Steel String Research Articles

Microscopic Examination of Play-Worn Steel Music Strings

The wear tests on the strings made from ASTM‐A228 music wire were performed by using baglama, a stringed instrument. These tests named as play‐tests were carried out by reciprocating‐sliding with finger on Do major and contrariwise scales for different durations at andante moderato speed of 100 beat per minute and by plucking with the plectrum under steady environmental conditions. The increase in the electrical resistance of the string proved that the steel string suffered a massive loss as a result of play‐wear. Wear tracks obtained via SEM showed that the level of surface damage increased and became more pronounced depending on the beat amount. The results of the present study show that tribologists and acoustists should focus on wear‐acoustic relationships of strings. Because almost all kinds of data obtained about the surface wear of music strings can also shed light on all stringed instruments.

일렉트로어쿠스틱 기타용 광 픽업의 개발

A guitar pickup is a transducer that converts string vibration to an electrical signal. The magnetic and piezo pickups are the most commonly used for the respective electric and electroacoustic guitars. The magnetic pickups are prone to magnetic interference between the steel strings and permanent magnets, while the piezo ones are not free from signal inference between the strings. Thus, this paper presents the development of an optical pickup for the electroacoustic guitar. The proposed optical pickup has the top-to-bottom structure. It uses two of Infrared (IR) Light Emitting Diode (LED) and one photodetector. The developed optical pickup is subjected to the evaluation with commonly used piezoelectric pickup. It becomes obvious that SNR with the optical pickup is increased by 45 percent in average, compared with the piezoelectric pickup. It can be concluded that the developed optical pickup has a potential to be applied to the acoustic guitar.

A New Measuring Device and its Application on Surface Deformation Measurement of Concrete Shaft Lining

In light of the shortcomings present in the measuring devices of shaft lining surface deformation, a shaft lining surface deformation measuring device was proposed. With a protective cap to reduce the influence of external environment, the measuring device can reflect the deformation of shaft lining according to the tautness of a strain steel string. Featuring by its simple structure, operational convenience, and low cost as well, the device has been applied to the auxiliary shaft of Maiduoshan mine, Ningxia, China. The upper part of Maiduoshan auxiliary shaft had been constructed using mine tunneling method, before the bottom part of large water inflow section been constructed using freezing method. The deformation of the completed shaft lining was measured during the freezing method construction, to provide important references for technical personnel taking reasonable protective actions.

Late April, Full Moon, Scruggs Boy on the Front Porch Devising—1932

Late April, Full Moon, Scruggs Boy on the Front Porch Devising—1932 R. T. Smith (bio) Fireflies sing love songs without a note, but the boy is learning to listen and touch steel strings like a secret. Near the greening fig tree jeweled copperheads crawl, their tongues tasting fragrant air. He catches it in a chord. The white pines are candling, their new cones a-bristle, sharp against the evening. His fingers know the feeling. When late light rises behind the ridgeline’s spruce, cows salute it with moon, moon, but he cannot catch that roundness full as a gospel tambourine with fingers clenched like claws. He tries another grip, a tickle, three fingers on the right hand freeing what the left hand strangles. The whip-poor-will in the privet can hear a soul letting go and touch it with three slip notes before it flees. The boy aches to soothe that ghost in the trees, [End Page 98] to brush aside sharp leaves and watch the bird perched and yearning, to hear its highlands minor melody, but even the lucky mortals never see one airborne as we frail and frail against the dark. Earl leans forward, his fingers form a bird of a different feather. Silver notes all along the banjo dazzle and spark. [End Page 99] R. T. Smith R. T. Smith edits Shenandoah and is Writer-in-Residence at Washington and Lee University in Lexington, Virginia. His fourth collection of stories, Sherburne, was published this year, and his fourteenth collection of poems, The Red Wolf, is forthcoming. Copyright © 2012 Berea College

Experimental and numerical study of peculiarities at high-velocity interaction between a projectile and discrete bumpers

