FEASIBILITY STUDY ON THE USE OF SILICON-BRONZE ALLOY AS AN ALTERNATIVE MATERIAL FOR BALINESE FEASIBILITY STUDY ON THE USE OF SILICON-BRONZE ALLOY AS AN ALTERNATIVE MATERIAL FOR BALINESE MUSICA.
I Made Miasa
!"
#
$
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& &
I Ketut Gede Sugita
'
This research was carried out to investigate the acoustics feasibility of using silicon bronze
(( # )* ) alloy to replace tin bronze (( # +)* ) alloy for Balinese traditional musical
instruments. This research is the next step of the previous research that has sucessfully
showed better mechanical properties of ( #* alloy compared to ( #* alloy. The acoustical
properties of interest in this study are: speed of sound ( ), sound radiation coefficient (,) and
frequency resistance ( & & frequency’s shift). The casted alloys were cut and machined for the
test specimens. The acoustical properties of both alloys were measured and compared. The
investigations were carried out according to ASTM Standard E 1876 01. For frequency shift
investigation, the original fundamental frequency of each alloy is measured and then each
alloy is subjected to impact load by hitting them as they are played in daily use. The total
number of cycles (hits) experienced by each alloy is 72,000. Finally the resulting
fundamental frequency is measured and compared to the previous (before hitting) conditions.
The frequencies were measured after a certain interval numbers of hit until total of 72,000
hits. The results showed that ( #* alloy has speed of sound ( ) and sound radiation
coefficient (,) that are almost the same as those of ( #* alloy. For frequency’s shift, both
alloy showed that they do not experience any frequency change after 72,000 hits. This is a
good sign showing the potential of silicon bronze alloy as an alternative material for Balinese
musical instruments replacing tin bronze alloy currently used.
Bronze is a metal alloy primarily made of copper (( ), usually with tin (* ) as the main
additive. This alloy is one of the oldest alloys known to human civilization. Bronze is often called
tin bronze because its main components are copper and tin. Tin bronze is widely used for machine
elements such as bearings, pump vanes, piston rings, bells, gears, etc. Compared to pure copper and
brass, bronze is an alloy which is easily casted and formed.
ICSV20, Bangkok, Thailand, 7 11 July 2013
1
20th International Congress on Sound and Vibration (ICSV20), Bangkok, Thailand, 7 11 July 2013
The high tin bronze alloy with composition of 18 22 wt. % * has good acoustical properties
which is capable of producing long lasting sound due to its low vibration damping 1,2. It is
commonly used for music instrument materials such as bell, Javanese and Balinese gamelan. This is
a double phase alloy containing brittle particles of ( -"* ! intermetallic (δ phase), which is harder
and more brittle than other alloys. However, the main disadvantages of high tin bronze properties
are: it has a low crack resistance (it cracks easily), it is brittle and expensive. Moreover, tin bronze
cannot resist low temperature because it has a low frost resistance. At temperature below minus (20
to 25)oC this alloy becomes brittle and cracks may appear resulted in poor sound quality3.
Meanwhile silicon bronze is an alloy that has good cast ability and higher mechanical properties
than tin bronzes. In addition, the silicon bronze has high elastic properties, possesses a higher cor
rosion resistance than a tin bronze, does not lose its properties at low temperatures and it is cheaper
than tin bronze4,5. Therefore, based on the abovementioned facts, this study was carried out to in
vestigate the feasibility of silicon bronze alloy as a subtitute of tin bronze alloy used for music in
strument materials.
!"# $# %& "
#
#
% # %&' % "
#''
This study was started with the preparation of raw materials that will be casted such as copper
(( ), tin (* ) and silicon (* ). The composition of copper and tin for tin bronze alloys and the com
position of copper and silicon for silicon bronze alloys were designed in accordance with the results
of the authors’ previous studies 6,7. The alloys under investigation were made of ( # )* and ( #
+)* . The composition of the alloy studied in this research is listed in Table 1. The acoustics
properties comparisons were made with respect to ( # +)* as the reference alloy because it is
commonly used for making bells or gamelans. The commercial pure copper and commercial pure
silicon were melted in crucible furnace at temperature of 1000oC. The resulting casted billets were
cut and finished for acoustical test specimens. In this investigation three pieces of elements were
prepared for each alloy, so that in total there are 6 specimens.
Composition of the alloys.
