High Cyclic Loading Research Articles

Mechanical Characteristics of Sandstone under High Temperature and Cyclic Loading in Underground Coal Gasification

In the process of underground gasification of coal, the top rock of coal seam will experience a certain high temperature action and be in a complex stress environment. Therefore, it is of great theoretical and engineering significance to study the effect of cyclic unloading and loading on mechanical properties of rocks under high temperature action. In this thesis, the stress–strain curves of sandstone under different high-temperature treatments are obtained by conducting graded loading and unloading tests on sandstone treated at room temperature and at 200 °C, 400 °C, 600 °C, and 800 °C, respectively. The research content of this paper is as follows: the peak stress, peak strain, elastic modulus, Poisson’s ratio, internal friction angle, and cohesion of sandstone in the destruction stage of sandstone. The results show that the peak strain and cohesion of sandstone show an increasing trend with the increase of temperature from room temperature to 800 °C; the peak stress shows a decreasing trend with the increase of temperature from room temperature to 800 °C; the modulus of elasticity tends to increase from 200 °C to 400 °C and to decrease with temperature in the rest of the period; the Poisson’s ratio tends to increase from 600 °C to 800 °C and to decrease with temperature in the rest of the period; the internal friction angle increases sharply within room temperature to 200 °C, decreases slowly within 200–600 °C, and decreases sharply when the temperature exceeds 600 °C. The results of the study will provide important reference significance for the design and engineering application of the gasifier of a coal-bed underground gasification project.

Study on CO2 absorption-mineralization characteristics of mixed amine solution coupled with CaO and key influencing factors in mineralization process

Amine CO2 capture is an effective post-combustion carbon capture (PCC) technology, while CO2 mineral carbonation is a safe and stable method for CO2 storage. In this paper, these two methods were combined, and the CO2 absorption-mineralization performance of mixed amine solution coupled with CaO under different ratios of mixed amine solution, temperature, reaction time and CaO addition ratio were studied by using MEA/MDEA mixed amine solution as the CO2 absorbent and using CaO as the CO2 mineralizing raw material. The results show that CaO could effectively mineralize the CO2 absorbed in MEA/MDEA solution, realizing the regeneration of MEA/MDEA solution simultaneously under normal temperature and pressure. Meanwhile, the MEA/MDEA solution can still maintain a high CO2 conversion rate (77.4%) and CO2 cycle loading (1.03 mol/L) after five cycles of absorption-mineralization experiments. The FT-IR and XRD analyses reveal that the addition of CaO makes a large amount of Ca2+ and OH− into the MEA/MDEA solution, which could react with and protonated amine in the solution to form calcium carbonate precipitate and free amine respectively, thus realizing the mineralization of CO2 and the regeneration of MEA/MDEA solution. The main component of solid products obtained is calcium carbonate, and calcite is its main crystal form.

BUCKLING ANALYSIS AND MODAL ANALYSIS OF CONNECTING ROD USED IN I.C ENGINE

Every vehicle that uses an internal combustion engine requires at least one connecting rod depending upon the number ovf cylinders in the engine. It undergoes high cyclic loads of the order of 108 to109 cycles, which range from high compressive loads due to combustion, to high tensile loads due to inertia. Therefore, durability of the component is of critical importance. Due to these factors the connecting rod has been the topic of research for different aspects such as production, materials, performance simulation, etc. When designing a connecting rod, one needs to pay attention to the buckling strength of the rod. The buckling strength is heavily affected by the beam section, and Johnson's buckling equation is used to estimate the buckling strength of a given beam section. Finite Element Analysis (FEA) is often used to evaluate the buckling strength of a rod that has complex changes in beam section. we will also reinforce 2 mm layer of carbon fiber on shank length of connecting rod. Again, we will perform Finite Element Analysis on carbon fiber reinforce connecting rod for finding buckling strength.

