Bending Zone Research Articles

Study on the Influence of Transition Zone Position on Bending Spring back of TRBs

In this paper, the crystal plastic finite element method is used to study the influence of the transition zone position of Tailor Rolled Blank (TRB) on the bending deformation behavior and spring-back from the mesoscale. The polycrystalline plastic finite element bending model of TRB is established and the bending forming process was simulated. The results show that the B-shaped blank (the blank consists of thick zone and transition zone) has a uniform plastic deformation and a smaller spring-back value than the A-shaped blank (the blank consists of thin zone and transition zone). The stress-strain zone of the B-shaped blank is uniform spread from the bend zone to both sides, but the stress-strain area of the A-shaped blank is transferred to the transition zone, which makes the blank exhibit poor forming properties. And this deformation ununiformity makes the spring-back angle of the A-shaped blank larger than that of the B-shaped blank.

Salt tectonics in the Bend Zone segment of the Carpathian fold and thrust belt, Romania

The Carpathian Bend Zone is part of the Eastern Romanian Carpathians. The stratigraphic profile contains two levels of salt: Lower Miocene (Lower Burdigalian) and Middle Miocene (Badenian). The studied segment of the fold belt was deformed during the Middle Miocene (Badenian-to-Middle Sarmatian phase) and during the Late Miocene to present (Wallachian phase). During this latter phase, the Lower Burdigalian salt was remobilized and reached the surface on several locations piercing through 2–3 km-thick post-tectonic deposits. The salt outcrops and contractional structures now form a 30 km long, NE–SW lineament at the surface. This contribution proposes kinematic models for the Lower Burdigalian salt movement during both tectonic phases. The lineament was a detachment fold in the Middle Miocene phase. Thickened Burdigalian salt and Oligocene s.l. duplex filled the core of the detachment fold. The detachment fold was subsequently peneplained with the Burdigalian salt exposed on the paleo-surface that locally redeposited during the Badenian. The Wallachian evolution is less clear and we propose two viable kinematic models. It is possible that the salt rise kept up with sedimentation and halokinetic sequences formed at the salt–sediment interface. Alternatively, the area was reactivated in a thin-skinned, right-lateral strike–slip manner with local pull-apart basins (1–2 km across) providing space for salt plugs. Currently available data do not allow us to pick a preferred model for the kinematics during the Wallachian phase. Both kinematic models are novel and are in contrast with earlier ideas.

The sustainability of micropolar concrete plasticity model to the finite element size

Introduction. As it is known, deformation of concrete can be divided into several stages. The first stage is characterized by a linear dependence of deformations and stresses, elastic deformations and small loads that, as they increase, lead to the second stage. At the second stage, the dependence becomes curvilinear, while deformations are irreversible, since micro-cracks are formed. Further consolidation of the micro-cracks into meso- and main cracks refers to the third stage and is accompanied by a redistribution of energy to the area of the main crack mouth. However, reaching the ultimate strength is not accompanied by an instant loss of bearing capacity due to the effect of decompression. This phenomenon should be taken into account in the numerical simulation of concrete and reinforced concrete structures, because it significantly affects their strength characteristics. The introduction of such a refinement in the design models will allow reducing cross-sections of the construction components and accordingly getting rid of material overruns.
 Materials and methods. A digital sample is created for the study using the ANSYS software. A beam model is simulated as a single-span beam with longitudinal reinforcement in the bending zone. The load is applied as a 70 mm offset to the nodes in the line along the application point. Reinforcement is simulated as bilinear isotropic strengthening elements (LINK180). For uniform load distribution, load plates with linear elastic properties are specified at the points where boundary conditions and load are applied.
 Results. According to the obtained data, stress-deformation curves are constructed identically to the concrete deformation diagram. The values of loads when the first cracking occurs (end of the linear-elastic state), peak loads when the main crack is formed (maximum load for the unreinforced case and the beginning of the steel softening for the reinforced case) as well as ultimate loads and maximum deflections at the mid-span are compared.
 Conclusions. The results give insignificant (up to 5 %) discrepancies when changing the finite element size. Therefore, when working with calculation software, developers will be able to create correct models with any spacing of the finite element mesh depending on the available computational capabilities. Micropolar theory for simulating the concrete decompression can be considered sustainable to the size of the finite elements.

