Bending Loads Research Articles

Whole-local mechanical analysis and application of long-distance oil and gas pipelines considering dents caused by loading

Dental defects are relatively common in long-distance pipeline engineering and can lead to permanent plastic deformation of the pipeline, compromising its structural integrity. To clarify the evolution process of the dented pipelines in engineering practice, this paper puts forward the method of combining the whole and local calculation to analyze the mechanical behavior of pipeline indentations. Based on the combination of whole and local method, the influence of concentration, bending and internal pressure load on the indentation deformation of long-distance oil and gas pipelines under typical scenarios is explored. The research found that the simulated values of indentation depth largely coincided with the measured values. The Mises stress, equivalent plastic strain, and indentation depth reached their maximum values at the contact edges between the pipeline and the supports, making the contact edge between the pipeline and the support the most unfavorable position. In the significance analysis of loads, it is found that the stress change of the pipeline was significant under concentrated loads. As the internal pressure gradually increased, the pipeline stress exhibited a trend of first decreasing and then increasing. When the internal pressure load is 4 MPa, the Mises stress reached its minimum value. During the service stage of the pipeline, low-load conditions can lead to the elastic recovery of indentation deformation in the pipeline, but high-load conditions will exacerbate the indentation deformation, which is detrimental to the continued service of the pipeline. In this study, the mechanical analysis of long-distance oil and gas pipeline is carried out by combining the whole and local, which provides a new technical idea and guarantee for the development of long-distance oil and gas pipeline mechanical analysis industry.

Strength and Stiffness of Corrugated Plates Subjected to Bending

When a beam twists, localized flexural deformation in the plate occurs at the connection between the corrugated plate and the beam, resulting in a reduction in the bracing stiffness of the corrugated plate. To accurately assess the bracing stiffness of a beam with a connected corrugated plate, it is essential to independently determine the bending stiffness of the corrugated plate and the rotational stiffness of the plate–beam joint. This study conducts bending experiments on corrugated plates subjected to in-plane bending to elucidate the stress mechanisms within the plates. The influence of the width-to-thickness ratio on the bending load and bending stiffness of the corrugated plates is examined using the width-to-thickness ratio regulations of various countries. The findings revealed that when the width-to-thickness ratio of the corrugated plates used in this study was lower than the threshold specified in the Eurocode, the bending load at the onset of stiffness degradation was approximately 80% of the maximum bending load, and the initial bending stiffness corresponded closely to the theoretical value. Conversely, when the web width-to-thickness ratio of the corrugated plates exceeded the limit prescribed in the Eurocode, it was demonstrated that the maximum bending load decreased to approximately 50% of the yield load, and the initial bending stiffness was reduced to about 95% of the theoretical value.

Sustainable surface coating strategy for the Interface compatibilization of hybrid high-density polyethylene microfibers and geopolymer-based composite: A versatile path for an efficient brittle to ductile-like transition

Sustainable surface coating strategy for the Interface compatibilization of hybrid high-density polyethylene microfibers and geopolymer-based composite: A versatile path for an efficient brittle to ductile-like transition

Seismic Performance Assessment of GFRP-RC Circular Columns under High Torsion Combined with Bending and Shear Cyclic Loading

Seismic Performance Assessment of GFRP-RC Circular Columns under High Torsion Combined with Bending and Shear Cyclic Loading

Prediction of vertebral failure under general loadings of compression, flexion, extension, and side-bending.

Bone pathologies such as osteoporosis and metastasis can significantly compromise the load-bearing capacity of the spinal column, increasing the risk of vertebral fractures, some of which may occur during routine physical activities. Currently, there is no clinical tool that accurately assesses the risk of vertebral fractures associated with these activities in osteoporotic and metastatic spines. In this paper, we develop and validate a quantitative computed tomography-based finite element analysis (QCT/FEA) method to predict vertebral fractures under general load conditions that simulate flexion, extension, and side-bending movements, reflecting the body's activities under various scenarios. Initially, QCT/FEA models of cadaveric spine cohorts were developed. The accuracy and verification of the methodology involved comparing the fracture force outcomes to those experimentally observed and measured under pure compression loading scenarios. The findings revealed a strong correlation between experimentally measured failure loads and those estimated computationally (R2=0.96, p<0.001). For the selected vertebral specimens, we examined the effects of four distinct boundary conditions that replicate flexion, extension, left side-bending, and right side-bending loads. The results showed that spine bending load conditions led to over a 62% reduction in failure force outcomes compared to pure compression loading conditions (p≤0.0143). The study also demonstrated asymmetrical strain distribution patterns when the loading condition shifted from pure compression to spine bending, resulting in larger strain values on one side of the bone and consequently reducing the failure load. The results of this study suggest that QCT/FEA can be effectively used to analyze various boundary conditions resembling real-world physical activities, providing a valuable tool for assessing vertebral fracture risks.

