The Influence of the Outer Shell on the Strength of an FDM Rod With a Low Filling Percentage

The purpose of this work is to evaluate the effect of the outer shell of a rod made using FDM printing on its static strength under central tension. The discrete filling structure of the internal volume of the part is determined by the specifics of the FDM printing. The specified geometry and dimensions of the part are provided by the outer shell. It is not possible to correctly assess the strength of such a part using existing calculation methods. Experimental studies were conducted to achieve this goal. Since thermoplastic materials are used for the manufacture of rods using FDM technology, GOST for tensile testing of plastics was adopted as the basis for selecting the shape and size of samples and conducting tests. With the same percentage of filling of the inner volume of the samples, the thickness parameters of the outer shell changed. According to the test results, it was found that the overall strength of the rod, all other things being equal, is influenced by the proportion of the shell area relative to the nominal cross-sectional area of the sample and the nature of the shell thickness distribution along the contour of the section. The dependencies determining the influence of the parameters of the outer shell of the rod on its strength properties were revealed. The knowledge gained is a prerequisite for the theoretical substantiation of the influence of the parameters of the shell of the FDM rod on its strength.