The Development of High Temperature Design Methods Based on Reference Stresses and Bounding Theorems

1979 ◽  
Vol 101 (4) ◽  
pp. 349-355 ◽  
Author(s):  
I. W. Goodall ◽  
F. A. Leckie ◽  
A. R. S. Ponter ◽  
C. H. A. Townley
Keyword(s):  
High Temperature ◽  
Creep Deformation ◽  
Design Methods ◽  
Minimum Requirement ◽  
Elastic Plastic ◽  
Design Engineers ◽  
Reference Stress ◽  
Recent Developments ◽  
Shakedown Limit

The paper summarizes some recent developments in the analysis of structures by use of bounding theorems and reference stress techniques. In many instances these techniques may be used by design engineers in simplifying the analysis of structures operating in the creep range. This is particularly true of components operating below a modified shakedown limit as the design methods need be no more complex than those currently used below the creep range. Above the modified shakedown limit bounding theorems may be used to determine deformations but require a cyclic elastic-plastic solution as a minimum requirement. The bounds however do allow a simplified treatment of the creep deformation to be made.

Rewiew of Fracture and Fatigue in Ceramic Matrix Composites

2000 ◽  
Vol 53 (6) ◽  
pp. 147-174 ◽  
Author(s):  
Victor Birman ◽  
Larry W. Byrd
Keyword(s):  
High Temperature ◽  
State Of The Art ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Review Article ◽  
Successful Implementation ◽  
Matrix Composites ◽  
Recent Developments ◽  
Hostile Environments

A review of recent developments and state-of-the-art in research and understanding of damage and fatigue of ceramic matrix composites is presented. Both laminated as well as woven configurations are considered. The work on the effects of high temperature on fracture and fatigue of ceramic matrix composites is emphasized, because these materials are usually designed to operate in hostile environments. Based on a detailed discussion of the mechanisms of failure, the problems that have to be addressed for a successful implementation of ceramic matrix composites in design and practical operational structures are outlined. This review article includes 317 references.

A Review on High Temperature Stable Anatase TiO2 Photocatalysts

2016 ◽  
Vol 855 ◽  
pp. 78-93 ◽  
Author(s):  
Pradeepan Periyat ◽  
Binu Naufal ◽  
Sanjay Gopal Ullattil
Keyword(s):  
High Temperature ◽  
Metal Ions ◽  
Photocatalytic Performance ◽  
Anatase Phase ◽  
Co Doping ◽  
Phase Stabilization ◽  
Antibacterial Coatings ◽  
Recent Developments ◽  
Self Cleaning

This review focuses on the recent developments of high temperature stable anatase TiO2 photocatalyst. Eventhough TiO2 exists in different forms anatase, rutile and brookite, anatase phase stabilization is often the key to obtain the highest photocatalytic performance for TiO2, particularly for the use as an antibacterial and self-cleaning coatings in high temperature processed ceramics. Different methods available for the anatase stabilization in literature are critically reviewed and emphasis is placed on relatively recent developments. Currently available methods of anatase stabilizations are classified in to four categories viz (i) doping with metal ions (ii) doping with non-metal ions (iii) co-doping with metal and non-metal ions and (iv) dopant free stabilization by oxygen richness. Further to this, the application of these high temperature stabilized anatase TiO2 photocatalyst on various ceramics substrates such as tile, glass and sanitary wares as self-cleaning and antibacterial coatings are also been briefly discussed.

