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An experimental program was conducted that simulated an internal rod failure to review re-anchoring ability, transfer length, and residual bond strength of grouted post-tension anchors with high rod to duct area ratios under in-situ conditions. Additionally, a theoretical model founded on interference fit, initial assumptions, and debris wedging was expanded to include a concrete to pipe interface. The experimental program included three full scale concrete specimens, whose length, annulus space for grout, and anchor diameter were nearly identical to existing anchors within dams in California. The specimens were instrumented along the anchor and concrete to capture strains in the longitudinal and transverse directions, the values of which, were compared against the theoretical model and found to be in good agreement along with the measured transfer length values. The debris wedging ratio found was consistent across the specimens and closely resembles the ratio captured in a similar study by the authors. • Consideration of initial conditions for re-anchoring of grouted post-tension anchors. • Proposed input / consideration of debris wedging. • Interference fit calculation procedure for a multilayer anchorage system. • Experimental comparison with theoretical model for cleaned and uncleaned specimens. [ABSTRACT FROM AUTHOR]

The research on how to reduce energy consumption and improve the efficiency of amorphous motors has extensive coverage. This study systematically investigates the influence of internal stress induced by impregnation curing and interference fit on the soft magnetic properties and loss characteristics of Fe80Co3Si3B10P1C3 (CAF4) amorphous alloy iron cores. The amorphous iron core samples undergo analysis through differential scanning calorimetry (DSC), transmission electron microscopy (TEM), X-ray diffraction (XRD), magnetic performance testing equipment, flexible pressure sensors, and magnetostriction testers. The CAF4 amorphous iron core after impregnation curing (AIC) exhibits the lowest loss of P1.2T,1.5 kHz = 22.8 W/kg when annealed at 260 °C, representing a 21% increase compared to the pre-impregnation curing (BIC) state. Within the commonly utilized interference fit range, the loss growth rate of CAF4 amorphous iron cores is lower than that of Fe80Si9B11 (1K101). Likewise, at a frequency of 50 Hz and an excitation of 1000 A/m, the magnetostriction coefficient of CAF4 is smaller than that of 1K101. Within the typical interference fit range, the magnetization performance of CAF4 amorphous iron cores surpasses that of 1K101, favoring lightweight and compact motor designs and reducing copper losses. Consequently, CAF4 amorphous iron cores exhibit significant advantages when employed in motors.

A high-speed permanent magnet motor is the core driving component of a centrifugal air compressor. The power of the centrifugal air compressor is output by the motor. Its safety and reliability are embodied in the stability of the rotor structure, which greatly affects the stability and working efficiency of the centrifugal air compressor. Much research has focused on the material strength, structural characteristics, and fit clearance of a high-speed rotor, whereas few research articles have focused on the influence of interference fit of high-speed and ultra-high-speed permanent magnet motors, and there is also little research on the thermal failure caused by temperature in high-speed motors. In this paper, the influence of the interference fit and temperature of the high-speed permanent magnet motor is studied. Using finite element analysis conducted by Ansys to obtain simulation data, the influencing factors of the strength of the interference are analyzed comprehensively in the centrifugal compressor rotor system. The interference value and rotational speed range are determined via numerical calculation. Under the condition of minimum interference, when the calculated speed reaches 137,628.82 rpm, the structure of the rotor is loose and fails, which is a mechanical failure caused by the relative sliding of the magnet and the sheath. The calculated speed value differs from the simulation result by about 1.2%. The simulation results show that the maximum stress of the structure can be reduced from 1186.1 MPa to 308.42 MPa by adding chamfer to the end covers in interference fit structure. The effects of interference value, rotational speed, temperature, and sheath thickness on the structure are also analyzed. From the perspective of temperature on structural reliability, the failure temperature of the structure decreases when the interference value increases. The lowest failure temperature is 182.3 °C when the interference value is 70 μm. After that, the interference value increases and the failure temperature increases. The reason for this is the interaction between radial stress and contact stress. These results are caused by the interaction between interference fit and temperature, which should be paid attention to when the structure of a high-speed permanent magnet motor is designed.

Mechanical couplings in engineering usually use interference fits to connect the shaft and hub. A railway wheel axle is a press fit that is connected by interference and can be subjected to bending stress. In loaded press fits, a high concentration of contact stresses can be generated in the area of the axle-fillet beam, which in most cases leads to the failure of the axle due to fatigue and fretting fatigues. Therefore, it is crucial to determine the ability of the press-fitted joints to provide sufficient frictional resistance that can withstand the loads and torques by evaluating the safety factor, especially when the mechanical or structural system is loaded. In this paper, the contact pressure and stress distribution along the radius of the wheel axle are studied using the analytical calculation of Lame’s equation, and the numerical method used is by ANSYS software. It was found that interference fits have a great influence on the connection strength of interference fits, which are directly related to the contact pressure. Increasing the interference increases the contact pressure, which allows higher torque and load capacity to be transmitted. The finite element analysis showed good agreement for the highest interference value of 230 µm with a relative error of 1.4%, while this error increased to the maximum relative error of 14.33% for a minimum interference of 100 µm.

