Papers by Author: Xiao Su Yi

Abstract: Optimizing the curing temperature to reducing the process costs may influence the properties of the material and bring quality assurance aspects. To solving the problem, real-time strain monitoring of the curing process has become more and more important and urgent. Fiber Bragg grating sensors were successfully used in this work to monitoring the residual strain building-up and the gelling phenomena of an RTM epoxy resin. The results shows chemical shrinkage strain during isothermal curing is bigger for higher curing temperature, but the average linear shrinkage ratio during cooling is smaller.

Abstract: Based on the “ex-situ” toughening concept, thermoplastic nylon (PA) nonwoven fabric with high porosity was chosen as the toughening layer, and the interlaminar toughened composites were fabricated via RTM process. Compression strength after impact (CAI) properties were investigated as well as the toughening mechanism. The results indicated that there is no bicontinuous phase structures formed by reaction-induced phase decomposition and inversion. The PA nonwoven fabrics still kept the original structure in composites interlaminar, and formed a macroscopical bicontinuous structure with the matrix resin, which also showed remarkable toughening effect. The CAI value increased from 212MPa to 281MPa.

Abstract: Chemical cure shrinkage of polymer matrix is a significant source of residual strain formation in composite products during curing. In this paper, fiber Bragg grating (FBG) sensors were used to monitor the free strain development caused by chemical shrinkage and compared with results of differential scanning calorimetry and rheological analysis. The results showed that the gel point could be clearly identified by FBG sensors and compressive residual strain of around 800με was caused by isothermal curing reaction after gelation. The relationship between the chemical shrinkage ratio and conversion degree was found to be nonlinear.

Abstract: This article is intended to outline a novel concept of interlaminar 3-3 connectivity of fiber-reinforced laminated composites. This microstructure is typically realized by using thorny ZnO whiskers exactly located in the interlayer of glass or carbon fabric for RTM. From the initial testing, the interlaminar shear strength (ILSS) is noted to increase up to 150% while retaining the most other in-plane properties. Mechanistic penetrating and pinning are considered to be the dominant mechanism of interlaminar toughening effect, with the evidence of the broken, fragmented and pull-out whiskers observed in the fracture morphologies.