纸浆模塑材料在不同加载条件下的力学特性

Mechanical Properties of Molded Pulp under Various Loading Conditions

实验测量了纸浆模塑材料在不同加载条件下拉伸时的强度极限、弹性模量和泊松比等力学性能,同时给出了纸浆模塑材料的应力-应变曲线,为纸浆模塑缓冲包装结构的有限元分析和设计提供了基础数据。实验结果表明:当加载速率提高时,试件强度极限和弹性模量随之增加;当温度升高时,纸浆模塑材料的强度极限和弹性模量随之逐渐升高;当湿度升高时,纸浆模塑的强度极限和弹性模量随之降低。纸浆模塑材料单向拉伸时横向变形很小,且对温、湿度等环境因素影响敏感,泊松比的测量比较困难。数字图像相关测量方法具有灵敏度高、非接触、直接测量物体表面全场变形的特点,采用该测量方法解决了材料泊松比的测量问题。实验测得纸浆模塑材料泊松比为0.097。

Mechanical properties like ultimate stress, Young＇s modulus, and Poisson＇s ratio of molded pulp were determined under a variety of temperatures, humidity, and loading velocities. The tensile tress - strain curves under different loading conditions were plotted. Results indicated that the ultimate stress and Youngb modulus increase obviously by raising the loading velocity, whereas they both increase as temperature arises or decrease as humidity increases. These results were very useful for the FEM （finite element method ） analysis and product design of molded pulp packaging. Due to the fact that the transverse deformation of molded pulp samples is quite small and highly sensitive to temperature and humidity, it is conventionally very difficult to measure the Poisson＇s ratio. Thus the digital image correlation method （ DICM ） , with high sensitivity, oper- ated in a non-contact mode and being able to directly capture the whole surface deformation, was selected to solve the above problem. The Poissonb ratio of molded pulp investigated was determined to be 0.097.