Tension Bending Research Articles

Retraction Notice: Mechanical Analysis of Stayed Bridge

Cable stayed bridge, also known as the cable-stayed bridge is of box girder with many cable directly to the towers is a kind of bridge, is by the pressure of the tower, tension of cable and bending bearing beams of a structure system. It can be considered as a continuous beam of multi span elastic supports for the cable instead of a pier. It can reduce the moment of the beam, reduce the height of the building, it reduce the weight of the structure and save the material. Stayed Bridge is a new form of bridge structure, The bridge structure special and complex forces, The deck transverse load and live load is to balance by tilting tower, By the general theory to analyze the cable-stayed bridge stayed bridge, The key is to consider the main tower tilt, Leaning further stress analysis, drawn stayed bridge mechanics analysis method.

Comparison of fracture test standards for a super pave dense-graded hot mix asphalt

The objective of this work is to compare the semi-circular bend (SCB) and disk-compact tension (DCT) fracture tests for asphalt-aggregate mixtures. Fracture tests are performed. Statistical analysis, digital image correlation, and 3D scans show that the SCB tests measure a low fracture resistance with a high coefficient of variation due to stress concentrations and plasticity developing at the anvil contact point. The DCT test is found to measure a high fracture resistance with a low coefficient of variation. The DCT tests is determined to provide a superior measurement of fracture resistance. Evidence concerning the physical problems with SCB is provided.

Experimental and numerical investigation of low-temperature performance of modified asphalt binders and mixtures

Thermal cracking is the prevalent type of distress experienced by asphalt pavements in cold regions. It is widely assumed that when thermal stresses induced in the pavement exceed the tensile strength of the asphalt surface layer, cracking occurs; however, the role of thermal fatigue should not be ignored. To better describe the low-temperature (LT) performance properties of modified asphalt binders, a new parameter, normalised tensile stress (NTS), was defined in this research. NTS values were compared with bending beam rheometer (BBR), direct tension (DT) and semi-circular bending (SCB) fracture test results. The m-value parameter of the BBR test specifies the type of asphalt binder. This classification changes as the loading time changes and is only valid in the linear viscoelastic range. It showed limited sensitivity to changes in the material properties of modified asphalt binders that showed superior LT damage resistance. In contrast, the results from the DT, SCB and NTS parameters were sensitive to the changes. The results of SCB testing and NTS parameters were in agreement with the existing field data. It was also found that the use of sulphur as a cross-linking agent improved the storage stability of styrene butadiene styrene (SBS)-modified asphalt binder and decreased the amount of SBS required to yield a comparable result by about 50%. In contrast to what has been reported by some investigators, the use of polyphosphoric acid as a cross-linking agent intensified the phase separation of bitumen and SBS, and somewhat reduced the efficacy of SBS modification with regard to LT performance.

Crack Growth Behavior of Pipes Made From Polyvinyl Chloride Pipe Material1

The behavior of crack growth of polymeric materials is affected by several operating conditions such as crosshead speed, specimen thickness, load line, and specimen configurations, which reverse the behavior of crack from stable to unstable crack growth behavior. The main objective of the present paper is the determination of plane strain fracture toughness (KIC) for polyvinyl chloride (PVC) used in piping water transmission systems. The dimensions of the PVC pipe are outside diameter, Do = 315 mm, standard dimensions ratio, SDR = 13.23, ratio between outside to inside radii Ro/Ri = 1.179, and pipe thickness, t = 24 mm. Curved specimens are prepared from a pipe by cutting 12 mm thickness ring segments. The curved specimens are divided into two specimen configurations, namely, curved three-point bend (CTPB) and C-shaped tension (CST) specimens. All specimens are provided artificially with a precrack. CTPB specimen is further cut into five 72 deg sectors with each being centrally notched to a depth approximately a = 0.479 of the wall thickness. CST specimen configuration is characterized by the eccentricity X = 0, and 0.5 W, of the loading holes from the bore surface. The linear elastic fracture mechanics theory (LEFM) is used to predict the plane strain fracture. The tests are carried out at room temperature, Ta equal 20 °C, and different crosshead speeds of (10–500 mm/min). The numerical analysis carried out within the frame of the present work is done using the finite element program Cosmos 2.6. Finite element method (FEM) is used to compute the stress intensity factor KQ surrounding the crack tip. The computed stress intensity factor can then be compared with that obtained by theoretical equation. The experimental fracture test results reveal that the crosshead speed has been proven to affect the mode of failure and mode of fracture. At lower crosshead speeds, the mode of failure is ductile, while at higher crosshead speeds, it is brittle. The specimen configuration also affects the fracture toughness. CST specimens show higher fracture toughness in the case of pin loading location X = 0.5W than X = 0 by about (12%). The transitional crosshead speed is affected by specimen geometry. CST specimens (CST) at X = 0 and 0.5W have higher transitional crosshead speed compared with the CTPB specimen configuration.