Bronze
alloys
( # +*
( # *
(. %.)
(
*
*
/0
79.18 19.1
1.18
93.55 0.427 4.73 0.696
1
0.505
0.427
*
2
0.001 0.014 0.055
0.002 0.046 0.004
#%' #$# ' %
%& &%
'
The acoustical properties of interest in this study are: speed of sound ( ), sound radiation
coefficient (,) and frequency resistance ( & & frequency’s shift). The acoustical properties of both
alloys were measured and compared. The investigations were carried out according to ASTM
Standard E 1876 018, and the lay out of the measurement is depicted in Fig.1.
. Set–up of fundamental frequency measurement.
ICSV20, Bangkok, Thailand, 7 11 July 2013
2
20th International Congress on Sound and Vibration (ICSV20), Bangkok, Thailand, 7 11 July 2013
For frequency shift investigation, the original fundamental frequency of each alloy is meas
ured and then each alloy is subjected to impact load by hitting them such as when they are played in
daily use. The total number of cycles (hits) experienced by each alloy is 72,000. Finally the result
ing fundamental frequency is measured and compared to the previous (before hitting) conditions.
The frequencies were measured after a certain interval numbers of hit until total of 72,000 hits. Fig
ure 2 shows the experimental set up for frequency resistance tests.
. Set–up for frequency resistance measurement.
From the measurements of fundamental frequency based on ASTM Standard E 1876 01, the
Young’s modulus ( ) can be calculated from
(Pa)
(1)
where:
= Young’s modulus [Pa]
= mass of the bar [gr]
0 = width of the bar [mm]
3= length of the bar [mm]
= thickness of the bar [mm]
= fundamental resonant frequency of the bar in flexure [Hz]
4" = correction factor, in this case it has a value of
!
".
(2)
As one of the acoustics properties of interest in this study, the speed of sound traveling
through material ( ) is then calculated using the following formula
#
$
% (m/s)
where % is the measured density of the specimen.
(3)
The sound radiation coefficient , describes how much the vibration of the body is damped
due to sound radiation9. It can also be regarded as an index of the amplitude of vibration that a ma
terial will sustain for a given excitation force (a dynamic property) combined with a measure of its
stiffness for a given mass (a static property)10. Particularly, a large sound radiation coefficient is
preferred if a loud sound is desired. The sound radiation coefficient can be calculated from9
&
$
4
%' (m .kg/s) .
ICSV20, Bangkok, Thailand, 7 11 July 2013
(4)
3
20th International Congress on Sound and Vibration (ICSV20), Bangkok, Thailand, 7 11 July 2013
(
#' & ' %
'
''
'
(
%$# %& % ') * * #+ # #'
Figure 3a and 3b show the fundamental frequencies of the specimens for both ( # +)* and
( # )* alloys respectively. As can be seen, for both alloys, the first three modes appeared. The
fundamental one is used to calculate the Young’s Modulus ( ) using Eq. (1) and then the remaining
and , are calculated from Eq. (3) and Eq. (4).
.Fundamental resonant frequency of the bar in flexure
The frequency resistance which describes the resistance of the material with respect to the
shift of frequency after being hit for certain numbers of cycles is depicted in Fig. 4 below. In addi
tion to the “untreated” ( # +)* and ( # )* alloys, the results from ( # +)* alloy with prior
forging treatment (bar #7 9) were also presented in Fig. 4.
' 1, 2 and 3 are ( # )*
' 4, 5 and 6 are ( # +)*
' 7, 8 and 9 are ( # +)*
with
. Frequency resistance test results
(
' %& " "# #'
From the measurements and calculations above, the speed of sound , the sound radiation
coefficient , and the frequency resistance of all alloys are tabulated in Table 2.
ICSV20, Bangkok, Thailand, 7 11 July 2013
4
20th International Congress on Sound and Vibration (ICSV20), Bangkok, Thailand, 7 11 July 2013
. Acoustical properties of bronze alloys
, (m4/kg.s)
Alloys
(m/s)
1.
( # +*
3398.4
0.393
2.
( # *
3380.4
0.407
No.
