Tangential Deformation Research Articles

Thermo-mechanical buckling analysis of FG-GNPs reinforced composites sandwich microplates using a trigonometric four-variable shear deformation theory

The current study is aimed to investigate the thermo-mechanical buckling responses of the sandwich microplate with Graphene nanoplatelets (GNPs)-reinforced Epoxy core fully bonded to single-walled carbon nanotubes (SWCNTs)-reinforced piezoelectric patches. The face sheets were exposed to the electric field and the microplate was assumed to locate on the Pasternak elastic substrate. The GNPs and SWCNTs were dispersed throughout the core and face thickness according to some specific functions. To consider the shear deformation effect, tangential shear deformation theory (TSDT), as a trigonometric higher-order theory, was used. The size effects were also included through applying and the modified strain gradient theory (MSGT). The virtual displacement principle was utilized to derive the governing equations and then by employing an analytical method, they were solved. The validity of the results was confirmed by comparing the results for simpler state with previously published ones. A parametric study is provided to observe behavior of the microstructure in different conditions. It was observed that GNPs and CNTs dispersion patterns play an important role in the microplate buckling behavior, as well as temperature variations. The outcomes of this work may help to manufacture more efficient engineering smart structures, such as micro/nanoelectromechanical systems.

Investigation of the dynamic stability of bending-torsional deformations of the pipeline

Nonlinear mathematical models are proposed that describe the dynamics of a pipeline with a fluid flowing in it: a) the model of bending-torsional vibrations with two degrees of freedom; b) the model describing flexural-torsional vibrations taking into account the nonlinearity of the bending moment and centrifugal force; c) the model that takes into account joint longitudinal, bending (transverse) and torsional vibrations. All proposed models are described by nonlinear partial differential equations for unknown strain functions. To describe the dynamics of a pipeline, the nonlinear theory of a rigid deformable body is used, which takes into account the transverse, tangential and longitudinal deformations of the pipeline. The dynamic stability of bending-torsional and longitudinal-flexural-torsional vibrations of the pipeline is investigated. The definitions of the stability of a deformable body adopted in this work correspond to the Lyapunov concept of stability of dynamical systems. The problem of studying dynamic stability, namely, stability according to initial data, is formulated as follows: at what values of the parameters characterizing the gas-body system, small deviations of the body from the equilibrium position at the initial moment of time will correspond to small deviations and at any moment of time. For the proposed models, positive definite functionals of the Lyapunov type are constructed, on the basis of which the dynamic stability of the pipeline is investigated. Sufficient stability conditions are obtained that impose restrictions on the parameters of a mechanical system.

Виявлення дефектів складання осердя статора потужного турбогенератора

In this paper technology and device for automated detection of the location and size of defects in the stator core of a powerful turbine generator (TG) during assembly at the manufacturing plant is proposed. The core is assembled and pressed in a vertical position in separate parts and at each stage of assembly it is necessary to find places with a weakened solidity. Existing control methods, including automatic ones, will not allow quality control. Using the proposed technology, places in the core with weakened solidity can be detected. In this case, measurements of the specific pressing pressure are carried out at certain points of the end surface of the core, where special control samples from an easily deformable material are installed. The device is implemented as a ring installed on the end surface of the core, in which N cells with control samples are installed. During pressing, the thickness of the samples decreases and the greatest decrease in the thickness of the sample, caused by the corresponding highest specific pressure, corresponds to the smallest defect, and vice versa. Flat metal membrane with a rigid center as a primary pressure transducer has been proposed to use, on which an optical fiber with Bragg gratings is fixed, one of which measures the tangential relative deformation in the membrane, and the second serves for thermal compensation. In paper it has been shown that tangential deformation in a flat membrane depends on the specific pressing pressure. The characteristics of the converter are calculated. The measurement results are processed using an interrogator and a personal computer. The use of the device makes it possible to increase labor productivity when monitoring the core, as well as more reliably diagnose its defects with their subsequent elimination, which ultimately will increase the reliability of the TG and its durability.

