Fatigue Failure Resistance Research Articles

Design and construction of a custom implant of the temporomandibular joint produced by additive manufacturing in titanium alloy from computed tomography

Biomodels are physical reproductions of anatomical structures of regions or organs of the human body used for diagnosis and surgical planning. The use of tomographic images for generating 3D models and manufacturing of biomodels has been awakening a great interest in the medical area. It is possible, with the use of medical images, to generate representative computer models, thus enabling several simulations and biomechanical analysis of the region or organ of interest, aiming at the manufacture of customized prosthesis or orthesis. In this work we present the project of a customized implant of the TMJ, mechanically ordered and manufactured in titanium alloy by the additive manufacturing process of DMLS. Through the model created for the TMJ region, computer simulations of stresses and deformations were performed on the mandible virtually implanted in the patient, considering severe stresses of human chewing applied to the frontal teeth. With the data from the computer simulations the prosthesis was analyzed through a conventional analytical design process to verify the fatigue failure resistance. The implant was fabricated in titanium alloy by additive manufacturing and was realized physical simulations of the coupling of the prosthesis in the biomodel of the mandible fabricated by three-dimensional printing.

Residual Stresses and the Microstructure of Modeled Laser-Hardened Railway Axle Seats under Fatigue

Railway wheels are usually attached to axles by press-fitting; therefore, the mechanical processes taking place during operation can result in failure, with fatal consequences for the axle seats. This manuscript describes the effect of laser hardening on the residual stress state, microstructural parameters (lattice defects—dislocations, crystallites, microstrains, etc.), and mechanical properties of laser-hardened EA1N steel railway axles under fatigue life conditions. Differences were found between ground, single-track, and multi-track hardened surfaces. Tensile residual stresses, low dislocation densities and hardnesses, and different microstructures (tempered cubic martensite) were found at the overlapped tracks and at the boundary of the heat-affected zone and bulk surface compared with the hardened zone. As a result, the surface treatment of axle seats by laser hardening improved the fatigue failure resistance compared with untreated seats. Optimal properties of the integrity of the axle seat surface were achieved, including fatigue resistance, which seems to be positively influenced mainly by sufficient hardness and the appropriate microstructure. The influence of the other investigated parameters was not evident, and was reduced by the presence of fretting corrosion and press-fitting.

Effect of Ultraviolet Aging on Rheological Properties and Microstructure of Rubber Asphalt in High Altitude Area

High altitude and strong ultraviolet radiation in Qinghai Tibet Plateau induces the brittleness and hardening of asphalt, which leads to temperature cracks, pits and other diseases of asphalt pavement. In this paper, the accelerated UV aging test of rubber asphalt was carried out by simulating the UV radiation intensity in Xining, Qinghai Province, and the rheological properties and microstructure changes of rubber asphalt were analyzed. The results show that the complex modulus of rubber asphalt increases exponentially with the extension of UV aging time. The phase angle of rubber asphalt decreases linearly with UV aging, and the deformation recovery performance of rubber asphalt increases; UV radiation has the most significant effect on the micro morphology of rubber asphalt. With the further extension of UV aging time, micro cracks are formed in rubber asphalt, and the low-temperature crack resistance and fatigue failure resistance of rubber asphalt are gradually reduced.

On the fatigue strength calculation of the welded shell structures from high-strength steels under low-cycle loading. Part 2: Development of the assessment methodology

The first part of this work substantiates the procedure for estimating the number of cycles before the appearance of a detectable fatigue crack in weld joints (stress concentrators) which are the usual places of crack occurrence in the absence of major technological defects. It is based on a physical model of the initial stage of fatigue failure, generalized data on the fatigue failure resistance of high-strength steels and their welded joints and FEM calculations. It is reduced to interpolation formulas summarizing the results of numerical modeling. This (second) part of the study presents information necessary to perform practical assessment of fatigue strength in the field of low-cycle loading, including the choice of reserve coefficients when calculating the resource of welded structures. The results of the assessments are compared with the data obtained during fatigue tests of welded joints of large thicknesses performed by multi-pass welding.

