High Fatigue Life Research Articles

Comparative Analysis of Friction and Wear Properties of Titanium Alloy Drill Pipe and Steel Drill Pipe

During the drilling process of complex structural wells such as horizontal wells, the wear, and tear of the drill pipe can lead to its weakened strength, which is one of the important reasons for the damage accidents of the drill pipe. Titanium alloy drill pipes are widely used in major oil fields as a new type of lightweight drill pipe with high fatigue life. To compare the wear performance of titanium alloy drill pipe with wear-resistant zones and traditional S135 steel drill pipe, this article tested and analyzed the chemical composition, hardness, and metallographic structure of these two drill rod materials and established models for these two materials. In the experiment, the wear morphology and wear rate before and after the experiment were analyzed and compared. Finally, based on the experimental results, an in-depth analysis was conducted on the wear mechanism of the drill pipe, and anti-wear measures were proposed. The results show that the hardness of the two materials decreases from the wear-resistant belt to the inner wall, and the microhardness of the S135 drill pipe is about half of that of titanium alloy drill pipe with wear-resistant belt drill pipe; the wear test shows that the wear loss of the S135 drill pipe is 0.1667 g, the wear rate is 0.042 g/h; through measurement, it was found that the wear loss of titanium alloy drill pipe reached 0.0055 g, and the wear rate is 0.0063 g/h. The wear rate of S135 steel drill pipe under the same conditions is 6.7 times that of titanium alloy drill pipe. Through analysis, it is shown that under the same conditions, titanium alloy wear-resistant belts have excellent wear resistance, which can effectively protect the inner matrix and prevent excessive wear of drill pipes. The research results of this article can provide theoretical references for the on-site use of titanium alloy drill pipe and experimental research on drilling tool wear resistance.

Effect of inactive section on cooling performance of compressive elastocaloric refrigeration prototype

Elastocaloric (eC) cooling using shape memory alloy (SMA) with zero direct carbon emission is a promising alternative of traditional vapor-compression technology. Compressive eC refrigeration prototype (ERP) performs high fatigue life but suffers from the limited cooling performance. Many studies focus on enhancing the heat transfer property of compressive eC regenerators to improve the specific cooling power (SCP). However, reducing the SCP loss is also essential for developing high-cooling-performance compressive ERPs but has not been given sufficient attention. In this study, we revealed that the force holder widely used in compressive ERPs works as an inactive section that dramatically reduce the SCP produced by the NiTi SMA active section. Numerical heat transfer simulations and experiments were conducted to study the impact of the inactive section on the SCP at varied operation parameters. Nondimensionalized governing equations of the numerical model revealed that the volume ratio (Volnon) of the fluid channel of the inactive section to that of the active section is the determinant geometric parameter for the SCP decrease. Numerical results show that, larger operation frequency fERP, smaller dimensionless fluid velocity V* and system temperature span (∆Tspan) lead to more pronounced decreases in SCPnon (ratio of the SCP to ideal SCPideal at Volnon = 0) as the Volnon increases. It also indicates that the Volnon should be minimized to better < 0.08 for achieving excellent SCPnon > 0.95. Experiments validate that the regenerator with a reduced Volnon = 0.08 exhibits a notable increase of 30.8% and 66.7% in zero-∆TspanSCP and no-load ∆Tspan respectively, in comparison to the regenerator with Volnon = 0.5. Therefore, minimizing the Volnon of the inactive section via reducing the length and diameter of the fluid channel inside the force holder is necessary and highly recommended for developing high-performance compressive ERPs.

Fatigue life and failure mechanism of nylon 66 cord/rubber composites under wide temperature range

This work simulates the real harsh service conditions of Fiber-reinforced polymer composites (FRPC), and the dynamic adhesion and failure mechanism of nylon 66 (PA66)-reinforced natural rubber (NR) composites under large deformation and wide temperature range are deeply studied by comprehensive analysis of the interfacial adhesion evolution, microstructure and failure damage location of the composites, interfacial heating rate, and modulus ratio of PA66/NR. The failure mechanism of PA66/NR composites is interfacial debonding at −20 °C, 25 °C and 80 °C, whereas that at 120 °C is matrix cracks. Interestingly, at −20 °C, the crack expansion at the interface is slow, and the samples show two-stage damage during fatigue, resulting in the highest fatigue life. At 80 °C, the interface heating rate and modulus ratio of the PA66/NR composites is the lowest, and thus the fatigue life is higher than that at 25 °C and 120 °C. Keywords: fiber reinforced polymer composites, fatigue life, failure mechanism.