The working conditions of self-aligning bearings in rolling mills are complex. The actual life of the bearing often does not reach the design life as expected. Therefore, it is of great significance to study the global load distribution and local stress distribution of self-aligning roller bearing. The global model involving contact of a number of elements often results in a long calculation time and convergence difficulty. Firstly, proposes a new simplified finite element model of bearing based on Hertz contact theory, which can greatly improve the calculation efficiency. Then, the roller contact loading distribution of the global model is solved based on the interference fit amount of the shaft and the inner ring of the bearing. Finally, the displacements corresponding to the maximum contact load is used as the boundary conditions of the local model, and the stress distribution of the inner ring is solved. The results show that the loading ratio of the two rows of raceways and loading distribution of the contact are varied with working conditions. The interference fit amount specified in the present study makes the minimum Mises stress of the inner ring greater than 40 MPa. This will reduce the strength and fatigue life of the bearing.

Cylindrical keyed joint fits used in various assembly units of industrial machinery and agricultural machines have been considered. In most cases, these are clearance, less often, transitional fits due to the assembly and disassembly velocity criterion in this type of connection. In the clearance fits, wear occurs due to the initial relative surface movements, as well as abrasive and wear products occurring in the friction zone. The larger the clearance, the smaller the contact area, the higher the specific pressure, the greater the microshear velocity, the greater the number of contaminants in the contact zone, and the more intensive the surface wear. If there is clearance in the cylindrical fit, the key begins to move along the horizontal and vertical planes, thus leading to increased surface wear and crushing in the key connection with the shaft groove and the bushing groove. Given that the purpose of keyed joints in agricultural machinery is the transmission of large loads, it is recommended to use an interference fit of H7/s7, H8/х8, H8/u8, and H8/s8 to improve the durability substantially. The recommended interference fits have been compared in terms of the interference values in the sprocket shaft joint of the unified reducer H090.20, where 30H7/h9 was earlier used. Even with the highest interference fits, it is possible to dismantle the pressed cylindrical connection using manual pullers. [ABSTRACT FROM AUTHOR]

During cementless total knee arthroplasty (TKA), an overlap between the resected tibia and the implant's geometry, termed interference fit, is introduced to facilitate primary stability and direct bone-implant contact. However, little is known about the actual interference achieved and the resulting mechanical response in the surrounding cancellous bone. The aim of this study was (1) to experimentally quantify the actual interference achieved for a commercially available cementless tibial implant and (2) to assess its effect on the post-impaction cancellous bone strain. Seven human cadaveric tibiae were micro-CT scanned intact (23 µm/pixel), once prepared for TKA (46 µm/pixel) and following implantation (46 µm/pixel). The actual interference across the entire bone-implant interface was quantified and, via digital volume correlation, the compressive strains of bone in contact with the implant and at increasing distance, were extracted. An inhomogeneous actual interference was found across the implant pegs and keel (median ± std dev: 0.70 ± 0.27 mm), which was lower than the intended. Limited interference (0.02 ± 0.12 mm) was found directly under the baseplate, with immediate bone-baseplate contact of 54%. The induced compressive strains were related to the actual interference within 3.14 mm from the bone-implant interface (R 2  = 0.269-0.450, p < 0.001), with higher compressive strains corresponding to higher interference, but not being related to the bone volume fraction. Clinical Significance: Insight is provided into the interaction between the variability of the resection and the resulting mechanical environment. A complex relationship is apparent, whereby the actual interference accounted for up to 45% of the variation in induced compressive strain magnitude., (© 2024 Orthopaedic Research Society.)

Interference fits are generally used in mechanical systems because they have low-cost production and their assembly parts are much smaller than other mechanical joints. Also, their geometric shapes and material properties allow technicians to actively determine how strong the fits are. In this study, let's present research on interference fits between steel and brass assembly parts. The experimental processes were accomplished with five pairs of specimens to evaluate the behaviours of surface asperities under a high loading condition. Specifically, the specimen pair includes a C45 steel shaft and a C2680 brass hub, which have different surface roughness values (Ra). Let's apply high-precision methods in measuring all dimensional parameters and employed axial load tests for distinctively inspecting the steel-brass interference fit performance. In every experiment, the measured responses are: 1) the surface roughness values (Ra) before and after loading cycles; 2) the axial load (Fa); 3) the relative displacement value or the real-time interface length in loading stages (l). The aim of this study is to propose a new relative interference value specifically between steel and brass assembly parts, which can help determine the interference loss value more accurately. It was concluded that with the relative interference of 2.25 ‰ the load capability of steel-brass interference fits is extended. Besides, let's narrow down the predictive loss coefficient (a) for steelbrass interference assemblies ranging from 1.1 to 2.1, which varies from widely used standards considering α = 3. This result helps minimize inaccuracies in interference fit designs, calculations, and work capabilities. [ABSTRACT FROM AUTHOR]

