Three-dimensional Braided Composite Material Health Monitoring Carbon Nanotube Wire Embedding Model And Its Characteristics

In the research,the use of carbon nanotubes yarns as sensors embedded in three-dimensional braided composites is the major subject of the whole paper based on the structural health monitoring system as foundation.The combination of carbon nanotubes yarns and three-dimensional braided composites as a whole model and the characteristics of the model of carbon nanotubes yarns are the key technologies.In this paper,the methods of combining carbon nanotubes yarns with 3D braided composites were described,which mainly includes the surface grid monitoring,the internal monitoring by axial sensor yarns,and the internal monitoring by braiding sensor yarns.In the method of adhering material surface monitoring,a grid pattern model has been established.It can reflect the stress state of carbon nanotubes yarns according to the attached grid structure and algorithm design,and provide a theoretical basis for the future research of carbon nanotubes yarns sensor on the surface monitoring work.In the method of internal monitoring by axial sensor yarns,the specific embedding methods of carbon nanotubes yarns into the 3D braided composites with five directions,whole five directions and six directions,were introduced in detail.An artificial immune algorithm to optimize sensors placement has been designed,it can improve the convergence rate,and better maintain the sensor global coverage.Compared with other intelligent optimization algorithms,the immune algorithm can ensure the fast convergence and keep the diversity of the population,and it can effectively overcome the problem of premature convergence in local search.In the braiding process,carbon nanotubes yarns can be braided in the composite,which can monitor structural health internally.Firstly,a kind of matrix algorithm has been built to calculate the carbon nanotubes yarns spatial node coordinates.Using C#language to develop and implement a named Matrix3DBraid graphics visualization computer simulation program,the program has the ability for batch computing all nodes coordinates of yarns at the same time achieving coordinate storage.Secondly,according to the output nodes coordinates by Matrix3DBraid simulation program,the nodes coordinates list can be made,a carbon nanotubes yarn sensor is expressed as L,these nodes can be used to establish a space Bezier or B spline curve.And the carbon nanotubes yarn space length can be obtained by the definite integral calculation of carbon nanotubes yarn L.Thirdly,through comparing the experimental yarn length value and theoretical value,analysis result was given to verify the validity of the theory.The research of carbon nanotubes yarns in 3D braided composites health monitoring system will be an important subject and has some significance in fields,such as damage localization,damage assessment and other foundation research work.