scholarly journals Determining Optimal Polypropylene Fiber Dosages In Sprayed Concrete For Mining And Civil Engineering Applications

2015 ◽  
Vol 19 (1) ◽  
pp. 81-84 ◽  
Author(s):  
Bayram Kahraman
Keyword(s):  
Energy Absorption ◽  
Load Capacity ◽  
Unit Cost ◽  
Polypropylene Fiber ◽  
Performance Characteristics ◽  
Cost Evaluation ◽  
Experimental Investigations ◽  
Cost Performance ◽  
Sprayed Concrete ◽  
Unit Energy

<p>In this study, experimental investigations were carried out on polypropylene fiber (PF), steel mesh (SM) and PF+SMreinforced shotcrete (RS) panels to evaluate performance characteristics of energy absorption and load capacity. Inaddition to this, material cost evaluation of shotcrete mixtures for unit energy absorption and load capacity has been given.The panel tests, along with the European specification for sprayed concrete (EFNARC), were done on 18 prismaticspecimens having the same mix designs and were cured for 28 days but reinforced at varying fiber dosages. Testresults indicate that in terms of unit cost performance for PF, the best dosages were 2 kg/m³ and 5 kg/m³ respectively.When compared with SM, it was determined that PF is more expensive within the range of 37 - 53%.</p><p> </p><p><strong>Resumen</strong></p>En este estudio se realizaron investigaciones experimentales en fibras de polipropileno, en mallas de acero y en paneles de hormigón proyectado reforzados con fibra de polipropileno y con mallas de acero para evaluar las características de desempeño en absorción de energía y en capacidad de carga. Adicionalmente, se provee una evaluación del costo de materiales en mezlas de hormigón proyectado por unidad de absorción de energía y por capacidad de carga. Los exámenes en paneles, con las especificaciones europeas para hormigón proyectado (EFNARC, inglés), se realizaron en 18 muestras prismáticas con los mismos diseños de mezcla y se curaron por 28 días con refuerzos de diferentes dosis de fibras. Los resultados de la evaluación indican que, en términos de desempeño por unidad de costo para fibras de polipropileno, las mejores dosis fueron 2 kg/m3 y 5 kg/m3, respectivamente. Cuando se comparó con las mallas de acero, se determinó que las fibras de polipropileno son entre el 37 % y el 53 % más caras.

scholarly journals Analysis of the Welding Type and Filler Metal Influence on Performance of a Regenerated Gear

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1496
Author(s):  
Svetislav Marković ◽  
Dušan Arsić ◽  
Ružica R. Nikolić ◽  
Vukić Lazić ◽  
Nada Ratković ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Service Life ◽  
Economic Analysis ◽  
Filler Metal ◽  
Performance Characteristics ◽  
Experimental Investigations ◽  
Spur Gears ◽  
Soft Filler ◽  
Welding Procedure

This paper presents the results of voluminous experimental investigations conducted to analyze the influence of the welding procedure on the performance of regenerated gears. Cylindrical spur gears were tested, both newly manufactured and regenerated, in two fundamentally different ways: by hard facing (surfacing) with the “hard” filler metal (DUR 600-IG) and with the “soft” filler metal (EVB2CrMo) with subsequent cementation and quenching. The regeneration procedures were defined and executed, while, subsequently, the microstructure and microhardness of the hard-faced layers were established and measured, followed by checking the durability of the hard-faced teeth flanks. Finally, techno-economic analysis was performed to establish the rationality of the conducted regenerations, i.e., the costs of regenerated and newly manufactured teeth were compared. Based on the results of the conducted investigations, it was possible to establish the influence of the welding type on the performance characteristics (primarily the service life) of the regenerated gears. For individual reparatory hard facing, the procedure with the “hard” filler metal exhibited better characteristics, while for batch reparation of numerous damaged gears, the reparation with the “soft” filler metal, followed by cementation and heat treatment, might be more convenient.

Influence of different flow regimes on the performance characteristics of a four-pad hydrostatic squeeze film damper loaded between pads

2019 ◽  
Vol 71 (3) ◽  
pp. 440-446
Author(s):  
Amina Nemchi ◽  
Ahmed Bouzidane ◽  
Aboubakeur Benariba ◽  
Hicham Aboshighiba
Keyword(s):  
Turbulent Flow ◽  
Load Capacity ◽  
Flow Regimes ◽  
Performance Characteristics ◽  
Squeeze Film ◽  
Eccentricity Ratio ◽  
Flow Conditions ◽  
Content Type ◽  
Turbulent Flow Regime ◽  
Squeeze Film Dampers

Purpose The purpose of this paper is to study the influence of different flow regimes on the dynamic characteristics of four-pad hydrostatic squeeze film dampers (SFDs) loaded between pads. Design/methodology/approach A numerical model based on Constantinescu’s turbulent lubrication theory using the finite difference method has been developed and presented to study the effect of eccentricity ratio on the performance characteristics of four-pad hydrostatic SFDs under different flow regimes. Findings It was found that the influence of turbulent flow on the dimensionless damping of four-pad hydrostatic SFDs appears to be essentially controlled by the eccentricity ratio. It was also found that the laminar flow presents higher values of load capacity compared to bearings operating under turbulent flow conditions. Originality/value In fact, the results obtained show that the journal bearing performances are significantly influenced by the turbulent flow regime. The study is expected to be useful to bearing designers.

scholarly journals Evaluation of Steel Fiber–Reinforced Sprayed Concrete by Energy Absorption Tests

