Analysis of the dynamic flexural behaviour of composite beams at low temperature

In this study, the dynamic flexural behaviour at low temperatures of beams of three carbon/epoxy laminates is evaluated, analysing the influence of temperature on the mechanical strength, stiffness and absorbed energy until failure. Three-point bending tests were performed under dynamic conditions at three different temperatures (20 °C, −60 °C and −150 °C), and the results were compared with those found under static conditions at the same temperatures. Both the mechanical strength and the absorbed energy decreased when the temperature diminished in all the laminates. No significant influence of temperature was noted on the effective flexural modulus. Two analytical models, using the classical laminated theory and the first-order shear deformation laminate theory, and a numerical model were used to analyse the experimental results of the tests. The models allowed to ensure the use of the equations, which do not consider inertia forces, to calculate the test parameters, and they provided the specimen support span to neglect shear effects. They served also to determine the origin of the noise present in the load measured in the dynamic tests.