Press-fit Joint Research Articles

Study of the Press Fit Bearing‐Shaft Joint Dimensional Parameters by Analytical and Numerical Approach

The study of press fit bearing‐shaft joint dimensional parameters by means of analytical and numerical calculations in order to identify those parameters of the press fit joints which significantly influence the life of the bearings fitted by pressing is dealt in this paper. The mounting and conditions of fit joint are the significant factors affecting the operability and life of the bearings and consequently that of rotating machines and the whole technical units. The aim of the analysis and study is to determine the tangential and radial stress, the radial displacement, and the influence of the shape features and the size of the interference on the change of the radii in the press fit bearing‐shaft joint, in particular, the ball bearings of 6014 2RSR C3 type. Moreover, on the basis of obtained results, the paper discusses the impact of shaft dimensional and geometrical accuracy on the bearing lifetime.

The influence of a CrN+a-C:H:W coating on the development of fretting wear in a model of a wheel–axle press-fit joint on a wheel set of a railway vehicle

The influence of a CrN+a-C:H:W coating on the development of fretting wear in a model of a wheel–axle press-fit joint on a wheel set of a railway vehicle

Early Term Functional Results of the Three-Component Total Arthroplasty in the Treatment of Hallux Rigidus

Aim: Hallux rigidus is a disease characterized by degeneration of the first metatarsophalangeal (MTF-1) joint. The choice of arthroplasty instead of arthrodesis in the surgical treatment of advanced hallux rigidus is still controversial. In this study, we aimed to report the early treatment results of a number of patients who had advanced hallux rigidus and underwent new-generation three-component press-fit total joint arthroplasty. Materials and Methods: The patients were evaluated in terms of degrees of MTF-1 joint dorsiflexion, plantar flexion, and total joint range of motion (ROM), scores of AOFAS, VAS, SF-12 PCS, and satisfaction survey results. The preoperative and postoperative values were analyzed statistically. Radiologically, anteroposterior (AP) and lateral radiographs were taken and examined for loosening, wear, and alignment. Results: Nineteen joints (14 female, 5 male) of 17 patients were included in the study. The mean age was 59 (49–67) years. The mean patient follow-up was 15 (12–22) months. The mean dorsiflexion degree was 12.7° (range 2.1°–22.1°) preoperatively and 30.1° (11.6°–47.3°) postoperatively. The mean plantar flexion degree was 16° (7.8°–24.2°) preoperatively and 9.2° (2.3°–16.5°) postoperatively. The total range of motion (ROM) of the MTF-1 joint improved from a preoperative 28.4° to a postoperative 39.4°. The mean postoperative AOFAS, VAS, and SF-12 PCS scores were calculated as 85.3 (57–96), 1.3 (0–5), and 57.7 (53.7–59.9), respectively. The increase in the patients’ AOFAS and SF-12 PCS scores and the decrease in the VAS scores were found to be statistically significant. Discussion and Conclusion: Advanced MTF-1 joint osteoarthritis is a disease that causes severe pain and loss of motion. The method for a standard surgical treatment is still controversial. It has been reported in the literature that satisfactory results have been achieved in applications of three-component cementless press-fit total prostheses, in contrast to older prosthetic applications that cause serious complications. The pain relief and the increase in AOFAS scores are considered the most successful aspects of the treatment. Based on the information obtained from this study, we think that application of new-generation three-component press-fit total prostheses is an effective method in the treatment of advanced hallux rigidus, and that the early results are satisfactory when it has been applied to appropriate patients.

Assessment of the possibility of the application of a CrN+OX multi-layer coating to mitigate the development of fretting wear in a press-fit joint

