Fatigue Spectrum for a Stiffened Composite Panel

A composite is a structural material that consists of two or more constituents that are combined at a macroscopic level and are not soluble in each other. One constituent is called the reinforcing phase and the one in which it is embedded is called the matrix. Such composites offer various advantages such as low weight, corrosion resistance, high fatigue strength, faster assembly etc and hence they are widely used in aircrafts. Various parts of the aircraft viz. wing, rudder, pressure bulkheads, fuselage skin and other minor parts. The study was on the testing of a stiffened panel, a component of the wing (Lower wing skin) of a transport aircraft.\ud The objective of the study was to develop a standardized load sequence that would be a representative for the load-time history in the considered wing component. The load sequence was obtained through comparison of various transport aircrafts. A general spectrum was derived which was converted into a stepped spectrum for testing purposes. Flight blocks and flight types were defined for ease of programming and execution.\ud The fatigue spectrum was derived based on a standardized spectrum published in literature and implemented in a computer program written in MATLAB computing environment