Research On Carbon Fiber Composite Self-sensing Performance Of Prestressed Concrere Structure

In the 21 st century, the damage accumulation and destruction problems of the infrastructure and large structure become increasingly severe, and the requirement of structural health monitoring(SHM) is becoming more and more strict. Carbon fiber reinforced plastics(CFRP) has excellent load-bearing and self-sensing properties, this provides the basis for the realization of the structure real- time health monitoring, and the research on self-sensing properties of CFRP has become hot spot in the field of civil engineering currently. Under the supports of National Natural Science Fundation of C hina, "Research on the self-sensing properties and application of prestressed concrete structure based on CFRP material(51478209)", this paper mainly studied the effect of manufacture craft and carbon powder dosage of modified resin matrix on the piezoresistive effect of CFRP sensor, and established a coupled mechanical and electrical model concerning piezoresistive effect of CFRP material. The main contents are as follows:1. The piezoresistive effect contrast test of CFRP sensor manufactured by the vacuum and brush coating crafts is designed, and each group contains three specimens. The effect of two different manufacture crafts on the initial resistance and volt-ampere characteristics of CFRP sensor is studied. Through the uniaxial tensile test of CFRP sensor, the strain is measured by extensometer and the specimen resistance is measured by the digital multimeter with two electrode method. The change rule of resistance versus strain and resistance change rate versus strain and its mechanism is summarized. The effect of two different manufacture crafts on the CFRP sensor indicators, such as linearity and sensitivity, is compared and analysed.2. Five groups of modified CFRP sensors with different carbon powder dosage are manufactured by brush coating craft. The change rule of initial resistance versus carbon powder dosage is summarized. The change rule of resistance versus strain and resistance change rate versus strain is studied and the effect of five different carbon powder dosage on the change rule is analysed. Then the effect of five different carbon powder dosage on the CFRP sensor indicators, sensitivity, is summarized and its mechanism is analysed in the micro angle.3. Based on the maxwell’s equations and variational principle, combined with structural strain energy of strain field and passive two dimensional electrostatic field potential energy theory, the mathematical physics model between the resistance(conductivity) response and the structure strain field is established. Further, the reliability of the mathematical physics model is validated. The work has great practical significance to the research on the constitutive relation between the resistance(conductivity) response and the structure strain field.