Press-fit joints should be durable and reliable, and this pertains in particular to joints operating in severe conditions or those directly influencing safety, such as rail vehicle wheel sets. Therefore, attempts to eliminate factors enhancing the development of wear should be made. The application of PVD coatings may be a way of improving joint durability.In this article, an assessment was undertaken of the possibility of the application of PVD coatings to mitigate the development of fretting wear in press-fit joints. Wear tests were conducted on the example of a sleeve/shaft connection operating in rotational bending conditions, and the negative allowance of 0.02mm was taken. Test samples were divided into two groups. The first comprised samples without coating, and in the second a CrN+OX multi-layer coating was applied onto shafts. The analysis of fretting wear consisted in comparing wear images. Joint dimensions and operation conditions were chosen in such a way that operation conditions of rail vehicle wheel sets could be simulated.As part of laboratory tests, the macroscopic and microscopic observations of the shaft top layer wear and the microscopic observations of the sleeve/shaft joint surface were conducted. Macroscopic observations demonstrated the occurrence of fretting wear at shaft surfaces in both sample groups under testing, however, the range of wear occurring in samples with the CrN+OX coating was much smaller. The microscopic observations of shaft surfaces revealed a similar image of fretting in both sample groups under testing, such an image consisting of wear in the form of material build-up, microgaps, micropits and microcracks. The chemical analysis of wear products demonstrated their plastic deformation and oxidation. Scientific research indicates that adhesion is the process initiating the development of fretting wear; in these tests an attempt was made to eliminate adhesion. The application of the coatings under testing produced the expected result. The appropriate hardness of the shaft top layer with coatings caused the mitigation of adhesion thus significantly reducing the development of fretting wear.

Ultrasonic Assembly of Press-Fit Joints

The behavior of press-fit joints under the action of ultrasound is studied. The influence of ultrasound and the tightness of the joint on the quality of assembly is considered.

Methods for Research of Joints with Composite Materials

В данной научной статье проведен анализ различных методов неразрушающего контроля для обоснования их применения в качестве инструмента исследования прочности клеевых соединений с композиционными материалами. Приведены прочностные свойства соединений с натягом, в зону сопряжения которых введены компаунды, с плохо изученными адгезионными свойствами, проведены серии контрольных экспериментов на основе неразрушающих и разрушающих методов, дана оценка напряженному состоянию сопряжения и прилегающих к ней слоев. Необходимые свойства клеевого соединения зависят от множества факторов, одним из которых является взаимодействие с особыми участками склеиваемых поверхностей; другой - среднее значение контактного давления, которое требуется для максимального прилегания поверхностей. Независимо от конструктивных параметров (соединение с зазором или соединение с натягом) способ сборки обеспечивает гарантированное заполнение пространства между сопрягаемыми деталями композиционным материалом, подаваемым в зону сопряжения различными способами. Для обеспечения дальнейшего применения соединений необходимо установить взаимосвязь прочности, определенной экспериментально, и показаний приборов при неразрушающем методе контроля. Такой подход позволит расширить область применения как клеевых соединений, так и соединений с прослойкой из наноструктурированного компаунда. Сборка соединений может осуществляться при относительном смещении собираемых деталей в условиях жидкостного трения, обеспеченного материалом клеевого компаунда. Проведен выбор наиболее оптимального, с точки зрения практики, метода контроля клеевых соединений с натягом с композиционной прослойкой. Показано преимущество метода введения сегнетоэлектрических добавок в клеевой слой для оценки прочностных характеристик клеевых соединений при использовании акустоэлектромагнитного метода.

Investigation into the causes of fracture in railway freight car axle

Railway axles are vital parts of railway. Their failure in the form of dynamic fracture is commonly of disastrous outcomes for railway vehicles. Accordingly, railway axles are designed to be highly reliable, while the maintenance system requires regular inspection in terms of crack initiation. However, due to complex exploitation conditions, complex stress state and multiple stress concentration, railway axles often experience fatigue failures. This occurrence has been studied in a large number of papers. This paper too sheds light on the causes of fracture occurrence in the axle of railway freight car for coal transport in a thermal power plant. Detailed analyses were conducted on the axle fracture surface and mechanical properties. Also, microstructure of the axle material, as well as on exploitation conditions and stress state was examined. Calculations indicated that, apart from working load impact, the influence of press fit joints, especially of the one between the labyrinth seal and the axle is of crucial importance for the analysis of railway axle stress state. The entire numerical–experimental analysis has shown that the considered axle failure was caused by inadequate maintenance, insufficient axle strength and adverse stress state in the railway axle critical cross-sections.