An experimental investigation on the influence of environmental ageing on strength and fatigue behavior of different single lap joints

It is essential to examine the performance of CFRP and aluminum specimens after being exposed to environmental aging and to develop a technique that can predict their mechanical function. However, there is limited research on the static and fatigue strength of adhesive, mechanical, and hybrid joints (adhesive/mechanical) after environmental ageing. The study aims to examine the effect of thermal and hygrothermal ageing on the static and fatigue performance of three-point bending joints. Three groups of samples were prepared: I) unaged, II) thermally aged, and III) hygrothermally aged. The bending performance of three different types of joints (bonded, bolted, and bonded/bolted) was evaluated by conducting bending tests using three distinct types of adherends: ATA (Aluminum-to-Aluminum), CTC (Composite-to-Composite), and ATC (Aluminum-to-Composite). Also,the strength of the joints was measured and assessed for both static and fatigue (at three different levels of loading using the new fixture) loading. Static tests showed that bonded/bolted CTC specimens had the highest strength, and hygrothermal and thermal conditions significantly affected the static performance of the three types of joints and substrates. Under fatigue load, the highest fatigue life was observed in bonded, bolted, and bonded/bolted specimens for ATA, ATC, and CTC, respectively. In a bonded/bolted single lap joint, the static and fatigue strength consists of two steps: the initial step corresponds to the strength of a bonded specimen, and the next step starts when the bonded joint fails and fits the strength of a bolted joint. Finally, both ageing and static load percentage reduced the fatigue life and shifted the failure mode of the joints.

Fatigue analysis of wind turbine blade for various materials

A 300 kW horizontal axis wind turbine with S809 airfoil is considered for predicting the fatigue life. The wind turbine blade is designed using Blade Element Momentum (BEM) method. The blade geometries such as chord and pitch angle distributions are determined accordingly the blade is modelled using CREO software. The method of analysis is done by considering both static and transient conditions with varying boundary conditions and different loading pressures. The objective of this work is to identify the fatigue life cycles of the wind turbine blade for various composite materials (Shokrieh and Rafiee, 2016) under various operating conditions. Modelled blade is analysed at both static and transient conditions by considering various composite materials as wind turbine blade material. Simple cyclic loading conditions at stress ratio, R = −1 and R ≠ −1 are considered for the transient analysis. Static analysis is done by taking a single cut-out velocity of 12 m/s. Steady loading and response conditions are assumed; that is, the loads and the structure's response are assumed to vary slowly with respect to time. The fatigue life of the wind turbine is calculated for Glass fibre reinforced plastics-glass fibre, Carbon fibre, Technora fibre, Kevlar fibre and E-glass materials and thereby suggesting the best material having high fatigue life, less damage factor and good safety factor.

Numerical study on the influence of liner geometry and lay-up sequence on the fatigue life of composite hydrogen storage vessel

This study focuses on the effect of liner geometry and lay-up sequence on the fatigue life of composite hydrogen storage vessel (CHSV). The ellipsoidal ratio and the maximum thickness of boundary section are selected as the independent variables for liner geometry and a sequence is determined that can make the vessel have higher fatigue life from 12 different lay-up schemes. The difference of the stress condition of the liner is the decisive factor that leads to the change of the fatigue life of CHSV, and this paper summarizes the influence law of the von Mises stress of liner on the lifetime of the vessel. The results show that stress concentrations in the dome section and excessive amplitude of alternating stress in the cylinder section should be avoided. Finally, a reasonable combination of parameters is determined, which can be a reference for the design of type III CHSV.

