| Glass fiber reinforced polymer(GFRP)composites are widely used in various engineering applications due to their high specific strength.At present,the heating and curing method of domestic GFRP reinforcement is mainly the traditional tunnel kiln thermal curing.In the thermal curing forming stage,the multi-section tunnel kiln connection is used to slowly heat and solidify the reinforcement.Only a small part of the heat radiated by the four quartz tubes in the tunnel kiln is projected onto the bars,which is low in efficiency and high in energy consumption.Moreover,due to the large mass of the kiln and the high heating power,the thermal inertia in the kiln is very large,and it is difficult to achieve accurate temperature.Therefore,the strength of the produced GFRP bars is unstable and relatively low.According to the relevant information,the infrared laser has good penetrability and is conducive to the precise control of the temperature of the surface of the radiated object.If we can use infrared laser to radiate heating and curing of GFRP bars,we can achieve synergistic heating inside and outside the bar,rapid temperature rise and reduced production energy consumption,and the performance and production efficiency of the bar can be greatly improved.Infrared laser heating mainly uses thermal radiation,while tunnel kiln heating mainly relies on thermal convection.In order to explore the performance difference between the two heating methods of tunnel kiln heating and infrared laser radiation heating in curing GFRP bars.We used the o-phenyl unsaturated polyester resin used in the production line of the enterprise as the matrix and the glass fiber as the reinforcing phase to prepare the glass fiber reinforced unsaturated polyester resin composite material,and produced on the production line through the infrared laser radiation heating and tunnel kiln heating two heating methods.Firstly,a series of experiments were carried out on the resin curing conditions to obtain the optimal curing temperature of the resin and the amount of curing agent,and the theoretical curing temperature and curing kinetic equation were obtained by calculating the non-isothermal curing kinetics.To ensure the accuracy of the experiment,the solidification kinetic equation establishes the parameter basis for the mathematical model in the thermal solidification simulation process.The ABAQUS finite element analysis was used to simulate the temperature field of the bars under the two heating methods,and the differences in the cross-section temperature fields of the bars under the two heating methods were obtained.Finally,through experiments and optimization of the equipment parameters on the production line of the two heating methods,the GFRP bar with the best performance was produced,and the tensile and shear performance tests were carried out on it,and the fiber at the fracture of the bar was subjected to scanning electron microscopy(SEM),infrared spectroscopy and Raman spectroscopy analysis.In summary,the experimental results show that:(1)The optimum curing agent content required for the preparation of GFRP bars with the best performance is 1.0 wt%,and the optimum curing temperature is 110°C;the characteristic temperature of the resin is determined by non-isothermal DSC method with different heating rates,and the theoretical curing temperature is finally obtained.is 108?,and the curing kinetic equation is"?(t)=1-[1-2.13×10~7exp(-7994.47/T)·t]14.25",the theoretical curing temperature calculated by the curing kinetics is almost the same as the optimal curing temperature obtained by the experiment,which confirms the reliability of the experiment.The calculation establishes the parameter basis.(2)The finite element temperature field simulation of GFRP bars with a diameter of 10mm under two heating methods shows that the radiation depth of infrared laser heating is about4 mm,and the heating radiation depth of tunnel kiln is less than 1 mm.And from the cross-section temperature distribution and curing degree distribution,it shows that the infrared laser irradiation has good internal and external temperature synergy and small temperature gradient,and the tunnel kiln heating temperature gradient is large,and the internal and external synergy is poor,which is enough to illustrate the advantages of infrared laser.(3)The tensile strength and shear strength of GFRP bars with diameters of 8 mm,10 mm,12 mm and 16 mm prepared by laser radiation heating and tunnel kiln heating have the same laws.Better and more stable mechanical properties of bars cured by laser radiation heating.The fiber at the fracture of the bar was characterized and analyzed by SEM,infrared spectroscopy and Raman spectroscopy.and the results showed that the overall fiber adhesion resin of laser cured GFRP bars was more than that of tunnel kiln cured GFRP bars.Finally,the performance improvement mechanism of the laser-cured GFRP bar was explained from the angle of the bar temperature field and interface. |
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