Mechanical Properties of Nylon Harp Strings.

Nicolas Lynch-Aird,Jim Woodhouse

doi:10.3390/ma10050497

Nicolas Lynch-Aird, Jim Woodhouse

Open Access

https://doi.org/10.3390/ma10050497

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Abstract

Monofilament nylon strings with a range of diameters, commercially marketed as harp strings, have been tested to establish their long-term mechanical properties. Once a string had settled into a desired stress state, the Young’s modulus was measured by a variety of methods that probe different time-scales. The modulus was found to be a strong function of testing frequency and also a strong function of stress. Strings were also subjected to cyclical variations of temperature, allowing various thermal properties to be measured: the coefficient of linear thermal expansion and the thermal sensitivities of tuning, Young’s modulus and density. The results revealed that the particular strings tested are divided into two groups with very different properties: stress-strain behaviour differing by a factor of two and some parametric sensitivities even having the opposite sign. Within each group, correlation studies allowed simple functional fits to be found to the key properties, which have the potential to be used in automated tuning systems for harp strings.

Highlights

It is well known that the properties of musical instrument strings vary significantly with time, temperature and humidity, requiring players to retune their instruments frequently
Automated string tuning systems have been developed [1,2], but these generally require the instrument to be switched into a specific tuning mode, with the string being plucked or struck in order to generate a tone that can be compared with the required musical pitch
This paper presents some results from an investigation into the mechanical behaviour of nylon harp strings

Summary

Introduction

It is well known that the properties of musical instrument strings vary significantly with time, temperature and humidity, requiring players to retune their instruments frequently. The tuning of nylon and natural gut strings in particular can vary noticeably during the course of a performance. For instruments with a fingerboard, the player can make some correction by changing the effective length of the string being played, but for open string instruments, and the harp in particular, the player can really only wait until the break in the music to retune an errant string. A motor is used to adjust the string tension as necessary. Even if such a system were adapted for use during a performance, it would not help with the situation where the string is already noticeably out of tune when it comes to be played. A tuning system would make pre-emptive adjustments to maintain the string’s pitch while it is not being played

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Conclusion