Effectiveness of CFRP composites on compression flange of structural I-beam

2019 ◽  
Vol 17 (4) ◽  
pp. 782-792
Author(s):  
Prashant Rangrao Jagtap ◽  
Sachin M. Pore
Keyword(s):  
Carrying Capacity ◽  
Steel Structures ◽  
Local Failure ◽  
Elastic Behavior ◽  
Steel Beams ◽  
Load Carrying Capacity ◽  
Content Type ◽  
Cfrp Laminates ◽  
Load Carrying ◽  
Strengthened Beam

Purpose This study aims to use carbon fiber-reinforced polymer (CFRP) laminates to strengthen the compression flange of structural I-beam so as to avoid local failure of compression flange and to take a load to its full capacity. Light weight beam (LB) 100 at 5.1 kg/m and LB 115 at 8.1 kg/m are used for this purpose. The compression flange of a beam is well prepared to ensure a rust-free surface so as to achieve proper bonding between the flange and fiber sheet to avoid de-bonding at the time of testing. A flange of the beam is strengthened using CFRP sheets applied to it with the help of adhesive. The beam with CFRP is cured in air for 48 h before testing. Experiments are performed in a loading frame of 100 T capacity. Results show that the load carrying capacity of the strengthened beam increased by 25-30 per cent compared to the control beam (non-strengthened), and the local failure of the compression flange due to the applied load is totally avoided. The elastic behavior of the strengthened beam is also increased compared to the non-strengthened beam, which gives a higher yield point. Design/methodology/approach Different methods exist for strengthening various structures. Use of CFRP appears to be an excellent solution. Vast research has been conducted on the use of CFRP for strengthening and retrofitting of steel structures. The load carrying capacities of steel beams can be increased by strengthening their compression flange by using CFRP and avoiding the local failure of beams at early stages. Findings The load carrying capacity of a beam strengthened with CFRP increased by 25-30 per cent compared to the non-strengthened beam. In addition, the elastic behavior of the strengthened beam is also improved. Originality/value The compression flange of the steel beam is strengthened using different layers of CFRP strips to avoid the local failure, and its deflection is observed using linear variable deformation transducer.

Parametric study of truss bridges by the post-tensioning method

2005 ◽  
Vol 32 (2) ◽  
pp. 420-429 ◽  
Author(s):  
Kyoung-Bong Han ◽  
Sun-Kyu Park
Keyword(s):  
Carrying Capacity ◽  
Steel Structures ◽  
High Strength ◽  
Elastic Behavior ◽  
Design Parameters ◽  
Load Carrying Capacity ◽  
Prestressing Force ◽  
Load Carrying ◽  
Post Tensioning ◽  
Post Tensioned

The post-tensioning method has been successfully used to improve the performance of existing concrete structures. Applications of the method are rare in steel structures, however. Post-tensioning using high-strength cables or bars can be effectively used to increase the working load carrying capacity of steel structures. In this paper, the elastic behavior of post-tensioned trusses with straight and draped tendon profiles for truss strengthening is examined. The effects of design parameters such as the tendon profile, truss type, prestressing force, and tendon eccentricity on working load and deflection of trusses are studied. The results show that the allowable load of a truss increases proportionally with the increase in prestressing force and eccentricity. Post-tensioning enlarges the elastic range, increases the redundancy, and reduces the deflection and member stresses, eventually increasing the load-carrying capacity of truss bridges.Key words: post-tensioning method, steel structures, post-tensioned trusses, truss strengthening, design parameters, load-carrying capacity.

