Engineering Code Research Articles

Buckling of Cylindrical Steel Tanks With Oblique Body Imperfection Under Uniform External Pressure

Shell structures are built using a number of welded curved panel parts. Hence, some geometrical imperfections emerge. These imperfections have a direct impact on structural behavior of shells during the external compressive loading. In this research, a field study was accomplished on the implementation of the storage tanks in a refinery site, and then the resulted imperfections were identified and categorized. The survey of imperfections revealed that imperfection resulted from deviation with respect to the vertical direction has the highest number in tank bodies. This imperfection experimentally modeled, and the buckling behavior of these tanks was evaluated under uniform external pressure. The cylindrical tanks were examined using finite element analysis, and results obtained were compared with experimental results. Investigation of finding results demonstrated that such imperfection has a significant role in reducing the number of circumferential waves in body of the tanks under uniform external pressure. Comparing the results obtained by estimation, American Society of Mechanical Engineers (ASME) code, experimental research, and finite element method (FEM) represented a considerable difference in the amount of buckling load. Results show that tanks with oblique body imperfections exhibit high initial strength against buckling due to the uniform external pressure.

Contextualizing the Code: Ethical Support and Professional Interests in the Creation and Institutionalization of the 1974 IEEE Code of Ethics

ABSTRACTIn many engineering ethics classes, codes of ethics are presented as if they are self-evident yardsticks for gauging ethical decisions in engineering. In this article, we argue that focusing solely on the content of ethics codes without examining the professional contexts in which codes are created – and are made meaningful – misses important opportunities to understand the engineering profession's ethical aspirations and how such codes affect engineers’ professional identities. Our analysis demonstrates a ‘contextualized reading’ of an engineering code of ethics through a historical case study consisting of two successive episodes: In the first episode, we show how engineers’ yearning for ethical support and their competing interpretations of professional interests catalyzed the creation of the first Institute of Electrical and Electronics Engineers (IEEE) Code of Ethics in 1974; the second episode of the case documents the complex institutional processes followed by IEEE members to ensure compliance with the code of ethics in professional practice. For engineering studies scholars, tracing the historical context of codes of ethics offers a pathway to understand engineers’ ‘existential struggles’ – that is, how engineers responded to major challenges and crises as a profession – at a particular historical moment. For engineering ethics educators, revealing how ethics codes operate in the institutional context of professional organizations prepares students to appreciate the ethical horizon of the profession they inherit as well as to redirect or expand that horizon moving into the future.

Development and Preliminary Verification of Reactor Shielding Design Code cosSHIELD of COSINE Code Package

COre and System INtegrated Engine for design and analysis (COSINE), is an integrated nuclear engineering code package, which is developed by State Nuclear Power Software Development Center (SNPSDC) in China. Reactor radiation shielding is an indispensable part of nuclear power plant design. According to relevant regulations and guidance, and based on the discrete ordinate method, the reactor shielding design code cosSHIELD was developed and verified preliminary using TEKEDA and Kobayashi benchmark. The results show that cosSHIELD can solve the critical and stationary source problem very well, in addition mitigate the ray effects efficiently.

A Postassessment Test of 100,000 h Creep Rupture Strength of Grade 91 Steel at 600 °C

Predictions as to 105 h creep rupture strength of grade 91 steel have been made recently. The predicted values are examined with long-term creep rupture data of the steel. Three creep rupture databases were used in the predictions: data of tube products of grade 91 steel reported in National Institute for Materials Science (NIMS) Creep Data Sheet (NIMS T91 database), data of T91 steel collected in Japan, and data of grade 91 steel collected by an American Society of Mechanical Engineers (ASME) code committee. Short-term creep rupture data points were discarded by the following criteria for minimizing overestimation of the strength: selecting long-term data points with low activation energy (multiregion analysis), selecting data points crept at stresses lower than a half of proof stress (σ0.2/2 criterion), and selecting data points longer than 1000 h (cutoff time of 1000 h). In the case of NIMS T91 database, a time–temperature parameter (TTP) analysis of a dataset selected by multiregion analysis can properly describe the long-term data points and gives the creep rupture strength of 68 MPa at 600 °C. However, TTP analyses of datasets selected by σ0.2/2 criterion and cutoff time of 1000 h from the same database overestimate the data points and predict the strength over 80 MPa. Datasets selected by the same criterion from the three databases provide similar values of the strength. The different criteria for data selection have more substantial effects on predicted values of the strength of the steel than difference of the databases.

