Increasing Displacement Amplitude Research Articles

The influences of normal load and displacement amplitude on fretting wear behavior of M50 bearing steel

This study aims to obtain key parameters such as the fretting wear coefficient and wear rate of M50 bearing steel through fretting wear experiments. By integrating the Umeshmotion subroutine, a validated 3D ball-plane energy dissipation fretting wear model was established. The research explores wear behavior and transition mechanisms under different normal loads and displacement amplitudes. Experimental and finite element analyses show that fretting wear rate is negatively correlated with normal load and positively correlated with displacement amplitude. These variables influence contact stress, shear stress, and slip distance, affecting wear morphology. Results indicate that increasing normal load transitions fretting wear from gross slip to partial slip, while increasing displacement amplitude shifts it from partial slip to gross slip.

Cyclic shear behavior and BoBiLSTM-based model for soil-rock mixture-concrete interfaces

In order to study the impact of surface roughness on the cyclic shear characteristics of the Soil-Rock Mixture and concrete interface, a series of cyclic shear tests were conducted using a large indoor direct shear apparatus. The effects of three concrete surface roughness coefficients JRC (0.4, 9.5, 16.7), five rock content levels (0%, 25%, 50%, 75%, 100%), and three cyclic shear displacement amplitudes (1, 3, 6 mm) on interface cyclic shear stress and Soil-Rock Mixture shear deformation were analyzed. A Bidirectional Long Short-Term Memory (BoBiLSTM) model was proposed, utilizing Bayesian optimization and k-fold cross-validation for hyperparameter tuning to streamline the model parameter selection process and enhance the prediction accuracy of the stress-strain relationship under cyclic loading. The experimental results show that, under five rock content levels, as the concrete surface roughness coefficient and cyclic shear displacement amplitude increase, the interface average peak shear stress increases accordingly. The interface average peak shear stress of the sample with 75% rock content is the highest; in terms of vertical displacement, the sample with 50% rock content has the maximum displacement, while the sample with 25% rock content has the minimum. The two types of samples show different soil deformation patterns in the two shear directions during the cyclic shearing process; as the shear displacement amplitude increases from 1 mm to 3 mm and 6 mm, the greater the concrete surface roughness, the smaller the change in shear stiffness and damping ratio. Compared to traditional Long Short-Term Memory (LSTM) models, the BoBiLSTM model demonstrated improvements in the average metrics of R2, RMSE, and MAPE by 0.32%, 57.25%, and 72.32%, respectively.

Bearing and deformation characteristics of monopile foundation under monotonic and cyclic horizontal loads.

The bearing and deformation characteristics of monopile foundation under the monotonic and cyclic loads are key factors to consider in the design of the transmission tower structure or offshore wind energy converters. The model tests and numerical simulations of monopile foundation under monotonic and cyclic horizontal loads were performed in sand to explore the bearing characteristics and the deformation characteristics of pile. The potentially affected factors including loading height, relative density of soil, displacement amplitude were analyzed. The results show that with the loading height varies from 1D to 4D, the horizontal static bearing capacity of the pile under different the soil relative density decreased by 1.63-1.9 times, and the peak bending moment increased by 22.9%-36.8%. Under the cyclic loads, the peak load on the pile top increased by 31.7%-56.1% for each 1 mm increase in displacement amplitude. The stiffness of soil around pile varies as the number of cycles increases with the development trend of decreases first and then increases gradually. As the horizontal load and cycle number increase, the range of the displacement of soil extends towards the bottom of pile, until it covers the entire lower part of the model.

Digital Image Correlation Structural Strain Analysis of S235 Fillet-Welded Joints under Low-Cycle Fatigue Loadings

The main objectives of the present study were the application and validation of the newly proposed Digital Image Correlation equivalent structural strain approach for assessing the low-cycle fatigue life of S235 welded joints. Low-cycle fatigue tests were performed at a displacement ratio of minus one. Experimental tests were performed using two different ways of controlling the displacement amplitude: applying traditional low-cycle fatigue tests at a constant amplitude and stepwise succession tests at increasing amplitudes. A comprehensive, independent experimental procedure, proposed by the authors and not yet validated for steel welded joints, was applied to assess the equivalent structural strain range using the Digital Image Correlation technique for the traditional low-cycle fatigue tests and stepwise succession tests at increasing amplitudes. It is noteworthy that the values of the DIC equivalent structural strain (ΔEs from the DIC), calculated on the external sides of the samples, were utilized to predict fatigue life in correlation with the ASME mean curve and fall within the ±3σ scatter bands (external bands). In particular, most of the tests lie within the ±2σ boundary of the design curves except for some tests at low applied displacements. Moreover, it was shown that this method is applicable to stepwise succession tests with increasing displacement amplitudes, leading to significant time savings compared to conventional experimental tests.

