Strain Sensing Behaviors Of Gnps/Epoxy Flxible Sensor And Health Monitoring For Composite Materials

Fiber reinforced polymer composites have become the most important structure materials in many advanced areas,owing to their excellent specific mechanical properties.The awareness of the structure integrity and the prediction of remaining life of components could avoid disasters or predict sudden failure of composites.New and improved methods for early detection of damage and structural health monitoring?SHM?of composite materials may allow for enhanced reliability,lifetime and performance while minimizing maintenance time during a composite part's service life.GnPs/epoxy sensors can be coated on the complex surface of the formed composite materials without leading into defects in the composite structure promoting crack initiation and damage to the composite parts.Low solubility and weak dispersibility of GnPs within the polymer matrix make the dispersion process difficult.The preparation of soluble graphene and an effective fabrication process should be performed to realize the GnPs/epoxy nanocomposites based strain sensor.GnPs is in general easier and stable to prepare and less costly for mass production in us team.The conductivity,solubility and other indicators meet the requirements of our GnPs/epoxy sensors.And the dispersion was also better improved by optimizing ultrasonic time.The GnPs/epoxy mixture exhibited relatively low percolation threshold of 0.76 vol.%.Strain sensor mechanisms and strain mode influence on the electrical response were clarified and the characteristics of sensor was demonstrated via monotonic tensile and cycle loading-unloading tests.The monotonic tensile results suggested that there are three different linear change sensing stages,?1?0.2%?,?0.2%?0.6%?and?0.6%¹.2%?,the linear growth of the electrical response is softened while the linear tendency is enhanced due to increasing GnPs content,and it exhibits relatively high gauge factor of 11.81,15.25and 22.54 for 0.84 vol.%respectively in different sensing stages.During 1000 cyclic loading-unloading tests,the sensors behavior could be divided into two phases.The first one was no obvious change of max?R/R₀.Afterwards,in the second phase,the?R/R₀had a slight increase.The GnPs/epoxy sensor shows promising applications for the damage monitoring of structural composite in the field of aerospace.