Structure and Mechanical Properties of Cold-Deformed Galvanized Rolled Sheets for Light Thin-Walled Constructions

The influence of the cold plastic deformation that appear in bending zones and subsequent strain aging on the brittle fracture resistance of galvanized low-carbon steel sheets (2.0–3.0 mm thick) intended for light thin-walled constructions is studied. At low temperatures (from –55 to –70°C), cold working followed by strain aging is shown to substantially decrease impact toughness KCU and the fraction of the ductile component in the fracture surface of a steel sheet. The effect of the ferrite grain size on the susceptibility of steel sheets to brittle fracture, in particular, KCU ~ 1/ $$\sqrt d $$ , where d is the ferrite grain size in the rolling plane, is found.

Functional morphology and structural characteristics of the hind wings of the bamboo weevil Cyrtotrachelus buqueti (Coleoptera, Curculionidae)

ABSTRACTResearch data of the microstructure and surface morphology of insect wings have been used to help design micro air vehicles (MAV) and coating materials. The present study aimed to examine the microstructure and morphology of the hind wings of Cyrtotrachelus buqueti using inverted fluorescence microscopy (IFM), scanning electron microscopy (SEM), and a mechanical testing system. IFM was used to investigate the distribution of resilin in the hind wing, and SEM was performed to assess the functional characteristics and cross-sectional microstructure of the wings. Moreover, mechanical properties regarding the intersecting location of folding lines and the bending zone (BZ) were examined. Resilin, a rubber-like protein, was found in several mobile joints and in veins walls that are connected to the wing membranes. Taken together, structural data, unfolding motions, and results of tensile testing suggest two conclusions on resilin in the hind wing of C. buqueti: firstly, the resilin distribution is likely associated with specific folding mechanisms of the hind wings, and secondly, resilin occurs at positions where additional elasticity is needed, such as in the bending zone, in order to prevent structural damage during repeated folding and unfolding of the hind wings. The functional significance of resilin joints may shed light on the evolutionary relationship between morphological and structural hind wing properties.

Behavior of RC box beam strengthened with basalt FRP using end anchorage with grooving

In recent days, many structures are strengthened with fiber-reinforced polymer to make use of the existing reinforced concrete structures to the current needs. Although investigations on the behavior of undamaged fiber-reinforced polymer-strengthened reinforced concrete beams anchored with U-strips have been conducted, study on the behavior of RC box beams strengthened with basalt fiber-reinforced polymer using end anchorage with grooving is still lacking. In the present study, the failure mode, ductility, stiffness, and loading-carrying capacity of an RC box beam strengthened with basalt fiber-reinforced polymer using end anchorage with grooving were experimentally and analytically investigated. Test results and analysis showed that: (1) the average crack spacing, average crack depth, and average crack width of specimen anchored with grooving decreased by 10.3%, 2.8%, and 6.2% when compared with that of specimen anchored with U-strips, respectively; (2) the failure mode of specimen anchored with grooving was basalt fiber-reinforced polymer debonding in pure bending zone; (3) the deflection or curvature ductility of specimen anchored with grooving was 33.9% or 32.7% lower than that of specimen anchored with U-strips; (4) a model based on built-up bars for the load-carrying capacities of BFRP-strengthened beams anchored with grooving was proposed.

Research on roll forming process based on five-boundary condition forming angle distribution function

Process parameters crucially influence product quality in complex roll-forming process. Improper setting of process parameters can cause springback and peak longitudinal strain, resulting in product defects. In the present study, the main process parameters considered are forming angle and sheet thickness. The forming angle for each pass of forming is allocated reasonably by applying a five-boundary condition, which forms an angle distribution function, to further study the effects of sheet thickness and material properties on the peak longitudinal strain and springback. Moreover, transverse strain in the bending zone was studied based on the microstructure of the sheet used herein. The results of finite element simulation and experiments demonstrate that the peak longitudinal strain increases with increase in the forming angle. The peak longitudinal strain decreases with the sheet thickness increases, while the transverse strain increases with the sheet thickness increases. The springback decreases with the increase of sheet thickness under the condition of a certain roll radius. The continuous forming springback angle between the first and the ninth forming passes was only 0.5° in the paper. The peak longitudinal strain and springback are closely related to material properties.

