Effect Of Eccentric Loading Research Articles

Three-dimensional turning force sensor based on a decagonal ring structure: crosstalk mitigation design and performance optimization

Abstract Real-time data acquisition using high-precision three-dimensional turning force sensors is crucial for intelligent manufacturing. However, existing sensors face challenges such as low integration levels and poor crosstalk resistance, rendering them inadequate for high-precision measurements. Theoretical analysis has demonstrated that a fully centered decagonal ring structure can effectively mitigate the effects of eccentric loading. This study focuses on designing a fully centered turning force sensor with minimal crosstalk. To achieve a balance between sensitivity and stiffness, multi-objective optimization was conducted using GWO-BP and TOP algorithms, resulting in a twofold increase in the sensitivity of the decagonal ring. The sensor design incorporates metallic strain gauges, instrumentation amplifiers, and peripheral circuits into the ring arms of the decagonal structure. Experimental results show that the sensor’s amplified sensitivities in the Fc, Ff, and Fp directions are 11.78 mV N−1, 10.31 mV N−1, and 1.78 mV N−1, respectively. The first three natural frequencies in an unconstrained state are 2518.5 Hz, 2537.5 Hz, and 4256.4 Hz. The sensor’s Fc-Fy crosstalk ranges from 0.18% to 0.88%, with noise limits for the Fc, Ff, and Fp directions of 0.035 N, 0.03 N, and 0.23 N, respectively. Cutting experiments have demonstrated that under varying spindle speeds and cutting depths, the sensor effectively detects surges in cutting force caused by rapid tool retraction, as well as other common faults.

The Influence of Eccentric Muscle Actions on Concentric Muscle Strength: An Exception to the Principle of Specificity?

The principle of specificity suggests that the largest changes in strength occur when training resembles the specific strength test. A one-repetition maximum (1RM) test, which tests the maximal concentric strength, is commonly used as a surrogate for strength adaptation. When separating muscle actions into concentric or eccentric phases, multiple lines of evidence suggest that eccentric muscle actions possess several distinct physiological properties compared with concentric actions. In accordance, there are instances where the increases in 1RM strength test were similar between eccentric-only and concentric-only resistance training. This is at odds with the principle of specificity which suggests that individuals who trained with concentric actions would be expected to have an advantage in that specific task. Although the mechanistic reasons why eccentric-biased training carries over to maximal concentric strength remains to be elucidated, the lack of discernible differences in strength gains with eccentrically-biased training (e.g., eccentric-only and accentuated eccentric training) may imply that the effects of eccentric loading in training are transferable to concentric strength. Our review revisits the role of eccentric loading in enhancing concentric maximal muscle strength. We also speculate on potential physiological factors (i.e., molecular and neural factors) that may differentiate the effects of eccentric and concentric resistance training on the changes in muscle strength. Currently, the majority of the studies investigating the changes in strength have been conducted using isokinetic eccentric training. This is important as there is a viewpoint that the magnitude of chronic adaptations with different modalities of eccentric exercises (i.e., isotonic, isokinetic, and isoinertial training) may also differ from each other. While it has been suggested that eccentric action has a greater transferable capacity for strength adaptations compared to concentric actions, future investigations are warranted to investigate with different modalities of eccentric exercises. There also remains a host of unanswered questions related to the role of eccentric action for maximal concentric strength. For example, future studies may examine whether the eccentric action would be additive when the training is already maximally loaded during the concentric action for increasing concentric maximal strength. We suggested a few different designs that could be used to answer some of these questions in future studies.

Criticality safety analysis for eccentric loading of fuel assemblies in spent nuclear fuel cask

Eccentric fuel loading is one of the studies performed in a spent nuclear fuel criticality safety analysis. Several studies have been performed to investigate the effect of increasing reactivity on eccentric loading and random displacement in spent nuclear fuel pools; However, studies within spent nuclear fuel casks have not been performed. Therefore, this study investigates the effects of eccentric loading and random displacement of fuel assemblies on the reactivity in the spent nuclear fuel cask. The spent nuclear fuel cask and PLUS7 fuel are modeled using the MCNP code to investigate these effects. The result indicates that in eccentric cases, the k-effective values exceed those observed in the normal case. Also, several random displacement cases show k-effective values that exceed the normal case. These results differ from previous studies on eccentric loading in the spent fuel pool. It supports the necessity of considering both eccentric loading and random displacement in the criticality safety analysis in spent nuclear fuel cask. The increase in reactivity due to eccentric loading and random displacement of fuel assemblies within casks might be considered in criticality safety analysis and regarded as an uncertainty.