Stresses and deformations of an eccentric cylindrical cam during hydro-joining

The stresses and deformations of an eccentric cylindrical cam during the process of hydro-joining have been calculated in orthogonal curvilinear coordinates according to the mechanical model of the cam and governing equations in terms of appropriate complex potentials with suitable boundary conditions. The radial and shearing stress coefficients determined for an example cam are far less than that of the tangential stress during hydro-joining. The tangential stress coefficient of the outer surface of the cam is greater than that of the internal surface when the polar angle exceeds a particular value. The position of the maximum value of the radial stress coefficient is located on the internal surface of the cam, and the maximum shear stress coefficient is located between the inside and outside surfaces of the cam. The cam deformations on the internal and external surfaces under internal pressure respectively attain maximum values at particular angles. The maximum values of the radial and y-directional deformations are located at the position of the minimum wall thickness. The radial deformations determined for an example cam are far larger that the tangential deformations during hydro-joining. The errors between the theoretical and numerical solutions for the tangential stress and the y-directional deformation are both very small.

Piercing of a Billet in a Mill with Guide Disks

The piercing of billets in a helical rolling mill with guide disks is considered. The resulting sleeve sizes are shown to differ significantly from the sizes of the sleeves produced using other piercing schemes because of severe tangential deformation. As a result, the energy–force parameters of piercing are different and the results of their calculations according to the generally accepted empirical dependences are inadequate. The results of piercing simulation with the QFORM 3D software package are presented.

Thermochronology of the Angara–Vitim Granitoid Batholith, Transbaikalia, Russia

We reconstructed the history of the Angara–Vitim batholith (AVB), characterized by the formation of huge volumes of granitic magma using thermochronological analysis (40Ar/39Ar, U/Pb) and math testing selected age milestones on the basis of the model crystallization differentiation and dynamics of heat and mass transfer in a magmatic chamber. The consolidation time of the granite melt is estimated to be in the range of 320–290 Ma. Events with age are distinguished based on the presence of isotope dating clusters T1 = 245 ± 1 Ma; T2 = 212 ± 1 Ma; T3 = 156 ± 1 Ma; T4 = 125 ± 2 Ma. The thermal history of samples corresponding to the modern erosion level immediately imposes strict restrictions on the history of consolidation and cooling for rocks corresponding to the deep (>20 km) levels of the magmatic chamber. Calculations show that the lifetime of the residual melt at the deep levels of the magmatic chamber of the AVB can reach 100 Ma. Events with age 245 ± 1, 212 ± 1, 156 ± 1, 125 ± 2 Ma reflect the gradual transformation of the “semi-frozen granite layer” and the discrete nature of its tectonic exposure to the upper level of the Earth’s crust under the influence of tangential elastic deformations caused by the pulsating manifestation of intraplate mantle magmatism within the Siberian platform and its folded frame. The final stage of AVB tectonic exposure to the Earth’s surface (as a solid body) occurred from 60 Ma to the present time, reflecting the process of origin and development of the Baikal rift system.

FLEXURAL RIGIDITY OF MULTILAYER PLATES

The flexural rigidity of a thin elastic multilayer plate with transversely isotropic layers is considered. If the rigidity of the layers is very different, the classical model based on the hypothesis of a straight normal is not applicable and the effect of lateral shear must be taken into account. Two models for taking into account the effect of transverse shear for a multilayer plate are compared. The first of them, based on the distribution of tangential deformations over the thickness of the plate, was proposed in the work of E. I. Grigolyuk and G. M. Kulikov in 1988. The second model uses an asymptotic expansion of the solution of three-dimensional equations of elasticity theory in powers of a small thin-walled parameter. The errors of the models are estimated by comparison with the exact solution of the three-dimensional test problem.