Fatigue resistance of metal construction materials and its relationship with changes in the state of thin surface layers

The paper considers the proven clear relationship between the fatigue resistance of a number of structural materials and the processes occurring in their thin surface layers. The fatigue studies of the samples were carried out over a wide range of temperatures and amplitudes of cyclic stresses under uniaxial tension-compression with simultaneous microhardness measurement of the thickness of the hardened surface layer. On the basis of experimental studies of the fatigue of metallic structural materials, using the microhardness method, the regularities of hardening (softening) of their surface layer are established depending on the level of the amplitude of high-cycle loading and temperature. A method for the accelerated determination of the fatigue limit of structural materials based on the determination of microhardness during cyclic loading has been developed and tested. The dependence of the formed hardened film of the surface layer on the level of plasticity of the material has been established - the greater its plasticity, the thicker the resulting hardened film. With an increase in the amplitude of cyclic loading, the thickness of the hardened surface layer decreases.

A Deep Learning-Based Approach for the Identification of a Multi-Parameter BWBN Model

A restoring-force model is a versatile mathematical model that can describe the relationship between the restoring force and the deformation obtained from a large number of experiments. Over the past few decades, a large body of work on the development of restoring-force models has been reported in the literature. Under high intensity cyclic loadings or seismic excitations, reinforced concrete (RC) structures undergo a wide range of hysteretic deteriorations such as strength, stiffness and pinching degradations. These characteristic behaviors can be described by the multi-parameter Bouc-Wen-Baber-Noori (BWBN) model, which offers a wide range of applicability. This model has been applied for the response prediction and modeling restoring-force behavior in structural and mechanical engineering systems, by adjusting the distribution range of this model’s parameters. However, a major difficulty in utilizing the multi-parameter BWBN model is the parameters’ identification. In this paper, a deep neural network model is used to estimate the hysteresis parameters of the BWBN model. This model is one of the most versatile and widely used general hysteresis models that can describe the hysteretic behavior of RC columns. The experimental data of the RC columns used in this paper are collected from the database of the Pacific Earthquake Engineering Research Center (PEER). Firstly, the hysteretic loop obtained from a physical experiment is described by the BWBN model, and the parameters of the BWBN model are identified via a genetic optimization algorithm. Then a neural network is established by a backpropagation (BP) algorithm for associating the identified BWBN model parameters with physical parameters of the RC column. Finally, the regression analysis of the identified parameters is carried out to obtain the regression characteristics of the RC columns. The trained neural network model can directly identify the parameters of BWBN model based on the physical parameters of RC columns, and is effective and computationally efficient for multi-parameter BWBN model identification. The proposed approach overcomes the difficult problem of identifying the parameters of BWBN model and provides a promising approach for a wider application of this multi-parameter hysteresis model.

Diagnostic accuracy of a novel SARS CoV-2 rapid antigen test and usefulness of specimens collected from the anterior nasal cavity

ObjectivesWe aimed to validate a newly developed antigen-detecting rapid diagnostic test (Ag-RDT) for SARS-CoV-2 using anterior nasal specimens. MethodsBetween February 12 and September 30, 2021, 16 patients (age range, <1 month-76 years) were enrolled, and samples were collected simultaneously from anterior nasal and nasopharyngeal sites continuously during hospitalization. The primary end points were the diagnostic accuracy of the Ag-RDT and utility of anterior nasal specimens. ResultsIn total, 226 sets of paired samples were obtained. In 88.2% of specimens, the viral load was high at the nasopharyngeal site. The mean cycle threshold values for the anterior nasal and nasopharyngeal sites were 32.4 and 29.9, respectively. Using the real-time polymerase chain reaction results as a reference, the Ag-RDT showed a 100% sensitivity up to day 6 of the illness, using specimens with moderate or high viral load (cycle threshold <30) from either site. From day 7, the sensitivity was 70.4-90.6% and 83.9-84.6% for the anterior nasal and nasopharyngeal sites, respectively. The specificity remained at 100%. ConclusionOur novel Ag-RDT meets the World Health Organization criteria and provides stable sensitivity and specificity and accurate results with anterior nasal specimens.