Anisotropy of B-DNA Groove Bending.

DNA bending is critical for DNA packaging, recognition, and repair, and occurs toward either the major or the minor groove. The anisotropy of B-DNA groove bending was quantified for eight DNA sequences by free energy simulations employing a novel reaction coordinate. The simulations show that bending toward the major groove is preferred for non-A-tracts while the A-tract has a high tendency of bending toward the minor groove. Persistence lengths were generally larger for bending toward the minor groove, which is thought to originate from differences in groove hydration. While this difference in stiffness is one of the factors determining the overall preference of bending direction, the dominant contribution is shown to be a free energy offset between major and minor groove bending. The data suggests that, for the A-tract, this offset is largely determined by inherent structural properties, while differences in groove hydration play a large role for non-A-tracts. By quantifying the energetics of DNA groove bending and rationalizing the origins of the anisotropy, the calculations provide important new insights into a key biological process.

Negative Birefringence in the Higher Homologs of the 5O.m Series of Liquid Crystals.

A detailed study of the different parameters of the higher homologs of the 5O.m (m = 14, 16) series of liquid-crystalline compounds is reported. These are interdigitated compounds with unsymmetrical alkyl chain length. The compounds have a unique nature, unlike the other members of the nO.m series. The molecular structure reported in this article is not purely uniaxial; it has a bending tendency. In this article, we report that both the compounds exhibit negative birefringence. For the optical study, the refractive indices, ne and no, of the sample are measured by the thin-prism technique, using a He-Ne laser beam of wavelength 633 nm. A four-parameter model was used for fitting the experimental results. From the experimentally measured refractive indices, it is possible to compare different parameters with those of the theoretical models.

Analytical Solution for Vibration of a Rotating Delaminated Composite Beam with End Mass

In this paper, the free vibration of rotating laminated composite beams (LCBs) with general lay-ups and single through-the-width delamination is analytically investigated. The Hamilton’s principle is used to derive the coupled governing differential equations and boundary conditions for the rotating delaminated beam, considering the effects of shear deformation, rotary inertia, material couplings (bending–tension, bending–twist and tension–twist couplings), and Poisson’s effect. Both the free mode and constrained mode assumptions are adopted. Analytical solution for the natural frequencies and mode shapes are presented by incorporating the constraint conditions using the Lagrange multipliers method. The accuracy is assured by the convergence of the natural frequencies, as well as by comparison with published results. The effects of various factors such as delamination parameter, fiber angle, hub radius, material anisotropy, end mass and rotating speed are studied in detail. The difference between the results based on the free mode and constrained mode assumptions is also investigated.

Accelerated creep in solid oxide fuel cell anode supports during reduction

To evaluate the reliability of solid oxide fuel cell (SOFC) stacks during operation, the stress field in the stack must be known. During operation the stress field will depend on time as creep processes relax stresses. The creep of reduced Ni-YSZ anode support at operating conditions has been studied previously. In this work a newly discovered creep phenomenon taking place during the reduction is reported. This relaxes stresses at a much higher rate (∼×104) than creep during operation. The phenomenon was studied both in three-point bending and uniaxial tension. Differences between the two measurements could be explained by newly observed stress promoted reduction. Finally, samples exposed to a small tensile stress (∼0.004 MPa) were observed to expand during reduction, which is in contradiction to previous literature. These observations suggest that release of internal residual stresses between the NiO and the YSZ phases occurs during reduction. The accelerated creep should practically eliminate any residual stress in the anode support in an SOFC stack, as has previously been indirectly observed. This phenomenon has to be taken into account both in the production of stacks and in the simulation of the stress field in a stack based on anode supported SOFCs.

