Stress based FE is not popular. Why?

In displacement based FE we assume a suitable displacement function to model the actual displacement. We shall have a prior understanding on the displacement as the displacement constraints help us to assume the displacement field. More over the displacement field should satisfy the compatibility similarly if stress based based FE is employed the stress field should satisfy the equilibrium which is not easy to assume. Hence Displacement based FE is more popular and widely used..

 Hi Ramdas,

 Displacement-based modesl:

- Dispalcement field is approximated.

- Compatibilty conditions are required on element interfaces: since nodal values such as displacements, rotations can be determined directly from displacement field, these conditions can be easily satisfied by the assembly scheme.

Stress-based models:

- Stress fields are approximated.

- Equilibrium conditions on element interfaces are needed. To do this, we must derive the general forces (nodal forces)  which must be equilibrium with the stress field. This is not easy, especially for high order approximations. This can be explained why stress-based elements are not popular compared with the displacement ones. However, in the field of plastic limit analysis both kind of models are well developed.

Regards,

Canh Le

Canh V. Le, PhD Student
Computational Mechanics and Design (CMD)
Department of Civil and Structural Engineering
The University of Sheffield
Mappin Street,
Sheffield, S1 3JD, UK.
Phone: GB +44 1142225724

flexibility method is used in frames as you can get the moments and forces directly there is no need to calculate displacements which are often not of much use (except under serviciability) for civil engineers. I agree with your remark