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What Is a Modal Response?

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A modal response is how structures respond to varying types of vibration. Measuring modal response allows structural engineers to study and determine the best plan of action for an overall building, car, airplane, crane or theater. Different types of vibration are more prevalent in some structures than others, so it remains important for the engineer to study the modal analysis of all the materials used as well as what happens when everything is combined.

Sound Testing

Theaters are a good example of the need for testing noise vibration. Not only do the engineers need to make sure the structure can handle the sound vibration but also that the acoustics are maximized. The modal testing allows the engineer to see how the sound waves will interact and if any interference will be caused. Changes to the materials used can help reduce cross-waves, which distort and destroy sound integrity.

Vibration Testing

Vibration testing often determines the integrity of a vehicle during typical usage. This includes how all the pieces connect, the security of moving parts and bolts and change under pressure. Modal response works by applying various levels of vibration to single parts and gradually adding all parts. The testing applies as the pieces are manufactured and put together. Some parts might respond differently when attached to others, so the modal testing must take all scenarios into account.

Earthquake Engineering

As modal response evolved, engineers began utilizing the studies to help with earthquake safety. Modal response has been directly responsible for changes to building codes in order to make structures sturdy in the event of an earthquake. These codes are often utilized in areas, such as California, where earthquakes occur often. Even in a larger earthquake, buildings are now able to move with the seismic activity to help prevent devastation.

Dampening Effects

Modal response studies what can be added to structures in order to dampen or lessen vibration. The more the vibration can be limited the less likely the structure is to have an adverse reaction. Different padding, connectors and building materials are constantly developed and tested to determine the effectiveness against vibration. The modal response is then logged so engineers can choose from a vast array of materials to make each structure as sound as possible.


Pharaba Witt has worked as a writer in Los Angeles for more than 10 years. She has written for websites such as USA Today, Red Beacon, LIVESTRONG, WiseGeek, Web Series Network, Nursing Daily and major film studios. When not traveling she enjoys outdoor activities such as backpacking, snowboarding, ice climbing and scuba diving. She is constantly researching equipment and seeking new challenges.