Numerical modeling of complex processes in the cyclic deformation of structural elements under nonisothermal loading

1987 ◽  
Vol 19 (2) ◽  
pp. 197-203
Author(s):  
S. F. Kashchenko ◽  
V. A. Petushkov ◽  
A. N. Romanov
Keyword(s):  
Numerical Modeling ◽  
Cyclic Deformation ◽  
Structural Elements ◽  
Nonisothermal Loading ◽  
Complex Processes

scholarly journals Statistical Estimation of Resistance to Cyclic Deformation of Structural Steels and Aluminum Alloy

Metals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 47
Author(s):  
Žilvinas Bazaras ◽  
Vaidas Lukoševičius
Keyword(s):  
Cyclic Deformation ◽  
Operational Reliability ◽  
Loading Conditions ◽  
Structural Elements ◽  
Research Papers ◽  
Processing Technologies ◽  
Cycle Loading ◽  
Distribution Limits ◽  
Probability Methods ◽  
Cycle Diagram

Resistance to cyclic loading is a key property of the material that determines the operational reliability of the structures. When selecting a material for structures operating under low-cycle loading conditions, it is essential to know the cyclic deformation characteristics of the material. Low-cycle strain diagrams are very sensitive to variations in chemical composition, thermal processing technologies, surface hardening, loading conditions, and other factors of the material. The application of probability methods enables the increase in the life characteristics of the structures and the confirmation of the cycle load values at the design phase. Most research papers dealing with statistical descriptions of low-cycle strain properties do not look into the distribution of low-cycle diagram characteristics. The purpose of our paper is to provide a probability assessment of the low-cycle properties of materials extensively used in the automotive and aviation industries, taking into account the statistical assessment of the cyclic elastoplastic strain diagrams or of the parameters of the diagrams. Materials with contrasting cyclic properties were investigated in the paper. The findings of the research allow for a review of durability and life of the structural elements of service facilities subjected to elastoplastic loading by assessing the distribution of low-cycle strain parameters, as well as the allowed distribution limits.

scholarly journals Numerical Modeling of Fillet and Butt Welds in Steel Structural Elements with Verification Using Experiment

2017 ◽  
Vol 190 ◽  
pp. 318-325 ◽  
Author(s):  
Martin Krejsa ◽  
Jiri Brozovsky ◽  
David Mikolasek ◽  
Premysl Parenica ◽  
Lenka Koubova ◽  
...  
Keyword(s):  
Numerical Modeling ◽  
Structural Elements ◽  
Butt Welds

scholarly journals Parametric analysis related to dimensioning of tubular steel columns filled with concrete in a fire situation

2022 ◽  
Vol 15 (2) ◽  
Author(s):  
Fábio Masini Rodrigues ◽  
Armando Lopes Moreno Júnior ◽  
Jorge Munaiar Neto
Keyword(s):  
Mechanical Properties ◽  
Numerical Modeling ◽  
Temperature Field ◽  
Moisture Content ◽  
Numerical Models ◽  
Physical And Mechanical Properties ◽  
Sensitivity Study ◽  
Steel Tube ◽  
Structural Elements ◽  
Steel Columns

ABSTRACT For the dimensioning of structural elements in fire situation, simplified equations and parameters are commonly used in analytical equations or numerical models. More complex equations or simplified values can be chosen by the designer for determine materials properties in high temperature in numerical models, however, numerical modeling can be quite sensitive to the variation of some of the physical and mechanical properties. In this paper, the sensitivity of the numerical model in relation to the values according to the level of simplification chosen was evaluated, presenting an analysis in relation to the results found to contribute to the choice of these parameters and presenting the indications found in the literature. In this sense, this work presents a study of sensitivity to the variation of the values of steel and concrete properties, presented in the Eurocode and Brazilian standards, in addition to the moisture content and emissivity of the surface exposed to fire, for the dimensioning, in a fire situation, of steel tube columns, of circular and square section, filled with concrete. The studies were carried out via numerical modeling developed in the software ABAQUS. It was verified that the resulting emissivity values equal to 0.7 or 0.8, recommended in the literature, are conservative, and the choice of either does not bring significant changes in the temperature field obtained for the structural elements under analysis. It was also verified that the concrete moisture content is a relevant aspect for the formation of its temperature field, also affecting, but to a lesser extent, the steel temperature. Regarding the physical and mechanical properties of the materials, this sensitivity study suggests the adoption of the values from the equations presented in Eurocodes, without simplifications, and with the specific heat and thermal conductivity of the concrete, adopted in accordance with the Eurocode 4.