This article focuses on solving the problem of precise peg-in-hole assembly. The main contribution of this article is to propose a control method to improve the assembly precision. The method is capable to realize the precise insertion assembly tasks of cylindrical or prismatic objects with clearance or interference fit. In this article, a feature space and a response space are first constructed according to the relative pose and equivalent forces and moments. Then, the contact states are segmented in the feature space and the segmentation boundaries are mapped into the response space. Furthermore, a feature-based compliance control (FBCC) method is proposed based on boundary mapping. In FBCC method, a direction matrix is designed to execute accurate adjustment and an integral element is applied to eliminate residual responses. Finally, the simulations and experiments demonstrate the superiority and robustness of FBCC method. [ABSTRACT FROM AUTHOR]

A device is proposed for determining the pressure in a joint based on an interference fit. Its sensitive element consists of balls located between the contacting surfaces. Two types of contact interaction between the balls and the components of the joint are considered: elastoplastic deformation of the balls; and elastoplastic deformation of the parts. The pressure in shaft–bush contact is determined from the deformation. [ABSTRACT FROM AUTHOR]

Gears mounted on a shaft via interference fit are the subject of an internal pressure which is essential for power transmission between gear and shaft. The pressure between shaft and gear is responsible for additional stresses occurring both in shaft and gear. This study examines the effect of stresses arising due to the interference on the crack growth that exists at the root of the gear tooth. The numerical analyses were conducted on models having different rim thicknesses by using the extended finite element method that allows mesh-independent crack modeling and does not need re-meshing. The results showed that internal pressure yields additional stresses in the tangential direction. The increment in tangential stress changed the location and intensity of the maximal 1st principal stress and accelerated crack growth. As the tightness of the fit increased, the crack turned towards the rim rather than towards the tooth. As the crack growth through the rim may cause a catastrophic failure of gear, the increment in tangential stress due to internal pressure is crucial for the fatigue life of the gear. [ABSTRACT FROM AUTHOR]

• Considering the disc-shaft nonlinear contact, the finite element model of rotor system is established. • Newmark-β and Newton-Raphson methods are used to solve the dynamic response. • The established dynamic model considers the variation of disc-shaft contact state. Typically, the interference fit is used to perform the tight junction between disc and shaft. Nevertheless, the nonlinear contact between disc-shaft is neglected in tradition research. Hence, aimed at the shortcoming, considering the nonlinear contact between disc-shaft, the finite element model of rotor system featured with coupling parallel misalignment is established based on Timoshenko beam theory. Firstly, due to the nonlinear of disc-shaft contact, Newmark-β method is employed to combine Newton-Raphson method to solve the dynamic response. Then, according to the comparative analysis between dynamic characteristics of rotor systems operated with three conditions, the concretely discussion on the effect of initial interference and parallel misalignment degree are performed. The results show that disc-shaft nonlinear contact can cause the slight collision between disc-shaft, and the existence of parallel misalignment can intensify the slight collision. Besides, as rotation speed up, the contact states between disc-shaft become the process of repeated cycles: separation, contact, and then separation. Finally, the experiment study is conducted, and the concluded that the experiment result is corresponding to the simulation result can be obtained. It is established that the research results can provide possibilities for the identification and diagnosis of the rotor system with disc-shaft nonlinear contact. [ABSTRACT FROM AUTHOR]

Remanufacturing has been gaining increasing attention in the last few years as a part of green engineering. It is the process of restoring the original specifications of a given product utilizing a combination of new, repaired, and old parts. The present study investigates non-destructive disassembly of an interference fit pin-hub joint to enable the reuse of worn parts with the same loading capacity. The aim is to reduce the disassembly force while preventing plastic deformation and frictional damage on the contact surface to avoid fretting failure and enable further coating. A finite element model of a shaft/hub interference fit was developed, taking into account two cases of damage to the mating parts: deformation and corrosion. The results indicate that thermal disassembly is effective in reducing breaking force by 50% in deformed joints, whereas vibration waves are more suitable for corroded parts with increased friction. In addition, applying a low-frequency oscillation force to the axis of disassembly reduces the pulling out force by 5% and plastic deformation by 99% due to acoustic softening effects. Furthermore, using a heat flux simultaneously with vibration decreases the breaking force by 85%, indicating the higher effectiveness of thermal-aided disassembly and vibration-assisted disassembly in reducing the breaking force of corroded parts with increased friction. This study provides remanufacturing designers with efficient tools to weaken the interference fit and decrease the disconnecting force, ultimately reducing the cost and time required for the disassembly process.