Middle Miocene evolution and structural style of the Diapir Fold Zone, Eastern Carpathian Bend Zone, Romania: insights from scaled analogue modelling

Abstract The Diapir Fold Zone of the Carpathians is the most prolific onshore hydrocarbon area in Romania. Structural complexity, mainly due to the presence of salt, combined with poor seismic quality near and below the salt lead to contrasting structural models in the area. To gain insights into the mid-Miocene tectonic evolution, structural geometries and the effects of penetrative strain, we ran dual décollement scaled sandbox models with layered brittle and ductile materials. Results of two analogue models (20 and 33% shortening) revealed that the onset of the deformation sequence was mainly characterized by layer-parallel shortening. As shortening continued, a foreland-verging sequence of supra-salt detachment folds and sub-salt duplexes evolved. The sub-salt duplexes are located directly below the crests of the detachment folds, as the development of these large wavelength anticlines was related to sub-salt deformation. Salt flow was another controlling factor of the deformation style, as salt accumulated in the anticlinal cores and increased the coupling in the supra-salt synclinal axis. Our results offer insights into the effects of salt on the kinematic evolution of this area, help to predict geometries in areas of poor seismic quality, and highlight the important contribution of penetrative strain on deformation and reservoir quality.

Shear strength of fiber-reinforced high-strength steel ultra-high-performance concrete beams based on refined calculation of compression zone depth considering concrete tension

This article presents an experimental and theoretical investigation on the shear behavior of fiber-reinforced ultra-high-performance concrete beams reinforced with high-strength steel. The test parameters included the fiber volume fraction, fiber type, and stirrup ratio. The test results indicate that the shear failure in ultra-high-performance concrete beams is not brittle and catastrophic but has ductility characteristics. A moderate quantity of stirrups can significantly improve the shear behavior of ultra-high-performance concrete beams, as reflected in the thorough propagation of cracks in both shear span and pure bending zone. The depth of the compression zone considering concrete tension was derived based on the deformation compatibility and force equilibrium equations for both serviceability limit state and ultimate limit state. The comparison of the proposed method and classical beam theory shows that the concrete tension should not be neglected in the serviceability limit state analysis. After cracking, the concrete tension can be neglected for simplicity when the beam is heavily reinforced and should be considered when the beam is lightly reinforced. Then, a shear strength model was established based on Rankine’s failure criteria, the truss model, and Association Francaise de Génie Civil-Sétra. Finally, the proposed shear strength equation was verified by the test results and compared with other shear strength equations.

ISOLASI LIKOPEN DARI BUAH TOMAT (Solanum lycopersicum L) dan UJI AKTIVITAS LIKOPEN TERHADAP BAKTERI Salmonella thypi

This research aims to know the effectiveness of lycopene antibacterial, through knowing bending zone lycopene towards salmonella thypi. This research has been success to isolate lycopene through extraction process used reflux method at 60oC temperature, using chloroform and methanol as antisolvent. Lycopene extract got 5,12 mg/100 g, analysis of functional groups by using spectroscopy Fourier Transform InfraRed (FTIR) detected C=C alkena alifatik at 1674,91 dan 1639,65 cm-1 wave length, C-H(CH3) detected at 1378,71 cm-1 wavelength, C-H (stretching) alifatikfunctional groups detected at 2853,12 cm-1 wave length, C-H alkena (stretching) detected at 2924,16 cm-1 wave length, and C-H alkena (bending) detected at 1498,86 cm-1 wave length. Inhibitory zone testing of salmonella thypi used paperdisc method with three repetitions. The mean diameter of the inhibitory zone of bacteria formed in positive control was 33,17 mm, negative control was 0 mm. Mean diameter of bacterial inhibitory zone at 3 % concentration with 3, 68 mm mean diameter and maximal Inhibitory zone at 50 % concentration with 15,12 mm mean diameter . The result of this research shown that lycopene extract has bacterial activity towards salmonella thypi Kewords: Isolation, Lycopene, Salmonella thypi, Antibacterial

