Studi Eksperimental Kekuatan Fatik Komposit Epoxy-Serat Kaca Akibat Beban Bending Putar Berulang

Abstract

Glass fiber reinforced polymer (GFRP) composites are increasingly utilized in engineering applications due to their high specific strength, corrosion resistance, and ease of fabrication. However, many structural components are subjected to cyclic loading during service, making fatigue behavior an important consideration in design. This study experimentally investigates the fatigue strength of epoxy–glass fiber composites under rotary bending cyclic loading. Composite specimens were fabricated using the hand lay-up method with E-glass Chopped Strand Mat (CSM) reinforcement and Epoxchon 1011 epoxy resin at a resin-to-hardener ratio of 2:1. Fatigue tests were conducted using a rotary bending machine operating at a constant rotational speed of 1000 rpm under bending loads of 10, 12, 14, 16, and 18 gf. The corresponding nominal bending stresses were 0.047, 0.056, 0.066, 0.075, and 0.085 MPa, respectively. Three specimens were tested for each loading condition. The results revealed a significant decrease in fatigue life with increasing bending load. The average fatigue life decreased from 17,565 cycles at 10 gf to 1,449 cycles at 18 gf. The obtained S–N curve demonstrated an inverse relationship between stress amplitude and fatigue life. Fractographic observations showed matrix cracking, fiber pull-out, interlaminar delamination, and fiber fracture as dominant failure mechanisms. Large voids generated during the hand lay-up process acted as stress concentrators and accelerated crack initiation. The results provide baseline fatigue performance data for epoxy–E-glass composites subjected to rotary bending loading and can be used as a reference for the design of lightweight structural components under cyclic loading.