Fretting fatigue is a fatigue damage process that occurs when two surfaces in contact with each other are subjected to relative micro-slip, causing a reduced fatigue life with respect to the plain fatigue case. Fretting has now been studied deeply for over 50 years, but still no univocal design approach has been universally accepted. This review presents a literature study that involves the three main types of mechanical joint affected by fretting fatigue (press-fitted shaft hub joints, dovetail joints, and bolted joints) aiming at giving insight into the progress made in terms of design guidelines for engineers. [ABSTRACT FROM AUTHOR]

Heated-mandrel winding is the main process of modern composite material molding because of its characteristics of winding and curing in one step. Winding tension is a key factor in the molding process and has an important impact on the molding effect. Excessive winding tension will cause the inner looseness and outer tightening, and too small winding tension will cause the outer looseness and inner tightening. In short, the stratification will occur during the curing as long as the winding tension value is not set properly, which will seriously affect the molding quality of composite materials. The tension system of single winding process is difficult to apply to the heated-mandrel winding process because winding and curing are separate in the traditional single winding process, there is no need to consider the diversification of parameter state caused by curing reaction in winding process. In the heated-mandrel process, the balance of forces between adjacent layers is broken, the stress changes in adjacent layers affected by the temperature field are considered during winding. The tension values are obtained by adopting the tension system model established in this paper and the traditional finite element iterative search calculation method is replaced by numerical analysis method. An analytical algorithm for the method of winding with tension as the interference fit of the thin layers is adopted in the calculation procedures and the nonlinear tension solution problem is converted into a linear displacement-stress calculation problem. The lengthy and complicated traditional tension calculation method is simplified. [ABSTRACT FROM AUTHOR]

The decrease of stress amplitude is generally believed as the mechanism of fatigue life enhancement in interference fit joints under cyclic loading for each load cycle. In order to exactly estimate it, a new analytical model was presented. In this model, influences of mass, geometry, and plastic deformation are considered to modify and improve the spring model, and, moreover, the stress amplitude at the smallest crossing section is investigated. Taking these factors into account, stress amplitude decrease of various interference values can be calculated more accurately; therefore, the analytical solutions have good agreement with the finite element numerical and experimental results under different interference values and load levels. The analytical model indicates that the decrease ratio of stress amplitude is of a certain value for a specific interference value with the external load under the critical value. Furthermore, the decrease ratio of stress amplitude mainly depends on the stiffness of the pin and plate, which is mostly affected by the geometric shapes and plastic deformation ranges of the pin and plate. In addition, raising the interference value leads to larger stress amplitude reduction since the plastic deformation areas expand with the increment of interference values. [ABSTRACT FROM AUTHOR]

Studies on load capacity enhancement for an interference fit mainly focused on the essential coupling material pair of steel–steel parts. With more complex requirements in technical assemblies, more notable cases of material pairs are applied in interference fits. Hence, it is crucial to highlight the variations across-coupling scenarios in order to identify a workable approach for load capacity augmentation. The goal of this study is to examine how nickel plating affects the interference fit between steel and brass assembly parts. The experiments in this research focus on comparing the load capacity of plated and non-plated specimens by evaluating the extraction force on a compression machine. The fit parameters are measured with a coordinate measuring machine and contact surface profiler. Some microscopic observations are made to confirm the phenomena of this coupling case. The axial extraction tests determined that the plated fits show an increase in axial force limits of around 20% in comparison with the non-plated ones. There are also some significant improvements in the plated shaft surface properties, which reduce the physical adhesions between the shaft and hub. These results confirm the possibility of reusing the plated assembly parts, which gives highly economic and environmental advantages.

