Generally, there are two types of working style, i.e., some people work in sitting conditions, and the remaining work mostly in a standing position. For people working in a standing position, they can spend hours in a day doing their work standing. These people do not realize that it can cause medical issues, especially for the feet, namely biometric problems. In addition, several doctors in Indonesia are already aware of this issue and state that the biometric problems faced by those kinds of people can be predicted from the load distribution on the foot. However, the tool used by the doctors in Indonesia to measure biometric problems is not a digital tool. Therefore it is very difficult to measure and predict the biometric problems quantitatively. This study aims to develop a low-cost static load measuring device using force-sensing resistor (FSR) sensors. The measuring instrument is designed in the form of a pressure plate platform which consist of 30 FSR 402 sensors. The sensors are placed right underneath the display area of the foot, 15 sensors on the soles of the left and right feet. Ten students from the Department of Mechanical Engineering, Diponegoro University (five men and five women) were asked to stand on the platform. Each subject also measured foot length (FL) to estimate shoe size, foot area contact (FAC) for validation between genders, and foot type using the digital footprint tools. From the results of measurements obtained for the left foot in the medial mid foot area, i.e., in sensors 5 and 7, not exposed to the load, on almost all subjects except subject number 3 with a load of 0.196 kg on sensor 7. The highest average load occurs in the heel area i.e., sensor 1 measured 0.713 kg and the smallest average load occurs in the five sensors, with 0 kg. A static load gauge that is designed to be used to measure each leg area for subjects with a shoe size of 40–42 with low price to be held in hospital-orthopedic hospitals and biomechanical research centers.
The recovery of a fractured femur using the plate and screw internal fixation. The plate internal fixation is made of metal has good mechanical strength, but causes allergic reactions, secondary surgery, stress shielding and high costs. Evaluation of the lack of metal, now developed biodegradable polymers use Polylactide (PLA) and Poly ɛ-caprolactone (PCL). The advantages of PLA and PCL materi-als can control the rate of degradation and increase mechanical strength. Manufac-turing processes of the plate fixation internal using cold isotactic pressing. Inde-pendent variable on the PLA/PCL blends from 90/10, 80/20, 70/30, and 60/40 wt% and tested for FTIR, XRD, SEM, density and porosity. Result from adding PCL make the degree of crystallinity is decreased significantly. The formation of semi-crystalline the with peak width smaller and the crystal size bigger in the 60PLA sample. PLA/PCL blends largely formed bonding and some immiscibility in the form of small flakes and cavities after the addition of PCL content. Large cavities reduce density and increase porosity which can affect mechanical proper-ties. 90PLA sample has high density and low porosity of 1,186 g/cm3 and 4% porosity, respectively.
In this paper, the industrial application of detailed heat integration in the chlorobenzene production plant has been solved by using the Pinch design method. Designing a Heat Exchanger Network (HEN) through pinch analysis is an effective energy integration technology. In addition, minimizing unit and cost, operability and process control are essential parameters for selecting a suitable HEN design. In this research, the HEN of the existing process has been designed and analyzed using HINT software to minimize energy consumption and cost, thereby achieving maximum energy recovery. The analysis shows that the existing plant has been well integrated, and sound energy-saving effects and minimum energy requirements have been observed through the energy integration between processes. The total energy saving has been 91.80 %, while the energy recovery for heating and cooling have been 86.99 % and 96.23 %, respectively. Based on the economic analysis, the total annual cost of the proposed HEN design has been calculated to be 80912.5 $.
