Stress Concentration Area Research Articles

A novel asymmetric stress unloading technology in two sides of coal roadway in deep mine: A case study

The existing stress unloading technology using dense equal-diameter large drilling usually results in damaging the load-bearing structure of the shallow surrounding rock of the roadway. Therefore, this study, while providing full anchor cable strong anchorage support for the roadway sides, proposes an asymmetric stress unloading technology on the two sides of a coal roadway. Small-diameter holes are directly drilled in the shallow low-stress area, and the large-diameter stress unloading hole (LSUH) is excavated in the deep stress concentration peak area for the right side of the roadway; utilizing the floor rock roadway, by drilling upward through the rock stratum, excavating the LSUH in the deep stress concentration peak area for the left side of the roadway. Full anchor cable reinforcement technology for the shallow surrounding rock of roadway sides forms a thick layer anchorage load-bearing structure, avoiding cracks further development of the shallow coal seam of the roadway side and creating a quality stress environment for the implementation of the LSUH in the deep area of the roadway side. The small drilling and the coal slag discharge of the roadway left side does not pass through the shallow anchorage area of the roadway left side, and the shallow small drilling on the roadway right side is supported reinforcement by the steel pipe, which minimize the impact of hole-manufacturing on the shallow anchorage area to the greatest extent possible. Large-diameter weak structural stress unloading holes are arranged in the deep stress concentration peak area of far away from anchorage area of the roadway side, making the high concentration stress areas around the roadway be transferred to deeper area without affect the stability of the shallow anchorage area, also making the plastic deformation of the surrounding rock in the stress concentration area of the roadway side be transferred to the weak structural area of the stress unloading holes. A numerical model for the asymmetric stress unloading technology on the two sides of a coal roadway is established to investigate the influence of different stress unloading parameters on the roadway side stress. Engineering practice shows that this technology can ensure the long-term stability of the roadway.

Investigation of Roller Press Surface and Stud Based on FEM Simulation

As an emerging grinding equipment, roller presses are widely used in Cement industry. The current problem with roller press is that the rolls surface is prone to wear and needs to be replaced regularly. This greatly reduces the service life of the roller press and affects the development of the roller press. Therefore, how to reduce the wear on the surface of the roller press and increase the service life of the roller press is an urgent problem that needs to be solved for the current roller press. Current research mainly focuses on the mechanism research of roller press wear and the optimization of rolls surface structure. In this paper, the extrusion force between the stud-lining and the material is calculated by analyzing the stress of the studded rolls under actual working conditions and the compression and rebound characteristics of material layer. The failure modes of studded rolls are mainly divided into two parts. On the one hand, it is fatigue cracking of the roller shaft and stud-lining. On the other hand, it is cracking at the contact between the stud-lining and the stud, and the fracture of the stud. Because the failure modes of the studded rolls are divided into two parts, the studded rolls are divided into two parts for simulation by using ANSYS 18.0 . Firstly, the static analysis is carried out on the roller shaft and the stud-lining, and the distribution cloud diagram of the stress and contact pressure of the roller shaft and the stud-lining is obtained, and the stress concentration area is optimized. After optimization, the contact pressure between the roller shaft and the stud-lining is reduced by about 50%. The maximum equivalent stress of the roller shaft and stud-lining has also been reduced. Secondly, a static analysis was conducted on the stud-lining and studs. Since the stud-lining of the studded rolls are composed of stud holes arranged in a certain order. Therefore, stress concentration is prone to occur around the stud hole. The simulation experiment was carried out by changing the optimization schemes such as the assembly method of the stud and the stud-lining, the distance between the studs, and the length of the stud. To reduce the stress concentration of stud and stud-lining. After optimizing the model of the stud and stud-lining, the maximum equivalent stress of the stud-lining and stud decreased by about 10% and 25% respectively. Through the optimized design of roller shafts, stud-lining and studs. The service life of the studded rolls can be effectively improved and the production cost can be reduced. This can provide a reference for the design of the studded rolls.

