Bearing Failure Mode Research Articles

Multiscale study on the properties and crack propagation of 2D woven SiCf/SiC with pores using elastoplastic phase field

AbstractTo understand the effect of processing and prefabricated pores on 2D woven SiCf/SiC composites (2DW‐SiCf/SiC), their crack propagation and mechanical response under tension load at meso‐ and macro‐ scale are investigated by a promising elastoplastic phase field method (EPPFM). Of much interest, the computational results are well consistent with the available experimental results, verifying the reliability of EPPFM. A significant dependence on pores is observed in the relationship between the strength, Young's modulus, work of fracture of 2DW‐SiCf/SiC and porosity when pores exist solely in the matrix out of yarns, and both in the matrix and yarns, respectively. Moreover, the more dangerous processing pores at mesoscale near yarn are attributed to the inconsistent deformation of the yarn and matrix. Finally, the EPPFM is used for the effect of geometry size on the joint failure mode of 2DW‐SiCf/SiC plate with prefabricated open holes under pin‐loading. Of importance, the more safe bearing failure mode occurs in 2DW‐SiCf/SiC plate when edge distance‐to‐hole diameter ratio and width‐to‐hole diameter ratio are greater than 1.5 and 3, respectively.

Mechanical‐performance deterioration of RC segment of shield tunnel under high corrosion degree and the transformation of eccentric‐failure mode

AbstractReinforcement corrosion in shield tunnel segments has an important impact on the structure's bearing capacity and failure mode. Generally, a shield tunnel structure is under small eccentric compression, but if the reinforcement corrosion develops sufficiently, then a transition occurs from small to large eccentric load state, thereby lowering the structural bearing capacity and endangering the safety of tunnel operation. In the study reported here, based on the compressive bending load characteristics of the shield lining structure, corrosion test columns with small eccentric loading were designed to simulate the actual force state of the tunnel lining, and the whole evolution process of their mid‐span strain, ultimate bearing capacity, and cracks under different corrosion degrees was analyzed. With increasing corrosion, the bearing capacity, concrete strain, and depth of the compressive zone of a test column decrease more and more rapidly, and at the maximum corrosion degree of 68.32%, the maximum reduction of bearing capacity is 53.23%. The tests show that the failure mode of a test column with high corrosion degree (≥46.25%) is transformed from small to large eccentric failure. Based on theoretical analysis of the normal section bearing capacity of reinforced concrete flexural members, a theoretical method is proposed for calculating the critical corrosion degree for the tunnel lining structure to transform from small to large eccentric failure. The theoretical calculation method is verified against finite‐element calculations, and the present research results offer theoretical support for the durability design and safety evaluation of shield tunnel lining structures.

Experimental study on the seismic performance of two-storey UHPC modular building structure

Ultra-high performance concrete modular building is a new structural system in which the module units made by the factory with UHPC materials are transported to the site for assembly. To study the seismic performance of UHPC module building structures, a two-story full-scale module building structure made by UHPC is designed in this study. Lateral cyclic loading tests are performed to investigate the seismic performance of the module building structures. The bearing capacity, failure mode, stiffness degradation, hysteretic performance, residual deformation, and strain skeleton curve are analyzed. Results indicate that the specimen undergoes three stress stages: elasticity, yield, and ultimate under lateral cyclic loading. At ultimate load capacity, the maximum inter-story drift ratio reached 1/57, and the load-bearing capacity was approximately 1.20 times the yield strength. The average ductility factor of the specimens was 3.42. The cracks mainly appear at the bottom and top of the walls of the module unit, and initial cracks occur at the top of the wall of the upper module unit. The specimen exhibits excellent seismic performance, full hysteretic curves, good dissipation capacity and ductility. The four corners between module units are connected by grouting sleeves in a reliable way to transfer force, which can ensure the overall deformation requirements of the structure.

