Effects of Different Cooling Methods After Demoulding on the Cornering Fatigue Resistance of the Injection-Molded Long-Glass-Fiber Reinforced Thermoplastic Composite Wheel

As an un-sprung rotary part of the vehicle, the wheel has a significant effect on reducing fuel consumption and emission for conventional fuel vehicles and increasing the mileage of electric vehicles, which is significantly higher than that of a spring-loaded non-rotating part. The high-performance long fiber reinforced thermoplastic composite is used to manufacture wheel through the injection molding, which not only can achieve wheel weight reduction but also provides a new way to promote wheel lightweight due to its advantages of fast molding, easy to achieve mass production, easy to recycle materials and so on. The wheel is a key safety component of a vehicle, and its performance is one of the most important factors that affect the safety of the vehicle. Therefore, the wheel made of long fiber reinforced thermoplastic composite must meet the requirements of cornering fatigue test, radial fatigue test and 13º bench impact test. In this paper, aiming at the cornering fatigue property of the composite wheel, the influence of different cooling methods on this performance of the composite wheel after demoulding are studied. The injection molding of passenger car wheels (type 5.5J×15), composed of long-glass-fiber (LGF) reinforced thermoplastic composite (PA66+50 wt. % LGF), are fabricated under the same injection process conditions. The two cooling methods, water-cooling and air-cooling, are used to cool composite wheel to room temperature under atmospheric pressure respectively. The cornering fatigue test is carried out on the cooled composite wheels, and attain the variation curves of the maximum principal strain and the minimum principal strain with time in different directions at the test points of the spoke root of the composite wheel, respectively. In addition, during the process of cornering fatigue test of the composite wheel, the temperature change of the spokes is monitored in real-time with the aid of infrared thermal imager, and obtain the temperature distribution and change of the spokes under different load cycles. The effect of different cooling methods on the cornering fatigue performance of composite wheels is compared and analyzed based on the maximum number of cycles, the strain test results of spoke root and temperature distribution and change of composite wheel. The results show that after demouling, air cooling mode is more beneficial to improving the composite wheel cornering fatigue performance than water cooling mode. This rule is also applicable to composite wheels that are injection molded with composite materials provided by another manufacturer. The research results provide some guidance for the processing of the wheel made of long-glass-fiber reinforced thermoplastic composite.