Volume- 7 Issue- 1 August 2019 0 7 , 6 MIST JOURNAL OF SCIENCE AND TECHNOLOGY THE ANNUAL TECHNICAL JOURNAL OF MILITARY INSTITUTE OF SCIENCE AND TECHNOLOGY Volume-7 Issue-1 August 2019 MIST, Mirpur Cantonment, Dhaka-1216, Bangladesh i EDITORIAL BOARD Chief Patron Major General Md Wahid-Uz-Zaman, ndc, aowc, psc, te Commandant, MIST Editor-in-Chief Colonel Molla Md. Zubaer, te A/Director Research and Development, MIST Editor Lieutenant Colonel Muhammad Sanaullah, psc, Engrs General Staff Officer-1 (Research), MIST Associate Editors Major Md Mohammad Shawkat Ali, Sigs Major Md Manwarul Haq, PhD, AEC Major Md Ferdausur Rahman, PhD, AEC Assistant Professor Selin Yasmin Editorial Advisors Brig Gen Md. Wahidul Islam, SUP, ndc, psc Director Academic and Dean Faculty CE, MIST Colonel M Mahmudul Hassan Director Administration, MIST Colonel Md Habibul Huq, psc Colonel Staff, MIST Proof Readers Md Morshed Mahmud – SAE (Drafting) Nurun Naher – SAE (Drafting) Disclaimer The analysis, opinions and conclusions expressed or implied in this Journal are those of the authors and do not necessarily represent the views of the MIST, Bangladesh Armed Forces or any other agencies of Bangladesh Government. Statements of fact or opinion appearing in MIST Journal are solely those of the authors and do not imply endorsement by the editors or publisher. ISSN: 2224-2007 Initial Submission Initial Submission of manuscripts and editorial correspondence should be sent to the MIST, Mirpur Cantonment, Dhaka-1216, Bangladesh. Tel: 88 02 8034194, FAX: 88 02 9011311, should consult the Notes for contributions at the back of the Journal before submitting their final draft. The editors cannot accept responsibility for any damage to or loss of manuscripts. Subscription Rate (Single Copy) Individuals : BDT 300 / USD 05 (including postage) Institutions : BDT 375 / USD 08 (including postage) Published by Military Institute of Science and Technology, Bangladesh All rights reserved. No part of this publication may be reproduced, stored in retrieval system, or transmitted in any form, or by any means, electrical, photocopying, re¬cording, or otherwise, without the prior permission of the publisher. Designed and Published by: Research and Development Wing, MIST ii FOREWORD Efficiency and Effective contribution to the nation by a degree awarding institution is adjudicated considering the innovative and fundamental research activities carried out by that institution. No one can deny the impact of research in development of critical thinking, creativity, problem solving, self-confidence and intellectual independence of students and teachers as well. MIST Journal of Science and Technology pictures the fundamental contributions in research work on global and local interests related to science and Technology. MIST, a growing academic institution is focused in the field of developing quality technical education and research to match up itself with other renowned Engineering Institutions at home and abroad. It has widened its effort to increase the number of PhD faculty members in all the engineering departments presently under it. MIST maintains a constant link with domestic industries and entrepreneurs for hands-on training of graduates. MIST Journal of Science and Technology pictures the fundamental contributions in research work on global and local interests related to science and Technology. A good number of selected works has been published in this Journal. I firmly believe that the readers will benefit from this Journal. I congratulate all the authors who have contributed to this journal. My special thanks to the editorial board and associated personnel for their relentless efforts in publishing the current issue of the journal, "MIST Journal of Science and Technology". May Almighty Allah bless us all in the pursuit of the motto of the institute, "Technology for Advancement" with His boundless blessings and adorn MIST as "Center of Excellence". Major General Md Wahid-Uz-Zaman, ndc, aowc, psc, te Commandant Military Institute of Science and Technology and Chief Patron, MIST Journal of Science and Technology iii EDITORIAL Research activity engages and empowers students in hands on learning and also provides effective career preparation which promotes interest in graduate education as well. MIST being one of the leading engineering institutions, patronizes multifarious research activities at all engineering departments related to national and international issues. The scope of the journal covers the full range of research, evaluation, design, operations and functioning of all engineering disciplines. Research activities provides platform and empowers faculty members and students for effective career preparation in engineering field. MIST always promotes research