Surface flaws behavior under tension, bending and biaxial cyclic loading

Fatigue surface crack growth and in-plane and out-of-plane constraint effects are studied through experiments and computations for the aluminum alloy D16T. A tension/bending central notched plate and cruciform specimens under different biaxial loadings with external semi-elliptical surface cracks are studied. The variation of the fatigue crack growth rate and surface crack paths is studied under cyclic tension, bending and biaxial tension–compression loading. For the experimental surface crack paths in the tested specimens, the T-stress, out-of-plane Tz factor, local triaxiality parameter h and the governing parameter for the 3D-fields of the stresses and strains at the crack tip in the form of the In-integral are calculated as a function of the aspect ratio by finite element analysis to characterize the constraint effects along the semi-elliptical crack front. The plastic stress intensity factor approach is applied to the fatigue crack growth on the free surface, as well as at the deepest point of the semi-elliptical surface crack front, of the tested tension/bending plate and cruciform specimens. From the results, characteristics of the fatigue surface crack growth rate as a function of the loading conditions are established.

Stress Analysis of Suspended Pipe Partially Buried in Linear Elastic Soil

Based on the small deflection beam theory, bending equation with axial tension of suspended pipe partially buried in the linear elastic soil is established. And the corresponding boundary conditions are given according to the stress and deformation characteristics of suspended section and buried section. Then deflection equation for the suspended section is deduced. Afterwards, the stress and critical length of a suspended pipeline are calculated and analyzed. The results show that the tensile stress and bending stress on the endpoint of the suspended section meet the requirement of first strength theory and the critical suspended length is greater than the real suspended length, which is consistent with the actual situation. When the stiffness of soil tends to approach infinity, both the limit value of axial tension and endpoint bending moment agree well with the calculation results of fixed-fixed supported beam model.

Influence of fibre configuration on the mechanical behaviour of standard test specimens and full-scale beams made of flowable FRC

A large and unpredictable variation in the performance of flowable fibre-reinforced concrete limits its use in structural applications. The experimental programme presented in this paper aimed at evaluating the influence of fibre configuration (i.e. orientation and distribution) on the flexural behaviour of full-scale structural beams. The investigation focused on flowable fibre-reinforced concrete with high ductility provided by 2vol.% steel fibres with a length of 60mm. For this high fibre dosage, rigid interactions between fibres during casting can be expected. Computed Tomography scanning of the fibre concrete revealed large variations in fibre orientation and volume content. These inhomogeneities caused differences in the mechanical behaviour. The activation of cracks in locally weak areas proved to be decisive for the crack propagation and the load-carrying capacity of the beams.Notched specimens were assessed with three-point bending and uniaxial tension tests. The inhomogeneous configuration of the fibres predetermined the location of cracks in the full-scale structural beams and was identified as the main cause of the overestimation of structural behaviour using standard test methods.

The response of polymer optical fiber (POF) to bending and axial tension for the application of a POF sensor for automotive seat occupancy sensing

The automotive industry is a promising area for innovations in the field of polymer optical fiber (POF) sensors as the industry currently uses the POF mostly for data transmissions. Since an optical fiber sensor has a high bandwidth, is small in size, is lightweight, and is immune to electromagnetic interference, it offers higher performance than that of its electrical-based counterparts such as the strain gage, elastomeric bladder, and resistive sensor systems. This enhanced performance makes an optical fiber sensor a suitable material for sensing seat occupancy for improved safety features in automobiles. The overall goal of this research is to develop a textile-based optical fiber sensor for automotive seat occupancy with high accuracy and reproducibility. In this study, the bending and tensile loading responses of POF were investigated, where two perfluorinated (PF) graded index (GI) POFs with two different core/cladding diameters, 62.5/750 and 62.5/490 μm, were used. The bending loss and the light attenuation against the applied axial stress were measured by a photon counting optical time-domain reflectometer. The critical bending diameters were analyzed: Cytop-1 (62.5/750 μm) ≥ 38.10 mm, Cytop-2 (62.5/490 μm) ≥ 44.45 mm. Furthermore, the elastic sensitive strain regions (x), where the stress-induced loss was recoverable, of the POFs at a 76.2 mm gage length at a strain rate of 4 mm/min were determined: Cytop-1: 3% ≤ x ≤ 3.5%, Cytop-2: 3.1% ≤ x ≤ 3.3%. The Cytop-1 was found to be less sensitive to bending and to have greater elastic sensitive strain range relative to the Cytop-2. In this study, a theoretical approach of the PF GI POF behavior to bending and axial tension was provided. The results demonstrated the feasibility of POFs as optical fiber sensors for automotive seat occupancy sensing.