Large mechanical damping behaviors in a Heusler-type Co53V30.5Ga12Mn4.5 polycrystalline alloy

Shape memory alloys exhibit strong damping capacity owing to the formation and motion of internal interfaces during the hysteretic superelastic response. Here, we report large mechanical damping behaviors in a Co53V30.5Ga12Mn4.5 polycrystalline alloy. By using Mn substitution for V to strengthen the ferromagnetic coupling in association with the martensitic transformation, the thermal hysteresis in the Co53V30.5Ga12Mn4.5 alloy is enhanced to 31.1 K. Under a low compressive loading of 248 MPa, a large dissipated energy of 2.45 MJ m–3 and a high specific damping capacity (SDC) of 0.39 can be achieved. Moreover, a long-term cyclability of over 10,000 superelastic cycles with the SDC higher than 0.32 is also obtained. Developing high-performance damping materials with the integration of low driving stress, high damping capacity and long fatigue life is of great importance for damping applications.

Effect of manganese phosphate conversion coating with different crystal sizes on fatigue life of 20MnCrS5 steel helical gears

Fatigue pitting is the main failure form of automatic transmission gear at present. In this paper, the contact stress of the tooth surface under different coefficients of friction is calculated by the finite element method. The contact fatigue test and transmission performance were carried out on the 20MnCrS5 helical gears after carburizing with different thicknesses of manganese phosphate conversion coating by a special gear test bench. And the influence of the solid lubricating coating on gear contact fatigue performance was deeply discussed. The results show that the contact fatigue life of the gear treated by manganese phosphate conversion coating is improved by more than 100 %, and the manganese phosphate coated gear with a thickness of 12 µm has a higher fatigue life.

Finite element analysis of a stemmed hip prosthesis to reduce stress shielding in the proximal femur

A finite element analysis (FEA) was performed on four prosthesis designs with different internal structures within identical prosthetic stem geometry. A novel hexagonal structure akin to one of the strongest structures in nature is used internally in the stem. The hip implant designs were then analyzed for an applied force of 3227 N. This force was selected because a typical gait cycle generates forces up to 3.87 times the body weight in the hip joint. The FEA results were compared for various stem designs with rectangular cross-sections. The design objective for a hip stem is to have a low stiffness and stress shielding together with a very high fatigue life. The stress shielding reduction of the prothesis was measured by observing the change in stress distribution in a FE femur model before and after implant. Stress shielding was quantified volumetrically, and the surface stresses of the femur were considered to appraise any increased risk of periprosthetic fracture due to increased bone stress. Subsequently, the stems that had the lowest stress shielding models were then optimized. Results showed a reduction of stiffness of 18%, and a reduction in stress shielding of 30% compared to a solid stem.

Properties and Characterization Techniques of Graphene Modified Asphalt Binders.

Graphene is a carbon-based nanomaterial used in various industries to improve the performance of hundreds of materials. For instance, graphene-like materials have been employed as asphalt binder modifying agents in pavement engineering. In the literature, it has been reported that (in comparison to an unmodified binder) the Graphene Modified Asphalt Binders (GMABs) exhibit an enhanced performance grade, a lower thermal susceptibility, a higher fatigue life, and a decreased accumulation of permanent deformations. Nonetheless, although GMABs stand out significantly from traditional alternatives, there is still no consensus on their behavior regarding chemical, rheological, microstructural, morphological, thermogravimetric, and surface topography properties. Therefore, this research conducted a literature review on the properties and advanced characterization techniques of GMABs. Thus, the laboratory protocols covered by this manuscript are atomic force microscopy, differential scanning calorimetry, dynamic shear rheometer, elemental analysis, Fourier transform infrared spectroscopy, Raman spectroscopy, scanning electron microscopy, thermogravimetric analysis, X-ray diffraction, and X-ray photoelectron spectroscopy. Consequently, the main contribution of this investigation to the state-of-the-art is the identification of the prominent trends and gaps in the current state of knowledge.

Utilization of high contents of recycled tire crumb rubber in developing a modified-asphalt-rubber binder for road applications

