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KAJI NUMERIK PENCEGAHAN PERTUMBUHAN RETAK DENGAN MENGGUNAKAN METODE MODIFIKASI BENTUK STOP-DRILLED HOLE (SDH) Dahlan, Hendery; Rusli, Meifal; Dwianda, Yudi
Media Mesin: Majalah Teknik Mesin Vol 18, No 2 (2017)
Publisher : Universitas Muhammadiyah Surakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar

ABSTRAKÂ Salah satu mekanisme kegagalan yang utama dalam aplikasi teknik atau komponen mesin adalah penjalaran retak kelelahan. Penjalaran retak ini biasanya dimulai dari titik-titik pada daerah yang mengalami konsentrasi tegangan yang tinggi. Oleh karena itu salah satu metode untuk menghambat penjalaran retak adalah Â mereduksi konsentrasi tegangan dimana salah satu metode yang digunakan adalah pemberian lubang di ujung retak atau dikenal dengan stop-drilled hole (SDH). Pada penelitian ini akan dikembangkan modifikasi bentuk model SDH. Pada dasarnya model yang dikembangkan ini adalah merubah bentuk pada sisi lubang agar tidak berbentuk lengkungan sehingga Â konsentrasi tegangan menurun di daerah tersebut. Pemodelan lubang yang dikembangkan pada peneltian ini adalah penggambungan dua lubang dan tiga lubang pada ujung retak. Pada penelitian ini akan dilakukan penghitungan faktor konsentrasi tegangan untuk variasi jari-jari lubang yang diberikan. Dari penelitian yang telah dilakukan dapat disimpulkan bahwa pemberian dua lubang dan tiga lubang pada ujung cetak tersebut dapat mereduksi faktor konsentrasi tegangan dengan signifikan, nilai faktor konsentrasi tegangan antara dua lubang dan tiga lubang tidak berbeda signifikan terutama dengan meningkatnya nilai jari-jari lubang. Sementara itu, faktor konsentrasi tegangan tetinggi terjadi pada daerah perubahan geometri pada lubang untuk pemberian dua atau tiga lubang, akan tetapi faktor konsentrasi tegangannya masih cukup rendah jika dibandingkan dengan pemberian satu lubang.Â Kata Kunci : Konsentrasi Tegangan, Penjalaran Retak, Stop-Drilled Hole (SDH) Â Â ABSTRACTÂ One of the major failure mechanisms in engineering applications or machine components is the propagation of fatigue cracking. The spreading of these cracks usually are started from the points on the regions that areÂ experiencing high stress concentrations. Therefore, one of the method to inhibit this crack propagation is reducing the stress concentration in which one of the used methodsÂ is the provision of a hole at the end of a crack or known as a stop-drilled hole (SDH). In this research will be developedÂ a modification form of SDH model. Basically the developed model is changing the shape on the hole side so there are not forming of the curve so that the stress concentration decreases in this area. The developed hole model in this research is the binding of two holes and three holes at the crack tip. This research will be calculated the stress concentration factor for variation of given hole radius. From the research that has been done, it can be concluded that the two holes and three holes on the tip of the crack can reduce the stress concentration factor significantly. Moreover,Â the value of the stress concentration factor between two holes and three holes is not significantly different, especially with the increment of the hole radius. Meanwhile, the high stress concentration factor occured in the geometrical change area of the hole for two or three holes, but the stress concentration factor is still quite low when compared to the one hole.Â Keywords : Stress Concentration, Crack Propagation, Stop-Drilled Hole (SDH)

THE EFFECT OF CRITICAL TRACTION IN COHESIVE ZONE MODEL FOR FATIGUE CRACK GROWTH RETARDATIO Dahlan, Hendery
Media Mesin: Majalah Teknik Mesin Vol 17, No 2 (2016)
Publisher : Universitas Muhammadiyah Surakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar

A cohesive zone model for simulation of fatigue crack growth is presented. The cohesive zone model is one of many alternative approaches used to simulate fatigue crack growth. The model incorporates a relationship between cohesive traction and separation in the zone ahead of a crack tip. The model introduces irreversibility into the constitutive relationships by means of damage accumulation with cyclic loading. The traction-separation relationship underpinning the cohesive zone model is not required to follow a predetermined path, but is dependent on irreversibility introduced by decreasing a critical cohesive traction parameter. The approach can simulate fatigue crack growth without the need for re-meshing and caters for single overloading. This study shows the retardation phenomenon occurring in elastic plastic-materials due to single overloading. Increasing the value of critical cohesive traction increases the extent of plastic zone at the crack tip which causes the fatigue crack growth to retard. Plastic materials can generate a significant plastic zone at the crack which is shown to be well captured by the cohesive zone model approach.

