Zainal Arifin* | Singgih Dwi Prasetyo | Ubaidillah Ubaidillah | Suyitno Suyitno | Dominicus Danardono Dwi Prija Tjahjana | Wibawa Endra Juwana | Rendy Adhi Rachmanto | Aditya Rio Prabowo | Chico Hermanu Brillianto Apribowo
© 2022 IIETA. This article is published by IIETA and is licensed under the CC BY 4.0 license (http://creativecommons.org/licenses/by/4.0/).
OPEN ACCESS
Boccia is one of the fastest-growing Paralympic sports and one of the few sports to have an Olympic rival. The BC3 boccia class is intended for athletes with locomotor dysfunction so severe in all four extremities that they require assistance from assistants and aids in the form of ramps and helmets equipped with pointer sticks. Therefore, the design of the BC3 boccia stick helmet was carried out to meet the needs of the athletes. The design was carried out by action research methodology with the concept of design, static simulation, manufacturing, and the house of quality. The design is divided into three main parts: the helmet bracket, shaft, and lock with bearings using M4 and M8 bolts. Static and design simulations used Fusion 360 and Ansys 2021 R2 software to determine design strength value. Stainless steel material is used in the design, considering the material selection using the Ashby diagram method. The maximum displacement value produced by design is 0.006 mm, and the minimum safety factor is 9.15. The manufacturing results produced helmet products with adequate accuracy and safety standards. A house of quality (HOQ) of 39% indicates that it can meet consumer needs better than other products.
boccia BC3 helmet, design, static stimulation, HOQ
Paralympic sports are competitions for people with physical, mental, and sensorial disabilities. Initially, disability sports were only intended for rehabilitation and recreation. However, over time, sports by people with disabilities have become aimed at achievement, not only rehabilitation and recreation. There have been many competitive Paralympic sports that can be classified according to disability categories. Over the past few years, the Paralympics have gained a high public profile and have received more attention from various parties, who will continue to develop the Paralympic games [1].
Boccia is one of the fastest-growing Paralympic sports and one of the few sports to have an Olympic rival. This sport, regulated by the Boccia International Sports Federation, is a precision sport designed for individuals with cerebral palsy that affects motor skills. According to the World Health Organization (WHO), cerebral palsy (CP) is a chronic, non-progressive brain injury that can occur during the prenatal, perinatal, or first to the fifth year of life and is characterized by motor impairment. Boccia sports are distinguished by the purpose of competition, which depends on the players' physical and functional abilities [2]. Boccia athletes are classified in one of four classes: BC1, BC2, BC3, or BC4. The BC3 athlete class is intended for athletes with very severe locomotor dysfunction in all four extremities; they have no sustained gripping or release motion, and have short range of motion to get the boccia ball onto the court [3]. Therefore, they need some help from assistants and tools in the form of ramps and helmets equipped with pointer sticks, as shown in Figure 1.
The boccia National Paralympic Committee (NPC) in Surakarta has some of the leading boccia athletes who have had various achievements at both national and international levels. Boccia with a BC3 classification is now starting to be developed at the Surakarta NPC in order to represent Indonesia at the ASEAN Para Games (APG) in Vietnam in 2021 and strengthen the Central Java NPC boccia team in order to compete in the 2021 Papua National Paralympic Week (Peparnas). Moreover, it supports boccia to be more successful at national and international levels. Facilities in the form of tools play an important role when used in BC3 class boccia games [3, 4]. In order to support the equipment requirements in the BC3 classification of boccia, NPC Surakarta needs to develop the pointer stick helmet. The boccia helmets available in the market still have a low level of accuracy with athlete safety and comfort standards that have not been met, which can affect the safety and the result of the boccia games. This is because the helmet's function is crucial in the BC3 classification of boccia sports; namely, it helps the athlete direct the ball, roll the ball, and aim at the ball's target direction [5, 6].
A helmet stick is designed to produce a stick helmet product with adequate accuracy and safety standards based on the above explanation. Helmets are specially designed and developed based on the criteria desired by NPC Surakarta.
Figure 1. Boccia Sport Class BC3
The research method used in this study is the action research (AR) method. Action research aims to improve the application of the methods/approaches of practitioners in the appropriate field of science. In addition, this research uses engineering methods, namely carrying out design activities [7]. The design uses numerical methods and application simulation using the Fusion 360 and Ansys 2021 R2 applications.
