In the final thesis, we considered the bending of a composite beam consisting of several longitudinal layers. These kind of beams are typically used to reduce weight and adjust the desired properties of the material in thickness. We studied beams with two layers and several layers. In the first part, the theory of bending of thin beams is derived, to which Bernoulli's assumption of straight sections applies. We derived the relationship between the stress and strain state for arbitrarily large displacements and rotations in pure bending. At first we tested the theory on a few computational cases in which we considered that one layer in the support is heated up and therefore stretches. Then we tested the theory with an experiment in which one of the layers was highly deformed and attached to an undeformed layer. After release, this composite deformed into a circular arc. A comparison between theoretical calculations and experiments showed a good match between the two methods.