Laser irradiation is a rapid, efficient, non-contact, and high-precision method that has been widely used in carbon-fiber composite processing. Using laser technology to heat carbon-fiber composites is crucial for improving productivity. To enhance the precision, quality, and industrial applicability of carbon-fiber composite processing while minimizing damage, a laser-processing technology that can achieve larger processing areas and higher processing quality must be developed. Array-laser irradiation technology is an effective approach for curing carbon-fiber composites rapidly and efficiently. The temperature-field uniformity in the irradiation region is an important factor affecting the quality of the components and thus must be analyzed quantitatively. Based on the principle of array-laser irradiation, this study establishes a finite-element temperature-field analysis model for carbon-fiber composites, which is then verified based on experiment. Additionally, the effects of spot spacing, spot size, and laser power on the temperature field of the material are evaluated based on the uniformity index and the maximum temperature difference. These results serve as an important reference for optimizing laser-processing parameters and improving the heating uniformity and efficiency of materials.

The material used in this study is an orthogonal woven laminate of CF/PPS, which is modeled as a macroscopic equivalent homogenized model to simplify the calculations. The geometrical and thermodynamic properties of the material are modeled using the COMSOL simulation software. A 980 nm continuous semiconductor laser is used to irradiate the material, obtain the overall warming pattern of the material target plate, calculate the overall temperature-rise effect on the material plate after the laser arrives at the target, and calculate the temperature-field distribution on the surface of the laminate when it is irradiated by the laser. An array-laser irradiation control system is constructed to regulate and control the laser power by processing the acquired temperature signal. Infrared thermometers and thermal cameras are used to establish an infrared temperature-measurement system as well as to accurately measure the heating-area temperature. The temperature differences between points in the horizontal direction under different parameter conditions are investigated using the control variable method, whereas the temperature-field distribution is quantitatively analyzed based on the uniformity index and the maximum temperature difference. The experimental results verify the accuracy and reliability of the simulation model.

Based on a comparison of simulated and experimental results of temperature-field maps under different conditions, the temperature-field-distribution laws of the array-laser-irradiated carbon-fiber composite laminates are consistent with each other, which verifies the accuracy of the simulation model. Comparing and analyzing the temperature difference between the points in the horizontal direction under different parameter conditions, the experimental results deviate by approximately 10% from the simulation results, which proves that the finite-element model established in this study can accurately characterize the temperature change of the material during irradiation. In this study, the uniformity of the temperature-field distribution is evaluated based on the uniformity index and the maximum temperature difference, and the effects of different parameter conditions on the uniformity of the temperature field are investigated. As the laser-spot center spacing increases from 45 mm to 55 mm with a fixed side length of 50 mm for each laser spot, the heat-affected zone increases gradually, whereas the uniformity index first increases and then decreases. When the laser-spot center spacing and the laser-spot side length are equal, the uniformity index is the highest (i.e., 0.95), whereas the maximum temperature difference is only 23.47 ℃ (Fig. 4). When the laser-spot edge length is increased from 40 mm to 60 mm, the heat-affected zone increases gradually, the uniformity index increases from 0.92 to 0.98, and the maximum temperature difference decreases from 29.89 ℃ to 11.86 ℃ (Fig. 8). When the laser power is increased from 50 W to 250 W, the area of the heat-affected zone remains almost unchanged, the uniformity index decreases from 0.97 to 0.93, and the maximum temperature difference increases from 12.83 ℃ to 37.75 ℃ (Fig. 12).

In this study, the theoretical and experimental results of a material temperature field are calculated and compared, demonstrating a consistency between the two sets of results. The uniformity index and maximum temperature difference are used as evaluation indices to assess the uniformity of the temperature field of an array-laser-irradiated carbon fiber reinforced polymer (CFRP), and the effects of spot center spacing, spot size, and laser power on the temperature-field uniformity are investigated. The results show that when the spot center spacing is equal to the side length of the spot, the uniformity index reaches the maximum value of 0.95, whereas the maximum temperature difference is only 23.47 ℃, which corresponds to the best temperature-field uniformity achieved at this time. As the spot size increases, the uniformity index increases, the maximum temperature difference decreases, and the temperature-field uniformity improves; meanwhile, as the laser power increases, the uniformity index decreases and the maximum temperature difference increases, thus resulting in a gradual decrease in the temperature-field uniformity. In addition, these three influencing factors affect the average heating rate of CFRP, among which laser power exerts the most significant effect. This study provides an important reference for optimizing laser-processing parameters and improving material heating uniformity and efficiency.