Flexural strengthening of pre-cracked RC slabs with prestressed NSM CFRP laminates and evaluation of strain loss

2021 ◽  
pp. 136943322110105
Author(s):  
M.R. Mostakhdemin Hosseini ◽  
Salvador J.E. Dias ◽  
Joaquim A.O. Barros
Keyword(s):  
Carrying Capacity ◽  
Load Carrying Capacity ◽  
Limit States ◽  
Transfer Length ◽  
Rc Structures ◽  
Cracked Concrete ◽  
Flexural Strengthening ◽  
Cfrp Laminates ◽  
Load Carrying ◽  
Rc Slabs

The strengthening intervention of RC structures often involves already cracked concrete. To evaluate the effect of the level of damage prior to the strengthening (pre-cracks) on the behavior of the flexurally strengthened RC slabs with prestressed NSM CFRP laminates, an experimental research was carried out. Two pre-cracking levels of damage were analyzed and, for each one, three levels of prestress were tested (0%, 20% and 40%). The obtained results showed that the strengthening of damaged RC slabs with prestressed NSM CFRP laminates results in a significant increase on the load carrying capacity at serviceability limit states. Pre-cracked RC slabs strengthened with prestressed NSM CFRP laminates presented a load carrying capacity almost similar to the corresponding uncracked strengthened slabs. To determine the effective prestress level in CFRP laminates, the variation of strain over the length of the CFRP and over time was experimentally recorded. The prestress transfer length was also evaluated. The experimental results revealed that the transfer length of CFRP laminates was less than 150 mm, and the maximum value of strain loss out of transfer length (around 14%) was measured close to the cracked section of the damaged RC slabs. Significant part of strain loss in CFRP laminates occurred during 24 h after releasing the prestress load.

Numerical investigation of squeeze film lubrication on bioinspired hexagonal patterned surface

2022 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Binbin Su ◽  
Xianghe Zou ◽  
Lirong Huang
Keyword(s):  
Flow Rate ◽  
Carrying Capacity ◽  
Squeeze Film ◽  
Load Carrying Capacity ◽  
Two Dimensional ◽  
Working Mechanism ◽  
Content Type ◽  
Patterned Surface ◽  
Load Carrying ◽  
Film Lubrication

Purpose This paper aims to investigate the squeeze film lubrication properties of hexagonal patterned surface inspired by the epidermis structure of tree frog’s toe pad and numerically explore the working mechanism of hexagonal micropillar during the acquisition process of high adhesive and friction for wet contacts. Design/methodology/approach A two-dimensional elastohydrodynamic numerical model is employed for the squeezing contacts. The pressure distribution, load carrying capacity and liquid flow rate of the squeeze film are obtained through a simultaneous solution of the two-dimensional Reynolds equation and elasticity deformation equations. Findings Higher pressure is found to be longitudinally distributed across individual hexagonal pillar, with pressure peak emerging at the center of hexagonal pillar. Expanding the area density and shrinking the channel depth or initial film thickness will improve the magnitude of squeezing pressure. Relatively lower pressure is generated inside interconnected channels, which reduces the load carrying capacity of the squeeze film. Meanwhile, the introduction of microchannel is revealed to downscale the total mass flow rate of squeezing contacts. Originality/value This paper provides a good proof for the working mechanism of surface microstructures during the acquisition process of high adhesive and friction for wet contacts.

Influence of water contamination in gear lubricants on wear and micro-pitting performance of case carburized gears

2017 ◽  
Vol 69 (4) ◽  
pp. 612-619 ◽  
Author(s):  
Christian Engelhardt ◽  
Jochen Witzig ◽  
Thomas Tobie ◽  
Karsten Stahl
Keyword(s):  
Carrying Capacity ◽  
Research Work ◽  
Load Carrying Capacity ◽  
Wear Performance ◽  
Content Type ◽  
Effect Of Water ◽  
Base Oils ◽  
Load Carrying ◽  
Different Types ◽  
Influence Of Water