Frequency
Resistance
Stable
5
6
Stable
5
6
7
7
It can be seen from Fig. 4 that most of the frequencies of the bars (Bilah # 1 6) measured af
ter a certain number of cycles remain unchanged (constant). No frequency shift indicates that the
bar will not detune (lost its tune) easily so that a good sound quality can be maintained. An interest
ing phenomenon was observed for ( #* alloys that experienced forging process after casting and
cutting. These alloys easily change their frequencies, and in this study frequency shifts up to 6 Hz
were observed. It seems that the forging process that is currently applied for these alloys tends to
deteriorate their acoustics properties as indicated by the frequency shift. Furthermore, Table 2
showed that that ( #* alloy has a speed of sound ( ) and a sound radiation coefficient (,) that are
almost the same as those of ( #* alloy.
,
& '
Based on the results of this study, it can be concluded that ( #* alloy with a proper composi
tion can become a potential material to substitute the currently used ( #* alloy while maintaining
its sound quality.
1
2
3
4
5
6
7
8
9
10
Scott, D.A., 1991,
2
8
, The
Getty Conservation Institute.
Hosford, F.W., 2005,
'
, Cambridge University Press.
Favstov, Y. K., Zhravel, L.V. andKochetkova, L.P., Structure and Damping Capacity of
Br022 Bell Bronze, 9
*
8 4
,
, pp. 449 451, (2003.)
Lisovskii, V. A., Lisovskaya. O. B, Kochetkova, L. P. andFavstov, Y. K., Sparingly Alloyed
Bell Bronze with Elevated Parameters of Mechanical Properties, 9
*
8 4
,
, pp. 232 235, (2007).
Smith, F.W., 1993, *
, Second Edition, McGraw
Hill Inc.
I KetutGede Sugita, R. Soekrisno, I Made Miasa and Suyitno, Mechanical and damping prop
erties of silicon bronze alloys for music applications,
9
:
4
9 4# 9 ;*
, No. 6, (2011).
I KetutGede Sugita, R. Soekrisno, I Made Miasa and Suyitno, The effect of annealing temper
ature on damping capacity of the bronze 20%Sn alloy
9
:
9
< 9 ;*
, No. 4, 2011
ASTM, E 1876 01, 2002, *
4
*
=
/
,
0
>
?0
, ASTM International.
Wegst, U.G.K, Wood for Sound, 2
9
'
,
, 1439–1448, 2006.
Trevor Gore Guitars, 2012, @
8
[Online], available :
http://www.goreguitars.com.au/main/page_about_design_sound_rad_coeff.html
ICSV20, Bangkok, Thailand, 7 11 July 2013
5
!"
#
$
%
& &
I Ketut Gede Sugita
'
This research was carried out to investigate the acoustics feasibility of using silicon bronze
(( # )* ) alloy to replace tin bronze (( # +)* ) alloy for Balinese traditional musical
instruments. This research is the next step of the previous research that has sucessfully
showed better mechanical properties of ( #* alloy compared to ( #* alloy. The acoustical
properties of interest in this study are: speed of sound ( ), sound radiation coefficient (,) and
frequency resistance ( & & frequency’s shift). The casted alloys were cut and machined for the
test specimens. The acoustical properties of both alloys were measured and compared. The
investigations were carried out according to ASTM Standard E 1876 01. For frequency shift
investigation, the original fundamental frequency of each alloy is measured and then each
alloy is subjected to impact load by hitting them as they are played in daily use. The total
number of cycles (hits) experienced by each alloy is 72,000. Finally the resulting
fundamental frequency is measured and compared to the previous (before hitting) conditions.
The frequencies were measured after a certain interval numbers of hit until total of 72,000
hits. The results showed that ( #* alloy has speed of sound ( ) and sound radiation
coefficient (,) that are almost the same as those of ( #* alloy. For frequency’s shift, both
alloy showed that they do not experience any frequency change after 72,000 hits. This is a
good sign showing the potential of silicon bronze alloy as an alternative material for Balinese
musical instruments replacing tin bronze alloy currently used.
Bronze is a metal alloy primarily made of copper (( ), usually with tin (* ) as the main
additive. This alloy is one of the oldest alloys known to human civilization. Bronze is often called
tin bronze because its main components are copper and tin. Tin bronze is widely used for machine
elements such as bearings, pump vanes, piston rings, bells, gears, etc. Compared to pure copper and
brass, bronze is an alloy which is easily casted and formed.
