Tensile Bending Stress Research Articles

P-10: Excellent Mechanical Bending Stability of Flexible a-IGZO TFT by Dual Gate Dual Sweep Using TCAD Simulation

We report mechanical bending effect on electrical performance of flexible amorphous-indium-gallium-zinc-oxide (a-IGZO) thin film transistors (TFTs) using TCAD simulation. Tensile bending stress for a single gate (SG) TFT exhibits higher electron concentration and lower resistivity along the channel than those of flat and compressive geometries. The dual gate (DG) TFT with dual gate sweep (DS) shows increased conductivity and improved bending stability. These findings are an important step toward the realization of high performance DG flexible TFTs for future display applications.

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.

The Effect of Radiation on Mechanical Properties of Parts Made of Polymer Composites

The article deals by the application area of radiation crosslinking of plastics, which follows after the injection moulding. The main objective of the presented article is the research of influence irradiation dosage on mechanical properties of materials: PP unfilled and PP filled by 25% of glass fibres. Mechanical properties (tensile strength, modulus, bending stress and impact strength by Charpy test) were examined in dependence on absorbed dose of the β electron radiation on various conditions and were compared with non-irradiated samples.

7075-T6 aluminium alloy exfoliation corrosion sensitivity and electrochemical impedance spectroscopy under stress

Exfoliation corrosion susceptibility under tensile-bending stress of 7075-T6 aluminium alloy was tested with a self-made tri-fulcrums loading fixture. The test results of both microscopic characterisation and electrochemical impedance spectroscopy indicate that the alloy's exfoliation corrosion susceptibility in exfoliation corrosion solution increases evidently for tensile-bending stress. The electrochemical impedance spectroscopy of the loaded sample soaked for 12 hours manifests double capacitance arcs as the mark of propagated exfoliation corrosion, which takes 24 hours for the unloaded one to reach the same results. Results analysed by equivalent circuit model also prove the accelerating effect of tensile-bending stress on exfoliation corrosion susceptibility.

Cracking resistance of Cr3C2–NiCr and WC–Cr3C2–Ni thermally sprayed coatings under tensile bending stress

The cracking behaviour of Cr3C2–25(Ni20Cr) and WC–20Cr3C2–7Ni thermally sprayed coatings during tensile load in 3-point bending tests was studied by Acoustic Emission (AE) monitoring and microstructure post-analysis. The AE monitoring reveals a superior resistance against cracking in the WC–Cr3C2–Ni coatings compared to Cr3C2–NiCr. The incorporation of tungsten carbides beneficially affects the residual stress state of the coatings and has an impact on the detailed fracture mode. The results hold for both as-sprayed as well as ground and polished coatings.

Optimal Zone II flexor tenorraphy

Optimal Zone II flexor tenorraphy

Effect of Island Configuration and Neutral Axis Location for Mechanical Bending Strain on a-IGZO Thin Film Transistors

The effect of electromechanical and mechanical strain was studied on amorphous indium-gallium-zinc-oxide (a-IGZO) thin film transistor regarding to the structural design of the device as well as the location from neutral plane (N.P) for bending stress. Here we show a highly reliable bending feature of the island structured (IS) device and its backplane against the mechanical strain after being subjected to an extreme tensile cyclic bending stress. The IS TFTs fabricated on polyimide (PI) substrate exhibit an pronounced bendability for an cyclic bending of 100,000 cycles with varying radii to a radius less than 2 mm with the electro-mechanical integrity. The onset of crack strain also closely corresponds to that of the electrical degradation of the device. The backplane array composed of IS TFTs clearly reveals that the island configuration remarkably reduce the bending stress accumulation on the sheets of inorganic stacked layers along to the uniaxial on plastic substrate.

Durability Design of Marine Concrete Structure Considering the Influence of Load

In this paper, based on accelerated testing indoors, under the action of bending tensile stress on a marine high-performance concrete chloride ion diffusion coefficient, the results show that: Subjected to bend under the action of tensile stress and do not withstand the test piece chloride diffusion coefficient increases with increasing stress levels, different tensile stress and does not bear the stress of the concrete chloride ion diffusion coefficient ratio (Dη/D0) exponential relationship with the stress level (η). In addition, addition, for a domestic Bridge, preliminary design to determine typical parameters of components and their environment is proposed to consider the durability of concrete structure load control index calculation method, to establish a "design life - chloride ion diffusion coefficient controlled targets" the correspondence between, for similar projects designed to provide a reference durability.

