Search

With the growing rate of the COVID-19 case that has not decreased significantly, healthcare workers are required to work extra both in the hospital and for the corpses' funeral process. Since the corpse condition is different from a normal corpse, the treatment must also be different. The objective of this paper is to propose a portable device as an education tool that can ease the burial process of COVID-19 corpse. This device can be operated by only two people, and the load is bearable because there is a worm gear system that helps the pulley system. Other supporting features will be explained in this paper. Theoretical strength analyses are conducted under static and fatigue loading. From the static case, based on the Maximum Shear Stress failure criterion, the safety factors on the critical parts are 1.28 and 5.67. Then, fatigue strength analysis is conducted to provide life prediction for this device. As a result, the fatigue safety factors are found to be greater than 1. These findings indicate that the proposed design is appropriate for real-world use and can be further studied for manufacturing.

Most of child safety seats for motorcycle available in Indonesian market do not provide enough safety for the children passenger, especially for special needs child. This makes a special needs child cannot ride a motorcycle and prefer to use an automobile for their transportation means. However, it becomes a problem for a low-income family that can only afford a motorcycle. To address this problem, the present work aims to i) design a portable child safety seat for those with special needs that can be placed at the back side of the motorcycle, ii) provide safety feeling to the child by making a capsule-like shape for overall protection, iii) demonstrate an education case-study for mechanical design course. Discussion on how to determine the specification based on problem definition as well as the explanation on the design process of seat’s frame and body are provided. This work can be also used a reference for problem-based learning in mechanical engineering design course.

The existence of top burrs in micro-scale features produced by milling process can deteriorate the surface quality of a product. Ductile metals, such as aluminum alloys, are prone to suffer from top burrs formation after a slot-milling process. A brief review on the state-of-the-art of burr removal process in micro-scale milling is provided in this paper. Various deburring methods were reportedly able to remove the burrs in micro-scale features, however a much simpler method is still needed. In the present work, a deburring process by stainless steel end brushing is introduced for aluminum mould used in microfluidic device fabrication. The micro-scale features are produced by slot-milling process followed by the deburring process. The deburred moulds are then visually observed using optical microscope and Scanning Electron Microscope (SEM) and the average surface roughness and its features profile are measured using 3D Laser Scanning Confocal Microscope. As a result, the proposed deburring method can successfully remove the top burrs, as indicated by a height reduction of about 21% due to the removal action by the brush. Hence, a burr-free embossing mould with complex shape channel features can be produced by milling and by applying a simple deburring process using stainless steel end brush.

A child safety seat is usually installed on a motorcycle when the rider needs to travel along with a small child. However, limited products can be found in Indonesia where motorcycle is the most popular transportation mode. The main objective of this paper is to propose a safe and comfortable child seat design, then perform theoretical strength analyses to evaluate its safety factor. The proposed child safety seat is designed for children under five years old with average weight of 24.2 kg and height of 70–100 cm and is targeted for Honda Vario Techno 150 scooter. The seat is installed on the rear part of the motorcycle, and equipped with a hinge mechanism, hence the rider can refill the gasoline tank by flipping the seat up. Theoretical calculation of safety factors under static and dynamic (fatigue) loading conditions was conducted by two failure criteria, i.e. the Modified Goodman and Gerber. As a result, the fatigue safety factors for Modified Goodman and Gerber criteria are 1.05 and 1.02, respectively. These results imply that the proposed design is reliable and can be considered for real application. In addition, this paper demonstrates a comprehensive machine design procedure which can be referred as a lecture note in mechanical engineering.

This paper introduces a primary design of a child safety seat for motorcycle Honda Vario 150 eSP along with its static and fatigue strength analyses. The design is equipped with an innovation in which a recliner mechanism is built in the seat so that the backrest can be adjusted either in an upright or tilted position. The mechanical strength analyses aim to ensure the child seat is safe for the rider and child. The analyses are carried out on the critical components of the child seat, which are the backrest, body-seat, and clamping support by theoretical approach to find the safety factor. As a result, the proposed child seat design can offer a safety factor of 78 for the body-seat component under static, and 466 for the clamping support under fatigue. This means the proposed design can provide a good safety. Moreover, the high safety factor can allow more improvements and modification for further optimization of the structure and materials. In addition, this work can be referred as a lecture note for machine element course.

Indonesia faces decreasing in its number during period of 2018-2019 according to SINTA (Indonesian scientific indexing) database. This situation is alarming amid country’s effort to improve its research and development from which the scientific publication has been used as a measure. This article presents a dataset of bibliometric from all Indonesian institutions (424 institutions as of January 2020) indexed by Scopus database. We collected data on documents per year and document type. Different from other datasets, this article presents longitudinal data from 2014-2019, in which during this period dramatic change occurs from steep rise, exponential, and degradation during 2018-2019. We analyzed publication number from leading institutions at different points in time and compared document types (i.e., number of journal article and conference paper, in which both types are the driving force of Indonesia’s growing scientific publication number). Since this dataset covers all country’s institutions, it is potential for reuse by policy makers in research and development, researchers from each institution, as well as other stakeholders.

