Interference Fit Research Articles

Intraoperative Efficiency in Contemporary Total Shoulder Arthroplasty: Is Manual Pressure During Cement Curing Still Necessary With Interference Fit Pegged Glenoids?

No previous data have demonstrated the effect of manual pressure during cement curing on interference-fit glenoid implant fixation in total shoulder arthroplasty. In this study, we examined cement mantle characteristics and implant seating using two different methods of securing an interference-fit glenoid implant with peripheral cemented pegs: a manual pressure technique versus a pressureless technique. Sixteen cadaveric scapulae were harvested, and their glenoids were prepared for component insertion. Glenoids with an interference-fit central peg were cemented into the peripheral holes and fully seated. Two techniques were employed during cement curing: (1) a manual pressure technique (8 glenoids), which used a static 70 N load application to each implant for 10 minutes; and (2) a pressureless technique (8 glenoids), which used no pressure application, and the implant was left to set without intervention. Each glenoid was subsequently imaged using microcomputed tomography and analyzed for differences in cement mantle characteristics and implant seating. The mean area of cement penetration for the manual pressure technique was not statistically different from the pressureless group (P = .26, valid N = 288). The average implant incongruity after final seating in the manual pressure group was 0.63 mm, compared with 1.0 mm in the pressureless group. A linear mixed effects model with a Kenward-Roger correction was used to compare the two groups, and no significant difference was found (Mdiff = -0.386, 95% confidence interval: -0.978 to 0.206; P = 0.17). Manual pressure of the glenoid component during cement curing yielded no difference in the cement mantle area or final implant seating incongruity compared with a pressureless technique. This knowledge could potentially benefit both the surgeon and the patient by increasing the efficiency in total shoulder arthroplasty surgery.

Combined effects of seawater ageing and fatigue loading on the bearing performance and failure mechanism of CFRP/CFRP single-lap bolted joints

The aim of this paper is to investigate the combined effects of seawater ageing and fatigue loading on the bearing performance and failure mechanism of CFRP/CFRP single-lap bolted joints. The bolted joints with an interference fit size of 1.15% were prepared and then immersed in artificial seawater (50 °C-3.5% NaCl solution) for 7 months. After that, fatigue loads were further applied to the unaged and aged joints. Finally, single-lap bearing tests were carried out to evaluate the bearing performance of seawater aged and fatigue load treated joints. Scanning electron microscope (SEM) was used to analyze bearing failure morphology. The experimental results showed that the ultimate bearing load of joints suffered the single effect of seawater ageing decreased exponentially with the increase of ageing time, while the joints suffered the combined effect of seawater ageing and fatigue loading decreased linearly. Moreover, compared with the single effect joints, the bearing capacity of combined effect joints showed a significant improvement. Furthermore, the failure mechanism of single effect joints was mainly the shearing fracture in bearing zones, and such shear angle increased with ageing time. However, the failure mechanism of combined effect joints was changed to be delamination in bearing zones.

Fretting fatigue and wear of mechanical joints: Literature study

Most mechanical connections are in one way or another exposed to some form of tear, wear, corrosion and fatigue, and likely to fail over time. If the contacting surfaces in a connection are exposed to tangential loading due to vibrations, small amplitude displacements called fretting can be induced at the surface, and might result in crack nucleation and possible propagation. The review and analysis reported herein are based on review of a wide range of studies reported in the literature during the last 25 years, which look into earlier studies around fretting fatigue in interference fit connections. In addition, a new method on how to obtain an interference fit is being mentioned as a possible way of increasing the joints fretting fatigue life. Previous investigations show clearly positive effects of finding and operating with the correct combinations of interference fit levels, palliative treatments and material choices to increase the fretting fatigue life.