Bending Characteristics of Foldable Touch Display Panel with a Protection Structure Design

The study proposes and demonstrates an enhancement of a touch display panel (TDP) through a polymer-based protection structure to achieve higher bendability and reliability. The bending performance of the TDP without or with the protection structure designs is addressed using three-dimensional geometry-nonlinear finite element analysis and mechanical testing. The elastic properties of the components in the TDP structure are derived from nanoindentation and uniaxial tensile/compressive testing. The calculated results are compared with each other and also against the experimental bending fatigue test data. At last, a design guideline and optimal factor setting for enhanced bending performance are sought through parametric FE analysis and Taguchi experimental design, respectively. The optimal design is compared with the original in terms of bending stress. The simulation results show that bending would create significant tensile and compressive bending stresses on the indium tin oxide/dielectric layers, which are the main cause of several commonly observed failures, such as thin film cracking and delamination, in a thin rigid film coating on a thick compliant substrate. It also turns out that a substrate with a lower stiffness has a better mechanical stability against bending stress.

Effect of head wear and lateral forces on underhead radius crack propagation

This paper investigated the effect of rail head wear (HW) and lateral forces on underhead radius stress conditions and resulting stress intensity factors (SIFs) of a long transverse crack. The occurrence of tension spikes at the underhead radius of the rail as a result of localised vertical and lateral bending of the head-on-web was significantly exacerbated with increasing rail HW. The extended finite element method (X-FEM) modelling, which had previously been validated by comparison with in-track measurements to verify the prediction of tension spikes, was used to model a single rail on discrete elastic foundations. SIFs along the crack front were parametrically evaluated in terms of changes in the contact patch offset (CPO), the ( L/ V) ratio of lateral ( L) to vertical ( V) loads, the rail HW, and crack size and shape. The X-FEM results revealed that for a long transverse crack, extending the crack length to the underhead radius position results in higher SIFs across the underhead radius as a result of tensile bending stresses. These higher SIFs can contribute to a massively higher crack growth rate at this location, as was evidenced by the crack growth morphology at the underhead radius.

Mechanical analysis on the cylinder-crown integrated hydraulic press with a hemispherical cylinder

As a new press, cylinder-crown integrated hydraulic press (CCIHP) is analyzed firstly in this paper. The hydraulic cylinder consists of a hemispherical shell, which also functions as a main proportion of press crown. Compared with the conventional hydraulic press which has a hydraulic cylinder mounted in the press crown, the structure and force distribution of CCIHP are significantly different. First, the section modulus of the hemispherical crown is much larger than that of the conventional rectangle crown because the hydraulic cylinder and press crown are manufactured into a solid part and have a higher geometry centroid. Therefore, the hemispherical crown has lower tensile bending stress and a higher safety factor from the strength point of view when the same bending moment is applied. Second, under the conditions of same value in terms of the allowable stress, internal pressure and internal radius, the wall thickness of hemispherical hydraulic cylinder could be much thinner than that of the conventional hydraulic cylinder. Both of the reasons mentioned above can result in a weight reduction of the press. Also, the cylinder and the press crown can be reinforced by each another, as a result, the material strength capacity is better utilized. As a prototype, the 6300 kN CCIHP with hemispherical hydraulic cylinder, which is the first one of this kind press designed and manufactured by Harbin Institute of Technology (HIT) is introduced in this paper. Finite element analysis for CCIHP has shown that both the stress and displacements on the press during the loading process are allowable, even if eccentric force is loaded. Finally the priority application range of CCIHP has also been proposed.

Dynamic Response of Thin-Walled Structures to Thermal Loadings and Random Acoustic Excitations

Hypersonic aircrafts are facing increasingly severe aerodynamic heating, noise and so on, which will lead to nonlinear vibration characteristics for thin-walled structures of hypersonic aircrafts. Considering the influence of thermo-acoustic loadings, finite element formulation of simply supported plate under combined thermo-acoustic loadings are founded, and vibration characteristics of simply supported plate under thermal loadings with temperature gradient and random acoustic loadings are investigated. According to finite element numerical method, modal frequencies, critical thermal buckling temperature difference, dynamic stress response of simply supported plates with temperature gradient under combined thermo-acoustic loadings were calculated before and after thermal buckling. The results show that three types of motion: random vibrations around initial equilibrium position in pre-buckling region, snap-through oscillations between two post-buckling equilibrium positions, nonlinear vibrations around one of the two post-buckling equilibrium position, and The RMS of nodes for different locations of the simply plate are obtained in pre-buckling post-buckling region, and it is shown that different interaction of tensile bend stress, compressive stress and compressive thermal stress lead to different RMS trends.