Based on the concept of design and identification of consumer needs that have been made obtained, benefits such as the value of HOQ products can be achieved correctly, simplification of sketches to create effective and efficient products, and the selection of materials that are more follow the design concept [8]. In general, the research steps are shown in Figure 2.
Figure 2. Research flowchart
2.1 Design concept
The design was made to identify the consumer demand for BC3 boccia sports equipment. The design was developed from an existing design to achieve effective and efficient use. The design idea of this article was developed from affirmative action research by interviewing members of the Surakarta NPC and BC3 boccia Paralympic athletes. Interview results also consider the house of quality (HOQ) assessment. The design is focused on the BC3 boccia helmet stick, which has a vital role in the boccia sport. Thus, the design is concerned with producing a stick helmet product with adequate accuracy and safety standards [2].
2.2 Design
The design is based on the design ideas and identified consumer needs to achieve the correct HOQ value for the product. The initial design was produced by creating an initial sketch using the Fusion 360 application. The sketch was divided into several parts to create an effective and efficient product [9]. On the other hand, the selection of materials to support the sketch was carried out according to the Ashby diagram method, taking into account the existing design concepts.
2.3 Static simulation
Static analysis for the framework of the boccia helmet stick sporting apparatus was carried out by simulating the load on the frame using Fusion 360 software. To increase the validity of the design, static simulations were also carried out using Ansys 2021 R2 software. This was aimed at determining the reliability of the strength and safety factors of the tool [10]. In the static simulation found in Ansys, the numerical method used is the finite element method to determine the deformation that occurs in the design.
In addition, to determine the reliability of the bearings, a bearing safety analysis was carried out using a numerical method. The bearing safety of the bolt connector was based on the tensile stress of the bolt [11]. Furthermore, the safety factor was calculated by [12].
$S_{f}=\frac{\text { yield stress }}{\text { calculated stress }}$ (1)
2.4 Manufacture
Manufacturing planning was conducted to find out how the design development was going. In addition, planning helps decide whether to manufacture or purchase individual parts. This made it easy to analyze the needs of the machines used in production to process each part. Manufacturing was carried out based on the planning conducted [13, 14].
2.5 House of quality (HOQ)
The House of Quality (HoQ) is a popular design tool that supports information processing and decision-making in the engineering design process. While its application is an aid to conceptual aspects of the design process, its use as a quantitative information tool in engineering design is potentially flawed. This Flaw results from potential designer interpretations of HoQ results — invalid interpretations given the assumptions and sources of information behind HoQ — and are seen as critical limitations on method outcomes that can lead to potentially invalid and bad decisions [15].
House of quality (HOQ) delivers high-quality performance to determine the value of a product that consumers expect. HOQ can be used to define design modules, subsystem characteristics, and manufacturing processes for early identification to ensure product quality. This method also allows the properties of the main components to be compared with the primary manufacturing process [9, 11, 16].
3.1 Design concept
The use of sticks on the BC3 boccia helmet is necessary for boccia Paralympic athletes. Helmet sticks propel the ball; thus, a strong and flexible design is required. Helmet stick strength is based on the safety value of the BC3 boccia helmet stick design. The research was conducted by designing a BC3 boccia helmet with a simple design, accessible materials, and ease of operation. The boccia stick helmet uses a ball guide, ball scroller, and ball direction target, which can also be developed to increase accuracy in the game. The initial sketch design concept is as shown in Figure 3(a). Because the ball propulsion shaft is not long enough, which makes it difficult for the boccia athlete to push the boccia ball [2], the improvement of the sketch was carried out as shown in Figure 3(b).
(a) Beginning
(b) Final
Figure 3. Sketch
3.2 Design
After achieving a basic design, a drawing of the tool was carried out using the Fusion 360 software. The drawing was made into three parts: a helmet bracket part, shaft part, and locking part, as shown in Figure 4. This three-part division was to make it easier to assemble the tool. The total design volume is 105350 mm3 with a weight of 0.82 kg.
Figure 4. BC3 boccia helmet stick assembly
The design in Figure 4 shows that the shaft part is indicated by number 2, the locking pin at number 3, and the helmet bracket at number 1. While in other parts, it serves as bearings. The tool size for each part was adjusted to the height and average load. This is so that the tool can have good safety standards. The sizes for each part are shown in Figure 5, in millimeters.
(a) shaft
(b) Helmet, bracket
(c) Locking pin
Figure 5. Parts
The bearings are located at the junction of the helmet bracket, shaft, and locking pins. The bearings are two pieces between the shaft and the helmet bracket. Bearings use bolts and nuts with bolt sizes M4 and M8 and a nut size of 6. Details of the bearing drawings can be seen in Figure 6.
