Structural Load - Aircraft Structural Loads

Aircraft Structural Loads

For aircraft, loading is divided into two major categories: limit loads and ultimate loads. Limit loads are often just flight loads and are further divided into maneuvering loads and gust loads. Ultimate loads are crash loads. Maneuvering loads are determined based on the performance limits of the aircraft whether imposed by the flight manual or by the actual aerodynamic performance of aircraft. Gust loads are determined statistically are taken from guidelines or requirements given by the applicable regulatory agency. Crash loads are loosely bounded by the ability of humans to survive extreme accelerations and are also typically taken from regulations.

Other loads that may be critical are pressure loads (for pressurized, high-altitude aircraft) and ground loads. Loads on the ground can be from adverse braking or maneuvering during taxi.

Finally, you cannot discuss aircraft loading without hearing about fatigue and damage tolerance. Aircraft are constantly subjected to cyclic loading. These cyclic loads initiate cracks and cause them to grow.

Thermal loading is rarely considered for the analysis of the primary structure of aircraft but it can become critical under extreme operating conditions and should be examined where materials of disparate coefficients of thermal expansion are joined.