Purpose Water can alter the performance of modern gear lubricants by influencing the flank load carrying capacity of gears significantly. The purpose of this paper is to investigate the influence of water contaminations in different kinds of base oils on the micro-pitting and wear performance of case carburized gears. Design/methodology/approach Concerning micro-pitting and wear, tests, based mostly on the following standardized tests, are performed on a Forschungsstelle fuer zahnraeder und getriebebau (FZG)-back-to-back gear test rig: micro-pitting short test Graufleckenkurztest (GFKT) according to DGMK 575 (screening test), micro-pitting test Graufleckentest (GT) according to FVA 54/7 (load stage test and endurance test) and Slow-speed wear test according to DGMK 377. To investigate the effect of water on the gear load carrying capacity dependent on different types of base oils, two polyglycol oils (PG1 and PG2), a polyalphaolefin oil, a mineral oil and an ester oil E are used. Each of these oils are common wind turbine gear oils with a viscosity ISO VG-220. Additionally, a manual transmission fluid with a viscosity of society of automotive engineers (SAE) 75W-85 is tested. Findings Considering the micro-pitting and wear performance, a significant decrease caused by water contaminations could not be detected. Regarding pitting damages, a generally negative influence was observed. This influence was differently distinctive for different base oil types. Especially non-polar lubricants seem to be affected negatively. The documented damages of the tooth flanks confirm this observation. While typical pitting damages appeared in test runs with polar lubricants, the disruption in test runs with non-polar lubricants was more extensive. Based on the experimental investigations, a general model of the damaging mechanisms of water contaminations in lubricants was derived. It is split into three partitions: interaction lubricant–water (effect of water on the molecular structure of base oils and additives), chemical-material-technological (especially corrosive reactions) and tribological influence (effect of water droplets in the contact zone). It has to be considered that the additive package of lubricants affects the influence of water contaminations on the flank load carrying capacity distinctively. An influence of water on the micro-pitting and wear performance in other than the given lubricants cannot be excluded. Originality/value While former research work was focused more on the effects of water in mineral oils, investigations concerning different types of base oils as well as different types of damages were carried out within this research project.

EXPERIMENTAL INVESTIGATION OF CFRP STRENGTHENED I-SHAPED COLD FORMED STEEL BEAMS

2017 ◽  
Vol 79 (5) ◽  
Author(s):  
Nahushananda Chakravarthy ◽  
Sivakumar Naganathan ◽  
Jonathan Tan Hsien Aun ◽  
Sreedhar Kalavagunta ◽  
Kamal Nasharuddin Mustapha ◽  
...  
Keyword(s):  
Carrying Capacity ◽  
Experimental Results ◽  
Steel Beams ◽  
Load Carrying Capacity ◽  
Load Carrying ◽  
Length Width ◽  
Cold Formed Steel ◽  
Formed Channel ◽  
Hot Rolled ◽  
Hot Rolled Steel

Cold formed steel differ from hot rolled steel by its lesser thickness and weight. The cold formed steel applicable in roof purlin, pipe racks and wall panels etc. Due its lesser wall thickness the cold formed steel member subjected to buckling. The enhancement of load carrying capacity of the cold formed steel member can be achieved by external strengthening of CFRP. In this study cold formed channel members connected back to back to form I shaped cross section using screws. These built up beam members were 300mm, 400mm and 500mm in length with 100mm screw spacing and edge distance of 50mm were chosen for testing. CFRP fabric cut according to length, width of built up beams and wrapped outer surface of beam using epoxy resin. Experiments were carried out in two sets firstly plain built up beams and secondly CFRP wrapped beams. The test results shows that increased load carrying capacity and reduction in deflection due to CFRP strengthening. Experimental results were compared with AISI standards which are in good agreement. Experimental results shows that CFRP strengthening is economic and reliable.

