Bending Fatigue Performance Research Articles

Influence of Surface Wear Defect on Low-Cycle Bending Fatigue Performance of Single-Strand Steel Wire Ropes

Influence of Surface Wear Defect on Low-Cycle Bending Fatigue Performance of Single-Strand Steel Wire Ropes

The investigation on the bending fatigue properties of Ti-6Al-4V lattice sandwich structures fabricated EB-PBF

In this study, lattice sandwich structures of Ti-6Al-4V alloy with simple cubic (SC) and rhombic dodecahedron (RD) unit cells were prepared by electron beam powder bed fusion (EB-PBF) technique. Through a combination of finite element simulation and experimental investigation, the effect of lattice cell shape and heat treatment on the bending fatigue performance of these lattice sandwich structures was studied. The results show that the underlying fatigue mechanism of the RD lattice sandwich structure is primarily dominated by cyclic ratcheting of the lattice. In contrast, for the SC lattice sandwich structure, the fatigue mechanism involves an interaction of cyclic ratcheting and fatigue crack initiation and propagation of the lattice. During the cyclic deformation process, the struts of the lattice unit cells in the SC lattice sandwich structure mainly undergo buckling deformation. Under the same bending deformation strain, the struts experience much higher stress in the SC lattice sandwich structure, making them more susceptible to crack initiation and resulting in a quick fatigue failure. Therefore, the fatigue performance of the RD lattice sandwich structure is significantly superior to that of the SC lattice sandwich structure. Heat treatment result in the enhanced plasticity of parent materials of the lattice sandwich structure, leading to improved resistance to cyclic strain accumulation during fatigue processes and an increase in fatigue strength.

Experimental study on bending fatigue performance of ambient-cured ultra-high-performance concrete thin plate with embedded steel wire mesh

Ambient-cured ultra-high-performance concrete (ACUHPC) with embedded steel wire mesh (SWM) was studied experimentally. ACUHPC-SWM thin plates having different SWM wire ratios and fatigue load stress levels were tested to clarify the effects of SWM on static and fatigue bending behavior. Subsequently, the fatigue equations for ACUHPC-SWM materials (with different failure probabilities) and reinforcement efficiency of the SWM were proposed. Finally, the reinforcement mechanism of the SWM was revealed by comparing it with ACUHPC thin plates. The results show that the inclusion of wire mesh significantly improved the cracking strength, ultimate static strength, energy dissipation performance, and fatigue ultimate strength of ACUHPC, with maximum increases of 23.63 %, 260.32 %, 940.42 %, and 196.34 %, respectively. As the wire mesh ratio increased, the improvement in fatigue ultimate strength initially increased and then decreased once the wire mesh ratio exceeded 1.884 %. The mechanism according to which SWM enhances ACUHPC involves the action of the mesh as a bridge to delay crack development and increase toughness.

Bending fatigue performance of three‐dimensional woven composites—A review

AbstractThree‐dimensional woven composites (3DWCs) are gradually used in marine, transportation, military, and other applications owing to their high interlayer properties, load‐bearing capacity, and good near‐net‐shape forming abilities. 3DWCs are often subjected to bending fatigue loads, which negatively affect the lives of structural parts. In this review, typical types of preform structures and their evolution characteristics are described, and the micro‐modeling methods for 3DWCs are discussed. The effect of the warp yarn paths on the bending properties and the preform structure on the bending fatigue properties of 3DWCs are summarized, and the application and current status of microstructural models in the study of bending fatigue properties are summarized. In addition, the bending fatigue mechanical properties, damage evolution process, and modes of failure in 3DWCs are discussed. The study status and development of the fatigue life models of the laminated composites and 3DWCs are summarized, and future research work is prospected. This review may be beneficial to preform structural design and contribute to the study bending fatigue properties of 3DWCs.Highlights The microstructural modeling methods for 3DWCs. Types and variation patterns of 3D woven preform structures are described. Effects of the structure on the bending performance are discussed. Bending fatigue properties of 3DWCs are summarized. The development trends of predicting the lifespans of composites.