Atomic mechanisms of separation failure at the asphalt–aggregate interface and its dependence on aging and rejuvenation: Insights from molecular dynamics simulations and DFT calculations

The microscopic interfacial properties between asphalt and aggregates determine the macroscopic cracking behaviors of asphalt mixtures. To provide guidance on durability enhancement for reclaimed asphalt pavement mixtures that are prone to cracking, the fracture resistance of asphalt–aggregate interface and its dependence on aging and rejuvenation was investigated by molecular dynamics simulations and density functional theory. The results revealed that although the separation resistance is influenced by the loading rate, temperature and aggregate composition, the separation of the virgin interface system usually occurs within the asphalt region. The aged interface also tends to separate inside the asphalt, but if the asphalt is severely aged, debonding occurs at the asphalt–aggregate interface because the cohesive strength within asphalt is stronger than the interfacial adhesion strength. The aged interface exhibits higher resistance to complete fracture than virgin interface under non-repetitive loading. However, the enhanced molecular polarity of aged asphalt reduces its molecular flowability, thus weakening the resistance of aged interface to fatigue failure. Rejuvenators containing both polar carboxyl groups and nonpolar alkyl groups function as intermediaries to promote the compatibility of aged asphalt molecules with virgin molecules, thus restoring the flowability and fatigue failure resistance of aged interface systems.

Influence of heat treatment on tribocorrosion properties of Ni-B composite coatings

Various surface protection technologies, in particular, electrochemical, are used to increase the wear and corrosion resistance of steels and alloys. Composite electrochemical coatings (CEC) technology is more promising than "pure" galvanic coatings. Application of CEC increases the wear, corrosion and fatigue failure resistance of metals. Nickel often is chosen as a CEC matrix because it easily forms uniformly filled defect-free composite structures with many particles of the dispersed phase (DP).
 Physical and mechanical properties of metal coatings determine practical application of such composition. The characteristics of nickel-based CEC are: high hardness and strength, significant corrosion resistance in atmospheric environment, as well as in alkali and mild acidy environments. An effective composition coating with tribological designation can be CEC Ni-B, received in the process of electrolysis from suspension of amorphous boron in nickel electrolyte. A new composite structure of matrix filled type Ni-Ni3B is formed after heat treatment. Composition and structure of coating is determined by regimes of diffusion annealing. Ni-B coatings increase wear resistance of steel in chlorine-based environments. The influence of low-temperature thermal treatment of Ni-B CEC on steel 09Mn2Si on their tribocorrosion behavior is investigated. It is shown that the structural factor has a decisive influence on the efficiency of such friction pairs. The CEC has the least wear and the most positive compromise electrode potential after vacuum annealing at 450°C, when the initial stage of solid-phase interaction of coating components with the formation of Ni-Ni3B occurs.

Penalization techniques for fatigue‐based topology optimizations of structures with embedded functionally graded lattice materials

AbstractTopology optimization is widely used in industry to determine optimal load paths while satisfying stringent constraints. Recently, functionally graded lattice materials have been integrated into structural design for weight minimization, performance improvements, among others. One subject of interest is the long‐lasting designs with high fatigue failure resistance. The focus of this article is twofold, namely, to present readers with a step‐by step guide to derive sensitivities for various fatigue performances in gradient based topology optimization and to present and compare new and old methods for cumulative damage objectives. New formulations for cumulative damage assessment that modify local damage in topology optimizations by influencing local stress, yield strength or SN‐curve intercept are presented. Effects of functionally graded materials are also investigated to measure potential improvements in damage resistance. Methods of gradient descent such as moving asymptotes and sequential quadratic programming are included to compare solutions of fatigue minimization problems. The analysis shows that traditional method of stress penalization is the most effective to obtain satisfactory load paths for fatigue minimization when compared to yield and SN‐intercept penalization. Multiple benchmark tests provided results which showed slower convergence when yield strength penalization is activated which also required significantly more computation time than other methods.

Tekerlek Ray Etkileşimi, Perlitik ve Beynitik Çeliklerin Yorulma Hasar Direnci Üzerine Bir Sonlu Elemanlar Analizi

Bu çalışmada ülkemizde ve dünyada demiryolu hatlarında işletme şartlarında çoğunlukla kullanımda olan perlitik mikroyapıdaki çelikler ve perlitik çeliklere alternatif olarak sunulan, gelişmiş mekanik özelliklere sahip olan beynitik mikroyapıdaki çelikler ele alınmıştır. Geniş bir literatür özetiyle konvansiyonel ray sınıfları ve gelişmiş ray sınıfları, kimyasal kompozisyonları ve temel mekanik özellikleri dikkate alınarak değerlendirilmiştir. Ayrıca dünyada farklı bölge ve ülkelerde geliştirilen beynitik ray çelikleri incelenmiştir. Daha sonra tekerlek ray etkileşimi, sürtünme şartları ve temas yüzeyleri dikkate alınarak, geliştirilen sonlu elemanlar modelinde rayın yorulma hasar direnci analiz edilmiştir. Sonuç olarak analiz edilen beynitik mikroyapıdaki çeliğin yorulma hasar direncinin perlitik mikroyapıya göre üstün olduğu ve 386,69 MPa yük altında on milyon çevrime dayanabildiği anlaşılmıştır.

