Transverse Deformation Research Articles

Soil Layer Disturbance Caused by Pipe Jacking: Measurement and Simulation of a Case Study

In this paper, areas of soil disturbed by pipe jack construction are categorized and analyzed in detail. Mechanisms of soil disturbance are discussed and patterns of soil deformation are studied using random medium theory. Lateral deformations in deep soil, pore water pressures, stratified settlement, and earth pressures are investigated using measurements from an electrical transmission pipeline project in China. The measurements show that soil layer movement can be predicted by monitoring changes in pore water pressure, and the amplitude of soil disturbance transverse to the pipeline is larger than that above the pipeline in this project. The distributions of stress components in the direction of, and vertical to, the pipeline axis are studied by numerical simulation. It shows that the closer to the pipeline axis, the greater the additional stress, the faster the attenuation speed, and the smaller the range of influence. Relationships of positive propulsion, friction, and stratum loss with longitudinal and transverse surface deformations are also discussed. The ground displacement is a coupling of the three factors to the action of the soil. The surface transverse subsidence with a main influence range of about ±4 D (D is outer diameter of pipe jacking). The findings from this study can be used as technical foundation and reference for the construction of similar projects.

Modelling hollow pultruded FRP profiles under axial compression: Local buckling and progressive failure

Pultruded Fibre-Reinforced Polymer (PFRP) profiles are widely used as structural elements in many civil infrastructure applications. However, the anisotropic elasticity and the application-driven slenderness make these profiles prone to local buckling failure, well below their ultimate load capacity. In this paper, a numerical study was undertaken to characterise the local buckling and compressive failure of hollow PFRP profiles under axial compression. The Newton method were used along with the adaptive automatic stabilisation scheme and a controlled increment size in Abaqus 2019, to overcome the numerical difficulties in simulating local buckling. The numerical predictions were validated by experiments. The energy parameters and the constituent failure modes of the FEM models were used to explain the effect of dimension, layup, and slenderness ratio on the post-peak behaviour and failure modes of the PFRP profiles. Moreover, the reliance of the strain energy restoration after buckling and the axial and transverse deformations on these parameters was explained.

Analysis on Vibration Characteristics of Flexible Rotating Manipulator

Aiming at the problem that the inertia effect of the tip mass causes the accuracy decrease of the manipulator’s movement, the floating coordinate system was utilized to describe the manipulator’s elastic deformation displacement, and the nonlinear coupling term caused by the transverse deformation was taken into account. According to Lagrange equation of the second type, the system dynamics equation expressed by the modal function was derived. Combined with numerical simulation, the influence of the tip mass on the vibration characteristics of the system was analyzed. Studies have shown that the tip load of the flexible manipulator increases the vibration response amplitude of the system and reduces the response frequency. Reducing the length of the manipulator is beneficial to improve its motion accuracy. Research results have application value for manipulator optimization design and reliability evaluation.

An experimental analysis on the transverse crushing behaviour of Nano-filler reinforced composite cylindrical tubular elements

Thin-walled structures made of nanocomposite materials, could be employed as energy dissipating tubular elements in automobiles owing to its significant characteristics such as lightweight, fracture toughness, enhanced stiffness, and impact energy absorbing ability. The current research work aimed to investigate the transverse deformation behaviour of the hybrid aluminium-nano-filler reinforced glass/basalt fabric polymer composite cylindrical tubes under quasi-static experiments. The progressive crushing behaviour of these tubes were examined from photography. The experimental outcomes revealed that the aluminium-nano-filler reinforced composite tubes buckled displaying an ability of spreading the deformation under transverse compression. The use of multi-walled carbon nano tube fillers reduced the fibre fracturing and ultimately improved the energy absorbing ability of the tubes during crushing process. The nano filler induced tubes with more fabric plies revealed marginally better crashworthiness performance compared to the traditional aluminium-glass/basalt fabric polymer composite tubes.