Figure 6. Bearing (Nut and Bolt)
Under the basic drawings and designs, the Ashby diagram was used to select the base material for the BC3 boccia helmet stick. We selected the value based on the vertical curve to compare with the horizontal curve based on the specified value; in this case, this is on the red axis boundary. The material requirements were determined according to the classification of strength, density, and Young's modulus, as shown in Figure 7. Materials that met the standards were obtained by selecting metal-based materials; therefore, stainless steel was used in this design [17]. The specifications of the materials used can be seen in Table 1.
Table 1. Specifications of stainless steel material
|
Density |
8E-06 kg/mm3 |
|
Young's Modulus |
193000 MPa |
|
Poisson's Ratio |
0.3 |
|
Yield Strength |
250 MPa |
|
Ultimate Tensile Strength |
540 MPa |
|
Thermal Conductivity |
0.0162 W/(mm C) |
|
Thermal Expansion Coefficient |
1.04E-05/℃ |
|
Specific Heat |
477 J/(kg ℃) |
(a) Strength-density
(b) Young’s modulus-density
(c) Strength-cost
(d) Thermal expansion-conductivity
Figure 7. Material selection
3.3 Static simulation
Static analysis on the boccia helmet stick was carried out using the Autodesk Fusion 360 and Ansys 2021 R2 software applications. The loading was carried out evenly on the surface directly exposed to the ball load. In this analysis, the pedestal was fixed rigidly on the surface of the stick–helmet connection. The load is given based on the weight of the ball, with a safety value of 2, which is 5.56 N. It is known that the accuracy of a simulation depends on the quality of the mesh [18]. Meshing was carried out with the specifications shown in Table 2. The meshing results have a good standard with a skewness of 0.54023 [19]. As shown in Figure 8, the contours of the simulation design changes are similar to each software used. Contours evenly distributed on the safety factor indicate that they have the same strength value. Although the displacement with the red contour indicates the most likely damage, it can be seen that, in the simulation using Fusion 360 software, the design has a maximum displacement value and a minimum safety factor of 0.004 mm and 9.15, respectively. While using the Ansys 2021 R2 software, the maximum displacement and minimum safety factor values are 0.006 mm and 15, respectively. The complete simulation results can be seen in Table 3. This indicates that the materials and material and framework structures used in the design have good safety standards [20].
Table 2. Specification of meshing
|
Software |
Nodes |
Elements |
|
Fusion |
119225 |
73528 |
|
Ansys |
110700 |
63938 |
As for bearing reliability, numerical analysis results show that bolt bearings are estimated to have a good safety factor from the design results. This is because the tensile stress of the bolt bearings used has a value smaller than the allowable tensile stress of the bolt bearings, as calculated in Table 4. Thus, this tool can operate with reliable power and last longer [21-23].
After the design analysis produced the required data, the next step was to plan the purchase of the necessary manufacturing goods. This was to ensure that the design could be carried out within the existing price constraints. For its manufacture, materials are needed with a total price of Rp 351.500, as shown in Table 5. In this case, the design is still within the range of production costs. In addition, this design is cheaper than other BC3 boccia helmets because it has a high strength value.