A numerical approach for fluid deformable surfaces

Abstract

Topology optimization of elastic contact problems with friction using efficient adjoint sensitivity analysis with load increment reduction

This work presents a topology optimization method for the stiffness maximization design of elastic structures with frictional contact. The friction behavior is assumed to be governed by the Coulomb friction law regularized in analogy with the perfect elasto-plastic theory. To facilitate efficient adjoint sensitivity analysis, two load increment reduction (LIR) rules are proposed for sticking friction and pure sliding friction, and are validated by theoretical proof and numerical verification. The first rule is that any load increment whose set of sticking contact node pairs contains that of the load increment after can be skipped in the adjoint sensitivity analysis without influencing the final calculated sensitivities. The second one is that all load increments before the load increment in pure sliding friction can also be skipped. The implemented topology optimization procedure is validated by numerical examples. It is found that only the final load increment is needed in the overwhelming majority of iterations for all the tested cases based on the LIR rules. The computational burden of sensitivity analysis is thereby greatly reduced. Results also show that the optimized compliance generally decreases as the friction coefficient increases because the friction behavior helps to resist tangential deformations at the contact interface.

Initial research of changes in mechanical properties of polymer-graphene composite with use of Digital Image Correlation

The problem of the possibility of using digital image correlation to assess changes in the mechanical properties of a polymer composite with the addition of graphene (1% by weight) in the form of flakes was taken up in the paper. Samples for uniaxial tensile testing were produced by selective laser sintering from polyamide powder particles and multi-flake graphene. In the tests carried out using the three-camera system, a variable strain distribution was recorded in the heterogenic PA-G composite material. Maps developed in the evaluation process – in particular, tangential deformations – allowed to conclude the impact of axial load on PA-G behaviour in time in the area of the polymer matrix, graphene agglomerates, and their interfaces. The research showed that the digital image correlation technique is a perfect complement to traditional mechanical tests when determining the properties of new heterogeneous composites, in particular, polyamide-graphene composite. Real-time observation of changes in the material map allows for a detailed analyzes of complex micromechanical aspects.

Analysis on cooperative working performance of curtain wall glass and steel hanging columns

The curtain wall of Xi’an Silk Road International Conference Center is a large-span combined steel column supported glass curtain wall system. The curtain wall glass is directly installed on the steel hanging columns of the external suspension structure, and there are no curtain wall hanging columns that are independent of the main structure. The vertical, tangential and radial deformation of the steel hanging columns under service load may lead to vertical shear, in-plane extrusion, in-plane sliding and out of plane bending of the curtain glass. Therefore, finite element model of curtain wall glass was established using the finite element program ABAQUS. Considering the four possible failure modes of the curtain glass, the collaborative working performance of the curtain wall glass under the most unfavourable deformation conditions of steel hanging columns was analyzed.

The effect of tactile augmentation on manipulation and grip force control during force-field adaptation

BackgroundWhen exposed to a novel dynamic perturbation, participants adapt by changing their movements’ dynamics. This adaptation is achieved by constructing an internal representation of the perturbation, which allows for applying forces that compensate for the novel external conditions. To form an internal representation, the sensorimotor system gathers and integrates sensory inputs, including kinesthetic and tactile information about the external load. The relative contribution of the kinesthetic and tactile information in force-field adaptation is poorly understood.MethodsIn this study, we set out to establish the effect of augmented tactile information on adaptation to force-field. Two groups of participants received a velocity-dependent tangential skin deformation from a custom-built skin-stretch device together with a velocity-dependent force-field from a kinesthetic haptic device. One group experienced a skin deformation in the same direction of the force, and the other in the opposite direction. A third group received only the velocity-dependent force-field.ResultsWe found that adding a skin deformation did not affect the kinematics of the movement during adaptation. However, participants who received skin deformation in the opposite direction adapted their manipulation forces faster and to a greater extent than those who received skin deformation in the same direction of the force. In addition, we found that skin deformation in the same direction to the force-field caused an increase in the applied grip-force per amount of load force, both in response and in anticipation of the stretch, compared to the other two groups.ConclusionsAugmented tactile information affects the internal representations for the control of manipulation and grip forces, and these internal representations are likely updated via distinct mechanisms. We discuss the implications of these results for assistive and rehabilitation devices.

