Flexural Behavior Research Articles

Enhancing the flexural behavior of GFRP single‐lap co‐cure joints reinforced with multi‐reinforcements

AbstractThe investigation focused on the glass fiber‐reinforced polymer (GFRP) composite co‐cure single lap joint (CC‐SLJ) that incorporates graphene nanoparticles (GNP) in epoxy and carbon fiber‐reinforced polymer (CFRP) Z‐pin reinforcement. The flexural test indicated that the integration of GNP and CFRP‐Z‐pin within the inner and outer layers of SLJ leads to improvement in flexural strength. The flexural strength of CC‐SLJ reinforced with GNP/epoxy and Z‐pin reinforcement reaches 145.02 MPa under static loading, with an improvement of 69.55% over the unreinforced SLJ. The SLJ under static loading with GNP/epoxy and graphene incorporated Z‐pin reinforced with demonstrate a significant improvement in flexural strength of 150.34 MPa, with an improvement of 71.22% over the unreinforced SLJ. Fractography revealed that the incorporation of GNP and Z pins into the SLJ enhances interfacial bonding between the adhesive and adherend, increases surface roughness, improves pin pull‐out resistance, and influences crack formation.Highlights The co‐cure technique is used to fabricate single‐lap GFRP composite joints. Carbon fiber‐reinforced polymer Z‐pin reinforced with GNP/epoxy adhesive. SLJ flexural strength was higher in 1.25 wt% of GNP and 2.5 vol% 90°/Z‐pin. Multiple reinforcements used in SLJ to achieve its maximum flexural strength. Failure analysis was conducted using microscopes and FESEM images.

Secondary bonded and co‐bonded CFRP composite joints with innovative lamination technique: Flexural and failure analysis

AbstractAdhesively bonded techniques effectively fuse the structural components in an assembly in aerospace applications. The co‐bonding is more effective than secondary bonding for joining fuselage frames to skins, wing ribs, and spars to skin joints. The flexural behavior and failure analysis of a carbon fiber‐reinforced polymer composite single‐lap joint is one crucial factor in aerospace applications. This research involved the fabrication of co‐bonded carbon fiber‐reinforced polymer composite single‐lap joints utilizing the vacuum bag hand lay‐up method, incorporating geometric modification techniques, including interleaved and covered lamination. The flexural strength was examined through a three‐point bending test. The results indicate that the secondary bonded with covered lamination techniques has attained the maximum flexural strength compared to others. The values are 80% higher than the neat secondary bonded joints. Moreover, the carbon fiber‐reinforced polymer composite single lap joint samples were examined for failure analysis using the ASTM D5573 standard. Furthermore, these geometric modifications in CFRP composite joints confirmed the significant enhancement in experimental results with less than 5% error rates.Highlights Carbon fiber‐reinforced polymeric (CFRP) joints were made utilizing interleaved and covered lamination methods. SB and CB methods were utilized to fabricate the CFRP composite joints. CL‐SBT exhibits high flexural strength (639 MPa) and modulus (45.94 GPa). A thin‐layer cohesive failure was observed in interleaved CFRP joints, The fiber tear failure was observed in covered lamination CFRP joints.

Numerical analysis of flexural behavior of sandwich beams using the FGM approach

Analytical modeling to predict the flexural behavior of sandwich beams using a triangular finite element model, the Triangular Plate Finite Element with Airy Function (TPAF). The originality of this model lies in the use of the deformation approach, which comprises three nodes and three degrees of freedom per node (one translation Wi and two rotations θxi and θyi). The main aim of this work is to validate the model by comparison with other solutions, in particular by means of an analytical prediction based on layer theory and the results obtained using CSB software. The originality of this study lies in the fact that the mechanical properties vary according to an exponential function along the height of the FGM section and remain constant in the other parts of the different composite sections. Tabular and graphical results are presented to illustrate the impact of deffrents, such as geometric factors (thickness configurations and length/thickness ratios), as well as boundary conditions and loads, on the static behavior of the beam.