<div class="WordSection1"><div class="WordSection1"><p>Aluminium komposit secara luas digunakan untuk aplikasi kinerja tinggi seperti di otomotif, militer dan kedirgantaraan. <em>Stir casting</em> merupakan salah satu metode yang digunakan untuk memproduksi AMC (<em>Aluminium Matrix Composite</em>). Parameter dalam metode <em>stir casting</em> yang harus dipertimbangkan ketika proses manufaktur diantaranya adalah temperatur pengadukan, kecepatan pengadukan dan perlakuan pada partikel penguat karena akan berpengaruh terhadap sifat fisik dan mekanik komposit. Penelitian ini dilakukan untuk mengetahui pengaruh pemanasan awal serbuk Al<sub>2</sub>O<sub>3 </sub>terhadap porositas, kekerasan, laju keausan spesifik dan koefisien gesekan komposit Al6061-Al<sub>2</sub>O<sub>3</sub>. Proses manufaktur komposit dilakukan pada temperatur pengadukan 720-740°C, kecepatan pengadukan 600 rpm dan variasi perlakuan <em>preheat </em>pada partikel penguat Al<sub>2</sub>O<sub>3</sub> dengan suhu ruang, 150℃ dan 300℃. Hasil penelitian menunjukkan bahwa perlakuan <em>preheat</em> pada partikel penguat Al<sub>2</sub>O<sub>3</sub> berpengaruh terhadap porositas, kekerasan, laju keausan spesifik dan koefisien gesek komposit. Perlakuan <em>preheat </em>pada partikel penguat Al<sub>2</sub>O<sub>3</sub><em> </em>mampu menurunkan porositas, meningkatkan kekerasan dan koefisien gesek, serta menurunkan laju keausan spesifik komposit. Pemberian perlakuan <em>preheat</em> yang optimal didapat pada suhu 300℃.</p></div></div>
This study aims to investigate the mechanical properties of bamboo apus (gigantochloa apus) as a natural reinforced composite material. Bamboo’s laminates of gigantochloa apus were used as reinforcement on the epoxy resin matrix. The parameters examined in this study are the configuration of lamina and compaction pressure. Laminate configuration varies in the number, thickness and direction of the lamina. Compaction pressures of 1.5 MPa, 2 MPa, and 2.5 MPa were used to fabricate the Laminated Bamboo Composites (LBCs). The stem of bamboo with a length of 400 mm was split to obtain bamboo lamina with a size of 400×20 mm. The thickness of bamboo lamina is varied between 1 mm, 1.5 mm, and 2 mm. The bamboo lamina is then preserved by watering it with a preservative solution in the form of 2.5 % sodium tetraborate solution and dried in an oven until the water content reaches 10 %. LBCs were made with a hand lay-up method. After the LBCs were molded, they were pressed with 3 variations of dies compaction 1.5 MPa, 2 MPa and 2.5 MPa. The tensile and bending tests were carried out on the LBCs. Tensile testing is performed in accordance with ASTM standard D3039 and the bending tests were conducted based on ASTM standard D7264. The results show that at each compaction pressure, the highest tensile and bending strength was achieved by LBCs with a thickness of 1 mm of bamboo lamina and 7 layers of bamboo laminates. The LBC with thinner bamboo lamina reinforcement and more layers has the highest tensile strength and bending strength, even it has a lower mass fraction. The LBCs with laminates oriented 0° exhibited greater tensile and bending strengths than the LBCs with laminates structured –45°/+45° and 0°/90°. The LBCs with the 0° laminates direction is matrix fracture followed by lamina fracture. In the 0°/90° direction, matrix fracture is followed by delamination in the 90° and 0° laminates direction. Delamination and lamina clefting were observed in LBCs with laminates oriented +45°/–45°.
This investigation was carried out to evaluate the characteristics of a Francis water turbine. Several variations of inlet valve openings of the turbine were tested to determine the effects of changes in rotational speed of runner on turbine performance. The method used in this study was experimental measurement using a test rig installation in Diponegoro University. The results found that discharge was not change significantly with increasing speed. The torque decreases as the turbine rotational speed increases. The break horse power (BHP) and efficiency curves are nearly identical. Both BHP and efficiency increase when speed are increased until the maximum condition is reached, then from this maximum condition, as speed increase, the BHP and efficiency gradually decrease.
The mechanical properties of grey cast irons can be modified with alloying elements. Cr and Cu have been known as elements that can improve tensile strength of grey cast irons. The improvement of tensile strength can be influence of fatigue strength. The goal of this research is to study the effect of alloying Cr and Cu on the fatigue strength. Four materials of grey cast irons have been conducted to high cycle fatigue (HCF) testing on the rotating bending machine. The first material is grey cast irons without added Cr and Cu, and the other have added. The percentages of Cr have been added are 0,23% wt, 0,32%wt and 0,47%wt and Cu 0,6%wt to 0,7%wt. The metallography examinations and tensile test also have been conducted. The results of this research are the material has the same microstructure. The microstructures of its materials are pearlitic grey cast irons with graphite type VII, distribution A and size of graphite 3-5. The tensile, endurance and fatigue strength of materials, which added Cr and Cu significantly increasing, compared with base materials. The tensile strength rose from 191MPa to 232MPa and the endurance strength raised from 94 MPa to 110MPa. However three modified materials, which added Cr and Cu has the same effects.