Study of the interference contribution on the performance of an adhesive bonded press-fitted cylindrical joint

The adhesive bonding technology can be used in combination with other traditional joining methods, such as mechanical fastening techniques (e.g. rivets or bolts) or welding techniques, generating a hybrid joint. Hybrid adhesive joints are designed to exploit the advantages of the different techniques and, if possible, overcome their drawbacks. This study focuses on the interference fitted/adhesive bonded joining technique. This method consists in two cylindrical components coupled together by inserting one into the other, after having placed an adhesive on the mating surfaces. This hybrid joint, generally realized by exploiting acrylic anaerobic systems, has been studied to evaluate the interaction between the tensile field of the components (at the interference level) and the adhesive strength under both static and dynamic loading conditions. Notwithstanding this, the contributions of the adhesive and the interference on the performance of the final joint are still not completely clear. The aim of this research is then to further study the factors affecting the resistance of this hybrid joint. Hub-shaft samples, joined by means of a press fit, were tested under an axial push out load. Hybrid joints were compared to both adhesive joints in clearance conditions and interference joints. In particular, different levels of interference were analyzed in order to clarify the role played by the tensile field between the hub and the shaft, and the influence of the friction effects between them. Numerical simulations were also employed to support the experimental data in the evaluation of the behavior of the adhesive and its relation with all the phenomena influencing the hybrid system. It was found that tribological phenomena played an important role in governing the mechanical behavior of the unbonded samples, while they can be considered negligible in presence of the adhesive. The correlation between bonded and unbonded press-fitted joints was investigated pointing out that the maximum strength of the hybrid joint is mainly related to the resistance of the epoxy adhesive.

The impact of fin profile and interface condition on performance characteristics of heat sinks

Thermal management of electronic products relies mainly on the effective dissipation of heat. Heat sinks (containing multiple extended surfaces or fin array) are commonly used for heat dissipation network. The performance of an individual fin depends on its geometry, material properties and operating environment (i.e. free or forced convection). In the first part of this paper, the four most commonly used fin profiles are studied for pin, longitudinal and annular fins using non-dimensional finite element formulation. In the second part, the performance of different thermal interfaces is studied for polymer and metallic fins. Polymer composite materials result in significant increase in the performance of a fin; however manufacturing can be a constraint to construct an effective heat sink due to interface conditions at the fin and base plate junction. It is found that the joint at fin base plate has considerable stress effect in the heat sink system. The press fit joint must have high contact pressure to maintain an appropriate thermal contact conductance (TCC) in order to have thermal performance comparable to an adhesive joint, but the two joints have different state of thermal and contact stresses.

Vibration of Conducting Two-Layer Sandwich Homogeneous Elastic Beams in Transverse Magnetic Fields

AbstractA theory governing the flexural vibration of a conducting two-layer sandwich homogeneous elastic beam in a transverse magnetic field is presented. The physics driving this problem derives from an energy dissipation mechanism through press-fit joints in structural laminates. Recent advances made in the mechanics of sandwich-layered structures have shown that by simulating an environment of nonuniform interface pressure, structural vibration can be attenuated significantly. Equations of mathematical physics governing the stresses and the structural vibration are derived via a laminated beam theory employing the Newtonian form of Cauchy’s stress equations. By restricting mathematical analysis to the case of cantilever architecture, a closed-form polynomial expression is derived for the system response. In particular, the effects of magnetoelasticity, material conductivity, and interfacial pressure gradient on the response characteristics are demonstrated for design analysis and engineering applicatio...

On Vibration and Noise Dissipation in Ship and FPSO Structures with Smart Systems

Ships and floating structure production systems are widely deployed for deep and ultradeep waters operation. Active vibration reduction and noise control in such structures can significantly improve their hydrodynamic performance and stability during navigation, exploration, and exploitation activities. One way to minimise or reduce the transmission of vibration in these moving offshore structures is to exploit the mechanism of interfacial slip in press fit joints or layered structural laminates in their internal hull configurations to dissipate vibration energy. In this paper, slip damping with heterogeneous sandwich composite viscoelastic beam-plate smart systems as a model for dissipation of vibration and active noise control mechanism in ship and floating structures is investigated. For this problem, a boundary value partial differential equation is formulated for the case of linear and nonlinear hydrodynamic wave loadings. In particular, the effect of pressure distribution variation at the interface of the layered smart system on the energy dissipation, logarithmic damping decrement, and spatial transfer function is analyzed and presented for design application and selection of appropriate stabilizers.