Prediction of contact resistance of electrical contact wear using different machine learning algorithms

H62 brass material is one of the important materials in the process of electrical energy transmission and signal transmission, and has excellent performance in all aspects. Since the wear behavior of electrical contact pairs is particularly complex when they are in service, we evaluated the effects of load, sliding velocity, displacement amplitude, current intensity, and surface roughness on the changes in contact resistance. Machine learning (ML) algorithms were used to predict the electrical contact performance of different factors after wear to determine the correlation between different factors and contact resistance. Random forest (RF), support vector regression (SVR) and BP neural network (BPNN) algorithms were used to establish RF, SVR and BPNN models, respectively, and the experimental data were trained and tested. It was proved that BP neural network model could better predict the stable mean resistance of H62 brass alloy after wear. Characteristic analysis shows that the load and current have great influence on the predicted electrical contact properties. The wear behavior of electrical contacts is influenced by factors such as load, sliding speed, displacement amplitude, current intensity, and surface roughness during operation. Machine learning algorithms can predict the electrical contact performance after wear caused by these factors. Experimental results indicate that an increase in load, current, and surface roughness leads to a decrease in stable mean resistance, while an increase in displacement amplitude and frequency results in an increase in stable mean resistance, leading to a decline in electrical contact performance. To reduce testing time and costs and quickly obtain the electrical contact performance of H62 brass alloy after wear caused by different factors, three algorithms (random forest (RF), support vector regression (SVR), and BP neural network (BPNN)) were used to train and test experimental results, resulting in a machine learning model suitable for predicting the stable mean resistance of H62 brass alloy after wear. The prediction results showed that the BPNN model performed better in predicting the electrical contact performance compared to the RF and SVR models.

Acoustic streaming and cavitation effect on microstructure evolution of Nb-Si-Ti alloy treated by ultrasound

Heat and mass transfer play a critical role in grain refinement by ultrasound treatment. In order to reveal the mechanism of ultrasonic in Nb-Si molten metal, a 3-D model was simulated on the acoustic, temperature and flow fields with different acoustic frequencies and displacement amplitudes by Comsol Multiphysics. Simulation results show that a new harmonic wave appears with frequency increasing, and the acoustic streaming effect is significant at 20 kHz. As the displacement amplitude increases from 10 μm to 20 μm, the maximum velocity varies from 0.01 m/s to 0.03 m/s. The distributions of three fields are dependent on frequency, and the displacement amplitude determines acoustic pressure value and fluid velocity. The displacement amplitude has a positive effect on the acoustic streaming effect improvement in the melt. In the UST ingots with different displacement amplitudes, the size of the broken dendrites decreases from 57.5 μm to 10 μm with the displacement amplitude lower than 16 μm, by 82.6%. γ-Nb5Si3 phase increases and the primary Nbss phases are elongated, coarsened and spheroidized with the increase of the displacement amplitudes. The simulation results of the flow directions can be verified by the elongated Nbss phase. The acoustic streaming effect promotes heat and mass transfer and the sluggish eutectoid reaction in Nb-Si-Ti alloy during the ultrasound treatment.

The vibration energy dissipation behaviour of 3D-PAM type RVD

Considering that ordinary rubber materials have problems such as insufficient mechanical properties and poor shock absorption effect, a right-angle viscoelastic damper (RVD) based on 3D printed auxetic metamaterial (3D-PAM) is proposed in this paper. According to the refined finite element simulation, a dynamic energy dissipation study was conducted on the RVD. Firstly, the 3D-PAM was fabricated by selective laser sintering printing technique, and its material properties were demonstrated. Secondly, the 3D-PAM type RVD was simulated by ABAQUS to study the characteristics of dynamic energy dissipation and to investigate the stress distribution and displacement variation of the 3D-PAM layer. The results show that the hysteresis curve shape is smooth and full under all working conditions. The hysteresis loop shows linear characteristics under small displacement amplitude. As displacement amplitude increases, a hardening nonlinear response is observed. The maximum loss factor of the 3D-PAM type RVD reaches 0.64. Under the same thickness and loading conditions, the maximum loss factor has increased by 16.4% and 100.0% respectively compared to Polyurethane type RVD and Fluororubber type RVD. In conclusion, results indicate that the 3D-PAM type RVD designed in this project exhibits superior energy dissipation characteristics.