A high-velocity impact interaction of a polyethylene projectile (15 mm diameter) and aluminium projectile (6.35 mm diameter) with string and mesh bumpers (made of steel strings of 0.5–1.0 mm in diameter) was investigated experimentally and numerically. The study was aimed on detecting the projectile fragmentation peculiarities during projectile interaction with discrete bumpers. Since polyethylene has lower penetration resistance than aluminium, the effects inherent to discrete bumper penetration into the projectile must be more obvious for polyethylene. The string bumper is a set of parallel strings lying in a plane. The geometry of the string bumper which is simpler than the geometry of the mesh one also allowed one to get more understandable distribution of fragments on a thick aluminium witness-plate which was imposed behind the studied bumper to register the results of impact interaction for further analysis. The projectile velocity varied in the range of 1.7–3.8 km/s. The geometrical properties of such bumper-projectile system were characterized by two geometrical parameters: the parameter κ characterizing the bumper discreteness and equal to cell aperture-string diameter ratio, and the parameter ɛ defining the average number of cells falling within the projectile diameter. According to the experiments, the projectile destruction on string and mesh bumpers is especially distinguished by the accompanying formation of jets of fragments which are ejected from the front part of the projectile along and across its movement direction. The number of the jets correlates with the number of discrete bumper cells arriving at the projectile. The jets intensity depends on the impact velocity and values of the both geometrical parameters κ and ɛ; the action of the jets on the witness plate (evaluated by the craters depth) can exceed the action of the remaining projectile mass. The numerical modelling evaluates the revealed cumulative effect as follows: the velocity of the fragments in the jets exceeds the original projectile velocity up to factor of ˜1.5 in case when the projectile is aimed towards a cell centre. The experiments and calculations show that projectile destruction and fragmentation on the string and mesh bumpers are characterized not only by the formation of the jets ejected from the front part of the projectile but also by the shock-wave destruction of rear part of the projectile. The latter is the mechanism, which is inherent to a high-velocity impact on continuous bumpers. Which of these mechanisms prevails depends on the κ and ɛ parameters values. Frontal fragmentation dominates if the bumper has higher aperture of cells while at lower aperture the part of the projectile mass fragmented due to the formation of the jets diminishes significantly and the shock-wave destruction of projectile prevails. Numerical modelling also explains the mechanism of the formation of craters groups linearly distributed over the witness surface which were observed in the earlier experiments on projectile fragmentation upon the mesh bumpers. In addition, experiments on the high-velocity interaction of an aluminium projectile with two spaced string bumpers were carried out in case when the aperture of the string cell exceeded the projectile radius. Despite the lower areal density and small inter-bumper distance, the successive string bumpers revealed extremely higher ability to break up the projectile. Intensive fragmentation occurred even in the range of velocities that was lower than a threshold velocity at which the fragmentation of the projectile would have begun on a continuous aluminum bumper with the equal areal density. Numerical modelling makes clear the mechanics of the interaction of the projectile with the spaced string bumpers of the higher aperture.

Energetics and conserved quantity of an axially moving string undergoing three-dimensional nonlinear vibration

Nonlinear three-dimensional vibration of axially moving strings is investigated in the view of energetics. The governing equation is derived from the Eulerian equation of motion of a continuum for axially accelerating strings. The time-rate of the total mechanical energy associated with the vibration is calculated for the string with its ends moving in a prescribed way. For a string moving in a constant axial speed and constrained by two fixed ends, a conserved quantity is proved to remain unchanged during three-dimensional vibration, while the string energy is not conserved. An approximate conserved quantity is derived from the conserved quantity in the neighborhood of the straight equilibrium configuration. The approximate conserved quantity is applied to verify the Lyapunov stability of the straight equilibrium configuration. Numerical simulations are performed for a rubber string and a steel string. The results demonstrate the variation of the total mechanical energy and the invariance of the conserved quantity.

Two nonlinear models of a transversely vibrating string

Modeling transverse vibration of nonlinear strings is investigated via numerical solutions of partial-differential equations and an integro-partial-differential equation. By averaging the tension along the deflected string, the classic nonlinear model of a transversely vibrating string, Kirchhoff’s equation, is derived from another nonlinear model, a partial-differential equation. The partial-differential equation is obtained via neglecting longitudinal terms in a governing equation for coupled planar vibration. The finite difference schemes are developed to solve numerically those equations. An index is proposed to compare the transverse responses calculated from the two models with the transverse component calculated from the coupled equation. A steel string and a rubber string are treated as examples to demonstrate the differences between the two models of transverse vibration and their deviation from the full model of coupled vibration. The numerical results indicate that the differences increase with the amplitude of vibration. Both models yield satisfactory results of almost the same precision for vibration of small amplitudes. For large amplitudes, the Kirchhoff equation gives better results.

Investigation of service failures of steel music wire

An investigation of a number of service failures of the hard steel strings of plucked musical instruments is reported. All the failed strings were found to contain transverse fatigue cracks, mostly located near the end of the vibrating length (e.g. at the “bridge” of the instrument) and extending to about one third of the section thickness. One wire had corroded severely before failing in fatigue. Final failure occurred by ductile fracture. An analysis of the service stresses showed that the strings are subjected to high mean tensile stresses resulting principally from elastoplastic bending opposite the failure location. It is shown that a small cyclic axial tension arises from repeated plucking during playing and this can lead to fatigue initiation and propagation over a large proportion of the wire cross section. Neither surface nor bulk defects, wear nor contact stresses were found to be factors of importance in the cases examined, contrary to some speculation.

