The mechanical behavior of symmetrical and thin elastic beams during a three-point bending test has been widely studied, however, most of the authors do not propose the domain of the solution and present results by means of analytical models without considering the verification to through an experimental design in addition to assuming negligible the thickness of the beam for the simplification of the problem. The previous approach led to analyze the following research question: How does the thickness influence the flexural behavior at three points of an elastic symmetric beam subject to large deflections? Through the present research work, the phenomenon of threepoint bending was studied in the case of large deflections in a photopolymer material taking into account the variation in thickness according to the following description: i. description of an analytical model adapted from Batista for flexural behavior, ii. Development of an experimental model to verify or refute the validity of the model. vi The results of the statistical analysis of the data show that the thickness (in the domain of the ASTM standards, for materials with sheet form as in the case of the conditions exist: specimens of thickness ≥1,6 mm and specimens with thickness.