Stress analysis and stress fatigue life prediction of RCP impeller based on fluid-thermal-solid coupling

Due to the extreme working conditions of the reactor coolant pump (RCP), it is difficult to repair and replace the structure, so a more accurate technology is needed to analyze the dynamic characteristics of the RCP under extreme working conditions and predict the fatigue life. This paper takes the CAP1400 RCP as the research object, when analyzing the hydraulic excitation characteristics, it is found that resonance may occur when the excitation frequencies are 22fn, 28fn and 33fn, then use the unidirectional fluid-thermal-solid coupling technology to analyze the dynamic stress of the RCP, and then use nCode to calculate the stress fatigue. The results show that the fatigue form of the impeller is mainly stress fatigue, and the maximum equivalent stress value is 100.83 MPa, which appears at the junction of the suction surface of the blade and the front cover plate, and the point with the largest stress fluctuation is at the junction of the suction surface and the hub. The position with the shortest impeller life of the RCP is node 397, in the contact stress concentration area between the suction surface of the impeller blade and the hub, the damage value is 2.833 × 10-12, the cycle life value is 3.53 × 1011 times, and the continuous operation is 364.18 years, which meets the requirements of the RCP. Conforms to the safety criterion of 60 years of safe operation of the RCP.

The Mechanism of Rockbolts in Jointed Rock under Uniaxial Tension

In this research, the rockbolt mechanism of a jointed rock mass under uniaxial tension was systematically revealed with a laboratory test and a numerical simulation. It was found that the rockbolt rock mass experienced five stages under uniaxial tension, the densification stage, elastic stage, plastic deformation stage, progressive debonding stage, and complete debonding stage. The stress-strain curve and ultimate tensile strength of a rockbolt rock mass were analyzed by taking the rockbolt spacing and rockbolt angle as variables. It was found that the improvement effect of the reduction of the rockbolt spacing on the ultimate tensile strength was limited. When the rockbolt spacing was reduced to a certain limit, the stress concentration area between adjacent rockbolts was connected and destroyed, resulting in the increase of the rockbolt rock strength becoming smaller, and even having a downward trend. The increase of the rockbolt angle led to the change of the stress mode and failure mode of the whole structure, and the ultimate tensile strength first increased and then decreased. The optimal rockbolt angle was between 60° and 70°. It is worth noting that there was an obvious mechanical occlusion between the thread on the rockbolt surface and the rock mass, resulting in the multi-stage step-down characteristic of the stress-strain curve in the complete debonding stage. The results of this study can provide a reference for the design and construction of similar projects.

Influence of interaction among multiple cracks on crack propagation in nozzle corner of reactor pressure vessel

This paper analyzes the interaction effects and the propagation (growth) behavior among three semi-elliptic corner cracks. Those interacting cracks are assumed to be in the stress concentration area of the inlet of the AP1000 reactor pressure vessel (RPV). The results suggest that the dominant crack will stop first under the interaction. One of the subsidiary cracks will become a long crack while the other will become a short crack. In the simulations, the interaction factor (γ) of the dominant crack and the stressintensityfactors (SIFs) of the subsidiary cracks are calculated respectively by changing the horizontal and vertical distances. The results show that the value of γ decreases with the increase of the propagation steps. With larger horizontal distances among the cracks, the maximum value of γ will rise. In addition, the maximum value of γ will rise if the subsidiary cracks are moved up vertically. Otherwise, the maximum value of γ will decrease. When the cracks get closer together, the increasing rate of the SIF of the long crack will increase while the increasing rate of the short crack will decrease, whether the subsidiary cracks are moved up or down.

Study on the High Strength Cable Truss System Control of the Surrounding Coal Roadway Excavated in Regions Left Intensively Mining-Induced Stresses

In coal mine roadway support, the arrangement of roadways in areas with high-stress concentrations is a challenging issue. It is crucial to solve this problem in order to ensure the safety and productivity of the mine. In this study, we selected a typical roadway in Zhong Xing Coal Mine, Fen Xi, Shanxi Province, as our research focus. We analyzed the deformation and failure characteristics of the surrounding rock under field mining pressure during roadway excavation through theoretical analysis, numerical simulation, and on-site measurements. Using the Flac3D numerical simulation technique, we studied the stress distribution characteristics of the roadway in the stress concentration area. To address the significant deformation of the roadway, we proposed a high-pretensioned top beam high-strength dual-anchor truss support system (HSCTS) and carefully studied its control mechanism and structural characteristics. After simulating and comparing its support effectiveness with the original support scheme and conducting on-site industrial tests, we determined the HSCTS support system as the alternative support system for roadway 1409. The test results showed that the convergence of the rib plates and the roof was no more than 79 mm and 191 mm, respectively. The significant influence of the roadway on the control of the surrounding rock also indicated effective control of the surrounding rock’s deformation along the 1409 goaf. The support control technology system can provide specific reference values for roadways under similar geological production conditions.

