Effect of cork powder concentration and service temperature on strength characteristics and failure modes of tubular adhesively bonded joints

The current study investigates the synergistic influence of cork powder and temperature on the strength characteristics of tubular adhesive joints subjected to pure mode-II failure. Two distinct joint configurations, SteelCPVC and Steel-PVC, were employed in the study. The adhesive matrix consisted of Araldite-LY-556 and hardener AD-22962, with cork powder serving as the filler. Various proportions of cork powder, specifically 0.25 wt%, 0.50 wt%, 0.75 wt%, and 1 wt%, were incorporated into the adhesive mixture. Test samples were prepared for each configuration by using the modified adhesive followed, by a curing step at an elevated temperature. Tensile tests were conducted at four different temperature settings: 25 degrees C, 50 degrees C, 75 degrees C, and 100 degrees C, by utilizing a universal testing machine (UTM) equipped with a thermal chamber. The results revealed that, in the case of the Steel-CPVC configuration, the failure load characteristics of the joint exhibited an increasing response at lower cork concentration of 0.25 wt%, irrespective of the service temperature. However, was negatively impacted with the further increase in cork concentration. A maximum improvement of 53.48 % in failure load compared to the neat adhesive case at 25 degrees C was reported. Notably, the influence of cork powder persisted even under elevated temperature conditions, hence suggesting that that the impact of cork filler reinforcement is independent of service temperature. For the Steel-PVC joint layout, an entirely opposite trend was observed were both the increase in concentration of cork filler and service temperature significantly reduced the strength compared to the control case.