Investigation of the vibration and bending behavior of a composite beam with defective layers using analytical and finite element method

Composite materials are used in engineering applications such as aerospace, space, transportation, construction, electronics and food industries due to their light weight, high strength and shape retention, structural and impact resistance, high flexural stiffness, strength and energy absorption. In recent years, the use of low-weight, high-strength composite materials required by the aviation industry has become quite widespread. Especially layered composite materials have an important place in this field. One of the most important problems in composite materials, which have started to be used quite frequently, is that the theoretically calculated values do not match the experimental results. One of the main reasons for this is that some faulty productions that are not taken into account theoretically during the production phase affect the mechanical properties of the composite part. In this study, a composite layer with 30% lower mechanical properties than the other layers was created to represent some defects caused by production and this layer was referred to as the defective layer. The vibration and bending behaviors of the composite beam, which is considered to consist of ten layers, were investigated analytically and by finite element method by changing the position of the defective composite layer on the beam. Symmetric and asymmetric layups, which are commonly used in the literature, were used as layer layups. Graphite/epoxy and boron/epoxy were selected as materials for the composite beam and all solutions were given for both material types. As a result of the study, the results obtained by analytical solution and finite element method are very close to each other. For both graphite/epoxy and boron/epoxy, the maximum collapse value increased and the natural frequency value decreased as expected when the defective layer was added to the composite beam. It has been determined that the location of the defective layer in the composite beam has a significant effect on the bending and vibration behavior in both symmetric and asymmetric configurations, and the results are given in detail.