Aircraft Structural Mode Interaction

In this video, you will learn the interaction between airframe oscillation and the load alleviation systems, also known as Structural Mode Interaction.

Learn more at https://tamarackaero.com/insights/cat...

Subscribe on YouTube: http://bit.do/tamaracksubscribe

Follow us on Twitter:   / tamarackaero  

Follow us on LinkedIn:   / tamarackaero  

A very important topic to analyze in the design and certification of and aircraft equipped with a load alleviation system is SMI. SMI stands for Structural Mode Interaction. This is an interaction between the deformation of the aircraft airframe and the effect of the load alleviation or the flight control system. A load alleviation system generally speaking picks up signals from accelerometers or other sensors located on the airframe. Since the airframe oscillates in flight due to gusts or turbulence or maneuvers the flight control system or the load alleviation system can pick up these oscillations and they are fed back to the control law. This can lead into a detrimental interaction between the oscillations of the airframe and the forces that load alleviation system is feeding back into the airframe. So the role of the engineers is to design the load alleviation system such that this phenomenon, this detrimental interaction, does not occur. So one of the things to do is to design appropriate filters to filter out the vibration of the airframe or to design the control laws with the certain features to avoid this potentially catastrophic interaction.