Use of High-Temperature Superconductors in High Speed Electronic Switches with Current Gain

1987 ◽  
Vol 99 ◽  
Author(s):  
Bryan A. Biegel ◽  
R. Singh
Keyword(s):  
High Temperature ◽  
Josephson Junction ◽  
Resonant Tunneling ◽  
High Speed ◽  
High Temperature Superconductors ◽  
Semiconductor Devices ◽  
Proximity Effects ◽  
Current Gain ◽  
Recent Developments ◽  
Electronic Switches

ABSTRACTRecent developments in superconductivity have taken 77 K superconducting electronics from a dream to a likelihood. Rather than following the conventional path by developing Josephson junction-based devices, this paper discusses the unique possibilities of hybrid superconductor/semiconductor devices. The two devices discussed are a true three-terminal hybrid resonant tunneling transistor and the semiconductor-coupled Josephson junction. Also, a list is given of as yet uninvestigated issues concerning the new superconductors and their proximity effects with semiconductors -issues that are critical to the operation of these hybrid superconductor/semiconductor devices.

Developments in Cyclic Analysis and High Temperature Design

2005 ◽  
Author(s):  
Peter Carter ◽  
Douglas L. Marriott
Keyword(s):  
High Temperature ◽  
Power Systems ◽  
Creep Damage ◽  
Limit Load ◽  
Cyclic Stress ◽  
Research Literature ◽  
Stress Classification ◽  
Analysis Technique ◽  
Recent Developments

Design for cyclic loading is emerging as a key question for next generation power systems. Recent developments in techniques for cyclic stress analysis have significant implications for high temperature design. In the same way that limit load analysis is now being used to overcome the difficulties and guesswork of stress classification for steady primary loads, so shakedown and ratcheting analysis can eliminate the more difficult problems of stress classification for cyclic loads. The paper shows how reference stresses defined for shakedown and ratcheting provide rapid and conservative information for design against rupture and creep damage, deformation and strain accumulation, and ratcheting. These techniques will provide additional insights to designers and are likely to augment rather than replace, existing options. These ideas have existed in the research literature for some time, but have now become more accessible by the general industry with a new analysis technique in a commercial finite element code. Examples are given which demonstrate the methodology for nozzles having non-thermal secondary stresses, and prediction of long-term distortion in thermal shock problems.

Partitioned Cyclic Fatigue Damage Evolution Model for PB-Free Solder Materials

2007 ◽  
Author(s):  
Leila J. Ladani ◽  
A. Dasgupta
Keyword(s):  
Fatigue Damage ◽  
Creep Deformation ◽  
Damage Evolution ◽  
Evolution Model ◽  
Micro Scale ◽  
Elastic Plastic ◽  
Constitutive Properties ◽  
Free Solder ◽  
Cyclic Damage ◽  
Creep Deformations

This study presents an approach to predict the degree of material degradation and the resulting changes in constitutive properties during cyclic loading in viscoplastic materials in micro-scale applications. The objective in the modeling approach is to address the initiation and growth of distributed micro-damage, in the form of micro-cracks and micro-voids, as a result of cyclic, plastic and creep deformations of material. This study extends an existing micromechanics-based approach, developed for unified viscoplastic models [Wen, et al, 2001], which uses dislocation mechanics to predict damage due to distributed micro-scale fatigue crack initiation [Mura and Nakasone, 1990]. In the present study, the approach is extended to a partitioned viscoplastic framework, because the micro-scale mechanisms of deformation and damage are different for plastic and creep deformation. In this approach, the model constants for estimating cyclic damage evolution are allowed to be different for creep and plastic deformations. A partitioned viscoplastic constitutive model is coupled with an energy partitioning (E-P) damage model [Oyan and Dasgupta, 1992] to assess fatigue damage evolution due to cyclic elastic, plastic and creep deformations. Wen’s damage evolution model is extended to include damage evolution due to both plastic and creep deformations. The resulting progressive degradation of elastic, plastic and creep constitutive properties are continuously assessed and updated. The approach is implemented on a viscoplastic Pb-free solder. Dominant deformation modes in this material are dislocation slip for plasticity and diffusion-assisted dislocation climb/glide for creep. The material’s behavior shows a good correlation with the proposed damage evolution model. Damage evolution constants for plastic and creep deformation were obtained for this Pb-free solder from load drop data collected from the mechanical cycling experiments at different temperatures. The amount of cyclic damage is evaluated and compared with experiment.

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