Waste tires are generally mixed with asphalt materials to produce asphalt-rubber (AR) or rubberized asphalt through wet-, dry-, and terminal blending processes. However, the limitations such as long-term storage and stability issues of these special products have led to the need for advancing the AR technology capable of mitigating the production-related problems. Thus, the major objective of this research was to re-engineer AR in the form of a set of eighteen modified-asphalt-rubber (MAR) products comprising high contents of recycled tire crumb rubber (CR) through activation and pulverization. A set of MAR products was synthesized through different blending dosages, sequences, and material combinations. The material characterization techniques (attenuated total reflection-infrared spectroscopy and powder X-ray diffraction) revealed that the type of additives and the proportions of each material pose a significant effect on the physiochemical properties of MAR. It is noteworthy that this study emphasized the best use of CR emanating out of scrap tires in paving applications through incorporation of higher volumes (as large as 62%) in the preparation of MAR when compared to the conventional AR binder that currently includes about 15–20% CR by weight of the base asphalt binder. The fatigue performance of MAR-modified dense graded mix (MAR blended with natural aggregates) was compared to the conventional mix, which revealed that the MAR-modified dense graded product will have higher fatigue life by more than two times, and increased durability than the conventional mix. Practically, the MAR products can be used for instant application in pothole patching, rehabilitation, and new construction through dry-process technology by replacing a reasonable proportion of conventional aggregates in the asphalt mix. It is envisioned that the MAR binders will reduce the overall cost of pavement construction by utilizing the untreated (or unprocessed) CR in larger quantities by actively supporting the recycling mechanism and circular economy.

Optimization of Fatigue Performance of FDM ABS and Nylon Printed Parts

This research work aims to proceed with the optimization of Fused Deposition Modeling (FDM) printing parameters for acrylonitrile butadiene styrene (ABS) and polyamide (Nylon) to improve fatigue resistance. For that purpose, the methodology of the paper involves two main approaches: experimental study and finite element analysis. The experimental part of the paper used the Taguchi method to find the effects of printing internal geometry, printing speed, and nozzle diameter on the fatigue life of ABS and Nylon plastic materials. ANCOVA multiple linear regression and sensitivity analysis was used to investigate the effects of printing parameters on the fatigue life of materials. The analysis of the results revealed: Nylon performed better than ABS, but had a higher slope; the 'tri-hexagon' structure resulted in the highest fatigue life, but the effect was statistically significant only for ABS material; the fatigue life of both materials increased with decreasing the nozzle diameter; the printing speed had no statistically significant influence neither on ABS nor Nylon. The experimental results then were validated by numerical simulations and the difference between the values was within ±14% depending on the experiment. Such differences might occur due to numerical and experimental errors.

Fatigue life improvement of similar and dissimilar aluminum friction stir welds by deep rolling

At the moment, high production costs prevent the friction stir welding (FSW) process from further industrial applications even if comparable high fatigue strength of the joints can be reached. Higher welding speed may reduce the production costs but decrease the fatigue strength of the manufactured FSW joints. A potential solution is a mechanical post weld treatment directly after welding to increase the fatigue strength of the FSW joint again. In this study, hydrostatic deep rolling was applied for fatigue strength improvement of similar and dissimilar FSW joints made of EN AW 5083 and EN AW 6082 alloys manufactured with different welding speed. Additionally, the fatigue strength was directly compared to conventional joints manufactured by metal inert gas (MIG) welding and to base material specimen made of EN AW 5083. The surface state in as-welded condition was characterized by surface roughness and residual stress measurements. Fatigue tests were performed to quantify the fatigue strength of the FSW joints. Similar compressive residual stresses were determined after deep rolling for similar and dissimilar joints. No fatigue life improvement was determined for deep-rolled similar joints made of EN AW 5083. However, in this condition, the fatigue life of the specimen was within the range of the base material. Thus, significant lower fatigue life and a high fatigue life improvement by deep rolling were reached for dissimilar joints. An increase of the welding speed from 300 to 800 mm/min strongly decreased the fatigue strength of dissimilar welded joints in the investigated case.

Fatigue life prediction of 3D braided carbon/carbon composites with braided angle variation at elevated temperature

The braiding angle of 3D braided carbon/carbon composites (C/CCs) will change during high temperature fatigue loading, which will affect the fatigue properties of 3D braided C/CCs. In order to realize this dynamic simulation in the high temperature fatigue life prediction of 3D braided C/CCs and further improve the prediction accuracy of high temperature fatigue life of 3D braided C/CCs, a high temperature fatigue life prediction model of 3D braided C/CCs considering the change of braiding angle with fatigue cycle number was established. The establishment of the prediction model mainly includes: a meso-scale representative volume elements (RVEs) of 3D braided C/CCs considering yarn direction and fiber bundle cross-section shape is established at the meso-scale; the high temperature residual stiffness and residual strength models of fiber bundles considering high temperature and stress level are established. Based on the experimental data characteristics of high temperature fatigue residual stiffness of 3D braided C/CCs, a mathematical model of cycle number/braided angles (CN/BAs) is established. The fatigue life prediction model was used to predict the 3D braided C/CCs at 700°C and stress levels of 87% and 85%. The results showed that the prediction error of single flower node was less than 5%. The fatigue life prediction error is less than two times the tolerance.