Dome Window and Mount Design for a 5 MWth Solar Receiver

Large windows are being evaluated for use in high temperature concentrated solar receivers to reduce radiative and convective losses, maintain a differential pressure, and separate reactants from ambient air in receivers for chemical processing. The design of a 1.7 meter diameter fused silica dome window is evaluated for its ability to maintain acceptable stresses when exposed to pressure differentials and large heat loads from solar irradiation and re-radiation from inside the receiver. The dome must be ableto withstand the operational pressure differential of 0.5MPa where the efficiency of the solar receiver combined with a recuperated gas turbine is maximized, and glass temperatures upwards to 800°C may be observed. Brittle materials like glass need the tensile stresses to be reduced to maximize the reliability of the dome window. However, glass does not possess a characteristic strength and it is dependent on the flaw size. Careful attention to the dome mount must be taken to minimize tensile bending stresses that can cause a catastrophic or rapid failure while maintaining an environmental seal.The Weibull failure probability method is used to arrive at a projected lifetime of the window under a constant state of stress. This stress is used to determine the maximum design stresses allowed during operation of the solar receiver. Window heat fluxes from a Monte Carlo Ray Trace of the heliostat field and receiver re-radiation is utilized to couple the thermal mechanical effects of the window and its mount. A finite element analysis (FEA) is presented evaluating the stresses when considering the heat absorption in the window from transmitted light and re-radiation from within the solar receiver, combined with the applied pressure differential between the solar receiver and atmospheric conditions. The preliminary design of the window shape, thickness, and mounting strategy is presented.

Theoretical and Experimental Studies on Stresses in Vacuum Glazing due to Temperature Difference

The existence of a temperature difference across a vacuum glazing causes dimensional differences between the hot and cold glass sheets, with associated mechanical stresses and bending. In order to understand the distribution characteristics of the stresses and deformation in vacuum glazing due to temperature difference, in this work, the mechanical models were established and the calculation formula of the shear stress in the edge seal and bending tensile stress on the surface of the two glass sheets of the vacuum glazing were given. A test device was designed and the maximum tensile stresses and deflection of the vacuum glazing with various temperature difference were tested by experimental, it was shown that they are identical between the experiments and the theories.

Cracking Mechanism and Strengthen Method of Reinforced Concrete Hammerhead Piers

This paper indicates cracking mechanism and strengthening method of reinfoced concrete hammerhead piers. A field investigation phase has been undertaken in conjunction with analytical studies to model the cracking process. It is shown that the front cracks in the pier cap developed because the bending tensile stress far exceeds the tensile strength, while the side crack caused by none bursting reinforcement. Based on the analysis results, an internally prestressing approach is provided, and the retrofitting effect is verified by finite element analysis. Strengthening with internally prestressed tendons of bridge pier cap is proven to be a reliable and relatively easy-to-install technique.

The long-term topographic response of a continent adjacent to a hyperextended margin: A case study from Scandinavia

We present data that link Scandinavia’s passive-margin domains under a unified system invoking isostatically driven, postextension phase vertical adjustments to severe crustal thinning. Topographic and geological data indicate that the relative location of the first landward occurrence of total crustal embrittlement or deformation coupling—the Taper Break—controlled and continues to control Scandinavia’s post-thinning geomorphic evolution. Formed during Late Jurassic or Early Cretaceous thinning, yet marked today by seismicity, the Taper Break closely approximates the boundary between (1) less-stretched lithosphere that increases in rigidity both toward land and through postrift time, and (2) the highly attenuated, pervasively faulted, permanently weakened lithosphere of the distal margin. Following the stretching, thinning, and exhumation phases proposed by other workers, an accommodation phase is warranted. Commencing during “sag” basin time and continuing today, it is probably driven by thermal cooling and mass transfer from the escarpment to the basins offshore. The accommodation phase does not entirely coincide with the traditional postrift phase as the former may contain the latter. During accommodation, the original synrift escarpments can be eroded to very low base levels. Sharply tapered margin segments can undergo subsequent rejuvenation by out-of-sequence normal faulting and footwall uplift, probably in response to tensile bending stresses engendered by lithospheric-scale flexure. Accommodation-phase uplift at passive margins is the inexorable and penultimate phase of hyperextension, and may perhaps be followed by the onset of subduction localized by the weakened lithosphere of the distal margin and the ocean-continent transition.

