Study On Carbon Nanomaterials Modified Self-Sensing FRP And Its Application

In order to study the self-sensing performance and its application of carbon nanomaterials modified FRP,two kinds of carbon nanomaterial epoxy resin composites were prepared by carbon nanotubes and graphene nanosheets.On the basis of the test and analysis of the mechanical and electrical properties of the two composites,the self-sensing performance of carbon nanomaterial epoxy resin composites was studied.The self-sensing carbon nanomaterials epoxy resin composites were used to reinforce continuous carbon fiber,and they formed self-sensing carbon nanomaterial modified CFRP,which can be used to monitor the health of concrete structure.The main research content is as follows:1.In order to get strengthened and conductive carbon nanomaterial epoxy resin composites,two kinds of carbon nanomaterials(carbon nanotubes and graphene nanosheets)were selected,the pretreatment method of carbon nanomaterials and the preparation technology of carbon nanotubes epoxy resin composite were improved,the carbon nanotubes epoxy resin composites and the graphene nanosheets epoxy resin composites were prepared,and their microstructures were characterized by scanning electron microscope.2.In order to ensure the carbon nanomaterial epoxy resin composites can be used in structural strengthening and self-sensing,the carbon nanotubes epoxy resin composites and graphene nanosheets epoxy resin composites with different mass fractions were made into tensile specimens;the stress-strain curve,tensile strength,breaking elongation and elastic modulus of the carbon nanomaterial epoxy resin composites with each mass fraction were measured by universal testing machine;the static volume resistivity of the two composites was measured by isolator resistance tester,and the percolation threshold of the two carbon nanomaterials in epoxy resin was determined.3.In order to check the self-sensing performance of carbon nanomaterial epoxy resin composites and determine a reasonable range of carbon nanomaterial mass fraction which made the composites self-sense better,under the conditions of simple tension and cyclic load,the stress-strain curve and resistance change rate of carbon nanomaterial epoxy resin composites were measured by universal test machine and isolator resistance tester at the same time;the resistance change rate-strain relations of composites with each mass fraction were established;the sensitivity and linearity of the selfsensing performance were determined by function fitting;carbon nanomaterial epoxy resin composites with several representative mass fractions were selected to measure the resistance responses under elastic cyclic loads and elastic-plastic cyclic loads;thereout,a reasonable range of carbon nanomaterial mass fraction which made the composites self-sense better was roughly determined.4.In order to check the sensing effect of carbon nanomaterial modified CFRP on concrete structural health monitoring and further determine the best range of carbon nanomaterial mass fraction in self-sensing modified CFRP,better ranges of the two carbon nanomaterials which made the composites strong and self-sense steadily were selected to reinforce continuous carbon fiber,forming the carbon nanomaterial modified CFRP;the stress-strain curve and resistance change rate of carbon nanomaterial modified CFRP were measured by universal test machine and isolator resistance tester at the same time;the characteristics of resistance responses under low-stress cyclic loads and high-stress cyclic loads were analyzed;carbon nanomaterial modified CFRP were pasted on the bottom of reinforced concrete beams,and their resistance responses under impact load on the top of beam were measured by isolator resistance tester;thereout,the best range of carbon nanomaterial mass fraction which made the carbon nanomaterial modified CFRP self-sense best was finally determined.