Effect of High Temperature on Mode I Intralaminar Fracture Toughness
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Date
2026
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National Institute of Technology, Silchar
Abstract
This study explored fracture behaviour of two types of glass-fiber-reinforced polymer (GFRP) – a pultruded I-beam and a hand-layup sheet – behave under high temperature. The pultruded profile contained about 73% glass fiber by weight with three different fiber layers (random mat, combined mat, and unidirectional 0° mat), while the hand-layup laminate had roughly 40% fiber with a 0° core and random outer skins. Mechanical tests showed that both materials are much stronger along the fiber direction than across it. Fracture toughness was measured using single-edge notch bending (SENB) tests at room temperature and after heating to 60 °C, 100 °C, 200 °C, and 300 °C. At room temperature, the critical stress intensity factor (K1c) was 26.5 MPa·mm1/2 for the profile and 22.6 MPa·mm1/2 for the laminate. After heating, the peak load rose slightly at 100 °C (possibly from extra curing) but fell sharply at 200 °C and 300 °C due to matrix breakdown; at 400 °C the resin melted completely. A 2D Abaqus model using CPS4R elements for the bulk GFRP and COH2D4 cohesive elements for the crack path, with Hashin damage, successfully reproduced the experimental trend – simulated peak loads dropped from 2.89 kN at room temperature to 0.78 kN at 400 °C. Damage patterns shifted from brittle at low temperatures to more ductile at high temperatures. Overall, GFRP works well up to about 200 °C, and the numerical model provides a useful way to predict its fracture behaviour under heat.