The von Mises model is often 
				 used to define the behavior of ductile materials based 
				 on the principle that yielding occurs when the shear stress 
				 reaches the threshold value. This model can be applied 
				 to truss, embedded truss and pipe elements as well as 
				 geotechnical elements. It can also be applied when simulating 
				 anchors, nails or steel pipe piles made from steel. 
				The von Mises model has the same limitation as the Tresca 
				 model when applied to soil materials; it does not consider 
				 of the effects of hydrostatic pressure and the yield stress 
				 is the same for compression and tension. Like the Tresca 
				 criterion, the undrained strength of saturated soil can 
				 be appropriately presented using the von Mises yield criterion. 
				 This model is useful because it does not have the mathematical 
				 difficulty or analysis complexity caused by the hexagonal 
				 corners of the curved surface on the Tresca criterion.  |