Taking the double-cone expansion joint sleeve (EJS) as an example, this paper proposes a hybrid prediction method of load-carrying capacity considering the displacement boundary conditions of EJS and rotation angle of spindle, and a comprehensive optimization method for the structure of EJS is established using this method. Firstly, based on the thick-walled cylinder theory and considering the displacement boundary conditions of interference contact surface, a new calculation method for calculating torque is presented, and the main parameters affecting load-carrying capacity are determined. Secondly, the finite element method is used to simulate assembly process and working process of EJS to obtain the ultimate torque, the effects of inner ring, outer ring, taper, elastic modulus, and friction coefficient are investigated. Based on the hybrid prediction results of load-carrying capacity, the multi-objective optimization is carried out using genetic algorithm through the construction of orthogonal experimental combination, the optimization of structural parameters of EJS is realized. The results indicate that the maximum equivalent stress is reduced by 20.88 %, the ultimate torque is increased by 0.23 %, and the mass is reduced by 5.11 %. It is proved that the method can effectively reduce maximum equivalent stress and solve design defects caused by stress concentration. [ABSTRACT FROM AUTHOR]

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This paper deals with the multi-objective intelligent cooperative optimization for interference fit of conical sleeve. The influence of various factors on contact pressure of conical sleeve was quantitatively analyzed, and the relationship among multi-objectives and multivariables was comprehensively built. Take the cone sleeve of oil film bearing as the research object, the key factors of the cone sleeve were determined with a combination of actual situations, and its sample data was obtained by central composite test design. Considering the multi-objective involving yield strength, torque and mass, the approximate model of the response surface based on the kriging algorithm was given. Then, a multi-objective intelligent cooperative design method for interference fit of the cone sleeve was established by solving the NSGA-II algorithm. Example analysis has shown that such a method makes up for the deficiency of theoretical design to ignore the stress concentration problem, and its accuracy is 32 times that of the BP neural network algorithm. Finally, the experiments verified the correctness of this method. [ABSTRACT FROM AUTHOR]

Gears are commonly used in transmission systems to adjust velocity and torque. An integral gear or an interference fit could be used in a gearbox. Integral gears are mostly preferred as driving gear for a compact design to reduce the weight of the system. Interference fit makes the replacement of damaged gear possible and re-use of the shaft compared to the integral shaft. However, internal pressure occurs between mating surfaces of the components mated. This internal pressure affects the stress distribution at the root and bottom land of the gear. In this case, gear parameters should be re-considered to assure gear life while reducing the size of the gear. In this study, interference fitted gear-shaft assembly was examined numerically. The effects of rim thickness, profile shifting, module and fit tolerance on bending stress occurring at the root of the gear were investigated to optimize gear design parameters. Finite element models were in good agreement with analytical solutions. Results showed that the rim thickness of the gear is the main parameter in terms of tangential stress occurring at the bottom land of the gear. Positive profile shifting reduces the tangential stress while the pitch diameter of the gear remains constant. Also, lower tolerance class could be selected to moderate stress for small rim thickness. [ABSTRACT FROM AUTHOR]

To solve the problem of separation of armature and rail at the tail of a quadrupole armature arm at the initial contact, the causes of separation are analyzed based on simplifying the armature arm into a cantilever beam. At the same time, to obtain the contour curve of the armature arm, a reverse loading method is proposed, and the rationality of this method is verified. In view of the shortcomings of the reverse loading method, an improved method of using finite element simulation to predict the deflection of the armature arm is proposed. The results show that the curve of the armature arm obtained by the improved reverse loading method is, at initial contact, without contact separation at the tail. The contact area and contact efficiency of the armature arm are significantly improved, and the pressure distribution on the contact surface is more uniform, which provides an effective contact state for pulse current. [ABSTRACT FROM AUTHOR]

Abstract When the gearbox body interference is connected to the ring gear, prestressing occurs in the ring gear, which has a significant impact on the strength and life of the gear. Research on the prestressing of the inner ring gear is in the preliminary stage, and the distribution rule of the prestressing and the influence of each parameter on the interference prestressing have not been derived. In this paper, based on the method of calculating the prestressing of the thick cylinder in interference fit, the ring gear is found to be equivalent to a thick cylinder, and the distribution rule of prestressing of the ring gear in the interference fit is inferred. Then, by modeling and analyzing the gearbox body and ring gear in the interference fit using ABAQUS, the distribution rule of prestressing the ring gear in the interference fit is obtained through a numerical simulation. Finally, the prestressing of the ring gear in the interference fit is measured using X-ray diffraction, and the distribution rule of prestressing of the ring gear in the interference fit is obtained through analysis. Compared with the distribution rule of prestressing in theory, numerical simulation, and experiment, the theoretical distribution rule of prestressing is amended through a statistical method, and a more accurate formula of prestressing is obtained. Through the calculation of the stress and bending moment in the dangerous section of the ring gear through prestressing, the formula for checking the tooth root flexural fatigue strength in the interference fit prestressing is inferred. This research proposes a tooth root bending strength conditional formula for the inner ring gear of the interference fit, which serves as a guide for the design and production of the actual interference joint inner ring gear.

