Research data supporting 'Effects of Twisting and Surface Finish on the Mechanical Properties of Natural Gut Harp Strings'

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Lynch_Aird, Nicolas 
Woodhouse, James 

The effects of varying the twist angle and surface finishing on the mechanical properties of gut harp strings have been explored. Strings were tested over a range of twist angles from 23.5° to 58.3°, and with all four combinations of ground or unground and varnished or unvarnished surface finishing. The principal effects of varying the degree of twisting were that the breaking strength and tensile Young's modulus both fell as the twist angle was increased. Leaving the string unvarnished dramatically increased the sensitivity to changes in humidity which in turn affected the thermal tuning sensitivity and creep behaviour. Grinding the string surface prior to varnishing had no significant effect on the behaviour, but did make some difference to the thermal tuning sensitivity if the string was left unvarnished. Increasing the humidity frequently triggered episodes of additional string creep. There appeared to be a threshold effect, with the additional creep triggered when the string linear density exceeded its previous maximum. When the string was not creeping, there appeared to be a strong coupling mechanism between changes in the linear density and complementary changes in the string tension, such that there was almost no net effect on the string frequency. This behaviour was independent of the twist angle and the surface finishing, suggesting that whatever the coupling mechanism was, it was not dependent on the twisted structure of the string. This work builds on the studies reported in and

This dataset contains the raw test data files; detailed test logs describing the different tests; and spreadsheets containing extracted parameter values. The Python scripts used for processing the measured data and plotting graphs of the extracted parameters are included. These scripts were written using Jupyter Notebooks. HTML exports of the scripts are also provided. As well as the data for the twist angle and surface finish studies, the data set also contains the results of various breaking strength tests, and details of the test rigs and control software used. More details are given in the README.txt files, and further details regarding the test rigs can be found at and

Software / Usage instructions
Requirements: PDF reader, spreadsheet, Python implementation to use the Python code
Harp string, Mechanical properties, Natural gut