Increase In Load Carrying Capacity Research Articles

Crossed helical gears—simulative studies and experimental results on non-involute geometries

Crossed helical gear units generally consist of a steel worm and a plastic helical gear with an axis crossing angle. Due to the high transmission ratio in a small installation space, they are used in auxiliary and actuating gears such as in window regulators, assembly lines, household appliances and positioning tasks. This paper deals with a calculation approach for crossed helical gears to include non-involute flank geometries for new and optimized gearboxes. The geometry derivation for general flank contours based on a polynomial and extends the geometric possibilities beyond the special case of the involute form. The use of principal curvatures and principal curvature directions to describe freely curved surface geometries enables the calculation of flank pressures, efficiency and sliding paths in the entire contact area. Previous studies confirmed the advantages in the mentioned load characteristics for geometries deviating from the involute. Furthermore, parameter studies show the influences of the individual design parameters and demonstrate the effects on operating behavior, with those a design recommendation for crossed helical gear units with general flank geometries can be created. ZC and ZC‑S geometries are used as calculation examples. With regard to the use of these new geometries in applications, manufacturing is a crucial aspect. Grinding disc parameters as well as a three-roll size to control the worm manufacturing for general flank geometries are necessary and described below. In addition to the theoretical calculation, a ZC crossed helical gear geometry was designed, manufactured and compared to a ZI reference gear in test rigs. This confirmed the advantages in load-carrying capacity and efficiency increase resulting from the calculation and proved the benefits.

Numerical analysis of hydromagnetic micropolar squeezing flow lubricated between porous elliptical plates

An attempt is made to analyze the effects of micropolar fluid squeezing film implementation between porous elliptical plates under the application of an external magnetic field. The appropriate improved hydromagnetic Reynolds equation governing the pressure distribution is acquired. The Reynolds equation is solved for lubrication features such as pressure distribution, load-carrying capacity and time-height relationships. It is noticed that a micropolar lubricant with a magnetic field may considerably impart a much-appreciated increase in load-carrying capacity, pressure distribution and response time compared to the classical case. Nevertheless, it is found that, as with the magnetic field, the larger values of the fluid gap number and the coupling number increase lubrication characteristics. Also, it is found that such a bearing cannot support a large number of lubrication characteristics because of the pores on the main path of fluid flow.

Fabrication and characterizations of glass fiber-reinforced functional leaf spring composites with or without microcapsule-based dicyclopentadiene as self-healing agent for automobile industrial applications: comparative analysis

This study described a critical review of the biological system of self-curing agents and catalysts in which damage triggers an automatic healing response. In the first phase, a glass fiber-reinforced composite (GFRC) mono-leaf spring was prepared, which is made of glass fiber with a cement-based metal matrix. GFRC was further embedded with a microcapsule-based self-healing agent dicyclopentadiene (DCPD) that prevents sudden breakdown/failure of automobile suspension components resulting in micro-cracks produced in the material due to constant load application. In this paper, GFRC mono leaf spring samples were prepared with and without a healing agent under three different categories of varying thicknesses 20, 30, and 40 mm. In the second phase, the load-carrying capacity of all the samples was investigated and found a continuous increase in load-carrying capacity. Percentage increase in load carrying capacity before the time break was 1.09%, 1.42%, and 1.08% followed by time break of 05 min was 24.24%, 17.67%, and 21.67% respectively. It was clearly identified from the results that the addition of microcapsule-based healing substituents increases the load-carrying capacity of GFRC mono-leaf spring and avoids sudden fracture.