A Coupled Effect of Eccentric Loading and Upward Seepage on Collapse Settlement of Strip Footings on Reinforced Sand

A Coupled Effect of Eccentric Loading and Upward Seepage on Collapse Settlement of Strip Footings on Reinforced Sand

Effects of eccentric loading on performance of concrete columns reinforced with glass fiber-reinforced polymer bars.

Glass fiber-reinforced polymer (GFRP) reinforcements are superior to traditional steel bars in concrete structures, particularly in vertical elements like columns, and offer significant advantages over conventional steel bars when subjected to axial and eccentric loadings. However, there is limited experimental and numerical research on the behavior of GFRP-reinforced concrete (RC) columns under eccentric loading having different spacing of stirrups. In this study, six specimens were cast under three different values of eccentricities (25mm, 50mm, and 75mm) with two groups of stirrups spacing (50mm and 100mm). The experimental results showed that by increasing the eccentricity value, there was a reduction in the load-carrying capacityof the specimens. The finite element ABAQUS software was used forthe numerical investigation of this study.The results from the finite element analysis (FEA) were close to the experimental results and within the acceptable range. The maximum difference between theexperimental and FEA resultswas 3.61% for the axial load and 12.06% for the deformation.

Effect of eccentric loads on the behavior of circular footing with/without skirts resting on sand soil

The stability of circular footings under eccentric vertical loads is a significant problem in geotechnical engineering. Therefore, this paper shows the results of experimental tests carried out on an eccentrically loaded circular foundation on sand soil. The focus of this research is on examining how eccentric loads affect the behavior of circular footings on sand soil, both with and without skirts. Various load eccentricities (e) equals zero, 2.50, 5.00, 7.50, 10.00, 12.50, 15.00, 17.50 and 20.00 mm are used. In addition to, a 60 mm-diameter circular foundation and sand with an 85% relative density (Dr) are used in this experimental study. To study the effect of changing the skirts depth on the load-settlement response skirts with different depths (h) = 60 mm, 150 mm, 240 mm are used for vertical reinforcement. In comparison to the unreinforced condition, test findings show an improvement in ultimate bearing capacity. When the skirts are positioned at the ideal embedment depth L/D = 4, it is found that the circular footing's load-settlement behavior is enhanced by 92% and 93% in case of using (e/D) ratio = 0.125 and 0.25 compared to the unreinforced case.

Effect of eccentric loading on fatigue cracking mode and characteristics of diaphragm-to-rib welded joints in steel bridge deck

The non-uniformly distributed wheel loads in orthotropic bridge decks will cause its lower components to be eccentrically loaded. By conducting numerical simulation, field measurement and fatigue tests of diaphragm-to-rib welded joints (DU), the crack-growth characteristics under eccentric loading were analyzed and compared with that under symmetric loading, through which the warning crack length for maintenance and an evaluating method for crack-growth rates were proposed. The result demonstrates that the eccentrically loaded side (ES) of DU will crack ahead of non-eccentric side (NES) with a larger growth angle. The crack performs the same three-stage features of fast-slow-rapid growth under eccentric loading with demarcations of 27 mm and 70 mm, which are obviously larger than that under symmetric loading. The weld toe on NES will be particularly prone to fatigue cracking once the crack on ES enters the third rapid-growth stage. The new initiated crack on NES will own the same growth rate as ES. The demarcation 70 mm shall be taken as the warning length for crack maintenance to avoid cracking on the other side. It is appliable to evaluate the crack-growth rate of DU by Paris formula and the maximum stress intensity factor obtained by K I and K II of mixed mode cracks.

Fatigue cracking characteristics of components stiffened with vertical ribs under eccentric loading in steel bridge deck

The components in orthotropic steel decks are generally in an eccentrically loaded state for the nonuniformly distributed wheel loads. By conducting numerical simulation and fatigue tests of components stiffened by the vertical rib (CVR) with single butt weld, the propagation law of CVR cracks under eccentric loading were analyzed. By comparing with components stiffened by U-ribs (CUR), the difference of crack-growth characteristics between components with single and multi butt welds under eccentric loading was explored. The results show that CVR cracks will initiate at the eccentrically loaded side of the weld and propagate obliquely, but still perform the bilateral cracking mode as that under symmetric loading. The CUR and CVR cracks present the same three-stage characteristics of fast-slow-rapid growth and components will accelerate to failure in the third stage, which shall be avoided. The section-damage rate of CUR will be greatly relieved for the unilateral cracking under eccentric loading compared with that of bilateral cracking under symmetric loading, which delays the crack to enter the rapid-growth stage. Since there’s little effect of eccentric loading on the demarcations of crack-growth stages in CVR, it is reasonable to take the demarcation 80 mm between the second and third crack-growth stages as the warning length for maintenance. The semi-elliptical CVR cracks will quickly penetrate base metal after extending to 75 % of thickness with the average ratio of crack depth to length being 0.09, which can be treated as the operation timing of maintenance methods for non-penetrating cracks.

