The aim of this study is the evaluation of fatigue strength of glass-fibre-reinforced polypropylene composite (PPGF35) by applying both the Risitano Thermographic Method (RTM) and the new static Thermographic Method (STM). Fifteen tensile tests and twenty cyclic tests were carried out to evaluate the fatigue strength of PPGF35 by applying traditional and innovative energy methods. The results show how the energy methods used are very useful for rapid identification of the material’s fatigue strength, saving companies time and money.