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Copyright of Journal of Harbin Institute of Technology. Social Sciences Edition / Haerbin Gongye Daxue Xuebao. Shehui Kexue Ban is the property of Harbin Institute of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Rare Metal Materials & Engineering is the property of Northwest Institute for Nonferrous Metal Research and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper analyses the phenomenon of fretting and fretting wear to the classical and modular total hip prostheses. Theoretical and experimental manifestations are studied, at the interface of the femoral stem with the bone cement mantle, at the taper junction between the femoral stem and the femoral head of the prosthesis, as well as at the tapering of the connections of the femoral neck adapter with the stem and the femoral head. The aim of the paper is to highlight the implications of modularisation of the total hip prosthesis femoral component, especially its tribological implications (fretting wear of modular junctions, fatigue and corrosion by fretting), which can contribute to increasing ion concentrations of the metal in the blood and the possibility of femoral stem fracture at the femoral head - neck junction. Experimental laboratory studies focused on the analysis of the tribological phenomena occurring at the taper junctions between the femoral head and neck, as well as the neck and femoral stem, highlighting the relevant qualitative tribological aspects. For this purpose, experimental junctions were fabricated and tested on a universal MTS mechanical machine, equipped with an Instron® fatigue testing device. The importance of the materials used for the taper (or trapezoidal) junction components and the measures to reduce the micro-motion, which reveal the phenomena of fretting, corrosion and fretting fatigue, are highlighted. The influence of tapering on tribological phenomena is also analyzed. [ABSTRACT FROM AUTHOR]

Copyright of Rare Metal Materials & Engineering is the property of Northwest Institute for Nonferrous Metal Research and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract Objectives Conical implant-abutment connections are popular for its anti-bending performance; on the other hand, the torsional and axial forces also play important roles in occlusion. However, so far there were scarce studies on their effects on connection stability. Therefore, this study seeks to investigate the mechanical performance of conical connections under different cyclic loading conditions. Methods 15 conical implant-abutment assembles (Cowell Medi, Busan, South Korea) were divided into 3 groups according to different cyclic loadings. In group BTA, the loading condition of the posterior occlusion was simulated (20–200 N, 30° off-axis and 4 mm eccentric to implant axis), generating a bending moment, a torsional moment, and an axial loading. In group BT, a bending moment and a torsional moment of the posterior occlusion were applied (10–100 N, 90° off-axis and 4 mm eccentric to implant axis). In group B, only a bending moment was applied (10–100 N, 90° off-axis and through implant axis). The fatigue testing machine ran at 10 Hz until failure, or to the upper limit of 106 cycles. The fatigue cycles and failure modes were recorded. Besides, the value of the torque loss of the abutment screw, the difference between initial torque and post-load reverse torque, was calculated. The data were statistically analyzed. Morphologies of the abutment conical surface were examined by scanning electron microscopy. Results In group B and BTA, all samples passed the test (106 cycles). While, in group BT, all abutments generated rotation within 140 cycles, showing significant differences compared to the other two groups (p < 0.001). However, from SEM observations, both group B and BT showed marked fretting wear, indicating obvious micromotion in the connection. Whereas group BTA showed indentation of tight contact, attributed to the axial loading. In terms of the torque loss of the abutment screw, the torque loss in group BT was much more than the other two groups with statistically significant differences (p < 0.05). Conclusion Owing to the effect of the bending moment, marked fretting wear was generated in the conical connections and further led to loss of the anti-torsional ability. However, adding an axial loading could improve their anti-torsional ability significantly. Graphical abstract fx1 Highlights • Effects of different loading conditions on conical connections are verified. • Bending moments generate fretting wear and undermine conical connection stability. • Adding axial loadings counteracts bending moments and stabilizes the connection. [ABSTRACT FROM AUTHOR]