Performance analysis of journal bearing having surface waviness operating under misaligned condition

In this present study, the effect of surface waviness on the performance of journal bearing operating in misaligned conditions has been investigated. The journal’s misaligned conditions in the present analysis are taken about the circumferential, the axial, and both axes. For computing the pressure of lubricant inside the bearing, the finite element method has been applied to solve the Reynolds equation and thus static parameters are obtained. The static parameters, that is, load carrying capacity and coefficient of friction are evaluated at different waviness variables and are compared with misaligned journal bearing without surface waviness. It is observed that misalignment considered in both axes has the most severe effect on static performance parameters as compared to misalignment only in the circumferential or axial axis. With the increase in circumferential waviness number up to n = 5, the load-carrying capacity increases, and the coefficient of friction decreases under high eccentricity ratios. Change in waviness amplitude also impacts the bearing performance. Axial waviness always deteriorates the bearing performance. Combined waviness increases the load carrying capacity and decreases the coefficient of friction when circumferential waviness number n = 5 and axial waviness number m = 2. The highest performance enhancement ratio is attained at an eccentricity ratio of 0.8 with a circumferential waviness number n of 5, axial waviness number m of 2, and dimensionless waviness amplitude [Formula: see text] of 0.075.

Numerical Analysis of a Dual-Layer Geosynthetic-Encased Stone Column Installed in Soft Soil

Stone columns are being used to reduce soft soil settlement and increase load-carrying capacity. Since there is inadequate lateral support from the local native soil, soft soil undergoes excessive settlement under vertical loading. This issue is effectively resolved by suitably encasing stone column material by geosynthetic with significant axial stiffness, which provides the required additional confinement reported in the literature. In the current study, an effort has been made to examine the load settlement behaviour of the dual-layered geosynthetic-encased stone column (DL-GESC) under vertical loading. In order to simulate the behaviour of stone column-reinforced soft soil, a FEM analysis was performed using PLAXIS-3D and three-dimensional (3D) models made utilising the unit cell idealisation technique for a single column. The stone column diameter, spacing to diameter (s/d) ratio, and encasement layers were varied to determine their influence on load-settling behaviour. The vertical load-carrying capacity of the ground was significantly improved when an additional layer of geosynthetic encasement was inserted into the stone column as compared to SL-GESC. Improvement of 15–25% was observed for the analysis of a single column installed in soft clay, according to the result obtained. Improvement ratios have been discussed in detail for various encasement conditions.

Seismic Upgradation of RC Beams Strengthened with Externally Bonded Spent Catalyst Based Ferrocement Laminates

Globally, since there are more systems of civil infrastructure, there are also more degraded buildings and structures. If upgrading or strengthening is a practical option, complete replacement is likely to be an escalating financial burden and may be a waste of natural resources. It is necessary to repair or strengthen a number of reinforced concrete buildings and structures in order to boost their load-bearing capabilities or improve their ductility under seismic stress. Additionally, due to changes in service circumstances, a structure might need to be modified to reduce deflections or manage cracking. Strengthening may be preferable to limiting usage, capping applied loads, and regularly inspecting the structure rather than removing the existing structure or part and building a new one. This study aims to examine the flexural, shear, and combined effect of flexural and shear behavior of reinforced concrete (RC) beams strengthened with externally bonded spent catalyst-based ferrocement laminates and compare them to the control beams (unstrengthened) under two-point loading conditions. This study involves researching laminates with various spent catalyst doses, such as 3, 6, 9, and 12%, in an effort to determine the best amounts that will improve the structural performance of ferrocement laminates. Twelve spent catalyst-based ferrocement laminates measuring 500(L) × 125(B) × 20 mm (thickness) with 3% volume fraction of meshes each were cast and tested in the lab as part of the preliminary investigation. For repeatability, three laminates per case were employed. Eight numbers of under-reinforced RC beams measuring 75(L) × 100(B) × 150(D) mm were cast for the main study; six numbers were strengthened with optimized spent catalyst-based ferrocement laminates bonded with flexible epoxy systems at the tension zone, shear zone, and combination of tension and shear zone. Two of the beams were cast as control specimens. The beams were then evaluated using a Universal Testing Machine (UTM) with a 1000 kN capacity under two-point loading conditions. As a result, the strength, yield load, ultimate load, stiffness, ductility, and related failure modes of all tested beams' flexural and shear performances were examined. According to a preliminary analysis of laminates made of spent catalyst, the dosage of 9% provides good flexural strength in comparison to other doses. In comparison to the strengthened beam, the control beam's initial cracks appeared earlier. In comparison to the control beam, the strengthened beam has an increase in load-carrying capacity of 18% for flexure, 16% for shear, and 30% for the combined impact of flexure and shear. In comparison to the control beam, the deflection of the strengthened beam was decreased by close to 20 to 40% for flexure, 10 to 30% for shear, and 15 to 20% for the combined effects of flexure and shear at the same load level. In relation to control beams, the ductility also improved up to 30% for flexure, 25% for shear, and 25% for the combined impact of flexure and shear. Similar to this, the retrofitted beam is stiffer than the control beam by approximately 40% for flexure, 48% for shear, and 30% for the combined effect of flexure and shear. Theoretical formulation by section analysis is also derived and it gives close agreement with control and strengthened beams. The flexural and shear strengthening of the RC beam retrofitting system is effectively increased by using spent catalyst-based ferrocement laminates. No beam showed signs of premature and brittle failure. According to the test findings, it can be said that spent catalyst-based ferrocement reinforced beams perform better in every way than control beams. Doi: 10.28991/HIJ-2023-04-01-013 Full Text: PDF

