Learning Forum

[gprosperi]

Hello everyone,

I have already searched through the forum and AnsysHelp for something that could clarify my doubts, but I haven't found anything that explicitly addresses it.

My question concerns the difference between 'large deformation' and 'large deflection'. In my specific case, I am using a linear elastic material with a 1D filamentous structure (circular cross-section) for a tensile test, where a displacement is applied. During the experimental test of the sample, considering the displacement and the geometry of the filament structures, large deformations and fiber rotations must occur before they break, which suggests that the system operates in a nonlinear regime.

By activating 'large deflection' to work in a nonlinear regime, I obtained results that are closer to the experimental tensile test scenario. This has raised my doubts:

1. Could it be said that the 'large deflection' option in the analysis settings corresponds to 'large deformation'?  Or what is the difference between theorical 'large deformation' and 'large deflection' as presented in analysis settings?
2. If the two concepts are indeed different, and I want to study large deformation, how is this defined during the simulation?

Thanks in advance!

[Shashidhar Reddy]

Hi,

Large deflection under analysis settings is same as large deformation. 

Small deflection and small strain analyses assume that displacements are small enough that the resulting stiffness changes are insignificant.

In contrast, large-strain/large deflection analyses account for the stiffness changes that result from changes in deflection (stiffness is a function of displacement).

Large deflection on (NLGEOM, ON (ANSYS help>Mechanical APDL>COmmand reference>NLGEOM) mainly activates the large-strain/large deflection nonlinearity based on element type.

For more deep information on background mathematics, you can refer to ANSYS help.

ANSYS help>Mechanical APDL>COmmand reference>NLGEOM

ANSYS help>Mechanical APDL>Theory reference>Chapter 3: Structures with Geometric Nonlinearities

ANSYS help>Mechanical APDL>Structural analysis Guide>Chapter 8: Nonlinear Structural Analysis

Hope it helps.

Thank you

Regards

Shashidhar, PhD