scholarly journals Stress–Strain Behaviour of Reparable Composite Panel with Step-Variable Thickness

Polymers ◽  
2021 ◽  
Vol 13 (21) ◽  
pp. 3830
Author(s):  
Andrii Kondratiev ◽  
Václav Píštěk ◽  
Lina Smovziuk ◽  
Maryna Shevtsova ◽  
Anna Fomina ◽  
...  
Keyword(s):  
Bearing Capacity ◽  
Variable Thickness ◽  
Transverse Shear ◽  
Repair Process ◽  
Composite Panel ◽  
Engineering Practice ◽  
Shear Deformations ◽  
Stress Strain ◽  
Bonded Repair ◽  
Strain Behaviour

There is an urgent problem of finding an economically viable method of maintenance and restoration of the bearing capacity of structures of various applications. Repair of structures with patches made of polymeric composite materials is one of the most promising repair technologies. However, an improper choice of parameters of the composite patch leads to unjustified increase in the structure mass and the cost of its further operation. These situations result from the lack of reliable methods for developing the repair process, which take into account the influence of the patch geometry and conditions for performance of repair works on the bearing capacity of the repaired structure. The mathematical model of the reparable composite shell–type panel taking into account inhomogeneity of transverse shear deformations at stepped variation of its thickness has been developed. In contrast to the classical theory of layered shells, the model allows simplifying a three-dimensional problem by setting of the displacement field on the layers’ interfaces and their linear interpolation over thickness of the panel, as well as considering the transverse shear deformations resulting from the strength, temperature, or shrinkage loading. According to results, the maximum rise in stresses in the case of a notched panel occurs in the weakened layer, and it is from this layer the failure of the structure will start. In the event of the patch, the panel surface opposite the reinforcement is the most loaded (i.e., susceptible to failure) surface. To confirm the reliability of the developed model, we compared the analytical calculations with the results of experimental and numerical studies of the deformed state of a panel of step–variable thickness by the method of holographic interferometry and modelling by the finite element method. Displacement fields available from experiments correspond to the predicted theoretical results. The resulting maximum error does not exceed 7%. The data obtained during numerical modelling allowed us to conclude that the accuracy of theoretical calculations is sufficient for engineering practice. Results of the work can be used to solve the practical problems such as determination of stress–strain behaviour of a damaged structure or structure after repair, specification of the permissible delamination dimensions, and defining of parameters of the bonded repair process.

Effect of the Loading rate on the Tensile strength of Concrete

1985 ◽  
Vol 64 ◽  
Author(s):  
Michal A. Glinicki
Keyword(s):  
Tensile Strength ◽  
Loading Rate ◽  
Considerable Importance ◽  
Engineering Practice ◽  
Reinforcing Steel ◽  
Bond Properties ◽  
Shear Forces ◽  
Stress Strain ◽  
Strain Behaviour ◽  
Impulsive Loads

The knowledge of the loading rate influence on the tensile strength of concrete is of considerable importance in engineering practice. The safety of several concrete structures subjected to impact and impulsive loads is often controlled by the tensile strength and stress-strain behaviour because these properties greatly influence the cracking of concrete, bond properties of reinforcing steel and behaviour under shear forces.

scholarly journals Comparative Study in Method of Compaction by Consolidated Drained and Direct Shear Test

2020 ◽  
Vol 78 (2) ◽  
pp. 143-152
Author(s):  
Abdul Samad Abdul Rahman ◽  
N. Sidek ◽  
Juhaizad Ahmad ◽  
N. Hamzah ◽  
M. I. F. Rosli
Keyword(s):  
Shear Strength ◽  
Bearing Capacity ◽  
Triaxial Test ◽  
Direct Shear Test ◽  
Shear Test ◽  
Void Ratio ◽  
Direct Shear ◽  
Test Results ◽  
Stress Strain ◽  
Strain Behaviour

