Related Experiment Video
Updated: May 12, 2026
09:39
Characterizing Dissipative Elastic Metamaterials Produced by Additive Manufacturing
Published on: June 28, 2024
Acoustical spring effect in a compliant cavity.
B Issenmann1, A Auberon, R Wunenburger
1UMR 5798, Université Bordeaux, LOMA, F-33405, Talence, France. bruno.issenmann@univ-lyon1.fr
The European Physical Journal. E, Soft Matter
|April 23, 2013
Summary
This study reveals the acoustical spring effect in a water cavity using surface waves. Researchers observed that acoustic radiation pressure influences surface wave amplitude, demonstrating added stiffness and potential parametric instability.
Area of Science:
- Acoustics
- Fluid Dynamics
- Surface Physics
Background:
- The acoustical spring effect, analogous to its optical counterpart, arises from the interplay between cavity length and stored acoustic energy.
- Acoustic radiation pressure is a key factor in this phenomenon, influencing the dynamics of fluid interfaces.
Purpose of the Study:
- To conduct the first dynamic investigation of the acoustical spring effect in a compliant cavity.
- To analyze the role of acoustic radiation pressure in modulating surface wave behavior.
- To explore spontaneous surface oscillations and their potential causes.
Main Methods:
- Utilizing a spherical ultrasonic transducer immersed in water to create a compliant cavity with a free liquid surface at its focus.
- Employing surface waves as a probe to investigate the acoustical spring effect and its associated stiffness.
- Measuring surface wave amplitude variations and back-scattering patterns in response to cavity length changes.
Main Results:
- Observed a direct correlation between surface wave amplitude and the variation of acoustic radiation pressure with cavity length, indicating acoustic spring stiffness.
- Demonstrated that surface response to cavity length variations primarily results in added stiffness, increasing the real part of the surface impedance.
- Reproducibly observed spontaneous surface oscillations when the liquid surface was moved out of the focal plane, suggesting parametric instability.
Conclusions:
- The acoustical spring effect is dynamically validated through surface wave analysis in a compliant water cavity.
- Acoustic radiation pressure significantly contributes to the added stiffness observed in the system.
- Parametric instability may be responsible for spontaneous surface oscillations under specific conditions, opening avenues for further research.
Related Concept Videos
01:14Sound Waves: Resonance
Resonance is produced depending on the boundary conditions imposed on a wave. Resonance can be produced in a string under tension with symmetrical boundary conditions (i.e., has a node at each end). A node is defined as a fixed point where the string does not move. The symmetrical boundary conditions result in some frequencies resonating and producing standing waves, while other frequencies interfere destructively. Sound waves can resonate in a hollow tube, and the frequencies of the sound...
01:28Standing Waves in a Cavity
A household microwave and lasers are examples of standing electromagnetic waves in a cavity. When two conducting metal plates are placed parallel at the nodal planes, it creates a cavity where standing waves are formed. The cavity between the two planes is analogous to a stretched string held at the points x = 0 and x = L. Here, the distance 'L' between the two planes must be an integer multiple of half of the wavelength. The wavelengths that satisfy this condition are given by:
01:16Anatomy of the Ear
Auditory sensation, commonly called hearing, involves the transformation of sonic waves into neural impulses facilitated by the structures of the auditory organ. The prominent, flesh-like structure on the side of the head, called the auricle, directs sound waves towards the auditory canal. The auricle is often mislabeled as the pinna, a term more aligned with mobile structures like a feline's external ear. The auditory canal penetrates the cranium via the external auditory meatus of the...
01:17Sound as Pressure Waves
Sound waves, which are longitudinal waves, can be modeled as the displacement amplitude varying as a function of the spatial and temporal coordinates. As a column of the medium is displaced, its successive columns are also displaced. As the successive displacements differ relatively, a pressure difference with the surrounding pressure is created. The gauge pressure varies across the medium.
The pressure fluctuation depends on the difference in displacements between the successive points in the...
The pressure fluctuation depends on the difference in displacements between the successive points in the...
01:19Concept of Resonance and its Characteristics
If a driven oscillator needs to resonate at a specific frequency, then very light damping is required. An example of light damping includes playing piano strings and many other musical instruments. Conversely, to achieve small-amplitude oscillations as in a car's suspension system, heavy damping is required. Heavy damping reduces the amplitude, but the tradeoff is that the system responds at more frequencies. Speed bumps and gravel roads prove that even a car's suspension system is not immune...
01:17Frequency of Spring-Mass System
One interesting characteristic of the simple harmonic motion (SHM) of an object attached to a spring is that the angular frequency, and the period and frequency of the motion, depend only on the mass and the force constant of the spring, and not on other factors such as the amplitude of the motion or initial conditions. We can use the equations of motion and Newton's second law to find the angular frequency, frequency, and period.
Consider a block on a spring on a frictionless surface. There...
Consider a block on a spring on a frictionless surface. There...