Influence Of Axial Force Research Articles

Process parameter assessment on the dissimilar deposition of AA2024-T351 on AA7475-T761 by friction surfacing

Friction surfacing as a solid-state deposition process allows the joining of materials with different chemical and physical properties at temperatures below their respective melting points. This experimental work focuses on generating sound, defect-free metallurgical joints between single friction surfacing deposits and substrate surfaces from dissimilar Al alloys of the 2xxx and 7xxx series. In this context, the influence of axial force and deposition speed on surface morphology and deposit geometry of the two heat-treatable Al alloys AA7475 as substrate and AA2024 as deposit are investigated. Process parameter variation shows that an increase in axial force from 8 to 12 kN, in conjunction with a deposition speed of 8 mm/s, leads to smooth surface morphology and consistent deposit width along its length. The AA2024 deposits consist of fine-grained microstructure with higher hardness at the top and lower hardness at the deposit-substrate interface. The joining mechanism is by interdiffusion, with a 7.5 μm thick diffusion zone across the dissimilar interface. Three-point bending tests reveal excellent bonding in the lateral surface of the advancing side due to the absence of delamination for all conditions tested. Minor delamination appears predominantly on the retreating side region for process parameter sets with low axial force. Tensile test results reveal that the AA2024 deposit on the AA7475 substrate presents an ultimate tensile strength equivalent to the AA7475-T651 base material and an increase of 37 % in ductility.

Analysis of the seismic performance of a large underground station structure in complex stratum considering the influence of axial force

The large underground structure in saturated stratum is vulnerable to float during an earthquake. This results in a plethora of problems, such as uneven settlement, large internal force and structure damage. In this study, the seismic behavior of a three-story, two-span subway station in complex saturated stratum was investigated through water-soil fully coupled 3D finite element method. In the analysis, the nonlinear soil behavior was described by a cyclic mobility model and the structure was calculated using a nonlinear constitutive model which can consider the influence of axial force on its bending moment. Joints elements were used to model the contact surface between soil and structure. The development of the soil displacement and internal force of the station structure at different times during a huge earthquake was examined. The bearing capacity of the station structure members was analyzed. The results indicated that the vertical displacement was spatially distributed. The larger additional seismic stresses appeared in the bottom slab and side wall. Failed elements were observed in both the walls and slabs, and the walls were more easily damaged than the slab. The results provide useful reference for the large underground structure seismic design in the construction of urban underground space.

Thermal buckling and postbuckling of functionally graded multilayer GPL-reinforced composite beams on nonlinear elastic foundations

Under the influence of axial forces and uniform temperature variations, the thermal buckling and postbuckling of composite beams reinforced of functionally graded multilayer graphene platelets (GPLs) resting on nonlinear elastic foundations are examined. The Halpin-Tsai model is used to calculate the elastic modulus of each layer of GPL-reinforced composite (GPLRC). According to the virtual work principle, the nonlinear governing equations for the beam are obtained from the first-order shear deformation beam theory. The impact of axial force and nonlinear elastic foundation on thermal buckling and postbuckling is discussed using the differential quadrature method (DQM), and the analytical expression is given by the two-step perturbation method (TSPM). The effects of axial force, boundary conditions, slenderness ratio, GPL geometry, GPL weight fraction, GPL distribution pattern, and elastic foundation coefficient on thermal buckling and postbuckling are examined through parameter analysis.