Study on bending fatigue performance of recycled aggregate backfill subgrade

Recycled aggregate (RA), as a backfill subgrade material, has strong reproducibility and environmental protection, which cannot only effectively reduce resource consumption and environmental pollution but also achieve recycling of resources. Therefore, a study on the bending fatigue performance of RA backfill subgrade is proposed. Based on linear elastic state, softening state, and damage accumulation state, the variation law of bending fatigue damage variables is analyzed, and the stiffness of RA under cyclic load is calculated. According to the correlation between fatigue damage corresponding to two different load links and the constitutive relationship of RA, the identification results of bending fatigue damage state based on RA backfilling subgrade is obtained. The advantages of the fatigue damage model of RA are analyzed, and the fatigue life equation is established based on the damage evolution equation. Strain, stiffness modulus, asphalt saturation, and asphalt mixture adjustment coefficient are selected as model parameters to establish the fatigue damage model of RA. The flexural bearing capacity of the double-reinforced rectangular section is calculated, and the flexural fatigue performance of RA backfill subgrade is analyzed. The test results show that the high stress level in this method leads to a sharp decline in the fatigue life of the specimen, and the influence of fatigue damage gradually appears, which is helpful to improve the durability and safety of the subgrade structure. The range of change shows a small range, which is close to the reduction coefficient result, indicating that this method has high reliability in analyzing the bending fatigue performance of RA backfill subgrade.

Gradient residual stress evolution and its influence on fatigue life under combined carburising heat treatment and ultrasonic surface rolling process

This study combined carburising heat treatment (CHT) with the ultrasonic surface rolling process (USRP) to improve the rotary bending fatigue properties of 18CrNiMo7-6 alloy steel. Based on the experimentally obtained fatigue limit (σ-1), the evolution of gradient compressive residual stress (CRS) of CHT- and CHT + USRP-treated specimens was analysed below the fatigue limit stress level. Subsequently, the evolution mechanism of gradient CRS of the two reinforced specimens was discussed and analysed from the opposing effects of austenite transformation and dislocation density change on the evolution of CRS. The results demonstrated that the selective bending fatigue performance of the alloy was evidently improved after the introduction of CRS; however, the change in fatigue limit was not evident. The durability under other loads (such as cyclic tension/compression and torsion loads) needs further study. The gradient CRS evolution of CHT specimens was mainly caused by the large residual austenite transformation and small dislocation density change. Therefore, the volume expansion caused by residual austenite transformation gradually increased the gradient compression residual stress of CHT specimens with an increased number of cycles. Contrarily, the degree residual stress evolution of CHT + USRP specimens was more affected by the dislocation density, and the gradient compression residual stress gradually decreased with an increased number of cycles. Finally, the residual stress evolution rate of the two reinforced specimens was divided into two stages: fast and slow.

Build Orientation Effect on Bending Fatigue Performance and Impact Toughness of Laser Powder Bed Fusion Manufactured Ti6Al4V Without Heat Treatment

Titanium alloys are highly valued in various industries due to their exceptional qualities. This study examines how the build orientation affects the mechanical and fatigue properties of Laser Powder Bed Fusion (PBF-LB) produced Ti6Al4V, without heat treatment. The research shows mechanical properties vary based on build orientation with vertically oriented specimens exhibiting the highest yield and tensile strengths, while vertical orientation excels in ductility, measured through elongation at break. Impact toughness sees variations with horizontal orientation performing the best. However, build orientation has minimal influence on flexural bending fatigue performance. Both diagonal and vertical orientations show similar fatigue limits at around 40 MPa. Dry electropolishing proves to be an effective technique, significantly enhancing fatigue performance with limits stabilizing at about 150 MPa. This study underscores the importance of considering build orientation in PBF-LB manufacturing for specific mechanical and impact properties and the potential of dry electropolishing in improving the fatigue performance of Ti6Al4V components. These findings offer valuable insights for the additive manufacturing industry, aiding in the optimization of Ti6Al4V component production.

Study on rotary bending fatigue performance of TC4 lattice structure fabricated by selective laser melting

Prediction of the fatigue performance of lattice structures in additive manufacturing still lacks widely applicable methods. To address this issue, we investigated the effect of a BCC lattice structure combined with thin walls and ribs on the fatigue performance of TC4 alloy samples. The lattice-structured samples were fabricated by selective laser melting. In addition, we proposed a prediction model of fatigue performance that combined ABAQUS finite element analysis with FE-safe fatigue analysis. The simulation and experimental results verified the reliability of the model. Based on this method, the effects of lattice and ribbed plate structures on the bending fatigue performance were investigated. The experimental results showed that the stress concentration generated by lattice structures weakened the fatigue performance. On the contrary, ribbed plates can enhance fatigue performance, which also depends on the orientation of the rib structure. The simulation results showed that increasing the volume fraction of unit cells can mitigate the stress concentration, leading to improved fatigue performance. The lattice structure combined with the rib structure exhibited superior fatigue performance. In addition, the proposed models can also be applied to other metallic materials. The findings in this study can provide a theoretical basis for the design of lattice structures with better fatigue performance.

