# Homework, Quizzes, Simulation Examples – Structural Dynamics – Lesson 4

### Simulation Examples

Several simulation examples are provided here. Each of them comes with a description file, video instructions, and Ansys simulation file. All of the simulations were conducted using Ansys software. Download the student version of Ansys simulation software here.

#### (1) Pendulum

The movement of a pendulum is a typical dynamic problem. For this simple pendulum simulation, can you estimate the natural frequency? You are encouraged to change the damping ratio in rigid body dynamics analysis and the friction coefficient in transient analysis to see how they influence the amplitude. Download the zip file and extract the contents. Go through the Readme file. Follow along with the provided How To video file.  #### (2) Windmill Fan Blade Modal Analysis

Modal analysis is the foundation of linear dynamics. It provides natural frequencies and modal shapes of an object or system, which are important components for harmonic and transient analyses. This simulation uses a windmill blade to illustrate modal analysis. Check the natural frequencies and the corresponding modal shapes. Can you find any patterns or correlations? Download the zip file and extract the contents. Go through the Readme file. Follow along with the provided How To video file.  #### (3) Random Vibration Analysis of a Circuit Board

Random vibration analysis (RVA) is a typical frequency domain related problem. This simulation demonstrates how RVA is applied to a circuit board to locate its critical points. This analysis is crucial for circuit boards that operate in many applications such as automobiles. You are encouraged to explore the model and check how a random vibration analysis is set up. Download the zip file and extract the contents. Go through the Readme file. Follow along with the provided How To video file.  #### (4) Apple Dropping From Rest

This simulation uses an apple dropping from rest to illustrate the effect of inertia. You are encouraged to explore the model and discover the relationship between acceleration, velocity, and displacement. Download the zip file and extract the contents. Go through the Readme file. Follow along with the provided How To video file. #### (5) Billiard Ball Impact

Billiard ball impact is a typical dynamic problem that involves impact, high inertia, and friction. This simulation demonstrates how finite element analysis can be used to predict the movement of billiard balls. You are encouraged to change the coefficient of friction between the billiard balls and the table to see how these changes affect the result. Download the zip file and extract the contents. Go through the Readme file. Follow along with the provided How To Video file.  ### Homework

#### (1) Earthquake Response of a Building

A response spectrum analysis (RSA) is a widely used approach in earthquake engineering to find the response of structures. A response spectrum is a plot of the maximum response of a linear one-degree-of-freedom (DOF) system to a given time-history input. This simulation demonstrates the process of doing an RSA to find the maximum response of a two-story building. Follow the steps in the readme file and the video to reproduce the simulation. Answer the following questions:

a. Is this simulation a time-domain or a frequency-domain problem?

b. Specify the inputs and outputs of the simulation. Interpret the outputs. How would the results benefit an engineer in building design? 