Multi-scale analysis of ultimate bearing capacity in composite hull joints: failure mechanism and numerical simulation

ABSTRACT Progressive failure analysis method is the main method to analyse the ultimate bearing capacity and failure mode of composite structures. Multi-scale method can effectively reduce the dependence of damage mode and stiffness degradation analysis on material parameters. Based on the multi-scale method, from micro-scale to mesoscale and then to macro-scale, the equivalent modulus and equivalent strength of fibre bundles, single-layer laminates and multi-directional laminates were predicted respectively, and the prediction method of ultimate bearing capacity of large-scale composite structures from material level to structure level was constructed. The mechanical properties of standard composite materials and the ultimate bearing capacity of full-scale composite joints were tested respectively, and the ultimate bearing capacity and failure mode of L-joints were predicted by numerical method. The results show that the numerical simulation method based on multi-scale can accurately predict the ultimate bearing capacity and failure mode of large-scale joints of the hull.

Evaluation and analysis of abrasive wear resistance of hybrid roller bearings under lubricant contamination

Abrasive wear is a common failure mode of rolling bearings. To enhance the resistance of traditional all-steel bearings to abrasive wear, the structure of traditional all-steel cylindrical thrust roller bearings has been appropriately adjusted, and hybrid roller bearings have been formed by replacing some of the steel rollers in the traditional bearings with ceramic rollers. The frictional performance of hybrid roller bearings under lubricant contamination conditions was analyzed, and the wear reduction mechanism was discussed. The results show that under the condition of lubricant contamination, replacing the appropriate amount of ceramic rollers not only helps reduce friction and decrease wear but also contributes to improving the overall temperature rise of the bearing. Furthermore, when the total amount of contaminants is constant, a specific threshold exists for the impact of replacing the number of rolling elements on reducing mass loss. For a substantial reduction in wear with hybrid roller bearings, the replacement rollers should constitute at least one-fifth of the total number of rollers. The wear reduction observed in hybrid roller bearings results from a combination of crushing and refinement, grinding and finishing, and self-healing mechanisms.

Research on cyclic behavior of precast bridge piers with ECC-socket connections

Precast bridge piers with socket connections (SCPs) have been widely studied and certainly applied in recent years. To reduce the punching failure of socket connections, decrease their construction difficulty, and improve their application in complex environment areas, the embedment depth of SCPs needs to be decreased and the cyclic behavior of SCPs needs to be improved. In this study, engineered cementitious composite (ECC) was firstly introduced to the SCPs, a novel precast bridge piers with ECC-socket connections (SCEs) were proposed. Subsequently, 3D finite element models (FEMs) were established and validated against experimental results. Then, a detailed parametric study was conducted to investigate the cyclic behaviors of SCEs, including the embedment depth, ECC height, axial compression ratio, reinforcement ratio, and concrete compressive strength. Finally, a simplified calculation model was proposed to evaluate the bearing capacity and failure mode of SCEs. The results show that the shear damage of the embedded section is more severe for traditional shallow socket connections. Compared to traditional SCPs, the cyclic behavior of SCEs is better and influenced by ECC height and embedment depth, as well as axial compression ratio, reinforcement ratio, and concrete compressive strength. The simplified calculation model is suitable to evaluate the bearing capacity and failure mode of SCEs.

Global buckling of S35657 austenitic stainless steel welded box- and I-section long columns under axial compression

Due to its remarkable combination of high yield strength and cost-effectiveness, S35657 austenitic stainless steel has gained increasing attention in the field of construction engineering. This paper delves into the global stability performance of S35657 stainless steel welded long columns. Leveraging test results from 13 welded long columns, consisting of 4 welded box-section columns and 9 welded I-section columns, a numerical simulation analysis was conducted to scrutinize the bearing capacity and failure modes of each specimen. Utilizing validated numerical models, a parametric analysis was undertaken, exploring factors such as cross-sectional classification, slenderness ratio and initial imperfection. Subsequently, the buckling curves for S35657 austenitic stainless steel welded box-section and I-section long columns, both around the major and minor axes, were evaluated using existing test results and numerical outcomes. Through data fitting and reliability analysis, buckling curves tailored to S35657 austenitic stainless steel welded box-section and I-section long columns for global buckling were proposed for the first time, providing guidance for relevant designs based on the European code (prEN 1993-1-4), the American code (SEI/ASCE 8-22) and the Chinese specification (CECS 410: 2015).