Experimental study on the flexural behavior of ferrocement slab panels with supplementary cementitious silica fume and fiber materials

Ferrocement is a composite construction material with slender sections or panels, a rich cementitious mortar, and steel wire mesh as its principal reinforcing agent. The mortar matrix is designed to achieve optimal strength, density, impermeability, and workability, minimizing void formation and preventing map cracking. A study evaluated the workability and flexural strength of mortars prepared using three types of fine aggregates: Badarpur sand, Yamuna River sand, and Kilned Brick Powder. The mortar classifications included conventional mortar compositions (MCS), mortars with flyash and Silica Fume (MFSS), and mortars with flyash, silica fume, and human hair (MFSHS). The results showed that mixes incorporating these materials significantly improved workability, with MFSS-2 (Portland cement, Yamuna sand, plus 10% FA and 6% SF) showing the highest increase (42.50%). The high-strength formulations with supplementary materials were superior in terms of stiffness and structural integrity, with MFSHS-1 (Portland cement, Badarpur sand, 10% FA, 6% SF, and 1% HH fiber) showing the least deflection for any given load. The addition of 1% human hair fibers in the mortar matrix improved flexural strength in panels, acting as micro-reinforcements, enhancing the tensile strength alongwith mortar ductility.

A Numerical and Theoretical Investigation of the Flexural Behavior of Steel–Ultra-High-Performance Concrete Composite Slabs

A Numerical and Theoretical Investigation of the Flexural Behavior of Steel–Ultra-High-Performance Concrete Composite Slabs

Flexural behaviour of recycled ceramic aggregate concrete-filled double skin round steel tubes

Flexural behaviour of recycled ceramic aggregate concrete-filled double skin round steel tubes

Flexural behaviour of reinforced concrete beams strengthened with ultra-high ductility MPC-based composites

Flexural behaviour of reinforced concrete beams strengthened with ultra-high ductility MPC-based composites

Data Driven Framework with Graphical User Interface for Predicting Flexural Behavior of FRCM Strengthened RC Beams

In this study, the flexural capacity of reinforced concrete (RC) beams strengthened with fiber-reinforced cementitious matrices (FRCM) was computed using machine learning (ML) algorithms including: (i) adaptive neuro-fuzzy inference system (ANFIS), (ii) artificial neural network (ANN), and (iii) extreme gradient boosting (XGBoost). A total of 198 pertinent experimental datasets were compiled and included six types of FRCM composites (PBO, carbon, glass, basalt, coated carbon, and combined glass and carbon). The considered input parameters comprise the beam cross-sectional details, area of tensile and compressive steel reinforcement, mechanical properties of FRCM composite, and concrete compressive strength. To assess the reliability of ML models, four existing analytical models and one established standard guideline were used for comparison. Moreover, six statistical metrics were employed, along with an overfitting analysis, to determine the best-fitting model. Graphical fitting of the optimal model was depicted using the Taylor diagram, violin plot, as well as multi-panel histogram plot. Based on both graphical and statistical metrics, the XGBoost model attained the highest precision compared to all analytical and ML-based models. The correlation coefficient and MAPE of the XGBoost model were 0.9977 and 2.98%, respectively. To interpret the influence of individual parameters on the flexural strength of the FRCM-strengthened RC beams, a feature importance plot based on SHAP explanatory theory was deployed. Ultimately, a user-friendly graphical interface was developed and made accessible to aid practicing engineers in estimating the flexural strength of FRCM-strengthened RC beams, offering an effective alternative to complex design procedures.

Structural Performance of Reinforced Concrete Beams with Steel Fibres as Secondary Reinforcement: Experimental and Pre-peak Numerical Modelling

This research consists of an experimental and a numerical investigation into improving the structural performance of reinforced concrete (RC) beams by incorporating hooked-end steel fibres. Experimentally, steel fibres were added to the concrete matrix of 80 mm × 180 mm × 1500 mm RC beams with fibre contents of 0%, 0.5%, and 1%, without replacing traditional reinforcement bars. Each beam underwent a four-point flexural test using a hydraulic press under static loading to evaluate the influence of fibres on flexural behaviour. The numerical analysis aimed to model the macro-scale flexural behaviour of RC beams using a 3D finite element approach in ABAQUS. Challenges in modelling steel fibres include their discrete nature and computational demands due to intricate meshing and convergence issues. The Simplified Concrete Damaged Plasticity Model was used to characterize the compressive and tensile behaviours of plain and steel fibre reinforced concretes. Nonlinear finite element analysis was performed to predict pre-peak load versus mid-span deflection and crack propagation. The model, which does not explicitly simulate steel fibres, was validated against experimental data, showing strong agreement and confirming its effectiveness in capturing the flexural behaviour of steel fibre reinforced concrete beams. Experiments Results showed that steel fibres enhance the flexural performance. Beams with steel fibres exhibited higher first crack loads, ultimate loads, flexural strengths, and toughness. Additionally, the fibres increased crack numbers, reduced crack spacing and length, and improved post-cracking behaviour. The simulation results were subsequently validated against experimental data. The results of the numerical finite element analysis were in good agreement with those of the experiments.