Finite Element Analysis and Reinforcement of Steel Crane Beam under Eccentric Track Loading

The crane track of a steel structure workshop was installed eccentrically, and the crane operation caused a large deflection of the crane beam, requiring reinforcement measures. The finite element model of the crane beam was established by Midas Gen finite element software, and the maximum stress, deflection, and the stress amplitude of 9 m and 12 m steel crane beam under different track eccentricity values were analyzed. The results show that when there is no brake truss, the maximum stress and deflection of the crane beam will increase greatly under the action of eccentric loading. On the contrary, a brake truss can effectively reduce the adverse effect of eccentric loading; the fatigue strength of crane beam cannot be controlled under eccentric rail loading. The reason why steel crane beam is sensitive to track eccentricity is that its torsional stiffness is too small. As a reinforcement measure, welding angle steel or steel plate lower on the crane beam flange, forming a box section, can effectively increase the torsional stiffness of the crane beam; the residual stress can then be effectively reduced by applying intermittent welding and reinforcement using the same material.

Numerical investigation on behaviour of castellated steel beam in lateral distortional buckling

The construction sector makes extensive use of steel because of its flexibility, corrosion resistance, and lightweight. Castellated I-shaped steel beams have a more comprehensive range of applications than typical type steel beams. Castellation ensures that structural stability is improved and can be used in steel structures. Previous investigations have shown that lateral distortional buckling (LDB) is the primary cause of apparent failure in castellated steel beams. Here in this study, a numerical investigation was carried out using a finite element model developed in commercial software ABAQUS®. Then using a validated numerical model, parametric studies were conducted. The effect of eccentric loading, the partition of web castellation, and the effect on lateral distortional buckling (LDB) failure mode under vertical stiffener in the web are evaluated. The present study shows that LDB exists in the case of eccentric loading and web partitions. Eccentric loading led to a 5% decrease in ultimate load capacity. The addition of web partition enhanced the ultimate load-carry capacity by 7%. Higher load capacity was observed for specimens with vertical stiffeners, which helps mitigate lateral distortional buckling of castellated steel beams.

Study on fracture behavior for sharp V-notched specimens combined with 3D-DIC and caustics

In this paper, the fracture behavior of Three-Point Bending (TPB) beams with V-notch under mode I and mixed mode I-II loading is investigated. For this purpose, first, an experimental system combining three-dimensional digital image correlation (3D-DIC) and a new digital laser caustic is established. Then, based on displacement field for V-notch and the displacement extrapolation theory, a new method (3D-DIC) for measuring Notch Stress Intensity Factors (NSIFs) of V-notches under mixed mode loading is presented and verified. Furthermore, based on the established system, the effect of eccentric loading and the rotation angle of V-notches on the initiation and propagation for V-notch is analysed, and the SIF results for V-notched specimen from initiation to crack arrest are provided. Obtained results demonstrate that SIF increases rapidly at first, and then decreases with the decrease of energy at the initial stage of notch propagation. Under the action of eccentric load, V-notches initiate and propagate toward the load position. In addition, the values of mode I NSIFs (KIV) and the length of failure time of these specimens are ranked as: specimen B (notch rotation angle of 0°) > specimen D (notch rotation angle of −60°) > specimen C (notch rotation angle of 60°). However, the absolute value of mode II NSIFs (KIIV) and the distance of crack arrest in X direction of these specimens are ranked as: specimen C > specimen D > specimen B. Finally, the Maximum Tensile Stress (MTS) criterion suitable for V-notches under mode I or mixed mode loading is proposed, and the validity of the criterion is verified by experimental results.

Evolution mechanism of active soil arching in a shallow trapdoor under eccentric loading

This study provides insight into the effect of eccentric loading on soil arching. A numerical trapdoor model was developed using the discrete element method to investigate the evolution mechanism by considering the magnitude of the surcharge and the deviation distance. The parameters were validated using laboratory results. The numerical results showed that the Ground reaction curve (GRC) on the trapdoor could be divided into two categories. GRC type I included stages of initial soil arching, maximum soil arching, load recovery, and an ultimate stage. For GRC type II, the ultimate stage was replaced by a declining stage. The minimum soil arching ratio increased with the increasing surcharge, but decreased with the increasing deviation distance within 0.75B (B is the trapdoor width). The vertical displacement field inclined as the load deviated from the centered position, transforming from a trapezoid to a quadrilateral. The soil arching effect was degraded by the surcharge.