An adaptive finite element simulation was developed to predict fretting wear in a head-neck taper junction of hip joint implant through a two dimensional (2D) model and based on the Archard wear equation. This model represents the most critical section of the head-neck junction which was identified from a 3D model of the junction subjected to one cycle of level gait loading. The 2D model was then used to investigate the effect of angular mismatch between the head and neck components on the material loss and fretting wear process over 4 million gait cycles of walking. Generally, junctions with distal angular mismatches showed a better resistance to fretting wear. The largest area loss in the neck after 4 million cycles of loading was 1.86E-02 mm 2 which was found in the junction with a proximal mismatch angle of 0.124°. While, the minimum lost area (4.30E-03 mm 2 ) was found in the junction with a distal angular mismatch of 0.024°. Contact stress, amplitude of sliding and contact length were found as the key parameters that can influence the amount of material loss and the process of fretting wear damage. These parameters vary over the fretting wear cycles and are highly dependent on the type and magnitude of the taper angle mismatch. This study also showed that lost area does not have a linear relationship with the mismatch angle of taper junctions. [ABSTRACT FROM AUTHOR]

Fretting wear at the dimple/gimbal interface of a hard disk drive suspension was investigated for stainless steel dimples in contact with stainless steel gimbals coated with diamondlike carbon (DLC) of different thicknesses and different elastic moduli. Scanning electron microscopy (SEM) was used to evaluate the size and characteristics of the wear scar of both the dimple and the gimbal. Fretting wear and fatigue-type cracks were found predominantly on the dimple. For different dimple/gimbal combinations tested in this study, the least amount of wear was obtained for the case of a 690 nm thick DLC overcoat. Numerical simulations were performed to calculate the maximum principal stress in the dimple and the gimbal with the goal of correlating wear and the maximum principal stress. The maximum principal stress in both the dimple and the gimbal was found to increase with an increase of the elastic modulus of the DLC overcoat on the gimbal. On comparing the experimental and simulation results, we conclude that wear and fatigue crack formation can be explained by the different level of the maximum principal stress in both the dimple and the gimbal. [ABSTRACT FROM AUTHOR]

We consider fretting wear in an adhesive contact due to tangential oscillations of small amplitude. While both wear in non-adhesive contacts and adhesive contacts without wear have been studied in detail, there still have been no attempts to combine both approaches. In the present paper, we study the problem of wear in adhesive contacts under the simplified assumption, that the adhesive (attractive) stress is constant up to some critical distance h and vanishes beyond this range (Dugdale approximation). In this approximation, the normal adhesive contact problem can be solved to a great extent analytically. In a series of previous works, it was shown that the worn shape due to fretting wear tends to some limiting shape which is determined solely by the solution of the normal contact problem. In the present paper, we exploit these ideas to derive the limiting shape of the worn body in an adhesive contact. [ABSTRACT FROM AUTHOR]

Structural parts in gas turbines undergo fretting wear, and as clearances open up, it turns into impact wear. Uncoated cobalt-based substrates that are used in such applications show poor resistance to fretting!impact damage and undergo extensive/unacceptable level of degradation. Commonly used substrate materials such as uncoated cobalt-based materials show poor resistance to fretting! impact wear. This study is focused on assessing the performance of high velocity oxyfuel (HVOF) tungsten carbide (WC) coatings and sintered tungsten carbide inserts as potential solutions for mitigating this issue. Sintered WC12Co with grain size range from 0.2 pm to 4.5 pm and HVOF coating with composition of WC-17%Co was tested. It was found that the HVOF coatings performed better than sintered material and the behavior was attributed to the hard WC particles surrounded by the higher volume fraction of cobalt binder. In the HVOF coating, the normal load was better accommodated by the decarburized WC but a fairly tough bindersurrounding matrix. An additional factor is that the sintered WC had significant volume fraction of undesirable W2C phase, which apparently underwent fracture during the test, thus showing an inferior behavior compared to the HVOF WC coating. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Harbin Institute of Technology. Social Sciences Edition / Haerbin Gongye Daxue Xuebao. Shehui Kexue Ban is the property of Harbin Institute of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Although cemented titanium alloy is not favored currently in the Western world for its poor clinical and radiography outcomes, its lower modulus of elasticity and good biocompatibility are instrumental for its ability supporting and transforming physical load, and it is more suitable for usage in Chinese and Japanese populations due to their lower body weights and unique femoral characteristics. Through various friction tests of different cycles, loads and conditions and by examining fretting hysteresis loops, fatigue process curves and wear surfaces, the current study investigated fretting wear characteristics and wear mechanism of titanium alloy stem–bone cement interface. It was found that the combination of loads and displacement affected the wear quantity. Friction coefficient, which was in an inverse relationship to load under the same amplitude, was proportional to amplitudes under the same load. Additionally, calf serum was found to both lubricate and erode the wear interface. Moreover, cement fatigue contact areas appeared black/oxidative in dry and gruel in 25% calf serum. Fatigue scratches were detected within contact areas, and wear scars were found on cement and titanium surfaces, which were concave-shaped and ring concave/ convex-shaped, respectively. The coupling of thermoplastic effect and minimal torque damage has been proposed to be the major reason of contact damage. These data will be important for further studies analyzing metal–cement interface failure performance and solving interface friction and wear debris production issues. [ABSTRACT FROM AUTHOR]

