Review and Development of Primary Load Elevated Temperature Design Rules

2014 ◽  
Author(s):  
David J. Dewees ◽  
Benjamin F. Hantz
Keyword(s):  
High Temperature ◽  
Strain Analysis ◽  
Creep Model ◽  
Stress Strain ◽  
Creep Analysis ◽  
Elevated Temperature Design ◽  
High Temperature Steam ◽  
Multiaxial Creep ◽  
Selection Of

A recent high temperature steam header case study is extended here to include alternate methods of review, including elastic stress and isochronous strain analysis and accompanying limits. The previous creep analysis was formulated to be exactly consistent with the allowable stress basis, such that alternate design analysis methods and criteria could be rigorously compared. In the current work, the selection of the appropriate limits for elastic results is investigated, as discussed in previous literature, which is motivated by stress redistribution characteristics of the primary (and secondary) loading in a typical header. Next, use of isochronous stress-strain curves generated from the same consistent (Omega) creep model are used for analysis and compared to candidate strain limits. The analyses show that both elastic and isochronous analysis have potential for effective creep design in the context of current high temperature design modernization activities. Finally, multiaxial creep behavior and its effect on detailed creep, elastic and isochronous stress-strain analyses and corresponding limits is also introduced.

Grade 11 High Temperature Steam Header Case History and Benchmark

2016 ◽  
Author(s):  
Dave Dewees
Keyword(s):  
High Temperature ◽  
Elevated Temperature ◽  
Method Validation ◽  
Case History ◽  
Design Method ◽  
Fatigue Behavior ◽  
Method Performance ◽  
Elevated Temperature Design ◽  
High Temperature Steam ◽  
Grade 11

The cost and complexity of design method validation at the component level makes actual and comprehensive benchmark cases challenging to obtain. This is especially true of elevated temperature design methods where component and material response is complicated by time-dependent creep and possibly creep-fatigue behavior. To support current Design-by-Analysis modernization development within Section I of the ASME Boiler & Pressure Vessel Code, service examples that are comprehensive enough to allow method validation, while still being tractable in complexity have been identified. To this end, the case history of a Grade 11 high temperature steam outlet header that was retired after 23 of years of service is presented. Detailed damage and deformation information is available which allows validation of creep material models, as well as future evaluation of candidate elevated temperature design method performance.

Comparison of the Isochronous Method and a Time-Explicit Model for Creep Analysis

2008 ◽  
Author(s):  
William Koves ◽  
Mingxin Zhao
Keyword(s):  
Elevated Temperature ◽  
Large Scale ◽  
Time Dependent ◽  
Creep Model ◽  
Full Time ◽  
Pure Bending ◽  
Stress Strain ◽  
Creep Analysis ◽  
Generalized Time ◽  
Strain Method

The design of components or structures at elevated temperature is complex. The use of rigorous time dependent material models may not be practical for many large scale industrial problems. The use of simplified methods permits the creep analysis of components that would be impractical by rigorous time dependent models. The Isochronous Stress-Strain method is an approach that has been used extensively for the creep evaluation of elevated temperature components. The method has been used for the analysis of problems containing both primary and secondary stresses. The method has also been used to evaluate creep buckling problems. Although the method has been accepted as an alternative to a full time dependent creep analysis, the limitations and accuracy of the method have not been investigated systematically and are not fully understood. This study compares the isochronous stress-strain method with a generalized time-explicit creep model for materials in high temperature applications. Analytical solutions are developed for three basic loading configurations, including uniaxial tension, pure bending, and torsion in either load or displacement controlled conditions. Deformations, stresses, and creep strains are compared between the two different methods.

