Piezoresistivity And Application Of Polymer-Matrix Carbon Fiber Smart Layer

The dissertation was supported by the project of the Fundamental Research Fund for Central Universities "the research on the interface and constitutive theory of the carbon fiber smart layer with a dynamic sensing function"(No.2010-la-002), to in-depth study the piezoresistive effect of the polymer-matrix continuous carbon fiber smart layer. Then we made explorative theoretical analysis and experimental researching. The following conclusions and innovation can be obtained:1. The theoretical modal of the piezoresistive effect of the polymer-matrix continuous carbon fiber smart layer was established. The piezoresistive matrix was reduced in the situation of plane stress, and we determined the four piezoresistive coefficients. Then we designed of the sample specifications and test methods to solve the piezoresistive coefficients. Using the framework equipment to provide unidirectional strain field, then get the four piezoresistive coefficients:C11=3.17、 C12=3.11、C21=-6.73、C22=4.92. According to the results of experiment we did some correlative discussions to explain the reasons of existing the positive piezoresistivity and the negative piezoresistivity.2. Through the experiment tested out the sensing limit of the smart layer. After considering a certain safety coefficient, ensure the maximum working strain no more than6000με, while the smart layer owned higher sensitivity in the strain interval from0to3000με. Using ANSYS software to calculate and analyse the response of the smart layer when the rectangular thin plates were under different working conditions. Using A to show the sum of squares of the smart layer on the surface; B showed the sum of squares of the smart layer under the surface; C showed the sum of squares of all the smart layer. Through each mode of the solution to draw up the law figure of A, B, C as the load changed. According to the law figure to obtain the further conclusion:If we measured a certain A, the force at the center of the thin plate we need was the smallest; While the force nearby the right Angle plate we need was the biggest.3. To do load identification for the rectangular plate with four simply supported with the help of the piezoresistivity of the polymer-matrix continuous carbon fiber smart layer. Then put forward the corresponding method of the direct problem and the inverse problem. After that we did a practical example with the use of the parameter prediction method and the regularization least squares, all of the results can converge to the real value, it showed that the smart layer can be applied in engineering practice.