Research on Mechanical Properties of New Aluminum Alloy Scaffold Nodes

This article explores the feasibility of using aluminum profiles to design a new type of foldable scaffolding system. To verify the ultimate bearing capacity and failure mode of structural node connectivity points, mechanical performance tests were conducted on the tensile strength of cast aluminum and angle iron nodes to clarify the ultimate bearing capacity and failure mode of the nodes, providing a reference for using aluminum profiles to make new types of scaffolding.

Axial compressive behavior of reinforced hollow circular high strength concrete filled steel tubular short columns

This study aims to investigate the mechanical behavior of reinforced hollow circular high-strength concrete-filled steel tubular (RHCFST) short columns under axial compression. The axial compression test of 6 RHCFST short columns was carried out, and the bearing capacity, ductility and failure modes of the columns were analyzed. The results revealed that the failure modes of RHCFST short columns primarily included mixed failure, shear failure, and crushing failure. Comparatively, the failure modes of specimens with ordinary reinforcement exhibited a shift towards mixed failure, significant improvement in ductility, and a decrease in the increase trend of ultimate bearing capacity with the growth of steel tube thickness. Based on the test results, finite element models were developed using ABAQUS software for parameter analysis. The results demonstrated a positive correlation between the short column’s bearing capacity and parameters such as steel strength, sandwich concrete strength, steel tube thickness, and ordinary reinforcement diameter. Additionally, the initial stiffness of the short column increased with the increase of steel tube thickness. Considering the mechanical properties and engineering applicability of the member, the recommended design of steel tube yield strength, sandwich concrete strength, steel tube thickness and ordinary reinforcement diameter were given. Furthermore, the axial bearing capacity calculation formulae for RHCFST short columns were proposed. The calculated values were found to closely match both experimental and simulated values, with errors falling within 10 %. Consequently, the formulae can offer a reliable prediction of the member’s axial bearing capacity.

Compressive load capacity of CHS X-joints: The Efficacy of doubler plates

This study explores the effects of doubler plates and alterations in joint configuration, on the static characteristics of X-joints made from circular hollow sections (CHS) with slender walls, concentrating on how they withstand compressive forces applied to the braces. A detailed finite element analysis (FEA) was launched. Its accuracy verified through experimental tests carried out by the research team and by comparing it with existing studies. The investigation included an extensive parametric analysis (by generating 204 models) to evaluate changes in initial stiffness, load capacity, and modes of failure, with a focus on the importance of interactions between the chord and plates and the impact of geometric and material nonlinearities. Findings revealed that the doubler plates significantly improve the maximum load bearing capacity and failure modes under various joint geometrical scenarios. While the benefits of doubler plates in enhancing the durability of X-joints are clear, their effectiveness under axial load was not studied. Based on these insights, the research introduces a new theoretical design equation, based on yield volume theory and nonlinear regression, to accurately forecast the ultimate load capacity of the joints.

Experimental research on pull-out behavior of steel-UHPC composite beams with new composite dowels connectors

In order to study a new type of steel-UHPC composite connector, a total of 16 steel-UHPC composite connectors with steel dowels and studs and steel-UHPC composite connectors with steel dowels without studs were designed and manufactured, and the pull-out test, finite element simulation and theoretical analysis were carried out. The load-slip curve, ultimate pull-out bearing capacity, crack development law of the UHPC layer and crack growth trend of the steel-UHPC interface were experimentally studied. The influence of the type of connector, the height of the steel dowel and the inclination angle of the steel dowel on the ultimate pull-out bearing capacity and failure mode of the specimens were compared by parameter analysis. The test results are compared with the finite element analysis results to verify the accuracy of the finite element model. A simplified calculation formula for the pull-out bearing capacity was proposed. The results showed that the failure modes of 16 specimens were the shear failure and axial tensile failure of the UHPC, both of which were ductile failures. The bearing capacity in the elastic stage and ultimate bearing capacity of the steel dowel connector with headed studs were higher than those of the steel dowel connector. After adding headed studs, the pull-out bearing capacity of the specimens could be increased by about 49% ∼ 84%. When the longitudinal steel bars were added to the bottom of the steel dowel connector with headed studs, the ductility in the loading stage and ultimate bearing capacity of the specimen could be improved. The steel dowel composite connector with headed studs with a steel dowel height of 100 mm and an inclination angle of 65° had better pull-out resistance.

