scholarly journals The new tool insert design for prevention the rotation of horizontal wire during shear testing of welded fabric

10.30544/425 ◽  
2019 ◽  
Vol 25 (2) ◽  
pp. 163-170
Author(s):  
Ivana Atanasovska ◽  
Dejan Momčilović ◽  
Ognjen Ristić
Keyword(s):  
Shear Strength ◽  
Civil Engineering ◽  
Strength Properties ◽  
Test Methods ◽  
Repeated Testing ◽  
Element Analysis ◽  
Tool Insert ◽  
Steel Metallurgy ◽  
Accuracy Of Results ◽  
The Impact

Many new requirements in the field of experimental mechanics, like testing of metallic materials, emphasize traceability and accuracy of test results as the end goal. These requirements have energy efficiency context too, due to the increase of mass productions of many finished and semi-finished products based on steel metallurgy. Combined, both of the above-noted perspectives impose the need for improvements of some of the existing test methods. This paper describes one such improvement, the developing of the new insert tool for testing of shear strength of the welded fabric, for civil engineering. The developed tool allows repeated testing of welded joints sampled from the welded fabric of different dimensions without tool changes and is generally related with the procedure for the determination of shear strength properties of different sizes of wires used for welded fabric. The construction of the tool insert allows aiming high operation safety and higher accuracy of results, which is described in detail. The paper also presents experimental results and the Finite Element Analysis performed in order to verify the impact of insert tool application on the testing results. The obtained results and conclusion about the possible contributions of the developed insert tool for extensively testing of welded fabric for civil engineering are discussed.

scholarly journals Development of the universal tool for testing of tensile properties of hexagonal steel wire mesh for civil engineering

10.30544/365 ◽  
2018 ◽  
Vol 24 (2) ◽  
pp. 113-122
Author(s):  
Ivana Atanasovska ◽  
Dejan Momčilović ◽  
Milorad Gavrilovski
Keyword(s):  
Tensile Properties ◽  
Civil Engineering ◽  
Steel Wire ◽  
Strength Properties ◽  
Wire Mesh ◽  
Repeated Testing ◽  
Element Analysis ◽  
Safety Testing ◽  
Steel Wire Mesh ◽  
Wire Meshes

The developing of the universal tool for testing of tensile properties of hexagonal steel wire mesh for civil engineering is described in this paper. The developed tool allows repeated testing of hexagonal steel wire mesh of different dimensions without tool changes and is generally related with the procedure for the determination of tensile strength properties of different wire meshes. The construction of the tool which is related to the aims of the decreased mass consumption and high operation safety is described in detail. Particular attention is focused on the safety component of the tool which ensuring safety testing by preventing slipping of the wire mesh samples during loading. The paper also presents the Finite Element Analysis performed in order to verify the high safety factor of the developed tool. The contact regions with stress concentration behavior are analyzed by non-linear solvers. The obtained results and conclusion about the possible contributions of the developed universal tool for extensively testing of wire meshes for civil engineering are discussed.

scholarly journals An impact echo method to detect cavities between railway track slabs and soil foundation

2021 ◽  
Vol 68 (1) ◽  
Author(s):  
Pierre Anthyme Bahati ◽  
Viet Dinh Le ◽  
Yujin Lim
Keyword(s):  
Open Space ◽  
Concrete Slab ◽  
Test Methods ◽  
Railway Track ◽  
Element Analysis ◽  
Impact Echo ◽  
Time Frequency ◽  
Railway Tracks ◽  
Soil Foundation ◽  
The Impact

AbstractThe impact echo technique is one of the most useful non-destructive test methods for determining the thickness of concrete or detecting possible cracks or cavities in the internal parts of a concrete structure without damaging the surface. Many types of unstable conditions in railway tracks, including various modes of irregularities, may occur when cavities are generated directly under a concrete slab track or when a slight open space is made under a loose sleeper. In this study, we developed a nondestructive testing (NDT) system for detecting abnormalities in concrete tracks and performed 3D numerical simulations using the ABAQUS finite element analysis (FEA) program to investigate the impact echo response from a concrete track slab with different sizes of cavities. Sections of concrete slab were simulated as solid body masses under the railway tracks with gaps in the bodies themselves or with cavities existing between the track concrete layer (TCL) and the hydraulically stabilized base (HSB). We investigated the locations and depths of the cavities and gaps in the model concrete slab using the acoustic impact echo response based on the frequency response of the elastic waves generated in the slab. In addition, a Short-time Fourier Transform (STFT) and a wavelet technique were adopted for a time frequency analysis. Our study demonstrated that the impact echo technique developed in this study by FEA and NDT can measure and confirm the location and depth of cavities in concrete slabs.