Experimental and numerical investigations on adaptive stiffness double friction pendulum systems for seismic protection of bridges

This study examines the design, development, and characterization of double friction pendulum systems with variable sliding surface geometry. The proposed isolator has a spherical surface with a small radius within an inner sliding range while different geometric functions are used to describe the sliding surface in the outer range. As a result of variable curvature used as sliding surface, the isolators exhibit an adaptive stiffness behavior with increasing displacement amplitude. First, the analytical equations that describe the characteristics of the proposed isolators were derived. Then, a large-scale prototype adaptive isolator that employs a logarithmic function for the sliding surface geometry in the outer range was fabricated. The response of the prototype isolator was characterized under increasing amplitude reversible cyclic loads considering two different levels of vertical isolator loads. A high-fidelity finite element model was developed to capture the response of the prototype isolator. The results obtained from the experimental tests and numerical simulations were used to verify the analytical equations derived for the proposed isolators. Next, a typical multi-span bridge structure was modeled with adaptive stiffness isolators and its response under bi-directional ground motions records were analyzed. In contrast to a conventional double friction pendulum bearing, the suggested isolators yield significantly reduced base shear forces while exhibiting greater isolator displacements. However, the proposed isolators retain the capability to effectively curtail excessive displacements, ensuring the prevention of collapse.

Effect of cyclic loading on the mobilization of unit base resistance of model piles jacked in sand

This paper reports the results of a series of monotonic compressive and cyclic load tests performed on a closed-ended jacked model pile installed in a half-cylindrical calibration chamber with image analysis capabilities. The monotonic compressive load tests were carried out before and after performing a displacement-controlled cyclic load test to determine the impact of cycling on unit base resistance. Digital images of the sand and the model pile were taken during cyclic loading and processed using the digital image correlation (DIC) technique to obtain the cumulative displacement and strain fields in the sand domain. The results show that the ultimate unit base resistance can drop significantly after cycling. The magnitude of the drop in ultimate unit base resistance depends on both the magnitude of the cyclic displacement amplitude and the number of cycles. However, the unit base resistance at plunging increases after large-displacement half-amplitude cycling. The increase in unit base resistance at plunging after cycling is linked to the flow of sand particles to the zone below the conical base, the occurrence of sand particle crushing, and the dilative behavior of the sand outside a bulb of crushed particles formed during cyclic loading. The processed DIC data show that for cyclic displacement half-amplitudes ∆wcyclic less than or equal to 0.25 mm (0.0007B), the cumulative radial and vertical displacements in the soil domain normalized by ∆wcyclic are negligible. Values of ∆wcyclic greater than 0.25 mm produce normalized displacements in the soil domain that increase as the cyclic displacement amplitude increases.

Mechanism of wear in zircaloy-4 under different loading conditions

Core components of nuclear reactor are generally made of zirconium alloys and some of them are prone to low amplitude vibration leading to material wear at contact interface. Reciprocating wear tests were conducted between zircaloy-4 (Zr-4) under dry and water-submerged conditions. To confirm the material transfer due to adhesion, wear tests were also conducted between Zr-4 and stainless steel. To understand the wear mechanism, worn surfaces were analyzed using scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). Coefficient of friction (COF) increases with increasing fretting duration and decreases with increasing frequency and displacement amplitude. Greater COF is observed under dry condition than that under submerged condition. The wear mechanism changes from adhesion to abrasion with increasing displacement amplitude.

