Optimal Structural Design Under Creep Conditions

1996 ◽  
Vol 49 (9) ◽  
pp. 433-446 ◽  
Author(s):  
Michał Z˙yczkowski
Keyword(s):  
Structural Design ◽  
Elevated Temperatures ◽  
Review Article ◽  
Future Research ◽  
Metal Structures ◽  
Optimal Structural Design ◽  
University Of Technology ◽  
Creep Stiffness ◽  
Plates And Shells ◽  
Elastic Design

Optimal design of structures, or rather just of simple structural elements working under creep conditions, belongs to the most recent branches of structural optimization. It was initiated by four papers published in the years 1967-1968 (Reitman, Prager, Nemirovsky, and Z˙yczkowski). The most important differences with respect to elastic design are as follows: factor of time appearing in the constraints, a great variety of constitutive equations of creep or viscoplasticity, creep rupture hypotheses, creep buckling theories, various definitions of creep stiffness, etc. Moreover, the constraints related to stress-relaxation are quite new. So, it is almost impossible to establish a sufficiently general theory, and various types of problems must be treated separately by appropriate methods. On the other hand, the problems of optimization under creep conditions are important in view of metal structures working at elevated temperatures, structures made of plastics, concrete, etc. This review article gives a classification of problems and then a review of results obtained for bars, columns, arches, trusses, frames, plates, and shells. Over thirty percent of these results were obtained at the Cracow University of Technology. This is an extended and updated version of an earlier review article published in AMR41(12), December, 1988, discusses specific features of the branch of optimal structural design under consideration, as well as perspectives for future research. This review article contains 187 references.

Optimal Structural Design Under Creep Conditions

1988 ◽  
Vol 41 (12) ◽  
pp. 453-461 ◽  
Author(s):  
Michał Z˙yczkowski
Keyword(s):  
Structural Design ◽  
Elevated Temperatures ◽  
Future Research ◽  
Structural Elements ◽  
Metal Structures ◽  
Optimal Structural Design ◽  
Creep Buckling ◽  
Creep Stiffness ◽  
Plates And Shells

Optimal design of structures, or rather just of simple structural elements working under creep conditions, belongs to the most recent branches of structural optimization: It was initiated by four papers published in the years 1967–1968 (Reitman, Prager, Nemirovsky, and Z˙yczkowski). The most important differences with respect to elastic or plastic design are as follows: factor of time appearing in the constraints, a great variety of constitutive equations of creep or viscoplasticity, of creep rupture hypotheses, creep buckling theories, various definitions of creep stiffness, etc. Moreover, the constraints related to stress–relaxation are quite new. So, it is almost impossible to establish a sufficiently general theory and various types of problems must be treated separately by appropriate methods. On the other hand, the problems of optimization under creep conditions are important in view of metal structures working at elevated temperatures, structures made of plastics, concrete, etc. The paper gives classification of problems and then a review of results obtained for bars, columns, arches, trusses, frames, plates, and shells. Over 30% of those results were obtained at the Technical University of Cracow. This paper discusses specific features of the branch of optimal structural design under consideration as well as perspectives of future research.

RECLAMATION AND CULVERT CROSSINGS MADE OF CORRUGATED PIPES ON SPAWNING STREAMS

2020 ◽  
pp. 68-77
Author(s):  
O.N. CHERNYKH ◽  
◽  
A.V. RBURLACHENKO
Keyword(s):  
Single Point ◽  
Experimental Studies ◽  
Fish Passage ◽  
Future Research ◽  
Fish Stocks ◽  
Metal Structures ◽  
Natural Reproduction ◽  
Spiral Shape ◽  
Corrugated Metal ◽  
Spawning Streams

Recommendations are presented for solving issues that arise in the design and operation of tubular transport crossings of corrugated metal structures through spawning streams while ensuring the safety and natural reproduction of fish stocks. There are discussed the results of experimental studies of culverts made of metal corrugated pipes with a normal and spiral shape of corrugation the bottom of which is buried and filled with suitable granular material to the level of the natural channel of a small watercourse. It is established that when 10% of the area of the corrugated pipe is occupied by stone filling, its throughput is reduced by about 10-12%. Based on the review of the existing literature and the results of laboratory experiments, data is provided to estimate the values of the roughness coefficients of the composite cross-section of a single-point junction and directions for future research on culvert reclamation are outlined. Studying of the structure of the velocity distribution in culverts can lead to the improved conditions for fish passage without installing special structural elements in the transit path of the fish passage structure.

scholarly journals Mulching as water-saving technique in dryland agriculture: review article

2019 ◽  
Vol 43 (1) ◽  
Author(s):  
Mohammad Abdul Kader ◽  
Ashutus Singha ◽  
Mili Amena Begum ◽  
Arif Jewel ◽  
Ferdous Hossain Khan ◽  
...  
Keyword(s):  
Arid Regions ◽  
Review Article ◽  
Water Saving ◽  
Future Research ◽  
Agricultural Water ◽  
Plastic Mulch ◽  
Dryland Agriculture ◽  
Crop Cultivation ◽  
Agricultural Water Resources ◽  
Semi Arid