Experimental Investigation of Effect of L-Profile Hybrid Aluminium/GFRP to the Axial and Lateral Characteristic.

The current study investigates the effect of a hybrid L-profile aluminium/glass-fiber-reinforced polymer stacking sequence under axial and lateral compression loads. Four stacking sequences are studied: aluminium (A)-glass-fiber (GF)-AGF, GFA, GFAGF, and AGFA. In the axial compression test, the aluminium/GFRP hybrid tends to crush in a more progressive and stable failure than the net aluminium and net GFRP specimens, with a relatively more stable load-carrying capacity throughout the experimental tests. The AGF stacking sequence was second, with an energy absorption of 145.31 kJ, following AGFA at 157.19 kJ. The load-carrying capacity of AGFA was the highest, with an average peak crushing force of 24.59 kN. The second-highest peak crushing force, 14.94 kN, was achieved by GFAGF. The highest amount of energy absorption, 157.19 J, was achieved by the AGFA specimen. The lateral compression test showed a significant increase in load-carrying and energy absorption capacity in the aluminium/GFRP hybrid specimens compared to the net GFRP specimens. AGF had the highest energy absorption with 10.41 J, followed by AGFA with 9.49 J. AGF also had the highest peak crushing force with 2.98 kN, followed by AGFA with 2.16 kN. The most crashworthy stacking sequence among the four variations tested in this experimental research was the AGF stacking sequence because of its great load-carrying capacity, energy absorption, and specific energy absorption in axial and lateral loading. The study provides greater insight into the failure of hybrid composite laminates under lateral and axial compression.

Study of Application of Fiber Reinforced Concrete in Anchorage Zone

In the case of post-tensioned or geotechnical structures, the anchorage zone is considered a critical part of the design and construction process. Generally, the failure of the anchorage zone is one of the most common problems. High-bearing stresses create significant transverse tension. For these reasons, conventional reinforcement, usually in the form of closed stirrups, must be designed. The presented analysis is focused on the possible increase of load-carrying capacity of the anchorage zone with steel fiber-reinforced concrete. Three types of specimens were analyzed. The first type of specimen represented the anchorage zone made from standard reinforced concrete. The second and third series of specimens were designed from fiber-reinforced concrete with two different volumes of steel fibers added into the anchorage zone. The parameters used in the numerical analysis of the anchorage zone were experimentally determined on a set of beam specimens. In the analysis, the anchorage zone was loaded by a node force applied on a steel load distribution plate placed on the top edge of the bloc. The performed numerical study suggests that the load-bearing capacity can be increased by adding fiber-reinforced concrete with a higher volume of fiber (Dramix 3D 55/30, volume of fiber of 110 kg/m3) into the vicinity of the anchorage plate.