On size-dependent bending behaviors of shape memory alloy microbeams via nonlocal strain gradient theory

This paper focuses on the size-dependent behaviors of functionally graded shape memory alloy (FG-SMA) microbeams based on the Bernoulli-Euler beam theory. It is taken into consideration that material properties, such as austenitic elastic modulus, martensitic elastic modulus and critical transformation stresses vary continuously along the longitudinal direction. According to the simplified linear shape memory alloy (SMA) constitutive equations and nonlocal strain gradient theory, the mechanical model was established via the principle of virtual work. Employing the Galerkin method, the governing differential equations were numerically solved. The functionally graded effect, nonlocal effect and size effect of the mechanical behaviors of the FG-SMA microbeam were numerically simulated and discussed. Results indicate that the mechanical behaviors of FG-SMA microbeams are distinctly size-dependent only when the ratio of material length scale parameter to the microbeam height is small enough. Both the increments of material nonlocal parameter and ratio of material length-scale parameter to the microbeam height all make the FG-SMA microbeam become softer. However, the stiffness increases with the increment of FG parameter. The FG parameter plays an important role in controlling the transverse deformation of the FG-SMA microbeam. This work can provide a theoretical basis for the design and application of FG-SMA microstructures.

Design-technological optimization of the level of residual deformations during welding of pipe sections from PT-7M alloy

The use of tubular elements in the chemical industry is widely used. The special properties of materials and their reaction to the welding thermal cycle is quite complex. This is especially true of titanium alloys, which when heated are sensitive to environmental influences, require special welding techniques and undergo residual welding deformations. The welded joints of tubular elements made of titanium alloy brand PT-7m, which undergo transverse deformations due to welding, are studied. It is necessary to ensure high-quality sealed welds. Analysis of the literature has shown that to obtain a guaranteed penetration it is necessary to increase the power of the arc discharge or perform multi-pass welding. This will provide larger cross sections of welded parts and should provide the specified strength characteristics. However, this technology, in turn, leads to an increase in residual deformation in the vicinity of the welded joint due to the intensive increase in the coefficient of linear expansion when heating the material. Also, the special thermophysical properties of titanium alloy such as increasing the affinity for gases when heated, increasing the grain size lead to a decrease in strength properties. In the presented work it is proposed to use a mechanical angular deformer with an indicator head and a reference base for the study of transverse residual deformations. Peculiarities of measuring sockets and methods of their preparation are revealed. A calculation scheme for determining the amount of deformation has been developed, which has been tested on flat welded specimens and transferred to tubular elements. The sequence of deformation measurement process is described and the peculiarities of their formation on flat samples and tubular sections are studied. The constructive decision of a welded joint of pipes which provides use of a compensation ring is offered. This approach allows to provide reliable protection of the root of the seam and its optimal formation with minimal residual deformation. At the same time it is possible to reach the reproducible form of a dagger of similar penetration in one pass. The result is a welded joint of the lock type, which is sealed and has a free formation of the seam root with high-quality protection by the gas atmosphere. The use of pulsed arc welding with a non-fusible electrode in an argon environment with filler wire allows to minimize the thermal impact on the base metal. Statistical processing of experimental data on the parameters of the welding mode and their influence on the residual transverse welding deformations is carried out. To obtain an unambiguous statistically reliable answer about the valid law of distribution of experimental data of the results of strain measurement, the balancing procedure and the development of an analytical approximation distribution model are involved. It is shown that the measured values of the residual transverse deformation of the welded assembly are correctly described by the Laplace distribution, which predicts (probability not worse than 90 %) a decrease in the average value of the deformation value by 1.3 times.

Transverse Kähler holonomy in Sasaki Geometry andS-Stability

AbstractWe study the transverse Kähler holonomy groups on Sasaki manifolds (M,S) and their stability properties under transverse holomorphic deformations of the characteristic foliation by the Reeb vector field. In particular, we prove that when the first Betti numberb1(M) and the basic Hodge numberh0,2B(S) vanish, thenSis stable under deformations of the transverse Kähler flow. In addition we show that an irreducible transverse hyperkähler Sasakian structure isS-unstable, whereas, an irreducible transverse Calabi-Yau Sasakian structure isS-stable when dimM≥ 7. Finally, we prove that the standard Sasaki join operation (transverse holonomyU(n1) ×U(n2)) as well as the fiber join operation preserveS-stability.

Buckling and postbuckling behavior of shell type structures under thermo mechanical loads

The thermo mechanical buckling and post-buckling behavior of layered composite shell type structure are considered with the finite element method under the combination of temperature load and applied mechanical loads. To account for through-thickness shear deformation effects, the thermal elastic, and higher-order shear deformation theory is used in this study. The refined higher order theories, that takes into account the effect of transverse normal deformation, is used to develop discrete finite element models for the thermal buckling analysis of composite laminates. Attention in this study is focused on analyzing the temperature effects on buckling and post-buckling behavior of thin shell structural components. Special attention in this paper is focused on studying of values of the hole in curved panel on thermal buckling behavior and consequently to expend and upgrade previously conducted investigation. Using finite element method, a broader observation of the critical temperature of loss of stability depending on the size of the hole was conducted. The presented numerical results based on higher-order shear deformation theory can be used as versatile and accurate method for buckling and post-buckling analyzes of thin-walled laminated plates under thermo mechanical loads.