KAJI EKSPERIMETAL PENGHAMBAT PENJALARAN RETAK DENGAN MENGGUNAKAN PENGAKU Dahlan, Hendery; Dwianda, Yudi; Rusli, Meifal
Media Mesin: Majalah Teknik Mesin Vol 19, No 2 (2018)
Publisher : Universitas Muhammadiyah Surakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar

Salah satu penyebab retak muncul di struktur biasanya berawal pada daerah yang mengalami konsentrasi tegangan yang tinggi. Jika pembebanan terus dilakukan maka retak akan terus tumbuh dan menjalar sehingga menyebabkan terjadinya kegagalan. Oleh karena itu, diperlukan suatu cara atau metode yang efektif untuk menahan laju pertumbuhan retak sebelum kegagalan terjadi. Pada penelitian ini akan dilakukan kajian secara eksperimental pengaruh lasan, dimensi pengaku dan jumlah pengaku terhadap beban kritis sebelum retak menjalar. Dari penelitian yang telah dilakukan dapat disimpulkan bahwa pengaku yang diberikan sangat efektif mempengaruhi laju perambatan retak. Selain itu, dimensi pengaku mempengaruhi penghambatan penjalaran retak dimana semakin besar dimensi pengaku maka rata rata beban kritis yang dibutuhkan untuk retak mulai menjalar semakin besar. Sementara itu kualitaspengelasan pada retak sangat mempengaruhi penghambatan retak untuk menjalar.

Pengaruh Thermal Shock Terhadap Kekuatan Tarik dan Bending KompositResinBerpenguat Serat Rami Rozi Saferi; Hendery Dahlan; Mulyadi Bur Mulyadi Bur
Jurnal Energi Dan Manufaktur Vol 8 No 2 (2015): Oktober 2015
Publisher : Department of Mechanical Engineering, University of Udayana

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (780.674 KB)