Influence of Haunch Geometry and Additional Steel Reinforcement on Load Carrying Capacity of Reinforced Concrete Box Culvert

The culverts are used to safely convey water under railways, highways, and overpasses. They are utilized in drainage areas or water channels and in areas where the bearing capacity of soil is low. The design and construction of this crucial infrastructure need to be improved to meet contemporary demands of reliability and affordability. Precast reinforced box culverts are popular alternatives as they ensure strength, durability, rigidity, and economy. This research seeks to develop an effective and affordable design improvement procedure for a precast box culvert using modern numerical tools. The Finite Element Method (FEM) based approach is used in studying the effects of haunch geometry and additional steel reinforcement on the load-bearing capacity of box culverts. A conventional box culvert is analyzed to create the numerical models in the Abaqus FEM code and to investigate the load-bearing capacity of culverts with an expanded span. The outcomes of the study reveal the critical places for stress concentration as well as the location of maximum damage. It is found that haunch geometry and additional reinforcement at these critical places significantly affect the load-carrying capacity of a culvert. From the comparison of capacity curves of models with and without haunches and diagonal reinforcement, it is found that a 25% increase in load-carrying capacity is achievable with the recommended changes. The proposed design improvement technique can be employed for the cost-effective and safe design of a concrete box culvert with larger span lengths and high water-flowing capacities. The findings of this study are expected to assist practitioners in strength enhancement tasks of box culverts for increased structural stability and drainage efficiency.

Flexural performance of high-strength lightweight concrete beams made with hybrid fibers

This paper reports on the flexural response of lightweight high strength concrete beams, (LWHSC) reinforced with different combinations of discrete, discontinuous and randomly distributed steel, crimped polypropylene and recycled plastic fibers. All the LWHSC beams tested failed in a typical flexural failure mode, in which flexural vertical cracks appeared within the constant moment zone. Analysis of the test results indicated that the fiber reinforced LWHSC beams exhibited significant increase in load carrying capacity, flexural toughness and ductility indices compared to control LWHSC beams without fibers. Among all the beams tested, the ones reinforced with 0.5% of 60 mm long steel fibers and 0.25% of crimped polypropylene fibers exhibited the largest increase, about 18% in load carrying capacity and flexural toughness compared to control beam specimens without fibers. While, the beams reinforced with 0.5% (50/50 blend) of short steel fibers (30 mm and 60 mm long), and 0.25% of recycled plastic fibers outperformed the flexural toughness of similar beams containing equal content of steel fibers and 0.25% of crimped polypropylene fibers by about 6%. Furthermore, test results indicated that an eco-friendly locally produced recycled plastic fibers could be successfully used for enhancing the flexural performance of LWC beams without compromising their load carrying capacity. Moreover, finite element software ABAQUS was used for predicting numerically the flexural response and crack progression of the beams investigated. The numerical predictions compare fairly well with the experimental test results

Experimental Investigation on the Axial Compressive Behaviour of Cold-Formed Steel-Concrete Composite Columns Infilled with Various Types of Fibre-Reinforced Concrete

The exceptional structural strength and low cost of steel-concrete composite columns make them a popular choice for civil engineering structures. Numerous forms of composite columns, including steel tubes filled with concrete, have been produced recently in response to various construction situations. Cold-formed steel tubular columns with concrete filling have higher strength and ductility due to their capacity to withstand inner buckling and postpone outward buckling. The objective of this research is to determine the ductile and strength performance of composite columns containing various forms of fibre-reinforced concrete when subjected to axial compression. Several different kinds of fibre-reinforced concrete (FRC) are employed as additives in hollow steel columns, including steel FRC, carbon FRC, glass FRC, coir FRC, jute FRC, and sisal FRC. Axial compression tests were performed on 24 columns, including three hollow steel columns and 21 composite columns. Three distinct slenderness ratios were developed and used. Axial bearing capacity, compressive stress-strain curves, ductility, peak strain, axial shortening, and toughness were among the topics covered by the axial compression test. Experimental findings demonstrated that all conventional composite columns experienced failure through overall buckling, Local buckling and crushing of concrete infill, which was transformed into more ductile failure using fibre-reinforced concrete infills. The test results revealed that fibre-reinforced concrete-infilled steel columns outperformed conventional composite columns in terms of strength, ductility, and energy absorption capacity. The percentage increase in load-carrying capacity was observed as 203.88%, 193.48% and 190.03% when compared to hollow cold-formed steel tubular columns in medium, short and stub columns, respectively. Under assessment of stub, short, and medium columns, the load-strain plots demonstrated that the steel fibre-reinforced concrete in-filled columns performed well in terms of ductility. Localized buckling and crushing of the concrete infill caused the composite columns with low slenderness ratios to fail. In contrast, concrete-filled steel tube columns with higher slenderness ratios showed column failure through the overall buckling of the composite column.