The vibration of ceramic motorized spindle determines the machining quality of CNC machine tools. The dynamic characteristics of a motorized spindle were explored under the influence of interference fit and thermal displacement. Using heat transfer theory and bearing Harris theory, the temperature field model of motorized spindle was established, which aims to find the relationship of thermal displacement and interference. In addition, the dynamic and thermal factors were coupled to the dynamic model of the ceramic motorized spindle rotor system, of which the variation rules of bearing stiffness and rotor vibration characteristics were calculated and analyzed. The accuracy of the motorized spindle rotor system dynamic model was verified by experiments. The results show that the interference fit of shaft and bearing decreases with the rotating speed increase under the combined influence of centrifugal force, load and thermal displacement. The vibration was calculated by the dynamic model of motorized spindle rotor system considering dynamic and thermal factors. The maximum error was 3.9 %, which is well consistent with the experimental results. The dynamic characteristics of ceramic motorized spindle can be improved by appropriately increasing the degree of interference tightness at high speed. [ABSTRACT FROM AUTHOR]

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In order to overcome ablation on the rail–armature contact region and increase electromagnetic thrust force, a structure of armature arm with interference fit is designed in augmented quadrupole electromagnetic launcher (EML). Good contact characteristic between the armature and rails plays an important role in the success of EML. The electromagnetic-structure coupling model based on the finite element analysis is presented to investigate the contact characteristic, the distribution of current density, and the electromagnetic force (EMF) and the contact pressure is given, which indicates the EMF needs to be loaded unevenly on the armature arm. Finally, based on electromagnetic-structure coupling model, some important parameters including the contact area, the contact efficiency, the contact counterforce, and maximal contact pressure are analyzed with the different interference, different length, and different thickness of armature arm after the pulse current is loaded. The dependences of nonuniform contact parameters on the nonuniform EMF are obtained. [ABSTRACT FROM AUTHOR]

Background: Uncemented femoral stem insertion into the bone is achieved by applying successive impacts on an inserter tool called "ancillary". Impact analysis has shown to be a promising technique to monitor the implant insertion and to improve its primary stability., Method: This study aims to provide a better understanding of the dynamic phenomena occurring between the hammer, the ancillary, the implant and the bone during femoral stem insertion, to validate the use of impact analyses for implant insertion monitoring. A dynamic 3-D finite element model of the femoral stem insertion via an impaction protocol is proposed. The influence of the trabecular bone Young's modulus (E t ), the interference fit (IF), the friction coefficient at the bone-implant interface (μ) and the impact velocity (v 0 ) on the implant insertion and on the impact force signal is evaluated., Results: For all configurations, a decrease of the time difference between the two first peaks of the impact force signal is observed throughout the femoral stem insertion, up to a threshold value of 0.23 ms. The number of impacts required to reach this value depends on E t , v 0 and IF and varies between 3 and 8 for the set of parameters considered herein. The bone-implant contact ratio reached after ten impacts varies between 60% and 98%, increases as a function of v 0 and decreases as a function of IF, μ and E t ., Conclusion: This study confirms the potential of an impact analyses-based method to monitor implant insertion and to retrieve bone-implant contact properties., Competing Interests: Declaration of competing interest No conflict of interest declared, (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Fretting fatigue is a fatigue damage process that occurs when two surfaces in contact with each other are subjected to relative micro-slip, causing a reduced fatigue life with respect to the plain fatigue case. Fretting has now been studied deeply for over 50 years, but still no univocal design approach has been universally accepted. This review presents a literature study that involves the three main types of mechanical joint affected by fretting fatigue (press-fitted shaft hub joints, dovetail joints, and bolted joints) aiming at giving insight into the progress made in terms of design guidelines for engineers.

Contact pressure is stronger nonlinear along assembled length and hard to calculate in the interference fit with closed structure and micro dimension. A new method based on thin wall shell theory is presented to analyze the assembly pressure by solving integral equation. A simple model which is an assembly between thin wall cylinder with a fixed end and a rigid rotating shaft is solved. The results are compared with the results from ANSY,and in nice agreement. This method is easy to be applied on the design of the micro and high speed rotating machine.

At present, the high lock bolt assembly standard of our country are come from abroad, lack of relevant theoretical and experimental research. Fatigue gain mechanism of high lock bolt interference on the base of different layer thickness is researched,through the method of combining the fatigue test and finite element simulation in a certain type of aircraft aluminum alloy structure. First, the fatigue test was designed and tested, and the results were analyzed by S-N curve, detail fatigue rating（DFR） and fracture location. Then, the finite element modeling and simulation are used to explain the experimental phenomena, and the mechanism of the interference fit to the fatigue gain is studied. Finally, the comprehensive detail fatigue rating results and the finite element simulation results are obtained, which are the standard recommended values of the high lock bolt assembly,and verified existing installation specifications, ensure the assembly quality of a certain type of aircraft.

