ALEXANDRU BOLCU, NICOLAE DUMITRU, ION CIUCA, MARIUS MARINEL STANESCU, DUMITRU BOLCU THE VIBRATIONS STUDY OF DAMMAR BASED COMPOSITE BARS REINFORCED WITH NATURAL FIBERS BY USING A NEW EULER - BERNOULLI THEORY In the paper it is presented a new Euler – Bernoulli theory based on an assymetrical distribution of strains towards the median plane, the area subjected to compression has a transversal stretching, while the area subjected to tensile has a transversal contraction. This theory takes into account the transversal contraction factors and consequently the eigenpulsations of bars vibrations with rectangular section depend on the ratio between the bars width and thickness. This theory is experimentally verified for Dammar based composite bars reinforced with cotton, flax, silk and hemp fibers. For the considered bars, we have experimentally determined the eigen frequencies and the damping factor values.
Keywords: composite bar, bar eigenpulsations, Euler-Bernoulli theory