The self-resistance electrical (SRE) heating method to cure the carbon-fiber-reinforced polymer (CFRP) parts possesses the advantages of rapid and volumetric heating, low energy consumption, and low asset investment. But the current SRE heating methods are difficult to uniformly cure the shaped CFRP parts due to the non-uniformly distributed Joule heat power in the parts with a varying cross-sectional area. In this paper, an optimized multi-zone SRE heating method is proposed, in which the uniform heating and curing process of the shaped CFRP part is firstly achieved. By optimizing the orientation of the rectangular zones, the local overheating caused by the voltage gradient and current diffusion between different zones is notably suppressed. Combined with the electro-thermal numerical analysis, the influence of the positional offset of electrodes in two adjacent zones on the temperature uniformity is investigated. Based on this, an automated zone discretization algorithm and the optimal selection method of the zone orientation are established. The proposed method is numerically and experimentally validated with the typical-shaped CFRP parts, and the results are compared with that of the existing SRE heating method. The proposed method realizes that the maximum in-plane temperature difference of shaped CFRP parts is reduced by more than 80%. This method significantly improves the temperature uniformity of shaped CFRP parts during the multi-zone SRE heating process, which provides a potential solution for high-quality and efficient curing of CFRP parts. 

https://www.researchsquare.com/article/rs-1205750/latest.pdf

Self-resistance electric heating of shaped CFRP laminates: temperature distribution optimization and validation

Curing process is usually a key step in the molding process of polymer-matrix composites (PMCs). Traditional oven (autoclave) heating curing (OHC) methods have many challenges such as long curing cycles, high energy consumption and high costs. Electrical resistance heating curing (ERHC) method enables targeted heating of specific areas, which has the potential to achieve uniform curing and minimize the overall energy demand. Therefore, ERHC method has important application value for the preparation of low energy consumption and high- quality PMC. In this review, we first briefly introduce the heating mechanism of ERHC. Then, according to the different forms of electric heating elements used for ERHC, the ERHC method is divided into three types: fibers, fillers and membrane sheets. Subsequently, the preparation methods of three types electric heating elements are summarized. Finally, the advantages of ERHC are obtained through analysis and comparison. 

Realizing the curing of polymer composite materials by using electrical resistance heating: A review

Carbon fiber-reinforced thermoplastic (CFRT) composites have been dramatically employed in the automotive field on account of their superior performances, such as being light weight and high-strength. Self-resistance electric (SRE) heating provides a solution to the problem of high energy consumption in the conventional process of CFRT composites. The effect of SRE heating on the surface chemical properties of carbon fiber (CF) was investigated by X-ray photoelectron spectroscopy (XPS). XPS analysis suggests that the C-O-C epoxy group, the CF surface, would be degraded after SRE heating with strong current intensity, while there are weak changes in the content of -C-OH, -C-O-C-, -C-NH2 and -COOH groups with current intensity. The interfacial bonding properties and the radial distribution function (RDF) of CF–PP interfaces were carried out by molecular dynamics (MD) simulation. The simulation results show that the adhesion between the PP and the E44 sizing agent is weaker than that between CF and PP. There are no interaction modes between the PP and E44 sizing agent except van der Waals and electrostatic adsorption. The presence of the E44 sizing agent does not change the bonding mechanism at the interface of CF/PP.

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Molecular Dynamics Simulation on the Effect of Self-Resistance Electric Heating on Carbon Fiber Surface Chemical Properties and Fiber/PP Interfacial Behavior

Characterization of Joule heating and deconsolidation behavior of continuous carbon fiber reinforced polyamide 6 composites under self-resistance electric heating

Current technologies for the manufacture of fiber-reinforced polymer composites are energy-intensive, environmentally unfriendly, and time-consuming and require expensive equipment and resources. In addition, composites typically lack key nonstructural functionalities (e.g., electrical conductivity for deicing, lightning strike protection, and structural health monitoring), which are crucial to many applications such as aerospace and wind energy. Here, we present a new approach for rapid and energy-efficient manufacturing of multifunctional composites without using traditional expensive autoclaves, ovens, or heated molds used for curing of composites. Our approach is predicated on embedding a thin conductive nanostructured paper in the composite layup to act as a resistive heater for triggering frontal polymerization of the matrix thermosetting resin of the composite laminate. Upon passing electric current, the nanostructured paper quickly heats up and initiates frontal polymerization, which then rapidly propagates through the thickness of the laminate, resulting in rapid curing of composites (within seconds to few minutes) irrespective of the size of the composite laminate. The integrated nanostructured paper remains advantageous during the service of the composite part by imparting new functionalities (e.g., deicing) to the cured composite, owing to its excellent electrical conductivity and electrothermal properties. In this work, we first study the influence of several composite processing parameters on the electrothermal properties of the nanostructured paper and determine the power required for rapid initiation of frontal polymerization. We then successfully fabricate a 10 cm × 10 cm composite panel within 1 min using only 4.49 kJ of energy, which is 4 orders of magnitude less than the energy consumed by the traditional bulk, oven-curing technique. Detailed experiments are conducted to provide an in-depth understanding of the effect of heater position, tooling material, and input power on frontal curing of composite laminates. The multifunctional response of produced composites is demonstrated by performing a deicing experiment, where a 50 × 50 × 3 mm3 cube of ice is completely melted within 3 min using an input power of 77 W.

Yingxiang Shen

Papers

Layered self‐resistance electric heating to cure thick carbon fiber reinforced epoxy laminates

Self-resistance electric heating of shaped CFRP laminates: temperature distribution optimization and validation