Dynamic analysis results

Dynamic analysis conditions

Dynamic (Eigen) analysis is possible in case all of the following conditions are satisfied:

  1. Technical module No. 141 (Dynamic Eigenvalue analysis) is enabled
  2. At least one nodal concentrated or member distributed load is defined
  3. At least one "Mass" load combination contains load(s) described in #2 is defined
  4. Advanced analysis option "Dynamic Analysis" is enabled in analysis options


Dynamic analysis functions

1. Dynamic analysis is performed for lumping masses only, applied as nodal load(s):

  • lumping mass as nodal (not rotational) load
  • lumping masses as result of internal conversion from a distributed load into all free directions


Lumping mass:

Lumping mass


Each lumping mass reflects in one (natural frequency of vibration) Eigen form for each not fixed (free) degree of freedom. For more information see example.


2. Each applied member distributed load  during dynamic calculation process is automatically converted into the lumping masses as nodal concentrated load(s) applied in valid degree(s) of freedom. For more information see example 1 and example 2.


Every situation automatically generates subdivision of members, for example using tapered sections, could cause in the generation of unexpected quantity of Eigen forms



3. Symmetrical Eigen forms are not represented.


Eigen form values

By Dynamic analysis the following values are represented for each Eigen form:



Eigen value

Natural frequency of cycles in the system

Natural rotational frequency, [rad/s]

Cyclical oscillation frequency of masses in Eigen form. May be recalculated back from Eigen value as 1/(Eigen_value)

Natural frequency, [Hz]

Oscillation frequency of masses in Eigen form. May be recalculated back from natural rotational frequency as (natural_rotational_frequency)/(2*Pi)

Period, [s]

Oscillation period of masses in an Eigen form. May be recalculated back from natural as 1/(natural_frequency)