(a) Displacement, Fusion 360
(b) Safety factor, Fusion 360
(c) Displacement, Ansys 2021 R2
(d) Safety factor, Ansys 2021 R2
Figure 8. Simulation results
Table 3. Design strength simulation results
|
Software |
Displacement (mm) |
Strain (mm/mm) |
Stress (MPa) |
Safety Factor |
||||
|
Min |
Max |
Min |
Max |
Min |
Max |
Min |
Max |
|
|
Fusion 360 |
0 |
0.004059 |
9.88E-14 |
2.41E-04 |
1.18E-08 |
27.32 |
9.15 |
15 |
|
Ansys 2021 R2 |
0 |
0.006 |
-7.92E-06 |
8.28E-06 |
-0.58376 |
0.61005 |
15 |
15 |
Table 4. Numerical analysis of bearings
|
M4x0.7. Bolt |
M8x1.25. Bolt |
||||||
|
Type |
Formula |
Results |
Information |
Type |
Formula |
Results |
Information |
|
d |
Bolt property |
4 |
Nominal diameter of the thread (mm) |
d |
Bolt property |
8 |
Nominal diameter of the thread (mm) |
|
de |
Bolt property |
3.515 |
Effective diameter(mm) |
de |
Bolt property |
7.188 |
Effective diameter(mm) |
|
in |
Bolt property |
3,242 |
Thread core diameter(mm) |
in |
Bolt property |
6,647 |
Thread core diameter(mm) |
|
W |
Ball properties |
0.556 |
Load (kg) |
W |
Ball properties |
0.556 |
Load (kg) |
|
τa |
Bolt property |
6 |
Allowable Tensile Stress (kg/mm2) |
ta |
Bolt property |
6 |
Allowable Tensile Stress (kg/mm2) |
|
v |
property |
2 |
Safety factor |
v |
property |
2 |
Safety factor |
|
τa |
τa.v |
3 |
Final allowable tensile stress (kg/mm2) |
ta' |
a.v |
3 |
Final allowable tensile stress (kg/mm2) |
|
τt |
$\frac{4 . W}{\pi \cdot d i}$ |
0.067387464 |
Tensile Stress (kg/mm2) |
yyyy |
$\frac{4 . W}{\pi \cdot d i}$ |
0.016031 |
Tensile Stress (kg/mm2) |
Table 5. Bill of materials
|
No |
Name |
Specification |
Quantity |
Unit price (Rp. ,-) |
Total price (Rp. ,-) |
|
1 |
Stainless Steel |
Diameter 32 mm, length 50 cm |
1 |
45000 |
45000 |
|
2 |
Stainless Steel |
Diameter 20 mm, length 20 cm |
1 |
35000 |
35000 |
|
3 |
CNC Hose |
30 cm long, made of plastic |
1 |
65000 |
65000 |
|
4 |
myrrh |
M6 |
1 |
1000000 |
1000000 |
|
5 |
Bolt |
M4 |
1 |
2000 |
2000 |
|
6 |
Bolt |
M8 |
1 |
2000 |
2000 |
|
7 |
Ring |
|
6 |
250 |
1500 |
|
9 |
Lathe Cost |
|
1 |
200000 |
200000 |
|
Total |
351500 |
||||
3.4 Manufacture
In making a boccia helmet, the design is divided into two steps: determining the use of the machine and determining the quality of each part [24]. It can be seen that the manufacturing plan is divided into six parts, of which three parts are produced independently, and three parts are purchased, as shown in Table 6. It has an effective and efficient value for the planned parts. Manufacturing classifications are shown in Table 7.
Manufacturing was successfully carried out, as shown in the figure. Splicing for each part was performed to find out manufacturing errors in each part. Inspections were carried out by visualization and testing by athletes, as shown in Figure 9. The boccia helmet has a good safety and comfort value and can be used as a supporting tool for BC3 boccia sports competitions [2].
3.5 House of Quality
The quality of the tool design was assessed using the house of quality system. The evaluation that was conducted found that the designed product can meet the consumer needs better than other products. The design results show that it is most valuable due to a sturdy frame, the fact that it can be used by many people, and because it does not consume a lot of power during operation. Compared to the competition or other products [7], the design has a better score (39%), as shown in Figure 10.
|
(a) Results |
(b) BC3 boccia helmet trial |
Figure 9. BC3 boccia helmet
Figure 10. House of quality products
Table 6. Machining process classification
|
Part Number |
Part Name |
Tapping |
Counterboring |
Drilling |
Milling |
Grinding |
Shaping |
Fillet |
chamfer |
Other |
|
1 |
Base/main stand |
M8 |
N |
N |
Y |
N |
N |
N |
N |
|
|
2 |
Axis |
M12 |
N |
N |
Y |
N |
N |
N |
