Degradation at the fiber-matrix interphase and effects on long-term performance of composites

纤维基体界面的降解及其对复合材料长期性能的影响

• 批准号: 0626025
• 负责人: Chad Korach
• 金额: --
• 依托单位: SUNY at Stony Brook
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-09-01 至 2010-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0626025&HistoricalAwards=false
• 关键词: Degradation; fiber; matrix; interphase; effects

Abstract: CMS-0626025 Long-term degradation of composites is important for the reliability and improvement of composite material life-times. In this proposal, mechanical performance of composites is assessed with respect to quantitative measurements of nanomechanical fiber-matrix interphase properties performed as a function of degradation. Carbon-fiber reinforced composites are governed by and have been shown to fail at the interface between the fiber-reinforcements and the matrix material. The region is characteristically called the interphase between the fiber and the matrix and contains unique micromechanical properties that have demonstrated effects on bulk composite properties. The ability to quantitatively measure the interphase properties is critical to the long-term performance of composite materials, but due to the typical length-scale of the interphase being on the order of micrometers, the quantitative measurement of the interphase mechanical properties of various composites has been difficult. The use of instrumented-indentation techniques to probe mechanical properties, which have been proven viable on coating materials with sub-micrometer thicknesses, does not garner the lateral spatial resolution necessary for quantitative interphase measurements. To achieve the lateral resolution necessary, Atomic Force Microscopy (AFM) has been utilized to measure quantitative and assess qualitative mechanical properties of the fiber-matrix interphase (namely stiffness), though quantitative AFM-based techniques so far used (i.e. nanoindentation) rely on discrete point analysis of the surface and cannot provide continuous stiffness mapping. The use of Atomic Force Acoustic Microscopy (AFAM) has gained attention in the past few years as a viable method for quantitative mechanical property measurement using AFM technology. The technique involves ultrasonic acoustic transduction of the sample and measurement of the sample-AFM tip contact stiffness by means of the AFM cantilever vibrations. Nevertheless, the use of any AFM-based techniques has not been employed to study the composite fiber-matrix interphase mechanical properties as a function of degradation to achieve resolution on the sub-micrometer scale. This will be accomplished here quantitatively by using AFAM. In addition, the fracture toughness of the interphase region is of interest to bulk composite properties since it is related to cracking that occurs along the fiber-matrix interface. Measurement using normal instrumented-indentation has been attempted, but does not provide the lateral resolution necessary for adequate analysis of the interphase region only. In this work, the fracture toughness will be measured as a function of degradation utilizing a novel instrumented-scratch testing technique that has resolution on the order of the interphase length. The micromechanical properties of stiffness and fracture toughness will be used in existing micromechanical models for bulk composite mechanical properties and compared with existing data as a function of degradation.

翻译后摘要：CMS-0626025复合材料的长期退化是重要的可靠性和改善复合材料的寿命。在这个建议中，复合材料的机械性能进行评估相对于作为降解的函数进行的纳米机械纤维-基体界面性能的定量测量。碳纤维增强复合材料受纤维增强材料和基体材料之间的界面控制，并已被证明在界面处失效。该区域被称为纤维和基体之间的界面，并包含独特的微观力学性能，已被证明对散装复合材料性能的影响。定量测量界面性质的能力对于复合材料的长期性能是至关重要的，但是由于界面的典型长度尺度为微米量级，各种复合材料的界面机械性质的定量测量一直是困难的。使用仪器压痕技术探测机械性能，这已被证明是可行的涂层材料与亚微米的厚度，不获得必要的定量相间测量的横向空间分辨率。为了实现必要的横向分辨率，原子力显微镜（AFM）已被用来测量定量和评估定性的纤维基质界面相的机械性能（即刚度），虽然定量AFM为基础的技术，迄今为止使用（即纳米压痕）依赖于离散点分析的表面，不能提供连续的刚度映射。在过去的几年中，原子力声学显微镜（AFAM）作为一种利用AFM技术进行定量力学性能测量的可行方法得到了关注。该技术涉及超声波换能器的样品和样品的AFM针尖接触刚度的AFM悬臂振动的装置测量。然而，使用任何AFM为基础的技术还没有被用来研究复合材料的纤维基体界面的机械性能作为一个功能的降解，以实现在亚微米尺度上的分辨率。这里将通过使用AFAM定量地实现这一点。此外，界面区域的断裂韧性对块体复合材料性能是有意义的，因为它与沿着纤维-基体界面发生的开裂有关。已经尝试使用正常的仪器压痕测量，但不能提供仅对相间区域进行充分分析所需的横向分辨率。在这项工作中，断裂韧性将被测量为一个功能的退化，利用一种新的仪器划痕测试技术，具有分辨率的顺序的相间长度。刚度和断裂韧性的微观力学性能将用于现有的微观力学模型的散装复合材料的机械性能和现有的数据作为退化的函数进行比较。