Facing increasingly serious resource crises, energy conservation is becoming the development trend of various delivery vehicles, and lightweight is an important way to achieve energy conservation. In this paper, the basalt fiber-reinforced resin composite material (BFRP) was selected to study the effect of its bonding structure, and it was used to make BFRP-BFRP joints. Two adhesives, Araldite^®2012 and Araldite^®2015, were used to make single-lap joints and dumbbell-shaped specimens. Aging environments of 80 °C/95% RH and 80 °C/pure water were used for the 0-day (unageing), 10-day, 20-day, and 30-day aging tests, respectively. According to Fick’s second law, the moisture absorption change model of two adhesives was established, and it was found that the water absorption process could be divided into two stages, which explains the precipitation of water molecules and the reaction of water molecules with functional groups. The maximum average failure load and load-displacement curves under different environments and different joints were obtained by using the electronic universal tensile machine, and the exposure time was more important than the effect of humidity. At the same time, the change law of failure strength and ductility were analyzed. The change of T_g (Glass transition temperature) was analyzed by differential scanning calorimetry (DSC) equipment, and the results showed that molecular chain rupture was the reason for the decrease of T_g. It could be seen from the joint failure mode distribution that Araldite^®2012 adhesive was easily affected by the environment, and the joint of Araldite^®2015 adhesive was affected by the combined effect of the adhesive and BFRP.

In this paper, a heat-flow coupling model of laser welding at preheating temperature was established by the FLUENT 19.0 software. The fluctuation of the keyhole wall and melt flow behavior in the molten pool under different preheating temperatures were analyzed, and the correlation between keyhole wall fluctuation and molten pool flow with spatters and bubbles was obtained. The results indicate that when the outer wall in the middle of the rear keyhole wall is convex, the inner wall is concave, which causes spatter or the bottom of the keyhole to collapse. When the metal layer in the middle of the rear keyhole wall turns into obliquely upward flow, welding spatter is generated. In contrast, the metal layer in the middle of the rear keyhole wall changes to flow into the keyhole, and the bottom of the keyhole collapses. When the preheating temperature is 300 K (ambient temperature), 400 K, and 500 K, the inner wall in the middle of the rear keyhole wall is concave. With the increase in the preheating temperature, the area of the concave gradually increases, and the size of the liquid column behind the keyhole opening gradually decreases. When the preheating temperature is 300 K, there are more spatters above the molten pool. In comparison, when the preheating temperature is 400 K or 500 K, there are less spatters, and the bottom of the keyhole collapses.

Our aim was to study the influence of the surface treatment process on the mechanical properties of an adhesive. This study takes aluminum alloy 6061 as the substrate; carries out grinding, sandblasting, plasma, grinding + plasma, and sandblasting + plasma surface treatment processes; and chooses the ISR 7008 adhesive to make aluminum alloy butt joints, and the joints Connectors are in −40 °C, −20 °C, 0 °C, 40 °C, 60 °C, and 80 °C environments, respectively (1–3 days of a constant-temperature test). The results show that the plasma surface treatment process helps to improve the activity and hydrophilicity of the bonding surface; the plasma surface treatment process helps to improve the adhesive strength of the joints under the environment of −40 °C and 80 °C; and under the environment of −20–60 °C, the sandblasting + plasma surface treatment process helps to improve the adhesive strength of the joints. By analyzing the infrared spectra of the ISR 7008 adhesive, it was found that the contents of ${\gamma }_{\mathrm{N}-\mathrm{H}}$, ${\nu }_{\mathrm{C}-\mathrm{C}}$, ${\nu }_{\mathrm{C}-\mathrm{N}}$, and ${\nu }_{\mathrm{C}-\mathrm{O}}$ were higher in the interval from 25 °C to 80 °C than those in the interval from −40 °C to 0 °C, which resulted in the decrease in adhesive properties.

The effects of droplets filling the molten pools during the double-sided laser beam welding (DSLBW) of T-joints was established. The dynamic behavior of the keyhole and the molten pool under different droplet filling modes were analyzed. The results indicated that compared with the contact transition, the stability of metal flow on the keyhole wall was reduced by free transition and slight contact transition. At the later stage of the droplet entering the molten pool via free transition, slight contact transition, and contact transition, the maximum flow velocity of the keyhole wall was 5.33 m/s, 4.57 m/s, and 2.99 m/s, respectively. When the filling mode was free transition or slight contact transition, the keyhole collapsed at the later stage of the droplet entering the molten pool. However, when the filling mode was contact transition, the middle-upper part of the interconnected keyholes became thinner at the later stage of the droplet entering the molten pool. At the later stage of the droplet entering the molten pool via free transition, the flow vortex at the bottom of the keyhole disappeared and the melt at the bottom of the keyhole flowed to the rear of the molten pool, however, the vortex remained during slight contact transition and contact transition.