Feasibility study of scapula bone as a next-generation material for biomedical applications

ABSTRACT This study investigates the influence of material thickness on the mechanical properties, specifically flexural and tensile properties, of scapula bone specimens from Deccani breed sheep in India. A three-point bending test and a tensile test were conducted on samples with varying thicknesses (1, 2 and 5 mm), and the flexural strength, flexural modulus, ultimate load, tensile deformation and von Mises stress were measured. Thicker specimens exhibited higher flexural properties than thinner counterparts. Statistical analysis using one-way ANOVA confirmed that material thickness significantly impacted the flexural and tensile properties of the samples. Additionally, a simulation analysis was performed using ANSYS Workbench to validate the experimental results and provide insights into the tensile and flexural behaviour of the specimens. The findings suggest that thicker samples are better equipped to handle bending stresses and tensile loads and are more suitable for applications requiring resistance to bending loads, stiffness, load-bearing capacity and tensile strength.

Cleavable Bio-Based Epoxy Matrix for More Eco-Sustainable Thermoset Composite Components.

Cleavable bio-based epoxy resin systems are emerging, eco-friendly, and promising alternatives to the common thermoset ones, providing quite comparable thermo-mechanical properties while enabling a circular and green end-of-life scenario of the composite materials. In addition to being designed to incorporate a bio-based resin greener than the conventional fully fossil-based epoxies, these formulations involve cleaving hardeners that enable, under mild thermo-chemical conditions, the total recycling of the composite material through the recovery of the fiber and matrix as a thermoplastic. This research addressed the characterization, processability, and recyclability of a new commercial cleavable bio-resin formulation (designed by the R-Concept company) that can be used in the fabrication of fully recyclable polymer composites. The resin was first studied to investigate the influence of the different post-curing regimes (room temperature, 100 °C, and 140 °C) on its thermal stability and glass transition temperature. According to the results obtained, the non-post-cured resin displayed the highest Tg (i.e., 76.6 °C). The same post-curing treatments were also probed on the composite laminates (glass and carbon) produced via a lab-scale vacuum-assisted resin transfer molding system, evaluating flexural behavior, microstructure, and dynamic-mechanical characteristics. The post-curing at 100 °C would enhance the crosslinking of polymer chains, improving the mechanical strength of composites. With respect to the non-post-cured laminates, the flexural strength improved by 3% and 12% in carbon and glass-based composites, respectively. The post-curing at 140 °C was instead detrimental to the mechanical performance. Finally, on the laminates produced, a chemical recycling procedure was implemented, demonstrating the feasibility of recovering both thermoplastic-based resin and fibers.

Theoretical model to predict the flexural response of concrete beams pre-tensioned with CFRP rods considering CFRP slippage effects

The overwhelming costs of maintenance for reinforced concrete structures due to steel corrosion have motivated researchers to look for alternatives. One of the promising alternatives is Fiber Reinforced Polymer (FRP). Among FRP materials, Carbon FRP (CFRP) is the most attractive material for prestressed concrete members due to its high tensile strength and modulus of elasticity. Previous studies investigated the use of CFRP in prestressed concrete through experimental tests and theoretical analysis. However, there is a significant need for more experimental data to develop an accurate model that can accurately predict the behavior of CFRP prestressed concrete beams. In the current study, experimental flexural tests were conducted on four prestressed concrete beams pre-tensioned with CFRP rods. The length of the beams was 4,270 mm, and the cross-sectional dimensions were 138 x 250 mm. All the beams were subjected to four-point loading with an initial five cycles of loading and unloading before a monotonic loading until failure. Their performance was analyzed, and based on the results a theoretical model was proposed. It was found that the slippage of CFRP at the ends significantly affect the flexural behavior and failure modes of the beams. Additionally, theoretical models must account for CFRP slippage at the ends to accurately predict the flexural response of CFRP prestressed concrete beams. When a slippage reduction factor was used in the proposed theoretical model, the results had a good agreement with the experimental tests. Future research may focus on testing the theoretical model with more data from experimental studies.

