# Homework, Quizzes, Simulation Examples — Lesson 7

### Simulation Examples

Several practical simulation examples are provided here. These examples either directly present a modal analysis or indirectly show the application of modal analysis, like in a harmonic analysis or a random vibration analysis. Each of them comes with a description file, video instruction, and Ansys simulation file. Download the student version of Ansys software here.

#### (1) Drum Cymbal

As we mentioned before, the dynamic behavior of the cymbal after impact is a combination of all the mode shapes. Let's find these modal shapes using simulation. Download the zip file and extract the contents. Go through the Readme file. Follow along with the provided How To Video file.

The length of the wind turbine blade is usually over 100 ft. The vibration of a blade under wind flow is one of the key factors that designers are concerned with. Doing a modal analysis on a wind turbine blade design is usually the first step to test and validate the design. Download the zip file and extract the contents. Go through the Readme file. Follow along with the provided How To Video file.

#### (3) Circuit Board

Circuit boards in portable electronics, e.g., in moving vehicles, suffer from vibration from different sources. Modal analysis can tell us if the design of the circuit board avoids the range of destructive vibration sources. Download the zip file and extract the contents. Go through the Readme file. Follow along with the provided How To Video file.

#### (4) Modal Analysis of Guitar Strings

The pre-stress state changes the structural stiffness by adding a stress stiffness matrix to the original structural stiffness which changes the natural frequency of a structure. Guitar strings are pressed at different locations to produce different notes when plucked. Modal analysis can clearly show us the change in natural frequency due to pre-stressing. Download the zip file and extract the contents. Go through the Readme file. Follow along with the provided How To Video file.

#### (5) Modal Analysis of Burj Khalifa

The Burj Khalifa is currently the tallest skyscraper in the world (830 m). Modal analysis will serve as a critical primary requirement to understand the fundamental dynamics of the structure. In this simulation example, we will use a very simplified version of the skyscraper for illustration purposes only -- in no way is an accurate reproduction of the skyscraper. Download the zip file and extract the contents. Go through the Readme file. Follow along with the provided How To Video file.

### Homework

#### (1) Modal Analysis of a Drone Blade

Follow the steps to complete the modal analysis of a recreational drone blade. Observe the deformation pattern of the mode shapes. Are these deformations as expected? Which mode shapes are most significant in each direction? Answer the questions in the quiz related to this problem. Download the zip file and extract the contents. Go through the Readme file. Follow along with the provided How To Video file.

#### (2) Modal Analysis of Recreational Drone

Follow the steps to complete the modal analysis of a recreational drone. Try to extract different numbers of modes and decide if that number is sufficient. Answer questions in the quiz related to this problem. Download the zip file and extract the contents. Go through the Readme file. Follow along with the provided How To Video file.

#### (3) Modal Analysis of Lightweight Airplane

Perform a free-free modal analysis of a lightweight airplane. Solve the model for 15 modes and extract the deformation shapes. Also, answer the quiz questions relevant to this homework. Download the zip file and extract the contents. Go through the Readme file. Follow along with the provided How To Video file.

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