On Simplified Inelastic Method Using Material's Isochronous Stress–Strain Data for Creep Analysis

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
William Koves ◽  
Mingxin Zhao
Keyword(s):  
Elevated Temperature ◽  
Large Scale ◽  
Complex Loading ◽  
Pressure Vessels ◽  
Time Dependent ◽  
Creep Model ◽  
Stress Strain ◽  
Creep Analysis ◽  
Simplified Method ◽  
Strain Method

Design of components or structures at elevated temperature is complex and the use of rigorous time dependent material models may not be practical for many large scale industrial problems. The use of simplified methods permits creep analysis of components that would be impractical by rigorous time dependent models. The isochronous stress–strain method is an approach that has been used extensively for the creep evaluation of elevated temperature components. In practice, the method has been used for the analysis of problems containing both primary and secondary stresses, such as, for pressure vessels with structural discontinuities or creep buckling problems. Although the simplified method has been widely accepted as an alternative to creep analysis, its limitations and accuracy of the method have not been investigated systematically and are not fully understood under complex loading conditions. This study examines the isochronous stress–strain method against a generalized time-explicit creep model. Analytical solutions are developed for three basic loading configurations, including uniaxial tension, pure bending, and torsion, in either load or displacement controlled conditions. Fundamental behaviors of the simplified method are examined and discussed.

Delamination in the scoring and folding of paperboard

TAPPI Journal ◽  
2012 ◽  
Vol 11 (1) ◽  
pp. 61-66 ◽  
Author(s):  
DOEUNG D. CHOI ◽  
SERGIY A. LAVRYKOV ◽  
BANDARU V. RAMARAO
Keyword(s):  
Finite Element ◽  
Plane Deformation ◽  
Strain Analysis ◽  
Local Strain ◽  
Uniaxial Stress ◽  
Material Model ◽  
Element Model ◽  
Plastic Behavior ◽  
Stress Strain ◽  
Strain Fields

Delamination between layers occurs during the creasing and subsequent folding of paperboard. Delamination is necessary to provide some stiffness properties, but excessive or uncontrolled delamination can weaken the fold, and therefore needs to be controlled. An understanding of the mechanics of delamination is predicated upon the availability of reliable and properly calibrated simulation tools to predict experimental observations. This paper describes a finite element simulation of paper mechanics applied to the scoring and folding of multi-ply carton board. Our goal was to provide an understanding of the mechanics of these operations and the proper models of elastic and plastic behavior of the material that enable us to simulate the deformation and delamination behavior. Our material model accounted for plasticity and sheet anisotropy in the in-plane and z-direction (ZD) dimensions. We used different ZD stress-strain curves during loading and unloading. Material parameters for in-plane deformation were obtained by fitting uniaxial stress-strain data to Ramberg-Osgood plasticity models and the ZD deformation was modeled using a modified power law. Two-dimensional strain fields resulting from loading board typical of a scoring operation were calculated. The strain field was symmetric in the initial stages, but increasing deformation led to asymmetry and heterogeneity. These regions were precursors to delamination and failure. Delamination of the layers occurred in regions of significant shear strain and resulted primarily from the development of large plastic strains. The model predictions were confirmed by experimental observation of the local strain fields using visual microscopy and linear image strain analysis. The finite element model predicted sheet delamination matching the patterns and effects that were observed in experiments.

Topik-Topik Komunikasi Dakwah Dalam Mesej Akidah Kepada Masyarakat Orang Asli di Selangor

Sains Insani ◽  
2018 ◽  
Vol 3 (2) ◽  
pp. 15-21
Author(s):  
Zulkefli Aini ◽  
Abdul Ghafar Don ◽  
Ahmad Irdha Mokhtar ◽  
Nur Uswah Ahmad Fauzi
Keyword(s):  
Qualitative Study ◽  
Study Design ◽  
Verbal Feedback ◽  
Structured Interviews ◽  
Orang Asli ◽  
Case Study Design ◽  
Beliefs And Practice ◽  
Islamic Faith ◽  
Selection Of