A new calculation method of bearing reliability of tyre unloader based on heterogeneous dimensional interference model

Bearing is an important rotating support part of tyre unloader, and its fatigue reliability is an important part of the whole system reliability. Because of the huge alternating stress, the support bearing is required to have high fatigue life and reliability. In this paper, combined with stress-strength interference model and statistical theory, the life distribution of bearing steel material is predicted by using group test data; Based on the multi-rigid body dynamics and finite element numerical simulation platform, the reliability of the bearing of tyre unloader under different operating years was predicted by using the different dimensional interference model. The results show that the maximum resultant force of the bearing at the bottom rocker arm of the tyre unloader can reach 150kN, and the maximum transverse and longitudinal forces can reach 108kN and 78kN. When bearing the weight of the whole tyre and turning, the inertia force is the largest, the maximum stress value is 1316.2MPa, which occurs in the bearing inner ring and ball contact part. After the statistics, the stress amplitude distribution of the bearing conforms to Weibull distribution, and the life of the bearing follows lognormal distribution. After 105 tyre unloading, the fatigue reliability of the bearing is lower than 0.82, which is consistent with the actual working condition. Therefore, this model can be used to calculate the fatigue reliability of bearings conveniently and quickly, and provide certain theoretical support for the safety and fatigue reliability prediction of bearings.

Research on root appearance and fatigue life of steel catenary riser (SCR) using GMAW/GTAW-P double-sided root welding process

A steel catenary riser (SCR) is a flexible stand-up pipe that connects a subsea wellhead in the seabed (normally at a depth of more than 1500 m) to a floating platform. Waves, ocean currents, and winds apply substantial loads to SCRs that produce fatigue damage. Hence, the requirements for the appearance of SCR weld joints, particularly the weld root, are extremely strict. This paper proposes a new gas metal arc welding/pulse gas tungsten arc welding (GMAW/GTAW-P) double-sided root welding process for SCRs to obtain a nearly smooth root geometry. Test results show that the average values of root reinforcement, root transition angle, and transition radius achieved with this root welding process are only 169 μm, 6.4°, and 4055 μm, respectively. These values are dramatically lower than those achievable with the best technologies available, such as the surface tension transfer (STT) root welding process and cold metal transfer (CMT) root welding process. The fatigue strength of the double-sided welding joints is improved by at least 45.8% because the root stress concentration is significantly reduced. However, incomplete penetration defects were found when the molten pool position was not appropriate. Solutions for this problem are discussed. The proposed process is believed to be a potential strategy for welding high fatigue life SCRs.

A comparative analysis of engineering and economical suitability of bituminous mastics containing waste fillers

This novel study focused on comparing the effect of waste glass powder (GP), waste-dried Kota stone slurry (KS), glass-hydrated lime composite (GL), and conventional stone dust (SD) fillers on the engineering and economical performance of bituminous mastics. Bituminous concrete mixes incorporating the fillers mentioned above at multiple proportions (4%, 5.5%, 7.0%, and 8.5% by weight) were prepared and characterized. The filler-bitumen ratio corresponding to each bituminous mix was determined and used to design its corresponding bituminous mastic. The rheological characteristics of bituminous mastics were compared by investigating their engineering performance against rutting, fatigue, and long-term ageing, using a series of sophisticated tests, namely multiple stress creep and recovery (MSCR), linear amplitude sweep (LAS), and ageing index (AI) analysis, respectively. It is inferred that an increase in filler volume concentration in the bituminous mastics leads to its enhancement in resistance against rutting and long-term ageing. More specifically, GL mastics outperformed in terms of rutting and ageing resistance, followed by GP, KS, and SD mastics. Considering fatigue resistance, SD mastics indicated higher fatigue life than the mastics prepared with waste fillers. In terms of economic performance, using a higher amount of fillers in mastics tends to reduce the cost-benefit ratio (C/B). In particular, utilizing GL mastic seems to deliver better engineering performance in a more economical manner, followed by GP, KS, and SD. These inferences were further validated using statistical analysis, confirming the significant influence of filler type and filler content over the analyzed engineering parameters.