Fracture evolution and gas transport laws of coal and rock in one kilometer deep coal mine with complicated conditions

As coal mining gradually extends deeper, coal seams in China generally show high stress, high gas pressure and low permeability, bringing more difficulty to coal mining. Therefore, in order to strengthen gas extraction, it is necessary to carry out reservoir reconstruction after deep coal seams reached. In this paper, the distribution and evolution laws of fracture zone overlaying strata of J15 seam in Pingdingshan No. 10 coal mine after excavation were studied by combining similar simulation and numerical simulation, meanwhile, the gas transport law within fracture zone was numerically simulated. The results show that the fracture zone reaches a maximum of 350 mm in the vertical direction and is 75 mm away from W9,10 coal seams in vertical distance. Since W9,10 coal seams are in an area greatly affected by the bending zone of J15 coal seam under the influence of mining, the mining of J15 coal seam will exert a strong permeability enhancement effect on W9,10 coal seams. The J15 coal seam can act as a long-distance protective layer of W9,10 coal seams to eliminate the outburst danger of the long-distance coal seams in bending zone with coal and gas outburst danger, thereby achiev?ing safe, productive and efficient integrated mining of coal and gas resources. The gas flux of mining-induced fractures in the trapezoidal stage of mining-induced fracture field is far greater than that in the overlaying stratum matrix. The horizontal separation fractures and vertical broken fractures within the mining-induced fracture field act as passages for gas-flow. Compared with gas transport in the overlaying stratum matrix, the horizontal separation fractures and vertical broken fractures within the mining-induced fracture field play a role in guiding gas-flow. The research results can provide theoretical support for the arrangement of high-level gas extraction boreholes in roof fracture zones.

К РАСЧЕТУ КРИВИЗНЫ ЖЕЛЕЗОБЕТОННЫХ БАЛОК НА ОСНОВЕ ДЕФОРМАЦИОННОЙ МОДЕЛИ

The article considers the basic prerequisites for the calculation of reinforced concrete structures based on the deformation model. The main features and calculation options are indicated. Deformation diagrams have been selected to calculate reinforced concrete beams, including those using indirect reinforcement of the compressed zone. The work of concrete in the stretched area after the formation of normal cracks is taken into account by switching to the diagram of the average deformation of the reinforcement σ sm -e sm by introducing the coefficient ψ s into the calculations. For three series of reinforced concrete beams the results of calculating the curvature in the zone of pure bending with the coefficient ψ s and without are presented. Comparison with the results of the experiments is shown.

Deformation and Subsidence prediction on Surface of Yuzhou mined-out areas along Middle Route Project of South-to-North Water Diversion, China

AbstractThe Middle Route of the South-to-North Water Diversion Project crosses the coal mined-out area in Yuzhou city. There are 4 mined-out areas along Yuzhou section of the water diversion project. The collapse, fracture and deformation of overlying rock mass occurred due to strata loss and stress field change, which then resulted in the subsidence, collapse fissures on the ground. The deformation of the upper rock mass is characterized by “three-zone”: caving zone, fault zone, and bend zone. Thus, it is very important to predict the surface subsidence of the mined-out areas. Highly precise deformation observation network were set along the channel. The monitoring data show that the surface tilt, curvature and horizontal deformation of the mined-out areas were less than critical values. However, the forecast and monitoring values are relatively larger in Guocun and Xinfeng mined-out areas due to large mining range and the possible location of two mined-out areas in the affected region. Therefore, the monitoring should focus on the two mined-out areas.

Experimental Investigation Dowel Action of Longitudinal Reinforcement of Reinforced Concrete Beams

The technique and results of experimental investigation on test samples of shear force magnitude (dowel action) in longitudinal tensile reinforcement in the zone of transverse bending of reinforced concrete beams after the formation of inclined cracks are presented in the article. The design of test samples, the technique of measurement of deformations at carrying out tests is described. Deformations along the length of reinforcing bar were determined by means of chains of strain gauges pasted on the upper and lower faces of the reinforcing bar. According to the results of the study, the distribution of deformations along the length of reinforcing bars in the zone of transverse bending at different stages of loading is established. The experimental values of bending moments and shear forces in reinforcing bars after the formation of an inclined crack and in the failure stage were determined according to the readings of strain gauges. An analysis of the experimental data is performed and a comparison is made between the experimental values of the dowel action of the longitudinal reinforcement of reinforced concrete beams at the intersection of an inclined crack, depending on the percentage of longitudinal reinforcement of section.

