Understanding Resonance
Understanding Resonance
(OP)
I was wondering if anyone could explain some basic resonance ideas? If I'm designing a throttle body that incorporates a DC motor, is the concern that the motor may operate at or near the nat freq of the body, which would cause some body deformation? I'm assuming all objects have a NF right?, depending on mass of object. If an object is vibrated directly or by a component (if an assembly)at or near its NF is that when resonance ocuurs, what if the object was going through some vibration range, would it oscillate as it was transitioning through that NF range? I had the classes in school and worked the calculations but never really got a good applied, theoretical understanding of the concept. Any help is appreicated.





RE: Understanding Resonance
A simple example of excitation of a natural frequency is plucking a guitar string. The string vibrates at its natural frequency and because of damping the vibration reduces in amplitude over time.
An example of resonance is the old memorex commercial. Ella Fitzgerald adjusts the frequency of the note she is singing until it is the same as the natural frequency of a wine glass. The result is that the vibrations of the wine glass build up until it shatters. If some had tapped the wine glass the natural frequency would have been excited and the wine glass would ring at that frequency. But the constant excitation over stresses the glass causing it to shatter.
In general it is advised to keep mechanical structures out of resonance. I work with screw compressors that excite resonance in piping and silencers resulting in heavy plate steel breaking resulting in hydrocarbon leaks.
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RE: Understanding Resonance
RE: Understanding Resonance
I'm not sure if I agree with the statement that the first natural frequency of a structural has an amplitude that tends to infinity. I think your saying that the amplification of a structure excited by a force with a frequency equal to its natural frequency tends to infinity.
It is correct to say this (the fundamental mode) will have the largest amplitude. Also, other natural frequencies if clustered close to the first natural frequency may be non-trivial (for example during random vibration).
RE: Understanding Resonance
RE: Understanding Resonance