AeroVironment’s Global Observer is an unmanned aircraft with the wingspan of a Boeing 767 but less than 10% of the weight designed to provide communications and sensing for flights lasting up to one week at up to 65,000 feet. With a maximum wing loading of only 3.5 pounds per square feet, the wingtip deflects greater than 22 feet at its design limit load.
MSC Nastran was utilized to develop nonlinear stress, structural dynamic and aeroelastic finite element models. The structural dynamics model was correlated to a ground vibration test, both of which had to accommodate the apparent mass of the air, which is atypical. The ultimate test of the nonlinear stress model was correlation with the static wing load test.
Fields in Patran are used whenever you need to define variable (non-constant) data. Applications include material properties, element properties, or load variations as a function of time, frequency, or spatial position. Fields are also helpful to map results between dissimilar meshes. Practical uses are briefly described below.