Features of finite element analysis of steel-reinforced concrete slabs from hollow core slabs

The present article is devoted to the calculation and finite element analysis of steel-concrete composite slabs from precast hollow-core slabs in the software package ABAQUS with the use of ABAQUS/Explicit and ABAQUS/Standard solvers taking into account the installation stage. The behaviour of the fragment imitating the steel-reinforced concrete work section on the basis of a beam with a zone of equal deformations is considered. The load was applied to two beam nodes at a distance of 0.5 m from the support, thus forming a zone of pure bending at the site of the slab’s inclusion in the beam work. The inclusion in the work of precast hollow-core slabs is provided by the installation of stud anchor on the slab’s ends welded to the upper flange of the beam, while the length of the support plates increasing. Based on finite element analysis, carried out engineering and theoretical studies, the authors obtained dependences describing the behaviour of steel-concrete composite slabs. The analysis of the results showed good convergence of the finite element analysis results and theoretical solutions. The discrepancy between the results of finite element analysis and theoretical methods was less than 5%.

Post-spreading deformation and associated magmatism along the Iberia-Morocco Atlantic margins: Insight from submarine volcanoes of the Tore-Madeira Rise

A new high-resolution bathymetric map combined with a regional Digital Elevation Model (DEM) analysis reveal the modalities of occurrence and emplacement of post-spreading magmatism along the NNE-SSW oriented, 1000 km long Tore-Madeira Rise (TMR) as well as its relationship with the activity of major fault systems including the Estremadura Fault System (ESF) and the Azores-Gibraltar Fracture Zone (AGFZ). Morphological and structural analysis of the bathymetric map were performed to map volcanic features such as eruptive cones, vents and fissures together with faults along the TMR. The new bathymetric map shows that the main NNW-SSE seamount alignment is formed by three structurally distinct volcanic massifs, the Tore, the Josephine and the Southern Volcanic Groups. The majority of the volcanoes of each group emplaced within or along specific portion of pre-existing faults (ESF and AGFZ) including splay fault, releasing bend, fault tips and interaction zones between different segments. Magmas were channelled into sub-vertical pre-existing lithospheric faults that acted as preferential pathways for the vertical magma ascent. Migration and final eruption of magma are controlled by the local stress variation induced by complex fault geometries, change in plate kinematics as well as strong shear zone anisotropy as suggested by the emplacement within localised areas of transtension. We conclude that post-spreading magma emplacement in the southern part of the Iberia margin was related to the development of a transtensional plate boundary between the Iberian and African Plate during the Late Cretaceous. More generally, our findings emphasize that the distribution of volcanism as the expression of the interaction between shallow plate tectonic and mantle processes should be included in plate kinematic reconstruction. This study also demonstrates that the accurate mapping of oceanic seafloor is pivotal to better understand tectono-magmatic evolution of volcanic seamount chains and geological processes in oceanic domains.

Experimental and finite element analysis of surgical drill bits with and without irrigation channel – A case study approach

The aim of this study was to perform a finite element and experimental comparative analysis of the mechanical characteristics of surgical drill bits used in bone and joint surgery applications with and without an irrigation channel. Internally cooled drills are very efficient in maintaining the drilling temperature below the critical level. However, a cooling channel could potentially have a negative influence on the drill structure, particularly in the flutes zone. A commercially available type of surgical drill bit without irrigation channel and a modified variant with the built-in channel were simultaneously loaded with torque, axial and bending forces with magnitudes similar to and higher than those utilized in clinical practice. When loaded under the same conditions, both types of drills showed very similar mechanical properties in the sense of the average von Mises stress in chosen sections and the deflections after plastic deformation. The highest stress was observed in the bending zone which was located at the beginning of the flutes section of the drill. All analysed drills suffered only from plastic deformation without any breakage despite the fact that they were loaded with forces higher than those expected in normal operational conditions.

