In order to evaluate if a design is robust and meets design margins, engineers use a variety of analytical tools. Often a product’s duty cycle is not perfectly characterized but the statistics of a lifetime of excitation are known.
These excitations can cause fatigue when system level dynamics are excited. It is very important to understand how a system responds to these excitations and how natural frequencies interact with each other.
Power spectral density (PSD) analysis, more commonly known as random response analysis, is used to determine stresses and strains in a system that is subjected to random excitations.