Chladni Figures Research Articles

Sound and Sight: Acoustic Figures and Visual Phenomena

The impact that the analysis of sound waves has made on theories of light is well known, and is touched upon here. However, the acoustic figures described initially by Robert Hooke in 1665 and in more detail by Ernst Chladni in 1787 (often referred to as Chladni figures) were instrumental in vision in two specific respects. First, their representation by Tyndall [1867 Sound. A Course of Eight Lectures Delivered at the Royal Institution of Great Britain (London: Longmans, Green)] in a book on sound resulted in the description of a visual illusion, the Hermann grid. Secondly, attempts to render the acoustic figures visible (on the basis of briefly persisting images) led to the discovery of instruments that could synthesise movement. These two developments are discussed in their historical contexts.

Circles in the sand: methods for reproducing Chladni's figures

No abstract

Effect of Smoke Source and Horn Configuration on Enhanced Deposition, Acoustic Agglomeration, and Chladni Figures in Smoke Detectors

A series of UL/EN based test fires was conducted in a two room/corridor enclosure to investigate the viability of methods for determining whether a smoke detector sounded under a variety of smoke conditions and to see if this methodology could be applied to a detector with a different horn configuration. The presence of enhanced deposition in the form of a black or orange-brown ring and agglomerates around the central opening of a smoke detector horn was found to be a reliable indicator that the horn sounded when it was exposed to smoke from eight standardized, single-substrate fuel sources including hydrocarbon pool, flaming polyurethane foam, and smoldering polyurethane foam fires. Determinations could generally not be made for detectors exposed to white or gray smoke generated by flaming paper, smoldering paper, flaming wood, smoldering wood, and smoldering cotton wick due to a general lack of visible soot deposition within the detector. Therefore, it is not recommended to use the absence of a black or orange-brown ring of enhanced deposition, in and of itself, as an indicator that the horn did not sound. Nevertheless, this conclusion can be reached when the absence of enhanced deposition is combined with evidence supporting the presence of flaming fuels that produce black, sooty smoke. Test series were conducted using two different smoke detector brands, each having a different horn configuration. Findings suggest that the same type of methodology for determining whether the detector sounded is applicable to both models. Chladni figures were not found on any of the smoke detectors, whether they sounded or not; hence, the absence of a Chladni figure was not an indicator that the detector did not sound. A smoke flow visualization technique was used to determine the mechanism that caused the observed enhanced deposition and agglomerates on horns that sounded during a smoke exposure. Additionally, a smoke box test series showed that the extent of observed soot deposition increased with increasing smoke exposure.

Enhanced Deposition, Acoustic Agglomeration, and Chladni Figures in Smoke Detectors

A full-scale house fire test was conducted to investigate the accuracy of two proposed methods for determining whether a smoke or carbon monoxide (CO) alarm sounded during a smoke exposure. One method involves examining the plastic case of the alarm's piezoelectric horn for locally enhanced soot deposition and agglomerated soot particles. The other method involves examining the metal disc of the piezoelectric horn for a Chladni figure. Pairs of detectors, each consisting of one detector with its battery properly inserted and the other with its battery disconnected, were placed throughout the house. Each of the properly charged detectors was monitored to determine if and when the detector sounded. It was found that the presence of locally enhanced deposition and soot agglomerates on the main central opening of the plastic horn enclosure of a smoke or CO detector was a strong indicator that the alarm sounded. It was also found that the use of Chladni figures on the piezoelectric discs as an indication of the smoke detector sounding was not an accurate predictor.

Chladni Figures For Completely Free Parallelogram Plates: An Analytical Study

This paper communicates the first comprehensive analytical study of the title problem. The Ritz method with admissible functions in the form of Legendre polynomials is used, and is shown to provide rapid convergence and highly economic eigensolutions for a given problem. The robustness of the method is demonstrated, and proof is given of its validity at extreme skew angles. Chladni figures are presented for the first six modes of plates with three different aspect ratios and six different skew angles, making a total of 108 cases. (Additional results can be inferred for two more plate aspect ratios, thus raising the total number of Chladni figures to 180.) Outstanding agreement is obtained between all the analytically derived nodal patterns from this work and the experimental work of other investigators. The dependence of frequency on the skew angle, the aspect ratio and the Poisson ratio is also investigated, and extensive results are presented in diagrammatic and graphical format.

The late-twentieth century resolution of a mid-nineteenth century dilemma generated by the eighteenth-century experiments of Ernst Chladni on the dynamics of rods

The late-twentieth century resolution of a mid-nineteenth century dilemma generated by the eighteenth-century experiments of Ernst Chladni on the dynamics of rods

Chladni Figures: Unusual Experiments in Sound

(1979). Chladni Figures: Unusual Experiments in Sound. Science Activities: Vol. 16, No. 3, pp. 9-12.

Charles wheatstone—experimental philosopher

Abstract Professor Sir Charles Wheatstone, F.R.S. (1802–1875) was originally destined for a career in the manufacture of musical instruments but he was more interested in the science of acoustics. He investigated Chladni's figures, the conduction of sound in solids and the action of ‘free reed’ instruments. Subsequently he turned to the electric telegraph and made fundamental studies in electrical science, especially in measurements. His practical contributions to electrical technology include many designs of telegraph and work on motors and generators.