Evaluating the mechanical performance of asphalt mixtures in cyclic torsional shear test

In this paper, the mechanical performance of asphalt mixtures was examined in cyclic torsional shear test, in which the relationship between the averaged shear strain, γav, and the number of cyclic loading, N, was obtained by using a short, about 25mm height, specimen. In these tests, the effects of some influencing factors such as the type of asphalt mixture, the thickness of specimen and the temperature were examined. In each test, four indices; i.e., the slope of plastic flow line, the slope of stripping line, the number of load applications at the inflection point for stripping and the averaged shear strain at the inflection point for stripping, were defined for the relationship between γav and N. As a result of this study, we clarified that various performances such as rutting resistance, fatigue failure resistance and the stripping resistance of asphalt mixture can be appropriately evaluated by using the cyclic torsional shear test.

A review on failure mechanisms and analysis of multidirectional laminates

Advanced composite materials have excellent mechanical and physical properties, which are wide, used in aerospace, automobile, biomedical, recreational (sport), and structural industries. Because composite materials have high stiffness and strength, fatigue failure and corrosion resistance, and low density compared with meals and metals alloy. But, composite materials' properties became poor performance due to manufacturing defects, fiber-matrix stacking sequences, fiber orientations, and other factors. These factors lead to multidirectional (MD) composite laminates failure. This paper presents a review of recent work on failure analysis of multidirectional composite laminate from the last two decades of published researches. This review paper reported MD composite laminates' failure mechanism at various failure criteria, such as maximum strain/stress failure criteria, quadratic failure theory (Tsai-Wu theory), Tsai-Hill criteria, Hashin criteria, Puck failure criteria, and others criteria. Finally, this paper presents a meaningful conclusion.

Fatigue Analysis of Bitumen Modified with Composite of Nano-SiO2 and Styrene Butadiene Styrene Polymer

Since fatigue cracking is caused in the middle-temperature conditions due to the stresses from heavy traffic and as the bitumen plays a very important role in controlling this failure, therefore, in recent years, the production of the modified bitumen that can give a good performance in the middle temperatures has always attracted the interest of researchers. One of these bitumen modifiers is the styrene butadiene styrene (SBS) polymer. Due to the phase separation of bitumen and polymer, aging and oxidation, this polymer may not exhibit expected field performance at middle temperatures. Therefore, in this research, it is attempted to analyze the middle-temperature performance using the combination of nano-SiO2 and SBS polymer in the bitumen modification. In this paper, the addition of SBS and nano-SiO2 to the base bitumen resulted in the reduction of the complex modulus, phase angle, storage modulus and loss modulus at middle temperatures, thereby improving the potential of fatigue failure resistance. In general, considering the requirement for the rotational viscosity value up to 3 Pa.s at 135 °C and also, regarding the economic issues in choosing a lower percentage, the combination of 4.5% SBS + 3% nano-SiO2 is selected as the optimal composite.

Enhanced very high cycle fatigue resistance of solution treated Mg–10Gd–3Y–1Zn–0.5Zr magnesium alloy containing long-period stacking ordered phase

We explored the very high cycle fatigue (VHCF) behavior of solution treated Mg–10Gd–3Y–1Zn–0.5Zr (wt. %, GWZ1031K-T4) alloy containing long-period stacking ordered (LPSO) structures. The fatigue strength of GWZ1031K-T4 alloy at 109 cycles is about 115.0 MPa, and the corresponding fatigue ratio is approximately 0.44. Crack initiation that causes fatal failure was found to occur primarily from the specimen surface in the high cycle fatigue regime and the subsurface in the very high cycle fatigue regime, accompanied by crystallographic facet formation irrespective of a lifetime. Our results reveal that the basal slip activated in the matrix grain substantially alleviated strain localization during VHCF testing. The unique microstructure, featuring block-shaped LPSO structures scattered at the grain boundary, a large amount of thin LPSO phase and stacking faults enriched with solute atoms (SFs) homogenously distributing in the alloy matrix, and supersaturated Gd and Y atoms in the nano-scale Mg layers in the grain, is proposed to account for the enhanced fatigue failure resistance of GWZ1031K-T4 alloy.