scholarly journals Leaching Impact on Compressibility and Shear Strength of Undisturbed and Cement-treated Champlain Sea Clay

2021 ◽  
Author(s):  
Mohammad Afroz
Keyword(s):  
Shear Strength ◽  
Triaxial Compression ◽  
Strength Properties ◽  
Experimental Results ◽  
Salinity Level ◽  
Compression Tests ◽  
Treated Sample ◽  
Salinity Levels ◽  
Geotechnical Tests ◽  
The Impact

This research investigated the impact of leaching on the compressibility and shear strength properties of undisturbed and cement-treated Champlain Sea clay. A total of five undisturbed clay samples were leached with distilled water in the laboratory to reduce the salinity from initial values ranging from 9.5 to 15 g/L to the salinity values of 2.75, 1.45, 1.03, 0.55, and 0.35 g/L. A series of geotechnical tests were conducted on these samples at different salinity levels, including constant rate of strain consolidation tests, consolidated isotropic undrained triaxial compression tests, and vane shear tests. The experimental results showed that leaching leads to an increase in the compressibility and a reduction in shear strength of undisturbed Champlain Sea clay. The experimental results revealed that cement, mixed at a dosage of 50 kg/m3 , can significantly decrease the compressibility and increase the shear strength of Champlain Sea clay. A leached cement-treated sample exhibits a relatively higher compressibility than that of unleached cementtreated one. An increase in compressibility was also observed as salinity declines for the cementtreated samples. Moreover, a cement-treated sample at a lower salinity level displays slightly a higher shear strength compared to that of a cement-treated sample at the original salinity level.

scholarly journals The effect of chip size and alkaline pre-hydrolysis conditions on following soda pulping of hornbeam wood

2019 ◽  
Vol 70 (4) ◽  
pp. 329-336
Author(s):  
Ahmad Jahan Latibari ◽  
Abdulrahim Mohebalian ◽  
Ajang Tajdini ◽  
Shadman Pourmosua
Keyword(s):  
Lignin Content ◽  
Total Yield ◽  
Strength Properties ◽  
Test Methods ◽  
Standard Test ◽  
Cellulose Content ◽  
Hemicellulose Removal ◽  
Soda Pulping ◽  
Chip Size ◽  
The Impact

The impact of chip size and hydrolysis temperature on changing chemical composition of hornbeam wood and following soda pulping is investigated. Three chip sizes, two temperatures (60 and 90 °C) and 120 minutes retention time in pre-hydrolysis step were selected. After pre-hydrolysis treatment, the sample was divided into two portions; one third was used for chemical analysis and the other two thirds for soda pulping. The reference soda pulping conditions were used on either treated or untreated chips. The influence of pre-hydrolysis was determined measuring cellulose and lignin content, residual alkali and the hemicelluloses removal. The lignin and cellulose content were marginally increased and the hemicellulose removal was higher at larger chip size. Total yield and rejects, kappa number and strength properties of the unbleached pulp were measured using corresponding Tappi standard test methods. The pulping total yield and rejects of the treated chips varied between 30.31 % and 48.14 % and 0.83 % to 7.31 %, respectively. The reject from soda pulping of untreated chips was 24.16. Prehydrolysis treatment reduced the tensile index, but the tear index was only marginally improved.

scholarly journals GIS-based topographic reconstruction and geomechanical modelling of the Köfels Rock Slide