In turbomachinery, such as turbine, pump, and valve, components damage caused by collapsing cavitation bubbles has been a critical issue that needs a proper solution. For this reason, investigation on the cavitation erosion behavior of materials as well as the life prediction techniques has been extensively conducted. Moreover, a number of repairing techniques, such as by a surface coating of polymeric materials, has been established. However, in real operation, cavitation is actually not the only load acquired by the components. Other external loads, such as centrifugal force and hydraulic pressure, may also affect the generation of damage. Therefore, its effect on the lifetime needs to be considered carefully. In this paper, the behavior of cavitation damage of epoxy resin specimens subjected to uniaxial tensile loading is reported. A self-developed testing device was used to conduct a cavitation test based on ASTM G32 while at the same time exerting a constant uniaxial tensile load to the specimen. Using this device, various levels of tensile stress effect on the cavitation damage was examined. As a result, besides erosion damage, we revealed that the specimens demonstrated fracture when a certain tensile load was applied. Furthermore, as the tensile load was increased, the time to fracture was shortened significantly, indicating the pronounced effect of tensile stress on the damage formation. The crack growth mechanism was then analyzed by fractography. The result indicated that the crack propagation under a mixed condition of cavitation and tensile loads was most likely driven by the combination of creep deformation and fatigue-like crack growth. Finally, a mathematical relationship between tensile stress and cavitation damage life was proposed. The relationship is important to enhancing the existing theory of cavitation damage evaluation in e.g. turbomachinery application.

Almost every year, floods disaster becomes the scourge of many countries in the world, including Indonesia. When the flood comes and submerges the houses, every item and household furniture in it will also be submerged in flood water. Furniture that is heavy and difficult to move, especially electronic equipment such as refrigerators, may be left by the owner when a flood occurs. To prevent the furniture from submerging, a lifting kit is needed. For this reason, the purpose of this work is to design a mechanical tool/kit that can lift or elevate the electronic furniture such as refrigerator to a higher position and avoid the damage caused by flood. The kit is expected to be able to cover a 100 x 80 cm base of the refrigerator with maximum load of 200 kg. The elevation of the lifting kit is set to be higher than 50 cm. Calculation for the stress and fatigue analysis is also performed to determine the strength of the structure. As a result, the obtained safety factors for the critical components under static and fatigue loading conditions show values of more than one, indicating the product is safe for real operation. In addition, the required torque to produce the elevation is also calculated and discussed.

Following on the 2008-2012 OECD Assessment of Higher Education Learning Outcomes (AHELO) feasibility study of civil engineering, in Japan a mechanical engineering learning outcomes assessment working group was established within the National Institute of Education Research (NIER), which became the Tuning National Center for Japan. The purpose of the project is to develop among engineering faculty members, common understandings of engineering learning outcomes, through the collaborative process of test item development, scoring, and sharing of results. By substantiating abstract level learning outcomes into concrete level learning outcomes that are attainable and assessable, and through measuring and comparing the students’ achievement of learning outcomes, it is anticipated that faculty members will be able to draw practical implications for educational improvement at the program and course levels. The development of a mechanical engineering test item bank began with test item development workshops, which led to a series of trial tests, and then to a large scale test implementation in 2016 of 348 first semester master’s students in 9 institutions in Japan, using both multiple choice questions designed to measure the mastery of basic and engineering sciences, and a constructive response task designed to measure “how well students can think like an engineer.” The same set of test items were translated from Japanese into to English and Indonesian, and used to measure achievement of learning outcomes at Indonesia’s Institut Teknologi Bandung (ITB) on 37 rising fourth year undergraduate students. This paper highlights how learning outcomes assessment can effectively facilitate learning outcomes-based education, by documenting the experience of Japanese and Indonesian mechanical engineering faculty members engaged in the NIER Test Item Bank project.First published online: 30 November 2017

Continuous increment of plastic bottle waste creates new problems of space-consuming both in landfills and the ocean. Hence, plastic bottle waste recycling process and volume reduction are needed. This paper proposes a component design concept of a pressing machine to press plastic bottle wastes for volume reduction purpose. The proposed design essentially brings a concept of combining hydraulic and gear power to produce the pressing mechanism. Some boundary conditions were applied, such as force magnification, weight, and dimension; thus, the machine can be portable because of small scale dimension and light weight. Furthermore, the machine can be used as a demonstration machine for education purpose.