Mitigation of industrial hazards by water spray curtains

A Nowadays, the water spray curtain is recognized as a useful technique to mitigate major industrial hazards. It combines attractive features such as simplicity of use, efficiency and adaptability to different types of risks. In case of accidental toxic gas releases, the spray curtain may be used as a direct-contact reactor exchanging momentum, heat and mass with the gas phase. The cloud is diluted, warmed, and if toxic, some of its toxic content can be absorbed by the droplets to which chemical reactants can be added. In case of fire, water sprays can provide thermal shielding to maintain the integrity of storage tanks. The curtain behaves as a filter and can produce significant attenuation of the incident radiation that impinges on crucial structures such as petro-chemical storage tanks.Both of these applications have been thoroughly investigated at the von Karman Institute The outcome of these research projects is a comprehensive engineering code simulating on the one hand the forced dispersion, heating and physico-chemical inhibition of cold pollutant clouds and on the other hand the thermal shielding performance of a water curtain. The numerical approach is supported by laboratory (including wind tunnel tests) and field tests dedicated to investigate the effects of numerous operating parameters on the water spray curtain efficiency and to build a data base for model validation.The paper gives an overview of the main features of the modeling and on practical industrial applications with a special focus on the adequate water curtain operating conditions and the influence of environmental factors.

FEASIBILITY ASSESSMENT OF FLOOD DISASTER MITIGATION TECHNIQUES IN THE INDONESIAN CONTEXT

Flood in Indonesia, especially in Surabaya City has become a major and annually problem. Most of the mitigations focused on structural mitigation techniques such as river bank protection, river cleaning, and normalization or other reactive actions. Therefore, the problem still remaining exists and cause severe danger for the community lives. However, assessing some applied mitigation techniques from some countries' experiences are significant to identify the best strategies of flood mitigation techniques. The assessment process can be done not only on structural mitigation techniques but also on other techniques such as land use planning, warning system, engineering and building codes, insurance, new technology, emergency preparedness, and ecological mitigation. Combination among them may contribute for reducing and transferring risks of disaster which finally can minimize the impacts of the disaster to the communities

Structural assessment of a lattice tower for a small, multi-bladed wind turbine

This paper deals with a limit load assessment and preliminary experimental testing of a lattice-type steel tower used to support a newly designed, prototype small wind turbine having nine blades and a rotor diameter of 3.4 m. Small wind turbine and structural engineering codes of standards were followed with the purpose of implementing a system that meets European Union countries’ legislation. The supporting lattice tower structure was subjected to a full-scale load test. This test verified that the structure can withstand the design loads. The finite element software ANSYS Mechanical was used to model and analyse the actual structure, and to determine the possible failure modes and their associated load levels. The most probable mode of failure for such a structure was found to be elastic buckling of the main corner posts. A number of finite element lattice tower models utilising different modelling strategies and solution methods are presented and analysed. The paper highlights the importance of using non-linear analyses as opposed to linear analyses and gives recommendations on the most reliable available modelling technique. Computational analyses’ results are compared with measurements from a full-scale test on the tower structure.