Study on Failure Mechanism and Zoning Control of Weakly Cemented Roadway Adjacent Chambers

The strength of weakly cemented surrounding rock is low, and the bonding ability is weak. The rock forming roadway is affected by the stress disturbance after the excavation and support of adjacent chambers, which can lead to problems such as large deformation of the surrounding rock and significant differences in deformation areas. Through comprehensive theoretical analysis, on-site measurement, and numerical simulation, the distribution and evolution characteristics of stress in the surrounding rock adjacent chambers were studied. The results of this study indicated that, the surrounding rock stress crosses the adjacent chambers and forms a concentrated area near the weakly cemented roadway, and that the stress increase ratio of surrounding rock within the stress concentration range can reach 50%. A longer distance of the chambers from the weakly cemented roadway corresponds to a smaller surrounding rock stress concentration area. When the distance exceeds approximately 12 times the average height of the chambers, the surrounding rock stress concentration tends to disappear. According to the support concept of “allowable deformation” + “released pressure” + “restricted shape”, control countermeasures for surrounding rock at different levels are given, which are dominated by U-shaped steel + flexible material and are effective for controlling roadway deformation.

Simulation-Based Analysis of Micro-Damage to Recycled Concrete-Containing Brick Coarse Aggregates

To achieve sustainable development during urbanization, construction waste is recycled for use as an aggregate in recycled concrete (RC). To determine the influence of the brick content in coarse recycled aggregates on the damage sustained by the resultant RC, the RC was first divided into seven phases: natural crushed stone, old gravel inside waste concrete, bricks, new mortar, old mortar on waste concrete surfaces, and new and old interface transition zones. The Monte Carlo method was then applied to establish a two-dimensional random aggregate model of the RC made with coarse brick aggregates. The ABAQUS software package was used to simulate a uniaxial compression test, the results of which were combined with those of a macro-test to determine the internal damage change rule of brick-containing RC. The stress–strain curves obtained from the simulation coincided well with that of the macroscopic tests. As the brick content increased, the damage zone inside the specimen and the number of microcracks increased. The stress concentration area decreased, as indicated by a lower compressive strength in the macro-test. The results indicate that higher brick contents in RC yield more initial damage inside the concrete and a lower compressive strength.

Analysis of cracking in the rear support shell of titanium alloy

The junctions of the flange girth weld and the struts longitudinal weld in the rear support shell exhibited multiple cracks after long-term test run of an aero-engine. Surface and fracture observations, metallographic examinations, hardness testing, and finite element analysis were utilized to explore the cracking cause of the shell. The results indicated that beach marks and fatigue striations were observed on the fractured surface, indicating a typical fatigue failure. The cracks originated from the inner wall surface at the junction of the girth and longitudinal welds, which were located in the stress concentration area of the shell and underwent stronger stress under thermal loading based on finite element analysis. Additionally, the α-case, which decreased the ductility and fatigue properties of titanium, was generated on the inner wall surface of the girth weld due to poor shielding gas during manual tungsten inert gas welding, which was the direct cause of cracking of the shell.

A method for detecting two‐dimensional plane stress distribution in basin‐type insulator based on critically refracted longitudinal wave

AbstractBasin‐type insulator often has small cracks due to stress concentration. The current method cannot accurately reflect the stress condition of the insulator to find the stress concentration areas. To solve these problems, a method for detecting two‐dimensional plane stress (δ1 and δ2) within different depth ranges in a basin‐type insulator is proposed based on critically refracted longitudinal (LCR) wave. First, the acoustoelastic equation characterising the relationship between the variation of LCR wave propagation time and the plane stress was derived. Next, the propagation characteristics of LCR wave in epoxy resin samples were investigated. Then, the stress distribution within different depth ranges of the insulator subjected to hydraulic load was measured using the proposed method, including direction (θ), δ1 and δ2. The results show that the magnitude of the stress alone cannot accurately characterise the stress state. Points with equal distances to the centre have similar stress magnitudes, but their directions are not the same. With increasing depth, θ remains essentially unchanged at the same location, while δ1 and δ2 decrease, and the rate of decrease varies at different locations. Comparing the measured and simulated data, the results showed that they were in good agreement, and the maximum errors of stress value and θ were 0.69 MPa and 2.97°, respectively, which confirmed the feasibility and accuracy of the stress detection in the proposed method.

