Bending deformation of polyethylene solid

The moduli obtained from the three-point bending tests for beam and plate specimens are apparently higher than the tensile Young’s modulus. For the beam specimen, a volumetric compression mode is observed in the inner zone of the bent specimen, whereas a uniaxial tension mode is observed in the outer zone. The flexural modulus in beam bending can be determined using the bimodular model, where the moduli of the innermost and outermost layers represent the bulk and tensile moduli, respectively. On the other hand, plate bending results in a strip-biaxial deformation during bending, with the bending modulus obtained from the cylindrical deformation. The principal factor influencing the flexural moduli of both specimens is the Poisson’s ratio.