Predicted Fracture Behavior of Shaft Steels with Improved Corrosion Resistance

One of the crucial steps in the shaft design process is the optimal selection of the material. Two types of shaft steels with improved corrosion resistances, 1.4305 and 1.7225, were investigated experimentally and numerically in this paper in order to determine some of the material characteristics important for material selection in the engineering design process. Ultimate tensile strength and yield strength have been experimentally obtained, proving that steel 1.4305 has higher values of both. In addition, J-integral is numerically determined as a measure of crack driving force for finite element models of standardized fracture specimens (single-edge notched bend and disc compact tension). Obtained J values are plotted versus specimen crack growth size (Δa) for different specimen geometries (a/W). Higher resulting values of J-integral for steel 1.4305 as opposed to 1.7225 can be noted. Results can be useful as a fracture parameter in fracture toughness assessment, although this procedure differs from experimental analysis.

Compression and tension bending fatigue behavior of Ag nanowire network

Fatigue behavior of Ag nanowire network subjected to different degrees of compressive bending strain was investigated and compared against the results from tensile bending strain. Ag nanowire network under compression showed excellent reliability showing only a 6.0% increase in fractional resistance at 400,000 cycles, which is superior in comparison to that under tensile strain. The Ag nanowire network under compression was shown to cause buckling of the Ag nanowires, which then relaxed the elastic strain imposed on the Ag nanowire that led to enhanced reliability. The buckled nanowire, however, can cause strain localization especially with small radius of bending, thus causing the failure to occur within the length of individual nanowires unlike in the case of nanowire network under tensile strain that was shown to fail at the junctions with high stress concentrations.

Specific Adhesion of Giant Plasma Membrane Vesicles to Surface-Immobilized SIRPα by Membrane Reconstituted “Marker of Self” Signaling Protein CD47

Model membranes consisting of pure lipid components have clearly advanced the understanding of biological cell membranes. However, the reconstitution of membrane proteins into model lipid bilayers is not straightforward and requires specific strategies for each protein system. In contrast, membranes of living cells have a complex composition with a multitude of different lipid components, proteins and sugars. In this work, we show that membrane blebs derived from the plasma membrane of living cells, also called giant plasma membrane vesicles, can be used to study the interaction of the membrane proteins CD47 and SIRPα, which are involved in immune signaling. Membrane blebs are an interesting model because they exhibit the compositional heterogeneity of the plasma membrane but their morphological behavior can still be described by a few parameters such as bending rigidity, reduced volume and tension. Specifically, we study the interaction of CD47 reconstituted in blebs and surface-immobilized SIRPα. Using this model system we explore membrane-mediated cooperative binding effects under different biologically relevant conditions. We find that acidic environment decreases the binding affinity of membrane-reconstituted CD47 to SIRPα. Finally, we discuss implications for in-vitro cancer models. Financial support from the Deutsche Forschungsgemeinschaft (DFG) via the IRTG 1524 is gratefully acknowledged.

Elastic–plastic constraint parameter A for test specimens with thickness variation

AbstractThree‐dimensional elastic–plastic problems for a power‐law hardening material are solved using the finite element method. Distributions of the J‐integral in terms of the normalized elastic–plastic stress intensity factor and constraint parameter A along the crack front for varying the strain hardening exponent, specimen thickness and crack length are determined for edge cracked plate, centre cracked plate, three‐point bend and compact tension specimens. The second parameter A in three‐term elastic–plastic asymptotic expansion of the crack tip stress field is a measure of stress field deviation from the Hutchinson‐Rice‐Rosengren field and can be considered as a constraint parameter in elastic–plastic fracture. The loading levels cover conditions from small‐scale to large‐scale yielding. Results of finite element analyses show that the constraint parameter A significantly decreases when specimen thickness changes from 0.1 to 0.5 of the specimen width. Then, it has more or less stable value. Among four specimens, the highest constraint is demonstrated by the compact tension specimen that has the constraint parameter A lower than its small‐scale yielding value.

Experimental Study and Finite Element Analysis of Critical Stresses of Reinforced Thermoplastic Pipes Under Various Loads

In this paper, reinforced thermoplastic pipes (RTP) were studied under various loads. A total of five groups of specimens were designed to study the mechanical properties of RTPs under internal pressure, bending, a combination of internal pressure and bending moment, external pressure, and tension. This study obtained the bursting pressure of RTPs under internal pressure, the minimum bending radius under the bending moment, and the failure pressure under external pressure. At the same time, the mechanical properties of RTPs under various loads were analyzed using the finite element analysis. Analytical results agree well with the experimental ones. The finite element model established in this paper can be used for further research on the mechanical properties of RTPs.