How to improve static and fatigue strength in press-fitted joints using anaerobic adhesive

This study is focused on the static and fatigue strength of interference-fitted connections supplemented with anaerobic adhesive ( hybrid joints). Through axial release tests, it is demonstrated that the addition of the adhesive always improves the performance of the joint. The main achievable benefits can be summarized in (a) the possibility of increasing the load transfer capability with the same joint geometry and (b) reducing both the weight and the stress field of the joint with the same load transfer capability. The objective of the study is to provide some relevant information on the static and fatigue strength properties in case of both steel–aluminium components ( mixed hybrid joints) and steel–steel components ( steel hybrid joints). Furthermore, the authors provide some design formulae useful to predict the releasing force (the strength of the joints) both under static and dynamic conditions. Relevant improvements can be obtained using the anaerobic adhesive in terms of releasing force, which increases at least of 40 per cent. The proposed results derive from a collection of 200 experimental tests performed by the authors on a high-strength, single-component adhesive, which cures anaerobically (LOCTITE 648®).

Recommendations for the estimation of the strength of the railway wheel set press fit joint

Although press fit joints are very important in railway engineering, few authors have investigated the strength of press fit joints in terms of their application in railway vehicles. This study analyses the tribological parameters that influence the strength of press fit joints, especially the contact pressure and the static friction coefficient. This research was targeted towards the control of the friction coefficient value to obtain the required strength of a press fit joint in conditions close to the minimum contact pressure that results in less prestressed press fit joints. To estimate press fit joint strength, this study examines the use of minimum and maximum values of the friction coefficient as recommended in the literature considering wide tribological conditions, as well as the experimentally determined friction coefficient values for specific tribological conditions. The study also points out the discrepancy between current railway standards and engineering practice considering the inspection of wheel set press fit joint strength.

Torque Transmission Characteristics of the Press Fit Joint Between the Aluminum Shaft and Steel Ring with Small Teeth

Hybrid or aluminum tube structure requires reliable joining of the shaft to other components such as steel yoke and universal joint, which is often the most difficult task. Therefore, a reliable joining method between the aluminum tube and the steel yoke of a hybrid composite propeller shaft for automobile is required. In this work a press fitting method for joining of an aluminum tube to an aluminum yoke is devised by a steel ring with many small teeth to increase reliability as well as to reduce manufacturing cost of the hybrid propeller shaft rather than using other joining methods such as adhesively bonded or welded joints. The optimal shape and number of teeth of the steel ring were obtained experimentally for the maximum static torque capabilities and fatigue characteristics of the press fit joint, and was compared to the finite element analysis results. Finally, a design guideline for the press fit joint using a steel ring with many small teeth for joining the aluminum shaft to the steel ring was suggested. With the developed press fit joint, the static average shear strength of 70 MPa and fatigue strength of 21 MPa between the aluminum tube and the steel ring were realized, which were almost three times higher than that of the adhesively bonded joint.

Improvement of Torsional Fretting Fatigue Strength of Splined Shaft Used for Car Air Conditioner's Compressor by Hybrid Joint

To improve the fretting fatigue strength of splined shaft used for compressor of car air conditioner, press-fit joint was combined with the spline joint. Torsional fretting fatigue strength of the combined jointed shaft was evaluated focusing on the effect of press-fit interference which must be secured when the combined joint is applied to the production process. Torsional fretting fatigue strength of the splined shaft was drastically increased by the combination of press-fit. The improvement was achieved by sharing transmitted torque between press-fit and spline. While fretting fatigue failure occurred at the press-fitted part when the press-fit interference was relatively small, the combined jointed shaft had four times higher fatigue strength than the conventional splined shaft. The increase of press-fit interference prevented the fretting fatigue failure and brought further increase of the fatigue strength, since amount of relative slip was significantly reduced by the increase of contact pressure.