Probabilistic Modelling of Fatigue Behaviour of 51CrV4 Steel for Railway Parabolic Leaf Springs

The longevity of railway vehicles is an important factor in their mechanical and structural design. Fatigue is a major issue that affects the durability of railway components, and therefore, knowledge of the fatigue resistance characteristics of critical components, such as the leaf springs, must be extensively investigated. This research covers the fatigue resistance of chromium–vanadium alloy steel, usually designated as 51CrV4, from the high-cycle regime (HCF) (103–104) up to very high-cycle fatigue (VHCF) (109) under the bending loading conditions typical of leaf springs and under uniaxial tension/compression loading, respectively, for a stress ratio, Rσ, of −1. Different test frequencies were considered (23, 150, and 20,000 Hz) despite the material not exhibiting a relatively significant frequency effect. In order to create a new fatigue prediction model, two prediction models, the Basquin SN linear regression model and the Castillo–Fernandez–Cantelli (CFC) model, were evaluated. According to the analysis carried out, the CFC model provided a better prediction of the fatigue failures than the SN model, especially when outlier failure data were considered. The investigation also examined the failure modes, observing multiple cracks for higher loads and single cracks that initiated on the surface or from internal inclusions at lower loading. The present investigation aims to provide a fatigue resistance prediction model encompassing the HCF and VHCF regions for the fatigue design of railway wagon leaf springs, or even for other components made of 51CrV4 with a tempered martensitic microstructure.

Bio-inspired curved beam structure subjected to bending load: Design, modelling, and experiment

Bio-inspired curved beam structure subjected to bending load: Design, modelling, and experiment

Combined Loading Effects on the Buckling Strength of Q690 Steel Tubes: An Experimental and Numerical Study

Abstract: This study investigates the stability and buckling behavior of Q690 high-strength steel cylindrical tubes subjected to combined axial compression and bending loads. Experimental testing on 27 specimens, combined with finite element analysis using ABAQUS, revealed critical insights into load-bearing capacity, deformation patterns, and failure modes. The study found that geometric imperfections, such as initial out-of-roundness and local dents, and residual stresses significantly influenced the buckling strength of the tubes, particularly those with high diameter-to-thickness ratios. Finite Element Analysis (FEA) effectively modeled the complex behavior, with deviations from experimental results ranging from 5.6% to 7.9%. Based on these findings, design recommendations, including optimized D/t and slenderness ratios, are proposed to enhance structural safety and efficiency. These results contribute to a better understanding of Q690 steel behavior and can inform the development of improved design codes for critical infrastructure applications

Effect of Infill Density on the Mechanical Properties of Natural Peek Processed by Additive Manufacturing

In the present investigation, the mechanical properties of natural polyether-ether-ketone (PEEK), processed by additive manufacturing applying fused deposition modeling (FDM) with three different infill densities, are investigated. Mechanical characterization was performed through destructive testing. Specimens were designed in CAD software and printed with controlled infill densities of 40%, 70%, and 100%, using a rectilinear pattern. The results showed that increased infill density improves mechanical strength and stiffness but reduces ductility and energy absorption capacity. For considered infill densities, maximum stress levels reach values of 107.53±6.29MPa, 114.32±11.95MPa, and 63.96±2.39MPa, respectively, against compression, bending, and tensile loading. These findings offer crucial information for optimizing infill density in manufacturing high-strength components for industrial and biomedical applications. As a result, practical guidelines are provided for the design of medical devices, such as implants, achieving an appropriate balance between mechanical performance and material efficiency.