Experimental analysis of polymer-composite coated steel components under quasi-static loading

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. There aren’t any background studies looking into the failures of these thick coated structures and this study is attempting to bridge the gap in research by studying the monotonic flexural behaviour of these structures to investigate the reasons for its failures. The objective is to study the monotonic flexural behaviour of three popular particulate composite materials used as coatings on megayacht vessels and obtain an initial understanding of their behaviour and interaction with the steel substrate. The methods presented are both analytical and standard testing procedures for the examination of the flexural stress-strain response of the thick polymer-composite coated steel specimens. The results of this work suggest that different failure mechanisms have been observed in the three examined coating systems. It has been shown that the experimental data suggested no significant interaction between the steel and the polymer-composite material. The findings suggest that it is possible to enlarge the design space of the polymer-composite coatings by reducing the applied thickness of the materials. Results also have shown that the presence of voids cause reduction in strength by 20% and reduction in deformation by 30%. The study concluded to a two-step methodology involving analytical and experimental methods investigating the mechanical response of composite polymers applied on hull and superstructure substrates which is presented for the first time in this paper.

Flexural behavior of 3D Panel slabs under uniformly distributed gravity loads

After each major earthquake light weight structures that can be constructed in a short time period are needed to accommodate homeless people affect by the earthquake. 3D panel structures are one type of theses structures. The 3D panel is made of a 3 mm diameter steel wire space truss integrated with a polystyrene core sheet and it is converted to a structural wall after shotcreting it with concrete or cement mortar. In practice the 3D panels are used to construct one or two storey houses. In construction practice additional steel reinforcements are added to the 3D panels to construct roof or floor slabs. In this paper 3D panel slabs with steel reinforcements are tested under distributed gravity loads. Test results show that the steel reinforced 3D panels are able to withstand safely gravity loads specified by international codes, and mid span deflection values were less than the limits specified by international standards. Furthermore the 3D panel slabs show almost full composite behavior under flexural moment effects.

Multiscale modeling of multiwalled carbon nanotube‐reinforced polymer matrix nanocomposites and experimental validation

AbstractThis study developed a numerical model of multi‐walled carbon nanotube (MWCNT)‐reinforced polymer nanocomposite to predict the tensile and flexural behavior of an earth‐stationed antenna reflector. The objectives of the study were to propose a hierarchical model of nanocomposites and introduce the variability in the dimensions of the CNTs. The CNTs were meshed with beam elements and their inner, outer diameter, and length were randomized, as per field emission scanning electron microscopy image. The distribution of the CNTs was realized with the help of a random sequential adsorption algorithm. The CNT content was varied from 0.1 to 0.4 wt% of epoxy matrix. Periodic boundary conditions were implemented. Micro‐scale results were found to lie within 10% of the Halpin‐Tsai model. A concept of dynamically allocated representative volume element was implemented at the meso‐scale, which was then upscaled to macro‐scale to simulate ASTM D3039 and D790 test conditions. With 0.4 wt% of CNT into the matrix, the tensile and flexural modulus increased by 14.42% and 23.94%. The macro‐scale simulated results were compared with literature, where the tensile and flexural modulus were found to deviate by 7.5% and 3%. This model will later be upgraded with continuous fibrous reinforcement along with MWCNT‐filled epoxy, to simulate the performance of a real composite antenna reflector.Highlights Multiscale modeling of MWCNT‐based epoxy nanocomposite was developed. MWCNT was meshed with hollow beam elements as per FESEM images. 0.4 wt% MWCNT enhanced tensile and flexural modulus by 14% and 24%. Numerical tensile and flexural modulus lied within 7.5% and 3% of the tests.