2021 ◽  
Vol 33 (9) ◽  
pp. 04021252
Author(s):  
Alan Renato Estrada Cáceres ◽  
Sergio Henrique Pialarissi Cavalaro ◽  
Antonio Domingues de Figueiredo
Keyword(s):  
Energy Absorption ◽  
Steel Fiber ◽  
Fiber Reinforced ◽  
Sprayed Concrete

Lubrication of Porous Journal Bearings

1972 ◽  
Vol 94 (1) ◽  
pp. 69-73 ◽  
Author(s):  
C. Cusano
Keyword(s):  
Analytical Solution ◽  
Coefficient Of Friction ◽  
Load Capacity ◽  
Journal Bearings ◽  
Performance Characteristics ◽  
Eccentricity Ratio ◽  
Design Variables

An analytical solution for the performance characteristics of finite porous journal bearings is obtained. Results are presented which relate the eccentricity ratio and coefficient of friction as functions of load number for design variables of 0.0001, 0.001, 0.01, and 0.1. The load capacity obtained by using the finite bearing theory is compared to the load capacity obtained by using the short-bearing approximation and the infinite-bearing approximation.

Simulation studies on static thermal behaviour of true elliptical and orthogonally displaced non-circular journal bearing

2016 ◽  
Vol 68 (3) ◽  
pp. 349-360 ◽  
Author(s):  
Amit Singla ◽  
Amit Chauhan
Keyword(s):  
Journal Bearing ◽  
Load Capacity ◽  
Current Trend ◽  
Operating Conditions ◽  
Performance Characteristics ◽  
Film Pressure ◽  
Content Type ◽  
Oil Film ◽  
Ellipticity Ratio ◽  
Oil Film Pressure

Purpose The current trend of modern industry is to use machineries which rotate at high speed along with the capability of carrying heavy rotor loads. This paper aims at static thermal analysis of two different profiles of non-circular journal bearings – a true elliptical bearing and orthogonal bearing. Design/methodology/approach The Reynolds equation has been solved through finite difference method to compute the oil film pressure. Parabolic temperature profile approximation technique has been used to solve the energy equation and thus used for computation of various bearing performance characteristics such as thermo-hydrodynamic oil film pressure, temperature, load capacity, Sommerfeld number and power loss characteristics across the bearing. The effect of ellipticity ratio on the bearing performance characteristics has also been obtained for both the elliptical and vertical offset bearing using three different commercially available grades of oil (Hydrol 32, 68 and 100). Findings It has been observed that the thermo-hydrodynamic pressure and temperature rise of the oil film is less in orthogonal bearing as compared to the true elliptical bearing for same operating conditions. The effect of ellipticity ratio of non-circularity on bearing performance parameters have been observed to be less in case of elliptical bearing as compared to orthogonal bearing. It has been concluded that though the rise in oil film temperature is high for true elliptical bearing, but still it should be preferred over orthogonal profile under study, as it has comparably good load-carrying capacity. Originality/value The performance parametric analysis will help the designers to select such kind of non-circular journal bearing for various applications.

Influence of the Parameter of Ductility of Reinforcing Steel on the Behaviour of a Narrow Three-Span Reinforced Concrete Slab Based on Experimental Investigations

2015 ◽  
Vol 240 ◽  
pp. 218-224 ◽  
Author(s):  
Mirosław Wieczorek
Keyword(s):  
Reinforced Concrete ◽  
Concrete Slab ◽  
Load Capacity ◽  
Experimental Tests ◽  
Experimental Investigations ◽  
Building Structures ◽  
Reinforced Concrete Slab ◽  
Tension Member ◽  
Test Models ◽  
Reinforced Steel

In the time of the exploitation of building structures frequently situations do occur, in which due to failures they are exposed to much higher loads than has been originally predicted. In a state of emergency due to overloading of the structure, significant reserves of load capacity may be appear in the case of a self-acting tension member work. The aim of the paper was to demonstrate the influence of reinforced steel parameters and its quantity on the mechanism of destruction of four three-span models of reinforced concrete strips with the dimensions 7140×500×190 mm. The paper contains the description of the test stand and test models and the results of experimental tests which were compared with the results of the calculations based on traditional methods.

A Numerical Study on the Ultimate Strength of Damaged Tubular Bracing Members Under Axial Compression

2018 ◽  
Author(s):  
Ling Zhu ◽  
Jieling Kong ◽  
Qingyang Liu ◽  
Han Yang ◽  
Bin Wang
Keyword(s):  
Ultimate Strength ◽  
Axial Compression ◽  
Numerical Study ◽  
Load Capacity ◽  
Approximate Equation ◽  
Offshore Structures ◽  
Experimental Investigations ◽  
Pipe Length ◽  
Axial Load Capacity ◽  
Parametric Studies

The tubular bracing members of offshore structures may sustain collision damages from the supply ships, which lead to the deterioration of the load carrying capacity of tubular bracing members. This paper presents a numerical simulation of the ultimate strength of damaged tubular bracing members under axial compression with the nonlinear finite element code ABAQUS, based on previous experimental investigations. Parametric studies are conducted to investigate the load capacity of damaged tubular bracing members, by considering the effects of diameter (D), wall thickness (H), pipe length (L) and the damage positions on the ultimate strength of tubular members. It is found that lateral damage can cause great reduction of the axial load capacity of tubular members. In addition, an approximate equation to predict the ultimate strength of tubular members based on the given damage depth is proposed.

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