A study into the ability of SPD to restore the buckling strength and modes of rib stiffened panels with simulated stress corrosion cracks

2017 ◽  
Vol 8 (1) ◽  
pp. 63-78 ◽  
Author(s):  
Rhys Jones ◽  
Neil Matthews ◽  
Daren Peng ◽  
Nicholas Orchowski
Keyword(s):  
Experimental Study ◽  
Stress Corrosion ◽  
Carrying Capacity ◽  
Particle Deposition ◽  
Load Carrying Capacity ◽  
Load Path ◽  
Premature Failure ◽  
Content Type ◽  
Buckling Strength ◽  
Load Carrying

Purpose The purpose of this paper is to describe the results of a combined numerical and experimental study into the ability of supersonic particle deposition (SPD) to restore the load carrying capacity of rib stiffened wing planks with simulated stress corrosion cracking (SCC). Design/methodology/approach In this context the experimental results reveal that SCC can result in a dramatic reduction in the load carrying capacity of the structure and catastrophic failure via cracking that tears the length of the structure through buckling. A combined numerical and experimental study then reveals how this reduction, in the load carrying capacity can be overcome by using SPD. Findings This paper is the first to show that SPD can be used to restore the load carrying capacity of rib stiffened structures with SCC. It also shows that SPD repairs can be designed to have only a minimal effect on the local stiffness and hence on the load path. However, care should be taken to ensure that the design is such that premature failure of the SPD does not occur. Originality/value This is the first paper to show that a thin layer of SPD deposited 7,075 aluminium alloy powder on either side of the SCC-simulated stiffener has the potential to restore the load carrying capability of a rib stiffened structure. As such it represents an important first step into establishing the potential for SPD to restore the buckling strength of rib stiffened wing panels containing SCC.

Influence of hard rolling and the cooling lubricant on the material properties and the rolling strength of PM gears

2019 ◽  
Vol 71 (3) ◽  
pp. 406-410
Author(s):  
Fritz Klocke ◽  
Thomas Bergs ◽  
Christoph Löpenhaus ◽  
Philipp Scholzen ◽  
Tim Frech
Keyword(s):  
Boundary Layer ◽  
Carrying Capacity ◽  
Material Properties ◽  
Rolling Process ◽  
Surface Zone ◽  
Load Carrying Capacity ◽  
Content Type ◽  
Load Carrying ◽  
Phosphorous Content ◽  
Cooling Lubricant

Purpose The lower density of powder metallurgical (PM) gears compared to solid steel gears leads to not only a lower weight but also a lower load-carrying capacity. Therefore, PM gears are cold rolled before hardening to increase the density in the highly stressed surface zone and, thus, the flank load-carrying capacity. A further approach to increase the flank load-carrying capacity is the reduction of friction and wear in the tooth contact. The purpose of this paper is to analyze the hard rolling process as a new manufacturing step in the PM process chain to influence the boundary layer. Design/methodology/approach The investigation includes the new process of hard rolling, the variation of the cooling lubricant in the hard rolling process and the evaluation of its influence on the material properties and the flank load-carrying capacity. Therefore, the additives of the cooling lubricant are varied regarding the sulfur and phosphorous content. The load-carrying capacity is evaluated on disk-on-disk test rig and the material properties are evaluated by metallographic tests and boundary layer. Findings The results of the specimen characteristics in the micro and nano range show a significant influence of hard rolling on the residual stresses and the chemical surface composition. Because of hard rolling, residual compressive stresses as well as roughness are reduced and the flank load-carrying capacity is increased by high phosphorous content of the cooling lubricant. Originality/value This paper investigates a new manufacturing step to increase resource efficiency by increasing the flank load-carrying capacity of spur gears.

Analysis of misaligned water-lubricated polymer bearing with axial grooves

2019 ◽  
Vol 71 (3) ◽  
pp. 411-419 ◽  
Author(s):  
Fangrui Lv ◽  
Chunxiao Jiao ◽  
Donglin Zou ◽  
Na Ta ◽  
Zhu-shi Rao
Keyword(s):  
Carrying Capacity ◽  
Hydrodynamic Pressure ◽  
Maximum Pressure ◽  
Load Carrying Capacity ◽  
Misalignment Angle ◽  
Content Type ◽  
Load Carrying ◽  
Polymer Bearing ◽  
Journal Misalignment ◽  
Practical Implications