Bending performance and design of reinforced concrete ribbed bridge deck slabs retrofitted with steel-plate reinforcement

ABSTRACT This study aimed to assess the bending performance and design of reinforced concrete ribbed bridge deck slabs with steel-plate reinforcement. Two reference members and three steel-plate reinforcements were designed for four-point bending loading tests, numerical simulations, and theoretical analyses. Steel-plate reinforcement improves the flexural load bearing capacity and stiffness of the bridge deck slab and effectively controls crack development, compared to old bridge reconstruction requirements. The bridge deck is best stressed when the bolt (M12 mm × 200 mm) spacing is 0.8 times the slab thickness. To prevent brittle damage to the bridge deck, a steel plate with a width of 160 mm and thickness of 10 mm should be used for strengthening. This aligns with engineering practice whereby the bolt shear capacity is used to assess the effectiveness of steel-plate reinforcement in bridge deck slabs. Bolt shear arrangement based on the slip effect and a sufficient increase in the diameter of the bolts at both ends of the steel plate are more appropriate for the bending effect of the bridge deck structure. The results provide a reference for the design of deck slab reinforcement for assembled ribbed bridges.

Biomechanical evaluation of the modified proximal femoral nail for the treatment of reverse obliquity intertrochanteric fractures

The best treatment method for reverse obliquity intertrochanteric fractures (ROIFs) is still under debate. Our team designed the modified proximal femoral nail (MPFN) specially for treating such fractures. The objective of this research was to introduce the MPFN device and compare the biomechanical properties with Proximal Femoral Nail Antirotation (PFNA) and InterTAN nail via finite element modelling. An AO/OTA 31-A3.1 ROIF model was established via Mimics software. Three implants were depicted and assembled on the ROIF models. The axial, bending, and torsion loads were simulated to test stress and displacement of three fixation models. Compared to the PFNA and InterTAN models, the MPFN model had more dispersed stress distribution under axial loads of 2,100 N. The MPFN showed lower von Mises stress on bones compared with that of PFNA and InterTAN in axial loads. In term of maximum displacement, the MPFN had a 12.6% reduction compared to the PFNA model in axial load case. In bending and torsion loads, the MPFN model also demonstrated better biomechanical properties than the PFNA and InterTAN models. The modified proximal femoral nail presented the best biomechanical performance, followed by the InterTAN nail, and the PFNA for fixing reverse obliquity intertrochanteric fractures. The MPFN has the potential to be a promising device for patients with ROIFs.

Characterizing the Movement of Thin Concrete Overlay Panels Subject to Truck Loads

The construction of thin concrete overlays as a pavement preservation option for both asphalt and concrete pavements is gaining popularity in the U.S. To reduce costs, as well as mitigate tendencies toward curling and warping, most thin bonded and unbonded concrete overlays are constructed with either smaller panels, or shorter length panels with undoweled transverse joints. Similar to undoweled concrete pavements on grade, thin undoweled concrete overlay projects have developed faulting of the transverse joints, sometimes at an early age. Toward the efforts to understand the mechanisms causing joint faulting in thin concrete overlays, this study sought to characterize the basic surface movements of thin overlay panels, including bending, translation, and joint load transfer, when subject to heavy vehicle loads. This study utilized digital image correlation (DIC) equipment to measure the dynamic displacement along the edge of thin bonded and unbonded concrete overlay panels loaded by heavy trucks. Testing showed that as the heavy front axle first lands on a thin overlay panel, localized bending is the predominant movement, regardless of panel length. For bonded concrete overlays on asphalt, most transverse joints did not show strong load transfer behavior, even when fiber-reinforced concrete was used. In addition to characterization of the panel surface movements, general correlation to observed joint faulting and panel distress was described. The findings from this study should serve useful to the continuing determination of the mechanisms causing joint faulting in thin concrete overlays

Investigation of the structural performance and failure mechanisms of 3D printed continuous carbon fiber‐based composites