Design of Armature Interference Structure of New Quadrupole Track Electromagnetic Launcher

How to provide pre-tightening force for armature and how to achieve interference fit between armature and track are the basic and key difficult problems in the research process of electromagnetic track launcher, which directly affect the contact characteristics between armature and track, and have important research significance. Firstly, according to the armature arm structure of C-type armature of railgun, the interference structure of armature of new quadrupole track electromagnetic launcher is designed. Then, in the simulation process, two kinds of interference structures are simulated and analyzed by the loading assembly method. Finally, the final structure of armature interference is determined based on the four performance indicators of stress, pressure contact efficiency, stress and pressure distribution uniformity to quantify the contact characteristics. The results show that scheme 2 is more suitable for armature of new quadrupole track electromagnetic launcher, and has the best performance index when the interference is 0.6 mm.

Multiobjective Intelligent Cooperative Design for the Multilayer Interference Fit

Interference fit has extensively been applied in different mechanical fields due to its advantages such as compactness and high rigidity. With the actual needs of engineering, the multilayer interference fit has also been widely used. It is significant for the design and manufacture of multilayer interference fit to consider stress concentration problem and achieve multiobjective and multivariable collaborative optimization in the optimization algorithm. To achieve this goal, the mechanical model and reliability mathematical model of the multilayer interference fit are established. Giving an evaluation method of reliability, the recommended range of interference amount is obtained. Considering the lightweight design and stress concentration problems, a multiobjective intelligent cooperative design (MOICD) method for the multilayer interference fit is proposed, and multiparameter analysis is done. Taking the typical wind turbine’s shrink disk of three-layer interference fit structure as an application example, the key design parameters of the shrink disk are determined, and its sample data are obtained using the orthogonal experimental method. Considering yield strength, torque, and mass, the approximate mathematical model of response surface using the Kriging algorithm is given. Nondominated sorting genetic algorithm-II (NSGA-II) is selected as the optimal algorithm to realize MOICD of the shrink disk. Numerical analysis and analytical calculation proved that the optimization index of the MOICD method is improved compared with the traditional method. The sample is tested on a specific test bench, and the test results meet the design requirements, which verifies the feasibility of MOICD.

Ultra-light release device integrated with screen-printed heaters for CubeSat’s deployable solar arrays

Deployable solar arrays can improve the potential utilization of CubeSats by generating sustainable energy. This paper presents an ultra-light release device integrated with screen-printed heaters to latch and release CubeSat’s solar arrays in the sequence of structure and material design, fabrication, and experimental verification. Finite element analysis of interference fit gives the locking force and maximum Von Mises stress variation with the interference and thickness, which provides the selection basis for geometrical parameters of the release device. Tensile and fracture toughness tests have been conducted to verify improved toughness for spandex fiber reinforced shape memory polymer composites (SMPCs). And the fine denier fiber shows a better toughness improvement performance. DMA tests have been performed to give the temperature sensitivity of the materials. Besides, locking forces obtained from finite element analysis and experiments show good consistency. Moreover, recovery tests confirm the release device with good shape recovery properties and excellent adaptability to energizing conditions. Finally, experiments on a CubeSat prototype qualify the release device with good feasibility, reliable locking performance and satisfactory reusability. This work is expected to provide an effective miniaturized hold-release mechanism for deployable structures.

Design and Optimization of Halbach-Array PM Rotor for High-Speed Axial-Flux Permanent Magnet Machine With Ironless Stator

In this article, a high-speed Halbach-array permanent magnet (PM) rotor for ironless stator axial-flux permanent magnet (AFPM) machine is proposed and researched with consideration of the multiphysics constraints, including the electromagnetic characteristics, mechanical strength, and rotor dynamics. Considering the severity of attractive force between twin rotors, the complex repulsive force among PM segments of Halbach-array and centrifugal force, the new hybrid sleeve, and PM fixation method are proposed to improve the rotor mechanical strength. Then, the rotor stress is analyzed by numerical analysis and three-dimensional (3-D) finite-element analysis (FEA). Furtherly, the sleeve thickness and interference fit are optimized by 3-D FEA. The rotor dynamics and bearing arrangement are analyzed to validate the effectiveness of the high-speed Halbach-array PM rotor. A 50-kW, 9000 r/min ironless stator AFPM machine prototype with Halbach-array PM rotor is manufactured and tested. The measured results show that the output power is up to 53.8 kW at 9000 r/min. The feasibility of high-speed Halbach-array PM rotor and accuracy of analysis method are validated by both simulated and measured results.

