Electrical Performance Of Glass Fabric And Its Composite

With the rapid development of modern science and technology, the compositematerial has become one of the dominant materials in the21st century. The glass fiberreinforced composite materials have the advantages of light weight, high specificstrength and good corrosion, dielectric and heat insulation properties, which madethem widely used in the radomes, auto parts, PCB substrate and other fields. In theseapplication fields, the electrical properties play very important roles. In this thesis, aseries of research on the electrical properties of the glass fabric and its composites hasbeen done and the main contents are listed as follows.In the first part of the work, the dielectric constant model has been built based onthe capacitance calculation rule, the Peirce model and the RC cyclic circuit.Compared with the present models, the interweaving rule of the warp/weft yarns inthe fabric was taken into account in the new model. The results showed that for theplain weaving structure, the calculated dielectric constant was lower than theexperimental value by4%to5%, indicating they have relatively good agreement.Additionally, the modeling method could be further used for building the dielectricconstants of other weaving structure fabrics.In the second part of the work, to study the effect of structure configuration onthe electrical performance of the glass fabric and its composites, different structuresincluding different weaving structures and twists of the fabric and correspondingcomposites have been prepared and characterized. The results showed that the plainweaving twisted structure fabric and composite have the lowest dielectric constantsand dielectric losses as well as electromagnetic losses, which suggested that this kindof structure could be considered for use in the electrical field.In the third part of the work, to propose a new method for testing the damagedegree of the composite through the dielectric properties, the relationship between theimpact damage and the dielectric constant of the glass fiber composites has beeninvestigated. The results showed that as the times of impact test were increased, thedielectric constant of the composite was decreased. After12-time impact test, thecomposite dielectric constant was decreased by16.7%. Furthermore, the SEM photosof the damaged samples were conducted to detect the fracture modes of thecomposite.In summary, the electrical performances of the glass fabrics and its compositehave been investigated from the three aspects. Firstly, a new theoretical dielectric model of the fabric has been built. Secondly, the effect of the structureconfiguration on the glass fabric and composites has been studied. Finally, therelationship between the impact damage and the dielectric constant of the glassfiber composites has been investigated, which provided a new feasible way fordetecting the mechanical damage of the composite.