Mechanical and electrical properties of MWCNT/PP films and structural health monitoring of GF/PP joints
Mechanical and electrical properties of MWCNT/PP films and structural health monitoring of GF/PP joints
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发表时间：
2022-04
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通讯作者：
Wencai Li;G. Palardy
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作者：
Wencai Li;G. Palardy
热塑性复合材料（TPC）的焊接是一种很有前途的无铆钉减重方法，但要在工业上广泛应用，必须对接头的结构完整性和失效预测有更高的置信度。在这项工作中，我们提出了一个创新的研究与多壁碳纳米管（MWCNTs）和嵌入巴克纸膜超声焊接TPC接头的损伤检测。多壁碳纳米管显示的结构健康监测（SHM）的复合材料接头，通过粘合剂粘接或熔融粘接组装，通过电阻变化的承诺。本研究的重点是调查多功能薄膜及其适用于超声焊接（USW）的TPC，使用两种方法：1）多壁碳纳米管填充聚丙烯（PP）纳米复合材料制备通过溶剂分散，和2）高导电性MWCNT巴克纸嵌入之间的PP薄膜热压。使用溶剂分散法合成含有5wt%和10wt% MWCNTs的纳米复合材料制剂，然后通过压缩成型来制造膜。利用Sourcemeter和Dynamic Mechanical Analyzer研究了MWCNT浓度对多功能薄膜电学和动态力学性能的影响，并在前人研究的基础上对5 - 20 wt% MWCNT/PP薄膜进行了比较。采用巴克纸和多壁碳纳米管/聚丙烯（MWCNT/PP）薄膜对玻璃纤维/聚丙烯（GF/PP）复合材料进行了单搭接剪切超声焊接。此外，电阻测量进行了弯曲载荷下的接头。据观察，15重量%和20重量%的MWCNT/PP膜具有更高的稳定性和灵敏度的电阻响应比嵌入巴克纸和低MWCNT含量的膜，证明其适用于USW和潜在的SHM。
While welding of thermoplastic composites (TPCs) is a promising rivetless method to reduce weight, higher confidence in joints ’ structural integrity and failure prediction must be achieved for widespread use in industry. In this work, we present an innovative study on damage detection for ultrasonically welded TPC joints with multi-walled carbon nanotubes (MWCNTs) and embedded buckypaper films. MWCNTs show promise for structural health monitoring (SHM) of composite joints, assembled by adhesive bonding or fusion bonding, through electrical resistance changes. This study focuses on investigating multifunctional films and their suitability for ultrasonic welding (USW) of TPCs, using two approaches: 1) MWCNT-filled polypropylene (PP) nanocomposites prepared via solvent dispersion, and 2) high conductivity MWCNT buckypaper embedded between PP films by hot pressing. Nanocomposite formulations containing 5 wt% and 10 wt% MWCNTs were synthesized using solvent dispersion method, followed by compression molding to manufacture films. The effect of MWCNT concentration on electrical and dynamic mechanical behavior of multifunctional films was examined with a Sourcemeter and Dynamic Mechanical Analyzer, and a comparison was made between 5 - 20 wt% MWCNT/PP films based on previous research. Glass fiber/polypropylene (GF/PP) composite joints were ultrasonically welded in a single lap shear configuration using buckypaper and MWCNT/PP films. Furthermore, electrical resistance measurements were carried out for joints under bending loads. It was observed that 15 wt% and 20 wt% MWCNT/PP films had higher stability and sensitivity for resistance response than embedded buckypaper and films with low MWCNT contents, demonstrating their suitability for USW and potential for SHM.