ICSV20, Bangkok, Thailand, 7 11 July 2013
1
20th International Congress on Sound and Vibration (ICSV20), Bangkok, Thailand, 7 11 July 2013
The high tin bronze alloy with composition of 18 22 wt. % * has good acoustical properties
which is capable of producing long lasting sound due to its low vibration damping 1,2. It is
commonly used for music instrument materials such as bell, Javanese and Balinese gamelan. This is
a double phase alloy containing brittle particles of ( -"* ! intermetallic (δ phase), which is harder
and more brittle than other alloys. However, the main disadvantages of high tin bronze properties
are: it has a low crack resistance (it cracks easily), it is brittle and expensive. Moreover, tin bronze
cannot resist low temperature because it has a low frost resistance. At temperature below minus (20
to 25)oC this alloy becomes brittle and cracks may appear resulted in poor sound quality3.
Meanwhile silicon bronze is an alloy that has good cast ability and higher mechanical properties
than tin bronzes. In addition, the silicon bronze has high elastic properties, possesses a higher cor
rosion resistance than a tin bronze, does not lose its properties at low temperatures and it is cheaper
than tin bronze4,5. Therefore, based on the abovementioned facts, this study was carried out to in
vestigate the feasibility of silicon bronze alloy as a subtitute of tin bronze alloy used for music in
strument materials.
!"# $# %& "
#
#
% # %&' % "
#''
This study was started with the preparation of raw materials that will be casted such as copper
(( ), tin (* ) and silicon (* ). The composition of copper and tin for tin bronze alloys and the com
position of copper and silicon for silicon bronze alloys were designed in accordance with the results
of the authors’ previous studies 6,7. The alloys under investigation were made of ( # )* and ( #
+)* . The composition of the alloy studied in this research is listed in Table 1. The acoustics
properties comparisons were made with respect to ( # +)* as the reference alloy because it is
commonly used for making bells or gamelans. The commercial pure copper and commercial pure
silicon were melted in crucible furnace at temperature of 1000oC. The resulting casted billets were
cut and finished for acoustical test specimens. In this investigation three pieces of elements were
prepared for each alloy, so that in total there are 6 specimens.
Composition of the alloys.
Bronze
alloys
( # +*
( # *
(. %.)
(
*
*
/0
79.18 19.1
1.18
93.55 0.427 4.73 0.696
1
0.505
0.427
*
2
0.001 0.014 0.055
0.002 0.046 0.004
#%' #$# ' %
%& &%
'
The acoustical properties of interest in this study are: speed of sound ( ), sound radiation
coefficient (,) and frequency resistance ( & & frequency’s shift). The acoustical properties of both
alloys were measured and compared. The investigations were carried out according to ASTM
Standard E 1876 018, and the lay out of the measurement is depicted in Fig.1.
. Set–up of fundamental frequency measurement.
ICSV20, Bangkok, Thailand, 7 11 July 2013
2
20th International Congress on Sound and Vibration (ICSV20), Bangkok, Thailand, 7 11 July 2013
For frequency shift investigation, the original fundamental frequency of each alloy is meas
ured and then each alloy is subjected to impact load by hitting them such as when they are played in
daily use. The total number of cycles (hits) experienced by each alloy is 72,000. Finally the result
ing fundamental frequency is measured and compared to the previous (before hitting) conditions.
The frequencies were measured after a certain interval numbers of hit until total of 72,000 hits. Fig
ure 2 shows the experimental set up for frequency resistance tests.
. Set–up for frequency resistance measurement.
From the measurements of fundamental frequency based on ASTM Standard E 1876 01, the
Young’s modulus ( ) can be calculated from
(Pa)
(1)
where:
= Young’s modulus [Pa]
= mass of the bar [gr]
0 = width of the bar [mm]
3= length of the bar [mm]
= thickness of the bar [mm]
= fundamental resonant frequency of the bar in flexure [Hz]
4" = correction factor, in this case it has a value of
!
".
(2)
As one of the acoustics properties of interest in this study, the speed of sound traveling
through material ( ) is then calculated using the following formula
#
$
% (m/s)
where % is the measured density of the specimen.
(3)
The sound radiation coefficient , describes how much the vibration of the body is damped
due to sound radiation9. It can also be regarded as an index of the amplitude of vibration that a ma
terial will sustain for a given excitation force (a dynamic property) combined with a measure of its
stiffness for a given mass (a static property)10. Particularly, a large sound radiation coefficient is
preferred if a loud sound is desired. The sound radiation coefficient can be calculated from9
&
$
4
%' (m .kg/s) .