アラミド繊維補強を用いた木造HPシェルと鉄骨張弦梁によるハイブリッド構造の設計(その1) : 山寺郵便局の構造デザインとその展開(構造)

The research and development of hybrid structures cannot be referred as one with sufficiently actual results. In this report we suggested the wooden HP shells made by lumbers of two layers by which the direction lies at right angles with the lugscrew bolt. Here, an aramid fiber sheet is introduced into four wooden HP shells so that the intensity and rigidity of the shells are strengthened. This hybrid structure further combined with steel string beam structure is applied to Yamadera Post Office in Yamagata Prefecture.

The dynamics of musical strings

The resonance contours of a number of musical strings have been traced when operating in isolation from an instrument body, with more precisely defined loading and terminal conditions than are found in normal use, and with very small excitation amplitudes. For plain steel piano strings, results from the fundamental to the 25th overtone are broadly in accordance with the predictions of the standard classical theory for a lossy stiff string, but close agreement with calculated data cannot be obtained for any one set of the relevant parameters, and some disturbing influences are clearly in operation. Some of the resonances show double peaks suggestive of close coupling between slightly dissimilar modes, and for these and the single peaks, associated transverse resonances perpendicular to the line of the driving force are often found. A copper wire string hammered to produce an exaggerated linear distribution of deformation shows a more pronounced pattern of double and transverse resonances, and it is surmised that these occurrences with the steel strings are due to small departures from exact cylindrical uniformity. Overwound strings show similar anomalies with significantly higher losses.

Vibrational modes of a baritone guitar

This work studied the principal modes of vibration of a baritone guitar with steel strings tuned to A1, D2, G2, C3, E3, and A3, a fifth below those of the usual folk guitar. Likewise, the corresponding resonances are designed to be a fifth below those of a steel‐string folk guitar [R. E. Ross and T. D. Rossing, J. Acoust. Soc. Am. 65, S72 (1979)]. The modal shapes have been determined by scanning the plates with an accelerometer and also by scanning the nearfield sound with a probe microphone. Sound radiation fields in an anechoic room for several of the modes are also shown.

Acoustic radiation generated by local excitation of submerged beams and strings

Free and forced motions of submerged one-dimensional waveguides have been investigated. Both the submerged beam and the submerged string can support a wave system which includes a pure surface wave in the fluid adjoining the waveguide, provided that certain conditions on the frequency (for the beam) or the physical parameters of the system (for the string) are satisfied. Dispersion curves are presented for steel beams and steel strings in water. Steady-state solutions have been derived for excitation by a concentrated time-harmonic load. The displacement responses at the point of application of the load and in the far field have been examined. Polar plots display and radiated far field in the fluid. At low frequencies the polar plots are circular in planes containing the waveguide, but the radiation pattern develops lobes as the frequency increases. Reflection, transmission and scattering into the fluid of an incident wave system by an elastic support of stiffness κ and mass m have also been examined, and the possibility of resonance phenomena has been investigated.

Characterizing guitar sound using time-evolving spectra

The sound of a guitar or similar instrument can be characterized by the time evolution of its partials and its noiselike sound components. This includes the establishment or generation of noise, families of partials, and formants and resonances by the nature of the plucking and the characteristics of the instrument. It particularly includes the decay and interchange of energy among all the sound components. The investigation of these components is facilitated by using linear and logarithmic-frequency spectral analysis and by using variable-length time windows in acquiring data to be analyzed. Displays of time-evolving spectra demonstrate the different characteristics of classes of guitars such as classical and steel string and the differences between members of each class. The relationships among measurable sound parameters and guitar quality and guitar design and construction will be discussed.

Stereophonic electromagnetic pickup device for stringed musical instruments

An electric guitar with steel strings feeds into a stereophonic amplifier and loudspeaker system with two channels and is fitted with a pickup which senses each guitar string individually and proportions the signals from each string differently, so that each guitar string sounds from the loudspeakers as though that string is in a different position from all the other strings. For each guitar string the pickup has a respective pair of coils of varying numbers of turns and a respective permanent magnet. Electrical connections to the coils enable one channel to receive a signal from one coil of each pair and the other channel to receive a signal from the other coil of each pair, so that there are two composite signals, one per channel.