Determination of the stability of residual pillars in a room-and-pillar mining goaf under eccentric load

In room-and-pillar mining (RPM), the roof of a coal seam is supported by coal pillars; however, the roof is non-uniformly deformed with time. Moreover, coal pillars at different positions are subjected to different stresses and some coal pillars are prone to the effects of eccentric load, thus influencing their stability. Therefore, by taking Bandingliang Coal Mine, Shaanxi Province, China, as the engineering background, the non-uniform deformation characteristics of the roof of a room-and-pillar mining goaf (RPMG) were first analysed by using numerical simulation and theoretical analysis. The residual pillars in the RPMG were partitioned into a uniform deformation zone, a transition zone, and a sub-uniform deformation zone; thereafter, the stress distribution in coal pillars under non-uniform deformation was revealed to show that coal pillars were subjected to non-uniform stresses; subsequently, the distributed force under the eccentric load was concentrated to attain the changes in stress state of coal pillars under eccentric load, including behaviour such as a non-uniformly compressed state, critical state, and a tensile stress state; finally, the pillar stability under the eccentric load was judged by taking the No. 19 coal pillar as an example. The result showed that the shear stress generated by the coal pillar was 0.58 MPa, which was lower than the allowable shear stress (1.51 MPa). As a result, the pillar did not collapse, consistent with actual conditions on site. The result is expected to provide a theoretical basis for controlling pillar stability in the RPMG. The theory of the stability of the residual pillars in the RPMG provided in this paper provides a new direction for determining the stability of pillars, and the study findings have been applied in specific mines and verified.

Behavior of RC Wide Beams under Eccentric Loading

Wide beams are one of the widely used structural elements in RC buildings due to the many special features that characterize them. The main objective of this research is to investigate the behavior of wide shallow beams under the effect of eccentric loading acting along their cross sections. To achieve that, an experimental program that consisted of seven wide beams was conducted. All beams were loaded using two concentrated loads at their middle third where the main parameters considered were: the magnitude of the load eccentricity, the longitudinal spacing between shear reinforcement, and the arrangement of the longitudinal reinforcement. Following that, a finite element analysis was performed where the analytical model used was first verified using the data from the experimental program. The results from both the experimental and analytical programs were in good agreement. Then, the finite element analysis was extended through a parametric study where other variables were studies such as the compressive strength of concrete, the transverse spacing between stirrups and the longitudinal reinforcement ratio. The results showed that the value of the load eccentricity, spacing between shear reinforcement, the arrangement of the main reinforcement along the beam cross section, and the compressive strength of concrete significantly affected the torsional resistance of shallow wide beams. Conclusions and recommendations are presented which can be useful for future researchers. Doi: 10.28991/cej-2021-03091766 Full Text: PDF

Low cycle fracture behavior of steel members with circular hollow section subjected to eccentric load

This study aims to investigate the effect of eccentric load on the seismic and fracture behavior of Q235B steel members with circular hollow section (CHS). To this end, uniaxial tension and ultra-low cycle fatigue tests on both un-notched and notched Q235B steel coupon specimens were conducted first to evaluate the material’s micromechanical fracture behavior. Next, 7 full-scale Q235B CHS steel members with different global slenderness were tested under cyclic axial loads with varying eccentricities. It is observed that: (1) the increase of the eccentricity of the axial load negatively affects the seismic and fracture resistance of CHS steel members, resulting in the deterioration of the strength, stiffness, energy dissipation, and ductility; (2) Large eccentricities lead to the reduction in the fracture life of Q235B CHS steel members; and (3) High global slenderness results in the reduction in both compression bearing capacity and energy dissipation of CHS steel members. In addition to the experimental program, finite element analyses are performed to simulate the seismic and fracture behavior of CHS steel members. The results from the finite element analyses are in good agreement with those from the experiment.