Behavior of anchorage narrow mechanically stabilized earth walls under seismic loading

The rapid increasing and development of infra-structures in Egypt in very limited spaces involves construction of Narrow Mechanically Stabilized Earth (NMSE) walls having an aspect ratio (ratio of reinforcement length, L, to wall height, H) below 0.70. These walls are constructed Infront of existing rigid faces and the top reinforcement layer is fixed to the face by mechanical connections. These walls are subjected to dynamic loads when constructed in active seismically areas. The purpose of this paper is to present a typical -one- reduced scale (1/8 of the prototype model) shaking table test of (L/H) equal 0.30. The model is shaken using stepped sinusoidal base accelerations with incrementally increasing displacement amplitude and constant frequencies to generate an equivalent base acceleration ranging from 0.05 g to 0.80 g or until failure occurs. The frequency of the wave is 2.50 Hz. The results of the tests displays that the yield acceleration of the tested wall is about 0.48g. The results of NMSE walls with reinforcement anchorage resulted in yield acceleration higher than 26 % when correlated to the published NMSE walls without reinforcement anchorage. Finally, 1.25 average amplification factor can be used in the seismic design of NMSE walls of similar configurations.

A restoring force model for frames with steel tube columns filled with recycled aggregate concrete

AbstractTo establish a restoring force model for recycled aggregate concrete‐filled steel tube (RACFST) frames, the quasistatic tests on two frames comprising two RACFST columns and a reinforced recycled aggregate concrete (RRAC) beam each was carried out. The recycled coarse aggregate replacement ratio was 100%. The failure mechanism, hysteretic curves, and strain response of the specimens were discussed. By analyzing the degradation of the load bearing capacity with increasing displacement amplitude and combining the hysteretic curves and stiffness degradation relationships, a restoring force model of load versus displacement adopting a trilinear approximation was proposed. The characteristic points of the model were the relative yield point, relative peak point, and relative failure point. Results showed that bending‐shear or bending failure occurred at the ends of specimen beams and plastic hinges formed there earlier than at the column ends. The hysteretic curves of load versus displacement were essentially symmetric in a full shuttle shape. The proposed restoring force model adopting trilinear approximation agreed well with the experimental hysteretic curves under low‐cycle loading and can thus be recommended to perform the elastoplastic analysis of seismic response for this new type of composite structures.

The Effect of Displacement Amplitude on Fretting Wear Behavior and Damage Mechanism of Alloy 690 in Different Gaseous Atmospheres.

The effect of displacement amplitude on fretting wear behavior and damage mechanisms of alloy 690 in air and nitrogen atmospheres was investigated in detail. The results showed that in air, the friction coefficient gradually increased with the increase in displacement amplitude which conformed to the universal law. In nitrogen, however, it had the highest point at the displacement amplitude of 60 μm due to very strong adhesion. Whether in air or nitrogen, the wear volume gradually increased with the increase in displacement amplitude. The wear volume in air was larger than that in nitrogen except at 30 μm. At 30 μm, the wear volume in air was slightly smaller. With an increase in displacement amplitude, a transformation of fretting running status between partial slip, mixed stick-slip, and final gross slip occurred along with the change of Ft-D curves from linear, to elliptic, to, finally, parallelogrammical. Correspondingly, the fretting regime changed from a partial slip regime to a mixed regime to a gross slip regime. With the increase in displacement amplitude, the transition from partial slip to gross slip in nitrogen was delayed as compared with in air due to the strong adhesion actuated by low oxygen content in a reducing environment. Whether in air or nitrogen, the competitive relation between fretting-induced fatigue and fretting-induced wear was prominent. The cracking velocity was more rapid than the wear. Fretting-induced fatigue dominated at 30 μm in air but at 30–60 μm in nitrogen. Fretting-induced wear won the competition at 45–90 μm in air but at 75–90 μm in nitrogen.

Investigation on fretting wear of Al-Li alloy

PurposeThis paper aims to investigate the fretting wear mechanism of an Al-Li alloy at room temperature, the tangential fretting wear tests were carried out.Design/methodology/approachThe effects of displacement amplitude and fretting frequency on the tangential fretting wear characteristics were mainly investigated. The experimental data obtained are analyzed and compared.FindingsThe results indicated that the fretting friction coefficient increased with the increase of displacement amplitude. As the displacement amplitude increased, the wear scar morphology changed significantly, mainly in terms of delamination debris and furrow scratches. The wear mechanism changed from initial mild wear to more severe oxidative wear, adhesive wear and abrasive wear.Originality/valueThis paper extends the knowledge into mechanical tight connections. The conclusions can provide theoretical guidance for the fretting of mechanical tight connections in the field of automotive lightweight and aerospace.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-11-2019-0490/

Steel tubular friction damper and vibration reduction effects of double-layer reticulated shells

