Development Of Multiaxial Fatigue Life Prediction Toolbox Built In MATLAB

This article chooses MATLAB as system development platform, to write a set of multiaxial fatigue toolbox. And make it applies to do multiaxial fatigue life prediction on key components for engineering and technical personnel and research workers also applies it as the platform of doing research on fatigue theories. Also, this paper is the research content of National Natural Science Foundation of China, so the development of fatigue toolbox based on MATLAB has important theoretical and practical value.First of all, make functional analysis of the fatigue toolbox, to determine functional modules of the toolbox and the son function of each function module; Second, make the input of the multiaxial load a deep research, consider what the user may input, and lay the foundation for future functional analysis. The display of multiaxial load module includes display of load path, the changes of the maximum shear strain, the changes of the maximum shear stress, the changes of the maximum principal strain, and the changes of maximum principal stress. It displays the user to observe the relationship between the load and the critical angle. This article provides these drawing modules.Third, according to the characteristics of the stress and strain under multiaxial loading conditions, determine the critical plane respectively by using the maximum shear strain amplitude plane method, the weight-averaged of the maximum shear strain plane, and the maximum principal stress amplitude plane method and the weight-averaged of the maximum principal stress plane method in low and high cycle fatigue field. The weight-averaged of the maximum principal stress plane method and the weight-averaged of the maximum shear strain plane use Coffin-Manson function and three-parameter S-N curse respectively to find the critical plane. The physics meaning is obvious.Again, study the handling process of the random load and the cycle counting. The multiaxial load simplifying procedure includes the collecting of peak and valley points and omitting of small loads. The cycle counting includes the equivalent range counting and rain rheological range counting. Next, the multiaxial fatigue life prediction model was established under the multiaxial loading. Three other kinds of the influent model and two new multiaxial fatigue life prediction model based on the concept of critical plane were given. Finally, based on the GUI programming in MATLAB environment, achieve the input of the multiaxial load and the display of multiaxial load, determination of the critical plane, method of multiaxial load simplifying and multiaxial cycle counting, determination of the random strain, the life prediction of the multiaxial load and other function modules. This fatigue toolbox has strong commonality and expansibility.