Comparative study between two artificial intelligence techniques (NN and SVM) applied in fault diagnosis of Wind Turbine

This paper addresses the application of artificial intelligence (AI) techniques for the classification of faults in wind turbine. Wind Energy Conversion Systems have become a focal point in the research of renewable energy sources. Reliability of wind turbine is critical to extract this maximum amount of energy from the wind. Many condition monitoring techniques that are based on steady-state analysis are being applied to wind generators. Bearing faults in this generator causes mechanical vibrations and the variations in the air gap density. The air gap flux density is modulated and currents are generated at different frequencies related to the mechanical vibrations. Characteristic bearing frequencies are associated with the physical construction of bearing and its failure mode. Classical spectral analysis using the Fourier transform was used to detect different bearing failure modes. The magnitudes of the frequencies components formed by the bearing defect are small compared to the rest of the current spectrum. This large difference in magnitude makes difficult the detection and classification of bearing faults. In this paper, we show that the utilization of different approaches of artificial intelligence such as neuronal network (NN) and support vector machines (SVM) can be discriminate different failure modes and gives a good basis for an automatic and non-invasive condition monitoring for wind turbine.

Reliability analysis of rolling bearings considering failure mode correlations

AbstractAs an essential mechanical component, a rolling bearing can exhibit multiple failure modes that may occur independently or in correlation with one another. A reliability analysis method that meticulously accounts for the interdependencies among various bearing failure modes is presented in this paper. The examination of wear and fatigue failure mechanisms in rolling bearings is carried out using the Physics of Failure (PoF) approach. By considering the influence of uncertain variables, the limit state functions for individual failure modes are formulated through the application of stress‐strength interference theory. In the context of wear failure, the limit state function is derived using working clearance as the characteristic quantity. On the other hand, the limit state function for fatigue failure is constructed with a focus on fatigue damage accumulation. The Copula function is used to characterize the relationship between wear failure and fatigue failure, and a reliability calculation model for rolling bearings is developed, considering the correlation between these failure modes. Ultimately, the proposed method is utilized to assess the reliability of bearings under two different sets of test conditions. The feasibility of this method is confirmed through test data, demonstrating its effectiveness in predicting bearing reliability. Through the application of this method, engineers can optimize bearing size parameters, select appropriate initial clearances, and enhance the reliability design of bearing.

Study on Bearing Strength and Failure Modes of Single Bolted Joint Carbon/Epoxy Composite Materials.

The growth of the Urban Air Mobility (UAM) industry emphasizes the need for considerable study into assembly procedures and dependability to guarantee its effective integration into air transport networks. In this context, this study seeks to evaluate the mechanical characteristics of bolted joint Carbon Fiber Reinforced Plastic (CFRP), with a particular emphasis on bearing strength. By altering the w/D (specimen width to hole diameter) and e/D (distance between hole center and specimen end to hole diameter) ratios, the study investigates how edge and end distances affect material performance. The study discovered a shift from tension to bearing failure at w/D ratios of 4.0, with maximum bearing strength decreases of 90.50% and 69.96% compared to full bearing failure. Similarly, for e/D ratios of 1.5, 2.0, and 3.0, transitioning from shear to bearing failure at 2.0 resulted in maximum bearing strength losses of 94.90% and 75.96%, respectively. Maintaining a w/D ratio of at least 6.0 and an e/D ratio of at least 3.0 is critical for maintaining maximum performance and stability in CFRP structure design.