One of the factors that can affect a person's behavior is a communication message. In the context of the da`wah, preachers who involved actively in da`wah communication with the Orang Asli should be able to ensure that the message conveyed can be understood by the target group. In addition, the selection of the correct messages of da`wah based on the foremost priority simplify the process of sharing information between the preachers and the Orang Asli. Accordingly, this article aims to identify specific topics of Islamic faith (akidah) submitted by the Orang Asli in the process of da`wah communication and to identify verbal feedback given by the preachers to the Orang Asli of the topics. This qualitative study using case study design and data was collected through semi-structured interviews. Interviews involving nine preachers were active in da`wah activity to the Orang Asli community in Selangor. Data were analyzed thematically according to the specified objectives. The study found that the topics frequently raised by the Orang Asli is concerned about belief in Allah, belief in Malaikat, and belief in Qada' and Qadar. The topics may be found within the framework of worldview in their beliefs and practice of ancient traditions. Therefore, the preachers gave verbal feedback on these topics is based on a clear and precise sample corresponding to the level of their thinking. The emphasis on these topics is very important to strengthen and purify the faith of the community.Keywords: Communication; Message; Preacher; Indigenous community Abstrak: Elemen mesej dalam komunikasi merupakan salah satu faktor yang dapat memberi kesan terhadap perubahan tingkah laku seseorang. Dalam konteks dakwah, pendakwah yang terlibat dalam proses komunikasi dakwah dengan Orang Asli seharusnya berkebolehan memastikan kandungan mesej yang disampaikan boleh difahami oleh sasaran dakwahnya. Di samping itu, pemilihan mesej dakwah yang betul mengikut keutamaan memudahkan proses perkongsian maklumat antara pendakwah dengan Orang Asli. Sehubungan dengan itu, artikel ini bertujuan untuk mengenalpasti topik-topik tertentu dalam mesej akidah yang dikemukakan oleh masyarakat Orang Asli kepada pendakwah dan mengenalpasti maklum balas lisan yang diberikan oleh pendakwah kepada Orang Asli terhadap topik tersebut. Kajian kualitatif ini menggunakan reka bentuk kajian kes dengan pengumpulan data melalui temu bual separa struktur. Temu bual melibatkan sembilan orang pendakwah yang aktif dalam aktiviti dakwah masyarakat Orang Asli di Selangor. Data kajian dianalisis secara tematik mengikut objektif yang ditentukan. Kajian ini mendapati bahawa topik-topik yang sering dikemukan oleh Orang Asli kepada pendakwah dalam penyampaian mesej akidah ialah berkenaan tentang keimanan kepada Allah SWT, keimanan kepada malaikat, dan keimanan kepada qada’ dan qadar. Topik-topik berkenaan didapati berada dalam kerangka worldview kepercayaan dan amalan tradisi mereka. Sehubungan dengan itu, pendakwah memberikan maklum balas lisan terhadap topik-topik tersebut adalah berdasarkan keterangan yang jelas dan contoh yang tepat bersesuaian dengan tahap pemikiran mereka. Penekanan terhadap topik-topik tersebut merupakan perkara yang penting dalam rangka mengukuhkan dan memurnikan akidah masyarakat Orang Asli.Kata kunci: Komunikasi; Mesej; Pendakwah; Komuniti Orang Asli

Stress-Strain Analysis and Simulation for Estimation of Cutting Forces on the Skin

2015 ◽  
Vol 9 (6) ◽  
pp. 583
Author(s):  
Dario German Buitrago ◽  
Luis Carlos Ruíz ◽  
Olga Lucia Ramos
Keyword(s):  
Cutting Forces ◽  
Strain Analysis ◽  
Stress Strain

Passive Auto-Focus Algorithm for Correcting Image Distortions Caused by Gas Flow in High-Temperature Measurements of Surface Phenomena

2012 ◽  
Vol 17 (4) ◽  
pp. 379-384 ◽  
Author(s):  
Krzysztof Strzecha ◽  
Tomasz Koszmider ◽  
Damian Zarębski ◽  
Wojciech Łobodziński
Keyword(s):  
High Temperature ◽  
Gas Flow ◽  
Temperature Measurements ◽  
Surface Phenomena ◽  
Auto Focus ◽  
High Temperature Measurements

Abstract In this paper, a case-study of the auto-focus algorithm for correcting image distortions caused by gas flow in high-temperature measurements of surface phenomena is presented. This article shows results of proposed algorithm and methods for increasing its accuracy.

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