Study of Transverse Deformation of Porous Alumina during Uniaxial Mechanical Tests

Study of Transverse Deformation of Porous Alumina during Uniaxial Mechanical Tests

Physical and mathematical modelling of rib pillar deformation and failure processes

Underground mining of water-soluble ores is associated with the necessity of mine protection from flooding. Reduction of risks of emergency situations at Perm Krai potash mining enterprises by means of real-time response to underground changes and by organizing appropriate preventive measures contributes to safe subsoil usage and the development of the region.The article presents the main results of research on experimental and theoretical justification for using relative transversal deformation of rib pillars as an informative parameter that allows a rapid assessment of underground mine load-carrying elements for Verkhnekamskoye potash deposit conditions. Experimental studies consisted of physical modelling of pillars deformation and failure processes on the basis of laboratory tests on uniaxial loading of salt rock cubic specimens of large sizes with simultaneous recording of their strain state. Theoretical studies included mathematical description of laboratory tests results and determination of medium model parameters that could reliably describe all stages of salt sample deformation. In order to estimate rib pillars relative transversal deformation values at which yield occurs the adaptation of developed model of medium to stoping room supporting elements taking into account their real size and geometrical form was carried out.

Mechanical properties and bearing capacity of CFRP confined steel reinforced recycled concrete columns under axial compression loading

To study the axial compression behavior of carbon fiber reinforced plastics (CFRP) confined steel reinforced recycled concrete (CSRRC) columns, 11 specimens of CSRRC columns were manufactured and tested under axial compression loading. The design variables in the experiments included the replacement percentage of recycled coarse aggregate (RCA), layers of CFRP, strength of recycled aggregate concrete (RAC), profile steel ratio and slenderness ratio. Subsequently, the failure process and modes, load-displacement curves, stress-strain curves, transverse deformation coefficient and stiffness degradation of the specimens were obtained and analyzed in detail. The experimental results showed that the profile steel yielded before the steel rebars in the columns, then the RAC was crushed, and finally the CFRP broke under axial compression loading. The axial bearing capacity of CSRRC columns decreased with the increase of replacement percentage of RCA and slenderness ratio, respectively. However, the CFRP can give full play to its high-strength confinement performance and effectively improve the axial bearing capacity and deformability of columns. Moreover, the profile steel ratio and strength of RAC have significant effects on the initial stiffness of CSRRC columns, and the stiffness degradation rate of columns decreases with the increase of these parameters. Overall, the CSRRC columns exhibit high axial bearing capacity and good ductility deformation ability. Based on ACI 440.2R-08, the modified formula on the nominal axial bearing capacity of CSRRC columns was proposed in this study. The accuracy on the modified formulae was evaluated by the comparison between the calculated values and test values.

Operational control of rib pillar stability

In room-and-pillar mineral mining, rib pillars should support overlying rock mass for the specified time limit of production. Therefore, one of the mining safety components is monitoring of the behavior of rib pillars in the course of time. For the conditions of the room-andpillar method of mining, the authors propose a monitoring procedure for rib pillar deformation based on operational measurements of horizontal convergence in stopes. The theoretical and experimental research proves that transverse deformation of rib pillars is an informative parameter suitable for generalized assessment of pillar failure. The obtained ranges of critical transverse deformation rates (50–100 mm/m/yr) in rib pillars can tentatively be used as an indicator of the critical stability of load-bearing structures in room-and-pillar mining. In-situ determination of the integral transverse deformation rates in rib pillars is based on the ratio of the measured horizontal convergence in stopes to the width of pillars. Implementation of the proposed approach in the Upper Kama potash salt mines has proved its applicability to identification of rock mass areas where intense deformation is expected. The comparison of the monitoring data of the transverse deformation rates and their critical values determined makes it possible to predict service life of rib pillars, which is very important in terms of safety of mining operations. This study was supported by the Russian Science Foundation, Grant No. 19-77-30008.

