Rubber Joint Research Articles

Analysis of mechanical stresses in silicone rubber joint tubes using a hyper-elastic model

A 2D model of a silicone rubber joint tube is proposed to calculate mechanical pressure. An analysis of radial and circumferential stresses within a joint tube based on a hyper-elastic model, employing finite element method is presented. This paper shows that assuming a constant elastic modulus for rubber leads to miscalculation of stresses within the joint tube. In addition, restricting the expansion ratio without considering the material’s elasticity could elevate the possibility of introducing high circumferential stress. Depending on the elastic modulus and expansion ratio, these circumferential stresses may approach 50% of the material’s tensile strength however, none of the simulated materials showed any critical values. A rigid semiconducting deflector could potentially generate significant circumferential stress, especially at the deflector-joint insulation interface, posing an increased risk if the material is relatively weak. Achieving the required pressure with stiffer materials necessitates a lower expansion ratio, while softer materials demand higher expansion ratios to accomplish the necessary pressure levels.

Investigating nonlinear dynamic properties of a swing arm rubber joint and their effects on the dynamic behavior of high-speed trains

The rubber joints mounted on swing arms provide the main part of the yaw stiffness for wheelsets and thus have a significant influence on the dynamic behaviour of railway vehicles. However, their nonlinear dynamic properties concerning the frequency, amplitude, and temperature were not fully considered in previous studies, most of which adopt simple models such as the Kelvin–Voigt model to represent rubber components. This study aims to investigate the radial nonlinear properties of swing arm rubber joints under various conditions and assess their effects on the dynamic performance of high-speed trains. A nonlinear rubber spring model which combines the fractional derivative Zener model with Berg’s friction model is established. To achieve a better fit to the measurements of a swing arm rubber joint, an optimisation-based method is employed to identify the model parameters. The viscous and frictional effects of the rubber joint are compared at different frequencies, amplitudes, and temperatures, by determining the predominant element of the nonlinear model. Additionally, the nonlinear rubber spring model is integrated into a high-speed vehicle dynamic model to investigate the effects of the nonlinear properties of swing arm rubber joints on the vehicle dynamic behaviour through the MATLAB/SIMPACK co-simulation method.

Experimental study and modeling of rubber joints for railway vehicles using magnetorheological shear stiffening elastomers

With the rapid development of transportation industry, advanced rail vehicle technology receives more attention than ever. The stiffness of the train’s rubber joint at the primary suspension system has a crucial influence on the operation stability and curve-passing performance. When the train is running on straight track at high speed, a high primary longitudinal stiffness in bogie design is required, whereas running on the curve track calls for a soft primary longitudinal stiffness. To solve this critical problem, a new rubber joint based on magnetorheological shear stiffening elastomer (MSSE) was proposed. Its stiffness can be adjusted by not only external magnetic field but also its inherent frequency-dependent property, ensuring the functionality of the rubber joint even when the controller fails. The prototype of the MSSE joint was fabricated and assembled. Stiffness controllability of the MSSE joint was evaluated using an material testing system (MTS) machine, with MTS testing performed under varying displacement amplitude at fixed frequency to investigate the influence of the varying displacement amplitude on the effective stiffness. The results revealed that the stiffness of this MSSE joint can be controlled effectively credited to the rate-dependent SSE and adjustable electromagnetics, exhibiting exceptional fail-safe characteristics. Lastly, a dynamic model was established to describe the dynamic performance of the rubber joint. All the above studies demonstrate the feasibility of the joint to satisfy the conflicting stiffness requirements to achieve high speed stability and curve trafficability simultaneously.

Investigating the Influence of Joint Reinforcements of Portland Cement Concrete Slabs Under Asphalt Concrete Overlays on Vertical Deflections Using Accelerated Pavement Testing

Joint gaps between slabs in underlying Portland cement concrete (PCC) pavements are critical factors in the life span of asphalt concrete (AC) overlays. Therefore, being informed about the vertical deflections that may occur around the joints is important. In this study the joints were reinforced with three different materials: ethylene propylene diene monomer (i.e., rubber joint filler [RJF] reinforcement), bitumen-based sealant (i.e., rubber plate [RP] reinforcement), and steel plate (SP) (i.e., SP reinforcement), to limit the vertical movement of the underlying PCC. Tests were conducted at the accelerated pavement testing facility for two different AC overlay thicknesses, 50 mm and 100 mm, during 100,000 passages to investigate the influence of AC overlay thickness variations on slab vertical deflections and to also evaluate types of joint reinforcement on slab vertical deflections. For 50-mm thick AC overlay, the most effective joint reinforcements to prevent deformations caused by loading were RP, RJF, and SP; for a 100-mm thickness, this was determined to be RJF, SP, and RP, respectively.