Spline couplings are often used in aerospace industry for the purpose of power and torque transfer. A spline coupling typically consists of a hub and shaft with internal and external teeth respectively. As the teeth are engaged and the spline coupling is put into operation, repeated relative surface movement of teeth begins and results in fretting wear. Principal component analysis (PCA) is a statistical technique to identify the important parameters and their relationships with each other. This work deals with the characterization of fretting wear by the help of principal component analysis. PCA has been applied to the experimental data obtained from fretting wear tests in the lab and important variables with respect to fretting wear identified. This serves as a new tool to interpret the experimental results and hypothesis generation in the field of fretting wear. [ABSTRACT FROM AUTHOR]

In this work the fretting wear in steam generator tubes of Incoloy ® 800 in contact with AISI 304, AISI 1060 and Cu (99,9%) pads acting in a cross-tube geometry was studied. Wear surface was characterized by scanning electron microscopy (SEM) and the resulting debris were characterized by transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS). It was verified that in all cases, the fretting conditions corresponded to gross slip. A predominance of adhesive wear was found for Cu and AISI 1060 while abrasive wear was predominant in the case of AISI 304. It was determined that the higher the hardness of the pad material the lower the surface damage (case of the AISI 1060). Analysis of debris allowed the identification non-stoichiometric oxide phases with either a spinel structure of the type FeCr 2 O 4 .Fe 3 O 4 and a hematite (Fe,Cr) 2 O 3 in the case of AISI 304, while for Cu and AISI 1060 pads, the presence of CuFe 2 O 4 spinel and (Fe,Cr) 2 O 3 hematite were observed, respectively. The formation of spinel structures originates in an effect of mechanical alloying between the surfaces. Debris particle size distribution was found to extend in the range from tens of nanometers to few micrometers with the larger particles consisting in agglomerates of crystallites with sizes between 5 and 20 nm . [ABSTRACT FROM AUTHOR]

We study the problem of wear of a rotationally symmetric profile subjected to oscillations with small amplitude. Under these conditions, sliding occurs at the boundary of the contact area while the inner parts of the contact area may still stick. In a recent paper, Dimaki with colleagues proposed a numerically exact simulation procedure based on the method of dimensionality reduction (MDR). This drastically reduced the simulation time compared with conventional finite element simulations. The proposed simulation procedure requires carrying out the direct and the inverse MDR transformations in each time step. This is the main time consuming operation in the proposed method. However, solutions obtained with this method showed a remarkable simplicity of the development of wear profiles in the MDR space. In the present paper, we utilize these results to formulate an approximate model, in which the wear is simulated directly in the one-dimensional space without using integral transformations. This speeds up the simulations of wear by further several orders of magnitude. [ABSTRACT FROM AUTHOR]