Active tectonic deformation and associated earthquakes: a case study—South West Carpathians Bend zone

Active tectonic deformation is continuously shaping the landscape in the Alpine Orogenic system. Earthquakes are clear proves of neotectonic deformation process. In the Romanian Carpathians the most active deformation is recorded in the South Eastern Carpathian Bend Zone. Nevertheless, seismicity associated to latest orogenic stage of active deformation is not limited to this area. Other seismic regions, like the South West Carpathians Bend Zone, were identified. Recently, several earthquake sequences were recorded in the Caransebes-Mehadia (CMB) and Hateg basins (HB). These sedimentary basins developed over the South Carpathians, Getic/Supra Getic and Danubian basement napes, their evolution being related with the N-ward tectonic transport of the Carpathian Orogen, in the current position, during the Paleogene-Quaternary times. The aim of the present study is to perform a thorough analysis of the earthquakes recorded in these two basins in correlation with the observed geological structure to better understand and constrain the neotectonic processes affecting the SW Carpathians Bend Zone. The focal mechanisms determined for HB show a predominant strike-slip faulting component with the principal axes oriented approximately NW–SE (compression) and NE–SW (extension), a reorientation from the N-S one described for the Pliocene–Pleistocene phase. The focal mechanisms in CMB imply N–S extension with normal or strike-slip faulting. We argue that the present day tectonic processes are not restricted to the SE Carpathians Bend zone, as previously inferred. Instead they affect a much larger area of the Carpathian Orogen, like the SW Carpathians Bend zone.

Influence of web openings on bearing capacity of triangularly corrugated web beam

The paper presents a study on the behaviour of corrugated web steel beams with and without web openings. Examined steel beams consist of two flanges and a thin triangularly corrugated web, connected by automatic welding. In the literature, the web opening problem in steel beams was dealt with mostly for steel beams with plane webs and research of the effect from opening in a corrugated web was found out to be very limited. A finite element analysis in ABAQUS software was carried out to investigate the effect of openings in corrugated web. A number of beams FE models comprise of web openings with different sizes and positions were developed. The effect on beam bending capacity of circular opening in corrugated web is studied for various openings positions and sizes also as corrugation density. The stress concentration factors are obtained near the circular opening in cases of its location in zone of pure bending and in zone of transverse bending of the beam. Recommendations are given for practical design of corrugated web beams weakened by circular openings.

Biomechanical evaluation of interbody fixation with secondary augmentation: lateral lumbar interbody fusion versus posterior lumbar interbody fusion.

Many approaches to the lumbar spine have been developed for interbody fusion. The biomechanical profile of each interbody fusion device is determined by the anatomical approach and the type of supplemental internal fixation. Lateral lumbar interbody fusion (LLIF) was developed as a minimally invasive technique for introducing hardware with higher profiles and wider widths, compared with that for the posterior lumbar interbody fusion (PLIF) approach. However, the biomechanics of the interbody fusion construct used in the LLIF approach have not been rigorously evaluated, especially in the presence of secondary augmentation. Spinal stability of 21 cadaveric lumbar specimens was compared using standard nondestructive flexibility studies [mean range of motion (ROM), lax zone (LZ), stiff zone (SZ) in flexion-extension, lateral bending, and axial rotation]. Non-paired comparisons were made among four conditions: (I) intact; (II) with unilateral interbody + bilateral pedicle screws (BPS) using the LLIF approach (referred to as the LLIF construct); (III) with bilateral interbody + BPS using the PLIF approach (referred to as the PLIF construct); and (IV) with no lumbar interbody fusion (LIF) + BPS (referred to as the no-LIF construct). With bilateral pedicle screw-rod fixation, stability was equivalent between PLIF and LLIF constructs in lateral bending and flexion-extension. PLIF and LLIF constructs had similar biomechanical profiles, with a trend toward less ROM in axial rotation for the LLIF construct. LLIF and PLIF constructs had similar stabilizing effects.