A physical model-neural network coupled modelling methodology of the hydraulic damper for railway vehicles

The dynamic characteristics of the hydraulic damper are time-varying in the complex working environment. To reveal the internal influence mechanism of the boundary conditions on the dynamic performance of the hydraulic damper and take it into account in the multi-body dynamics calculation, the laboratory test of the hydraulic damper is carried out firstly, and it is confirmed that the hydraulic damper has significant frequency-dependent and amplitude-dependent and temperature-dependent characteristics. Then, combining the physical parameter model with the neural network model, an accurate hybrid neural network model of the hydraulic damper is proposed. The physical parameter model considers the damper structure, including orifice, damping valve, rubber joint and the relationship between temperature and viscosity of hydraulic oil. The neural network model describes the personality characteristics of the hydraulic damper, such as oil leakage, the internal friction force and the percentage of entrapped air in oil. Finally, the responses and the dynamic parameters of the hybrid neural network model are calculated and compared with the experimental results by considering various exciting amplitudes and frequencies. The results show that the proposed model can fully simulate the dynamic performance of the hydraulic damper under various operating conditions.

Development of a magnetorheological elastomer rubber joint with fail-safe characteristics for high-speed trains

The stiffness of the train’s rubber joint at the primary suspension system has a crucial influence on the operation stability and curve-passing performance. As traditional rubber joint only provides unadjustable parameters, they cannot meet the conflicting stiffness requirements when the train is running at high speed on straight track and passing through the curve track. To solve this problem, this paper proposed a new rubber joint with fail-safe characteristics based on magnetorheological elastomer (MRE). The joint stiffness is controlled by a hybrid magnetic field generated by permanent magnets and electromagnets. With this hybrid magnetic field, the initial stiffness of the MRE joint can be designed to be hard so as to suppress the hunting motions and vibrations of wheelsets and thus keep the trains’ high-speed stability; furthermore, the stiffness can decrease by energizing the electromagnets when passing through a curve track. With this characteristic, the joint can guarantee the safety of the train at high operation speed even when the joint control system fails. The prototype of the MRE joint was fabricated and assembled. Stiffness controllability of the MRE joint was tested using a Material Testing Systems machine. The result reveals that the stiffness of this MRE joint can be controlled effectively. According to the testing results, a new phenomenological model was built to predict the joint’s dynamic performance. Then this established model was integrated into dynamic models of trains to numerically evaluate the new joint’s influence on the train’s stability and trafficability. The evaluation result shows that the proposed MRE joint is fully effective on providing controllable stiffness to satisfy the conflicting stiffness requirement with fail-safe characteristics.

Development of a magnetorheological elastomer rubber joint with fail-safe characteristics for high-speed trains

Abstract The stiffness of the train’s rubber joint at the primary suspension system has a crucial influence on the operation stability and curve-passing performance. As traditional rubber joint only provides unadjustable parameters, they cannot meet the conflicting stiffness requirements when the train is running at high speed on straight track and passing through the curve track. To solve this problem, this paper proposed a new rubber joint with fail-safe characteristics based on magnetorheological elastomer (MRE). The joint stiffness is controlled by a hybrid magnetic field generated by permanent magnets and electromagnets. With this hybrid magnetic field, the initial stiffness of the MRE joint can be designed to be hard so as to suppress the hunting motions and vibrations of wheelsets and thus keep the trains’ high-speed stability; furthermore, the stiffness can decrease by energizing the electromagnets when passing through a curve track. With this characteristic, the joint can guarantee the safety of the train at high operation speed even when the joint control system fails. The prototype of the MRE joint was fabricated and assembled. Stiffness controllability of the MRE joint was tested using an MTS machine. The result reveals that the stiffness of this MRE joint can be controlled effectively. According to the testing results, a new phenomenological model was built to predict the joint’s dynamic performance. Then this established model was integrated into dynamic models of trains to numerically evaluate the new joint’s influence on the train’s stability and trafficability. The evaluation result shows that the proposed MRE joint is fully effective on providing controllable stiffness to satisfy the conflicting stiffness requirement with fail-safe characteristics.