Modeling and Investigation of the Velocity-Dependent Cutting Process with PDC Cutters Using the Discrete Element Method

Polycrystalline diamond compact (PDC) bits with multiple fixed cutters drill through deep formations and are used in oil and gas, geothermal, and mining industry. The bit-rock interaction excites drill string vibrations, which need to be mitigated to improve drilling performance. A velocity-weakening characteristic of the bit torque can cause severe self-excited high-frequency torsional oscillations (HFTO) of the bottom hole assembly (BHA). The dependency on velocity can be attributed to rate-sensitive rock cutting forces at each cutter. The purpose of this paper is to model the rate effect of cutting forces and determine influencing factors in the single-PDC cutting process. In this paper, a modified bonded-particle model (discrete element method, DEM) for rock in deep drilling environments is applied to the pressurized cutting process. Potential modification strategies considering rate indicators at different scales are compared and discussed to reproduce rate dependency in the particle contact model. Two specific models, incorporating cutting-speed-dependent bond strength or grain elastoplasticity, are implemented and verified. The relationship between rate-sensitive cutting forces and the causal rock failure mechanisms is then clarified by interpreting the results from a continuum perspective. Moreover, the influences of axial force and cutter wear state on the rate dependency are investigated. In cutting simulations at a constant depth of cut and various cutting speeds, both models result in rate-dependent cutting forces in good qualitative agreement with rock experiments: Significant hardening is reflected in the axial force component. The modification of contact models combined with a macroscopic rate indicator (i.e. cutting speed) has proven to be a feasible and effective way to reproduce the rate effects in the cutting simulations. In subsequent simulations with constant axial force, the steady-state tangential force decreases as the cutting speed increases, matching the reduction of torque on the bit with increasing RPM. Rate dependency intensifies at higher axial forces or with dull cutters, which agrees with laboratory full-scale bit tests in the literature. This study proposes a practical approach to integrating observed rate effects of downhole rock cutting processes into numerical rock models. The results enhance our understanding of the rock cutting process and have positive implications for the improvement of the cutter design against undesirable rate effects.

Dynamic analysis on monopile supported offshore wind turbine under wave and wind load

Monopile offshore wind turbine (OWT) accounts for more than 65% of all OWT types. Monopile OWT is a soil-pile-tower system and can be divided into three stages: the stage embedded in the soil, the stage submerged in the seawater and the stage exposed to the air. Based on the improved Tajimi formulation and dynamic principle, this paper establishes a three-stage monopile OWT model to predict the dynamic response of the structure. The displacement of the tower under different wind velocities is obtained. The solution is compared with the Finite Element Method (FEM) result to verify its correctness. The influences of different parameters on the structure are discussed. The results indicate that the structure natural frequency is sensitive to the tower length and nacelle-rotor mass. The increasing seawater depth due to scour effect can significantly decrease the foundation stiffness. The influence of axial force and wave load on the foundation stiffness is also investigated. The tower diameter and tower wall thickness are found of vital importance to the tower displacement.

Finite Element Analysis of the Limit Load of Straight Pipes with Local Wall-Thinning Defects under Complex Loads

Local wall thinning is a common defect on the surface of pipelines, which can cause damage to the pipeline under complex pipeline loads. Based on the study on the limit load of straight pipes with defects, the nonlinear finite element method was used to analyze the limit load of straight pipes with local wall-thinning defects under internal pressure, bending moment, torque, axial force, and their combinations, and the empirical limit-load equations of straight pipes with local wall-thinning defects under single and complex loads were fitted. Based on the allowable load on the equipment nozzles, the influences of torque and axial force on the load-bearing capacity of straight pipes with local wall-thinning defects were quantitatively analyzed. For medium and low-pressure equipment, the load-bearing capacity was reduced by 0.59~1.44% under the influence of torque, and by 0.83~1.80% under the influence of axial force. For high-pressure equipment, the load-bearing capacity was reduced by 10.07~20.90% under the influence of torque, and by 2.01~12.40% under the influence of axial force.