N |
|
|
3 |
Lock pin |
M4 |
N |
N |
Y |
N |
N |
N |
N |
|
|
4 |
M8. bolt |
|
|
|
|
|
|
|
|
Purchased |
|
5 |
M4. bolt |
|
|
|
|
|
|
|
|
Purchased |
|
6 |
M6 nut |
|
|
|
|
|
|
|
|
Purchased |
Table 7. Manufacturing Classification
|
Part |
DFA Complexity |
Functional Analysis |
Error Proofing |
Handling |
Insertion |
Joint |
||||||||||||
|
Part Number |
Assembly Image |
Number of Parts (Np) |
Number of Interfaces (NI) |
Part Can Be Standardized |
Cost (Low/Medium/High) |
Assemble Part Wrong Way around |
Tangle/Nest/Stick Together |
Flexible/Fragile/Sharp/Slippery |
Pliers/Tweezers/Magnifying Glass |
Difficult to Align/Locate |
Holding down Required |
Resistance to Insertion |
Obstructed Access/visibility |
Re-oriented Work Piece |
Screw/Drill/Twist/Rivet/Bend/Crimp |
Weld/Soldering/Glue |
Paint/Lube/Heat/Apply Liquid or Gas |
Test/Measure/Adjust |
|
1 |
Base/main stand |
1 |
1 |
N |
M |
Y |
N |
N |
N |
Y |
Y |
N |
N |
Y |
Y |
N |
N |
Y |
|
2 |
Axis |
1 |
1 |
N |
H |
Y |
Y |
N |
N |
Y |
Y |
N |
N |
Y |
Y |
N |
N |
Y |
|
3 |
Lock pin |
1 |
1 |
N |
M |
Y |
N |
N |
N |
Y |
Y |
N |
N |
Y |
Y |
N |
N |
Y |
|
4 |
M8. bolt |
1 |
1 |
Y |
L |
N |
N |
N |
N |
N |
N |
N |
N |
N |
Y |
N |
N |
N |
|
5 |
M4. bolt |
1 |
1 |
Y |
L |
N |
N |
N |
N |
N |
N |
N |
N |
N |
Y |
N |
N |
Y |
|
6 |
M6 nut |
1 |
1 |
Y |
L |
N |
N |
N |
N |
N |
N |
N |
N |
N |
Y |
N |
N |
N |
The design of the BC3 boccia helmet was successfully carried out. The BC3 boccia helmet is intended for BC3 boccia athletes at NPC Surakarta. The BC3 boccia helmet stick became the focus of the design process. A stick with a volume of 105350 mm3 and a weight of 0.82 kg was designed. The design was divided into three main parts: the helmet bracket, shaft, and lock. The bearings used M4 and M8 bolts. The design process was equipped with a simulation of design strength. With meshing with a skewness quality of 0.54023, the maximum displacement value is 0.006 mm, and the minimum safety factor is 9.15. The manufacturing results produced a stick helmet with adequate accuracy and safety standards. A house of quality design of 39% indicates that it meets consumer needs better than other products.
This research was fully supported by the PNBP grant from the Universitas Sebelas Maret, Indonesia, with the contract number 260/UN27.22/HK.07.00/2021 of the Hibah Riset Grup Pengabdian scheme.
[1] Pankowiak, A. (2020). National Paralympic sport policy interventions and contexts influencing a country’s Paralympic success: A realist-informed conceptual framework. Doctoral dissertation, Victoria University.
[2] Koukourikos, A.A., Lee, M., Bernards, N. (2017). USA Boccia Ball Ramp for Athletes with Quadriplegia.
[3] Haris, M.A., Doewes, M., Liskustyawati, H. (2020). Development of boccia cerebral palsy's national athlete achievement in the Indonesian national paralympic committee. Budapest International Research and Critics in Linguistics and Education (BirLE) Journal, 3(2): 784-794. https://doi.org/10.33258/birle.v3i2.940
[4] Kasih, A.M., Hidayatullah, M. F., Doewes, M. (2021). Evaluation of boccia sports achievement coaching program using cipp model at the boccia NPC Indonesia national training center. International Journal of Humanities and Education Development (IJHED), 3(3): 144-147. https://doi.org/10.22161/jhed.3.3.15
[5] Al Haris, M., Doewes, M., Likustyawati, H. (2020). Sistem organisasi pembinaan atlet nasional boccia cerebral palsy di National Paralympic Committee Indonesia. In Prosiding Seminar Nasional Fakultas Ilmu Kesehatan dan Sains, 1(1). https://doi.org/10.15797/concom.2019.23.009
[6] Kasih, A.M., Hidayatullah, M.F., Doewes, M. (2020). Ketercapaian pelaksanaan program pembinaan prestasi olahraga boccia dengan menggunakan model CIPP di pelatnas boccia NPC Indonesia. In Seminar Nasional Keindonesiaan (FPIPSKR), 2(1): 247-252.
