Study on stress relaxation aging characterstics and modelling of CNTs/Al composite materials
Aiming at the forming requirements of carbon nanotubes-reinforced aluminum matrix composites(CNTs/Al)with high specific modulus and high specific strength for the new generation of lightweight panel structures for aerospace,the stress relaxation aging deforma-tion strengthening behaviors and its collaborative predictive modeling of shape and property of CNTs/Al were investigated.A series of stress relaxation aging tests covering elastic-plastic initial loading conditions(215 MPa,390 MPa,and 4％,6％)were conducted on CNTs/AA2024 at 130 ℃.The results show that the stress relaxation curves of CNTs/AA2024 present a short initial variable rate relaxa-tion stage(2.5 h)and a subsequent stable rate relaxation stage.In the plastic stage,the stress relaxation amount does not increase signif-icantly,which may be due to the hindering of dislocations by CNTs.Under the initial stress of 390 MPa,the yield strength of the material increases with ageing time,reaching the peak ageing state at about 5 h,with the yield strength of 485 MPa,and no obvious over-aging oc-curs until 16 h.Under the same aging time,the yield strength of CNTs/AA2024 increases with the increase of the initial stress,and the yield strength improvement effect is more obvious(576 MPa)in the plastic loading stage,mainly due to the synergistic effects of work hardening and dislocation-induced precipitation strengthening.Furthermore,a unified constitutive model for the stress relaxation aging of CNTs/AA2024 was proposed to realize the synergistic prediction of stress relaxation deformation,aging strengthening and key microscopic variables.
NETL
NSTL
万方数据
维普