Numerical Simulation of the Effect of Freeze–Thaw Cycles on the Durability of Concrete in a Salt Frost Environment

In order to improve the accuracy of the analysis of the impact of freeze–thaw cycle on concrete durability in a salt freezing environment, the numerical simulation of the impact of the freeze–thaw cycle on concrete durability in a salt freezing erosion environment is studied in this paper. Firstly, considering the influence of axial force and bending moment on the relationship between bending moment and curvature, a concrete fiber beam column model is established. Then, according to the joint influence of temperature field, stress field and seepage field on concrete in the process of freezing and thawing, the control differential equation of the freezing and thawing cycle is established. The freeze–thaw damage section is divided, the non-uniform distribution of freeze–thaw damage is determined, and the division of the freeze–thaw damage section is completed. According to the linear relationship between freeze–thaw damage degree, relative dynamic elastic modulus, freeze–thaw cycle times and position variables, the durability of concrete is numerically simulated, and the attenuation law of bond strength at different section depths after freeze–thaw is determined. The results show that the temperature curve simulated by the design method is consistent with the actually measured temperature curve, which can better reduce the temperature change of the inner core of the test block during freezing and thawing, and the relative dynamic elastic modulus is in good agreement with the actual value, which can prove that the method in this paper has certain practical application value. It is expected to provide some reference for solving the durability problem of concrete in a salt frost erosion environment and the optimal design of concrete structures.

Influence of axial force and corrosion on failure of prestressed concrete structures considering M-V interaction

Existing prestressed concrete structures suffer from degradation of prestressing for two main reasons: a defect of the sheath infills (cement grout) of bonded tendons, and corrosion of steel strands. These two causes, often concomitant, lead to a reduction over time of the effectiveness of initial prestressing, in addition to the ordinary tension losses due to concrete shrinkage and creep, and to steel relaxation. In many cases a consequence of bad grouting in bonded tendons is that the structure shows an intermediate behavior between that of external prestressing and that of internal bonded prestressing. This, added to damage to wires due to corrosion, makes it essential for the designer to be able to check sections of existing structures considering the interaction between the characteristics of the stress together with the changing state of tendons.In this paper a methodology for performing safety checks through M-V interaction domains with axial force N due to prestressing and external loads in the structural scheme is presented. The modification of the behavior between the intact and the degraded section due to corrosion and the consequences of bond loss are shown and discussed together with the influence of compressive axial force due to the structural scheme. Finally, an application is proposed on an emblematic case study: the deck sections of the Polcevera viaduct in Genoa.

Influence of axial force and characteristics of axial force affecting on total knee replacement constraint test

The result of testing for determination of Total Knee Replacement (TKR) Constraint (ASTM F1223) is necessary for surgeons for matching the knee prosthesis with the different degrees of severities of knee osteoarthritis patients. In the knee replacement constraint test, the axial compressive load and translation displacement are the control and the adjusting variables. The magnitude of axial compressive load during testing is affected by the slope of knee bearing surface. According to ASTM 1223 standard, the axial compressive load is not clarifyingly mentioned. Namely, it should be equal 710 N during testing or only in state of initiation. It may lead to testers to perform the test into different two modes which consequently in possibly different constraint result. Therefore, the objective of this research is to clarify the differences in test results when applying two axial compressive load characteristics during testing. The six-axis testing machine (Prosim Universal Joint Simulator) was used to determine the anterior posterior constraint (AP) of fix bearing posterior sacrifice (FB PS) system. Bovine serum was directly applied to the bearing surfaces as a lubricant. An initial axial compressive load 710 N was used. Two axial compressive load characteristics during testing, 1) keeping the axial force at given value as mentioned during testing (load-controlled testing) and 2) with allowing the change in axial compressive load during testing (displacement-controlled test), were used. From the results, the AP load resistance hysteresis loop patterns obtained by both testing modes were similar. The magnitude in forward direction load resistance is higher, while the backward AP load resistance showed the lower, in case of displacement control mode. It resulted in span between AP load resistance was larger. Moreover, the higher constraint in case of displacement control was indicated. Thus, if the test modes are not mentioned in test result, the surgeons will be possibly choosing the wrong TKR for their patient.

