Cyclic fatigue testing: Assessment of polyurethane adhesive joints' durability for bus structures' aluminium assembly

Abstract

Over the years, using adhesive joints in structural applications widespread all industrial domain, achieving an amazing current usage. This is due to the benefits that this technology is capable of providing to complex-shaped structures, both in aerospace and automotive applications. Indeed, new polyurethane adhesives are a recently fastening method. This newest adhesive types bid great advantages especially on damping, impact and fatigue which are critical characteristics in the transportation industry. Besides, the current bus manufactures use this adhesive kind to join doors' structures aluminium assembly. As like, the Tunisian automotive industry ICAR uses a one-component polyurethane for doors' structure assembly. Crack problems due to fatigue are evident in those areas since they are continuously stressed. Thereby, working on more understanding polyurethane fatigue performance we investigate over this work, the response of the assembly aluminium-alloy polyurethane adhesive joints using SLJ with two design's parameters sorted from a static study under five distinct load levels. To achieve this purpose, substrates' surfaces roughness with an arithmetic average of surface heights Ra ≈ 0.6 µm, was used. Bonded specimens with 1 mm adhesive thicknesses were manufactured and examined using cyclic fatigue testing. Furthermore, the obtained results are also compared with others from literature using epoxy adhesives. Worthy results are obtained rising the effectiveness of this adhesive's type in the transport industry.

Keywords

• Single lap joint
• Polyurethane adhesive
• Surface roughness
• Aluminium alloy
• Fatigue life: Buses