Nonlinear Treatment in Linear Dynamics - Lesson 4

Designing and analyzing engineered products may require a variety of different types of analysis, such as nonlinear static or linear dynamic analysis on the same system. If we have a model already prepared for nonlinear analysis, can we use it directly for a linear dynamic analysis? Also, in many engineering applications, the dynamic behavior of a structure based on a prior linear or nonlinear status may be of interest. Although we know that a linear dynamic analysis is linear, what should we do if a model contains nonlinearities? Do we need to change the numerical model? How will the nonlinear properties be treated in the linear dynamic analysis? In this lesson, we'll explore the answer to these questions in more detail and investigate the ways to include nonlinearities in linear dynamic analysis. We begin with a brief lecture and then move on to a workshop demonstration of an electronic enclosure.

Alternate video link.

Video Highlights

01:30 — Example of nonlinearities in linear dynamics

03:06 — Assumptions of linear dynamics

03:55 — Two approaches to utilize nonlinearities in linear dynamics

04:09 — Linear perturbation

05:16 — Contact nonlinearity treatment in direct modal analysis

07:15 — Contact nonlinearity treatment in linear perturbation (Pre-stressed Modal Analysis)

07:54 — "True Status" option in contact status of Pre-stress Modal

08:01 — "Force Sticking" option in contact status of Pre-stress Modal

08:16 — "Force Bonding" option in contact status of Pre-stress Modal

08:53 — Material nonlinearity treatment in linear dynamics

10:20 — Geometric nonlinearity treatment in linear dynamics

13:43 — How to check contact status using the Contact Tool

17:04 — How to change contact status in Pre-stress Modal

17:48 — Comparison table of modal behavior for various combinations of contact type and status

Simulation Files

Download the accompanying archived project file used in the video lesson here. The student version of Ansys simulation software can be downloaded for free here.