Influence of Axial Force on the Microstructure and Mechanical Properties of 2A70 Aluminum Alloy Friction Pull Plug Welding

Influence of Axial Force on the Microstructure and Mechanical Properties of 2A70 Aluminum Alloy Friction Pull Plug Welding

On the bifurcation buckling and vibration of porous nanobeams

In the present paper, effects of porous material on bifurcation buckling and natural vibrations of nanobeams are investigated based on the higher-order nonlocal strain gradient theory. The displacement field of the nanobeam satisfies assumptions of Reddy higher-order shear deformation beam theory. The displacements gradients are assumed to be small so that the components of the Green-Lagrange strain tensor are linear and infinitesimal. The constitutive relations for functionally graded porous material are expressed by nonlocal and length scale parameters and power-law variation of material parameters in conjunction with cosine functions to create a possibility to investigate the effect of diverse distributions of porosity on mechanics of nanostructures. Effect of Winkler-Pasternak foundation on mechanics of nanobeam is also considered. The Hamilton’s variational principle is utilized to derive governing equations of motion of the composite nanobeam. For the first time, the critical porosity is defined and examined for bifurcation buckling analysis of elastically supported nanobeams with symmetric distribution of porosity. Influence of axial forces and types of porosity distributions on eigenfrequencies of functionally graded nanobeams is studied. Classical theory without nonlocal effects is obtained as a special case and valid for all considered distributions of functionally graded material and volume fractions of voids.

Geometric nonlinear dynamic analysis of tapered steel members

In this study, a theoretical analysis is presented for estimating the in-plane geometric nonlinear elastic stability behavior of steel members with tapered elements under dynamic loads. Beam-column approach is adopted for modeling the structural members as beam-column elements. The formulation is based on the Eulerian description taking into consideration the influence of axial force on bending stiffness. The changes in member chord length due to axial deformation and flexural bowing are also considered. In the dynamic analysis, the system mass properties have been represented using both lumped and consistent mass matrices. The consistent mass matrix is derived in three components: translational, rotational, and axial inertia. The formulation of the mass matrices in local and global coordinate systems of tapered members, which incorporates geometric nonlinearity, has been presented. A parametric study is conducted to examine the effects of number of tapered elements, tapering the prismatic members, time step size, and tapering ratio. The dynamic responses of tapered members have been shown to be significantly affected by these parameters.

Theoretical research into cyclic web buckling and plastic overstrength of shear links

In this paper, a numerical model for shear links was firstly established and carefully validated, and the cyclic web buckling behavior were also discussed with comparison to experimental results. On this basis, firstly, the influence of boundary conditions was explored. The influence of axial displacement constraint on cyclic buckling and plastic overstrength was discussed, and a theoretical plastic overstrength factor considering axial displacement constraint was proposed. In addition, the influence of axial forces on cyclic buckling and plastic overstrength was discussed, and the limited range of axial forces on shear links was recommended. Afterwards, the influence of various parameters on cyclic web buckling was analyzed and discussed, and a theoretical prediction approach for cyclic buckling angle was proposed, which was applicable to shear links with or without stiffeners. Also, the influence of parameters on plastic overstrength was analyzed and discussed, and the theoretical model of the relationship between plastic overstrength and displacement angle was proposed for shear links with or without stiffeners. Finally, based on the works above, a simplified theoretical model to predict the relationship between shear force and displacement angle was proposed, with consideration of cyclic buckling. The experimental validations confirmed it had good accuracy. • The influence of axial boundary conditions on cyclic web buckling and plastic overstrength of shear links was discussed. • The cyclic web buckling was parametrically studied, and a theoretical approach predicting buckling angle was given. • The plastic overstrength was parametrically studied, and a theoretical prediction approach was given. • The theoretical prediction model for skeleton curve of shear links was proposed, which gave good prediction results.