[7] Arifin, Z., Prasetyo, S.D., Prabowo, A.R., Cho, J.H. (2021). Preliminary design for assembling and manufacturing sports equipment: A study case on Aerobic Walker. Int J Mech Eng Robot Res, 10(3), 107-115. https://doi.org/10.18178/ijmerr.10.3.107-115
[8] Oddershede, A.M., Quezada, L.E., Valenzuela, J.E., Palominos, P.I., Lopez-Ospina, H. (2019). Formulation of a manufacturing strategy using the house of quality. Procedia Manufacturing, 39: 843-850. https://doi.org/10.1016/j.promfg.2020.01.417
[9] Yin, C., Hou, S. (2019). Application design for manufacture and assembly to improving product design and development performance. In 2019 ASABE Annual International Meeting. American Society of Agricultural and Biological Engineers, pp. 1-9. https://doi.org/10.13031/aim.201900289
[10] Jaggi, N., Chand, K., Mukhija, P., Guha, P., Chathuranga, K., Lalitharathne, S., Kulasekera, A.L., Gopura, R. (2018). Design and simulation of autonomous fire fighting robots for forests. In 2018 4th International Conference on Computing Communication and Automation (ICCCA), pp. 1-5. https://doi.org/10.1109/CCAA.2018.8777618
[11] Marxen, L., Bertero, V.V., Paltrinieri, N., et al. (2001). Concurrent engineering and DFMA/DFX in the development of automotive components. Procedia CIRP 2001, 41: 241-260. https://doi.org/10.1016/j.ssci.2019.06.001
[12] Budiman, F.A., Septiyanto, A., Sudiyono, S., Musyono, A.D.N.I., Setiadi, R. (2021). Analisis tegangan von mises dan safety factor pada chassis kendaraan listrik tipe in-wheel. Jurnal Rekayasa Mesin, 16(1): 100-108. https://doi.org/10.32497/jrm.v16i1.1997
[13] Gokcek, M. (2012). Mechanical Engineering. IntechOpen. https://doi.org/10.5772/2397
[14] Chow, H.W., Wu, D.R. (2019). Outdoor fitness equipment usage behaviors in natural settings. International Journal of Environmental Resarch and Public Health, 16(3): 391. https://doi.org/10.3390/ijerph16030391
[15] Olewnik, A., Lewis, K. (2008). Limitations of the House of Quality to provide quantitative design information. International Journal of Quality & Reliability Management, 25(2): 125-146. https://doi.org/10.1108/02656710810846916
[16] Morrell, N.E. (1987). Quality function deployment. SAE Tech Pap, 101-21. https://doi.org/10.4271/870272
[17] Street, T. (2018). Ashby Chart inspired design. 1-30.
[18] Harsito, C., Xaverius, A., Prasetyo, S.D., Wulansari, P., Pradana, J.A. (2021). Conveyor Pengangkut Sampah Otomatis dengan Load Cell dan Flow Sensor. Journal of Mechanical Engineering Manufactures Materials and Energy, 5(1): 18-33. https://doi.org/10.31289/jmemme.v5i1.4177
[19] Supriyanto, A., Furqoni, L., Nurosyid, F., Hidayat, J., Suryana, R. (2016). Effect of sintering temperatures and screen printing types on TiO2 layers in DSSC applications. AIP Conference Proceedings, 1717: 040001. https://doi.org/10.1063/1.4943444
[20] Arifin, Z., Prasetyo, S.D., Triyono, T., Harsito, C., Yuniastuti, E. (2020). Rancang bangun mesin pencacah limbah kotoran sapi. Jurnal Rekayasa Mesin, 11(2): 187-197. https://doi.org/10.21776/ub.jrm.2020.011.02.6
[21] Caesarendra, W., Tjahjowidodo, T. (2017). A review of feature extraction methods in vibration-based condition monitoring and its application for degradation trend estimation of low-speed slew bearing. Machines, 5(4): 21. https://doi.org/10.3390/machines5040021
[22] Prasetyo, S.D., Harsito, C., Sutanto, Suyitno. (2019). Energy consumption of spray dryer machine for producing red natural powder dye and its stability. In AIP Conference Proceedings, 2097(1): 030076. https://doi.org/10.1063/1.5098251
[23] Arifin, Z., Tjahjana, D.D.D.P., Rachmanto, R.A., Suyitno, S., Prasetyo, S.D., Trismawati, T. (2020). Redesign mata bor tanah untuk pembuatan lubang biopori di desa puron, Kecamatan Bulu, Kabupaten Sukoharjo. Mekanika: Majalah Ilmiah Mekanika, 19(2): 60-67. https://doi.org/10.20961/mekanika.v19i2.43393
[24] Arifin, Z., Prasetyo, S.D., Suyitno, S., Tjahjana, D.D.D.P., Rachmanto, R.A., Juwana, W.E., et al. (2020). Rancang bangun alat elliptical trainer outdoor. Mek Maj Ilm Mek, 19: 104. https://doi.org/10.20961/mekanika.v19i2.44325
