scholarly journals Durability of metal structures under quasi-static load

2018 ◽  
Vol 224 ◽  
pp. 02091 ◽  
Author(s):  
Dmitriy Ogorelkov ◽  
Vladimir Mironov ◽  
Olga Lukashuk
Keyword(s):  
Static Load ◽  
Plastic Material ◽  
Material Strength ◽  
Metal Structures ◽  
Fatigue Process ◽  
Calculation Methodology ◽  
Cyclic Degradation ◽  
Original Part ◽  
Brittle State ◽  
Local Transition

Failure of materials and structures is one of unresolved problems of mechanics. This paper offers an approximate approach to assessing durability of products on the basis of a mechanical experiment. The experiment represents the fatigue process as a transition of a plastic material into its brittle state. A simplified physical model – which could be used to build a mathematical model of fatigue process – hangs on a local transition of a plastic material into its brittle state. The calculation methodology includes both an original part on cyclic degradation of material strength and correlations based on experiments and checked by design routines. Two approaches to calculating the durability of a randomly-loaded object are compared: using the equation of cyclic degradation of strength and the rule of linear summation of fatigue damages. The results obtained are useful for improving methodologies of calculating service life or durability of structures.

Disk and Strip Forging with Side-surface Foldover—Part 1: Velocity Field and Upper-Bound Analysis

1978 ◽  
Vol 100 (4) ◽  
pp. 421-427 ◽  
Author(s):  
B. Avitzur ◽  
R. A. Kohser
Keyword(s):  
Velocity Field ◽  
Upper Bound ◽  
Plastic Material ◽  
Relative Size ◽  
Side Surface ◽  
Friction Material ◽  
Material Strength ◽  
Upper Bound Analysis ◽  
Zone Ii ◽  
Bound Analysis

With the assumptions of a Mises’ rigid, perfectly-plastic material and constant shear stress friction prevailing between the forge platens and deforming solid, the upper-bound analysis technique was applied to the upset forging of rectangular strip and solid cylindrical disks in an effort to incorporate the combined phenomena of bluge and fold. A two-zone velocity field was proposed for each geometry with Zone I occupying the interior volume and Zone II, the region near the free-surface periphery. The velocity field in Zone I was chosen as the exponential cusp-type used successfully in several previous analyses. Zone II was represented by a velocity field compatible with a foldover phenomenon and kinematically admissible with respect to boundary conditions and compatibility with Zone I. Solutions based on the above assumptions provide the forging pressure as a function of specimen geometry, interface friction, material strength, rate of bulge formation and relative size of Zone II. Minimization with respect to the last two variables provides the optimum rate of barreling or bulging and determines the degree of foldover expected.

The Ability to Determine the Degree of Damage to Welds Depending on Damage to the Welding Elements

2019 ◽  
Vol 968 ◽  
pp. 240-247
Author(s):  
Ihor Tvardovskyi ◽  
Tetiana Kalinina ◽  
Olexandr Chuchmai
Keyword(s):  
Aggressive Medium ◽  
Experimental Studies ◽  
Operational Reliability ◽  
Technical Condition ◽  
Material Strength ◽  
Prolonged Action ◽  
Metal Structures ◽  
Metal Elements ◽  
Long Time ◽  
External Loads

In real conditions, bearing elements of metal structures are often subjected to the effect, both external loads, and various aggressive medium, under the influence of which corrosion processes are developed. Corrosive processes with prolonged action lead to a decrease the working area of ​​the welds and accordingly connected elements. During the examination of the technical condition of existing metal structures operating in aggressive medium, it is often necessary to perform calculations to define the reserve of strength. In case of exhaustion of material strength it is necessary to develop measures to strengthen certain weakened elements. Herewith, the quantitative assessment of the reduction of the reliability of welds remains a matter that requires additional research. To study the change in the ratio of squares of metal elements under the influence of the prolonged action of various aggressive medium, specially directed experimental studies were carried out. The results of studies allowed to determine the reserves of the strength of the welded elements in relation to the welds themselves. The ability to determine the reliability of welds depending on the reduction of the area of ​​the welded metal elements increases the operational reliability of metal structures, which for a long time are exploited in aggressive medium.