Analytical investigation of the friction reduction performance of longitudinal vibration based on the modified elastoplastic contact model

An analytical friction model considering material properties and surface topography is established to predict the friction reduction performance of longitudinal vibration, and a set of closed-form solutions are derived and verified. A parameter study is conducted based on the model. Results show that the vibration parameters, normal load, surface morphology, and material properties have significant influences on the friction reduction effect. The friction reduction mechanism is mainly attributed to the changes in the magnitude and direction of asperities tangential deformation. The analytical model can efficiently and accurately calculate the contact parameters and instantaneous friction force of rough contact surfaces, and provide theoretical guidance for the rational utilization of longitudinal vibration to achieve better friction reduction performance in mechanical systems.

Chiral metamaterial predicted by granular micromechanics: verified with 1D example synthesized using additive manufacturing

Granular micromechanics approach (GMA) provides a predictive theory for granular material behavior by connecting the grain-scale interactions to continuum models. Here, we have used GMA to predict the closed-form expressions for elastic constants of macroscale chiral granular metamaterial. It is shown that for macroscale chirality, the grain-pair interactions must include coupling between normal and tangential deformations. We have designed such a grain-pair connection for physical realization and quantified with FE model. The verification of the prediction is then performed using a physical model of 1D bead string obtained by 3D printing. The behavior is also verified using a discrete model of 1D bead string.

Equivalence of a Constrained Cosserat Theory and Antman’s Special Cosserat Theory of a Rod

The general nonlinear Cosserat theory of a rod allows for tangential shear deformation, axial extension and a deformable cross-section. Simplified equations are obtained by introducing kinematic constraints and associated constraint responses which force the cross-section to remain rigid. The equations of motion of this constrained Cosserat rod are shown to be equivalent to those of Antman’s nonlinear special Cosserat theory of a rod. Strain measures motivated by the general Cosserat rod theory are used to develop explicit hyperelastic constitutive equations for the force and moment applied to the rod’s ends.

ВИЗНАЧЕННЯ ОСНОВНИХ КРИТЕРІЇВ ЕФЕКТИВНОЇ РОБОТИ ДЕГАЗАЦІЙНОЇ СВЕРДЛОВИНИ

Purpose. Research and substantiation of the main criteria for sustainable and efficient operation of degassing wells. Methodology. In the work, the method of mine observations was used to study the geomechanical state of the rock mass around the development workings and the operating long working face. Results. The directions and magnitudes of tangential deformations in the rock mass following the movement of the working face are investigated to ensure the safety of the section of the degassing well. It has been found that with an inclined wellbore, the diameter in the direction of inclination increases inversely to the value of the cosine of the inclination angle. It is justified to ensure the safety of the well section in the area of ​​intense tangential deformations of the massif and its efficiency in general, by choosing a sufficient diameter of the well degassing and its angle of inclination to the bedding plane. Originality. The main four criteria of stable and efficient operation of the degassing well have been determined and substantiated, which take into account the outrageous deformations of the massif, the limiting level of rock pressure, the value of concentrated displacement and radial displacement of rocks around the development workings from which degassing wells were drilled. It was found that with a decrease in the diameter of the borehole degassing section by an amount not exceeding the borehole radius, the local aerodynamic resistance in the narrowing section increases insignificantly. However, the further section of the wellbore increases its aerodynamic drag abruptly, and the well flow rate decreases many times. Practical value. Based on the formulated criteria and the identified factors, it is planned to develop measures to ensure the stability of the degassing wellbore and the efficiency of its functioning. Key words: degassing; risk; well deformation.

