发泡聚乙烯最大加速度-静应力曲线快速获取方法研究

Rapid Acquisition Method of Maximum Acceleration-Static Stress Curve for Foamed Polyethylene

目的研究快速、准确预测最大加速度-静应力曲线的方法。方法首先利用落锤冲击试验机获取了5个不同高度下,5种不同厚度的发泡聚乙烯的最大加速度-静应力曲线。在此基础上,分析对比文中3种不同的改进拟合法与已有的动应力与动能量多项式拟合法的区别。结果研究发现,当不区分高度的情况下,以最大加速度因子为函数值,以跌落高度、衬垫厚度、静应力为变量进行拟合时,其代表预测精度R^(2)的平均为0.835,相比动应力与动能量多项式拟合法的0.2996要高。但曲线右侧的预测精度偏低。引入以静应力为变量的多项式作为修正因子后,R^(2)的平均值为0.934。预测精度有所提高,右侧的预测偏差减小,但仍存在。在区分高度的情况下,以带有修正因子的公式进行预测时,R^(2)的平均值为0.984,曲线向右侧预测偏差逐渐增大的现象明显改善。结论区分高度情况下,利用带修正因子的预测公式可以快速且较准确地预测最大加速度-静应力曲线,可以为冲击防护设计及相关软件的开发提供一定的帮助。

The work aims to study a method that can predict the maximum acceleration-static stress curve quickly and accurately.Firstly,the maximum acceleration-static stress curves of foamed polyethylene of 5 different thickness at 5 different heights were obtained by a drop hammer impact testing machine.On this basis,the differences between the three different improved fitting methods proposed and the existing dynamic stress and dynamic energy polynomial fitting methods were analyzed and compared.It was found that when the maximum acceleration factor was used as a function value and the drop height,pad thickness,and static stress were used as variables for fitting without distinguishing heights,the average R^(2) value representing prediction accuracy was 0.835,which was much higher than the value of 0.2996 got by the polynomial fitting method of dynamic stress and dynamic energy.However,the prediction accuracy on the right side of the curve was still low.After a polynomial with static stress as the variable was used as the correction factor,the average value of R^(2) was 0.934,indicating a significant improvement in prediction accuracy.The prediction deviation on the right side was reduced,but it still existed.When a formula with a correction factor was used for prediction while heights were distinguished,the average value of R^(2) was 0.984,and the phenomenon of gradually increasing prediction deviation towards the right side of the curve was significantly improved.Under different heights,the use of prediction formulas with correction factors can quickly and accurately predict the maximum acceleration-static stress curve,which can provide certain assistance for impact protection design and related software development.