Experimental Analysis of Static and Fatigue Strength Properties in Press-Fitted and Adhesively Bonded Steel–Aluminium Components

Press-fitted and adhesively bonded joints (Hybrid Joints) are increasingly used as an alternative way to traditional structural joining techniques. The main achievable benefits can be summarized in the possibility of maximizing the load transfer (torque or axial) and reducing both the weight and the stress field of the components, by taking advantage of the adhesive strength. Hybrid joints studies can be found in literature mainly on steel–steel components (Steel Hybrid Joints). The aim of this paper is to provide some relevant information on the static and fatigue strength properties in the case of steel–aluminium components (Mixed Hybrid Joints), from the experimental tests performed on a high strength, single-component adhesive which cures anaerobically. The use of the adhesive increases the press-fitted joint performances, with respect to its release force: the adhesive static shear strength is about 9 MPa, whereas the adhesive endurance limit is about 6 MPa, in presence of a stress ratio R = 0.1.

Functional outcomes following ceramic total joint replacement for hallux rigidus

The aim of this study was to evaluate functional outcomes following ceramic arthroplasty used in the treatment of osteoarthritis of the hallux metatarsophalangeal (MTP) joint. Thirty-seven consecutive patients who underwent press-fit ceramic joint arthroplasty were identified. Joint movement, gait pressure studies, radiographs, patient's outcome based on the American Orthopaedic Foot and Ankle Society (AOFAS) scale, hallux metatarsal phalangeal-interphalangeal index (HMPI) and visual analogue pain scales were assessed. Mean follow-up was 33 (12-60) months. Ninety-two percent of patients were satisfied with the surgery. AOFAS and HMPI scores were good to excellent in more than 90%. Six implants had lucent lines of greater than 2mm at 18 months. Three of these joints also had subsidence of both components. There was no correlation between implant loosening and patient outcomes. Mean hallux pressure at toe-off decreased from 7.1 to 3.5 N cm⁻² (p<0.01) equalising with normal contralateral toe pressure. Three patients required revision surgery and one patient had a transient wound infection. Good to excellent results have been achieved following ceramic total MTP joint arthroplasty. The clinical relevance of progressive lucencies around the implant is uncertain and longer follow-up may identify subsidence and ultimate failure.

Ultrasonic quality control of press-fit joints

A technique for quantitatively evaluating the quality of interference-fit joints by the echopulse method is proposed. A formula is obtained for calculating the value of the coefficient of ultrasound reflection from the site of the joint fit from the measured amplitudes of echo pulses in a free ring and in an assembled joint. It is shown that the reflection coefficient is the main parameter characterizing the quality of an interference-fit joint, i.e., its ability to withstand loads, determined by the maximum value of the torque transferred by a pressure joint, because the reflection coefficient is related to the normal stresses at the contacting surfaces of the joint. To optimize the process of studying the quality of a joint, it is noted that the automation of the testing procedure using the proposed technique is possible and desirable.

Experimental investigation of the thermal properties of tailored expansion lattices

Composite bimaterial lattice structures which possess both low, tailorable thermal expansion and nearly optimal stiffness have been proposed for applications which require high structural stiffness in environments which include large temperature fluctuations, such as the surfaces of high-speed aerospace vehicles. An experimental validation of the thermal properties of these lattices when they are constructed of practical materials with easily manufactured bonded joints is contained herein. Bonded lattices, comprising aluminum and titanium alloys, have been manufactured with press-fit dovetail joints and tested in a variety of thermal environments. Results for equilibrium heating, rapid transient heating and thermal cycling leading to shakedown are presented and shown to be consistent with theoretically and numerically attained results.

Structural damping caused by micro-slip along frictional interfaces

Damping in built-up structures is often caused by energy dissipation due to micro-slip along frictional interfaces (e.g., at bolted joints), which provides a beneficial damping mechanism and plays an important role in the vibration behavior of such structures. A careful study of the micro-slip phenomenon has been carried out using the finite element method. Two classical joint configurations, the press-fit joint and the lap-shear joint, have been used as the model problems. The focus of this paper is to evaluate the effect of dry friction on the damping response of frictional joint interfaces, to understand the evolution of the slip and stick regions along a joint interface during loading, and to quantify the amount of energy dissipation during cyclic loading and its dependence on structural and loading parameters. Finite element predictions are found to compare well with experimental measurements and are used to examine the validity and limitations of early analytical treatments in the literature.