Experimental and finite element research was conducted on the bolted interference fit of a single-lap laminated structure to reveal the damage propagation mechanism and strength change law. A typical single-lap statically loading experiment was performed, and a finite element damage prediction model was built based on intralaminar progress damage theory. The model was programmed with a user subroutine and an interlaminar cohesive zone method. The deformation and damage propagation of the specimen were analyzed, and the failure mechanism of intralaminar and interlaminar damage during loading was discussed. The effect of secondary bending moment on load translation and damage distribution was revealed. The experimental and simulated load-displacement curves were compared to validate the developed model's reliability, and the ultimate bearing strengths under different fit percentages were predicted. An optimal percentage was also recommended. [ABSTRACT FROM AUTHOR]

Monolithic U-type armature is one of the most important armatures in electromagnetic railgun. First, based on the traditional U-shaped armature, this article proposes a new structural design of the armature with interference at both ends. In addition, based on the calculation results of the interference fit module, a railgun multiphysical field coupling model is established. Second, through the interference fit module, the armature’s equivalent stress and a series of contact characteristics variables of the new armature with different structural parameters are calculated’C and the variation laws of the initial mechanical properties with different structural parameters are acquired. Finally, according to the current transport requirement of 200 kA, short-arm armature 1 and long-arm armature 2 are designed according to the traditional U-shaped armature structure design scheme, and the new armature 3 is designed according to the novel armature structure design scheme. Through the multiphysical field coupling model, the influence of the temperature and thermal stress on the launching performance of the three armatures is obtained. The calculation results show that the thermal stress and temperature will cause a sharp increase in the plastic volume and melting volume of the three armatures and eventually reduce the mechanical properties of the armatures. In addition, thermal stress will cause the contact position of the traditional armatures to move forward, affecting the stability of electromagnetic launching. However, the new armature can always maintain the contact between both ends of the tail and the rail, greatly reducing the influence of thermal stress on the armature launching performance. [ABSTRACT FROM AUTHOR]

The revolving armature can effectively improve the firing accuracy of the railgun, which rotates at high speed under the action of electromagnetic force during the movement in the bore. However, the research on the influence of the armature structural parameters on the startup contact state between the armature and the rail is rarely involved. In this article, for a 15-mm caliber railgun, the finite-element calculation model of the revolving armature assembly process of interference is established, and the interference fit of the traditional revolving armature with different structural parameters such as crack length C_L and width C_w, interference amount $d_{1}$ , tail thickness $t$ , and length $L_{1}$ is calculated, and the influence law of the structural parameters of the rotating armature on the initial contact states–contact area, contact force, maximum equivalent stress, and plastic volume is obtained. Second, on the basis of the traditional revolving armature, an armature structure with interference at both ends leading edge and trailing edge is proposed, and the influence law of interference at the leading edge and the middle turning position on the contact ratio at both ends of the new armature is obtained. Finally, the startup contact states of the new armature, the traditional long-arm armature (tail length 18 mm), and the short-arm armature (tail length 14 mm) are compared. The results show that the new armature can significantly reduce the equivalent stress and plastic volume of the armature. [ABSTRACT FROM AUTHOR]

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Developing a method for disassembly damage evaluation is of great significance for the key components in maintenance and remanufacturing. Disassembly of the interference fit joint between the shaft and impeller, which could inevitably bring damages to the parts’ surface, was investigated. The ferromagnetic materials FV520B (impeller) and 40CrNiMo7 (shaft) were used in the disassembly experiments. Experiments showed that different damage degrees appeared on the disassembled interface as a result of single sliding friction under different loads. The stress concentration and plastic deformation stimulated changes in magnetic domains, which led to the distortion of surface spontaneous magnetic field and the induction of metal magnetic memory (MMM) signals. The tangential components of MMM signals had peak-trough features with zero-crossing points, and the normal components showed peak features. The visible features of the distorted MMM signals could locate the position of the defects. The average damage depth Sa, peak-trough difference Wpp and peak area S had been proposed as characteristic values. The linear relationship between Sa and Wpp, Sa and S was further obtained, respectively. It indicated that the MMM technique was capable of quantitatively evaluating the disassembly damage of ferromagnetic parts, which also provided a reference for the remanufacturability assessment and the selection of repairing processes in remanufacturing engineering. [ABSTRACT FROM AUTHOR]

