Abstract
Fiber-reinforced polymer (FRP) materials are increasingly used in automotive industrial fields to achieve lightweight. In order to study the influence of high temperature and high humidity on the bonding structure between different materials, this paper selects basalt fiber-reinforced resin composite materials (BFRP) and aluminum alloy (Al), and uses Araldite® 2012 and Araldite® 2014, two adhesives, to make single lap joints (SLJs). The aging test was carried out for 0 (unaged), 10, 20, and 30 days under the environment of 80 °C/95% relative humidity (RH) and 80 °C/pure water. In this work, simple Fickian law was used to simulate the hygroscopic change law of dumbbell specimens of two adhesives and BFRP in a pure water environment. It was discovered that Araldite® 2012 is most affected by moisture, but the time to reach the maximum water absorption in Araldite® 2014 was shorter than in Araldite® 2012. The failure strength of the joint was obtained through a quasi-static tensile experiment, and it was found that the Araldite® 2014 adhesive joint first increased and then decreased in a high temperature environment. The strength increased by 11.63% after 20 days of aging under an 80 °C/95%RH environment, and increased by 16.66% after 10 days of aging under an 80 °C/pure water environment, which indicates that post-curing reaction occurred. The strength of Araldite® 2012 joints showed a downward trend. After 30 days of aging, it reduced by 40.38% under an 80 °C/95%RH environment and 41.11% under an 80 °C/pure water environment. By observing the load-displacement curve, it was found that, as time increased, the slope of the curve decreased, indicating that the stiffness of the bonded joint decreased with time. The failure modes of the joints were analyzed by macroscopic images and microscopic SEM methods, and the results showed that the surface failure transitions from a mixed failure to a complete tear failure over time. The failure of the basalt fiber/resin interface was because the interaction between the epoxy resin in the adhesive and the epoxy resin in BFRP was greater than the force between the basalt fiber layer and the epoxy resin layer in the BFRP sheet.
Highlights
Compared with carbon fiber-reinforced resin (CFRP) composite materials, basalt fiber-reinforced resin composite materials (BFRP) composite materials have the advantages of a wide range of raw materials and low cost
The thickness of the BFRP composite sheet was 2 mm, and it was made of twill, unidirectional prepreg, BFRP was bought from Zhongdao Technology Co., Ltd. (Jilin, China)
Based on the above analysis, the following conclusions can be drawn: Araldite® 2012 was most affected by moisture, but the time for Araldite® 2014 to reach the maximum water absorption was shorter than that for Araldite® 2012, and the least affected by moisture was BFRP
Summary
Ke Lu et al [9] studied the bond strength degradation mechanism of two bonded joints at high temperatures. Dry and wet, the effect of the water absorption rate of fabric, flax, and jute fiber-reinforced bio-resin matrix composites on the elastic modulus and strength was Polymers 2021, 13, 2593 studied. This article is devoted to studying the influence of temperature and humidity coupling on the mechanical properties of BFRP-Al bonded joints. The dumbbell-shaped specimens and the BFRP substrates were tested for water absorption, and the water absorption conditions of the materials were studied to provide help for the analysis of the failure mechanism of the bonded joint
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