Soil compaction has been a common practice in the construction of highways, embankments, earth dams and other related structures where the condition of the soil is high in void ratio and therefore having a very low in bearing capacity. Therefore, the soil needs to be compacted in order to minimize the void ratio and in the same time would results in having a very high bearing capacity to sustain load. Nevertheless, only a few researches have been done to investigate the method of compaction using different energy on the behavior of shear strength by consolidated drained and direct shear test. In this research, the effect of different compaction in energy of 25 number of blows compared to 40 number of blows on the stress-strain behaviour of drained triaxial test has been done and findings of the data are to be compared with direct shear test. Results reveal that there is an increase in soil unit weight by using different energy in compaction with an increase of 5% from 1790 kg/m3 to 1880 kg/m3 for 25 and 40 number of blows respectively. However, the stress-strain behaviour of the specimens shows differently when compared between consolidated drained triaxial and direct shear test. The shear strength for direct shear-stress is at higher value compared to drained triaxial test. For drained triaxial test, results reveal that the effective friction angles are increase only about 1% from 37° to 38°. This is due to the soil particles rearranging itself with the different applied pressures thus eliminating the effects of different energy on the shear strength of the specimens. However, for direct shear test, the shear strength increases drastically from 29° to 32°. The increase of the shear strength is more likely influence by the soil particle arrangement due to the impact of the energy of the no of blows to the desired specimen.

ENGINEERING PROCEDURE FOR EVALUATING THE LOAD-BEARING CAPACITY AND LIFE OF A DEFECTIVE STRUCTURE

2020 ◽  
pp. 36-49
Author(s):  
Aleksey N. SOFINSKIY
Keyword(s):  
Fracture Mechanics ◽  
Bearing Capacity ◽  
Material Properties ◽  
Operating Conditions ◽  
Engineering Practice ◽  
Stress Strain ◽  
Load Bearing Capacity ◽  
Defective Structure ◽  
Load Bearing ◽  
Manufacturing Defects

A piece of rocket and space hardware may consist of tens of thousands of parts. Virtually every as-built piece of hardware has some non-conformances to the design documentation. Manufacturing defects often occur or are discovered during the final stages of the vehicle assembly or pre-launch processing. In such cases, removal of the non-conformance is either impossible or is too difficult and costly. The procedure described in the paper makes it possible to evaluate the degree of impact of a typical defect on the load-bearing capacity, strength, leak integrity, and life of a structure under its operating conditions. Sections of the procedure include description of operations involving non-destructive testing, determining loads on the vehicle and other operating conditions, stress-strain analysis, experimental determination of the material properties, prediction of the crack kinetics from the standpoint of fracture mechanics. The procedure gives a structural analyst an algorithm for solving the complex problem of estimating the service life, which consists of a sequence of specific tasks: developing the finite element model, classifying the defect, constructing the loading block, analyzing stress-strain behavior, predicting the behavior of the initial defect. Introducing the procedure into engineering practice will make it possible to increase validity of the estimate of the load bearing capacity and life, and, therefore, of the reliability and safety of the vehicle operation. Key words: structure, defect, crack, loads, stress condition, material properties, fracture mechanics, strength, leak integrity, life.

Lamellar Tearing Observations Regarding the Application of European Standards in the Field of Welded Steel Constructions

2018 ◽  
Vol 69 (6) ◽  
pp. 1352-1354
Author(s):  
Anamaria Feier ◽  
Oana Roxana Chivu
Keyword(s):  
Bearing Capacity ◽  
Brittle Failure ◽  
Engineering Practice ◽  
Steel Bridge ◽  
Railway Bridge ◽  
Welded Steel ◽  
Direct Replacement ◽  
Lamellar Tearing ◽  
European Standards ◽  
Comprehensive Study

The problem of corrosion for old steel bridges in operation is often solved by direct replacement of elements or structure. Only a few studies have been done to determine the efforts influenced by corrosion in those elements. In general, it is considered that a corroded element has exceeded the bearing capacity and should be replaced, but if the corroded element is secondary it could be treated and kept. A factor in the rehabilitation of an old steel bridge in operation is the aspect of structure. If the structure is corroded, rehabilitation decision is taken is easier. Lamellar tearing describes the cracking that occurs beneath the weld and can be characterized as a brittle failure of steel, in the direction perpendicular to the plane of rolling. The paper presents a comprehensive study on lamellar tearing and summarizes some conclusions about the prevention of them. The conclusions will be exemplified in the case of a railway bridge, with a main truss girder. The paper presents also some observations regarding the stress analysis in fillet welds, resulting from the engineering practice.

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