Method for Describing Fatigue Processes in Structural Materials

2017 ◽  
Vol 265 ◽  
pp. 815-820 ◽  
Author(s):  
V. Mironov ◽  
O. Lukashuk ◽  
D. Vichuzhanin
Keyword(s):  
Experimental Testing ◽  
Testing Machine ◽  
Structural Materials ◽  
Fatigue Process ◽  
Model Predictions ◽  
Degradation Models ◽  
Multiple Cycle ◽  
Strain Stress ◽  
Cyclic Degradation ◽  
Selection Of

The article studies one of the methods for phenomenological description of fatigue processes in structurally-inhomogeneous structural materials. The initial statement about the interrelationship between the static and cyclic material properties is investigated using the complete stress-strain curves or diagrams method (CSSD). Based on the analysis of the mathematic modeling results, the interrelationship is predicted to exist between the highly-localized fatigue process in a structurally-inhomogeneous material and the degradation of a static CSSD for a macroscopic specimen. It is noted that the conditions under which the specimen fails in a testing machine are similar to the ones for the material in a construction. Then the results are given for the direct experimental testing of the model predictions, illustrated with the examples of cyclic degradation of several structural materials. The tests on multiple-cycle fatigued specimens reveal degradation of several mechanical properties. The justification for the selection of the available plasticity of a material as a parameter representative of the fatigue process is given. The authors describe a few examples of building one-parameter cyclic degradation models for steels and some prospects of using the complete strain-stress diagrams for various purposes.

Discrete Particle Methods for Simulating Quasi-Static Load and Hypervelocity Impact Phenomena

2019 ◽  
Vol 16 (05) ◽  
pp. 1740009 ◽  
Author(s):  
Martin O. Steinhauser ◽  
Erkai Watson
Keyword(s):  
High Speed ◽  
Static Load ◽  
Interaction Model ◽  
Hypervelocity Impact ◽  
Particle Methods ◽  
Material Strength ◽  
Model Parameters ◽  
Discrete Particle ◽  
High Speed Impact ◽  
Impact Phenomena

In this paper, we introduce a mesh-free computational model for the simulation of high-speed impact phenomena. Within the framework of particle dynamics simulations we model a macroscopic solid ceramic tile as a network of overlapping discrete particles of microscopic size. Using potentials of the Lennard–Jones type, we integrate the classical Newtonian equations of motion and perform uni-axial, quasi-static load simulations to customize our three model parameters to the typical tensile strength, Young’s modulus and the compressive strength of a ceramic. Subsequently we perform shock load simulations in a standard experimental setup, the edge-on impact (EOI) configuration. Our obtained results concerning crack initiation and propagation through the material agree well with corresponding high-speed EOI experiments with Aluminum Oxinitride (AlON), Aluminum Oxide [Formula: see text] and Silicon Carbide (SiC), performed at the Fraunhofer Ernst-Mach-Institute (EMI). Additionally, we present initial simulation results where we use our particle–based model to simulate a second type of high-speed impact experiments where an accelerated sphere strikes a thin aluminum plate. Such experiments are done at our institute to investigate the debris clouds arising from such impacts, which constitute a miniature model version of a generic satellite structure that is hit by debris in the earth’s orbit. Our findings are that a discrete particle based method leads to very stable, energy-conserving simulations of high–speed impact scenarios. Our chosen interaction model works particularly well in the velocity range where the local stresses caused by impact shock waves markedly exceed the ultimate material strength.