A Reaffirmation of Fracture Toughness Requirements for ASME Section VIII Vessels for Service Temperatures Colder Than 77 K

Abstract To assure adequate fracture resistance of cryogenic pressure vessels designed to operate at a minimum design metal temperature (MDMT) colder than 77 K (−196 °C or −320 °F), current American Society of Mechanical Engineers (ASME) Code, Section VIII, Division 1, UHA-51 Impact Test rule requires that the weld metal (WM) meets or exceeds 0.53 mm (21 mils) lateral expansion at 77 K, i.e., LE77K ≥ 0.53 mm (21 mils), as determined using Charpy V-notch (CVN) impact testing. To the credit of this rule, cryogenic pressure vessels fabricated to date meeting the above requirement had continued to serve well—without any adverse incident—in numerous applications across the world, at cryogenic temperatures colder than 77 K. However, a critical examination of the underlying research which relied on a regression equation relating ratio of fracture toughness to yield strength obtained at 4 K, i.e., [KIc/YS]4K with LE77K, revealed that the technical basis for establishing the above requirement is metallurgically unsustainable. To successfully overcome this, the present research employed dimensional analysis and balancing of the previously published regression equations and proposed [KIc/YS]277K as a valid fracture resistance parameter applicable for MDMT 77 K and warmer, as well as MDMT colder than 77 K. Related efforts offered equivalent fracture resistance as an insightful concept, wherein the minimum fracture resistance parameter for a MDMT colder than 77 K is equated as a simple multiple of the minimum fracture resistance parameter at 77 K MDMT. Concluding efforts applied numerical analysis to the equivalent fracture resistance equation to reaffirm the current minimum 0.53 mm (21 mils) CVN LE77K requirement for WM when MDMT is colder than 77 K and to identify minimum required [KIc/YS]277K values for cryogenic service at MDMT 77 K and warmer, and MDMT colder than 77 K. Inherently, the use of [KIc/YS]277K as a fracture resistance parameter offers a tremendous benefit to cryogenic equipment manufacturers, particularly in schedule and cost savings, as LE, KIc, and YS measured at 77 K can be used to successfully assess the fracture resistance at MDMT 77 K and warmer, as well as MDMT colder than 77 K.

Remaining Fatigue Lives of Similar Surface Flaws in Accordance With Combination Rules

When multiple flaws are detected in structural components, the remaining lives of the components are estimated by fatigue flaw growth calculations using combination rules in fitness-for-service (FFS) codes. Many FFS codes provide combination rules for multiple flaws; however, these rules differ significantly among the various codes. Fatigue flaw growths for two similar adjacent surface flaws in a flat plate subjected to a cyclic tensile stress were obtained by numerical calculations using these different combination rules. In addition, fatigue flaw growths taking into account the interaction effect between the two similar flaws were conducted by the extended finite-element method (X-FEM). The calculation results show that the fatigue lives calculated by the X-FEM are close to those obtained by the American Society of Mechanical Engineers (ASME) Code. Finally, it is noted that the combination rule provided by the ASME Code is appropriate for fatigue flaw growth calculations.

Radiation Transport Calculation of the UGXR Collimators for the Jules Horowitz Reactor (JHR)

Jules Horowitz Reactor (JHR), a major infrastructure of European interest in the fission domain, will be built and operated in the framework of an international cooperation, including the development and qualification of materials and nuclear fuel used in nuclear industry. For this purpose UGXR Collimators, two multi slit gamma and X-ray collimation mechatronic systems, will be installed at the JHR pool and at the Irradiated Components Storage pool. Expected amounts of radiation produced by the spent fuel and X-ray accelerator implies diverse aspects need to be verified to ensure adequate radiological zoning and personnel radiation protection. A computational methodology was devised to validate the Collimators design by means of coupling different engineering codes. In summary, several assessments were performed by means of MCNP5v1.60 to fulfil all the radiological requirements in Nominal scenario (TEDE < 25µSv/h) and in Maintenance scenario (TEDE < 2mSv/h) among others, detailing the methodology, hypotheses and assumptions employed.