Biomechanical performance plays an important role in the long-term service of dental implants. Loosening and fatigue damage of the central screw are the most common problems. This research investigated the effect of the central screw taper angle on the loosening performance and fatigue characteristics of dental implants. Central screws with four taper angles, 30°, 60°, 90° and 180°, were processed and tested. The loosening performance of the screws under initial and postload conditions was compared. Then, the fatigue characteristics of dental implants was measured. Finally, the wear and fracture modes of the screws were observed. The damage locations were verified by finite element analysis (FEA). The results showed that the central screws with 30° taper had substantially better anti-loosening performance and less fretting wear. The central screws with 180° taper had a higher preload, resulting in a longer fatigue life. Furthermore, the fatigue fracture of the central screw occurred at the level of the first thread position, consistent with the FEA results. In the future clinical applications, central screws with a 30° taper angle may improve anti-loosening performance and prolong fatigue life by increasing the tightening torque. [Display omitted] • Four types of central screws with different mating taper angles were manufactured. • Reduction of the central screw taper improves resistance of dental implants to loosening. • A central screw with a high preload increases the fatigue life of dental implants. • Reduction of the central screw taper results in less surface wear after cyclic loading. • The fatigue fracture of the central screw mainly occurs at the level of the first thread. [ABSTRACT FROM AUTHOR]

This paper presents an efficient numerical method based on quadratic programming, which may be used to analyze fretting contacts in the presence of wear. The approach provides an alternative to a full finite element analysis, and is much less computationally expensive. Results are presented for wear of a Hertzian contact under full sliding and under partial slip. These are compared with previously published finite element analyses of the same problem. Results are also obtained for the fully worn problem by allowing a large number of wear cycles to accumulate. The predicted traction distributions for this case compare well with the fully worn analytical solution presented in part one of this paper. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, the characterization of contact surface damage due to fretting in a press-fitted shaft below the fretting fatigue limit is proposed by experimental methods. A series of fatigue tests and interrupted fatigue tests on the small scale press-fitted specimen were carried out by using rotating bending fatigue test machine. Macroscopic and microscopic characteristics were examined using scanning electron microscope (SEM), optical microscope or profilometer. It is found that fretting fatigue cracks were initiated even under the fatigue limit on press-fitted shafts by the fretting. The fatigue cracks of press-fitted shafts were initiated from the edge of contact surface and propagated inward in semi-elliptical shape. Furthermore, the fretting wear rates at the contact edge are increased rapidly at the initial stage of total fatigue life. After steep increasing, the increase of wear rate is nearly constant under the load condition below the fretting fatigue limit. It is thus suggested that the fretting wear must be considered on the fatigue life evaluation because the fatigue crack nucleation and propagation process is strongly related to the evolution of surface profile by fretting wear in the press-fitted structures. [Copyright &y& Elsevier]

Abstract: In mechanical engineering applications, cyclic loadings are most commonly seen. In many assemblies of moving components, contact problems under various lubrication conditions are lifetime-limiting. There, the relative motion of the contacting bodies combined with high loads transmitted via the contact surface leads to fretting fatigue and fretting wear failure. The present contribution gives first promising results within a long-term research project concerned with developing a methodological approach for the design and lifetime estimation of components under tribo-mechanical loading. [Copyright &y& Elsevier]

Abstract: This paper is concerned with the study of bolted joints undergoing fretting damage. The analysis has been prompted by an investigation into failures of wheel-hub assemblies in earth moving equipment. In such applications, premature failures of the wheels initiating at the wheel-hub connection is observed in service. Fretting fatigue and wear induced by flexural loading at the wheel-hub bolted joints are often deemed to be responsible for damage initiation and crack propagation. Ad hoc analytical formulations have been developed and implemented by the authors in order to capture the mechanisms which govern these phenomena. In this article we present a semi-analytical boundary element modelling technique, which combined with contact asymptotic techniques (BEM/CA) can be employed to assess the strength of bolted connections subjected to flexural loadings. [Copyright &y& Elsevier]

Abstract: The fretting friction coefficient between nickel titanium shape memory alloy (NiTi SMA) and hum Hank''s solution by SRV multi-functional test system. The results show that the friction coefficient between pairs decrease with the lubrication effect coefficient in the acidic and alkaline media is greater than that in the normal situation. The friction coefficient between the bone and NiTi SMA tends to be stable with the increase of the amplitude in the four media. Because Hank''s solution restrains the forming of worn scrap and its further development, the maximum wear depth and width of worn scrap and the volume of worn spot decrease to some extent compared to that in normal situations. [Copyright &y& Elsevier]