Observation of Chladni Figures in Piezoelectric Ceramic Plates of Rectangular Form

Observation of the Chladni figures was made on a piezoelectric ceramic plate which may be used as a piezoelectric transformer. Many spurious vibration modes were easily excited besides the normal mode. Those spurious modes were found to be the thickness flexure mode. The position where the transformer is to be supported could be determined from the Chladni figures. The resonant frequencies of the spurious mode were in better agreement with the calculated values from the frequency equation of a rectangular beam vibration in the flexure mode rather than with those from Rayleigh-Lamb equation.

LAWRENCE'S “CHLADNI FIGURES”

LAWRENCE'S “CHLADNI FIGURES”

Consolidation of the Chladni figure and interferometry methods for the investigation of the amplitude and configuration of piezoelectric plate modes

Consolidation of the Chladni figure and interferometry methods for the investigation of the amplitude and configuration of piezoelectric plate modes

Photogrammetric measurements of dynamic displacements

The feasibility of the determination of the patterns of vibrations of a plate by means of stereophotogrammetric methods was established. A square plate, free on all edges, was vibrated in resonance at the first three observable modes and simultaneously photographed by a pair of cameras by means of a rapid-flash tube. Chladni figures were used to establish a datum plane, and measurements on the pair of photographs were used to compute displacements on a set of grid intersections scribed on the plate.

Chladni Figures—A Study in Symmetry

Chladni Figures—A Study in Symmetry

Production of Chladni Figures on Vibrating Plates Using Continuous Excitation

A method of producing Chladni figures by continuous excitation is described. Thin metallic plates are placed in the sound field of a 15-watt (or higher) loud-speaker driven by an audio-oscillator and power-amplifier combination. Advantages of this method, especially for demonstration purposes, are enumerated.

Criteria of Excellence in Violins

This report continues a series from the Harvard Laboratories of which the last was published in our Journal in January, 1941 (Watson, Cunningham, and Saunders). Recent work has produced the response curves of several excellent old and new violins, and also the rates of decay of a few of their tones. Some of these results will be shown. They disclose considerable differences in decay constants among both old and new instruments. Low damping implies greater volume of sound and an easier though slower response. Loudness (without deterioration of quality) is considered very desirable. This was demonstrated in a test conducted by two of the best violinists in this country on a large group of new instruments. The best of these were later measured by us, and showed relatively high emission in the lowest octave, and more uniformity than usual up to 4000 c.p.s. Experiments are now in progress in several places on the effects of varnish, etc., on the damping of vibrations in wood. The Chladni figures in a violin-shaped plate recently studied by J. A. Kessler (not yet published) make it clear that vibrations across the grain of the wood (whose damping is known to be very high) are as important as those across the grain. Lowering the damping of the wood by special treatment should increase the sound emission as a whole at the risk of increasing the unpleasant weakness of tones occurring between resonant peaks; but the experiment is decidedly worth trying.

The production of chladni figures by means of solid carbon dioxide. Part 1: bars and other metal bodies

Chladni figures can be very readily produced by means of solid carbon dioxide: some photographs of results obtained on metal objects of various shapes are shown. The frequencies of the vibrations excited in objects of low fundamental tone usually lie between about 1000 and 4000. The theoretical implications of this fact are considered.

The velocity of sound in sheet materials

Chladni's figures have been produced at frequencies up to 20,000 by means of magnetostrictively excited tubes or rods of nickel. The velocity of sound in sheets of brass, iron, lead, ebonite, celluloid, cardboard and other materials has been measured with considerable accuracy by this means.

XXIV. On the calculation of Chladni's figures for a square plate

XXIV. <i>On the calculation of Chladni's figures for a square plate</i>

A Dictionary of Science: comprising Astronomy, Chemistry, Dynamics, Electricity, Heat, Hydrodynamics, Hydrostatics, Light, Magnetism, Mechanics, Meteorology, Pneumatics, Sound, and Statics

THERE are Dictionaries and Dictionaries. We have had occasion to expose the shortcomings of some books that are called by this name; it is a far pleasanter task to direct attention to the merits of a work like the one before us, which really deserves its title. Mr. Rodwell's “Dictionary of Science” is a repertory of facts connected with physical science, which will be invaluable to the student. From Chemistry to Chladni's Figures; from Thermo-dynamics to Turacine, scarcely a term will be met with in scientific works, of which the learner will not here find an explanation. The articles have the great advantage of being short, and presenting the salient points of each subject at a glance before the reader's eye; and that their scientific accuracy may be relied on, is guaranteed by such names (amongst others) as those of Mr. Crookes, Prof. Guthrie, and Mr. Wormell in the list of contributors. To illustrate the style of the book, we cannot do better than select two of the shorter articles. The first is on a subject which has recently been discussed in these columns:— A Dictionary of Science: comprising Astronomy, Chemistry, Dynamics, Electricity, Heat, Hydrodynamics, Hydrostatics, Light, Magnetism, Mechanics, Meteorology, Pneumatics, Sound, and Statics. Edited by G. F. Rodwell (London: E. Moxon and Co., 1871.)