Abstrak:Perkembanganteknologi komposit saat ini sudah mulai mengalami pergeseran, dari bahan komposit berpenguat serat sintesismenjadi bahan komposit berpenguat serat alam. Serat alam rami (Boehmeria Nivea) memiliki peluang untukdikembangkan sebagai media penguatan pada resin polimer. Tujuan dari penelitian ini untuk mengetahui perubahan kekuatan tarik dan bending kompositresinberpenguat serat ramiakibat pengaruh lingkungan. Dalam penelitian ini digunakan serat ramipintalan dengan diameter 1.5 mm yang ditenun manual dan matriks polyester jenis resin bening.. Fraksi volume serat dan resin yang digunakan9% dan 91%.Tenunan serat divariasikan baik dengan perlakuan NaOH 20% maupun tanpa perlakuan alkali. Komposit dipanaskan di dalam oven listrik pada temperatur 1000C selama 1 jam, kemudian dilakukan pendinginan dengan merendam komposit pada ????????2???????? dengan variasi siklus thermal shock 5, 10, 15, dan 20. Spesimen uji tarik dan uji bending dibuat berdasarkan ASTM D638 dan ASTM D790-03.Hasil penelitian menunjukkan Kekuatan tarik dari komposit resin berpenguat serat rami dengan perlakuan NaOH 20% rata-rata turun 25,66 % dari kekuatan tarik maksimum sebesar 38.4 MPa dan turun 24.51% dari kekuatan tarik maksimum sebesar 29.08 MPa untuk serat tanpa perlakuan NaOH akibat perlakuan thermal shock. Kekuatan bending dari komposit resin berpenguat serat rami dengan perlakuan NaOH mengalami penurunan rata-rata 14.14 % dari kekuatan bending maksimum sebesar 75.08 MPa dan mengalami penurunan 17.34% dari kekuatan bending maksimum sebesar 49.57 MPa untuk serat tanpa perlakuan NaOH akibat pengaruh thermal shock.Bentuk patahan spesimen komposit setelah diberikan perlakuan thermal shock menunjukkan semakin getasnya stuktur dari komposit dan semakin rapuhnya serat rami baik dengan maupun tanpa perlakuan NaOH Kata Kunci: Komposit, rami, thermal shock, sifat mekanik.Abstract:The recent composite technology has changed from synthetic to natural fibre-reinforced composite. Natural fibre Boehmeria Nivea (rami) is one of the promising reinforced medium to polymer resin. The objective of the present work is to investigate the tensile and bending strengths of the boehmeria nivea fibre-reinforced resin composite. The present research used a 1.5 mm diameter of woven boehmeria nivea fibre and a transparent resin of polyester matrix. The volume fraction of the fibre and resin were 9% and 91%, respectively. The woven fibre was varied with 20% NaOH and without alkali treatment. The composite was heated in electrical oven at 1000 oC during 1 hour, and then cooled by immersing the composite in the water at various cycle of thermal shock 5, 10, 15, and 20, respectively. The specimen for tensile and bending test was made according to ASTM D638 and ASTM D790-03. The results showed that the tensile strength of the boehmeria nivea fibre-reinforced composite with NaOH 20% treatment decreased 25,66% by average from the maximum tensile strength 38.4 MPa. Meanwhile the tensile strength that of without NaOH treatment decreased 24,51% from the maximum tensile strength 75,08 MPa. Those of bending strength of the tested composite also decreased 14,14% from the maximum value 75,08 MPa; and decreased 17,34% from the maximum bending strength 49,57 MPa, respectively. The fracture shape of the specimen showed both the brittle structure of the composite and the fragile fibre on both with and without treatment. KeyWords: Composite, rami, thermal shock, mechanical properties

KAJI EKSPERIMETAL PENGHAMBAT PENJALARAN RETAK DENGAN MENGGUNAKAN PENGAKU Hendery Dahlan; Yudi Dwianda; Meifal Rusli
Media Mesin: Majalah Teknik Mesin Vol 19, No 2 (2018)
Publisher : Program Studi Teknik Mesin, Universitas Muhammadiyah Surakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.23917/mesin.v19i2.7498

Salah satu penyebab retak muncul di struktur biasanya berawal pada daerah yang mengalami konsentrasi tegangan yang tinggi. Jika pembebanan terus dilakukan maka retak akan terus tumbuh dan menjalar sehingga menyebabkan terjadinya kegagalan. Oleh karena itu, diperlukan suatu cara atau metode yang efektif untuk menahan laju pertumbuhan retak sebelum kegagalan terjadi. Pada penelitian ini akan dilakukan kajian secara eksperimental pengaruh lasan, dimensi pengaku dan jumlah pengaku terhadap beban kritis sebelum retak menjalar. Dari penelitian yang telah dilakukan dapat disimpulkan bahwa pengaku yang diberikan sangat efektif mempengaruhi laju perambatan retak. Selain itu, dimensi pengaku mempengaruhi penghambatan penjalaran retak dimana semakin besar dimensi pengaku maka rata rata beban kritis yang dibutuhkan untuk retak mulai menjalar semakin besar. Sementara itu kualitaspengelasan pada retak sangat mempengaruhi penghambatan retak untuk menjalar.

KAJI NUMERIK PENCEGAHAN PERTUMBUHAN RETAK DENGAN MENGGUNAKAN METODE MODIFIKASI BENTUK STOP-DRILLED HOLE (SDH) Yudi Dwianda; Hendery Dahlan; Meifal Rusli
Media Mesin: Majalah Teknik Mesin Vol 18, No 2 (2017)
Publisher : Program Studi Teknik Mesin, Universitas Muhammadiyah Surakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.23917/mesin.v18i2.5239