• Although there are many studies on fretting wear at present, they are limited to phenomena and mechanisms. Their calculation is very complex and not suitable for engineering design. To solve this engineering problem, this article firstly proposes a calculation method for the fretting contact fatigue strength. This method has never been published. There is absolutely no plagiarism in this paper. • The calculation method for the fretting contact fatigue strength has never been published in any international literature. This is the first submission in your journal. • Previously published papers focused on strength failure, but not on micro motion. This time it's about the fretting contact fatigue strength calculation. Fretting wear and gear contact fatigue belong to adhesive wear. They have similar causes, failure mechanisms, and failure appearance. Drawing inspiration from the gear contact fatigue strength theory, this article creatively proposes a calculation method for the fretting contact fatigue strength. The safety factor of fretting fatigue is calculated to be 0.34. Due to the singularity of the contact point at the edge of the oil groove, the mesh size near this point needs to be sufficiently fine to 0.025 mm. The contact pressure at the edge contact point of the oil groove is calculated by finite element method (FEM) to be 1034 MPa, which is 6.8 times the Lame theoretical value of 152 MPa. The stress concentration is very severe. The fretting contact fatigue strength at the edge of the oil groove is severely insufficient. The friction torque of the interference connection is calculated to be 3.1 times the overload torque of the motor. The fundamental cause of fretting wear is excessive interference and unreasonable design. [ABSTRACT FROM AUTHOR]

The residual stress generated from temperature changes and interference fit of rivet plays a significant role in the performance of C/SiC composites. To gain a thorough understanding of the residual stress evolution mechanisms and their influences on C/SiC composites, this work carries out comprehensive experimental research combined with simulation analyzes. The results of quasi-static tension tests present that as the environmental temperature rises from room temperature to 800 °C, the stiffness of structure increases a lot, while the strength of riveted joints significantly decreases. Furthermore, it is found that the microscopic failure modes are also changed. The cyclic unloading-reloading tests for calculating the residual stress quantitatively are conducted to explain the failure evolutions of structures. The obtained results reveal an important connection between the residual stress states and the microscopic failure modes of C/SiC composites. The environmental temperature and interference riveted joint both can affect stress state around the open hole, which are significant factors determining the damage modes and structural performance. In the process of C/SiC composites design, it is necessary to pay attention to the processing parameters of rivet interference fit to meet the performance optimization under service conditions. [Display omitted] [ABSTRACT FROM AUTHOR]

• Support stiffness effects on interface damage of the joints in the interference installation was investigated. • The mechanical response and interface damage behavior of the joints were evaluated and compared. • The effects of different support stiffness and lap type on the pressing-in load and interface damage were analyzed. • Damage formation mechanism and suppression strategy during installation were discussed. Interference installation-induced local interface damage becomes the source of bearing failure in service, which severely restricts the reliable application of composite interference-fit joints. To this end, support stiffness effects on interface damage behavior of thin-walled composite interference-fit joints in the installation was systematically investigated in this paper. The mechanical response and interface damage behavior of the joints were evaluated and compared by interference installation experiments and scanning electron microscopy (SEM). The effects of different support stiffness and lap type on the pressing-in load and interface damage were analyzed. Damage formation mechanism and suppression strategy during installation were discussed. Results show that the weaker the support stiffness is, the greater the bending degree caused by the bottom cantilever is, and the more severe the corresponding interface damage is. Increasing the number of laminated plates only increases the value of the pressing-in load, and has a very limited effect on the interface damage state. To reduce the interface damage of the joints in the installation, in addition to maintain the best interference-fit, keep a considerable value on the bottom support stiffness is also very necessary. [ABSTRACT FROM AUTHOR]

In this study the mechanical behaviors of shaft and hub were investigated by using the experimental tests by measuring the required axial load during coupling and decoupling in interference fitting. The surface roughness of the shaft and hub thickness effects on the mechanical property of interference was studied. All tests were performed for constant interference fit classes for three different surface roughness of the shaft without changing the inner surface roughness of the hub. Also four different outer diameters of hubs with keeping constant surface roughness of the inner diameter of hub studied, thus 21 samples of interference studied. The analysis of variance reveals in this study is that the best interference tightens condition is achieved at fine surfaces, the results also show that the hub thickness effect and increases the stresses are usually generated immediately and reach maximum value in the inner site of hub after the assembly completed. Finite element model of shaft and hub was established, and the equivalent stress and contact stress for different hub thickness were computed after interference coupling, diameters in the thin hubs increase when coupling complete which reduces the interference between the shaft and hub.

With respect to the design calculation of the interference fit construction of the output shaft of cooling water pumps used in a nuclear power plant,the design calculation and checking are carried out by using standard formulas and numerical methods specified in the National Standards for limit and interference fit.The contact pressures at the maximum and minimum interference are obtained respectively,and the assessment of the reliability of transmitted torque and material is conducted,then the minimum temperature required for interference assembly is calculated,the protection for the safe and reliable operation of pump is provided.