Page 14 - Using ANSYS for Finite Element Analysis Dynamic, Probabilistic, Design and Heat Transfer Analysis

ChaPter 1

Dynamic analysis

Structural analysis is mainly concerned with finding out the behavior of a
physical structure when subjected to force. This action can be in the form
of load due to the weight of things such as people, furniture, wind, snow,
and so on, or some other kind of excitation such as an earthquake, shaking
of the ground due to a blast nearby, and so on. In essence all these loads are
dynamic, including the self-weight of the structure because at some point in
time these loads were not there. The distinction is made between the dynamic
and the static analysis on the basis of whether the applied action has enough
acceleration in comparison to the structure’s natural frequency. If a load is
applied sufficiently slowly, the inertia forces (Newton’s first law of motion)
can be ignored and the analysis can be simplified as static analysis. Structural
dynamics, therefore, is a type of structural analysis that covers the behavior
of structures subjected to dynamic (actions having high acceleration) load-
ing. Dynamic loads include people, wind, waves, traffic, earthquakes, and
blasts. Any structure can be subjected to dynamic loading. Dynamic analysis
can be used to find dynamic displacements, time history, and modal analysis.
A dynamic analysis is also related to the inertia forces developed by a
structure when it is excited by means of dynamic loads applied suddenly
(e.g., wind blasts, explosion, and earthquake).
Dynamic analysis for simple structures can be carried out manually,
but for complex structures finite element analysis can be used to calculate
the mode shapes and frequencies.

1.1 tutoriaL 1: harmoniC anaLysis
of struCture

In this tutorial, the harmonic analysis of a cantilever beam will be
addressed. Harmonic analysis is used to determine the response of a