Figure 1 shows a square frame model with no boundary conditions. The square frame is modeled with 4 bar elements for each arm. The natural frequencies of the lowest vibration modes except for the rigid-body modes are compared with the reference solutions given in the NAFEMS benchmarks. The vibration mode shapes are depicted in Figure 2.
Figure 1. Free square frame modelFigure 1. Free square frame model
Figure 2. Vibration mode shapesFigure 2. Vibration mode shapes
You can download the problem description, model file and analysis results in 3D pdf format.