Finite element analysis of UOE manufacturing process and its effect on mechanical behavior of offshore pipes

• We simulate the UOE forming process, using finite elements and an advanced plasticity model. • We present results for geometrical imperfections and anisotropy induced by the UOE forming process. • We investigate the effect of cold-forming on the performance of UOE pipes under external pressure, tension and bending. • We compare the structural performance of UOE pipes with the performance of seamless pipes. • We examine the efficiency of a simplified methodology for determining the structural capacity of a UOE pipe. Thick-walled steel pipes during their installation in deep-water are subjected to a combination of loading in terms of external pressure, bending and axial tension, which may trigger structural instability due to excessive pipe ovalization. The resistance of offshore pipes against this instability depends on imperfections and residual stresses due to the line pipe manufacturing process. The present study examines the effect of UOE line pipe manufacturing process on the structural response and resistance of offshore pipes during the installation process using advanced finite element simulation tools. The cold bending induced by the UOE process is simulated rigorously and, subsequently, the application of external pressure and structural loading (bending or axial force) is modeled, until structural instability is reached. A parametric analysis is conducted, focusing on the effects of line pipe expansion on the structural capacity of the pipe. The results show that there exists an optimum expansion at which the highest pressure capacity is achieved. The effect of the axial tension on the pressure capacity of the pipe is examined as well. The influence of the line pipe expansion on bending capacity in the presence of external pressure is also identified. Finally, a simplified methodology is employed, accounting for the material anisotropy induced by the manufacturing process, capable of determining the structural capacity of a UOE pipe in a simple and efficient manner with good accuracy, using more conventional modeling tools.

Innovative Applications of Steel Fibres in Concrete Flange of Composite Beam Subjected to Combined Negative Bending and High Axial Tension

The steel-concrete composite beam has become very popular these days and deterioration of the composite beam and its ultimate limit state are often reported in the subjection of combined negative bending and axial tension. Due to the presence of high axial loads, it was given a guideline in a previous research study by experimental investigation such that the failure modes were reinforcement fracture and shear connection failure in limiting the ultimate limit state of the composite beam subjected to combined negative bending and high axial tension rather than concrete failure. Thus, it is important to study in order to implement the strengthening methods with innovative material applications to overcome this problem. It was assumed that the application of steel fibres in the concrete flange will be an excellent contender owing to its in-service and mechanical properties, which is the hypothesis of this research. In order to evaluate this concept, the finite element (FE) models of a composite beam subjected to negative bending and high axial tension, and steel fibre reinforced concrete (SFRC) slab were developed with non-linear material components and validated with relevant experimental studies. Consequently, the plain concrete flange of composite beam was replaced by SFRC flange and studied the failure behaviour of the composite beam subjected to combined negative bending and high axial tension. It was predicted that an improvement in the ultimate limit state and in initial cracking load due to the postponing the failure modes, which are extensively discussed and suggested as it will be a strengthening method of the concrete flange on the composite beam in such cases.

Innovative Applications of Steel Fibres on Composite Beam with Profiled Plain Concrete Flange Subjected to Combined Negative Bending and Axial Tension

The introduction of profiled steel sheet is a mature application nowadays on composite construction. A major concern is that there should be an improvement in the degree of shear connection in the negative bending region nearby internal supports due to the unfavourable failure criteria of concrete such that additional shear studs are wanted. Further, such shear studs may be possible to be functioning in insufficient spaces of the troughs owing to the profiled flange. In addition, axial tension will be induced in the steel section based on various cases, which will form an unfavourable failure phenomenon by induced excessive slip. In order to represent all of these criteria, the concern of profiled steel fibre reinforced concrete (SFRC) flange instead of plain concrete flange against the forming of concrete cracks, which results a potential application in postponing the failure mode, is executed and discussed in this paper. The finite element (FE) models were developed to each component in various cases with non-linear material behaviours and validated against the experimental analysis available. It was found that the application of steel fibres in the profiled plain concrete flange can improve the performance of the composite beam subjected to combined negative bending and negative bending such that it would not only postpone the cracking of concrete but also control the propagation of the cracks.