Purpose The purpose of this paper is to analyze the lubrication behavior of misaligned water-lubricated polymer bearings with axial grooves. Design/methodology/approach A lubrication model considering journal misalignment, bush deformation and grooves is established. In dynamic analyses of shaft systems, bearings are usually simplified as supporting points. Thus, an approach for solving the equivalent supporting point location is presented. The influence of misalignment angle and groove number on film thickness, hydrodynamic pressure distribution, load-carrying capacity and ESP location is investigated. Findings As the misalignment angle increases, the location of the maximum pressure and ESP are shifted toward the down-warping end, and the load-carrying capacity of the bearing decreases. In comparison to the nine-groove bearing, the six grooves bearing has a higher load-carrying capacity and the ESP is located closer to the down-warping end for an equivalent misalignment angle. Practical implications The results of this study can be applied to marine propeller shaft systems and other systems with misaligned bearings. Originality/value A study on the lubrication behavior of misaligned water-lubricated polymer bearings with axial grooves is of significant interest to the research community.

Influence of tribofilms on failures and friction of gears with particular focus on running-in

2019 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Andreas Ziegltrum ◽  
Stefan Emrich ◽  
Thomas Lohner ◽  
Klaus Michaelis ◽  
Alexander Brodyanski ◽  
...  
Keyword(s):  
Surface Analysis ◽  
Carrying Capacity ◽  
Experimental Investigations ◽  
Spur Gears ◽  
Load Carrying Capacity ◽  
Friction Behavior ◽  
Content Type ◽  
Load Carrying ◽  
Gear Contact ◽  
Local Pressures

Purpose This paper aims to address the influence of tribofilms and running-in on failures and friction of gears. The operation regime of gears is increasingly shifted to mixed and boundary lubrication, where high local pressures and temperatures occur at solid interactions in the gear contact. This results in strong tribofilm formation due to interactions of lubricant and its additives with the gear flanks and is related to changes of surface topography especially pronounced during running-in. Design/methodology/approach Experiments at a twin-disk and gear test rig were combined with chemical, structural and mechanical tribofilm characterization by surface analysis. Pitting lifetime, scuffing load carrying capacity and friction of ground spur gears were investigated for a mineral oil with different additives. Findings Experimental investigations showed a superordinate influence of tribofilms over surface roughness changes on damage and friction behavior of gears. Surface analysis of tribofilms provides explanatory approaches for friction behavior and load carrying capacity. A recommendation for the running-in of spur gears was derived. Originality/value Experimental methods and modern surface analysis were combined to study the influence of running-in and tribofilms on different failures and friction of spur gears.

Geometric Imperfection Sensitivity and Effect of Constraint Conditions of H-Section Columns under Compression

2010 ◽  
Vol 102-104 ◽  
pp. 140-144
Author(s):  
Yi Ping Wang ◽  
Yong Zang ◽  
Di Ping Wu
Keyword(s):  
Carrying Capacity ◽  
Steel Structures ◽  
Load Carrying Capacity ◽  
Imperfection Sensitivity ◽  
Geometric Imperfection ◽  
Manufacture Process ◽  
Buckling Behavior ◽  
Load Carrying ◽  
Thin Walled ◽  
Tolerance Control

The buckling behavior of thin-walled steel structures under load is still imperfectly understood, in spite of much research over the past 50 years. In this paper, the buckling behaviors of H-section columns under compression have been simulated with ANSYS. In the analysis, contact pairs between column ends and end blocks have been introduced into the model, and the load carrying capacity of the columns with four kinds of end constraint conditions and various typical initial geometric imperfections has been calculated and discussed. The results indicate that the load carrying capacity is most sensitive to the flexural imperfection, and the constraint condition cannot change the imperfection sensitivity of a column under compression, but improving restrain condition can heighten the load carrying capacity. They are helpful to the use and the tolerance control in the manufacture process of thin-walled H-section steel structures.

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