Monitoring the gelation and effective chemical shrinkage of composite curing process with a novel FBG approach

Hu, Haixiao; Li, Shuxin; Wang, Jihui; Zu, Lei; Cao, Dongfeng; Zhong, Yucheng

doi:10.1016/j.compstruct.2017.04.051

Cited by 35 publications

(19 citation statements)

References 23 publications

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“…As shown in Fig.12, similar tends for the development of strain were observed. Due to the shear lag effect, the long tailed FBG sensors measured a higher shrinkage strain than the corresponding short sensors, as observed in [24].…”

Section: (3) Experimental Results and Discussionmentioning

confidence: 80%

“…A new technique referred here as tailed FBG technique has been developed in our recent work [24] to monitor the gelation during cure. Fig.8 shows the arrangement of a tailed FBG set and its work principle.…”

Section: (1) Tailed Fbg Set Monitoring Techniquementioning

confidence: 99%

“…The tailed FBG set has been used to monitor the cure process of unidirectional laminates with uniform temperature in [24]. The gelation was captured successfully and the effective transverse chemical shrinkage was determined as -0.25%.…”

Section: (1) Tailed Fbg Set Monitoring Techniquementioning

confidence: 99%

“…For most of the existing reports, physical meanings of the strain changes are not clear during cure, and the initial points of residual strain are determined unscientifically, especially the gel points. To overcome this challenge, a method based on tailed FBG sensors was proposed and utilized to monitor the gelation during uniform cure recently [24]. In this paper, tailed FBG method was extended to investigate the effect of non-uniform gelation on residual stresses in thick laminates cooperating with numerical analysis.…”

Section: Introductionmentioning

confidence: 99%

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Investigation of non-uniform gelation effects on residual stresses of thick laminates based on tailed FBG sensor

Pavier

Zhong

et al. 2018

Composite Structures

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Due to the appearance of temperature gradient and non-uniform gelation, fully understanding of residual stresses is even more complex in thick laminates. In this paper, basic mechanisms of cure process were presented firstly. Then, experimental investigation of the non-uniform gelation was carried out together with characterization of necessary material properties. Tailed FBG sets were applied to monitor the cure of thick laminates with temperature gradient. The non-uniform gelation and chemical shrinkage gradient were captured successfully. Lastly, FEM analysis integrating thermal-chemical sub-model and stress-displacement sub-model was carried out to reveal the development of residual stresses. It is demonstrated that the high temperature layer gelled earlier and showed more chemical shrinkage. The chemical strain gradient would introduce compression internal stresses in prior gelled layer and introduces tensile internal stresses in later gelled layer. For the case studied here, transverse residual stress generated by non-uniform chemical shrinkage is small. The strategy used here is promising to estimate the residual stresses for more complex cases further.

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Section: (3) Experimental Results and Discussionmentioning

confidence: 80%

Section: (1) Tailed Fbg Set Monitoring Techniquementioning

confidence: 99%

Section: (1) Tailed Fbg Set Monitoring Techniquementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Investigation of non-uniform gelation effects on residual stresses of thick laminates based on tailed FBG sensor

Pavier

Zhong

et al. 2018

Composite Structures

Self Cite

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“…[32][33][34] The gelation time can be experimentally determined using different methods such as solubility test, gel timer, dynamic thermomechanical analysis, rotational viscometer, and so forth. [35][36][37] In this study, parallel plate rheological test was used to determine the gelation time. Constant temperature rheological testing was carried out at 160, 170, 180, 190, and 200 C. The rheological curves are shown in Figure 4.…”

Section: Gelation Of Ph-ddmmentioning

confidence: 99%

Time–temperature–transformation (TTT) and TTT–viscosity diagrams of a typical benzoxazine resin

Xue

Xiao

Liu

et al. 2020

J of Applied Polymer Sci

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Benzoxazine resins have attracted much attention because of their excellent properties. As a new kind of thermosetting resin, their gelation and vitrification behaviors during the curing process are worth studying for promoting their development, but few research works have been done on this subject. In this work, an ordinary diamine-type benzoxazine resin (PH-ddm) was chosen as a research object. Its curing kinetics were studied by differential scanning calorimetry (DSC) and a phenomenological model was used to get equal curing degree curves reflecting the relationship among curing degree, curing temperature and time. Moreover, a gelation curve and a vitrification curve of PHddm based on an Arrhenius equation and a DiBenedetto equation were obtained by parallel plate rheometer and modulated DSC (MDSC), respectively. Then, a well-known time-temperature-transformation (TTT) diagram was plotted. Besides, the rheological behavior of PH-ddm was analyzed through rotatory viscometer testing and modified double Arrhenius equation to obtain the equal viscosity curves. A TTT-viscosity diagram was obtained through combining the equal viscosity curves with the TTT diagram. This is the first time for using the TTT diagram to investigate the curing process of benzoxazine resins. Our results provide an effective method to optimizing molding conditions of the benzoxazine resins.

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Residual stress in fiber reinforced thermosetting composites: A review of measurement techniques

2021

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Residual stress is inherent in any fiber reinforced composite, created by the laminates processing route and high levels of anisotropy. The aim of this article is to provide an up to date review of the current state of the art in experimental techniques for the determination of residual stress in thermosetting fiber reinforced composites. Residual stress is considered at a micro-mechanical, macro-mechanical, and global scale as each require specific techniques to investigate and offer their own unique challenges to the designer. Many advances have been made in the experimental determination of residual stress in fiber reinforced composites since the last comprehensive review of the topic by Shokrieh in 2014. However, more work still needs to be done to develop a method that is applicable to all cases and can be applied as a universal standard. It remains a significant challenge to experimentally determine residual stress in thermosetting composites.

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Monitoring the gelation and effective chemical shrinkage of composite curing process with a novel FBG approach

Cited by 35 publications

References 23 publications

Investigation of non-uniform gelation effects on residual stresses of thick laminates based on tailed FBG sensor

Investigation of non-uniform gelation effects on residual stresses of thick laminates based on tailed FBG sensor

Time–temperature–transformation (TTT) and TTT–viscosity diagrams of a typical benzoxazine resin

Residual stress in fiber reinforced thermosetting composites: A review of measurement techniques

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