The current study presents the results and effects of fretting wear on rolling contact fatigue (RCF) life of M50 bearing steel. A fretting wear test rig was designed and developed to induce fretting scars on the surface of standard M50 rods commonly used in a three ball and rod RCF testing machine. The fretting machine was used to induce fretting scars at a Hertzian contact pressure of 1.1 GPa, in the presence of MIL-L-23699 lubricant at a frequency of 10 Hz, slip amplitude of 21 µm for different number of cycles. The fretted rods were then evaluated at a contact pressure of 1.7 and 3.4 GPa in the three ball and rod RCF tester to determine the effect of fretted scar on fatigue life. The results indicate that a fretting scar can reduce the fatigue life at 3.4 GPa by an average of 30 per cent and fretted rods operating at 1.7 GPa behave very similar to an unfretted rod operating at 3.4 GPa. [ABSTRACT FROM AUTHOR]

The stem-cement interface experiences fretting wear in vivo due to low-amplitude oscillatory micromotion under physiological loading, as a consequence it is considered to play an important part in the overall wear of cemented total hip replacement. Despite its potential significance, in-vitro simulation to reproduce fretting wear has seldom been attempted and even then with only limited success. In the present study, fretting wear was successfully reproduced at the stem-cement interface through an in-vitro wear simulation, which was performed in part with reference to ISO 7206-4: 2002. The wear locations compared well with the results of retrieval studies. There was no evidence of bone cement transfer films on the stem surface and no fatigue cracks in the cement mantle. The cement surface was severely damaged in those areas in contact with the fretting zones on the stem surface, with retention of cement debris in the micropores. Furthermore, it was suggested that these micropores contributed to initiation and propagation of fretting wear. This study gave scope for further comparative study of the influence of stem geometry, stem surface finish, and bone cement brand on generation of fretting wear. [ABSTRACT FROM AUTHOR]

Friction andwear properties of Si6-Z AlzOzN8-Z (z = 0.5) were studied in case of fretting. SiAlON samples were prepared by hot pressing without any externally added liquid. The effect of running time, slip amplitude, and normal load on friction and wear were investigated. A constant coefficient of 0.45 was observed during running time; however, friction coefficient increased from 0.445 to 0.475 for normal load variation of 20N to 60N. Wear increased linearly with the increase in sliding time and normal load for both SiAlON and steel; however, it decreased with the increase in slip amplitude. Higher wear was observed at low amplitudes as compared with wear at higher amplitudes. Transition from higher wear to lower wear occurred at fretting amplitude of 100-150üm. Wear coefficient of 7.0 x 10-4 and 18 x 10-4 was observed for SiAlON and steel, respectively. Micrographs proved useful for understanding wear mechanism. The wear in SiAlON/steel tribopair was caused by a combination of third body abrasion, tribofilm formation, and minor scoring. [ABSTRACT FROM AUTHOR]

The paper presents a numerical model to investigate fretting wear either under partial or gross slip conditions. An efficient three-dimensional elastic-static contact model to solve both the normal contact problem and the tangential contact problem is presented. The contact model is validated with analytical solutions for a sphere on flat geometry. A wear law issued from the literature and based on the friction energy is used to simulate surface wear. Numerical friction logs are obtained and the wear rate evolution is found to be highly dependent on the tangential displacement. [ABSTRACT FROM AUTHOR]

Fretting wear characteristics of Molybdenum disulphide (MoS2)-bonded solid lubricant coating on structural steel, AISI 4340, when fretted against hardened-tempered bearing steel, AISI 52100 are reported in this paper. Fretting wear tests were conducted at different normal loads and at constant slip amplitude of 60 μm. Coefficient of friction under fretting conditions and wear resistance were measured. The MoS2-bonded solid lubricant offers improved fretting wear resistance against bearing steels. Substrate hardness has influenced the coating behaviour at high loads. The fretting wear resistance also depends upon the normal load and the nature of contact, stick slip, or gross slip. [ABSTRACT FROM AUTHOR]