Dependence of the primary stability of cementless acetabular cup implants on the biomechanical environment

Biomechanical phenomena occurring at the bone-implant interface during the press-fit insertion of acetabular cup implants are still poorly understood. This article presents a nonlinear geometrical two-dimensional axisymmetric finite element model aiming at describing the biomechanical behavior of the acetabular cup implant as a function of the bone Young's modulus Eb, the diametric interference fit (IF), and the friction coefficient µ. The numerical model was compared with experimental results obtained from an in vitro test, which allows to determine a reference configuration with the parameter set: μ* = 0.3, , and IF* = 1 mm for which the maximal contact pressure tN = 10.7 MPa was found to be localized at the peri-equatorial rim of the acetabular cavity. Parametric studies were carried out, showing that an optimal value of the pull-out force can be defined as a function of μ, Eb, and IF. For the reference configuration, the optimal pull-out force is obtained for μ = 0.6 (respectively, Eb = 0.35 GPa and IF = 1.4 mm). For relatively low value of µ (µ < 0.2), the optimal value of IF linearly increases as a function of µ independently of Eb, while for µ > 0.2, the optimal value of IF has a nonlinear dependence on µ and decreases as a function of Eb. The results can be used to help surgeons determine the optimal value of IF in a patient specific manner.

Automatic press-fit assembly of small precision interference fitting parts: armature of electro-hydraulic servo valve

PurposeThe purpose of this paper is to design an automatic press-fit instrument to realize precision assembly and connection quality assessment of a small interference fitting parts, armature.Design/methodology/approachIn this paper, an automatic press-fit instrument was developed for the technical problems of reliable clamping and positioning of the armature, automatic measurement and adjustment of the attitude and evaluation of the connection quality. To compensate for the installation error of the equipment, corresponding calibration method was proposed for each module of the instrument. Assembly strategies of axial displacement and perpendicularity were also proposed to ensure the assembly accuracy. A theoretical model was built to calculate the resistant force generated by the non-contact regions and then combined with the thick-walled cylinder theory to predict the press-fit curve.FindingsThe calibration method and assembly strategy proposed in this paper enable the press-fit instrument to achieve good alignment and assembly accuracy. A reasonable range of press-fit curve obtained from theoretical model can achieve the connection quality assessment.Practical implicationsThis instrument has been used in an armature assembly project. The practical results show that this instrument can assemble the armature components with complex structures automatically, accurately, in high-efficiency and in high quality.Originality/valueThis paper provides a technical method to improve the assembly quality of small precision interference fitting parts and provides certain methodological guidelines for precision peg-in-hole assembly.

Contact stress analysis of disc cutter peg-hole with interference fit

To study the relation of the interference fit between cutter body and cutter ring, a theoretical design of interference fit of the cutter peg-hole is carried out according to the theory of thick-walled cylinders. The finite element method is used to analyzed the mapping relationship between the contact stress of cutter ring and cutter body. Thermal expansion assembly of the cutter ring is simulated, and the temperature of the thermal expansion assembly of the cutter ring is determined. The result shows that the contact length between the cutter body and the cutter ring has little influence on the contact stress of the cutter ring, but with increasing contact length the stress concentration of the retaining ring will increase. The contact stress of the cutter ring is basically the same at the same amount of interference and temperature, but the contact stress of the ring decreases with increasing contact length at high temperature. When the contact length is the same, the contact stress and the radial force of the mating surface increase with increasing amount of interference. The reasonable temperature for thermal expansion assembly of the cutter ring is 160 °C.

