非线性、粘弹性材料的特性
应力松弛指粘弹性材料在恒定应变条件下的应力释放方式。由于此类材料是粘弹性聚合物,特征属于非线性非胡克型,其中非线性表现为应力松弛和蠕变现象。
粘弹性材料兼具粘性和弹性材料的特性,通过将具有这两种特征的元件结合构建而成。 There are several models of interest to quantify the behavior. The Maxwell model predicts behavior using a spring (elastic element) in series with a dashpot (viscous element).虽然麦克斯韦模型能够很好地预测应力松弛,却很难预测蠕变。 The Voigt model places the spring and dashpot in parallel, and is the opposite of the Maxwell model in predicting the creep and stress relaxation. The Standard Linear Solid model combines the characteristics of both the Maxwell and Voigt models to display both creep and stress relaxation, and is generally accepted as the most accurate of the various viscoelastic models.
以下非材料参数均会影响聚合物的应力松弛行为:
- 初始负载量
- 加载速度
- 温度(等温与变温条件下)
- 负载介质
- 摩擦和磨损
- 紫外线或氧气侵蚀所导致的与年限相关的退化(保质期 — 长期存储)
我们的测试仪能够在各种材料(包括生物材料和工程材料)的粘弹特性评估中发挥重要作用。