This study is aimed to investigate loaded and unloaded foot area ratio (RFA, ratio of foot area) as special tests for the basis of clinical examination of flat foot and healthy foot. Type of foot is determined by Cavanagh’s arch indexes (AI) which is the ratio between mid foot area to entire footprint area excluding the toes. Type of foot is called high arch when AI<0.21, normal/healthy foot when 0.26>AI≥0.21 and flat foot when AI>0.26. The entire loaded foot and footprint area for evaluating AI derived from a digital footprint is modified from document scanner, while the entire unloaded foot area derived from a 3D scanner. One hundred and two healthy students (87 males and 15 females, average aged 20 years and average BMI 22.51 kg/m 2 ) is asked voluntarily for doing footprint and scan. From 102 subjects found 63 participants identified as flat foot and 31 subjects are healthy feet. This study proves that the higher the value of AI the higher the value of RFA and foot type can be predicted by the value of RFA. For type of foot is high arch RFA<0.49, for healthy foot 0.55>RFA≥0.49 and for flat foot RFA>0.55.
In the predescor research its known that easy crack on the brake drum produced by small foundry industry is caused by grey cast iron which used has low tensile strength. The improvement of the tensile strength succesfully done with added Cr and Cu at specielics percentages. Its known that on the operation, the brake drum subjected to dynamical loading. It is necessary to know the behavior of improving material due dynamical loading. Its can be use to predicted the brake drum from fatigue failure.
In these researches 4 kinds of grey cast irons with different chemical composition have been tested. The material is base material (FC20) and 3 kind material with different percentage of Cr and Cu. The percentages of Cr have been added are 0,23%, 0,32% and 0,47% and Cu between 0,67% until 0,7%. The steps of these research are casting of test bar, specimens preparations and testing. The kinds of testing are chemical compotition testing, metallography testing, hardness testing, tensile testing, high cycle fatigue testing and fractography.
From metallography testing it known that the microstructure of material are pearlitics grey cast iron with type of graphite VII (flake graphite), A distributions and size of graphite 3-5. From mechanical properties testing its known that hardness, tensile strength, endurance strength and fatigue strength of improving material significantly raising. However, 3 modified chemical compotition of grey cast iron not significantly different. The raising of tensile strength is 20% from 191MPa to I32MPa and the raising of endurance strength is 17% from 94MPa to 110MPa.
Dalam penelitian sebelumnya diketahui bahwa penyebab mudah retaknya tromol bus/truk produk industri kecil adalah rendahnya kekuatan tank besi cor kelabu yang digunakan. Upaya meningkatkan kekuatan tariknya berhasil dilakukan yaitu dengan menambahkan unsur kromium dan tembaga sampai persentase tertentu. Seperti telah diketahui pada saat beroperasi beban yang bekcrja pada tromol rem merupakan beban dinamis. Oleh karena itu perilaku besi cor kelabu yang telah dikembangkan tersebut perlu diteliti. Hal ini dimaksudkan untuk dapat memperkirakan kekuatan tromol rem terhadap kegagalan lelah yang disebabkan oleh beban dinamis.
Pada penelitian ini telah dilakukan pengujian terhadap 4 macam besi cor kelabu dengan komposisi kimia yang berbeda. Material yang diuji adalah base material yaitu FC20 dan 3 macam modifikasi komposisi kromium dan tembaga. Besamya unsur Cr yang ditambahkan adalah 0,23%, 0,32% dan 0,47% dan unsur Cu antara 0,67 sampai 0,7%. Tahap-tahap penelitian dimulai dari pengecoran batang uji, penyiapan spesimen uji dan pengujian. Jenis pengujian yang dilakukan adalah pengujian komposisi kimia, metalografi, kekerasan, tank, lelah siklus tinggi dan fraktografi.
Dad pengujian yang telah dilakukan diperoleh bahwa struktur mikro 4 besi cor kelabu yang diuji adalah pearlitik dengan tipe grafit VII, distribusi A dan ukurannya 3-5. Dan pengujian sifat mekanik diperoleh terdapat peningkatan kekerasan, kekuatan tank dan ketahanan lelah yang sangat signifikan antara besi cor kelabu yang dipadu dengan yang tidak. Meskipun demikian Ice 3 besi cor kelabu yang dipadu tersebut menunjukkan sifat mekanik yang same. Peningkatan kekuatan tank yang diperoleh sebesar 20% yaitu dari 191MPa menjadi 232MPa dan ketahanan lelahnya sebesar 17% yaitu dari 94MPa menjadi 110MPa. Basil pengujian lelah siklus tinggi yang dilakukan menunjukkan bahwa material yang dipadu selain memiliki ketahanan letah yang tinggi juga memiliki kekuatan lelah yang lebih tinggi pula.
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