An investigation on bending fatigue in a corrosive environment of dual-phase 1000 sheet steel RSW joints and damage model via experiment and numeric analysis

Fatigue, corrosion, and fatigue damage models are best addressed to improve and understand the service performance of materials, particularly automotive steel. This study is an attempt to experimentally and finite element investigates plain bending fatigue performance and damage model of DP 1000 sheet steel resistance spot welding (RSW) joints in 3% NaCl aqueous corrosive treatment. RSW applications were carried out using different weld currents. The joint samples were then subjected to optical image analysis, tensile shear, and fatigue tests (3% NaCl-aqueous and normal atmosphere). A proper damage model of RSW junctions was developed and corrected by numeric analysis. Besides, RSW nugget formation, tensile shear, and plain bending fatigue tests were also applied. Consequence, fatigue behavior, tensile load carrying capacity, and effective fracture behavior of resistance spot welded joint specimens were evaluated. Results showed that a corrosive environment negatively affected fatigue performance. With the developed model, it was observed that the fatigue life of the samples decreased by 30–35% in the fatigue tests performed in the corrosive environment. Experimental and numerical analysis results of plain bending were compatible.

Fretting fatigue behavior of helical-torsional contact steel wire in wire rope

Fretting wear and torsional deformation of steel wire can reduce the performance of wire rope and threaten the safety of mine hoisting system. In this study, to explore the influence of different torsional deformation on the fretting fatigue wear behavior under multi-wire spiral contact, an experimental study was conducted on a self-made test apparatus. The results show that the increase of torsional deformation can reduce the breaking force of steel wire by about 2.6%, and reduce the bending fatigue performance by about 36.4%. In addition, the maximum wear depth, wear amount and coefficient of wear increase with the increase of torsional deformation. The torsion and deformation of the pearlite lamellae parallel to the tensile stress direction are the main reasons for the decrease of the wear resistance of the main steel wires. More torsional deformation makes the steel wire produce less furrow morphology in fretting fatigue wear. The main wear mechanism of steel wire with small torsional deformation is abrasive and tribochemical reactions, and the main wear mechanism of steel wire with large torsional deformation is surface fatigue and tribochemical reactions.

Study on the Effect of Solid Solution Treatment on the Bending Fatigue Property of Fe-Mn-Si Shape Memory Alloys

Fe-Mn-Si shape memory alloys have excellent low-cycle fatigue performance and broad application prospects in the field of civil engineering and construction. It is necessary to conduct comprehensive and in-depth research on the mechanical properties of Fe-Mn-Si shape memory alloys. This study takes the Fe17Mn5Si10Cr5Ni shape memory alloy as the research object. After solid solution treatment at different temperatures and times, the effect of solid solution treatment on the bending fatigue performance of Fe-Mn-Si shape memory alloys was studied using bending cycle tests. The phase composition and fracture morphology of the sample were analyzed. The results showed that solid solution treatment can significantly improve the bending fatigue performance of Fe-Mn-Si shape memory alloys, reaching the optimal value at 850 °C for 1 h. The number of bending cycles until fracture increased by 131% compared to untreated specimens. Stress induction γ → ε martensitic transformation occurred in Fe-Mn-Si shape memory alloy specimens during bending cyclic testing, which is reversible. The fracture area of Fe-Mn-Si shape memory alloy specimens is mainly characterized by ductile fracture, with some areas exhibiting quasi-quasi-cleavage fracture characteristics.

Influence of Tempering Temperature on Mechanical and Rotational Bending Fatigue Properties of 40CrNi2MoE Steel.

In order to examine the mechanical properties and rotational bending fatigue performance of 40CrNi2MoE steel subsequent to tempering at varying temperatures, the steel specimen was subjected to tempering within the range of 400~460 °C. SEM, EBSD, and TEM were used to analyze the microstructure as well as precipitates. The strain hardening law was studied using the modified Crussard-Jaoult method. Investigations were undertaken to reveal the rotational bending fatigue life with respect to the tempering temperature. The findings indicate that the strength and fatigue life of the examined steels exhibit a decline as the tempering temperature increases, with the primary factor affecting this trend being the alteration in dislocation density. No notable impact on the fatigue fracture morphology exerted by tempering temperature was found within the range of the experiment. The C-J model analysis reveals that the work-hardening behavior of the trial steels is influenced by dislocations and the second phase.

