Study On The Properties Of PA66-based Smart Material For Strain Monitoring

Strain detection is an important part of mechanics detection of civil engineering structures.Through the strain detection,the working condition of the engineering structure can be analyzed and evaluated,and the disease prevention measures can be put forward in time to prolong the service life of the structures.Meanwhile,long-term strain detection can provide reliable parameters for the study of engineering structure disease mechanism,which is instructive for the scientific design and construction of engineering structures.Based on the excellent mechanical properties of PA66(Polyamide 66),this paper studied the PA66-based smart material for strain detection,which provides a material basis for the real-time detection of mechanical state of engineering structures.Firstly,the material composition design as well as the mix proportion design of PA66,based smart material was studied.The types of raw materials and laboratory preparation process were determined.The structures of the test specimens were designed and the resistivity of the PA66 base was tested.The conductivity of the smart material was studied and the percolation curve was drawn.The percolation threshold of the PA66-based smart material was obtained.Secondly,the sensitivity of PA66-based smart material was analyzed.The effects of strain,temperature and humidity on the conductivity of PA66-based smart material were studied.The resistance response of the smart material under different external factors was analyzed.In addition,the cyclic tests of strain and temperature were carried out,and the reliability of the repeated response of the smart material was analyzed,and the mixing proportion of the smart material was optimized.Then,the mechanical properties of PA66-based smart material were analyzed.The tensile strength and tensile modulus of the sensitive materials were tested.In addition,the fatigue test was carried out,and the variation law of the smart material under fatigue loading was analyzed.Finally,based on the tunnel effect conductivity theory model,the strain resistance response model of PA66-based smart material was deduced with modified coefficient of strain by Simmons formula,and the response mechanism of the strain resistance of the smart material was analyzed.