The Influence of Tian Gan Deflection on the Flatness of Hanging Scrolls in Chinese Painting and Calligraphy

ABSTRACT The forms of traditional Chinese painting and calligraphy are varied, including hanging scrolls, horizontal scrolls, screens, hand scrolls, and albums. Hanging scrolls are hung on the wall for display, but curling edges often appear on both sides of the hanging scroll. Various factors influence the deformation of paintings and calligraphy, such as temperature and relative humidity and the susceptibility of materials in scrolls as well as mounting techniques. The influences of structural components, such as tian gan (hanging rod), hanging rope, and di gan (lower rod) have received little attention. This paper focuses on the influences of tian gan deflection on the deformation of hanging scrolls, with the help of DIC (digital image correlation) visualization. Deflections of tian gan in two types of hanging methods were compared with a theoretical study. It was suggested that the influence of axial force was of great importance on the increase in deflection and bending moment. To reduce the bending of tian gan as much as possible, the vertical hanging method with appropriate position for the hanging rope should be chosen for mounting hanging scrolls.

Lateral impact behavior of double-skin steel tubular (DST) members with ultra-high performance fiber-reinforced concrete (UHPFRC)

This study investigates the lateral impact behavior of double-skin steel tubular (DST) members with ultra-high performance fiber-reinforced concrete (UHPFRC). A total of six specimens were prepared and tested under lateral impact loading. In addition to UHPFRC filled DST members, normal strength concrete (NSC) filled DST member was also tested for comparison. Other investigated parameters in this study include the impact energy, the outer steel tube thickness, the inner steel tube thickness, and the presence of axial force. The test results demonstrate that the UHPFRC filled DST members exhibit significantly higher lateral impact resistance capacity than the NSC filled DST member. The impact energy and the outer steel tube thickness significantly affect the lateral impact behavior of UHPFRC filled DST members, while the influence of inner steel tube thickness is insignificant. With the applied axial force in this study, the influence of axial force is also insignificant. Afterwards, numerical model was developed and validated by the present test results. Based on the validated numerical model, the mid-span bending moment distributions and the stress wave propagations were investigated. Finally, parametric analyses were carried out to investigate the influences of different parameters on the lateral impact behavior of UHPFRC filled DST members.

Coupled axial tension-flexure behavior of slender reinforced concrete walls

Reinforced concrete (RC) walls in high-rise buildings, in particular wall piers that form part of a coupled or core wall system, may experience coupled axial tension-flexure loading when subjected to lateral demands. The seismic behavior of RC walls with various axial tensile forces was investigated by quasi-static tests on four RC slender walls subjected to the combined tension and flexure loading. The failure modes, strength and deformation capacity, effective flexural stiffness, and design equations are presented. The failure modes included flexural-sliding failure and flexural failure. The effective flexural stiffness and lateral strength of the walls significantly decreased as the axial tensile forces were increased. The ACI 318-14 and ASCE/SEI 41-13 code provisions overestimated the effective flexural stiffness of RC walls subjected to axial tension. Although equations proposed by Paulay & Priestley and Adebar et al. consider the influence of axial forces, they were not able to accurately predict the effective flexural stiffness of the RC wall specimens subjected to tensile forces. Both sectional analysis using XTRACT and JGJ 3-2010 (China) code equations provided accurate estimation of the flexural yield strength of walls. Finally, both a refined model and simplified equation were proposed to estimate the axial elongation for RC slender walls subjected to axial tensile force and cyclic lateral loading.

Influence of Axial Force on Tensile Strength and Microstructural Characteristics of Friction Stir Buttwelded Aluminum Alloy/Steel Joints

In this work, the effect of axial force on the tensile strength, microhardness, joint interface microstructure and fracture surface morphology of friction stir welded (FSW) dissimilar butt joints of 3 mm thick aluminum (Al) alloy AA5052-H32 and HSLA steel IRS-M42-97 were investigated. The FSW trials were carried out by varying the axial force from 5–9 kN while keeping the other parameters constant. The highest joint strength of about 90% of the ultimate tensile strength (UTS) of the base Al alloy is obtained at 7 kN axial force. It is found that axial force in the range, 6–8 kN could produce joints with joint strength above 75% of the UTS of the base Al alloy. EDS and XRD analysis suggests that the intermetallic compound (IMC) layer formed at the joint interface is consistent with FeAl3 and FeAl at lower and higher axial forces, respectively. Joint interface analysis shows that the thickness of IMC layer formed at the interface is critical in the performance of the joint and the joint with an average IMC layer thickness of about 1 μm at the joint interface has exhibited the highest joint strength.