Bending fatigue performance of high-strength seven-wire monostrand

Large-amplitude cable vibrations are remarkably common in cable-stayed bridges subjected to wind and mechanical loading due to low inherent damping of these structures. Although the high slenderness ratio of cables means that bending moments are not normally significant over their free length, local effects near the cable anchorage induce non-negligible bending stress variation under dynamic loading, which could lead to fatigue failure of stay cables. In modern parallel strand stay cables, the fatigue performance depends on the fatigue properties of the individual seven-wire monostrands which together make up the cable. We introduce a new bending fatigue testing device for seven-wire monostrand which can control the fatigue loading in the axial and transverse directions of the cable independently. The fatigue endurance of monostrand with guide deviators is significantly longer than without guide deviators present, especially for smaller bending fatigue amplitudes. We found that bending fatigue life of monostrand is also reduced by increased constant or dynamic axial stress, but over-tensioning of the monostrand (e.g. during construction) had no consistently adverse effect on fatigue life. For monostrand loaded in severe bending, fatigue occurs due to the bending stress variation caused by the combination of bending moments and axial forces at the extreme edges of the monostrand cross-section, rather than due to relative movement and fretting between adjacent wires within the monostrand.

Improved rotating bending fatigue performance of laser directed energy deposited Ti6Al4V alloys by laser shock peening

A major challenge for additive manufactured titanium blades is to improve an unfavorable fatigue life. In this work, the rotating bending fatigue test was carried out on the laser direct energy deposited (L-DED) titanium alloy to simulate the service condition of the rotating blade, and the laser shock peening (LSP) post-processing was adopted to enhance the fatigue performance. The results showed that LSP induced gradient layer and phase transformation in L-DED Ti6Al4V alloy, and increased the fatigue limit to 570 MPa. The compressive residual stress dominated the crack source transfer confirmed by the finite element method, and its retention capacity under fatigue cycles reduced the semi-elliptical crack growth rate. A fatigue limit prediction formula was established to quantify the contribution of microstructure, residual stress and roughness changes.

A Study on the Effect of Gear Hobbing Process Parameters on the Residual Stress of the Tooth Root

The root residual stress during gear machining has a significant impact on the bending fatigue performance of the gear. The process parameters of gear hobbing (hob speed, axial feed speed, and radial cutting depth) directly affect the residual stress of the tooth root. To investigate the relationship between the process parameters of hobbing and the residual stress of the tooth root respectively, an analysis of an orthogonal and single factor was conducted in the hobbing experiment, taking into account the interactions among factors, which revealed the influence rule and primary–secondary relationship of the process parameters on the residual stress of the tooth root. The importance coefficients of the process parameters on the residual stress of the tooth root were calculated using the Least Absolute Shrinkage and Selection Operator (LASSO) method. The results indicate that the residual tensile stress at the tooth root increases with an increase in the hob speed and axial feed speed within the selected range but decreases with an increase in the radial cutting depth. The influence of the process parameters on the residual stress of the tooth root can be ranked as follows: hob speed (importance coefficient 0.460), axial feed speed (importance coefficient 0.278), and radial cutting depth (importance coefficient 0.262). This research provides a basis for improving the residual stress of the tooth root and enhancing the anti-fatigue manufacturing of gears, thus holding significant research value.

Study on biaxial bending fatigue performance of Engineered Cementitious Composites (ECC)

