基于准静态压缩的果实黏弹塑性模型

Nonlinear viscoelastic plastic model of the fruits under quasi-static compressive loading

目前对果实黏弹塑性特征与模型进行表征比较困难。基于果实等速压缩变形特征,提出了一表征其黏弹塑性的流变模型。该模型包括3个非线性弹簧元件、一个黏性元件以及一个滑块元件。结合压缩应力—应变试验曲线特征与模型特性提出了模型参数的数值确定方法。采用梨果实全果肉、带核果肉两种试样进行试验,获得了其黏弹塑性模型参数。结果表明试验与理论模型结果非常吻合,果核对其黏弹塑性有较大影响。采用本模型结合试验结果能较准确简便地确定类似特性果实的流变特征参数。研究结果为果品黏弹塑性流变特性分析以及模型表征提供了一种新的方法。

It is commonly difficult to characterize the properties and model of a nonlinear viscoelastic plasticity of fruits. Based on the deformation characteristics of the fruits under constant rate quasi-static compression, a general rheological model of a nonlinear viscoelastic plastic solid was developed. The model is composed of three nonlinear springs, one viscous damper and one slide damper elements. The method for defining and determining the parameters of the model was proposed by combining the testing curves of stress versus strain with the model characteristics. The quasi-static compression testing was performed with two kinds of pear specimens of full flesh and flesh with a core. The parameters of the nonlinear viscoelastic plastic model were computed. The results show that theoretical model is well agreed with the test results, the viscoelastic plasticity of the fruit was influenced by the fruit core. The model can accurately and conveniently be used to determine the rheological parameters of pears and other fruits with similar properties.