A steel tubular friction damper (STFD) is proposed for vibration reduction in large-span spatial structures. The effects of the amplitude of the applied displacement, the pre-tightening force of the high-strength bolts, and the material of the friction plates on the hysteretic behaviour of the STFD are analysed experimentally. The single-cycle energy consumption increases and the equivalent stiffness decreases with increasing displacement amplitude. In addition, the single-cycle energy consumption and equivalent stiffness of the STFD increase with increasing pre-tightening force. Both the single-cycle energy consumption and the equivalent stiffness of the STFD with aluminium alloy or brass friction plates are larger than that of the STFD with steel friction plates. Then, a mechanical model of the STFD is established for further numerical analysis. Several structural members in a 40-m-span double-layer reticulated shell are replaced with STFDs to provide vibration reduction. Optimal arrangement of STFDs is studied based on additional modal damping ratio. The effects of the replacement rate, earthquake intensity and various ground motions on the vibration reduction effect are investigated via numerical analyses. The reduction ratio first increases and then decreases with increasing replacement rate, and the best performance is observed at a replacement rate of 10%. The vibration reduction effect of the STFDs is more obvious for strong ground motions than for weak ground motions. Under various ground motions, the vibration reduction effect of the STFDs is better for the two ordinary ground motions than for the four long-period ground motions selected herein.

Analytical study on controlled lateral thermal buckling of antisymmetric mode for subsea pipelines triggered by sleepers

Subsea pipelines exposed to high temperature and high pressure (HTHP) conditions is susceptible to lateral buckling. In order to control lateral buckling, engineered buckle initiators, such as sleepers, are introduced to initiate planned lateral buckles along the pipeline at specific locations in order to ensure that the stress in each lateral buckle remains acceptable. In this study, taking the interaction of adjacent buckles into account, analytical solutions of antisymmetric lateral buckling mode triggered by sleepers are derived. With the proposed formulations, the method to obtain the accurate locations of lateral displacement amplitude and maxima of bending stress is presented and discussed. And a detailed comparison between symmetric and antisymmetric mode of lateral buckling triggered by single sleeper is presented. Moreover, the influence of the sleeper spacing on controlled lateral buckling behaviour with the consideration of axial interaction between adjacent buckles is conducted. Finally, a detailed analysis about the influence of the sleeper height, lateral frictional coefficient and submerged weight of the pipeline on the controlled post-buckling behaviour is presented. Our results show that, for smaller sleeper friction or smaller sleeper height, the symmetric mode is more likely to happen, while the antisymmetric mode is prone to occur for larger sleeper friction and larger sleeper height. One effective method to reduce displacement amplitude and maximum stress is to decrease the sleeper spacing. The minimum critical temperature difference decreases with increasing sleeper height and increases with increasing lateral friction coefficient or submerged weight of the pipeline. And an alternative way to reduce the maximum stress is to reduce the lateral friction coefficient or submerged weight of the pipeline even though the displacement amplitude increases.

Behaviour of the interface between stored wheat and a steel silo under static and cyclic loading conditions

The interface behaviour between the steel surfaces of a silo and the grains wheat stored within plays a decisive role in the design of the structure of the silo. A series of strain-controlled direct shear tests, including monotonic loading, cyclic loading and post-cyclic loading were used to study the behaviour of the wheat-steel interface behaviour. The influence of cycle numbers, shear displacement amplitude, normal stress and initial void ratio on the behaviour of the interface behaviour are examined in detail. It was observed that the cyclic loading results in an increasing peak strength, internal friction angle and apparent cohesion, whereas decreasing interface contraction deformation occurs. The results show that the values of peak stress increase with increasing displacement amplitude and cycles, and they change slightly after 10 cycles. The interface exhibits overall contraction, while the contraction is suppressed by an alternating small dilation during cyclic loading. The ultimate peak shear strength increases with increasing normal stress and decreasing initial void ratio. During the tests, the interfaces displayed larger contraction at higher normal stresses and initial void ratios. These findings provide useful information for the analysis of the wheat-steel interface behaviour during both static and cyclic loading conditions.