ABSTRAK Salah satu mekanisme kegagalan yang utama dalam aplikasi teknik atau komponen mesin adalah penjalaran retak kelelahan. Penjalaran retak ini biasanya dimulai dari titik-titik pada daerah yang mengalami konsentrasi tegangan yang tinggi. Oleh karena itu salah satu metode untuk menghambat penjalaran retak adalah mereduksi konsentrasi tegangan dimana salah satu metode yang digunakan adalah pemberian lubang di ujung retak atau dikenal dengan stop-drilled hole (SDH). Pada penelitian ini akan dikembangkan modifikasi bentuk model SDH. Pada dasarnya model yang dikembangkan ini adalah merubah bentuk pada sisi lubang agar tidak berbentuk lengkungan sehingga konsentrasi tegangan menurun di daerah tersebut. Pemodelan lubang yang dikembangkan pada peneltian ini adalah penggambungan dua lubang dan tiga lubang pada ujung retak. Pada penelitian ini akan dilakukan penghitungan faktor konsentrasi tegangan untuk variasi jari-jari lubang yang diberikan. Dari penelitian yang telah dilakukan dapat disimpulkan bahwa pemberian dua lubang dan tiga lubang pada ujung cetak tersebut dapat mereduksi faktor konsentrasi tegangan dengan signifikan, nilai faktor konsentrasi tegangan antara dua lubang dan tiga lubang tidak berbeda signifikan terutama dengan meningkatnya nilai jari-jari lubang. Sementara itu, faktor konsentrasi tegangan tetinggi terjadi pada daerah perubahan geometri pada lubang untuk pemberian dua atau tiga lubang, akan tetapi faktor konsentrasi tegangannya masih cukup rendah jika dibandingkan dengan pemberian satu lubang. Kata Kunci : Konsentrasi Tegangan, Penjalaran Retak, Stop-Drilled Hole (SDH) ABSTRACT One of the major failure mechanisms in engineering applications or machine components is the propagation of fatigue cracking. The spreading of these cracks usually are started from the points on the regions that are experiencing high stress concentrations. Therefore, one of the method to inhibit this crack propagation is reducing the stress concentration in which one of the used methods is the provision of a hole at the end of a crack or known as a stop-drilled hole (SDH). In this research will be developed a modification form of SDH model. Basically the developed model is changing the shape on the hole side so there are not forming of the curve so that the stress concentration decreases in this area. The developed hole model in this research is the binding of two holes and three holes at the crack tip. This research will be calculated the stress concentration factor for variation of given hole radius. From the research that has been done, it can be concluded that the two holes and three holes on the tip of the crack can reduce the stress concentration factor significantly. Moreover, the value of the stress concentration factor between two holes and three holes is not significantly different, especially with the increment of the hole radius. Meanwhile, the high stress concentration factor occured in the geometrical change area of the hole for two or three holes, but the stress concentration factor is still quite low when compared to the one hole. Keywords : Stress Concentration, Crack Propagation, Stop-Drilled Hole (SDH)

THE EFFECT OF CRITICAL TRACTION IN COHESIVE ZONE MODEL FOR FATIGUE CRACK GROWTH RETARDATIO Hendery Dahlan
Media Mesin: Majalah Teknik Mesin Vol 17, No 2 (2016)
Publisher : Program Studi Teknik Mesin, Universitas Muhammadiyah Surakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.23917/mesin.v17i2.2883

A cohesive zone model for simulation of fatigue crack growth is presented. The cohesive zone model is one of many alternative approaches used to simulate fatigue crack growth. The model incorporates a relationship between cohesive traction and separation in the zone ahead of a crack tip. The model introduces irreversibility into the constitutive relationships by means of damage accumulation with cyclic loading. The traction-separation relationship underpinning the cohesive zone model is not required to follow a predetermined path, but is dependent on irreversibility introduced by decreasing a critical cohesive traction parameter. The approach can simulate fatigue crack growth without the need for re-meshing and caters for single overloading. This study shows the retardation phenomenon occurring in elastic plastic-materials due to single overloading. Increasing the value of critical cohesive traction increases the extent of plastic zone at the crack tip which causes the fatigue crack growth to retard. Plastic materials can generate a significant plastic zone at the crack which is shown to be well captured by the cohesive zone model approach.

