Total control of the design process with non-linear FEM analysis
The design of metal components which will be loaded above the yield point is generally based on experience. Most Finite Element Method (FEM) software works with linear material properties. Calculations are therefore rarely used for components loaded above the yield point. "You need to use non-linear material properties if you are going to put both tensile strain and flow behaviours in an element," explains engineer Kenny Hoolwerf. "Our Femap NX Nastran allows us to perform linear, non-linear and contact analyses, and to use solid, shell and beam elements."
For example, the thickness of T-pieces on dredgers, pipes through which sand and clay flow with great force, is traditionally determined by empirical methods. One dredging operation wanted to use two dredging pumps in series, doubling the pressure in the T-pieces. "You can hardly rely on experience in those circumstances," says Hoolwerf, "but if you were to base the design on linear calculations alone, the resulting walls would be too thick." Idea developed the T-pieces in Femap, allowing them to be two thirds of the weight. "Non-linear FEM analysis allows you to confirm your empirical hunches, and gives you full control of the design process."
It is uncommon for components to be loaded beyond the yield point, but when it is necessary we can perform the necessary calculations.