High asymmetry variable reluctance pickup system for steel string musical instruments

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Single face, high asymmetry variable reluctance pickup for steel string musical instruments

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Normal Vibration Modes of Stiff Strings

This paper compares the theoretical and experimental behavior of a stiff steel string vibrating under clamped boundary conditions. It is shown that the normal vibration modes of the stiff string are governed by one string constant only. The studies have been extended into a range where the standard formulas for the natural frequencies are not valid. Therefore, computations have been performed from more general relations developed here. Precise criteria are stated for the accuracy obtained. Apparatus has been developed that makes it possible to attain clamped boundary conditions and allow a measurement accuracy to about 0.1%. The experimental results observed with this arrangement are in excellent agreement with the calculated data (the mean-square deviations are below 0.15%).

Inharmonicity of Plain Wire Piano Strings

The inharmonicity of plain wire strings in situ has been measured in six pianos of various styles and makes. By inharmonicity is meant the departure in frequency from the harmonic modes of vibration expected of an ideal flexible string. It is shown from the theory of stiff strings that the basic inharmonicity cents (hundredths of a semitone) is given by 3.4×1013n2d2/v02l4, where n is the mode number, d is the diameter of the wire in cm, l is the vibrating length in cm, and v0 is the fundamental frequency. A value of Q/ρ = 25.5 × 1010 (cm/sec)2 was assumed for the steel wire, where Q is Young's modulus and ρ is the density. The observations are entirely compatible with the relationship given. In general terms the inharmonicity of the plain steel strings is about the same in all the pianos tested, being about 1.2 cents for the second mode of vibration of the middle C string. Above this point every eight semitones it is doubled. Below middle C the inharmonicity is consistently less in large pianos than in small ones.

Inharmonicity of Plain Wire Piano Strings

The inharmonicity of plain wire strings in situ has been measured in six pianos of various styles and makes. By inharmonicity is meant the departure in frequency from the harmonic modes of vibration expected of an ideal flexible string. It is shown from the theory of stiff strings that the basic inharmonicity in cents (hundredths of a semitone) is given by 3.4 × 1013n2d2/ν02l4, where n is the mode number, d is the diameter of the wire in cm, l is the vibrating length in cm, and ν0 is the fundamental frequency. A value of Q/ρ = 25.5 × 10 10 (cm/sec)2 was assumed for the steel wire, where Q is Young's modulus and ρ is the density. The observations are entirely compatible with the relationship given. In general terms, the inharmonicity of the plain steel strings is roughly the same in all the pianos tested, being about 1.2 cents for the second mode of vibration of the middle C string. Above this point, every eight semitones it is doubled. Below middle C the inharmonicity is consistently less in large pianos than in small ones.

Cross-sectional Radiography of the Heart

AROENTGENOLOGIC visualization of the heart, in such a manner as to give a radiologic equivalent to its anatomical cross-section, has been an old problem in cardiac roentgenology. This problem has been approached repeatedly in the past. The several available solutions are, however, complicated, time-consuming, not very exact, and require additional expensive equipment. The underlying principle for all these methods is based on the 360° rotation of the patient around his vertical axis with the recording of the heart borders in different diameters. In this manner, the cross-section can be reconstructed. Some authors go beyond this and produce three-dimensional models of the heart. Palmieri (4), in a very elaborate manner, cuts cardboard silhouettes of many different heart diameters and in setting them together completes the heart model. Lysholm (3) designed an ingenious arrangement permitting direct cutting of a three-dimensional heart model from clay. A rotating chair for the patient is connected with a rotating stand for the clay and an exact correlation with their degree of rotation is maintained. A narrow beam around the central ray is moved under fluoroscopic control along the heart borders. A steel string, mechanically connected with the tube, automatically cuts through the clay so that an approximate model of the heart is fashioned after cutting several diameters. This method was later revived by Schatzki (5). Klason (2) devised an attachment by which an electric rod mechanically follows the movements of the central ray controlled by the fluoroscopist and produces strip-like exposures on photographic paper as desired. He thus obtains a number of lines which produce an approximate outline of a cross-section through the heart. A similar principle for drawing under fluoroscopy or indirectly, after exposing several film strips at different angles, was recently published in this country by Szabados (6). (See Fig. 1.) All these methods, unfortunately, take considerable time, and any motion of the patient during the long examination greatly endangers the accuracy of the measurements. It is, furthermore, not possible to record fine details of the heart contour. Were a direct, instantaneous exposure of the cross-section of the heart possible, its superiority over the indirect methods described above would be apparent. The purpose of this study is to present such a roentgenologic possibility for a direct cross-section radiography of the heart using a fundamentally different projection from those commonly accepted. This study is limited only to its theoretic principles and roentgen-technical factors. The roentgen-clinical aspects of this method will be summarized in a later study. The principle underlying this technic is easily understood (Figs. 2 and 3). On examining a lateral view of the chest, we note that the long axis of the heart—its diagonal diameter—forms an angle averaging from 45 to 50 degrees with the longitudinal diameter of the thorax.