Behaviour of New Curved in Plan Composite Reinforced Concrete Beams

New composite reinforced concrete beams, in which reinforced concrete component is connected to steel T-section, are proposed. The stirrups of the beam were utilized as shear connectors by passing them through drilled holes in the web of the steel T-section. Experimental test and numerical analysis were conducted to determine the behaviour of such beams when subjected to combined shear, torsion, and bending stresses. Full scale one conventional reinforced concrete curved in plan beam C1, and four composite reinforced concrete ones, C2 to C5, were tested. The degree of shear connection between the two components of beams C2 to C5 was changed by varying the number of stirrups which are used as shear connectors. The increase in load carrying capacity of the composite reinforced concrete beams reached 55 % for beam C4 as compared to that of ordinary reinforced concrete beam. The experimental results demonstrated that the stirrups are very effective in providing the interaction between the two components of the beams. The degree of shear connection emerged not to have effect on the behaviour of tested beams. Three-dimensional finite element analysis was conducted using commercial software ABAQUS. To model the shear connection in composite reinforced concrete beam, the stirrups were connected to the web of the steel T-section by springs at the location of the stirrups. Good agreement is obtained between the results of the experimental tests and the finite element analysis.

Uplift Load Carrying Capacity of Cylindrical and Belled Pile in Cohesive soil Bed

Foundation of some structures like transmission towers, mooring systems for ocean surface or submerged platforms, tall chimneys, jetty structures etc. are subjected to uplift loads. Literature reflects that scholars have conducted pull out field prototype and model test and failure pattern of soil is studied for belled piles in loess soil and cohesionless soil. In this research work, the authors have carried out 36 tests on single pile and pile groups and uplift load carrying capacity is obtained by experimental investigation of single pile, triangular pattern (2x1) and square pattern (2x2) using the model piles of cylindrical and belled shaped in cohesive soil of soft consistency. The piles are having 20 mm shaft diameter and varying L/d ratio of 6, 8,10,15,18 and 20 for both cylindrical pile and belled pile. Belled portion is cast in belled pile with an angle of 70° with horizontal and having base diameter of 60 mm and height 55 mm. Spacing between two piles in various pile group was kept three times the piles shaft diameter (3d) in all experiments. Based on the experimental results as the L/d ratio increases uplift load carrying capacity increases. Uplift load carrying capacity of single pile, triangular pile group and square pile group of belled pile is 410%, 280% and 240% more than cylindrical piles. Uplift load carrying capacity of triangular pile group and square pile group increases by 182% and 273% for cylindrical pile and 104% and 141% for belled pile in comparison with single pile. Failure pattern of soil is obtained from experiments performed on belled pile and by using this failure pattern, theoretical uplift load carrying of belled pile is obtained.Uplift load carrying capacity.

Wear and Lubrication Performance of Different Reticular-Textured TiN-Coated Surfaces under Lubricated Conditions

Texture and coating technology can significantly improve the tribological properties of mechanical components. In this study, the lubricating and wear properties of the reticular surface texture under the action of TiN were studied. Lubrication and wear experiments at different speeds were conducted using a UMT-3 wear and friction testing machine. Using Fluent fluid simulation, the bearing capacity of the oil film was obtained, and the lubrication performance of the texture was verified. The results showed that the simulation experiment and the lubrication experiment were consistent to a certain extent. For the groove width and angle parameters studied in this paper, optimal parameters existed to achieve the maximum bearing capacity, 1.27 N. Due to the high hardness and low elastic modulus of the TiN coating, the coated reticular texture was more wear-resistant, and it achieved the minimum wear volume 1.148 × 10−6 mm3 from the grinding stainless-steel matrix. The effect of the fluid dynamic pressure, wear debris collection, and lubricating oil storage were the main reasons for the increase in load-carrying capacity and the decrease in wear with the coated reticular texture.