A helmet is used to protect the head of motorcycle rider especially when an accident happens by absorbing the impact/crash load. In Indonesia, wearing a helmet when riding a motorcycle is obligated by the constitution. Hence, in line with the quick growth of online motorbike and taxi service, carrying a personal helmet has become a common need. Yet, it becomes troublesome to carry and store the helmet due to its big size. This paper introduces a primary design idea of a foldable helmet for motorcycle rider by fulfilling the safety standard of SNI (Indonesian National Standard). The proposed helmet uses hinge components that allow the folding mechanism. Strength analysis of the hinge-pin lock system is discussed in this paper. From the result, it was confirmed that the foldable helmet could withstand a loading requirement of 3000 N at the joint system (hinge) as required by SNI. The proposed folding mechanism can reduce a helmet volume up to 50% smaller than the non-foldable one. Furthermore, this study is expected to give contribution to the engineering product design.

Safety is an important thing while riding a bicycle or motorcycle. Using a helmet is one of the solutions to increase safety of the rider, but sometimes people are too lazy to bring the helmet because of its big size. In the present work, a foldable helmet adopting the Armadillo concept was proposed to make people feel more comfortable in carrying the helmet. The design also follows the safety standard required by the SNI (Indonesia National Standard). A locking system for the folding mechanism is discussed, and a honeycomb foam for impact absorber is considered in the design. As a result, the proposed foldable helmet can have a reduction volume of 23.75% compared with the non-foldable one. This work is expected to contribute to the innovative engineering design field.

This work studies the method of sorting plastic bottles-waste. Currently, the recycling treatment for a different type of plastic bottle wastes is similar although they are made of different plastic material. The disadvantage of the current method is that the produced plastic is an unknown type of plastics. To perform recycling treatment of similar types of plastic bottle waste, the plastic-bottle waste needs to be sorted based on their material characteristics. We propose a sorting method of the plastic-bottle waste by using a barcode scanner. A database on plastic-bottle waste based on their barcode number, which then categorized their material characteristics, is first created. In this paper, the diagram of the sorting process is given.

Commonly, crispy characteristic is the desirable texture of dry food, especially in crisp products. The term crispness itself is qualitatively determined by the perception of human sensory. Thus, a quantitative expression is needed. The present work introduces a study to analyze the correlation between the crispness and compressive mechanical behavior of potato crisps as a preliminary step to quantify crispness level of crisp products. Potato crisp samples were exposed to room air in several specific durations. The crisp samples were assessed one by one by running a uniaxial compression test using two parallel plates. The load and displacement curve relationship were measured simultaneously during crisp deformation at a constant speed. The result indicated that there is a relationship between the crispness of the crisps and the strain energy up to 10% strain. Yet, the result has not perfectly mimicked the apparent crispness of the samples. This analysis is expected to contribute to the food engineering field in terms of crispness quantification of a dry food.

This paper discusses the methodology of design and analysis of a child seat for motorcycles. After realizing the dangers of an unrestrained child in motorcycles, this seat offers a solution to the problem. The seat features sliding beams that allow the user to access the under-seat compartment of the motorcycle and the fuel tank, without requiring any disassembly of the child seat. The dimensions are measured and considered when designing in a graphical application. Once the assembly drawing is completed, the seat is analyzed to identify critical parts of the seat to ensure failure does not occur. It is concluded that our design can withstand static loading but is predicted to fail due to fatigue after 81× 103 cycles under the assumption of accelerating from 0 to 50 km/h in 5 seconds. However, since that is not deemed to be fully optimized due to having a finite life, the material and dimensions are changed so that an infinite life can be predicted.

Miura-origami pattern has taken interest of many engineers and mathematicians due to its unique foldability and wide range of engineering applications. However, its mechanical behavior is yet to be fully explored, especially when it is made by additive manufacturing (3D printing) method. In this paper, the compressive behavior of 3D printed column structure using the Miura-origami pattern is investigated. Polylactic Acid (PLA) material was used to make the specimen with various printing parameters, i.e. infill pattern and density. Moreover, six kind of origami patterns with different folding angle and wall thicknesses were tested. Finally, the elastic and plastic deformation behavior under compressive load is examined. The result is useful to develop a finite element model which can be utilized to comprehensively explore the mechanical behavior under complicated loading condition. In addition, this study is expected to give impact on developing an innovative engineering design by the use of Miura-Ori pattern, for example is on designing an energy absorption device such as prosthetic leg and automotive crash box.