Is professional practice at risk following the Volkswagen and Tesla motors revelations?

With the world in economic crisis the headlong drive for efficiency and effectiveness together with resulting profit is the watchword. Such pressure might have resulted in real gains but has also led to unscrupulous or reckless actions. The tempering of such drive with ethical consideration is often neglected until there is a detrimental event causing public outcry which in turn places pressure on the actors to account for the reasons the event had occurred. This cause and effect map is commonplace. The Volkswagen emissions scandal and Tesla Motors public beta testing of the Autopilot software in their cars illustrate the drive for efficiency and effectiveness without proper ethical consideration. This paper focuses on the role of software engineers in such situations. An ethical analysis of the two cases is presented using the Software Engineering Code of Ethics and Professional Practice. The findings, together with previously published analyses, are used to draw general conclusions and recommendations about the efficacy of the software engineering profession.

Deterministic assessment of seismic risk in Constantine city, Northeast Algeria

Northern Algeria has experienced many destructive earthquakes throughout its history. The largest recent events occurred in El Asnam on October 10, 1980 (moment magnitude; Mw = 7.3), in Constantine on October 27, 1985 (surface-wave magnitude; Ms = 6.0), and in Zemmouri–Boumerdes on May 21, 2003 (Mw = 6.8). Because of the high population density and industrialization in these regions, the earthquakes had disastrous consequences and hence highlighted the vulnerability of Algeria to seismic events. To reduce seismic risk in Constantine, the capital city of East Algeria, we present a seismic risk scenario for this city, focusing on the vulnerability of the key historic areas of Coudia, Bellevue–Ciloc, and the Old City. This scenario allows us to assess the maximum ground acceleration using empirical attenuation laws, based on the following considerations: (a) the 1985 Constantine seismic event as an earthquake reference; (b) site effects related to regional geology; (c) damage to buildings, and (d) seismic vulnerability. This study shows the map of peak ground acceleration taking into account the effects of site lithology (Avib). We observe the strongest vibrations along the two rivers “Boumerzoug and Rhumel” and also, we note that the EC8 gives a good estimate acceleration in the image of the three studied areas (Bellevue–Ciloc, Coudia, and Old Town). By correlating with the geology, we observe an acceleration of 0.13 g in the neritic limestone of the rock (Old Town) something that fits with the value obtained 0.14 g (PGA) without taking into consideration the lithology. Moreover, according to the Algerian Earthquake Engineering Code (2003) (RPA), the Wilaya of Constantine is classified in the zone IIa (medium seismicity) with an acceleration data of 0.25 g. This study integrates geographic information system (GIS) data into risk models.

Undergraduate engineering students’ attitudes and perceptions towards ‘professional ethics’ course: a case study of India

ABSTRACT‘Professional Ethics’ has been offered as a compulsory course to undergraduate engineering students in a premier engineering institution of India. It was noticed that students’ perceptions and attitudes were frivolous and ornamental towards this course. Course instructors and institution authorities were motivated to find out the factors contributing to this awkwardness. For this purpose, a questionnaire was prepared and administrated to 336 students registered for the July–November 2014 semester. The study found two factors contributing to students’ indifference towards the Professional Ethics course. First, most of the students did not have self-interest to join the engineering programme, and while pursuing their study, they decided to switch to a different field upon completion of their engineering study. Second, students who desired to be engineers in their future believed that engineering code of ethics is not really referred to in most of the engineering jobs, and therefore Professional Ethics course is only meant for classroom discussions.