The stem-cement interface experiences fretting wear in vivo due to low-amplitude oscillatory micromotion under physiological loading, as a consequence it is considered to play an important part in the overall wear of cemented total hip replacement. Despite its potential significance, in-vitro simulation to reproduce fretting wear has seldom been attempted and even then with only limited success. In the present study, fretting wear was successfully reproduced at the stem-cement interface through an in-vitro wear simulation, which was performed in part with reference to ISO 7206-4: 2002. The wear locations compared well with the results of retrieval studies. There was no evidence of bone cement transfer films on the stem surface and no fatigue cracks in the cement mantle. The cement surface was severely damaged in those areas in contact with the fretting zones on the stem surface, with retention of cement debris in the micropores. Furthermore, it was suggested that these micropores contributed to initiation and propagation of fretting wear. This study gave scope for further comparative study of the influence of stem geometry, stem surface finish, and bone cement brand on generation of fretting wear. [ABSTRACT FROM AUTHOR]

This paper presents an approach to the remaining life prediction of steam generator (SG) U-tubes, which are intact initially, subjected to fretting-wear degradation due to the interaction between a vibrating tube and a foreign object in operating nuclear power plants. The operating SG shell-side flow field conditions are obtained from a three-dimensional SG flow calculation using the ATHOS3 code. Modal analyses are performed for the finite element models of U-tubes to get the natural frequency, corresponding mode shape, and participation factor. The wear rate of a U-tube caused by a foreign object is calculated using the Archard formula, and the remaining life of the tube is predicted. Also discussed in this study are the effects of the tube modal characteristics, external flow velocity, and tube internal pressure on the estimated results of the remaining life of the tube. [ABSTRACT FROM AUTHOR]

The fretting corrosion tests on a hall-on flat contact of pure titanium were carried out under the media of distilled water and Saline solution on a hydraulic fretting tester with high precision. On the base of the dynamics analyses of fretting behaviours, the surface morphologies and wear volume of fretting scars were examined by laser confocal scanning microscope (LCSM). The results indicate that the friction coefficients are reduced and the positions of fretting regimes are changed by aqueous media of distilled water and Saline solution. The wear volume is the smallest under the condition in air. The friction coefficient and wear volume increase with the increase of the displacement in all three media. The fretting wear mechanisms exhibite mainly the combination of adhesive wear and delamination. The synergy of corrosion and wear in aqueous media accelerates evidently the material loss of titanium. [ABSTRACT FROM AUTHOR]

AISI 304 austenitic stainless steel was ion implanted with tungsten and the improvement in surface hardness and fretting wear was investigated. The W ion implantation was carried out using a metal vapor vacuum arc (Mevva) ion source, with a mean energy of 105 ke V under a current density of 22 µA/cm² and at doses of 3 x 1017 cm² … 5 x 1017 cm². Micro-hardness and {retting wear of the implanted samples were measured and compared to the unimplanted substrate. The area of fretting scar was decreased by 32% to 48% after W ion implantation, which should be attributed to the hardening effects and high compressive residual stress generated by ion implantation. Owing to the defect hardening and solution hardening, the near-surface hardness was improved by a {actor of three after the ion implantation. [ABSTRACT FROM AUTHOR]

The frictional contact conditions in a helical spline joint coupling under torsional and axial loads are studied using finite element analyses. Comparisons of spline root torsional stresses are made with photoelastic measurements. Surface contact tractions, relative slip distributions and subsurface localized stress component and equivalent stress distributions are presented for both the external and the internal spline contact surfaces. The work is important as a basis for understanding and predicting the fatigue, contact fatigue, fretting fatigue, wear and fretting wear characteristics of the coupling. A representative test specimen concept is presented which seeks to capture the local contact variable distributions in the spline coupling, with a view to predicting the wear and the contact and fretting fatigue performance of the coupling. [ABSTRACT FROM AUTHOR]