Analyses of Damping Sustainability of Additively Manufactured Nickel Alloy Components Subjected to High Strain Loading Cycles

Abstract Integrally bladed rotors are more susceptible to vibration and high cycle fatigue failure. In response, damping treatments such as viscoelastic layers, hard coatings, and particle dampers have been utilized to reduce vibration of integrally bladed rotors and promote longer service life. In recent experiments, nickel-based alloy 718 structural beams representative of turbine blades were manufactured via laser powder bed fusion (LPBF) with internal geometries containing unfused powder. Compared to fully fused beams, these beams with internal particle dampers have demonstrated a significant improvement in damping performance, suppressing vibrations by as much as 95%. However, the inherent damping of the particle dampers decreases as the strain amplitude increases when some of the unfused powder fuses to the walls of the pockets. This study investigates the effect of the location of the particle dampers within the beam on the sustainability of its damping performance. The LPBF nickel-based alloy 718 beams are subjected to successive resonance dwells with increasing strain amplitude. After each dwell, the damping performance is assessed via the half-power bandwidth method of the frequency response function. Results from this study indicate that while the location of the particle dampers within the specimen does influence when the damping begins to degrade, it is not the optimal parameter for damping sustainability. The aim of this and future work is to improve the long-term damping performance and viability of the internal particle damper so that it can be more effectively utilized to extend the lifetime of turbomachinery components.

Energy-Efficient Biphasic Solvents for Industrial Carbon Capture: Role of Physical Solvents on CO2 Absorption and Phase Splitting.

Physical solvent is a promising alternative for the phase splitting of solvent to drastically reduce the regeneration energy during CO2 capture. Here, an aqueous biphasic solvent, optimally composed of 30 wt % polyamine (N, N-dimethylpropylamine, DMPA) and 50 wt % physical solvent (polyethyleneglycol dimethyl ether, NHD), is prepared, which presents high cyclic loading, low regeneration energy, and good stability. L16(45) orthogonal tests are performed to comprehensively evaluate the mass-transfer kinetics and the effect of crucial conditions, verifying the weak effect of NHD solvent on mass transfer. The solvent effect of NHD could decrease the energy barrier of carbamate generation from zwitterions (DMPA+COO-) to enhance chemical absorption. The low polarity of the NHD solvent provides source motivation and accelerates phase splitting. Time-space resolution distribution of CO2 capacity is established based on a scale-up separator with 5 L solvent, which supports multiscale force analysis for the various stages during phase splitting. The drag force of the homogeneous cluster was first introduced into separation dynamics, referred to as an important reason for the various splitting behaviors of a scale-up separator.

Self‐heating measurements under cyclic loading to identify history effects on HCF properties of high‐strength low‐alloy steel: Part II—Modeling

AbstractThe present paper proposes a new version of a model for high cycle fatigue of steels able to take load history effects into account. This model is developed in a probabilistic two‐scale framework. The proposed model accounts not only for the failure of samples under high cycle loadings but also for the thermal effects during cycling in a unified theoretical framework. Thus, an ad hoc identification procedure, essentially based on self‐heating tests under cyclic loadings provided in the accompanying paper, is proposed. The model was then validated by predicting the effect of a pre‐cycling loading on S‐N curves.