This paper presents the finite element analysis (FEA) of 3D printed Miura origami column under uniaxial compressive loading condition. The finite element model (FEM) was developed under elastic-perfectly plastic material model. Investigation on the yield strength and compressive modulus with two varied parameters, i.e. angle and thickness of the Miura origami column was conducted. Abaqus 6.14 software was used to conduct the simulation of compression test. The simulation result is then compared with and examined to the referred experimental data. From the simulation, it was revealed that the results from FEA of Miura-ori column with θ = 90° and t = 2 mm showed good agreement with the referred experimental data. However, FEA results mostly overestimates the mechanical properties. This discrepancy could be due to the existence of imperfections and anisotropic material of 3D printed structures.

This paper aims to demonstrate a measurement method of pressure wave speed in stainless-steel pipe filled with water caused by water hammer phenomenon. The pressure wave is generated using a self-developed drop impact testing equipment. An impactor is dropped to collide a buffer which then induces the water hammer phenomenon. The generated pressure and its propagation speed in the water are carefully measured here. Pressure measurement is conducted by a pressure transducer, while pressure wave speed is measured by two methods, which utilize peak time of the pressure recorded by pressure transducer and peak time of strains recorded by two strain gages positioned in a different location. These strain gages are oriented to the circumferential direction of the pipe. Measurement result shows that at 1.5 m height, impact pressure of between 0.86 to 1.16 MPa and wave velocity of 1250 m/s were obtained. From the experimental results, the characteristic of pressure wave in the water was able to be observed.

The elastic behavior of aluminum alloy foam under uniaxial loading and bending conditions is studied by experimental investigations and theoretical analyses. It is found from the experiments that the elastic moduli measured from three- and four-point bending tests as well as flexural vibration tests are significantly larger than the corresponding elastic moduli measured from uniaxial compression tests. This discrepancy cannot be described by the well-known elastic modulus equation introduced by Gibson and Ashby for foam materials. Theoretical analyses are carried out to explain the discrepancy and to improve the elastic modulus equation of Gibson and Ashby. In the analyses, unit-cell models are proposed, and elastic modulus equations for both uniaxial loading and bending conditions are derived. The derived equations offer a good description of the discrepancy as well as reveal the prominent role of cell local deformation under bending condition. Furthermore, the present work offers clear evidence that the classical continuum theories, such as Bernoulli–Euler beam theory, are inadequate for describing the elastic bending behavior of metal foams.

We investigated the effect of charge to the interaction between a hydrogen molecule and a hydrogenated vacancy V11 in graphene surface based on density functional theory calculation. V11 is graphene mono-vacancy with two hydrogen atoms adsorbed at the edge of vacancy. The hydrogen molecule physisorbed on deformed V11 is shown to dissociate producing a known stable vacancy V211, in which two carbon atoms are mono-hydrogenated and another is di-hydrogenated at the edge of the vacancy. We found that additional electron charge to the system could influence the reaction pathways and reduced the energy barrier for dissociation adsorption and desorption process provides a basic understanding in the mechanism of hydrogenation processes on graphene vacancy for hydrogen storage aplication.

This paper presented the investigation of failure mechanism of plastic shredding machine’s flange coupling which is made of cast steel. The machine unexpectedly stalled a few minutes after High-Density Polyethylene (HDPE) plastic bottles were fed into the machine. It was discovered afterward that the flange broke with the large crack surface. Finite element analysis (FEA) was performed to find the position and value of the critical stresses in the flange during operating condition. Subsequently, hardness test was conducted on the flange body to determine the Brinell hardness which was then converted into the approximate ultimate tensile strength (σu). As a result, a maximum Von Mises stress of 287 MPa was confirmed from the FEA to be concentrated in the flange’s keyway. Although this was found to be lower than the approximate σu obtained from hardness testing i.e. 449 MPa, the critical stress indicated an unstable condition which may induce a crack initiation any time when vibration or dynamic load occurs. Based on these analyses, it was concluded that the failure had been initiated by dynamic rather than static loading generated during machine stall condition. The dynamic load caused crack initiation at a stress concentration point of the keyway. The crack then propagated rapidly, breaking the flange body.

Aluminum alloy foam has been an attractive material to be used in many engineering applications due to its novel properties and behaviors in combination with the light-weight structure. Many researches had been conducted to enable and explore more widespread engineering applications of this material; however, its mechanical responses are yet to be fully understood. The work presented in this paper is aimed at studying the elastic bending behavior of aluminum alloy foam by experimental investigations and theoretical analysis. From the experiments, the measured flexural moduli are found to be significantly larger than the corresponding Young's moduli. Moreover, the foam's stiffness equation introduced by Ashby et al. for the design-guide is found to be not suitable for estimation of the flexural moduli. The theoretical analysis was carried out to identify the mechanism responsible for generating the discrepancy. We found that the different in cell local-deformation under uniaxial loading and bending condition plays a prominent role in the discrepancy, where in particular, the effect of cell-face stretching was found to be dominant in bending condition.