Satisfactory postoperative alignment following retrograde SIGN Fin nailing for femoral shaft fractures

Purpose:In developing countries, long bone fractures following trauma are a significant contributor to morbidity, and operating room resources are often limited in these settings. The Surgical Implant Generation Network (SIGN) Fin nail may reduce the challenges of retrograde intramedullary nailing of femoral fractures without fluoroscopy. In contrast to the traditional SIGN nail placed in a retrograde fashion, the Fin nail does not require proximal interlocking screws. Instead, the nail achieves stability through an interference fit within the proximal femoral canal. The purpose of this study is to compare postoperative alignment in femoral shaft fractures treated with either a retrograde SIGN Fin nail or a standard retrograde SIGN nail.Method:Using the SIGN online surgical database, we identified all femoral shaft fractures treated with a retrograde SIGN Fin nail at 2 African hospitals. Two examiners independently classified fracture patterns using the Arbeitsgemeinschaft für Osteosynthesefragen/Orthopaedic Trauma Association (AO/OTA) classification system. Using an on-screen protractor tool, postoperative coronal and sagittal plane alignment were measured and recorded as deviation from anatomic alignment (DFAA), with units in degrees. Available patient demographics and surgical details were also recorded. Fin nail cases were matched in a 1:1 ratio to retrograde standard SIGN nail cases based on AO/OTA fracture type.Results:Twenty-eight retrograde Fin nail cases were identified, and 28 matched retrograde SIGN nail cases were selected. The Fin nail and retrograde SIGN nail groups were well matched in terms of demographics, AO/OTA fracture type, and surgical characteristics. There was no significant difference in postoperative coronal or sagittal plane alignment between the groups. There were no cases in either group of average postoperative malalignment >5° in any plane.Conclusion:The SIGN Fin nail appears to achieve satisfactory radiographic alignment without the need for proximal interlocking screws, making it an attractive implant for retrograde femoral shaft fracture fixation in resource-limited settings. Further research is required to validate these findings and determine long-term Fin nail clinical outcomes.

Improving precision in the prediction of laser texturing and surface interference of 316L assessed by neural network and adaptive neuro-fuzzy inference models

Laser-based surface texturing provides highly controlled interference fit between two parts. In this work, artificial intelligence-based models were used to predict the surface properties of laser processed stainless steel 316 samples. Artificial neural network (ANN) and adaptive neuro-fuzzy inference system (ANFIS) were used to predict the characteristics of laser surface texturing. The models based on feedforward neural network (FFNN) were developed to examine the effect of the laser process parameters for surface texturing on 316L cylindrical pins. The accuracy of the models was measured by calculating the root mean square error and mean absolute error. The reliability of the ANFIS and FFNN models for the output prediction of the laser surface texturing (LST) system were investigated by using the data measured from experiments based on a 3^3 factorial design, with main processing parameters set as laser power, pulse repetition frequency, and percentage of laser spot overlap. The relative assessment of the models was performed by comparing percentage error prediction. Finally, the impact of input data was examined using predicted response surface plots. Results showed that ANFIS prediction was 48% more accurate compared with that provided by the FFNN model.

Effects of Prestressing of the Ring Gear in Interference Fit on Flexural Fatigue Strength of Tooth Root

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.

Fatigue response of electromagnetic riveted joints with different rivet dies subjected to pull-out loading

Electromagnetic riveting (EMR) as a green manufacturing and efficient process has extensive application prospect in engineering fields. In this study, the fatigue properties of electromagnetic riveted joints with different rivet dies under pull-out loading were studied. The results showed that rivet dies had a significant effect on the pull-out fatigue performance. The pull-out fatigue life of the electromagnetic riveted joints with special dies was higher than that with the flat die. The reason was that the special rivet dies restricted the radial flow of the material in driven head. More material flowed into the riveted hole and rivet shaft became larger. The joints were reinforced by larger interference fit. Particularly, the joints with 80° rivet die had the best pull-out fatigue properties due to more uniform and moderate interference fit. Fracture analysis showed that there were two typical failure modes for the joints under pull-out loading: rivet manufactured head and upper sheet fracture. Due to the effect of cyclic impact and fretting wear damage, the joints with a flat die at high stress levels (194.8 MPa and 173.2 MPa) failed in rivet manufactured head, while the joints with special dies at all stress levels and with a flat die at low stress levels (151.5 MPa and 129.87 MPa) failed in upper sheet.