scholarly journals Numerical modeling of crack initiation and propagation processes in various specimen’s types using the GTN material damage model

2021 ◽  
Vol 5 (1) ◽  
pp. 49-56
Author(s):  
Andrew Kravchuk ◽  
Eugene Kondriakov ◽  
Valery Kharchenko
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Numerical Modeling ◽  
Crack Initiation ◽  
Damage Model ◽  
Material Damage ◽  
Structural Elements ◽  
The Finite Element Method ◽  
Crack Initiation And Propagation ◽  
Initiation And Propagation

Problematic. A combination of experimental and computational methods for studying the processes of crack initiation and propagation in various specimen’s types is used to determine the mechanical properties of materials, as well as to improve the accuracy of assessing the strength and durability of structural elements. Research objective. Determination of the parameters of the Gurson-Tvergaard-Needleman (GTN) material damage model based on the numerical modeling results of various specimen’s types under various types of loading for steel 22K using the finite element method. Realization technique. Using the finite element method, numerical modeling of the processes of cracks nucleation and propagation in cylindrical specimens under uniaxial tension, in Charpy specimens under dynamic loading, and also in CT specimens under quasi-static loading was carried out for steel 22K using the GTN material damage model. The results of research. By comparing the experimental and numerical results, the full set of GTN material model parameters for steel 22K was determined. The stress state in the crack tip area and the kinetics of its propagation in the material of various specimen’s types under static and dynamic loading were estimated. Conclusions. The GTN material damage model with the parameter values determined from experiments, can be used for numerical simulation of the processes of crack initiation and propagation both in specimens of various types under various loading types, and in structural elements.

scholarly journals EXPERIMENTAL AND NUMERICAL MODELING OF TSUNAMI LOADING ON STRUCTURES

2011 ◽  
Vol 1 (32) ◽  
pp. 2 ◽  
Author(s):  
Ioan Nistor ◽  
Dan Palermo ◽  
Andrew Cornett ◽  
Taofiq Al-Faesly
Keyword(s):  
Numerical Modeling ◽  
Field Data ◽  
Structural Engineering ◽  
Coastal Areas ◽  
Structural Elements ◽  
Engineering Project ◽  
The Past ◽  
The Impact ◽  
Experimental And Numerical Modeling ◽  
Comprehensive Research Program

The results of a comprehensive research program on tsunami-induced forces on infrastructure located in coastal areas are presented. This research project is the result of an extensive interdisciplinary project (coastal and structural engineering) which spanned over the past five years and which included several field data reconnaissance missions, as well as analytical, experimental and numerical modeling of the extreme hydrodynamic forces on buildings and their component structural elements. The purpose of this research and engineering project is to elucidate the complex hydrodynamic mechanisms of the impact and extreme loadings on buildings and to properly quantify loads and further propose and derive new formulations for the design of structures located in the vicinity of the shoreline in tsunami-prone coastal areas.

scholarly journals Hydraulic regimes and hydrostatic pressure of the flow on the elements of fastenings of the downstream of water outlets

2021 ◽  
Vol 264 ◽  
pp. 03053
Author(s):  
Sanatjon Khidirov ◽  
Zokhidjon Ishankulov ◽  
Jakhongir Kosimov ◽  
Durdona Tadjieva ◽  
Panji Nurmatov ◽  
...  
Keyword(s):  
Hydrostatic Pressure ◽  
Kinetic Energy ◽  
Water Intake ◽  
Water Injection ◽  
Hydraulic Structures ◽  
Structural Elements ◽  
Complex Processes ◽  
Hydropower Plants ◽  
Selection Of ◽  
Comprehensive Study

A comprehensive study of the flow of water plays an important role in the design of the area of the lower reaches of the drainage and drainage structures of hydraulic structures. In particular, the complex processes associated with the flow movement in the lower reaches of low and medium pressure reservoirs play an important role in the selection of the appearance of the structure, structural elements and their shapes, sizes and location conditions. One of the important issues is to assess the strength of the elements of the lower basins of water intake facilities and hydropower plants in the current reservoirs, to determine the mode of connection of the basins, to improve the methods of quenching kinetic energy in the reinforced areas of the lower basin. Based on the 2 schemes adopted in this article, the hydrostatic pressures of several types of power extinguishers installed in the area of the water injection well, providing the bottom pound strength, were determined for the experimental device.

