Investigation of the fatigue behavior of thermoplastic composites by load increase tests

Fatigue is one major load case in many structures for transport applications. New materials often lack the necessary data base for a fast application in cyclic loaded components due to time consuming testing series. The aim of this study is the evaluation of the load increase test as method to determine a possible fatigue limit of glass fiber reinforced polyamide 6. Under the working hypothesis that cracks are the main contributors for heat emission, the results show that the investigated material exhibits a different behavior in comparison to thermosets. Instead of crack formation experimental and numerical data indicate that the matrix relaxes under fatigue loading. This relaxation could potentially lead to crack prevention but might also result in the observed sudden failure behavior of the material. These findings suggest a totally different behavior of thermoplastic composites under fatigue loading.

Automated summary

The study evaluates the load increase test as a method to determine the fatigue limit of glass fiber reinforced polyamide 6 and finds that the material exhibits a different behavior compared to thermosets under fatigue loading. Instead of crack formation, the matrix relaxes, potentially leading to crack prevention but also sudden failure behavior. This suggests a distinct behavior of thermoplastic composites under fatigue loading.