2020 ◽  
Author(s):  
Christian Zangerl ◽  
Annemarie Schneeberger ◽  
Georg Steiner ◽  
Martin Mergili
Keyword(s):  
Shear Strength ◽  
Groundwater Flow ◽  
Friction Angle ◽  
High Water ◽  
Strength Properties ◽  
Trigger Factor ◽  
Rock Slide ◽  
Low Friction ◽  
Volume Estimates ◽  
The Impact

Abstract. The Köfels Rock Slide in the Ötztal Valley (Tyrol, Austria) represents the largest known extremely rapid landslide in metamorphic rock masses in the Alps. Although many hypotheses for the trigger were discussed in the past, until now no scientifically proven trigger factor has been identified. This study provides new data about the i) pre-failure and failure topography, ii) failure volume and porosity of the sliding mass, and iii) shear strength properties of the gneissic rock mass obtained by back-calculations. Geographic information system methods were used to reconstruct the slope topographies before, during and after the event. Comparing the resulting digital terrain models leads to volume estimates of the failure and deposition masses of 3.1 km3 and 4.0 km3, respectively and a sliding mass porosity of 26 %. For the back-calculations the 2D discrete element method was applied to determine the shear strength properties of the reconstructed basal shear zone. Results indicated that under no groundwater flow conditions, a very low friction angle below 24° is required to promote failure, whilst, with groundwater flow, the critical value increase to 28°. Such a low friction angle is unexpected from a rock mechanical perspective for this strong rock and groundwater flow, even if high water pressures are assumed, may not be able to trigger this rock slide. Additional conditioning and triggering factors should be identified by further studies, for example focussing on the impact of dynamic loading.

scholarly journals Leaching Impact on Compressibility and Shear Strength of Undisturbed and Cement-treated Champlain Sea Clay

2021 ◽  
Author(s):  
Mohammad Afroz
Keyword(s):  
Shear Strength ◽  
Triaxial Compression ◽  
Strength Properties ◽  
Experimental Results ◽  
Salinity Level ◽  
Compression Tests ◽  
Treated Sample ◽  
Salinity Levels ◽  
Geotechnical Tests ◽  
The Impact

This research investigated the impact of leaching on the compressibility and shear strength properties of undisturbed and cement-treated Champlain Sea clay. A total of five undisturbed clay samples were leached with distilled water in the laboratory to reduce the salinity from initial values ranging from 9.5 to 15 g/L to the salinity values of 2.75, 1.45, 1.03, 0.55, and 0.35 g/L. A series of geotechnical tests were conducted on these samples at different salinity levels, including constant rate of strain consolidation tests, consolidated isotropic undrained triaxial compression tests, and vane shear tests. The experimental results showed that leaching leads to an increase in the compressibility and a reduction in shear strength of undisturbed Champlain Sea clay. The experimental results revealed that cement, mixed at a dosage of 50 kg/m3 , can significantly decrease the compressibility and increase the shear strength of Champlain Sea clay. A leached cement-treated sample exhibits a relatively higher compressibility than that of unleached cementtreated one. An increase in compressibility was also observed as salinity declines for the cementtreated samples. Moreover, a cement-treated sample at a lower salinity level displays slightly a higher shear strength compared to that of a cement-treated sample at the original salinity level.

Does kraft hardwood and softwood pulp viscosity correlate to paper properties?

TAPPI Journal ◽  
2016 ◽  
Vol 15 (10) ◽  
pp. 643-651 ◽  
Author(s):  
ROBERT J. OGLESBY ◽  
HUMPHREY J. MOYNIHAN ◽  
RICARDO B. SANTOS ◽  
ASHOK GHOSH ◽  
PETER W. HART
Keyword(s):  
Physical Properties ◽  
Strength Loss ◽  
Strength Properties ◽  
Clear Correlation ◽  
Paper Properties ◽  
Physical Strength ◽  
Pulp Viscosity ◽  
Softwood Pulp ◽  
The Impact ◽  
Related Paper