Structural phenomena in the growth of carbon nanotubes

1993 ◽  
Vol 51 ◽  
pp. 750-751
Author(s):  
Jun Jiao
Keyword(s):  
Carbon Nanotubes ◽  
Growth Mechanism ◽  
Carbonaceous Material ◽  
Cluster Growth ◽  
Structural Elements ◽  
Rich Variety ◽  
Different Shapes ◽  
Point To Point

HREM studies of the carbonaceous material deposited on the cathode of a Huffman-Krätschmer arc reactor have shown a rich variety of multiple-walled nano-clusters of different shapes and forms. The preparation of the samples, as well as the variety of cluster shapes, including triangular, rhombohedral and pentagonal projections, are described elsewhere.The close registry imposed on the nanotubes, focuses attention on the cluster growth mechanism. The strict parallelism in the graphitic separation of the tube walls is maintained through changes of form and size, often leading to 180° turns, and accommodating neighboring clusters and defects. Iijima et. al. have proposed a growth scheme in terms of pentagonal and heptagonal defects and their combinations in a hexagonal graphitic matrix, the first bending the surface inward, and the second outward. We report here HREM observations that support Iijima’s suggestions, and add some new features that refine the interpretation of the growth mechanism. The structural elements of our observations are briefly summarized in the following four micrographs, taken in a Hitachi H-8100 TEM operating at an accelerating voltage of 200 kV and with a point-to-point resolution of 0.20 nm.

Designing TIMP (tissue inhibitor of metalloproteinases) variants that are selective metalloproteinase inhibitors

2003 ◽  
Vol 70 ◽  
pp. 201-212 ◽  
Author(s):  
Hideaki Nagase ◽  
Keith Brew
Keyword(s):  
Three Dimensional ◽  
Therapeutic Interventions ◽  
Tissue Inhibitors Of Metalloproteinases ◽  
Structural Basis ◽  
Structural Elements ◽  
Ridge Structure ◽  
Extracellular Matrix Components ◽  
Metalloproteinase Inhibitors ◽  
The Matrix ◽  
A Disintegrin And Metalloproteinase

The tissue inhibitors of metalloproteinases (TIMPs) are endogenous inhibitors of the matrix metalloproteinases (MMPs), enzymes that play central roles in the degradation of extracellular matrix components. The balance between MMPs and TIMPs is important in the maintenance of tissues, and its disruption affects tissue homoeostasis. Four related TIMPs (TIMP-1 to TIMP-4) can each form a complex with MMPs in a 1:1 stoichiometry with high affinity, but their inhibitory activities towards different MMPs are not particularly selective. The three-dimensional structures of TIMP-MMP complexes reveal that TIMPs have an extended ridge structure that slots into the active site of MMPs. Mutation of three separate residues in the ridge, at positions 2, 4 and 68 in the amino acid sequence of the N-terminal inhibitory domain of TIMP-1 (N-TIMP-1), separately and in combination has produced N-TIMP-1 variants with higher binding affinity and specificity for individual MMPs. TIMP-3 is unique in that it inhibits not only MMPs, but also several ADAM (a disintegrin and metalloproteinase) and ADAMTS (ADAM with thrombospondin motifs) metalloproteinases. Inhibition of the latter groups of metalloproteinases, as exemplified with ADAMTS-4 (aggrecanase 1), requires additional structural elements in TIMP-3 that have not yet been identified. Knowledge of the structural basis of the inhibitory action of TIMPs will facilitate the design of selective TIMP variants for investigating the biological roles of specific MMPs and for developing therapeutic interventions for MMP-associated diseases.

Sign in / Sign up

Export Citation Format

Share Document