Structural components such as bridge deck, highway pavement and thin-walled roof dome often are subjected to the biaxial and even multi-axis stress state due to the external load. Also, the fatigue effect cannot be ignored due to the moving vehicle load in the design of these structures. If engineering cementitious composites (ECC) is used in the above traditional concrete structures, their performance, such as easy cracking and short service life can be greatly improved. However, the biaxial bending fatigue performance of ECC should be analyzed in detail. At present, the biaxial bending test methods of cement-based materials include biaxial bending test (BFT) and centrally loaded round panel test (RPT). This study used both RPT and BFT test methods to analyze the biaxial fatigue performance of ECC and used four-point bending test (4PBT) uniaxial fatigue test as a reference. The stress levels S were set as 0.5, 0.6 and 0.7. The uniaxial and biaxial bending fatigue failure procedures of ECC were analyzed by plotting the three-stage deflection development curve, the fatigue damage and strain relationship curve based on the linear cumulative fatigue damage theory, and the S–N curve. The fatigue life of ECC biaxial bending specimens was greater than that of uniaxial bending specimens. At S = 0.5, the fatigue life: BFT > RPT. At S = 0.6, the fatigue life of BFT and RPT specimens was close. At S = 0.7, the fatigue life: BFT < RPT. With increasing stress level, the fatigue life of BFT specimen decreases more than that of RPT specimen. The lognormal distribution model and Weibull distribution model were used to fit the uniaxial and biaxial bending fatigue life of ECC, respsectively. Using the double logarithmic fatigue equation, fatigue life under the failure probability PF of 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 was derived. The survival rate represents the level of safety reservation, which could provide reference and basis for the design of ECC bridge deck and highway pavement with different safety reservation requirements.

Bending fatigue performance due to different roughing-finishing sequences and post-processing of components produced by Wire EDM

The relationships between machining conditions, boundary layer and mechanical component functionality are known qualitatively for selected Wire Electrical Discharge Machining (Wire EDM/WEDM) applications and continuous further developments of this manufacturing technology minimize the thermal influences significantly. Nevertheless, the use of WEDM processes has so far been severely limited in safety-critical applications, especially in the field of turbomachinery construction and aerospace. For example, the removal of the generated surface layers is often still mandatory, although cutting processes can also leave a distinct thermo-mechanically influenced rim zone on the component. This conservative approach currently unnecessarily reduces the manufacturing potential of WEDM processes considerably and calls for an objective comparison of component function. In this paper, therefore, the flexural bending fatigue strengths of differently wire-eroded surfaces based on roughing-finishing sequences and optional post-processing treatment are compared with industrially established reference process chains.

Achieving ultrahigh fatigue resistance of Al15(CoCrNi)85 medium-entropy alloy with deformable multicomponent BCC phases

The bending fatigue performance of the Al15(CoCrNi)85 medium-entropy alloy (MEA) with deformable multicomponent duplex BCC phases was investigated. The significantly enhanced fatigue resistance is attributed to the reduced cyclic strain localization, which originates essentially from the duplex BCC phases and the Al addition in the FCC matrix. Al addition in the FCC matrix might enhance the planar slip, which is beneficial for the reduction of the slip irreversibility of dislocations and the cyclic strain localization. The deformable duplex BCC phases with the semi-coherent interfaces efficiently coordinate the incompatible plastic deformation, which would help release the local stress concentration at the phase boundaries. By comparing to the widely used micro-electro-mechanical system (MEMS) material, the Al15(CoCrNi)85 MEA with superior fatigue performance might be accepted as a promising material for micromechanical parts in MEMS.

A comprehensive evaluation of DLC coating on gear bending fatigue, contact fatigue, and scuffing performance

Modern advanced equipment demands higher reliability and longer service life, imposing increasingly stringent requirements on loading capacity of gears. Diamond-like carbon (DLC) coating significantly improves the friction and wear performance, which has potential to be applied to gears to enhance their loading capacity. In this study, a comprehensive evaluation of the DLC coating treatment on the loading capacity of 18CrNiMo7-6 gears was conducted. The surface morphology, hardness gradient, residual stress, and material microstructure of the DLC coated gears have been characterized. Additionally, bending fatigue, contact fatigue, and scuffing tests on the gears were performed, which took more than 1000 h. The results demonstrate that DLC coating significantly enhances surface microhardness, reaching up to 2000 HV, and surface residual compressive stress shows an increase of approximately 200 MPa. The DLC treated gear contact fatigue limits from 1570 MPa to 1770 MPa, and the scuffing limit temperature rises from 224.6 °C to 348.6 °C compared with grinding state. Although DLC coatings do not exhibit an improvement in gear bending fatigue strength, the composite treatment of shot peening combined with DLC coating still enhances its bending fatigue performance.

Bending fatigue performance of L-shaped stapled one-side two-gusset-plate upholstered furniture joints in oriented strandboard

Bending fatigue performance of L-shaped stapled one-side two-gusset-plate upholstered furniture joints in oriented strandboard