Researching rolling resistance of the wheeled forestry tractor at skidding

Off-road performance improvement remains one of the main problems in designing wheeled dragging and forestry tractors. Improvement of off-road performance of the dragging and forestry tractors is closely related to the general problem of wheeled vehicles’ off-road performance, however it features a number of specific aspects which require specialized research to be made.During tree skidding by a wheeled tractor, vertical load on a double-reduction axle greatly changes that is linked to additional load by a roundwood bundle and redistributed in-motion load. The above in-motion redistribution of load and driving moments along the axles greatly affects the vehicle’s off-road performance. While skidding, the increased load on a wheel leads to increased specific pressure, track depth and rolling resistance.This work employs simplified tire calculation model used as a base to determine relationship between load and deformation. Calculation is made successively for each elementary tire section that allows for finding diagram of pressure distribution in the contact longitudinal plane and researching rolling resistance related to rutting and hysteresis losses in the tire material. Further experimental research of the driving wheel and wheel system motion allowed for elaborated theoretical analysis and helped to justify parameters the forestry tractor wheels.The following tasks were set during this work:1. To make efforts to elaborate approximated method for estimating relative elongation of the rolling resistance depending on wheel parameters, vertical load and air pressure. The method is based on calculation of contact pressure distribution on the basis of simplified tire model2. To conduct experimental research of rolling resistance for one wheel and wheel set of a tractor in the leading movement mode with due regard to tire tangential deformation.3. To study aspects of a process of rolling resistance of a forestry tractor during tree skidding in summer time. To run comparative draw tests of a forestry tractor equipped with tires of variable size.4. To find out possibilities to reduce rolling resistance basing on theoretical and experimental researches.

Quasi-3D tangential shear deformation theory for size-dependent free vibration analysis of three-layered FG porous micro rectangular plate integrated by nano-composite faces in hygrothermal environment

A quasi-3D tangential shear deformation theory is employed to analyze free vibration behavior of a three-layered FG porous micro plate which is located between two polymeric nano-composite layers. The structure is in a hygrothermal environment and Lorentz force is applied to it. Also, it rests on an elastic foundation which is modeled by Pasternak type. The properties of core and faces are changed following the given functions and also are temperature-dependent. Hamilton’s principle and Navier’s method are employed to extract and solve motion equations, respectively. Effect of the most prominent parameters is considered and discussed in detail.

Experimental Measurement of In-Plane Rolling Nonpneumatic Tire Vibrations Using High-Speed Imaging

ABSTRACT This article presents a novel experimental technique for measuring in-plane deformations and vibration modes of a rotating nonpneumatic tire subjected to obstacle impacts. The tire was mounted on a modified quarter-car test rig, which was built around one of the drums of a 500-horse power chassis dynamometer at Clemson University's International Center for Automotive Research. A series of experiments were conducted using a high-speed camera to capture the event of the rotating tire coming into contact with a cleat attached to the surface of the drum. The resulting video was processed using a two-dimensional digital image correlation algorithm to obtain in-plane radial and tangential deformation fields of the tire. The dynamic mode decomposition algorithm was implemented on the deformation fields to extract the dominant frequencies that were excited in the tire upon contact with the cleat. It was observed that the deformations and the modal frequencies estimated using this method were within a reasonable range of expected values. In general, the results indicate that the method used in this study can be a useful tool in measuring in-plane deformations of rolling tires without the need for additional sensors and wiring.

Assessment of the seismic capacity of tall wall buildings using nonlinear finite element modeling

Two existing RC shear wall buildings of 17 and 26 stories were analyzed using fully nonlinear finite element models, i.e., models that include nonlinear material behavior and geometric nonlinearities. The buildings are located in Santiago, Chile and are representative of Chilean residential buildings in the sense that they have a large number of shear walls. The buildings withstood undamaged the 2010 Chile earthquake even though they were subjected to demands much larger than the code-specified demand. The approach to model the RC shear walls was validated through comparisons with results experimentally obtained from cyclic static tests conducted on isolated wall specimens. Several pushover analyses were performed to assess the global response of the buildings under seismic actions and to evaluate the influence of several modeling issues. Response history analyses were performed considering a ground motion recorded in Santiago during the 2010 Chile earthquake. In general, results (in terms of both global and local response quantities) are consistent with results given by pushover analysis and with the empirically observed lack of damage, a consistency that was not found in a previous study that considered linearly elastic models. The tangential inter-story drift deformation was found to correlate much better with the lack of observable damage than the total inter-story drift deformation typically considered in practice. The analysis also revealed that foundation uplift is possible but does not seem to significantly influence the response. Other modeling issues that were found to deserve further research are the shear stiffness of the walls and the influence of the slabs.