modal numerical analysis of helicopter rotor sample using holzer-myklestad method

Since rotor system of helicopters is responsible for producing lift forces and thrust, analyzing their vibrations is very essential. this research describes a method applied for developing a computer program to analyze coupled vibration of helicopter rotor. natural frequency and rotor blade mode shapes were analyzed by matlab software. in-plane, out-of-plane coupled and torsion vibration were also considered in this analysis. first, myklestad method, which is one of the most accurate ones to calculate vibration, was used to find governing equations of rotor vibrations. based on governing equation, vibration code was developed by matlab software. after that for validating the program, the obtained results were compared with numerical results using patran software, with maximum 4.264% error. in these problems, three beams in different geometric and material conditions with clamped end were defined. the innovation of this research is developing a matlab code to calculate the coupled natural frequencies and mode shapes of helicopter blade.