The Welded Joint Strength Reduction Factors of Modified 9Cr–1Mo Steel for the Advanced Loop-Type Sodium Cooled Fast Reactor

Creep strength enhanced ferritic (CSEF) steels including ASME Gr.91 are widely used in fossil power plants. In the advanced loop-type sodium-cooled fast reactor (SFR), modified 9Cr–1Mo steel (ASME Gr.91) is going to be adopted as a structural material. Modified 9Cr–1Mo steel was registered in the Japan Society of Mechanical Engineers (JSME) code as a new structural material for SFRs in the year 2012. The creep-rupture curve of the base metal of this steel was standardized using region splitting analysis method. According to this method, creep-rupture data were divided into two regions, high-stress and low-stress regimes, and those regions were individually evaluated by regression analyses with the Larson–Miller parameter (LMP). The difference in the creep failure mechanisms between the high-stress and low-stress regions was considered in this method. The boundary between these regions was half of the 0.2% proof stress of the base metal at the corresponding temperature. In the modified 9Cr–1Mo steel welded joint, creep strength may markedly degrade, especially in the long-term region. This phenomenon is known as “type-IV” damage due to creep voids and cracks in the fine-grained heat-affected zone (HAZ). There is no precedent for indicating the obvious creep strength degradation of welded joints under SFR temperatures (550 °C or less). Although obvious strength degradation of the welded joints has not yet been observed at 550 °C, it is fair to assume that the strength degradation will occur due to very long-term creep. Therefore, considering strength degradation due to “type-IV” damage is necessary. This paper proposes the creep-rupture curve and the welded joint strength-reduction factor (WJSRF). The creep-rupture curve of the welded joint was proposed by employing a second-order polynomial equation with LMP using region splitting analysis method, which is used for the base metal as well. The WJSRFs were proposed on the basis of design creep-rupture stress strength. The resulting allowable stress was conservative compared with that prescribed in ASME code and the Japan domestic regulation for thermal plants. In addition, the design of the hot-leg pipe in SFR was reviewed considering the WJSRFs.

A Review and Comparison of Floating Offshore Wind Turbine Model Experiments

Floating offshore wind turbines provide more access to deeper water than conventional fixed-bottom wind turbines, which expands the viable area for wind energy development, reduces visibility from shore, and can potentially be located in areas with a higher and steadier wind characteristic. However, since floating turbines are in the early prototype stage of development, there are very limited data to use for validating computer models of these machines. This lack of validation increases uncertainty and risk for future installations. In lieu of large scale test turbines, which are expensive to build and operate, a few institutions have conducted small scale experiments in wave basins. This paper will present a review of the past and planned model-scale floating offshore wind turbine experiments, with a focus on types of data collected and challenges encountered by these tests.The objective of this review is to provide a background for the Integrated Research Program on Wind Energy (IRPWind), specifically for Work Packages 6.1 and 6.2. The goal of these work packages is to create a database of both fixed-bottom and floating offshore wind turbine test cases that can be accessed by researchers to verify and validate computer-aided engineering codes. The database will consist of a number of benchmarks that will validate different parts of a given design code. This review will discuss two model experiments that are likely to be included in the IRPWind database.

Development of an engineering code for the implementation of aerodynamic control devices in BEM

Aeroelastic codes based on Blade Element Momentum theory are the standard used by many wind turbine designers. These codes usually include models and corrections for unsteady aerodynamics, tip and root effect, tower shadow and other effects. In general, this kind of codes does not include models to correctly simulate aerodynamic control devices. This paper presents some modifications including the unsteady contributions due to the flap motion (based on indicial models) and the spanwise (3D) effects (based on circulation theory), in order to simulate flaps in the blades. This method can be included in BEM codes in general and it could also be applied to another kind of control devices. The validation and verification show the accuracy of this method using experimental data for two-dimensional unsteady cases, and CFD for three-dimensional steady and unsteady cases.

