Mechanical properties and microstructural characterization of semi-crystalline polymers and fiber composites

半结晶聚合物和纤维复合材料的机械性能和微观结构表征

• 批准号: RGPIN-2022-03588
• 负责人: Jar, PeanYue
• 金额: $ 2.33万
• 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: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=760193
• 关键词: Mechanical; properties; microstructural; characterization; semi

The proposed study is concerned about mechanical performance of semi-crystalline polymers (SCP) and fiber composites (FRP) of which the microstructure consists of two phases, i.e. amorphous and crystalline phases in SCP and fiber and polymer matrix in FRP. Interaction between the two phases is known to start at small deformation. With a strong viscous behavior and low resistance to damage development, the dominant mechanisms for deformation of SCP and FRP vary with the loading history. As a result, conventional test methods cannot provide full characterization of mechanical performance of these materials in service.    The long-term goal of the proposed study is to develop a mechanism-based concept to define mechanical properties for SCP and FRP so that the lab test results can be used to evaluate mechanical performance in the long-term service. Study in the next five years has two specific objectives. The first is to develop two new test methods, one for SCP and the other for FRP, to separate mechanical properties associated with the viscous deformation from those with the quasi-static counterpart, and to use changes of the mechanical properties to quantify their resistance to damage. The other objective is to examine microstructural changes of SCP and FRP to identify mechanisms that dominate the deformation process, and to determine the critical conditions for the mechanism changes. Dominant mechanisms in three fundamental loading modes of tension, compression and shear will be considered. By correlating the mechanical properties obtained from the new test methods with mechanisms established from the microstructural changes, the proposed study will provide a foundation for developing a mechanism-based concept to characterize mechanical properties for SCP and FRP, and to evaluate efficacy of this concept for quantifying the load-carrying performance of these materials.    The study will provide training to two PhD and two MSc students, plus one undergraduate student in each summer. Currently, one PhD student is developing a new test method for SCP, and has made significant progress in separating the viscous stress component from the quasi-static counterpart to establish the corresponding stiffness change and damage development during the test. An MSc student will be recruited to use this new test method to examine two SCPs with their amorphous phases in different states (rubbery or glassy), and to characterize their influence on the crystalline microstructure under loading. The second PhD student will develop a new test method for FRP and to characterize the void generation in the matrix and critical conditions for its evolution to cause delamination. The second MSc student will study the influence of a combined loading mode of tension and compression on the mechanical property changes for each of the two phases in SCP, to evaluate the feasibility of quantifying the damage development when subjected to a combination of different loading modes.

拟议的研究涉及半晶体聚合物（SCP）和纤维组成（FRP）的机械性能，其微结构由两个阶段组成，即SCP中的无定形和晶体阶段，在FRP中，纤维和聚合物基质组成。已知两个阶段之间的相互作用是从小变形时开始的。具有强烈的粘性行为和对损伤发展的低抵抗力，SCP和FRP变形的主要机制随载荷历史而变化。结果，传统的测试方法无法完全表征这些材料的机械性能。拟议研究的长期目标是开发基于机制的概念来定义SCP和FRP的机械性能，以便可以使用实验室测试结果来评估长期服务中的机械性能。未来五年的研究有两个具体的目标。首先是开发两种新的测试方法，一种用于SCP，另一种用于FRP，是将与粘性变形相关的机械性能与具有准静态对应物的粘性变形相关的机械性能，并使用机械性能的变化来量化其对损害的阻力。另一个目的是检查SCP和FRP的微观结构变化，以识别主导变形过程的机制，并确定机制变化的关键条件。将考虑三种基本荷载模式，压缩和剪切的主要机制。通过使用微观结构变化确定的机制纠正从新测试方法获得的机械性能，该研究将为开发基于机制的概念以表征SCP和FRP的机械性能，并评估该概念的有效性以量化这些材料的负载性能。该研究将为两名博士学位和两名MSC学生提供培训，并在每年夏天提供一名本科生。目前，一位博士生正在为SCP开发一种新的测试方法，并在将粘性应力成分与准静态对应物分开以建立相应的刚度变化和测试期间的损伤发展方面取得了重大进展。将招募一名MSC学生使用这种新的测试方法在不同状态（橡胶或玻璃状）中检查两个SCP，并表征它们对加载下晶体微结构的影响。第二博士生将开发一种针对FRP的新测试方法，并在矩阵中表征空隙的生成以及其进化的临界条件以引起分层。第二名MSC学生将研究SCP中两个阶段中每个阶段的机械性能变化的组合加载模式的影响，以评估量化损害发展的可行性，并在遭受不同载荷模式的组合时进行量化。