Adaptive modeling of vibrations and structural fatigue for analyzing crack propagation in a rotating system

This study is concerned with adaptive modeling of vibrations and structural fatigue in a rotating system with a propagating crack. The system consists of a Jeffcott rotor with a transverse surface crack at mid-span. It undergoes low and high cycle loadings due to an unbalance force. The high cycle loading (HCL) and the consequent high cycle fatigue (HCF) can accelerate crack growth, structural degradation and occurrence of mechanical failure. Therefore, accurate modeling is critical for lifetime prediction and prognostics requirements. There is a significant difference between the time constants of the rotor’s dynamic behavior and that of crack growth. Hence, in most of the prior studies, it has been assumed that the crack depth is constant, which implies that the system undergoes low cycle loading (LCL). In some studies that do focus on HCL, the loading scenario is assumed to be a summation of LCL steps with constant length. This study shows that assuming constant and pre-defined length for these steps can significantly affect the accuracy of the model leading to inaccurate lifetime prediction and poor prognostics in general. Hence, in this study, a novel approach is proposed in which the LCL step length is variable and adaptive. Considering different relationships proposed for modeling the fatigue crack growth, fluctuation of stress intensity factor (SIF) is the most important factor for driving the crack growth. Hence, an index is defined based on the rate of SIF fluctuation. Critical thresholds of this index are set at rapid and slow crack growth conditions. The level of proximity to these thresholds determines each LCL step length, which is hence determined adaptively. The equations governing the rotor motion and crack growth are formulated using Newton’s second law of motion and Paris–Erdogan’s fatigue crack growth law, respectively. The equations are solved numerically using the Runge–Kutta method. It is shown that this novel adaptive approach makes the modeling process realistic and computationally efficient while providing high accuracy. The results of this study could be of significance in decision making processes that would require lifetime prediction and prognostics of crack growth.

Ceramic-on-Ceramic Bearings in Total Joint Arthroplasty. Part 1

Summary. Ceramic bearings were first employed as alternatives to polyethylene (PE) bearings in total joint arthroplasty about a decade after Sir John Charnley introduced the first durable total hip arthroplasty (THA) with a metal-PE articulation. Charnley’s approach was based on a metal stem bonded to bone with polymethylmethacrylate (PMMA) and an acetabular component made of ultra-high-molecular-weight PE (UHMWPE). Microscopic particulate debris in the joint space from bearing wear has been shown to lead to periprosthetic inflammation, osteolysis, and implant loosening. Cross-linking can reduce the wear of UHMWPE, but it also compromises UHMWPE’s mechanical properties. Accordingly, there are concerns related to potential brittleness if UHMWPE implants are not positioned optimally. Also, the smaller particles generated from cross-linked UHMWPE may present an increased particulate load in vivo. Thus, there is a need for data on the long-term outcomes of cross-linked UHMWPE. Any technology that can reduce bearing wear rates in THA and total knee arthroplasty (TKA) can potentially decrease the morbidity and risks associated with premature revision surgery related to wear. Improved wear resistance also allows the use of large-diameter femoral heads in THA, leading to increased arc of movement and less risk of prosthesis dislocation. The ideal joint bearing for THA and TKA would be able to withstand high cyclic loading for several decades without undergoing corrosion or fretting at modular metal tapers, and would possess proven biocompatibility and material stability in vivo, as well as ultralow wear rates. The search for the ideal total joint bearing has led to the development of ceramic bearings.

Performance-Based Fibre Design for Ultra-High Performance Concrete (UHPC)

The paper presents a method to establish a performance-based fibre design of high-strength micro steel fibres for ultra-high-performance concrete (UHPC). The performance-based fibre design considers effects of fibre layout, fibre orientation, and type of loading (quasi-static and cyclic) and expands the current approach using experiences and suitability testing results. The performance-based fibre design is based on a so-called utilization rate, which is determined via pullout tests of high-strength micro steel fibres in UHPC under quasi-static as well as high cyclic loading with varying orientations and embedment depths. The utilization rate for a straight fibre pullout is 0.27 on average considering the measured tensile strength of the fibre and 0.50 considering the manufacturers specifications. For inclined fibres, additional bending stresses occur at the exit point of the fibre channels, leading to a significant increase in local tensile stress. Therefore, the utilization rate of inclined fibres under quasi-static loading is approximately 60–70% higher than in the case of straight embedded fibres (comparing it to the measured tensile strength). Comparing the utilization rate to the manufacturer’s specification, it increases to approximately 1.00. Under cyclic loading, the additional bending stresses in inclined fibres result in a local increase of the load amplitude, leading to a reduced fatigue resistance and premature fibre rupture, underlining the feasibility of a performance-based fibre design.