ICSV20, Bangkok, Thailand, 7 11 July 2013
(4)
3
20th International Congress on Sound and Vibration (ICSV20), Bangkok, Thailand, 7 11 July 2013
(
#' & ' %
'
''
'
(
%$# %& % ') * * #+ # #'
Figure 3a and 3b show the fundamental frequencies of the specimens for both ( # +)* and
( # )* alloys respectively. As can be seen, for both alloys, the first three modes appeared. The
fundamental one is used to calculate the Young’s Modulus ( ) using Eq. (1) and then the remaining
and , are calculated from Eq. (3) and Eq. (4).
.Fundamental resonant frequency of the bar in flexure
The frequency resistance which describes the resistance of the material with respect to the
shift of frequency after being hit for certain numbers of cycles is depicted in Fig. 4 below. In addi
tion to the “untreated” ( # +)* and ( # )* alloys, the results from ( # +)* alloy with prior
forging treatment (bar #7 9) were also presented in Fig. 4.
' 1, 2 and 3 are ( # )*
' 4, 5 and 6 are ( # +)*
' 7, 8 and 9 are ( # +)*
with
. Frequency resistance test results
(
' %& " "# #'
From the measurements and calculations above, the speed of sound , the sound radiation
coefficient , and the frequency resistance of all alloys are tabulated in Table 2.
ICSV20, Bangkok, Thailand, 7 11 July 2013
4
20th International Congress on Sound and Vibration (ICSV20), Bangkok, Thailand, 7 11 July 2013
. Acoustical properties of bronze alloys
, (m4/kg.s)
Alloys
(m/s)
1.
( # +*
3398.4
0.393
2.
( # *
3380.4
0.407
No.
Frequency
Resistance
Stable
5
6
Stable
5
6
7
7
It can be seen from Fig. 4 that most of the frequencies of the bars (Bilah # 1 6) measured af
ter a certain number of cycles remain unchanged (constant). No frequency shift indicates that the
bar will not detune (lost its tune) easily so that a good sound quality can be maintained. An interest
ing phenomenon was observed for ( #* alloys that experienced forging process after casting and
cutting. These alloys easily change their frequencies, and in this study frequency shifts up to 6 Hz
were observed. It seems that the forging process that is currently applied for these alloys tends to
deteriorate their acoustics properties as indicated by the frequency shift. Furthermore, Table 2
showed that that ( #* alloy has a speed of sound ( ) and a sound radiation coefficient (,) that are
almost the same as those of ( #* alloy.
,
& '
Based on the results of this study, it can be concluded that ( #* alloy with a proper composi
tion can become a potential material to substitute the currently used ( #* alloy while maintaining
its sound quality.
1
2
3
4
5
6
7
8
9
10
Scott, D.A., 1991,
2
8
, The
Getty Conservation Institute.
Hosford, F.W., 2005,
'
, Cambridge University Press.
Favstov, Y. K., Zhravel, L.V. andKochetkova, L.P., Structure and Damping Capacity of
Br022 Bell Bronze, 9
*
8 4
,
, pp. 449 451, (2003.)
Lisovskii, V. A., Lisovskaya. O. B, Kochetkova, L. P. andFavstov, Y. K., Sparingly Alloyed
Bell Bronze with Elevated Parameters of Mechanical Properties, 9
*
8 4
,
, pp. 232 235, (2007).
Smith, F.W., 1993, *
, Second Edition, McGraw
Hill Inc.
I KetutGede Sugita, R. Soekrisno, I Made Miasa and Suyitno, Mechanical and damping prop
erties of silicon bronze alloys for music applications,
9
:
4
9 4# 9 ;*
, No. 6, (2011).
I KetutGede Sugita, R. Soekrisno, I Made Miasa and Suyitno, The effect of annealing temper
ature on damping capacity of the bronze 20%Sn alloy
9
:
9
< 9 ;*
, No. 4, 2011
ASTM, E 1876 01, 2002, *
4
*
=
/
,
0
>
?0
, ASTM International.
Wegst, U.G.K, Wood for Sound, 2
9
'
,
, 1439–1448, 2006.
Trevor Gore Guitars, 2012, @
8
[Online], available :
http://www.goreguitars.com.au/main/page_about_design_sound_rad_coeff.html
ICSV20, Bangkok, Thailand, 7 11 July 2013
5