Transient electromagnetic detection and numerical simulation analysis of the deformation characteristics of an old goaf in an alpine coal mine area

In this paper, Qinghai alpine mining area is taken as the research object to explore the deformation characteristics of overlying strata in alpine mining area, so as to prevent geological disasters caused by over-exploitation in alpine mining area. The location of old goaf in coal mine is detected by transient electromagnetic method, and the results are used for numerical simulation. The numerical simulation results show that after coal seam mining, the stress gradually increases from the surface to the bottom, and the stress concentration occurs at both ends and the middle of the mining area. The displacement change area is highly coincident with the stress concentration area, and the displacement monitoring map is consistent with the horizontal displacement cloud map analysis, showing a “U” type distribution. The research results have certain reference value for the future study of surface mining subsidence in inclined coal seams.

Acoustic Emission-Based Structural Health Prediction and Monitoring: A Comprehensive Review

In this paper, we report a detailed overview of non-destructive techniques, specifically Acoustic emission, for structural health monitoring in engineering applications. The review comprehensively covers the application of the AE technique for data related to damping and attenuation of structural components made from various material types, including conventional and non-conventional materials. Also, this paper systematically emphasizes research related to data collection processes of variable structural elements, such as stress concentration areas, sensor placement, and methodological monitoring. In addition, the analysis discussed in the review encompasses research that has utilized the AE method to examine the performance of metal and concrete building elements in risky situations, such as high temperatures and creep factors, with and without any visible signs of damage. We also examine various solution techniques, such as empirical wavelet transforms, finite element solutions, and differential quadrature for conventional materials’ damage analysis. Furthermore, the review emphasizes using waveform schemes to assess the vulnerability of damages in unconventional materials, such as laminated composite structures with different geometrical shapes. The paper concludes by presenting an overview of the current state of the AE technique in structural health monitoring and discusses potential future developments. This review is a valuable reference for professionals and researchers engaged in engineering applications related to structural health monitoring.

Review on stress evolution and crack propagation mechanism of double-crack specimens

The distribution pattern of cracks in rock masses, known as the geometric distribution, holds significant significance in understanding the progressive failure mechanism and stress concentration can lead to instability and even failure of the specimens. However, the macroscopic and microscopic mechanisms of crack coalescence and the failure of the sample are not yet clear. Thus, the discrete element method was used to investigate the influence of stress distribution on the fracture coalescence and failure of dual-crack specimens with different arrangements under uni-axial compression in this study. The obtained results were compared and analyzed with laboratory test results. The results show: When the double-crack specimens are under overlapping arrangement, the stress concentration area only appears at the end of the crack, which is conducive to crack propagation, resulting in no coalescence. However, if the two preexisting cracks were arranged in a co-planar or non-overlapping manner, the stress concentration of the sample would not only occur at the end of the cracks, but also between the cracks. As the stress increases, the cracks will gradually expand and connect, forming shear coalescence and mixed mode coalescence (shear and tensile) respectively. In addition, the arrangement of cracks greatly changes the influence of stress concentration on the failure mode of the specimen, leading to the possibility that the coalescence of the specimen may occur in three periods: before, during, and after the peak stress. The findings of this research hold immense importance in comprehending the mechanisms behind the coalescence and failure of rock fractures. Moreover, they provide valuable insights for the analysis and design of rock engineering projects, offering practical guidance for ensuring stability.

Notch Fatigue Life Research Based on Critical Distance Theory

Orthotropic anisotropic steel bridge panels are widely used in civil engineering due to their advantages of light deadweight, high ultimate bearing capacity, and wide range of applications. However, their fatigue problem is serious, and the fatigue-resistant design of the steel box girder diaphragm curved cutout is still difficult. In order to effectively predict the fatigue life of this typical fatigue-susceptible detail, a fatigue test of the specimen with curved notched segments of the diaphragm was carried out. ABAQUS 2016 version finite element analysis software was used to establish three kinds of finite element simplified models of the fatigue specimens with curved notches, and the laws of the influence of different notch radii on the fatigue life of the specimens were studied. Through the finite element solution of the three arc notch specimen models with different radii under the tensile load of 50 kN their respective principal stress distributions were obtained. The critical distance theory was introduced to analyze the characteristic stresses in the stress concentration area of the arc notch, and the point method and line method were used to calculate the characteristic stresses. The fatigue life prediction models of three kinds of notched components were established by combining the material fatigue limit and FE-safe life results. The results show that the point method is more conservative than the line method; no matter if the point method or the line method is used, the characteristic stress and the notch radius are inversely proportional to each other, and it is beneficial for the fatigue life of the structure to appropriately increase the notch radius. The fatigue prediction model of steel box girder diaphragms with curved notches based on the critical distance theory is of high accuracy, which is basically consistent with the test results, verifying the feasibility of the critical distance theory in the fatigue life prediction of notched specimens, and providing a reference for the fatigue life assessment of similar steel structures.