Investigation of the geometric parameters on the performance of glass fiber reinforced polymer laminated mechanical joints under fatigue loading

AbstractThe present work optimizes the geometric parameters of glass fiber reinforced polymer (GFRP) laminated pin joints under fatigue loading conditions using response surface methodology (RSM). RSM is utilized to construct polynomial functions that optimally capture the behavior of experimental data, intending to make statistical inferences. Key geometric parameters, that is the edge and width dimensions were studied in pursuit of enhanced performance under fatigue loading of pin joints. The study aimed to validate the effectiveness of the optimized parameters, particularly for attaining load‐bearing capacity, fatigue life, and failure mode using numerical and experimental approaches. Optimal configurations were achieved, that is edge and width equal to 16 mm at which the failure mode shifts to bearing mode. Another configuration with an edge of 20 mm and a width of 22 mm was achieved for optimized fatigue life. These findings underscore the practical implications of the optimization process, with the potential for substantial gains in fatigue life and strength of GFRP laminated pin joints in engineering applications. The identified optimal configurations exhibited a non‐catastrophic bearing failure mode, emphasizing a crucial characteristic that provides prior‐warning before the occurrence of final failure. The experimental results align well with the numerical outcomes regarding fatigue life and the mode of failure.Highlights Parametric optimization of GFRP pin joint under cyclic loading. Optimization of GFRP pin joints via RSM for cyclic loading. Validation through numerical and experimental approaches. Comparison of fatigue life at optimum design points. Depiction of the failure modes using damage pattern under fatigue loading.

Mechanical performance and design of aluminium alloy beam string structures

Aluminium alloys are widely used in spatial structures because of their lightweight, high-strength, and favourable corrosion resistance characteristics. However, the low elastic modulus of this material results in reduced structural stability compared to that of other construction materials. Therefore, this study proposes incorporating prestress into aluminium alloy structures to improve their structural performance. In this study, two types of aluminium alloy beam string structures (ABSS) are presented along with their corresponding joints. Through static tests conducted on various ABSS joint configurations, this study assesses the in-plane bearing capacity and failure modes of the structures, revealing the mechanism by which prestressing enhances the in-plane performance of aluminium alloy beams. Specifically, this study investigates the influence mechanisms of various factors, such as the rise-span ratio, sag-span ratio, and initial cable force, on the in-plane bearing performance of an ABSS through numerical simulations. Finally, a method calculating the ultimate bearing capacity of aluminium alloy beam string structures is derived by employing the Ritz method, accompanied by design recommendations. The results demonstrate that introducing a prestress can significantly increase the load-bearing capacity by 5–6 times, and the flange-connected joint is determined as more suitable for being implemented in ABSS.

Experimental study of bonded, bolted, and hybrid bonded-bolted single lap shear joints with woven CFRP adherends

This paper presents an extensive experimental performance study of bonded joints (BJs), only bolted joints (OBJs) and hybrid bonded-bolted joints (HJs). For each joint type, three test configurations are considered: namely, short, medium and long overlap lengths. In each case, the adherends comprise quasi-isotropic twill woven CFRP. For each joint type/overlap length combination, three specimens are tested for statistical representation. HJs demonstrate 1.4, 1.5 and 1.5 times higher failure load and 1.5, 1.6 and 1.9 times higher stiffness than OBJs, for short, medium and long overlap, respectively. In all test cases, HJs outperform BJs except for short overlaps where BJs outperform both HJs and OBJs. OBJs perform poorly in terms of failure load and Hooke’s stiffness. Nevertheless, due to bearing deformation at bolt hole locations, OBJs experience higher failure displacements than BJs and HJs leading to a desirable energy absorption mechanism compared to HJs and BJs. This is thanks to the bearing failure mode of the joint despite much lower failure load in OBJs. It was found that increasing the overlap length generally benefits BJs. However, for medium length overlap specifically, HJs show better performance than BJs. Stress–strain behaviours show a linear behaviour for all test groups with significant joint rotation for OBJs compared to BJs and HJs. Failure mechanism studies presented in the paper show that BJs fail in cohesive failure mode for all test groups. OBJs fail in bearing mode, which is followed by net tension failure. OBJs experience matrix cracking and delamination at bolt hole locations. On the contrary, HJs experience considerably less bearing failure at bolt holes due to the load bearing contribution from the adhesive.