Influence of Physical Vapor Deposition on High-Cycle Fatigue Performance of Additively Manufactured Ti-6Al-7Nb Alloy

Load-bearing permanent implants, such as hip or knee joint replacements, are permanently loaded in the human body and must withstand considerable high loading cycles. The characteristic properties of additively manufactured Ti-6Al-7Nb, manufactured by laser powder bed fusion (LPBF), such as a rough surface and high residual stresses, have a detrimental effect on the fatigue behavior of such components. Functional physical vapor deposition (PVD) coatings and heat treatments offer the possibility to influence these properties. For this reason, the effects of stress-relief heat treatment (SR; 600 °C/4 h) and three PVD coatings (titanium nitride (TiN), titanium carbonitride (TiCN), and silver-containing amorphous carbon (a-C:Ag)) on the mechanical properties, in terms of high-cycle fatigue, are identified. Wöhler curves are determined and the staircase procedure ascertains the fatigue strengths. The fatigue strengths increase compared to the as-built condition by 105.4% (SR), 44.2% (TiN), 31.1% (TiCN), and 2.6% (a-C:Ag). Fracture surfaces are analyzed by scanning electron microscopy and show LPBF characteristic defects such as pores. The surfaces are partially divided into forced and fatigue fracture, the latter characterized by fatigue striations. Overall, PVD coatings, and especially SR, lead to an improved high-cycle fatigue behavior.

Thickness and internal adjustment of monolithic resin composite milled crowns: Effect on the load-bearing capacity under fatigue

ObjectivesTo evaluate the fatigue failure load (FFL), cycles for fatigue failure (CFF) and survival rates of different occlusal thicknesses of resin composite simplified crowns with internal adjustments (IA) or without as control (C). Methods30 monolithic simplified crowns of CAD/CAM resin composite (Tetric CAD, Ivoclar) were milled in three different occlusal thicknesses (0.5 mm, 1.0 mm, and 1.5 mm). Half of the crowns were submitted to restricted adjustment with diamond burs on the crown's inner surface and half remained milled without internal adjustment. The samples were treated and adhesively luted onto a prosthetic preparation made of epoxy resin reinforced by glass-fiber substrate. The sets were subjected to a fatigue test (cyclic fatigue: initial load of 200 N; step-size of 50 N; 10,000 cycles/step; 20 Hz; maximum load: 2800 N).Microscopic analysis of tested representative samples was performed. The fatigue data were statistically analyzed (α= 0.05) and the micrograpic images were qualitatively evaluated. ResultsAll specimens from groups 1.0C and 1.5C survived the cyclic loads, while all 0.5C samples failed during the test. The 1.0IA and 1.5IA crowns showed no statistical difference for FFL (2530 N= 2670 N) and CFF (471,000 cycles= 499,000 cycles) between them, and they were both statistically superior to the 0.5IA (FFL= 1812.50 N; CFF= 327,500 cycles). The 1.0 mm and 1.5 mm crowns presented superior fatigue behavior (2530 N–2800 N) compared to the 0.5 mm crowns (1812 N–2140 N), whether internal adjustment was performed or not. A statistically significant difference was found for FFL and CFF of 0.5 mm crowns with and without internal adjustment, with a deleterious impact of the adjustment for both parameters (FFL and CFF: 0.5C > 0.5IA). SignificanceResin composite milled crowns can bear high cyclic fatigue loads despite thickness, although thicker crowns had better mechanical behavior; however, the internal adjustment in the composite resin crown leads to a detrimental effect on its fatigue behavior, which presents a risk of mechanical failure due to premature fatigue.