The effect of GFRP on reinforcing the buried and internally pressurized steel pipes against terrorist attacks

In recent years, the occurrence of numerous intentional and accidental explosions in buried pipelines, especially in oil and gas pipelines, has been turned to a proper subject of research. The present research, for the first time, studies the utilization of GFRP for reducing the deformation of buried and internally pressurized steel pipes against explosions through the non-linear three-dimensional finite element method. The Combined Eulerian-Lagrangian (CEL) algorithm is used for modeling simulation. It means that the pipe and GFRP are modeled using the Lagrangian algorithm and air, soil and explosives are modeled using the Eulerian algorithm. The studied pipe is API-X65 with an outside diameter of 914.4 mm and the burial depth of 2.5 m. The explosive material is TNT with 10 kg of weight and in the 1 m height below the ground. The results of the model were compared to the results of field tests and the experimental equations presented by previous researchers, and good compatibility was observed. Utilization of GFRP decreases maximum equivalent strain, transverse deformation, longitudinal strain and explosion energy imposed on the pressurized pipeline for about 35.3, 29.6, 13 and 63%; respectively. The internally pressurized pipeline of API-X65 with the wall thickness of 15.88 mm and with the GFRP reinforcement with 7 mm of thickness has acceptable resistance against explosion, in a way that transverse deformation of it is in the acceptable limit and its longitudinal strain is lower than the yield strain. Using the results of this research, we can protect the under-construction or operation buried pipelines against the sub-surface explosions.

Experimental Studies of the Influence of Dynamic Loading on the Elastic Properties of Sandstone

Under dynamic loading, the geomechanical properties of porous clastic rocks differ from those in quasistatic loading. A small experimental rig was built to directly assess the influence of vibrations on the uniaxial compressive strength (UCS), Young modulus, and Poisson’s ratio. A piezoelectric actuator powered by a signal from an oscillator was used in the rig as a generator of vibrations. A laser sensor and eddy current probe measured the longitudinal and transverse deformation. Tinius Hounsfield and Instron Series 4483 installations were used to determine the geomechanical properties of new red sandstone in a quasistatic regime. The boundaries of elastic deformations determined in the quasistatic loading were implemented in the dynamic loading. To perform the experiments in the elastic zone (on the graph of stress (σ)–strain (ε)), small samples with diameters ranging between 7.5 and 24.7 mm were manufactured. The investigation demonstrated that the Young’s modulus of the sandstone increased with increasing values of the dynamic load and frequency.

A low order, torsion deformable spatial beam element based on the absolute nodal coordinate formulation and Bishop frame

Heretofore, the Serret–Frenet frame has been the ubiquitous choice for analyzing the elastic deformations of beam elements. It is well-known that this frame is undefined at the inflection points and straight segments of the beam where its curvature is zero, leading to singularities and errors in their numerical analysis. On the other hand, there exists a lesser-known frame called Bishop which does not have the caveats of the Serret–Frenet frame and is well-defined everywhere along the beam center-line. Leveraging the Bishop frame, in this paper, we propose a new spatial, singularity-free low order beam element based on the absolute nodal coordinate formulation for both small and large deformation applications. This element, named ANCF14, has a constant mass matrix and can capture longitudinal, transverse (bending) and torsional deformations. It is a two-noded element with 7 degrees of freedom per node, which are global nodal coordinates, nodal slopes and their cross-sectional rotation about the center-line. The newly developed element is tested through four complex benchmarks. Comparing the ANCF14 results with theoretical and numerical results provided in other studies confirms the efficiency and accuracy of the proposed element.

Construction of peridynamic beam and shell models on the basis of the micro-beam bond obtained via interpolation method

Peridynamic (PD) theory is suitable for predicting structural damages, such as crack propagation and multiple crack growths. However, it is computationally more expensive than finite element method (FEM). Structural idealization is an useful method to improve computational efficiency, especially for complex structures. This study presents a new strategy for general PD beam and shell models on the basis of the micro-beam bond; in this strategy, the bond deformation is obtained directly through the interpolation method, the micro potential energy of the bond can be built, and the micro moduli of the beam and shell models can be solved spontaneously. The Euler beam and Kirchhoff plate theory are used for bending deformation in this study. Each endpoint of the micro-beam bond has three translational degrees of freedom (DOFs) and three rotational DOFs simultaneously. The force and displacement formulations of the micro-beam bond are completely similar to the FEM beam element, which is naturally suitable for the coupling of PD and FEM. Transversal deformation is captured accurately due to the high-order relationship with the transversal forces/moments and transversal displacements of the micro-beam bond. Moreover, no material parameters are limited in the model. Simulation results show the precision of the presented PD beam and shell models on the basis of the micro-beam bond.

