Rapid Fatigue Life Prediction for Nonlinear Loading and Structures

摘要

The goal is to develop a relationship between the linear response power spectral density (PSD) and the nonlinear response probability density function (pdf) of rainflow ranges. Tilford Advanced Engineering, LLC (TAE) has developed a modified Dirlik solution that utilizes an linear to nonlinear conversion relationship referred to (by TAE) as the 'pdf transfer function'. In summary, the function converts a linear pdf of rainflow ranges into a nonlinear pdf of rainflow ranges without the need to conduct time consuming nonlinear transient FE analyses. This conversion is accomplished by establishing a link between the linear and nonlinear systems. This link can take on several different forms. For example, the link can be a relationship between linear input pressure and nonlinear output stress at a particular element location. This link information is calculated ONCE for a particular plate configuration and stored for future use by the end user. TAE has generated this link data for three plate configurations as part of an evaluation of the proposed solution.