Statistical Estimation of Fatigue Resistance for Parts Using the Theory of Fatigue Failure Similarity

The problems on determining the design fatigue resistance characteristics of materials and structural elements by using methods of the statistical theory of fatigue failure similarity are considered. The results of vast number of fatigue tests conducted by various researchers and research and production enterprises for samples of different sizes, models and full-scale parts have been subjected to statistical analysis. In order to justify the similarity criterion for fatigue failure in a wide range of durability and fracture probabilities, we have obtained correcting relations that allow us to estimate the characteristics of fatigue failure resistance on the basis of the median fatigue curve of standard samples and reference parameters of the similarity theory without the need to test full-scale structural elements.

Investigation of Fatigue Failure Performance of Ankle Implant Mobile Bearing using Finite Element Method

The Fatigue of the mobile bearing component of ankle implant became one of the main causes of failure in ankle implant. This paper deal with the investigation of fatigue failure performance of mobile bearing for different gait cycles (normal, dorsiflexion and plantarflexion) using finite element method. The finite element analysis is one of the method to predict fatigue and identify the critical area that have highest contact stress on mobile bearing design of ankle implant. The three-dimensional solid modelling of STAR and BOX ankle implants are constructed using SolidWorks software. The finite element analyses are performed by using ANSYS software. The finite element model of the mobile bearing was analysed using static structural analysis approach. The most critical area on the mobile bearing of ankle implant was found on its middle bottom area. The obtained results also showed that the STAR mobile bearing has the higher life cycle than BOX before fatigue failure occurs. This finding is similar with experimental and clinical result done by previous researcher. Therefore, our Finite Element Model has potential to improve the mobile bearing at the designing stage to be better in future in term of fatigue failure resistance and has longer life span.

Fatigue survival and failure resistance of titanium versus zirconia implant abutments with various connection designs

Statement of problemData regarding the effect of connection design and abutment material on the fatigue survival and failure resistance of implant abutments are scarce. PurposeThe purpose of this in vitro study was to investigate the effect of connection design and abutment material on the fatigue survival and failure resistance of implant abutment assemblies. Material and methodsThree types of implants (n=18, N=54) and 6 groups of abutments (n=9, N=54) with different connection designs—internal conical (IC), internal tri-channel (IT), and external hexagonal (EH)—and abutment materials—titanium (T) and zirconia (Z)—were investigated. All the abutments were restored with identical central incisor crowns. Fatigue testing, including thermal and mechanical aging, was performed in a mastication simulator (Esetron Smart Robotechnologies) for up to 1.2×106 cycles with a load of 50 N at an angle of 45 degrees. Then, the surviving specimens were subjected to failure resistance testing in a universal testing machine (Shimadzu AG-IS; Shimadzu Corp) at a crosshead speed of 1.0 mm/min. The maximum loads to failure (N) were recorded. Survival performance of the specimens throughout the fatigue testing was examined by the Kaplan-Meier survival analysis. The failure loads were analyzed by using the Kruskal-Wallis test followed by the Mann-Whitney U tests with Bonferroni-Holm correction (α=.05). ResultsAll the specimens of groups ICT, ITT, ITZ, and EHT survived fatigue testing, whereas 2 specimens from group ICZ and 3 specimens from EHZ failed. Statistically significant differences were found among the groups, based on the results of maximum failure loads (P<.05). The highest mean failure load was obtained in the ICT group (1069 ±182 N), followed by the ITT (926 ±197 N), EHT (873 ±126 N), ITZ (568 ±81 N), EHZ (311 ±45 N), and ICZ (287 ±63 N) groups. ConclusionsAbutment material and connection design affected the fatigue survival of implant abutment assemblies. Implant abutment assemblies with a titanium-titanium interface revealed higher failure resistance than the implant abutment assemblies with a titanium-zirconia interface.

Fatigue Failure Load of Lithium Disilicate Restorations Cemented on a Chairside Titanium-Base.

