Strength evaluation of polyurethane elastomeric bonded joints under extreme service conditions

This paper presents an experimental study on the extreme durability of polyurethane (PU) elastomeric bonded joints during service. The service life of bonded joints is affected by environmental aging, service temperature and the state of the forces applied. Therefore, the extreme mechanical properties of the bonded joints were confirmed at aging time (0, 20, …, 120 cycles), service temperature (−40 °C, −20 °C, …, 80 °C) and loading angle (0°, 15°, …, 90°), and the failure modes were analyzed under the corresponding test conditions. In addition, Fourier transform infrared (FTIR) was not only used to explain the aging behavior of the PU adhesive, but also established a method for predicting the strength of bonded joints. The results show that the extreme service conditions of the bonded joints are 120 aging cycles, 80 °C service temperature and 90° loading angle, when the residual strength of the joints is the lowest. Moreover, the joint failure modes show inconsistent aging patterns under different experimental conditions. The proposed FTIR-based joint strength prediction method establishes an intrinsic link between the joint strength and the absorbance intensities of functional groups, which is more accurate in predicting the mechanical properties of bonded joints after aging.