Static and Dynamic Behavior of Circularized Reinforced Concrete Columns Strengthened with Hybrid CFRP

In this study, three strengthening techniques, near-surface mounted NSM-CRFP, NSM-CFRP with externally bonding EB-CFRP, and hybrid CFRP with circularization were studied to increase the seismic performance of existing RC slender columns under lateral loads. Experimentally, 1:3 scale RC models were studied and subjected to both lateral static load and seismic excitation. In the dynamic test, a model was subjected to El Centro 1940 NS earthquake excitation by using a shaking table. According to the test results, the strengthening techniques showed a significant increase in load carrying capacity, of about 86.6%, and 46.6%, for circularization and NSM-CFRP respectively, of the reference unstrengthened columns. On the other hand, columns strengthened with hybrid NSM-CFRP and EB-CFRP showed a different failure mode. Dynamically, the lateral drift was decreased by about 75%, 47%, and 49% for earthquake amplitudes of 0.05g, 0.15g, and 0.32g respectively. Finally, it was concluded, depending on the static and dynamic analyses, that the circularization process showed a significant increase in lateral load-bearing capacity.

Flexural Behaviour of Lightweight Reinforced Concrete Beams Internally Reinforced with Welded Wire Mesh

Lightweight clay aggregate (LECA) is manufactured by heating clay with no lime content in the kiln; as a result, the water evaporates and angular clay balls with pore structures are obtained. LECA possess internal curing properties as any other lightweight aggregate due to their pore structure and higher water absorption capacity. In this work, experimental and analytical behaviour using LECA as a 100% replacement for coarse aggregate to make lightweight concrete (LWC) beams was studied. The LWC beams were compared to the conventional concrete beams in load-deflection, energy absorption capacity, and ductility index. Internal mesh reinforcement using welded wire mesh (WWM) of (4 layers of 15 mm square spacing, 4 layers of 10 mm square spacing, and 4 layers of 15 mm and 10 mm mesh placed alternatively) was provided to enhance the load-carrying capacity of the LWC beam without increasing the dimensions and self-weight of the beams. The beam internally reinforced with WWM exhibited higher load carrying capacity and withstood more significant deflection without sudden failure. The internal reinforcement of WWM is provided to make steel rebars, and WWM works monolithically while loading; this will reduce the stress on tension bars and increase load-carrying capacity. Finally, the generated analytical findings agreed well with the experimental data, demonstrating that the analytical model could mimic the behaviour of LWC beams with WWM.

Study on the influence of interfacial slip on the lubrication performance of a step slider bearing

Experimental and theoretical studies have been completed in this paper to investigate the interface effect in the lubrication performance of a step slider bearing. Oleophobic fluorine-containing diamond-like carbon (F-DLC) coatings were prepared on the step slider to provide low affinity to lubrication films. With an optical slider bearing test rig, it is revealed that the F-DLC coating presents an increase in the film thickness/load-carrying capacity and a decrease in the coefficient of friction (COF), which is quite different from the common idea that both the load-carrying capacity and the COF are reduced at the same time. Contact angles measurement on the step slider shows that the affinity to the lubricant of the inlet step surface is lower than that of the outlet land, which can be attributed to the rougher surface of the step surface by the laser ablation. Theoretical analyses show that various interfacial slip velocities on the inlet step and the outlet land can generate different change in the load-carrying capacity and the COF. When the step surface presents lower interfacial slip velocity of the film than the land surface, increase in load-carrying capacity and decrease in the COF can be theoretically found to support the experiments finds.