To evaluate the fatigue failure load of distinct lithium disilicate restoration designs cemented on a chairside titanium base for maxillary anterior implant-supported restorations. A left-maxillary incisor restoration was virtually designed and sorted into 3 groups: (n = 10/group; CTD: lithium disilicate crowns cemented on custom-milled titanium abutments; VMLD: monolithic full-contour lithium disilicate crowns cemented on a chairside titanium-base; VCLD: lithium disilicate crowns bonded to lithium disilicate customized anatomic structures and then cemented onto a chairside titanium base). The chairside titanium base was air-abraded with aluminum oxide particles. Subsequently, the titanium base was steam-cleaned and air-dried. Then a thin coat of a silane agent was applied. The intaglio surface of the ceramic components was treated with 5% hydrofluoric acid (HF) etching gel, followed by silanization, and bonded with a resin cement. The specimens were fatigued at 20 Hz, starting with a 100 N load (5000× load pulses), followed by stepwise loading from 400 N up to 1400 N (200 N increments) at a maximum of 30,000 cycles each. The failure loads, number of cycles, and fracture analysis were recorded. The data were statistically analyzed using one-way ANOVA, followed by pairwise comparisons (p < 0.05). Kaplan-Meier survival plots and Weibull survival analyses were reported. For catastrophic fatigue failure load and the total number of cycles for failure, VMLD (1260 N, 175,231 cycles) was significantly higher than VCLD (1080 N, 139,965 cycles) and CDT (1000 N, 133,185 cycles). VMLD had a higher Weibull modulus demonstrating greater structural reliability. VMLD had the best fatigue failure resistance when compared with the other two groups.

Experimental study of stable crumb rubber asphalt and asphalt mixture

This study aims to analyze the road performance of plant-produced crumb rubber asphalt (PRA) based on wet process by comparing with base asphalt, styrene–butadienestyrene (SBS) modified asphalt, and field-produced rubber asphalt (FRA). Through infrared spectrum (IR) analysis and differential scanning calorimeter (DSC) tests, the microstructure of each binder were analyzed and compared. Dynamic Shearing Rheometer (DSR) with different test modes were utilized to analyze the rutting resistance and fatigue property of each binder while Bending Beam Rheometer (BBR) test was used to analyze the low-temperature properties of each binder. Asphalt mixtures were prepared with different binders and the road performances including high-temperature rutting resistance, low-temperature cracking resistance, moisture stability and fatigue failure resistance were evaluated. The findings indicate that the plant-produced crumb rubber asphalt shows good storage stability and satisfied road properties compared to other binders while the asphalt mixture prepared with plant-produced crumb rubber asphalt shows satisfied road performances. In general, the study indicates that the plant-produced crumb rubber asphalt could be a promising replacement for SBS modified asphalt based on the mixture type evaluated.

Function evaluation of asphalt mixture with industrially produced BOF slag aggregate.

Laboratory research suggested that basic oxygen furnace (BOF) slag-based asphalt mixture was a functional material. However, the BOF slag aggregate's quality was difficult to control when it was heavily used in entity engineering. The primary objective of this research was to evaluate the functional performances of asphalt mixture containing BOF slag coarse aggregate (BSCA), which was from an industrialized production line. Limestone mixture was a control group. The Marshall method was first adopted to design asphalt mixtures. The performances of limestone asphalt mixture and BOF slag asphalt mixture including fatigue failure resistance and moisture stability were then evaluated and compared. Results showed that the asphalt mixture containing BSCA possessed better durability, which meant the quality of BSCA from industrialized production lines was well controlled and this BSCA can be heavily used in entity engineering.

Suitability of rubber concrete for railway sleepers

Summary An experimental investigation by replacing 15% by volume fraction of fine aggregate by crumb rubber was conducted to find the fatigue failure load and impact resistance. The design strength of 50 and 55 MPa was achieved. Test result indicated that there was reduction in compressive strength and modulus values. The fatigue failure and impact resistance were high for rubber concrete when compared with ordinary high strength concrete. The impact strength for railway sleeper with crumb rubber replacement showed increase of about 60% when compared to prestressed concrete sleeper.

Microstructure and fatigue strength of high-strength Cu–Fe and Cu–V in-situ nanocomposite wires

The results of the quantitative analysis of the microstructure of the Cu–Fe and Cu–V in-situ nanocomposite wires with diameter of 0.44–0.80mm by transmission electron microscopy are presented. Comparative fatigue tests of Cu–Fe and Cu–V in-situ nanocomposite wires and pure copper samples have been carried out using a dynamic mechanical analyzer (DMA). The in-situ nanocomposites have significantly higher characteristics of low-cycle fatigue failure resistance as compared to that of pure copper. The fatigue crack propagation areas for the nanocomposite conductors and pure copper are characterized by fatigue striations and secondary cracking.