Structural behaviour of tyre-bale sandwich wall under axial load

This paper presents structural behaviour of tyre-bale sandwich wall that is made of two outer reinforced concrete walls and tyre-bale as core material. The thickness of tyre-bale and each concrete wall is 650 mm and 125 mm respectively. The concrete walls are reinforced with 6 mm diameter steel bars in each direction. Four sandwich walls were casted and tested on full scale under different compression loadings. In the first test, the axial load was applied directly to the tyre-bale to investigate the tyre-bale compressibility. The effect of eccentric loading was studied in the second test by applying the compression load on one concrete wall. In the third test, load was applied simultaneously on both concrete walls and finally, the fourth compression test was conducted by cutting-off the tie wires to simulate the severe corrosion conditions. The structural behaviour of sandwich wall is discussed in terms of ultimate load, vertical and lateral deflections, strain distribution and failure mechanism. In addition, the change in structural behaviour of sandwich wall under the effect of severe corrosion is presented. A significant reduction in structural capacity of sandwich wall was observed, when simulating corrosion conditions. Finite element modeling (FEM) of the sandwich wall was conducted in ABAQUS to simulate the damage of concrete in compression using concrete damage plasticity model. The difference in experimental and FEM results was found to be 15%. Furthermore, the experimental peak loads are compared with the existing empirical equations, which provided conservative design values to estimate the ultimate design load of sandwich wall.

Study on Seepage Characteristics of Composite Bucket Foundation Under Eccentric Load

Under the effect of eccentric loads, when the suction pressure of the composite bucket foundation is leveled, the seepage failure is very easy to occur. The seepage failure occurrence causes the foundation to settle unevenly and impairs the bearing performance. This study uses ABAQUS finite element software to establish a composite bucket foundation model for finite element analysis. The model simulates the seepage of the foundation penetrating process under eccentric load to reveal the induced seepage characteristics of the bucket foundation. The most vulnerable position of seepage failure under the eccentric loading is elucidated. Critical suction formulas for different offset eccentric moment strategies are derived and compared with existing literature formulas. Then the derived formula is supplemented and corrected according to the pressure difference between adjacent cabins. Conclusions can be drawn: (1) Under eccentric loads, the critical suction decreases about 7%–10%. (2) The pressure difference between adjacent cabins impacts significantly on the seepage field, and the critical suction, at most, can be reduced by 17.56%. (3) the offset strategies have little effect on the seepage field. Efficient and appropriate strategies can be selected to meet the requirement of leveling in engineering project.

Behaviours of Ring and Circular Footings Subjected to Eccentric Loading: a comparative Study

This study experimentally examined the behaviours of ring and circular footings resting on loose sand overlying dense sand based on the application of eccentric loads with eccentricity values of 0, 4, 8, and 16 mm. Many researchers have examined the effects of concentrated loads on ring footings numerically; however, few studies have taken into account the effect of eccentric loads on ring footings on loose and dense sand, and even fewer have done so experimentally. This paper thus presents the experimental work done to understand and make comparisons between circular and ring footings under such circumstances. The results of the tests indicate that there is a significant increase in the bearing capacity and a decrease in the settlement of ring footings in comparison with circular footings under the same conditions. Further, ring footings offer approximately the same behaviours as circular footings with respect to eccentric loads. These results indicate that the use of ring footings rather than circular footing can provide improved structural performance at low cost.

Stability and load-carrying capacity of short composite Z-profiles under eccentric compression

This study investigates the problems of non-linear stability and load-carrying capacity of thin-walled composite Z-profiles under compression. The primary objective of the study was to determine the effect of eccentric load and ply-stacking sequence on the post-critical behaviour and load-carrying capacity of the analysed structures. Experimental and numerical methods were employed, which made it possible to describe structural performance of the analysed composite structures over the full range of loading, including the description of composite material damage. Experimental tests were performed on the physical models of CFRP profiles made by autoclaving. The real structures were subjected to compression until a complete loss of their load-carrying capacity. Simultaneously, numerical calculations were performed by the finite element method. The progressive damage model was used to evaluate the degree of damage in the composite material. The developed numerical models were validated with the results of experimental tests.

Surrogate Neural Network Model for Prediction of Load-Bearing Capacity of CFSS Members Considering Loading Eccentricity

In this study, a surrogate Machine Learning (ML)-based model was developed, to predict the load-bearing capacity (LBC) of concrete-filled steel square hollow section (CFSS) members, considering loading eccentricity. The proposed Artificial Neural Network (ANN) model was trained and validated against experimental data using the following error measurement criteria: coefficient of determination (R2), slope of regression, root mean square error (RMSE) and mean absolute error (MAE). A parametric study was conducted to calibrate the parameters of the ANN model, including the number of neurons, activation function, cost function and training algorithm, respectively. The results showed that the ANN model can provide reliable and effective prediction of LBC (R2 = 0.975, Slope = 0.975, RMSE = 294.424 kN and MAE = 191.878 kN). Sensitivity analysis showed that the geometric parameters of the steel tube (width and thickness) and the compressive strength of concrete were the most important variables. Finally, the effect of eccentric loading on the LBC of CFSS members is presented and discussed, showing that the ANN model can assist in the creation of continuous LBC maps, within the ranges of input variables adopted in this study.