Investigation of Structural Strength and Fatigue Life of Rotor System of a Vertical Axial-Flow Pump under Full Operating Conditions

Axial-flow pumps consider both the conventional pump mode and the pump as turbine (PAT) mode operation and put forward higher requirements for long-term operation stability and structural strength; therefore, it is of great engineering significance to evaluate the structural strength and fatigue life of the rotor under full operating conditions. In this study, based on computational fluid dynamics and the one-way fluid-structure interaction algorithm, the structural strength and fatigue life of the rotor system of a large vertical axial-flow pump under full operating conditions were evaluated and studied. The results show that blade deformation and equivalent stress are generally higher in the PAT mode than in the pump mode. The maximum deformation in both modes occurs at the tip of the blade, while the area of stress concentration is at the root of the blade. Both the deformation and the equivalent stress increase with increasing flow rate. The minimum safety factor occurs at the blade root in both modes, and the safety factor in the PAT mode is relatively smaller than that in pump mode. Therefore, when designing and manufacturing axial flow pumps for turbine duties, priority should be given to material strength at the blade root during PAT mode operation to ensure safe and stable operation. The aim of this study is to provide technical references and theoretical foundations for evaluating the service cycle of axial-flow pumps and the influence on pump life under different operation modes.

Numerical analysis for tunnelling-induced stress and plastic evolution causing instability of multilayered surrounding rock by varying three-dimensional in situ stresses

PurposeThe induction of geological disasters is predominantly influenced by the dynamic evolution of the stress and plastic zones of the multilayer rock formations surrounding deep-rock roadways, and the behaviours and mechanisms of high in situ stress are key scientific issues related to deep-resource exploitation. The stress environment of deep resources is more complex owing to the influence of several geological factors, such as tectonic movements and landforms. Therefore, in practical engineering, the in situ stress field is in a complex anisotropic three-dimensional state, which may change the deformation and failure law of the surrounding rock. The purpose of this study is to investigate the tunnelling-induced stress and plastic evolution causing instability of multilayered surrounding rock by varying three-dimensional in situ stresses.Design/methodology/approachBased on data from the Yangquan Coal Mine, China, a finite difference model was established, and the elastic-plastic constitutive model and element deletion technology designed in the study were analysed. Gradual tunnelling along the roof and floor of the coal seam was used in the model, which predicted the impact tendency, and compared the results with the impact tendency report to verify the validity of the model. The evolutions of the stress field and plastic zone of the coal roadway in different stress fields were studied by modifying the maximum horizontal in situ stress, minimum horizontal in situ stress and lateral pressure coefficient.FindingsThe results shown that the in situ stress influenced the stress distribution and plastic zone of the surrounding rock. With an increase in the minimum horizontal in situ stress, the vertical in situ stress release area of the roof surrounding rock slowly decreased; the area of vertical in situ stress concentration area of the deep surrounding rock on roadway sides decreased, increased and decreased by turn; the area of roof now-shear failure area first increased and then decreased. With an increase in the lateral pressure coefficient, the area of the horizontal in situ stress release area of the surrounding rock increased; the area of vertical in situ stress release area of the roof and floor surrounding rock first decreased and then increased; the area of deep stress concentration area of roadway sides decreased; and the plastic area of the surrounding rock and the area of now-shear failure first decreased and then increased.Originality/valueThe results obtained in this study are based on actual cases and reveal the evolution law of the disturbing stress and plastic zone of multilayer surrounding rock caused by three-dimensional in situ stress during the excavation of deep rock roadways, which can provide a practical reference for the extraction of deep resources.

Analysis of the tribological behavior of the high-speed and heavy-load braking interface with dynamic wear of brake pads

Using a megawatt wind turbine disc brake as a case study, this work analyzes the effects and action mechanism of dynamic wear on the braking interface of the braking pad on tribological behaviors as contact state, temperature field, and pressure distribution. The Archard wear model was incorporated into the solution of the tribological problem of the braking interface in ABAQUS using the arbitrary Lagrangian–Eulerian (ALE) technique through the UMESHMOTION subroutine. The wear interface meshes were changed without modifying other finite element analysis variables. Moreover, wear testing on the inertia braking tester validated the coupled heat-stress-wear model of the brake pad. The differences in the tribological behaviors of the braking interface with and without the dynamic wear of the braking pad were analyzed based on the simulation results of friction and wear in a braking cycle. The study revealed that the tribological behaviors of the braking interface were significantly affected by the dynamic wear of the braking pad. Specifically, the wear evolution changed the contact state, the area of stress concentration, and the temperature field distribution during the braking process. Hence, the wear properties of the brake pad were modified as a result of these tribological behaviors.

