# cdm.ing.unimo.it

### Strumenti Sito

wikifemfuchde2019:lesson_in_an_undefined_future

Full profile properties characterization of a generic section, based on the FE model of a segment.

Base model: 2 rows of elements, 10 mm thick in the z direction profile segment. asymm_sez_base_v000.mfd

Profile wall overall midcurve length: 391.65525 mm.

Profile wall thickness: 4 mm.

Material properties are set, along with the local element orientations.

Symmetry (symm_pxy_nz) and skew-symmetry (skewsymm_pxy_nz) constraints are set for the nodes at z=0, and two RBE2 are set for the nodes at z=t=10mm,

• one with free warping displacements, and constrained in plane motions, named rbe2_skewsymm;
• the other, complementary to the first and named rbe2_symm, exhibits constrained o.o.p. displacements, and free in plane motion.

Material is set as isotropic, linearly elastic aluminum (E=70000,$\nu$=0.3, $G=E/(1+\nu)$); however, the following procedure is valid for a generic monoclinic material, for which the xy plane, normal to the z profile axis direction, is a symmetry plane.

Axial stiffness and centroid position

symm_pxy_nz b.c. and the rbe2_symm RBE2 are activated.

A positioning constraint is added with respect to the xy in plane translations, and the o.o.p. rotation.

A z displacement equal to $t/E$ is imposed at the RBE2 control node, while its other degrees of freedom are constrained to zero.

A uniform unit stress condition should be obtained if the material is homogeneous.

A z reaction force component is obtained, that for an homogeneous material equates the cross sectional area. Such force is here called $F$.

Being the control node not positioned at the centroid, x and y components of the reaction moment at such control node are expected to be nonzero, and equal to

wikifemfuchde2019/lesson_in_an_undefined_future.txt · Ultima modifica: 2019/04/01 11:20 da ebertocchi