Cumulative deformations and particle breakage in calcareous sand subjected to drained high-cyclic loading: Experimental investigation

Transportation infrastructures filled with calcareous sand are subjected to a high-cyclic loading. Existing studies indicated that a key challenge in predicting the cumulative deformation of calcareous sand was a lack of thorough knowledge about the effects of various important field factors. This paper presents an experimental study on the drained monotonic and high-cyclic triaxial behavior of calcareous sand. The dependencies of cumulative deformation and particle breakage behavior on practical variables, such as mean effective stress (p'), cyclic stress ratio (ζ), void ratio (e), and stress-induced anisotropy, etc., were summarized for calcareous sand. It was found that a larger e and consolidation anisotropy led to a significant increase in the accumulated axial strain, transforming the stable shakedown behavior to transitional or unstable shakedown behaviors. The increase in anisotropy can cause a remarkable increase in dilatancy, as well as a severe failure. A phase transition state line (PTSL) was observed to exist in e-(p/pa)0.7 plane under high-cyclic loading, where the PTSL was found dependent on initial void ratios. As the p', ζ, e, and anisotropy increase, a larger particle breakage index (Br) of calcareous sand was observed, where the total input energy (Win) played a substantial role. The relationship between Br and Win was found to be unique under high-cyclic loading, regardless of the stress conditions and initial void ratios. Moreover, the relationship between Br and Win under high-cyclic loading was discovered to differ dramatically from that under monotonic loading. An appropriate equation was thus developed to describe the correlation between Br and Win for high-cyclic loading.

Fatigue Analysis of Long-Span Steel Truss Arched Bridge Part I: Experimental and Numerical Study of Orthotropic Steel Deck

The orthotropic steel deck is sensitive to fatigue, and a number of cracks have been found in existing bridges. Based on the long-span Guangzhou Mingzhu Bay steel arched bridge, this paper focus on the cracking process, fatigue mechanism, and fatigue performance evaluation of an orthotropic steel bridge deck under traffic load. A finite element model of a three-U-rib and three-span bridge deck was first established to investigate the stress state and the most unfavorable wheel loading position under the longitudinal wheel load. Then, four full-scale single-U-rib specimens were fabricated with high-strength lower alloy structural steel Q370qD in compliance with construction standards. High-cycle loading was subsequently implemented according to the Specification for Design of Highway steel bridge (JTG D64-2015), and the crack initiation, propagation process, and fatigue failure modes were studied. The results showed the stress at structural concern points is larger than in other locations, which was located around 35 mm from the welding seam of the U-rib and the lower end of the diaphragm plate. The Mingzhu Bay steel bridge deck meets the fatigue design requirements. However, the bottom of the welding seam between the U-rib and diaphragm plate is a dangerous fatigue position, and attention should be paid to the welding quality at this position during construction.

Observing the simulation behaviour of Magnesium alloy metal sandwich panel under cyclic loadings

This study aims to investigate the delamination effect of a metal sandwich panel using a four-point bending simulation under continual spectrum loading. The most recent core designs of the sandwich panel have a cavity that can increase vulnerability in terms of bonding strength under constant cyclic loading. The sandwich panel is simulated under constant cyclic loading using different core design configurations, which are rounded dimple, hemispherical dimple, and smooth surface core design. There are two types of conditions used; no pre-stress and pre-stress loads with variable stress ratios based on Gerber stress life theory. Results showed that dimple core design enhanced mechanical behaviour and fatigue life performance about 33% and 5%, respectively, compared to the sandwich panel with a smooth surface core design. It is highlighted that modification on the surface of core design could be beneficial to enhance the bonding strength performance of sandwich panels and prevent early delamination under extreme conditions such as constant cyclic loading. This study is beneficial to enhance the bonding strength for sandwich panels against extreme conditions such as high impact load and continuous cyclic load.