A practical analytical model for special concentrically braced frames

Special concentrically braced frames (SCBFs) are extensively used in high seismicity regions because of structural efficiency and high ductility for energy dissipation. SCBFs exhibit large inelastic deformation through tensile yielding, buckling and post-buckling behaviors of braces. A simple and accurate model for brace with low computational cost is vital to capture the complex structural behavior of SCBFs. The previous researches generally recommended ten elements per brace, which significantly increases both modeling and computer time. In this paper, a new hybrid flexibility-based beam-column element, considering initial geometrical imperfection and residual stress explicitly, distributed plasticity along member length, and semi-rigid behavior of gusset plate connections is proposed for modeling of SCBFs. It is worth to point out that the zero-length springs attached to element ends for simulation of gusset plate connections can consider the influence of axial force, which has not been reported in literature. Furthermore, the influences of initial geometrical imperfection and residual stresses on the performance of SCBFs are firstly evaluated on the basis of direct analysis method (DAM) specified in AISC360 (2016) and Eurocode-3 (2005). As all dominant factors affecting structural behaviors have been considered, the proposed method using one-element-per-member model provides sufficiently accurate results for practical design with enhancement of computational efficiency. Several examples illustrate the accuracy and efficiency of the proposed model for performance-based seismic design of SCBFs.

Modelling of Bolted Endplate Connections Subjected to Bending Moment and Axial Force in Fire

This article presents an extensive application of component based method both at ambient and elevated temperatures. The analytical model is used to predict the connection behavior, with axial force in the connected beam being superposed. The formulas for the calculation of bending moment resistance and rotation stiffness are derived in the article. At the same time, two kinds of loading paths, proportional loading and non-proportional loading, are also thoroughly investigated. A total of 12 tests, in which the connection is subjected to proportional loading path, are utilized to validate the analytical model. At the same time, a 3D Finite Element Model using the ABAQUS is also presented to verify the analytical model. As to the connection under non-proportional loading path, 6 transient fire tests are chosen to verify the proposed model. Compared to the experimental results, the accuracy of the moment-rotation curves obtained from the analytical model are acceptable. Hence, the presented analytical model can be used to predict connection behavior under fire conditions, taking the influence of axial force into account.

Introduction of a hybrid sensor to measure the torque and axial force using a magnetostrictive hollow rod

In this paper, a hybrid sensor to measure the torque and axial force using a magnetostrictive hollow rod is presented. The magnetostrictive material is made up of vanadium permendur alloy. Axial and circular magnetic fields are used in order to excite the sensor. An axial coil and a single wire passing through the material are used in order to generate axial and circular magnetic field, respectively. In order to detect axial and circular flux changes, two orthogonal pickup coils are used. Theoretical modeling of the sensor has been done using piezomagnetic equations of magnetostrictive materials. In order to achieve an estimation of applied magnetic fields to the material, the sensor has been simulated numerically. Then, the sensor has been fabricated and tested under influence of axial forces and torques. Tests show that the sensor can detect and measure the axial force and torque simultaneously. Applying torque causes changes in circular magnetic flux density and applying axial force causes changes in both circular and axial fluxes. That is an indicator for load type detection of the sensor. The ranges of the axial force and torque measurement are 10 kN and 20 N m, respectively. The torque measurement accuracy of the sensor is ±14.81% FS, measurement sensitivity of the axial pressure load is 0.012 mVN and measurement sensitivity of the torque is 1.18 mVN∙m.