6. PMASS element free vibration tests

This free vibration tests check the PMASS6 point mass elements. The tests compute the first n eigenfrequencies of a clamped beam with various configurations of PMASS6, or equivalent RBE elements. The beam is massless and acts as a spring for the PMASS6 and RBE elements.

  • Clamped beam with PMASS3, PMASS6, or RBE element at the tip.

  • Clamped beam with a PMASS6 or RBE element at the tip with an offset y in the x-y plane (DOF's 3 4 5 eliminated) and wth an offset in the x-z plane (DOF's 2 4 6 eliminated).

  • Clamped beam with a PMASS3 element at the tip with an offset in y simulated by a rigid beam.

The beam dimensions can be consulted in the params.mdl file. The material is isotropic, and the beam is modeled with B2.S.RS elements. The mass is a cube of dimensions LX*LY*LZ and density RHO2 (see params.mdl) and is modeled with a single HE8 elemen (for the RBE tests).

The test compares equivalent configurations, i.e. PMASS6 vs. RBE without offset and PMASS6 vs. RBE with and offset.