Experimental Study Of The Interaction Of Corrosion Damage And Out-Of-Circularity In The Collapse Of Submarine Pressure Hulls - Technical Note

The effect of corrosion damage on overall collapse strength of submarine pressure hulls was studied experimentally. Ring-stiffened cylinders were machined from aluminium tubing and loaded to collapse under external pressure. In selected specimens, some of the outer shell material was machined away in large single patches, representing general corrosion. Other specimens had many smaller patches, representing corrosion pitting from the outside of the hull, followed by grinding. Large-amplitude out-of-circularity (OOC) was introduced by mechanically deforming selected cylinders. Clusters of artificial corrosion pits were found to have approximately the same effect on collapse pressure as equal-depth general corrosion covering the same region of plating. General corrosion was found to be most severe when it was “in-phase” with OOC, since, during pressure loading, high compressive stresses resulting from corrosion were compounded by compressive bending stresses associated with OOC, and furthermore, the corrosion tended to increase the geometric imperfection itself. On the other hand, out-of-phase corrosion reduced the effect of OOC, while at the same time the thinning-associated compressive stresses were counteracted by local tensile bending stresses associated with OOC, so that strength reductions were correspondingly smaller. Overall collapse pressures for corroded specimens were reduced by, on average, 0.85% for each 1% of shell thinning. That result is based on a linear approximation of the nonlinear relationship between thinning and collapse pressure. The linear trend-line, which was used to account for the experimental scatter, is based on specimens with 13 to 27% shell thinning, and with a variety of corrosion areas and OOC amplitudes.

Role of elastic bending stress on magnetism of a manganite thin film studied by polarized neutron reflectometry

We measured the magnetization depth profile of a (La1-xPrx)1-yCayMnO3 (x = 0.60\pm0.04, y = 0.20\pm0.03) film as a function of applied bending stress using polarized neutron reflectometry. From these measurements we obtained a coupling coefficient relating strain to the depth dependent magnetization. We found application of compressive (tensile) bending stress along the magnetic easy axis increases (decreases) the magnetization of the film.

Stability Analysis of Rock Slopes Against Block-Flexure Toppling Failure

Block-flexure is the most common type of toppling failure in rock slopes. In this case, some rock blocks fail due to tensile bending stresses and some overturn under their own weights. In this paper, first, a literature review of toppling failures is summarized. Then, a theoretical model is proposed for rock slopes with a potential for block-flexure toppling instability. Next, a new analytical approach is presented for the stability analysis of such slopes. Finally, a special computer code is developed for a quick stability assessment of the failures based on the proposed method. This code receives the rock slope parameters from the user as the input data and predicts its stability, along with the corresponding factor of safety against the failure, as the output. In addition, two case studies are used for practical verification of the proposed approach and the corresponding computer code as well.

Finite element modelling of the rail gauge corner and underhead radius stresses under heavy axle load conditions

Highly localized stresses generated at the gauge corner of the outer rail cause fatigue cracking. The longitudinal bending stresses in the rail underhead radius position are of special interest, as tension spikes have been identified at this location during in-track measurements under high axle load conditions. The tension spike is a result of vertical and lateral head bending on the web. This effect is highly localized and is additional to the stresses generated due to vertical and lateral bending of the whole rail profile (the so-called global bending). This study examined contact and bending stresses by modelling the rail on a discrete foundation using finite elements and by considering the loading to be a fully slipping elliptical Hertzian contact patch. The analysis revealed that the tensile longitudinal stress was highly dependent on several service conditions: the contact patch offset from the rail centreline, the ratio of lateral ( L) to vertical ( V) loads, the direction of lateral traction, foundation stiffness and seasonal temperature variations. The tension spike increases, and the depth below the contact surface at which the stresses become tensile reduces, as the contact patch offset and/or the L/ V ratio increases. Both these enhance the tendency for rolling contact fatigue cracks to turn downwards and become transverse defects. This is because an increase in tensile bending stresses together with both residual and thermally induced stresses can facilitate cracks to turn perpendicular to the tensile stresses once they reach a critical length. Shear traction towards the gauge corner was found to be the most damaging phenomenon.