Comparative study of failure analysis in glass fiber reinforced laminated pin joints under cyclic and static loading conditions

Glass Fiber Reinforce Polymer (GFRP) composite Joints were studied under monotonic loads for aerospace and marine applications, but cyclic loading is also a common and serious concern in these applications. In this current study, GFRP composite pin joints were analyzed under cyclic loading, at various geometric factors experimentally and numerically using finite element analysis (FEA) and also compared with monotonic loading. Fatigue tests were carried out using sinusoidal tension-tension loading and covering a range of stress levels from 50% to 90% of effective failure strength (EFS). Weibull distribution was utilized to predict the reliable fatigue life of joints at various joint configurations. Under cyclic loading rapid degradation of dynamic modulus indicated catastrophic failure with shorter fatigue life, while gradual degradation implied slow micro-crack growth and extended fatigue life with progressive failure while in monotonic loading, a sudden fall in the stress-strain curve represented catastrophic failure, and a zigzag curve indicated bearing failure mode before fracture. The damage rate was also determined from the hysteresis loop cycles which indicate greater loop expansion due to the stiffness degradation and higher energy dissipation shows rapid damage accumulation and shorter fatigue life at higher stress level. On the other hand at lower stress level, moderate enlargement of the hysteresis loop demonstrates extended fatigue life with slower damage propagation.

Mechanical characteristics and stability analysis of an innovative type of steel–concrete composite support in shallow-buried excavation tunnels

Under the influence of the principle of New Austrain Tunnelling Method (NATM), the initial support structure of shallow-buried tunnels in urban soft rock mainly adopts the forms of section steel arches or lattice girder arches combined with bolt-mesh-shotcrete. In order to solve the problems of tunnel deformation and collapse caused by untimely support or insufficient support strength during the construction process, the concept of “timely and high-strength support” was put forward, the high-strength steel pipe grid (HSPG) arch was innovatively designed, and the steel pipe grid bolt-shotcrete (SPGB) structure was established. Next, the flexural bearing performance and failure modes of the joint component and jointless component of the HSPG arch were analyzed, and the design scheme was also optimized by finite element simulation. Then, the full-scale model test of steel pipe grid concrete component (SPGC) under the pure bending load was conducted to explore the coupling bearing effect in a laboratory. In addition, relying on the underground excavation tunnel project of urban subway, the characteristic curves and stability coefficient of surrounding rock and SPGB structure were given by using the principle of convergence-confinement method. Theoretical calculations and on-sit measurements showed that SPGB structure had good adaptability in weak surrounding rock tunnel. In general, the research results were of great significance for clarifying the bearing mechanism and applicable conditions of SPGB structure, and also provided a reference for its further application in the tunnel and underground engineering.

Study of the dynamic response and damage evolution of carbon fiber/ultra-thin stainless-steel strip fiber metal laminates under low-velocity impact

Two configurations of carbon fiber/ultra-thin stainless-steel strip fiber metal laminates (CUSFML) with differing metal volume contents (35.3% and 18.2%) and carbon fiber-reinforced polymer (CFRP) composite laminates were selected for tests. The impact response and the effect of metal volume content on the impact resistance of CUSFML were assessed via experiment and FEM. Inducing damage by drop-weight test within the impact energy range of 18.60–46.23 J, two types of CUSFML and CFRP composite laminates were compared. In particular, the bearing capacity, impact deflection, failure modes, and energy dissipation were considered. The impact modeling using the VUMAT subroutine refines the relationship between energy-dissipating mechanism and damage evolution. The results indicate that CUSFML are characterized by higher impact resistance than CFRP composite laminates under low-velocity impact. The effect of metal volume content on the impact resistance increases gradually with impact energy increasing. Under 46.23 J impact, the CUSFML with higher metal volume content exhibits more concentrated damaged area with severe penetration failure, which is more dominated by metal failure features with a higher proportion of plastic energy dissipation. For CUSFML with lower metal volume content, extensive delamination and damage expansion occurs under the dominance of fiber damage behaviors.