works in applied science and Technology and this Journal publishes fundamental, objective and innovative research works from writers of different universities and institutions from home and abroad. I express my deepest gratitude to Major General Md Wahid-Uz-Zaman, ndc, aowc, psc, te, the Chief Patron of MIST journal of Science and Technology for his invaluable and dynamic guidance during editorial period of volume-7, Number-1, August 2019 issue. I must mention the hard work and relentless support of members of the editorial board. I also express sincere thanks to the advisory board for their whole-hearted cooperation in publishing the journal. I believe this publication will raise the interest among the learned readers in relevant fields. Colonel Molla Md. Zubaer, te Acting Director Research and Development Wing Military Institute of Science and Technology and Editor in Chief, MIST Journal of Science and Technology iv ISSN 2224-2007 1 THE NULL EFFECT OF CROSS SECTIONS OTHER THAN THE MAXIMUM PITTED CROSS SECTION ON STRENGTH REDUCTION OF AGED MARINE PLATES SUBJECTED TO UNIAXIAL TENSILE LOADING Commodore M Munir Hassan (Retd)(1), Tasmia Hoque(2) and Lieutenant Colonel Muhammad Rabiul Islam, PhD(3) 1. Professor, Department of Naval Architecture and Marine Engineering Military Institute of Science and Technology, Dhaka, E-mail: Bangladesh [email protected] 2. Lecturer, Department of Naval Architecture and Marine Engineering Military Institute of Science and Technology, Dhaka E-mail: Bangladesh [email protected] 3. Instructor Class-A, Department of Naval Architecture and Marine Engineering Military Institute of Science and Technology, Dhaka E-mail: Bangladesh [email protected] ABSTRACT It is of essential importance to predict the strength reduction due to pitting corrosion for a proper condition assessment of aged ships. The crucial location of maximum pitting as well as the heavy unevenness of the metal surface creates difficulties for the surveyors to perform the survey. Empirical formula based on statistical data can assess the strength reduction due to pitting on the basis of damage intensity where the strength reduction is only a function of maximum pitted cross section. In this study, the formula is established again by nullifying the effect of other cross sections on the strength reduction except the maximum pitted cross section. This null effect of less pitted cross sections will increase the surveyors’ confidence to concentrate only on the maximum pitted cross section. A series of finite element analysis is carried out where MSC NASTRAN nonlinear implicit analysis code has been used in large deformation analysis of two different pitted marine steel rectangular plate samples. The pitting patterns of different intensity used in this study were generated by other researchers using a probabilistic corrosion model. Key words: Strength Reduction, Pitting Corrosion, MSC NASTRAN, Nonlinear Implicit Analysis, Probabilistic Cor- rosion Mode 1.0 INTRODUCTION Corrosion wastage is a prominent cause of age related deterioration of steel structures. Metal Condition assessment is a very important scheme as degrades locally in pit forms reducing strength and many vessels are removed from service before reaching deformability, which are main salient features for the end of their designed life. A Condition Assessment integrity of steel structures. For a proper condition Program is aimed at determining and assessing the assessment of aging ships, it is of essential importance actual technical condition of hull and/or machinery, to predict the strength and absorbing energy during electrical installation and cargo related systems at a collapse and/or fracture of corroded plate [1]. given point of time by surveys and investigations. According to Nakai et al. [2] it is very important to The purpose of a Condition Assessment Survey is to investigate the effect of corrosion wastage not only analyze the remaining strength of the hull structure. on overall strength but also on local strength. They MIST Journal of Science and Technology | Volume 7 | Issue 1 | August 2019 The Null Effect of Cross Sections other Than............. Cdre Munir, Tasmia Hoque and Lt Col Rabiul 2 have investigated shape of corrosion pit on a single In the current study the effect of cross sections other hull tanker and found circular cone shaped pit on hold than the maximum pitted cross section is nullified by frame of bulk carrier and spherical shaped pit on the selecting a part of total pitted surface which includes bottom shell of the tanker. The effect of corrosion the maximum pitted cross section. Here the length of is basically the geometric effect and chemistry does part is chosen as 20 mm [a random choice] [10mm not come into play [3]. It is thus of