An Improved Approach to Direct Simulation of an Actual Almen Shot Peening Intensity Test with a Large Number of Shots.

In existing simulations of the Almen intensity test, arc height is indirectly obtained by an equivalent method including a representative cell, a few shots and equivalent loading. Most of these equivalent methods cannot consider the transverse deformation of the strip, the complex stress state of the plastic hardening layer and process parameters, resulting in deviation from the actual test. This paper introduces an improved and experimentally validated discrete element model (DEM)-finite element model (FEM) to predict the actual Almen intensity. The improvement of this model is mainly reflected in the large and real number of shots involved in the actual Almen intensity test, shot–shot interactions, and real-size solid finite element model of the Almen strip. A new method for calculating the shot stream is proposed based on the test and considering test process parameters such as the mass flowrate, nozzle movement speed and nozzle–workpiece distance. The shot stream impacting the strip with a fully restrained underside was first simulated in improved DEM-FEM to bring the forming energy. As a second step, an implicit solver of the Almen strip FEM calculates the spring-back to simulate strip removal from the holder. The results achieved by the present approach are compared with the results obtained by the experimental results and those in the literature. The results show that the arc height and Almen intensity obtained by the present approach match much better with the literature than the traditional method. Some new results obtained by the improved coupling DEM-FEM method are presented. The influences of the transverse deformation and surface plastic layer on the deformation of the Almen strip are discussed. This improved method provides an alternative characterization method for precision peen forming simulation.

Investigation of the Effect of Inhomogeneous Material on the Fracture Mechanisms of Bamboo by Finite Element Method.

Bamboo is a remarkably strong and sustainable material available for construction. It exhibits optimized mechanical characteristics based on a hollow-inhomogeneous structure which also affects its fracture behavior. In this study, the aim is to investigate the effect of material composition and geometrical attributes on the fracture mechanisms of bamboo in various modes of loading by the finite element method. In the first part of the investigation, the optimized transverse isotropy of bamboo to resist transverse deformation was numerically determined to represent its noticeable orthotropic characteristics which prevail in the axial direction. In the second part of this study, a numerical investigation of fracture mechanisms in four fundamental modes of loading, namely bending, compression, torsion, and shear, were conducted by considering the failure criterion of maximum principal strain. A crack initiation stage was simulated and compared by implementing an element erosion technique. Results showed that the characteristics of bamboo’s crack initiation differed greatly from solid geometry and homogeneous material-type models. Splitting patterns, which were discerned in bending and shear modes, differed in terms of location and occurred in the outside-center position and inside-lowermost position of the culm, respectively. The results of this study can be useful in order to achieve optimized strength in bamboo-inspired bionic designs.

Vibrations and stability analysis of double current-carrying strips interacting with magnetic field

Interactive vibrations and buckling of double current-carrying strips (DCCS) are investigated in this study. Considering the rotational and transverse deformation of the strip, four coupled equations of motion are obtained using Hamilton’s principle. Using the Galerkin method, mass and stiffness matrices are extracted and the stability of the system is determined by solving the eigenvalue problem. Effects of pretension and elevated temperature on the stability of DCCS are studied for three types of materials and various arrangements. Finally, the effect of horizontal or vertical distance between strips on the critical current value is investigated. According to the results, the effects of temperature rise, pretension, and the relative distance of the strips on the instability of DCCS are found to be significant.

Research on influence of Web spacing of bogie side member on welding deformation

In the production process of bogie, welding is one of the important production technologies. To study and control the welding deformation of bogie frame side beam to make the deformation value within a reasonable range has very important practical significance for the production of bogie side beam. The research content of this paper will take high-speed EMU bogie frame side beam as the research object. Set different web spacing, compare the welding deformation value, explore the influence of structural stiffness on the welding deformation of side beam, and use MATLAB software to curve fitting the welding deformation value, the research shows the distribution law of transverse, longitudinal, vertical and comprehensive welding deformation, and fits the mathematical equation between the web spacing L and longitudinal deformation SX, vertical deformation SY, transverse deformation SZ In this paper.