Characterization of the residual stresses introduced by a new joining method in diamond and tungsten carbide composites

In this work, a co-sintering method was used to attach diamond to cemented carbide composites. The joining method consists of sintering a green part (ring) of cemented carbide (CC) around a thermally stable diamond composite (TSDC) part (plug) to radially contain it. During the sintering step, the green body shrinks to a controlled level and therefore forms interference fit between the two parts (mismatch between the inner diameter (ID) of the CC ring and the outer diameter (OD) of the TSDC cylinder). The residual stresses induced by this process as well as the bond strength between the CC and the TSDC parts were quantitatively evaluated. It is shown that the interface pressure between the two parts, and the level of residual stresses, increased with increase in the designed interference fit, as well as with the increase of the ID/OD ratios of the CC ring.For the chosen material combination (cemented carbide ring comprised 90 vol% WC and 10 vol% Co with medium coarse WC grains; diamond composite plug comprised 84 vol% diamond and 16 vol% SiC), the values of the hoop stresses at the interface in the CC ring measured by neutron diffraction was determined to be between 150 MPa and 550 MPa, depending on the ID/OD ratio. It was also found that for a given ID/OD ratio, the increase of the designed interference fit had little effect on that attained due to the plastic deformation of the cemented carbide material at the interface during the sintering (dynamic) process. A mechanical bond around 60 MPa was nevertheless achieved.

Numerical Investigations on the Sealing Performance of a Reciprocating Seal Based on the Inverse Lubrication Method

The work presented in this paper describes a new approach to calculate the film profile, friction, and fluid transport of a reciprocating U-cup seal used in a hydraulic piston pump. An innovative partial lubrication model of the seal is developed, which connects the inverse hydrodynamic lubrication method and Greenwood–Williamson asperity contact model. Finite element models (FEM) were established to simulate deformation behavior under-mounted and pressurized process using finite element code ansys. Based on the finite element simulations, corresponding numerical calculations have been made using the matlab with the inverse hydrodynamic lubrication and asperity contact theories. The accuracy of these models was validated against existing experimental data to ensure that they can predict the sealing performance sufficiently. The effects of the operating parameters as well as the magnitude of interference on the sealing performance in terms of friction, fluid transport, and film thickness were discussed. The results of the simulation indicate that the interference fit, sealed pressure, and rod velocity play significant roles to improve the wear and seizure resistance capability that is critical to the service life of the seal.

The field of tensions of a rotating anisotropic disc of a variable thickness loaded with undistracted forces on the outer contour

The work gives a solution of the plane elasticity problem for rotating polar-orthotropic annular disks of a variable thickness. The disk is loaded with a system of equal focused forces on the outer contour applied evenly along the rim and symmetric concerning the diameter. The disk is seated with an interference fit on the flexible shaft so that a constant contact pressure acts on the interior contour. The stresses and deformations arising in such a rotating anisotropic annular disk will be non-axisymmetric. A conclusion of a fourth-order partial differential equation for the effort function is drawn. Its general solution is searched out in the form of a Fourier series of cosines with even numbers. As a result, an infinite system of ordinary differential equations is solved for the coefficients of the series. These differential equations correspond to the linear Volterra integral equations of the 2 nd kind, which are solved using resolvents. Constants of integration are determined from the border conditions. Expressions for the stress components are written through the effort function by the well-known formulas. We find the components of the displacement vector in the disk by the integration of the Hooke’s law equations for the polar-orthotropic plate. We calculate the deformation components in a ring anisotropic disk by Cauchy differential relations if we know the displacements. The solved formulas for stresses, deformations and displacements completely describe the stress-deformed state in a rotating polar-orthotropic disc of variable thickness with a system of focused forces on the outer contour. The results of the work can be used in the design of working disks of turbomachines and turbo compressors, as well as rotors of centrifugal stands.