IMPLEMENTASI TEKNOLOGI WASTAFEL TANPA SENTUH DI RUMAH SAKIT KOTA PADANG DALAM RANGKA MEMUTUS MATA RANTAI COVID-19 Zaini Zaini; Syarkawi Syamsuddin; Wisnu Joko Wulung; Purnawan Purnawan; Hendery Dahlan; Wisnel Wisnel; Denny Herald
Jurnal Hilirisasi IPTEKS Vol 3 No 4 (2020)
Publisher : LPPM Universitas Andalas

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25077/jhi.v3i4.466

The public's lack of concern for health protocols is directly proportional to the increase in the number of people affected by the Covid-19 virus. This condition worsens when public facilities such as available hand washing equipment tend to be less hygienic because there is still physical contact during the hand washing process, so there is a great potential risk of spreading the Covid-19 outbreak in the community en masse. Therefore an innovation was made in the form of a touchless hand washing device equipped with sensors to replace the function of water taps and manual liquid soap containers. The target audience of this activity is the people in the hospital environment of Padang City. This activity is carried out in two stages, namely the first stage to design tools and the second stage in the form of procurement of tools as well as outreach to the people of Padang City who visit the hospital regarding the introduction and how to use hand washing tools without touch as well as demonstrating to the community with the assistance of the hospital about how to wash hands properly and correctly according to health protocols.

IMPLEMENTASI PENGGUNAAN APLIKASI ANDROID SEBAGAI SELF-ASSESSMENT DAN MEDIA INFORMASI COVID-19 DI PUSKESMAS DADOK DAN KELURAHAN KAMPUNG LAPAI NANGGALO KOTA PADANG Trisfa Augia; Mery Ramadani; Hendery Dahlan; Rizki Ridhatul Tani; Fauziah Fauziah
Jurnal Hilirisasi IPTEKS Vol 3 No 4 (2020)
Publisher : LPPM Universitas Andalas

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25077/jhi.v3i4.476

Coronavirus Disease 2019 (COVID-19) is an infectious disease caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). SARS-CoV-2 is a new type of coronavirus that has never been previously identified in humans. Indonesia reported its first case of COVID-19 on March 2, 2020 and the number continues to grow until now. Until October, 15 2020 the Ministry of Health reported 349,160 confirmed cases of COVID-19 with 12,268 deaths. The COVID-19 Self-Assessment application can help screening of individual and health workers to accelerate case finding and make it easier for health workers to provide curative efforts. Socialization of the COVID-19 Self-Assessment Application in coordination with the Public Health Center Dadok Tunggul Hitam and Kelurahan Kampung Lapai. Activities included introduction, installation, implementation, and monitoring and evaluation of application usage. Participants installed the application on an Android device and implemented the application enthusiastically. It is hoped that this application can make it easier for community to access information related to COVID-19 and carry out screening independently.

PENERAPAN APLIKASI KONSELING PENYAKIT DIARE KLINIK SANITASI DI PUSKESMAS Trisfa Augia; Hendery Dahlan
HUMAN CARE JOURNAL Vol 5, No 1 (2020): Human Care Journal
Publisher : Universitas Fort De Kock

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.32883/hcj.v5i1.646

Diarrheal disease is an environmental-based disease that is still a public health problem in Indonesia due to it is a major contributor to the death of children, especially children under five. This disease is expected to be prevented through optimal counseling efforts at the public health center. However, human resources and limited time are major issues that cause counseling activities still not optimal. Therefore, an android-based diarrhea counseling application was developed using Kobo ToolBox®. This study aims to determine the accessibility, effectiveness, and efficiency of the application in conducting counseling, particularly identifying problems and recommendations for patients. The research method used descriptive quantitative method and was carried out in two health centers in Padang. The results of this study note that 88.89% of respondents expressed this application was easily accessed and can be used offline or online, 82.22% of respondents said this application was easy to operate and helped the implementation of counseling, 93.33% agreed this application requires a short time, the contents of the application referred to regulations, and questions and application menus are easy to understand and 96.67% of respondents said the application display was by needs. It can be concluded that this application helps health workers in conducting diarrhea counseling and is expected to be developed for other environmental-based diseases

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