AbstractAdditive manufacturing of continuous fiber‐based polymeric composites has attracted global attention. This contemporary technology enables the flexibility of manufacturing customized, partially and fully functional, and advanced composite components for numerous semi‐structural and structural applications. The current study investigates the structural performance of 3D‐printed carbon fiber‐based composites in the context of tensile, flexural, and high‐cycle fatigue. The crucial S‐N curves for the unidirectional (UD) (0°) and cross‐ply (CP) (0, 90) composites have been plotted. The dominating failure mechanisms responsible for the failure of 3D printed composites under tensile, flexural, and high cycle fatigue loading at the micro‐scale have been thoroughly investigated. The influence of fiber orientation on the failure mechanisms under different structural loading has been rigorously studied. The current findings conclude that cross‐ply (0, 90) composites exhibited superior fatigue performance than the unidirectional composites when investigated at 70% of their ultimate tensile strength. The current investigation reveals that the formation of voids during 3D printing and majorly during loading is one of the leading causes of the failure of additively manufactured composites under mechanical and cyclic loads. The fiber pull‐out, fiber breakage, de‐bonding, and voids are the dominating failure mechanisms observed under tensile loading. In addition to the failure mechanisms listed under tensile loading, matrix fractures have also been observed under flexural loading. The dominating failure mechanisms differed for UD, CP (0, 90), and CP (45, −45) composites.Highlights Investigated tensile, flexural, and fatigue properties of continuous fiber 3D‐printed composites. Examined failure mechanisms under tensile, bending, and fatigue loading. Developed test coupons with built‐in tabs for tensile and fatigue testing. Cross‐ply composites showed better fatigue performance than unidirectional.

Разрушение хрупких балок при антисимметричном четырехточечном изгибе

The nucleation of cracks in structural elements during their service life is due to the degradation of the material or the presence of hidden defects. The structure therefore loses its original load-bearing capacity and fails under significantly lower external loads. As a rule, the fracture of structures due to crack growth occurs under mixed loading. In this paper, an eccentric beam of rectangular cross-section with an edge crack subjected to antisymmetric four-point loading is considered. By changing the position of the crack relative to the center of the beam, it is possible to obtain the entire range of mixed fracture modes: I+II, pure I and pure II modes. Using the finite element method, stress intensity coefficients for modes I and II of failure, as well as T-stresses, were obtained for different geometric parameters of the beam and different loading conditions. The length of the crack, its position relative to the beam center, and the length of the short span were varied. The methods commonly used for calculating T-stresses were analyzed. In the element closest to the crack tip, strong displacement oscillations, not mentioned in the literature, are observed, therefore to determine T-stresses with the highest possible accuracy it is suggested to calculate them from displacements, cutting off the 3-4 nodes closest to the crack tip. Experimental studies of the fracture toughness of ebonite in a mixed mode were carried out. For each type of loading and geometry, 3-5 identical specimens were tested. The tests were carried out under static load until the specimens were completely destroyed. In all experiments, the crack initiation angle and critical load were recorded. Six failure criteria were used to predict both failure direction and critical load: the generalized maximum tangential stress criterion, the extended maximum tangential strain criterion, the generalized strain energy density criterion, the generalized maximum averaged stress criterion, the maximum elastic energy release rate criterion and the generalized maximum elastic energy release rate criterion. The results obtained demonstrate good agreement between the experimental values of critical loads and the numerical calculations. The error in determining the crack initiation angle does not exceed 5%. Considering that the experimental results agree with the predictions of failure criteria for the beam subjected to antisymmetric four-point bend loading, this type of a beam specimen can be used to study mixed-type fracture in the elements manufactured from engineering materials, such as, for example, plexiglass, ebonite, and getinax.

A Correlation Analysis-Based Structural Load Estimation Method for RC Beams Using Machine Vision and Numerical Simulation

The correlation analysis between current surface cracks of structures and external loads can provide important insights into determining the structural residual bearing capacity. The classical regression assessment method based on experimental data not only relies on costly structure experiments; it also lacks interpretability. Therefore, a novel load estimation method for RC beams, based on correlation analysis between detected crack images and strain contour plots calculated by FEM, is proposed. The distinct discrepancies between crack images and strain contour figures, coupled with the stochastic nature of actual crack distributions, pose considerable challenges for load estimation tasks. Therefore, a new correlation index model is initially introduced to quantify the correlation between the two types of images in the proposed method. Subsequently, a deep neural network (DNN) is trained as a FEM surrogate model to quickly predict the structural strain response by considering material uncertainties. Ultimately, the range of the optimal load level and its confidence interval are determined via statistical analysis of the load estimations under different random fields. The validation results of RC beams under four-point bending loads show that the proposed algorithm can quickly estimate load levels based on numerical simulation results, and the mean absolute percentage error (MAPE) for load estimation based solely on a single measured structural crack image is 20.68%.