Abstract Agricultural water resources have been limited over the years due to global warming and irregular rainfall in the arid and semi-arid regions. To mitigate the water stress in agriculture, mulching has a crucial impact as a water-saving technique in rain-fed crop cultivation. It is important mainly for preserving soil moisture, relegating soil temperature, and limiting soil evaporation, which affects the crop yield. Mulching has many strategic effects on soil ecosystem, crop growth, and climate. Mulch insulates the soil, helping to provide a buffer from cold and hot temperatures that have a crucial activity in creating beautiful and protected landscapes. This study has accumulated a series of information about both organic and plastic mulch materials and its applicability on crop cultivation. Moreover, future research potentials of mulching with modeling were discussed to quantify water loss in agriculture.

scholarly journals Materials for Production of High and Ultra-High Performance Concrete: Review and Perspective of Possible Novel Materials

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4304
Author(s):  
Markssuel Teixeira Marvila ◽  
Afonso Rangel Garcez de de Azevedo ◽  
Paulo R. de de Matos ◽  
Sergio Neves Monteiro ◽  
Carlos Maurício Fontes Vieira
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Review Article ◽  
Cement Matrix ◽  
Bibliographic Databases ◽  
Future Research ◽  
Chemical Additives ◽  
Ultra High Performance Concrete ◽  
Conventional Concrete ◽  
Essential Components

This review article proposes the identification and basic concepts of materials that might be used for the production of high-performance concrete (HPC) and ultra-high-performance concrete (UHPC). Although other reviews have addressed this topic, the present work differs by presenting relevant aspects on possible materials applied in the production of HPC and UHPC. The main innovation of this review article is to identify the perspectives for new materials that can be considered in the production of novel special concretes. After consulting different bibliographic databases, some information related to ordinary Portland cement (OPC), mineral additions, aggregates, and chemical additives used for the production of HPC and UHPC were highlighted. Relevant information on the application of synthetic and natural fibers is also highlighted in association with a cement matrix of HPC and UHPC, forming composites with properties superior to conventional concrete used in civil construction. The article also presents some relevant characteristics for the application of HPC and UHPC produced with alkali-activated cement, an alternative binder to OPC produced through the reaction between two essential components: precursors and activators. Some information about the main types of precursors, subdivided into materials rich in aluminosilicates and rich in calcium, were also highlighted. Finally, suggestions for future work related to the application of HPC and UHPC are highlighted, guiding future research on this topic.

Noncontacting Vibration Measurement Using a Massless Interferometric Accelerometer

1995 ◽  
Author(s):  
Keyu Li
Keyword(s):  
Elevated Temperatures ◽  
Laser Light ◽  
Vibration Measurement ◽  
Object Surface ◽  
Out Of Plane ◽  
Plates And Shells ◽  
Fringe Patterns ◽  
Hostile Environments ◽  
Derivatives Of ◽  
Object Behavior

Abstract An interferometric strain measurement technique is extended to vibration measurements. The technique is based on two micro-indentations placed on an object surface using a combination of diffraction and interference of laser light. Relative displacements between the two indentations and derivatives of in-plane and out-of-plane vibrational displacements are measured by analyzing the phase shift of the interference fringe patterns. The technique can be used to study bending stress and deflection problems in vibrational beams, plates and shells. The displacement derivatives are measured in real time, from which time derivatives or the velocity and acceleration of the displacement derivative as well as vibrational frequency can be determined. The technique has advantages over an accelerometer in that it is noncontacting and does not require attachment of the transducer to the object which could alter the object behavior. In addition, it has many desirable features such as being extremely compact, massless, and applicable to hostile environments such as those associated with production and elevated temperatures.

On buckling and free vibration studies of sandwich plates and cylindrical shells: A review

2018 ◽  
Vol 33 (5) ◽  
pp. 673-724 ◽  
Author(s):  
Pavan Kumar ◽  
CV Srinivasa
Keyword(s):  
Free Vibration ◽  
Laminated Composite ◽  
Free Vibration Analysis ◽  
Functionally Graded ◽  
Future Research ◽  
Sandwich Plates ◽  
Composite Sandwich ◽  
Sandwich Plates And Shells ◽  
Graded Material ◽  
Plates And Shells

Many review articles were published on free vibration and buckling of laminated composites, sandwich plates, and shells. The present article reviews the literature on the buckling and free vibration analysis of shear deformable isotropic and laminated composite sandwich plates and shells using various methods available for plates in the past few decades. Various theories, finite element modeling, and experimentations have been reported for the analysis of sandwich plates and shells. Few papers on functionally graded material plates, plates with smart skin (electrorheological, magnetorheological, and piezoelectric), and also viscoelastic materials were also reviewed. The scope for future research on sandwich plates and shells was also accessed.

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