Accumulated Damage-based Experimental Study on Seismic Performance of HRBF500 Rebar Reinforced RC Bridge Columns

The evolution of the damage and seismic behaviour of the reinforcement concrete (RC) bridge columns reinforced with HRBF500 rebar was investigated in this paper. Nine bridge column specimens with various strengths of longitudinal reinforcement, reinforcement ratios, axial compression ratios and stirrup ratios were tested under horizontal cyclic loading. The influences of the designed parameters of the mechanical properties such as failure mode, loading-displacement curve, skeleton curve, strength and stiffness degradation and energy dissipation were analysed in the view of damage. There are four conclusions brought by the tested results. The damage process of specimens could be divided into turn-crack development stage, damage accumulation stage and failure stage. The damage will accumulate gradually and the strength and stiffness will also be degenerated, resulting in lower ductility and energy dissipation capacity of the specimens, as the displacement amplitude increases. The failure modes are similar, with plastic hinges occurrence varying from 30 to 260 mm above the concrete bases, accompanied by the steel buckling, fractured and the concrete local crushing. The good ductility and energy dissipation capacity of the HRBF500 reinforced concrete bridge columns are illustrated by the relatively plumper shuttle-shaped hysteresis curves obtained. The damage development was faster and energy was comparably larger of the specimens under the variation of displacement amplitude cycle loading, comparing with the constant displacement amplitude cycle loading. The bearing capacity of the specimens will be certain influenced by the increased reinforcement ratios and the larger energy dissipation capacity, with more longitudinal bars. The axial compression ratio also has an important influence on the damage development of the specimens. There are not considerable increments of bearing capacity, with the increment of reinforcement ratio, however, the ductility and energy dissipation ability will be improved obviously. The laws of damage development analysed by the experimental results were shown in this paper. The seismic damage assessment and seismic damage model of this kind of structural members were established by the experimental results above.

Histomorphometric Analysis of Callus Formation Stimulated by Axial Dynamisation in a Standardised Ovine Osteotomy Model.

The cyclic axial dynamisation of a stabilised fracture is intended to promote callus formation and bone healing. Most studies focused on biomechanical properties or the quantity of new bone formation. Far less is known about the quality of newly formed callus tissues, such as tissue distribution and arrangement within the callus. The aim of this current study was to investigate the effect of cyclic, axial dynamisation on the quantity and quality of callus in an established delayed fracture healing model. In 41 sheep transverse osteotomies with a gap size of 3 mm were stabilised with a unilateral external fixator. In 32 of these, fracture ends were axially stimulated with displacement amplitudes of 0.8 mm, 0.4 mm, 0.2 mm, or 0.0 mm, respectively, for six weeks. In the remaining 9 sheep of the control group, an additional external fixator was mounted to achieve almost total rigidity. Animal material originating from a past animal experiment was reanalysed in this study. Histological thin-ground sections were histomorphometrically analysed regarding the histological structure and composition of the defect region. A slight tendency towards an increase in size of total callus area, area of new bone (nB.Ar), and cartilage (Cg.Ar) was detected with increasing displacement amplitudes compared to the control group. At the anterior callus side nB.Ar and Cg.Ar were significantly larger than at the posterior side in all groups independent of treatment. Regarding the quality of callus, areas of very compact bone were predominant in the treatment groups whereas in the control group a slight shift to more porous bone was observed. No difference of callus compactness was observed between the anterior and the posterior side. The established method to assess the local compactness of callus areas is a useful tool to quantitatively determine the spatial distribution of new bone tissue within the callus. The application of this method in combination with biomechanical testing might reveal interesting relations between tissue distribution and bone strength that, with traditional histomorphometry, cannot be identified.

Shear Behavior of Wheat‐Concrete Interface during Monotonic and Cyclic Loading

The interface behavior between wheat and concrete plays a decisive role in the design of silo structures. In this paper, a series of strain‐controlled monotonic direct shear (MDS) tests, cyclic direct shear (CDS) tests, and postcyclic direct shear (PCDS) tests were conducted to investigate the wheat‐concrete interface behavior under monotonic and cyclic loading. The influence of cycle numbers, shear displacement amplitude, normal stress, and preloading consolidation was discussed in detail. In particular, the preloading consolidation simulates the partly discharging state of wheat. The values of peak stress increase with increasing displacement amplitude and cycles, and they change slightly after 10 cycles. The interface exhibits an overall contraction deformation during the MDS tests without preloading, but the contraction is suppressed by an alternating dilation during the DCS tests, and an overall small dilation occurs at small normal stress during PCDS tests. It is observed that the cyclic loading and preloading normal stresses result in an increasing peak strength, internal friction angle, and apparent cohesion, whereas a decrease in interface contraction deformation.