Extremely high energy density and long fatigue life of nano-silica/polymethylvinylsiloxane dielectric elastomer generator by interfacial design

Dielectric elastomer generator (DEG) can harvest electrical energy from various movement in nature such as human walking and ocean waves. To achieve high energy harvesting performance of DEG, dielectric elastomer (DE) composite with strong interfacial interaction, and thus high electrical breakdown strength (Eb) and long fatigue life (NFL) at high strain is a key. In this study, nano-silica (SiO2)/polymethylvinylsiloxane (PMVS) DE composite with strong interfacial interaction for DEG with extremely high energy density (w), high power conversion efficiency (PCE) and long NFL was prepared by designing and synthesizing a new polar macromolecule coupling agent (MCA), ester group grafted liquid butadiene rubber using a photoinitiated thiol-ene click reaction. Compared with the common small molecule coupling agent (SCA) modified SiO2 (SCA@SiO2)/PMVS composite, the new MCA modified SiO2 (MCA@SiO2)/PMVS composite shows much stronger interfacial interaction owing to the largely increased co-crosslinking junction and chain entanglement, resulting in the significantly improved elongation at break and Eb at high strain (400%). As a result, MCA@SiO2/PMVS DEG exhibits an up-to-date highest w (92.2 mJ/cm3) and PCE (35.8%) among the previously reported DEG using unprestretched DE film, and its NFL reaches 141000 times, 3.9 times that of SCA@SiO2/PMVS DEG (36000 times). Thus, MCA@SiO2/PMVS DEG shows the highest full-life generating energy density (9710 J/cm3), 4.8 times and 2427 times that of SCA@SiO2/PMVS DEG and commercial VHB DEG, respectively.

An experimental study of anisotropic fatigue behavior of rolled ZK60 magnesium alloy

The strong anisotropy of wrought magnesium alloy significantly affects its application in structural components bearing fatigue loads. This study aims to explore the effects of grain orientations (RN-N versus RN-R) and sampling surfaces (RT-R versus RN-R) on the fatigue behavior of the ZK60 Mg alloy. Stress-controlled fatigue tests and quasi-in-situ EBSD tests were carried out on three different specimens. The sampling surface and grain orientation both have significant effects on the fatigue life of samples, especially at low-stress amplitude. Although the sampling methods are different, the three samples show similar cyclic evolution patterns. The consumption of available twins dominates the cyclic hardening behavior in the fatigue early stage. When loaded along ND, abundant intersecting twins induced by various variants can produce large plastic deformation, which is detrimental to the fatigue resistance of RN-N samples. When loaded along RD, the activation of specific twin variants leads to the reduction of the twinning areas, thus decreasing the plastic deformation of RN-R and RT-R samples. In addition, the constraint force along the width direction and sandwich-like metallographic structure of RN-R samples will hinder the activation and growth of twins, which results in smaller twinning areas and higher fatigue life than RT-R samples.

Quasilinear pseudoelasticity and small hysteresis in SLM-fabricated NiTi

NiTi shape memory alloys with quasilinear and slim pseudoelasticity are desirable for high fatigue life and easy controllability. This paper reports that the selective laser melting (SLM) technique can encourage formation of quasilinear pseudoplasticity with small hysteresis of NiTi. The NiTi parts are found to present a high density of dislocations in the as-fabricated state. Deformation cycling of the defect-containing SLM NiTi parts promotes the formation of a unique microstructure consisting of nanocrystalline and amorphous-like phases. Such microstructure leads to a continuous and quasilinear type pseudoelasticity with small hysteresis. It is found that the scanning speed of laser affects the dislocation density and transformation behaviour, thus influencing the pseudoelastic behaviour of the SLM-fabricated NiTi. The transformation temperatures are shown to decrease while the transformation intervals to increase with increasing the scanning speed due to the increased dislocation density. The mechanically cycled SLM fabricated NiTi with a scanning speed of 850 mm/s exhibits a stable quasilinear pseudoelasticity of 5.8% and a small energy dissipation of 1.4 MJ/m3.