Double-Layered Porous Rayleigh Step Slider Bearings Lubricated with Couplestress Fluids

Objective: To examine the performance of double-layered porous Rayleigh step slider bearings lubricated with couple stress fluid and to compare it with the performance of single layered porous Rayleigh step bearing. Methods: Based on the Stokes micro continuum theory of couple stress fluids, the modified Reynolds equation governing fluid film pressure is derived. Its analytical solution is and the closed form expressions for the fluid film pressure, frictional force and load carrying capacity are obtained. Findings: The numerical results for bearing characteristics such as pressure, load carrying capacity, frictional force are plotted graphically to study the effect of doublelayered porous facing. The effect of permeability of the porous layer is to decrease the load carrying capacity as it gives an easy path for the lubricant to pass through. This adverse effect can be compensated by introducing double layered porous facing with different permeabilities and the results presented here in this paper clearly shows the increase in load carrying capacity and decrease in co-efficient of friction for the double layered porous bearings as compared to that of single layered porous bearings. Novelty: Original research was conducted on double-layered porous Rayleigh step slider bearings with couple stress fluid by considering the effects of lubricant additives in the porous region and the results are compared with that of single layered porous bearings. Keywords: Rayleighstep slider bearing; permeability; Doublelayered porous; couple stress fluid Microcontinuum

Flexural response of composite coated steel components using the extended finite element method

In recent years, there has been new interest in understanding the mechanical failures of the polymer-composites used for fairing the hull and the superstructure of large vessels. On average, around 200 superyachts are launched every year, with about 50% of them presenting failures in their polymer-composite coating schemes. Very little literature data is available in understanding the fracture response of these materials for this particular application. This paper presents a numerical study on the flexural behaviour of three popular particulate polymer-composite materials used as coatings on megayacht vessels using the extended finite element method in Abaqus®. The numerical results have been validated against experiments carried out by the authors and good correlation has been obtained.The use of the correct mechanical properties obtained from mechanical testing of the bulk materials, has yielded accurate predictions of the flexural characteristics of the composite-steel specimens up to failure. Three different coating systems have been evaluated with the methodology outlined in this paper. This study demonstrates that validation of the numerical methods with experimental results creates the opportunity for the development of more parametric studies with a reduced requirement to conduct physical tests.The numerical results correlate well with the experimental results carried out by Prodromou [1]. The failure loads were predicted with an accuracy of 20% maximum difference from experiments whereas the deformation was predicted within a range of 12% maximum difference from experimental values. (Differences in the failure analysis results could be attributed to the varying properties of the polymer test coupons, however, validation provides encouraging results). Parameters such as the effect of thickness and the differing properties of the polymer-composites have been discussed. It has been found that coated coupons of low thickness can perform better in terms of deflection, thus reducing the probability of failure in real application. The increase in coating thickness leads to an increase in load carrying capacity and flexural rigidity of the beam as expected. Increased thickness of coating could increase surface stresses hence lead to earlier occurrence of cracking. The modelling procedure captured with accuracy the failure response of the composite under quasi-static loading conditions.

Seismic retrofit of unreinforced masonry walls using precast panels of fiber-reinforced cementitious composite

In this study, a practical seismic retrofit technique was developed for unreinforced masonry (URM) walls using precast panels of fiber-reinforced cementitious composites (FRCC). A hybrid fiber-type comprising steel and nylon fibers with a total volume fraction of 1% was adopted for fabricating the FRCC panels. A total of five URM walls were fabricated and tested under cyclic loading. The primary test parameters are the shear key types between precast panels and steel reinforcement details for the precast panels. From the test results, the URM walls retrofitted by precast panels with the proposed shear keys and reinforcement details showed a great improvement in terms of load-carrying and deformation capacity, stiffness degradation, and energy dissipation capacity compared to the control URM specimen. In addition, test specimens using additional reinforcement such as steel re-bars in the grooves of the panels and turnbuckles exhibited an increase of load-carrying capacity in both loading directions, in comparison with the counterparts without additional reinforcement. Eventually, a strength model was proposed to estimate the lateral strength of URM walls retrofitted by precast panels, and overall, its prediction indicates a good correlation in comparison with the experiment results.