Detailed study on yield, damage and failure of polymers and composites - modelling mechanical behaviour

这项建议涉及对建筑行业中使用的聚合物和聚合物复合材料的行为进行测试和分析建模。它包括对短期和长期业绩和失败的研究。影响失效模式和时间的长期性能可能是安全使用聚合物作为结构材料需要解决的最关键问题。在这项拟议的研究中，将研究聚乙烯(PE)和纤维增强聚合物(FRP)复合材料。PE的行为和失效可以表现为随时间变化的应力应变响应、缓慢的裂纹扩展、蠕变断裂或屈服应力；所有这些都与其环境应力抗裂性(ESCR)直接相关。典型的测试包括拉伸蠕变或拉伸应力-应变测试；然而，在这项工作中，我们计划将其扩展到压缩和剪切测试。PE在建筑中经常被用作金属元素的支撑物(例如桥梁缆索)，因此压缩和剪切性能很重要。相同类型的PE的拉伸、压缩和剪切测试将提供独特的数据库，可用于合理的建模方法。纤维增强聚合物(FRP)复合材料在建筑行业中是一个很有前途的选择，在这些行业中，腐蚀问题需要解决，材料的轻量化很重要，或者需要电磁惰性。我们建议开发通过数学模型来预测FRP复合材料强度的方法。玻璃钢利用热固性聚合物基质(聚酯、乙烯醚)来保护和粘合纤维(玻璃、碳、芳纶)。这项研究将集中在根据聚合物基质中夹杂物和界面的数学模型来确定强度。这项建议描述了一个为期三年的研究计划，补充正在进行的研究(由帝国石油资助)在(微观结构)分子水平上研究PE的蠕变和破坏行为。这项拟议的研究项目是滑铁卢大学开展的一个更大的研究项目的一部分。

This proposal addresses testing and analytical modelling of the behaviour of polymers and polymer composites that are used in the construction industry. It includes studies on short-term and long-term performance and failure. Long-term performance, which influences failure mode and time, is likely the most critical issue that needs to be addressed in order to safely use polymers as structural materials. In this proposed research, polyethylene (PE) and fibre reinforced polymer (FRP) composites will be studied. Behaviour and failure of PE can be characterized by time-dependent stress-strain response, slow crack growth, creep rupture or yield stresses; all of which are directly related to its environmental stress crack resistance (ESCR). Typical testing involves tensile creep or tensile stress-strain testing; however, in this work we plan to extend this to compression and shear testing. PE is often utilized in construction as a support for metal elements (e.g for bridge cables) and thus compression and shear behaviour are important. Tensile, compression and shear testing of same types of PE will provide unique database that can be used for rational modelling methodologies. Development of such modelling is also part of this proposal.Fibre reinforced polymer (FRP) composites are a promising option in construction industry where the problems with corrosion need to be addressed, lightness of the material is important, or the electromagnetic inertness is required. We propose to develop methodologies for predicting strength of FRP composites through mathematical modelling. FRP utilize thermoset polymer matrices (polyester, vinylesther), which protect and bond fibres (glass, carbon, aramid). The study will concentrate on determination of strength based on mathematical model for inclusions and interfaces in the polymer matrix. This proposal describes a three-year research program, complementary to the on-going research (funded by Imperial Oil) on creep and failure behaviour of PE studied at the (microstructural) molecular level. The proposed research project is part of a larger research program carried out at the University of Waterloo.