Abstract To verify a linear relation between normalized mechanical property and moisture ratio, in-plane tensile tests were performed on four types of paperboard from different manufacturers. Tensile properties were normalized with respect to the property at standard climate (50 % RH, 23 °C). Short-span Compression Tests were also performed to investigate if the relation was linear also for in-plane compression. The tests were performed at different relative humidity (20, 50, 70 and 90 % RH) but with constant temperature (23 °C) in MD and CD, respectively. The linear relation was confirmed for the normalized mechanical properties investigated. In fact, when also the moisture ratio was normalized with the standard climate, all paperboards coincided along the same line. Therefore, each mechanical property could be expressed as a linear function of moisture ratio and two parameters. Moreover, an in-plane bilinear elastic-plastic material model was suggested, based on four parameters: strength, stiffness, yield strength and hardening modulus, where all parameters could be expressed as linear functions of moisture ratio. The model could predict the elastic-plastic behavior for any moisture content from the two parameters in the linear relations and the mechanical properties at standard climate.

中文翻译：

---

纸板机械性能随水分变化的弹塑性模型

摘要 为了验证归一化机械性能与水分比之间的线性关系，对来自不同制造商的四种纸板进行了面内拉伸试验。拉伸性能相对于标准气候（50% RH，23°C）下的性能进行归一化。还进行了短跨度压缩测试，以研究该关系对于面内压缩是否也是线性的。测试是在不同的相对湿度（20、50、70 和 90 % RH）下进行的，但分别在 MD 和 CD 保持恒定温度 (23 °C)。对于所研究的归一化机械性能，确认了线性关系。事实上，当水分比率也用标准气候标准化时，所有纸板都沿着同一条线重合。所以，每个机械性能都可以表示为水分比和两个参数的线性函数。此外，提出了基于四个参数的面内双线性弹塑性材料模型：强度、刚度、屈服强度和硬化模量，其中所有参数都可以表示为水分比的线性函数。该模型可以根据线性关系中的两个参数和标准气候下的机械性能预测任何水分含量的弹塑性行为。