A nonlinear rheological model of castor pressing based on stress-relaxation tests
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摘要:目的
揭示蓖麻籽压榨过程中的流变特征.
方法利用单轴压榨试验装置进行应力松弛试验，获取了松弛过程中应力与时间关系.基于试验结果和半理论半经验法，利用改进的广义Maxwell模型建立了蓖麻籽压榨非线性流变模型，使用非线性回归法分段对模型参数进行求解，并将模型计算值与试验结果对比.
结果和结论综合对比结果可知：模型模拟值与应力松弛试验结果吻合较好，该模型能较好的模拟压榨应变大于0.65时蓖麻籽的非线性流变特性.
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关键词:
- 蓖麻籽 /
- 应力松弛 /
- 改进的广义Maxwell模型 /
- 非线性流变模型
Abstract:ObjectiveTo reveal rheological characteristics in the process of castor seed press.
MethodThe stress-time relationship of stress-relaxation process was obtained by stress-relaxation tests with the uniaxial compression equipment. Based on the results and the semi-theoretical and semi-empirical method, a nonlinear rheological model was established using the improved generalized Maxwell model. The parameters of the model were achieved by nonlinear regression method.The calculated values of model were compared with the experimental results.
Result and conclusionThe results show that the model calculated values matching well with the experimental results, which means the model can simulate nonlinear rheological properties of castor seeds when the strain is over 0.65.
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图 5 三元件广义Maxwell模型
Ei：弹性模量；η1：粘性系数.
Figure 5. Generalized Maxwell model of three elements
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图 10 松弛试验与非线性理论模型对比
Figure 10. The comparison of stress-relaxation value and nonlinear model
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