Mathematical modeling and experimental investigation of a composite beam failure-Case study

Composite materials have been extensively employed in the aviation industry in recent years. The application of new materials enables significant weight savings with improved mechanical characteristics. This is also very important in the field of development of unmanned aerial vehicles (UAV). In the design phases, it is necessary to perceive all the aspects that are important for the structure and consider different load cases. The relationship between weight and strength proved to be important. This means that detailed strength analyses of each structural part are indispensable. In particular, primary load-bearing structures must sustain all types of loads without fail. Failure of the structure can affect the motion of the UAV during the mission or lead to a crash and significant losses. This paper presents the research performed on the failure analysis of a composite beam of a novel UAV. During the testing phase, under an unpredictable load condition followed by a crash landing, failure of the structure occurred on a beam element. The study was performed to determine the cause of the failure of certain layers of the composite laminate, because the previous calculation showed that it met the criteria for which it was dimensioned. Based on the telemetry data and the impact load that was registered, a complementary numerical and experimental analyses were performed to determine what happened and why. Composite test specimens were extracted from the beam and subjected to standard tensile tests, in order to determine the actual mechanical characteristics of the layered material. The paper presents in detail the comparison of the results as well as the methodology used in this research.