Effects of Loading History on Mechanical Performance of Semi-crystalline Polymers and Their Composites

加载历史对半晶聚合物及其复合材料力学性能的影响

• 批准号: RGPIN-2015-06767
• 负责人: Jar, PeanYue
• 金额: $ 1.6万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=614353
• 关键词: Effects; Loading; History; Mechanical; Performance

The proposed program is concerned about the influence of loading history on the change in mechanical properties for semi-crystalline polymers (SCP) and their glass-filled composites. Motivation for the program comes from the discovery of changes in mechanical properties owing to the loading conditions that are actually acceptable by plastic pipe industry for repair or regular maintenance. Three projects are proposed, of which the overall objective is to develop knowledge and technology to assess the possibility of crack initiation and growth in SCP and SCP composites that are intended for long-term, load-carrying applications.      Two SCPs and their glass-filled composites, based on polyethylene (PE) and poly(ether-ether-ketone) (PEEK), will be selected for the study. The research will be carried out using two approaches. One is through experimental testing to evaluate the influence of loading histories on the mechanical properties, and the other through finite element (FE) simulation to establish the constitutive equations and critical stress and strain states for crack initiation and growth. Concepts from the damage mechanics will be used to identify parameters that can be used to represent the variation in the stress and strain state, such as disintegration of the ordered structures in SCP or presence of micro-cracks at the glass-matrix interface, and to establish the relationship between damage evolution and changes in mechanical properties.      Two of the three projects are about the pure SCPs and the other their glass composites. The projects on pure SCPs are to explore the possibility of using accumulation of deformation, instead of change in temperature and strain rate, to generate the unusual ductile-brittle (uDB) transition that is known to lead to slow crack growth (SCG) in plastic pipes. These two projects are to understand the role of loading history on the change in mechanical properties, and to develop a non-destructive evaluation (NDE) technique for monitoring the stress and strain state in order to prevent catastrophic failure due to the SCG development. All possible loading modes, i.e. tension, compression, shear and their combinations, will be investigated, to identify the critical loading conditions to initiate the uDB transition. The project on SCP composites, on the other hand, is to search for the possibility of characterizing the crack coalescence and growth from micro-cracks at the fibre-matrix interface, and to establish the influence of the presence of micro-cracks on the overall mechanical properties.      The three projects will provide training to 3 doctoral students in the next 5 years. When opportunities arise, undergraduate (UG) students will be recruited during the summer, to conduct small-scaled projects that are complementary to the proposed study and are suitable for the UG students’ background.

所提出的计划是关注的加载历史的影响，在力学性能的变化，半结晶聚合物（SCP）和他们的玻璃填充复合材料。该计划的动机来自于发现由于塑料管道行业实际上可接受的修复或定期维护的负载条件而导致的机械性能变化。提出了三个项目，其总体目标是开发知识和技术，以评估用于长期承载应用的SCP和SCP复合材料中裂纹萌生和增长的可能性。      两个SCP及其玻璃填充复合材料，基于聚乙烯（PE）和聚（醚醚酮）（PEEK），将被选择用于研究。研究将采用两种方法进行。一种是通过实验测试来评估加载历史对力学性能的影响，另一种是通过有限元（FE）模拟来建立裂纹萌生和扩展的本构方程和临界应力和应变状态。从损伤力学的概念将被用来识别参数，可用于代表应力和应变状态的变化，如SCP中的有序结构的解体或在玻璃基质界面处的微裂纹的存在，并建立损伤演化和机械性能的变化之间的关系。      这三个项目中有两个是关于纯SCP的，另一个是关于它们的玻璃复合材料的。纯SCP的项目是探索使用变形的累积而不是温度和应变速率的变化来产生不寻常的延性-脆性（uDB）转变的可能性，这种转变已知会导致塑料管道中的缓慢裂纹扩展（SCG）。这两个项目是为了了解加载历史对机械性能变化的作用，并开发一种用于监测应力和应变状态的非破坏性评估（NDE）技术，以防止由于SCG开发而导致的灾难性故障。将研究所有可能的加载模式，即拉伸、压缩、剪切及其组合，以确定启动uDB过渡的临界加载条件。另一方面，SCP复合材料的项目是寻找表征纤维-基体界面处微裂纹的裂纹合并和生长的可能性，并确定微裂纹的存在对整体机械性能的影响。      这三个项目将在未来5年内培养3名博士生。当机会出现时，本科（UG）学生将在夏季招募，进行小型项目，这些项目是对拟议研究的补充，并适合UG学生的背景。