Monte-Carlo code calculation of 3D reactor core model with usage of burnt fuel isotopic compositions, obtained by engineering codes

Abstract A burn-up calculation of large systems by Monte-Carlo code (MCU) is complex process and it requires large computational costs. Previously prepared isotopic compositions are proposed to be used for the Monte-Carlo code calculations of different system states with burnt fuel. Isotopic compositions are calculated by an approximation method. The approximation method is based on usage of a spectral functionality and reference isotopic compositions, that are calculated by the engineering codes (TVS-M, BIPR-7A and PERMAK-A). The multiplication factors and power distributions of FAs from a 3-D reactor core are calculated in this work by the Monte-Carlo code MCU using earlier prepared isotopic compositions. The separate conditions of the burnt core are observed. The results of MCU calculations were compared with those that were obtained by engineering codes.

Finite element analysis of steel structures – a review of useful guidelines

Purpose– Since the use of advanced finite element analysis (FEA) in the design of steel structures has been increasing its popularity in order to avoid unsafe or highly conservative designs, a solid know-how in computer-aided design (CAD) and engineering (CAE) codes is necessary. Therefore the purpose of this paper is to provide an extensive review of useful guidelines concerning modelling, simulation and result validation for the accurate performance of those analyses.Design/methodology/approach– Such guidelines are obtained from international steel design codes like Eurocode 3 and DNV, publications from experienced CAE engineers and renowned FE software companies like Ansys and Altair. Topics like mesh independence, the effect of the load sequence on the load bearing capacity and steel fracture criteria are underlined.Findings– Since the use of advanced FEA in the design of steel structures is becoming more and more traditional due to the increase of its competitiveness when compared to the use of (very) conservative design rules, a solid know-how in CAD and CAE codes is necessary.Practical implications– This work will be quite useful for structural steel stress engineers, contributing for a safer use of FEA in research and design.Originality/value– This work will be quite useful for structural steel stress engineers, contributing for a safer use of FEA in research and design.

Fatigue crack growth characteristics of austenitic stainless steel for cold‐stretched pressure vessels at cryogenic temperatures

Cold‐stretched pressure vessels made from austenitic stainless steel are widely used for storage and transportation of liquefied gases. Compared with conventional pressure vessels, cold‐stretched vessels have lots of advantages such as having thin walls, light weight, and low energy consumption. However, pressure vessels can be subjected to alternating loads at cryogenic temperatures, so it is important to investigate the fatigue characteristics of austenitic stainless steel for cold‐stretched vessels. This study presents the static and fatigue behavior of austenitic stainless steel 304 sampled from cold‐stretched pressure vessels in accordance with the American Society of Mechanical Engineers code. To compare the mechanical properties and fatigue behavior of austenitic stainless steel 304 in as‐received and cold‐stretched conditions (9 % strain level), tensile and fatigue crack growth tests were performed at room and cryogenic temperatures respectively. Fractography of the fractured specimens was carried out using a scanning electron microscope.

Modeling and Multi-Objective Optimization of Engine Performance and Hydrocarbon Emissions via the Use of a Computer Aided Engineering Code and the NSGA-II Genetic Algorithm

It is feared that the increasing population of vehicles in the world and the depletion of fossil-based fuel reserves could render transportation and other activities that rely on fossil fuels unsustainable in the long term. Concerns over environmental pollution issues, the high cost of fossil-based fuels and the increasing demand for fossil fuels has led to the search for environmentally friendly, cheaper and efficient fuels. In the search for these alternatives, liquefied petroleum gas (LPG) has been identified as one of the viable alternatives that could be used in place of gasoline in spark-ignition engines. The objective of the study was to present the modeling and multi-objective optimization of brake mean effective pressure and hydrocarbon emissions for a spark-ignition engine retrofitted to run on LPG. The use of a one-dimensional (1D) GT-Power™ model, together with Group Method of Data Handling (GMDH) neural networks, has been presented. The multi-objective optimization was implemented in MATLAB® using the non-dominated sorting genetic algorithm (NSGA-II). The modeling process generally achieved low mean squared errors (0.0000032 in the case of the hydrocarbon emissions model) for the models developed and was attributed to the collection of a larger training sample data using the 1D engine model. The multi-objective optimization and subsequent decisions for optimal performance have also been presented.