АНАЛИЗ ОСТАТОЧНЫХ НАПРЯЖЕНИЙ ПРИ ПРИМЕНЕНИИ КОНСТРУКТИВНО-ТЕХНОЛОГИЧЕСКИХ МЕТОДОВ ПОВЫШЕНИЯ ДОЛГОВЕЧНОСТИ. СООБЩЕНИЕ 1. СВОБОДНОЕ ОТВЕРСТИЕ

Increasing the fatigue life of elements of aircraft structures by methods based on local plastic deformation of the material in the hole zone directly depends on the magnitude and sign of the residual stresses. This paper presents the results of the study of residual stresses, which are formed when using constructive-technological methods to improve the durability of elements of aircraft structures with a free hole. The processes of cold expansion and barrier compression of the material in the area of the hole are considered. The studies were performed using the finite element method for two aluminum alloys D16AT and V95pchT2, which are widely used in the domestic aircraft industry. Material properties are given in the form of monotonous strain diagrams obtained by tensile testing of standard samples. The contact problem was solved in a physically nonlinear formulation, taking into account the friction between the tool and the structural element. The nonlinear behavior of the material is modeled using a multilinear model with kinematic hardening, taking into account the Bauschinger effect. Characteristics of the stress-strain state arising in the structure after the completion of the process of refining and barrier compression have been obtained. Equivalent stresses calculated according to the energy theory of strength were analyzed as residual stresses. In this case, the sign of stress is taken to be equal to the sign of the largest in magnitude principal stress. In the study of the process of cold expansion, a variable parameter was interference fit. The dependence of the residual stress in the hole on the magnitude of the interference fit is obtained. In the case of barrier compression, the variable parameters were the geometry of the tool being introduced (width, grip angle), the thickness of the structural element and depth of implementation. The dependences of the change in residual stresses on the parameters considered are constructed. It is shown that such parameters can be selected, at which the effect of compression will be most significant. But this will increase the effort required to complete this process.

Strength of the shaft/hub joint using a finite element model

This article describes the effect of the roughness size on the axial slip strength between the parts of shaft/hub joints with interference fit. The surface roughness was obtained from a turning process with different finishes (fine, medium and rough). A finite element modeling was developed, which uses a normal contact stiffness equivalent to the size of the surface roughness between the joint pieces to represent the real contact. In order to validate the numerical model, theoretical results of contactpressure and extraction force of the shaft/hub joint with smooth elements were compared with the corresponding numerical results obtained. The numerical results from studies that considered the size of the surface roughness showed that the axial load capacity of the joint decreased with larger roughness.

Post-installed shear connectors: Push-out tests of coiled spring pins vs. headed studs

Steadily increasing traffic volumes and traffic loads lead to a continuously growing demand for bridge rehabilitation, strengthening and replacement projects. For existing steel girder bridges with non-composite concrete decks, the traffic load capacity can often be increased significantly if composite action can be created afterwards. Different kinds of shear connectors are more or less suitable for post-installation. Coiled spring pins are one type of interference fit connector that can be installed from below the bridge deck during traffic, in order to minimize the impact on road users. This paper describes an experimental study on the static capacity and stiffness of coiled spring pins used as shear connectors at steel-concrete interfaces. Six push-out test series are presented, with a total of 28 tests, together with an alternative type of test set-up. The results show that the failure of the coiled spring pins is very ductile and that the load capacity is predictable and sufficient for a cost-effective application. The tests also indicate a significantly lower stiffness of the connectors in comparison to welded headed studs of similar dimensions, which might be of great importance if an existing shear connection is strengthened.