Design and development of a low-cost two-point bending tester for bamboo culm sheaths

Indraswari Kusumaningtyas; Jalu Akbar Wirabuana; Al Hafid Baharsyah; Gea Oswah Fatah Parikesit

doi:10.71452/y4ket639

Authors

Indraswari Kusumaningtyas Departemen Teknik Mesin dan Industri Fakultas Teknik Universitas Gadjah Mada Author
Jalu Akbar Wirabuana Author
Al Hafid Baharsyah Author
Gea Oswah Fatah Parikesit Departemen Teknik Nuklir dan Teknik Fisika, Fakultas Teknik, Universitas Gadjah Mada Author

DOI:

https://doi.org/10.71452/y4ket639

Keywords:

bamboo culm sheath, modulus of elasticity, two-point bending, design, prototype

Abstract

Sound generation in musical instruments depends on the instrument’s material properties. This is not yet completely understood for the bundengan musical instrument because the material properties of the bamboo culm sheath (slumpring in Javanese) that covers the bundengan’s woven structure are unknown. The dominant vibration mode of the bundengan is transversal; thus, the bending modulus of elasticity is required. Bamboo culm sheaths are thin, lightweight, and relatively fragile, so they must be characterised by a bending tester that can deliver a small enough force at a constant deflection rate. This is essential to obtain sufficient data within the material’s elastic region before the bamboo culm sheath breaks. It was observed that there are similarities between the structure of bamboo culm sheaths and corrugated paperboard. Therefore, a two-point bending tester was designed and developed based on the bending test standards of paper and paperboard. The design process comprises needs identification, design specification, and conceptual, preliminary, and detailed design. A prototype was then developed, calibrated, and tested. Tests with specimens made from thin aluminium plates gave a bending modulus of 75.15±5.90 GPa and 74.59±2.55 GPa for deflection angles of 5.4° and 15.3°, respectively. This indicates that the two-point bending tester can perform repeated tests with relatively good precision and accuracy, so that it can be further used to test bamboo culm sheaths.

References

T.D. Rossing, N.H. Fletcher, The Physics of Musical Instruments. 2nd ed., New York: Springer Science and Business Media New York, 1998.

J. Kunst, Music in Java: Its history, Its Theory and Its Technique. 2nd ed., Dordrecht: Springer, 1949.

G.O.F. Parikesit, I. Kusumaningtyas, The illusive sound of a bundengan string. Physics Education, 52(5), 055007, 2017. https://doi.org/10.1088/1361-6552/aa7f09

G.O.F. Parikesit, I. Kusumaningtyas, Vibration of clipped strings in the bundengan musical instrument. Applied Acoustics, 155(1), 204-215, 2019. https://doi.org/10.1016/j.apacoust.2019.06.011

I. Kusumaningtyas, G.O.F. Parikesit, Computational analysis of the bundengan, an endangered musical instrument from Indonesia. Proceedings of Meetings on Acoustics, 33(1), 035001, 2018. https://doi.org/10.1121/2.0000800

I. Kusumaningtyas, A.F. Sedjati, A.J. Hifzhuddin, G.O.F. Parikesit, The effect of bamboo clip dimension and position towards the frequency spectrum of a vibrating inhomogeneous bundengan string. Proceedings of InterNoise21, Washington, D.C., U.S.A., 2021.

G.O.F. Parikesit, A modified Mersenne law governs the inter-mode patterns in bundengan string vibrations. Proceedings of Meetings on Acoustics, 43(1), 035001, 2021. https://doi.org/10.1121/2.0001440

G.O.F. Parikesit, I.E. Pratama, I. Kusumaningtyas, How the string ends affect the bundengan string vibrations. Proceedings of the 28th International Congress on Sound and Vibration, Singapore, 2022.

G.O.F. Parikesit, F. Aulia, I. Kusumaningtyas, How the bundengan string material affects its musical sound. Proceedings of InterNoise23, Chiba, Greater Tokyo, Japan, 2023.

G.O.F. Parikesit, A. Pratama, I. Kusumaningtyas, Vibrational analysis of the bundengan bamboo bars. Proceedings of the 28th International Congress on Sound and Vibration, Singapore, 2022.

G.O.F. Parikesit, Why the bundengan is a personal musical instrument. Proceedings of InterNoise20, Seoul, South Korea, 2020.

G.O.F. Parikesit, I. Kusumaningtyas, Quantitative analysis of the kowangan resonator. Proceedings of Meetings on Acoustics, 42(1), 035002, 2020. https://doi.org/10.1121/2.0001340

I. Kusumaningtyas, R. Christianto, G.O.F. Parikesit, Sound directional characteristics of the bundengan musical instrument. Proceedings of Meetings on Acoustics, 42(1), 035008, 2020. https://doi.org/10.1121/2.0001416

G.O.F. Parikesit, L.C. Simanungkalit, I. Kusumaningtyas, Experimental modal analysis of the kowangan resonator in the bundengan musical instrument. Proceedings of the 28th International Congress on Sound and Vibration, Singapore, 2022.

U.G.K. Wegst, Bamboo and wood in musical instruments. Annual Review of Materials Research, 38, 323-349, 2008.

Nurmadina, N. Naresworo, E.T. Bachtiar, Structural grading of Gigantochloa apus bamboo based of its flexural properties. Construction and Building Materials, 157, 1173–1189, 2017.

G.O.F. Parikesit, I. Kusumaningtyas, Why bundengan musicians always soak their instruments before playing. Proceedings of Meetings on Acoustics, 52(1), 035010, 2023. https://doi.org/10.1121/2.0001888

Y. Ahmad, I. Kusumaningtyas, G.O.F. Parikesit, Studi sifat keterbasahan pada material slumpring bambu dengan metode pengukuran sudut kontak permukaan. Journal of Mechanical Design and Testing, 6(1), 1-9, 2024.