，建立板簧–负泊松比结构–压电薄膜耦合模型，研究其应变放大效果和电压输出特性。仿真结果表明，在0~10 t载荷和1~10 Hz频率范围内，压电薄膜输出电压与载荷质量保持良好的线性关系。与传统直接贴片方式相比，负泊松比结构能够显著提高压电薄膜的有效应变和输出电压；在10 Hz工况下，传感器灵敏度由5.72 mV/t提高至8.74 mV/t，为传统直接贴片方式的1.53倍。研究结果表明，该方法能够在保持板簧结构完整性的同时有效提升板簧压电称重传感器的输出性能，可为高灵敏度车载称重传感器设计提供参考。

Abstract: To address the weak output signal and sensitivity limitation caused by the limited natural surface strain of conventional leaf-spring piezoelectric weighing sensors, this paper proposes a sensitivity-enhanced design method based on an auxetic structure. Without changing the main structure of the leaf spring or weakening its load-bearing capacity, a re-entrant hexagonal auxetic structure is attached to the high-strain region on the leaf-spring surface as a strain-amplifying component. The tensile-expansion effect of the auxetic structure is used to convert and amplify the bending deformation of the leaf spring into effective strain in the piezoelectric film. First, a half leaf-spring finite element model is established to analyze the strain distribution of the leaf spring under dynamic loading and determine the preferred placement of the piezoelectric film. Then, the geometric parameters of the auxetic structure are analyzed, and a coupled leaf spring-auxetic structure-piezoelectric film model is developed to investigate the strain amplification effect and voltage output characteristics. The simulation results show that, within the load range of 0~10 t and frequency range of 1~10 Hz, the output voltage of the piezoelectric film maintains a good linear relationship with the load mass. Compared with the conventional direct-bonding method, the auxetic structure significantly increases the effective strain and output voltage of the piezoelectric film. Under the 10 Hz condition, the sensor sensitivity increases from 5.72 mV/t to 8.74 mV/t, which is 1.53 times that of the conventional direct-bonding method. The results indicate that the proposed method can effectively improve the output performance of the leaf-spring piezoelectric weighing sensor while maintaining the structural integrity of the leaf spring, providing a reference for the design of high-sensitivity onboard weighing sensors.