Dear colleagues,

Dissipated energy plays an important role in the analysis of 4PB tests. It is well known that the total deflection Vt in a 4PB test has to be split up into 2 parts (Vb, Vs). The deflection Vb due to pure bending (and giving the horizontal strain) is the greatest. The deflection Vs (induced by shear forces in the beam) does not contribute to the horizontal strain and is small (Vs is 3-5% of Vb depending on the dimensions of the beam). The total dissipated energy in the 4PB device is given by the product of load, Vt (at the inner clamps), and the phase lag between force and deflection. But how do you calculate the dissipated energy due to shear at the bottom/top surface of the beam? A second question is: Does this dissipated shear energy contribute(or is it related) to fatigue damage? I'm curious what is your opinion about this.

Regards

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