The impact of commercially prepared, fully bleached pulp viscosity variation on handsheet physical properties was evaluated at different levels of pulp refining. Hardwood pulps from the same brownstock species mix, cooking parameters, and kappa numbers were processed through two different commercial bleach plants: one with a D0(EP)D1D2 sequence and the second with an OD0(EOP)D1 sequence. Additionally, a commercial softwood (predominately Scotts pine) brownstock pulp bleached by an OD0(EP)D1D2 sequence was employed in this study. Pulps with viscosities ranging from 14 to 21 mPa∙s were refined in a Valley beater to two freeness levels, and the associated handsheet physical properties were measured in this study. Over the pulp viscosity range of 14 to 21 mPa∙s, no clear correlation was found to exist between pulp viscosity and related paper physical properties. Finally, a series of laboratory prepared bleached pulps were purposely prepared under non-ideal conditions to reduce their final viscosities to lower values. Handsheets made from these pulps were tested in their unbeaten condition for physical strength properties. Significant and rapid strength loss occurred when the measured pulp viscosity dropped below 12 mPa∙s; overall strength properties showed no correlation to viscosity above the critical 12 mPa∙s value.

Evaluation of Hydraulic Fracturing Models and Their Limitations to Predict No-Drill Zones for Horizontal Directional Drilling

2018 ◽  
Author(s):  
Saeed Delara ◽  
Kendra MacKay
Keyword(s):  
Hydraulic Fracturing ◽  
Safety Factor ◽  
Standard Procedure ◽  
Accurate Determination ◽  
Strength Properties ◽  
Analytical Models ◽  
Alternative Methods ◽  
Directional Drilling ◽  
Horizontal Directional Drilling ◽  
The Impact

Horizontal directional drilling (HDD) has become the preferred method for trenchless pipeline installations. Drilling pressures must be limited and a “no-drill zone” determined to avoid exceeding the strength of surrounding soil and rock. The currently accepted industry method of calculating hydraulic fracturing limiting pressure with application of an arbitrary safety factor contains several assumptions that are often not applicable to specific ground conditions. There is also no standard procedure for safety factor determination, resulting in detrimental impacts on drilling operations. This paper provides an analysis of the standard methods and proposes two alternative analytical models to more accurately determine the hydraulic fracture point and acceptable drilling pressure. These alternative methods provide greater understanding of the interaction between the drilling pressures and the surrounding ground strength properties. This allows for more accurate determination of horizontal directional drilling limitations. A comparison is presented to determine the differences in characteristics and assumptions for each model. The impact of specific soil properties and factors is investigated by means of a sensitivity analysis to determine the most critical soil information for each model.

scholarly journals Potential and limitations of finite element modelling in assessing structural integrity of coralline algae under future global change

2015 ◽  
Vol 12 (19) ◽  
pp. 5871-5883 ◽  
Author(s):  
L. A. Melbourne ◽  
J. Griffin ◽  
D. N. Schmidt ◽  
E. J. Rayfield
Keyword(s):  
Climate Change ◽  
Finite Element ◽  
Structural Integrity ◽  
Geometric Model ◽  
Algal Growth ◽  
Coralline Algae ◽  
Rocky Shores ◽  
Element Analysis ◽  
Scan Data ◽  
The Impact

Abstract. Coralline algae are important habitat formers found on all rocky shores. While the impact of future ocean acidification on the physiological performance of the species has been well studied, little research has focused on potential changes in structural integrity in response to climate change. A previous study using 2-D Finite Element Analysis (FEA) suggested increased vulnerability to fracture (by wave action or boring) in algae grown under high CO2 conditions. To assess how realistically 2-D simplified models represent structural performance, a series of increasingly biologically accurate 3-D FE models that represent different aspects of coralline algal growth were developed. Simplified geometric 3-D models of the genus Lithothamnion were compared to models created from computed tomography (CT) scan data of the same genus. The biologically accurate model and the simplified geometric model representing individual cells had similar average stresses and stress distributions, emphasising the importance of the cell walls in dissipating the stress throughout the structure. In contrast models without the accurate representation of the cell geometry resulted in larger stress and strain results. Our more complex 3-D model reiterated the potential of climate change to diminish the structural integrity of the organism. This suggests that under future environmental conditions the weakening of the coralline algal skeleton along with increased external pressures (wave and bioerosion) may negatively influence the ability for coralline algae to maintain a habitat able to sustain high levels of biodiversity.

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