Research on Optimization and Numerical Simulation of Layout Scheme of Mining Approach in Downward Slicing and Filling Method

The stability of the filling roof—as an important bearing unit in the stope of the access stope in the filling mining method—is of great significance to guarantee the safe and efficient production of the mine. Arrangement of the mining approach in downward cemented filling stope is the key factor affecting the stability of the filling body roof. Based on a combination of laboratory tests, theoretical analysis, and numerical simulation, the influence of different mining approach arrangements on the stability of the filling body roof is analyzed. The weak filling surface is formed between adjacent mining paths. The mechanical strength of the weak filling surface is significantly reduced by laboratory experiments. The relationship between the distribution of the weak filling surface, azimuth angle, and the stability of the filling roof is further studied by numerical simulation. The results show that, when the upper and lower layered mining approaches are arranged vertically or nearly vertically, the areas of stress concentration and the plastic zone in the numerical simulation results are the smallest, and the stability of the filler roof is the best.

Numerical simulation study on the evolution characteristics of the stress induced by mining in deep adjacent working faces

BackgroundThe mining-induced stress in the surrounding rock after coal seam mining is the primary cause of damage and failure of the surrounding rock in the mining area. However, the magnitude and direction of the stress field induced by mining in the overburden strata during the excavation process of deep and adjacent coal seams are not yet clear, and it is difficult to determine how adjacent working faces interact with each other.ResultsIn this study, a large-scale numerical model was built using FLAC3D (Fast Lagrange Analysis Continua) to simulate the sequential mining process of three adjacent working faces (No.1, No.2, and No.3) in Liuzhuang Coal Mine located in southern China. The results showed that the maximum height of plastic zone development after mining in the No.1 working face was 41 m, and the maximum height of plastic zone development was 33.8 m away from the 13 coal seam. It did not affect the top and bottom of the No.3 working face. The development height of the plastic zone on the roof of the No.2 working face after mining was 52m, and the top and bottom plates of the No.3 working face remained intact. The plastic zone of the floor of the No.3 working face after mining was not communicated with the plastic zone of the roof of the No.1 and No.2 working faces. There was a complete rock layer between the two coal seams, and there was not the mutual influence of the mining activities. During the mining process of working faces No.1 and No.2, the range of dynamic pressure influence was extended up to 100m ahead of the working face. During the mining process of the No.3 working face, the range of dynamic pressure influence was 120 m ahead of the working face. The No.1 working face goaf and the mining of No.2 working face had not disturbance to the No.3 working face.ConclusionsAfter the mining of No.1 and No.2 working faces, the stress in the goaf significantly decreased, and the lateral support stress concentration area of No.1 and No.2 working faces had a relatively small impact on the 13 coal seam. Therefore, the No.1 goaf and mining of No.2 working faces had not disturbance to No.3 working face.

Stress and strain changes of the anterior cruciate ligament at different knee flexion angles: A three-dimensional finite element study

ObjectiveThis study aimed to analyze the stress and strain changes of the anterior cruciate ligament (ACL) at different knee flexion angles using a three-dimensional finite element model. MethodsComputed tomography and magnetic resonance imaging scans were performed on the right knee of 30 healthy adult volunteers. The imaging data were used to construct a three-dimensional finite element model of the knee joint. The magnitude and concentration area of stress and strain of ACL at knee flexion angles 0°, 30°, 60° and 90° were assessed. ResultsThe magnitude of stress remained consistent at 0–30° (P > 0.999) and decreased at 30–90° (P < 0.001, P = 0.005, respectively), while the magnitude of strain increased between 0° and 30° (P = 0.004) and decreased between 30° and 90° (P < 0.001, P = 0.004, respectively). The stress concentration area remained consistent at the proximal end, midsubstance, and distal end between 0° and 60° (P > 0.05). The concentration area of strain increased at the proximal end, decreased at the midsubstance between 0° and 30°, and remained consistent between 30° and 90° (P < 0.001). ConclusionAt the low knee flexion angle, ACL's magnitude of stress and strain reached the peak, and the concentration area of ACL strain gradually shifted from midsubstance to the proximal end.