Load Testing Application for Truss Bridge Design Verification: Live Load Testing

This is the second of two companion papers discussing application of load testing techniques for verification of bridge design. The bridge was a six-spans continuous steel truss structure, about 338-m long and 14.45-m wide, in the State of New York. Design of the bridge was completed using an unconventional approach where the top chords of the main trusses, floor beams, and stringers were designed to act composite with the concrete deck. In addition to axial forces, such a design also gives rise to secondary moments in the truss main members under design loads. This aroused interest in verification of the design through an instrumentation, monitoring, and load testing program. Comparing the members’ actual service load axial forces and moments with those used in the design, it was concluded that axial forces were overestimated in the design by about 20 percent for service dead load and by about 25 percent for service live load. Similar comparison for moments, indicated that service dead load moments were within 20 percent of those used in the design and service live load moments were underestimated by about 55 percent. The above differences for service dead load can be attributed to the way the deck pours were accounted for in the design and the possibility of construction loads being on the structure during the deck pour monitoring. For service live load, these differences can be explained by possible discrepancies in estimating service live load from the test results and the fact that the analysis for service live load in the design was performed ignoring the contribution of the composite concrete deck. Adequacy of the structural design under actual axial forces and moments was confirmed by checking the AASHTO interaction equations for steel members under combined axial and bending loading conditions. The major contribution of this and the companion paper is that, they introduced a new approach for estimating total dead load effects by only monitoring strains in a limited number of truss members during staged deck construction and load testing of a very large truss bridge structure, it validated the unconventional design under both dead load and live load as a viable method for design of truss bridge structures, and it supplemented the very limited literature on dead load monitoring of bridges.

Bending Performance of Diamond Lattice Cylindrical Shells.

The Diamond lattice cylindrical shell (Diamond LCS) was proposed by a mapping approach based on the triply periodic minimal surfaces (TPMS). The finite element models were built and their accuracy was verified by experimental results. Parameter studies were carried out to investigate the effect of geometric and loading parameters on the bending properties of the Diamond LCSs by the finite element model. The results show that Diamond LCS has a stable "V" deformation pattern under a three-point bending load. In the range of relative density (RD) = 15-30%, the higher the RD, the better the lateral bending performance of the Diamond LCS structure. The larger the variation radial coefficient, the higher the lateral load-carrying capacity of the structure. The smaller the loading angle of the punch, the better the lateral bending performance of the Diamond LCS structure. However, if the loading angle is too small, the structure is prone to large torsional deformation, and the deformation tends to destabilize. The increase in punch diameter effectively improves the deformation pattern and bending energy absorption characteristics of the structure. The smaller the span of the cylindrical support, the better the bending energy absorption characteristics of the structure.

Bending behavior of needle‐punched carbon/carbon composites: Efficient computation model

AbstractNeedle‐punched carbon/carbon composites (NP C/Cs) are advanced materials widely used in aerospace applications. The needle‐punching technique improves the structural integrality of carbon‐fiber plies; however, it also introduces many defects affecting the mechanical behavior of NP C/Cs. To investigate the behavior of needle‐punched carbon/carbon composites under bending loads, a circular‐arc beam element with a needle‐hole defect is developed to model the punched carbon fibers and an extended spring element is suggested to model the matrix. This model allows quick predictions of the bending modulus, strength and progressive damage of NP C/Cs. It is shown that efficient numerical predictions agree well with the experimental results, thus validating the proposed method.

Construction of a one-layer equivalent model for a base material strengthened by two-layer bonded CFRP plates under bending load

Construction of a one-layer equivalent model for a base material strengthened by two-layer bonded CFRP plates under bending load

Evaluating failure modes through energy dissipation mechanisms in hybrid composites under bending loads

Evaluating failure modes through energy dissipation mechanisms in hybrid composites under bending loads