Fatigue behavior of rigid polymeric materials and composites at room and elevated temperature

Abstract

In order to characterize the fatigue behavior of rigid polymeric materials, various thermoplastics and glassfiber reinforced plastics (thermoplastics and thermosets) were tested under alternating plane bending stresses at room (20°C) and elevated (50°C) temperatures. Increase in surface temperature and decrease in flexural rigidity of specimens were also measured during the fatigue testing. The results revealed that 1. Rigid polymeric materials can be classified into 3 groups according to their temperature rise characteristics (ΔT) and rigidity decrease (ΔE) during fatigue testing as follows: Group I. lower ΔT and ΔE: for unreinforced thermoplastics and bulk molding compound. Group II. higher ΔT and ΔE: for glassfiber reinforced thermoplastics and thermosets. Group III. higher ΔT and ΔE: for unreinforced thermoplastics. 2. Fatigue strengths of 107 cycles of these materials of groups I∼III are well correlated with their elastic moduli, respectively.