Cyclic and tensile deformations of Gold–Silver core shell systems using newly parameterized MEAM potential

Gold–Silver (Au–Ag) core-shell nanostructures have significant applicability in stretchable and biocompatible electronics where endurance under high tensile and cyclic loading is a requirement. This work, for the first time, quantitatively investigates the role of dislocations and defect interaction governing the mechanical behavior of Au–Ag and Ag–Au Core-shell nanostructures under tensile and cyclic loading using molecular dynamics (MD) simulation. For accurate representation of the underlying physics, a novel modified embedded atomic model (MEAM) interatomic potential for pristine Au, Ag and their alloys is parameterized through two different density functional theory (DFT) schemes. Using the new potential for MD simulations, the cyclic loading properties of pristine and core-shell nanowires (NWs) in a strain range of −15%–15% for 10 cycles are conducted. The tensile behavior of pristine and core-shell NWs is also explored for temperatures between 300 K and 600 K. A comparative analysis between Core-shell structures and their pristine counterparts are carried out. Our results suggest that Ag–Au Core-shell NW exhibit superior stress-strain reversibility under cyclic loading among the structures examined. Ag–Au exhibit the highest dislocation formation and near-complete annihilation of defects consistently. Au–Ag also present improved cyclic loading properties than its pristine counterparts. For tensile loading, all four structures exhibited deterioration in strength with increasing temperature. Thermal softening is observed to be more prominent in Au–Ag core-shell NWs compared to Ag–Au. Our work lays out a foundation for exploration of mechanical properties of Au–Ag systems using the MEAM potential which will help design components for stretchable electronics and creates a pathway for further exploration of similar binary alloy systems.

Fatigue performance of stainless tool steel CX processed by laser powder bed fusion

This study investigates the fatigue performance of additively manufactured steel CX under uniaxial high cycle loading. The results show that surface quality was the most influential parameter that changed the fatigue behavior of the material, compared to combinations of building orientation and heat treatment as other fabrication parameters. Consequently, improving the surface quality from Ra = 3 μm–1 μm increased the fatigue limit from 170 MPa to 250 MPa. However, heat treatment did not significantly influence the fatigue performance of the material, although it increased the hardness of the material from 320 HV to 460 HV.

Physiological Responses to Acute Cycling With Blood Flow Restriction.

Aerobic exercise with blood flow restriction (BFR) can improve muscular function and aerobic capacity. However, the extent to which cuff pressure influences acute physiological responses to aerobic exercise with BFR is not well documented. We compared blood flow, tissue oxygenation, and neuromuscular responses to acute cycling with and without BFR. Ten participants completed four intermittent cycling (6 × 2 min) conditions: low-load cycling (LL), low-load cycling with BFR at 60% of limb occlusion pressure (BFR60), low-load cycling with BFR at 80% of limb occlusion pressure (BFR80), and high-load cycling (HL). Tissue oxygenation, cardiorespiratory, metabolic, and perceptual responses were assessed during cycling and blood flow was measured during recovery periods. Pre- to post-exercise changes in knee extensor function were also assessed. BFR60 and BFR80 reduced blood flow (~33 and ~ 50%, respectively) and tissue saturation index (~5 and ~15%, respectively) when compared to LL (all p < 0.05). BFR60 resulted in lower VO2, heart rate, ventilation, and perceived exertion compared to HL (all p < 0.05), whereas BFR80 resulted in similar heart rates and exertion to HL (both p > 0.05). BFR60 and BFR80 elicited greater pain compared to LL and HL (all p < 0.05). After exercise, knee extensor torque decreased by ~18 and 40% for BFR60 and BFR80, respectively (both p < 0.05), and was compromised mostly through peripheral mechanisms. Cycling with BFR increased metabolic stress, decreased blood flow, and impaired neuromuscular function. However, only BFR60 did so without causing very severe pain (>8 on pain intensity scale). Cycling with BFR at moderate pressure may serve as a potential alternative to traditional high-intensity aerobic exercise.