A photoelastic clinical study of the static load distributionat the stump/socket interface of PTB sockets

2005 ◽  
Vol 29 (3) ◽  
pp. 291-302 ◽  
Author(s):  
P. Sewell ◽  
J. Vinney ◽  
S. Noroozi ◽  
R. Amali ◽  
S. Andrews
Keyword(s):  
Clinical Study ◽  
Static Load ◽  
Socket Interface

Analisis Daya Dukung Tanah Dan Bahan Pondasi Tiang Pancang Pada Pembangunan Jembatan Kab. Jombang

2020 ◽  
Vol 9 (1) ◽  
pp. 32-37
Author(s):  
Ruslan Hidayat ◽  
Saiful Arfaah
Keyword(s):  
Carrying Capacity ◽  
Pile Foundation ◽  
Heavy Traffic ◽  
Traffic Volume ◽  
Material Strength ◽  
Cone Penetrometer ◽  
The Village

One of the most important factors in the structure of the pile foundation in the construction of the bridge is the carrying capacity of the soil so as not to collapse. Construction of a bridge in the village of Klitik in Jombang Regency to be built due to heavy traffic volume. The foundation plan to be used is a pile foundation with a diameter of 50 cm, the problem is what is the value of carrying capacity of soil and material. The equipment used is the Dutch Cone Penetrometer with a capacity of 2.50 tons with an Adhesion Jacket Cone. The detailed specifications of this sondir are as follows: Area conus 10 cm², piston area 10 cm², coat area 100 cm², as for the results obtained The carrying capacity of the soil is 60.00 tons for a diameter of 30 cm, 81,667 tons for a diameter of 35 cm, 106,667 tons for a diameter of 40 cm, 150,000 tons for a diameter of 50 cm for material strength of 54,00 tons for a diameter of 30 cm, 73,500 tons for a diameter of 35 cm, 96,00 tons for a diameter of 40 cm, 166,666 tons for a diameter of 50 cm

Masonry: the brittle or plastic material?

2019 ◽  
pp. 22-28
Keyword(s):  
Plastic Material ◽  
Experimental Studies ◽  
Point Of View ◽  
Plastic Properties ◽  
Plastic Deformations ◽  
Base Materials ◽  
Stress States ◽  
Creep Deformations ◽  
Structural Point

The results of experimental studies of masonry on the action of dynamic and static (short-term and long-term) loads are presented. The possibility of plastic deformations in the masonry is analyzed for different types of force effects. The falsity of the proposed approach to the estimation of the coefficient of plasticity of masonry, taking into account the ratio of elastic and total deformations of the masonry is noted. The study of the works of Soviet scientists revealed that the masonry under the action of seismic loads refers to brittle materials in the complete absence of plastic properties in it in the process of instantaneous application of forces. For the cases of uniaxial and plane stress states of the masonry, data on the coefficient of plasticity obtained from the experiment are presented. On the basis of experimental studies the influence of the strength of the so-called base materials (brick, mortar) on the bearing capacity of the masonry, regardless of the nature of the application of forces and the type of its stress state, is noted. The analysis of works of prof. S. V. Polyakov makes it possible to draw a conclusion that at the long application of the load, characteristic for the masonry are not plastic deformations, but creep deformations. It is shown that the proposals of some authors on the need to reduce the level of adhesion of the mortar to the brick for the masonry erected in earthquake-prone regions in order to improve its plastic properties are erroneous both from the structural point of view and from the point of view of ensuring the seismic resistance of structures. It is noted that the proposal to assess the plasticity of the masonry of ceramic brick walls and large-format ceramic stone with a voidness of more than 20% is incorrect, and does not meet the work of the masonry of hollow material. On the basis of the analysis of a large number of research works it is concluded about the fragile work of masonry.

Validation of SST 300 bearing casing for SST 200 bearing casing in static load condition

2011 ◽  
Vol 3 (7) ◽  
pp. 277-278
Author(s):  
Jinesh Shah ◽  
◽  
Mohammad Azim Aijaz ◽  
Pratik Kikani ◽  
Sagarkumar Shah ◽  
...  
Keyword(s):  
Static Load ◽  
Load Condition
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