Finite Element Modal Analysis of a Truss Structure 

Steel and Aluminum 

were compared to evaluate the influence of material selection on 

natural frequencies while maintaining identical geometry, mesh, and boundary conditions.  

Comparison of the First Five Natural Frequencies:

      Material         Mode1       Mode2        Mode3        Mode 4        Mode 5 

E=210 GPa , ρ=7850 kg/m³      Steel                1152        1666           3136            3798            4189        Hz

E=69 GPa   , ρ=2700 kg/m³    Aluminum        1125        1629           3061            3710            4106        Hz

 The first five natural frequencies differed by only approximately 2%, 

indicating that the dynamic response was governed primarily by 

the specific stiffness (E/ρ) rather than Young's modulus alone.

Geometry had a greater influence on modal response than material substitution. 

• The study assumes linear elastic behavior, idealized pinned–roller supports, and free vibration without external excitation or damping .