On the Temperature Increase of Fiber Reinforced Plastics under Uniform Plane Bending Fatigue Test

Abstract

When a material is subjected to repeated loads, mechanical energy is consumed inside of the material by transforming into other types of energy such as heat and sound. As the thermal conductivity of FRP is low, a part of the loss energy is stored inside as heat, and the temperature of FRP increases. Since FRP is a sensitive material to its environmental temperature, it is important to investigate such temperature increase of FRP during fatigue.
If the temperature increase of FRP under repeated loads is caused by the heat equivalent to the internal loss energy, it is affected by such factors as kinds of resin and glass cloth, glass content, constitution of laminate, stress amplitude and cyclic frequency. In this paper, the following problems are discussed. (1) The temperature increase of specimens in the static tensile test, (2) the relations between the constitution of laminates or stress amplitude and the temperature increase of specimens in the fatigue test, (3) the temperature distribution in the inside of specimen in the early period of fatigue test, and (4) the effect of the temperature increase of composite laminate on its fatigue behavior. The temperature measurement was made with an infra-red radiation thermometer, which is capable of measuring surface temperature of objects without mounting sensors on their surface.