Test and Theoretical Investigations on Flexural Behavior of High‐Performance H‐Shaped Steel Beam with Local Corrosion in Pure Bending Zone

This article undertakes the tested and theoretical investigations on the flexural behaviors of high‐performance steel (HPS) beams subjected to local corrosion in pure bending zone. Four H‐type HPS beams are designed, then the flexural bearing capacity test is carried out. Mechanical behaviors, including load‐deflection response, strain development, and failure modes are investigated in detail. A simple theoretical model of flexural strength is proposed. The tested and theoretical results show that: with the increase of corrosion rate, the random distribution of the residual section of HPS beam tends to be stable, the corrosion position also plays an important role in the random distribution of the residual area. The corrosion position has a greater influence on the residual flexural strength of corroded HPS beam than the corrosion degree. The theoretical flexural strength model can slight accurately predict the flexural strength of corroded H‐type HPS beam, the error is less than 5%. The corrosion of compressive flange has the most serious effect on the flexural strength degradation of HPS beams, followed by the corrosion of tensile flange and web corrosion. The influence of corrosion in the web height direction on the flexural strength of corroded HPS beam is extremely limited.

Finite Element Analysis of the Flexural Behavior of Steel Plate–High-Performance Concrete (HPC) Slab and Beam Composite Structures

This paper studied the flexural behavior of flat steel–HPC composite beams and corrugated steel–HPC composite slabs using finite element analysis. The accuracy and reliability of the finite element model were verified by comparing it with related experimental data in the literature. The influence of different factors on the flexural bearing capacity of the composite slab/beam is discussed. Increasing the concrete thickness, friction coefficient, concrete strength, and wave height of a corrugated steel plate and employing an optimized rebar configuration significantly enhanced the flexural behavior. Remarkably, increasing the thickness of the steel plate and the number of studs also improved the flexural bearing capacity, but an over-reinforcement phenomenon could easily occur, not being conducive to optimal structural performance. An equation for calculating the flexural bearing capacity of steel–HPC composite slab/beam structures considering the effects of the number of studs and the friction coefficient is proposed. The rationality of the proposed method was verified through the finite element results, providing a more accurate method for designing steel–HPC composite structures.

NUMERICAL INVESTIGATION ON FLEXURAL PERFORMANCE OF BUILT-UP STEEL BEAMS WITH DIFFERENT WEB OPENINGS

Recently, the usage of Structural Steel Beams with Opening in the Web has spread extensively in all over the world, in various types of buildings such as high-rise buildings and industrial buildings. There are several advantages in using openings in beams. There for, an analytical investigation was carried out on fourSteel Beams with Opening (SBWO) models by using a powerful nonlinear simulation software ABAQUS. The initiative was to study the overall flexural behaviour of (SBWO’s) and to establish the maximum load carrying capacity, and deflection. Only vertical loads have been considered in the (SBWO’s) performance investigation. The Built-Up sections were tested up to failure. The simulated models were considered to be under simply supported condition at their edges and a uniform distributed load were applied over the upper flange of the beam along all beam's length. The flexural behaviour of beams with different opening shapes were tested and compared. The test results proved to be very useful in selecting the opening shape.

Effects of Consolidation Parameters on Flexural Behavior of Polypropylene/Glass Fiber Thermoplastic Composites

In this study, the flexural behavior of glass fiber-reinforced polypropylene (GFR-PP) composites was systematically investigated under three-point bending conditions to evaluate the impact of key production parameters. Composite plates with a thickness of 4 mm were fabricated using a stepped mold under varying pressure levels (10, 20, and 30 bar) and durations under pressure (5, 10, and 20 minutes). The specimens were prepared according to ASTM standards to ensure consistency and reliability. The primary objective of this study was to understand how production parameters influence the mechanical properties of GFR-PP composites. The results indicated that the combination of low pressure (10 bar) and longer durations (20 minutes) led to superior flexural strength and enhanced fiber-matrix adhesion due to optimized consolidation, with a maximum flexural strength exceeding 500 MPa. In contrast, higher pressure levels (30 bar) resulted in fiber deformation and reduced mechanical performance. This work provides critical insights into the optimization of production parameters to achieve high-performance GFR-PP composites, with potential applications in aerospace and other lightweight structural components requiring high mechanical strength and durability.

Flexural behavior of UHPC-NC narrow steel box composite beam: Experimental and numerical investigation

Flexural behavior of UHPC-NC narrow steel box composite beam: Experimental and numerical investigation