Numerical modelling of reinforced concrete frames with masonry infills and rubber joints

Masonry infill walls are critical components of reinforced concrete (RC) frames, which may be damaged even under earthquake events of moderate intensity, thus resulting in significant losses. Recent experimental and numerical studies have investigated innovative solutions for protecting these walls by reducing their interaction with the RC frame. Among these, specially shaped rubber joints were developed that can be inserted between the brick units, and between the masonry wall and the frame.In the present study, a novel computational modelling strategy is developed using ABAQUS to investigate the in-plane behaviour of RC frames with infill walls and rubber joints. The proposed approach employs three-dimensional solid finite elements to simulate the concrete components, 3D beam elements for the reinforcing bars, and a mesoscale approach for the infill wall with rubber joint. The numerical strategy is validated against two past experimental studies whose results can be found in the literature, one on RC frames with traditional infill walls, the other on RC frames with traditional walls and walls with rubber joints. The results shed light on the effectiveness of the rubber in minimising the in-plane seismic damage to the bricks, by localizing the deformation mostly in the rubber joints, and reducing the overall stiffness of the infilled system. Further analyses are carried out to investigate the effect of the rubber joints’ layout and stiffness on the behaviour and capacity of the system and its components.

Experimental study of adhesively bonded natural fibre composite – steel hybrid laminates

Natural fibre composites (NFC), such as flax fibre reinforced plastics are green material with good specific properties. Significant research is currently in progress to improve the mechanical properties and durability of these composites and to make them competitive to traditional synthetic composites. A multi-material design approach is proposed in this study to develop a novel hybrid structure with a thin metal layer adhesively bonded to NFC. Two adhesives; a commercial epoxy adhesive and natural rubber were used for the adhesion between a stainless steel layer and flax composite with thermoset and thermoplastic matrix. The performance of the hybrid joint was investigated using a single lap joint (SLJ) test supported by full-field displacement measurement methods. The manufacturing of the composite specimen and the bonding of the NFC – metal joint with rubber adhesive was demonstrated. The force displacement curves from the SLJ test showed that the bonded joint with epoxy adhesive was stronger in comparison to the bonding with natural rubber. It is supported by the adherend failure observed in the joint with epoxy adhesive, while the rubber joint showed adhesive failure. The key outcome of the research is that the viability of adhesively bonded NFC - metal hybrid is established.

Matching the Traction Qualities of Agricultural Mobile Power Vehicles with the Permissible Maximum Pressure on the Soil

Modern highly mechanized agricultural production is characterized by the incompatibility of simultaneous matching of the maximum pressure of agricultural mobile equipment movers on the soil and the possibility of increasing the tractors energy saturation when equipping them with existing wheel engines.(Research purpose)To coordinate the maximum pressure on the soil with the permissible norms, weight utilization factors and the level of tractors energy saturation.(Materials and methods)The authors used a calculated method for determining the maximum pressure on the soil using a universal tire characteristic.(Results and discussion)The authors found that when performing spring works on closing moisture and sowing row crops at a maximum pressure of 80 kilopascals, corresponding to all types of soil, the most mass universal row tractor Belarus 1020 had a maximum pressure of 150 kilopascals, which was 70 kilopascals higher than the permissible one for the corresponding crop shortage. They found that replacing ordinary tires with agrophilic tires could increase the area of the contact spot by 16 percent, while reducing the coefficient of unevenness and increasing the coefficient of use of the adhesion weight. The main condition for replacing ordinary tires with agrophilic tires was to keep the traction force unchanged.(Conclusions)Summarizing the results of the research as agrophilic direction, ensuring the compliance impacts on soil and positively solving the problems of saturation, it is possible to recommend the development of navigation systems in achieving utilization hitch weight equal to 0.5 (low tire pressure), equal to 0.6 (rubber joint with torsion bar suspension) and 0.7 (rubber track). It was found that the conducted research, taking into account the available data on traction tests of the T-250 tractor, would allow to include an agrophilic concept with a hypothetical dependence of the adhesion weight use factor on the longitudinal unevenness coefficient in the revised State Standard 27021-86 “Agricultural and forestry Tractors. Traction classes”.

Development of a smart rubber joint for train using shear thickening fluids

Developing a train bogie to achieve high speed stability as well as good curve passing performance has always been a challenge. This is because of the conflicting stiffness requirements: stability at high speed calls for a high primary longitudinal stiffness in bogie design, whereas for better performance through curves, a relatively soft primary longitudinal stiffness is required. To solve this parameter incompatibility, this paper proposes a new design which uses the shear thickening fluid (STF) structure as the stiffness changing component. This new joint was developed and then tested using MTS machine to characterize its frequency-dependent characteristics. MTS testing under varying displacement amplitude at fixed frequency was also performed to investigate the influence of the varying amplitude on the effective stiffness. At last, the performance of the proposed STF joint in terms of improving the train stability and the curving performance is numerically evaluated. The numerical evaluation results demonstrate that the adaptive STF rubber joint outperforms the conventional rubber joints in that it can satisfy the conflicting stiffness requirements to simultaneously achieve high speed stability and curve trafficability.

Study on the evolution of dynamic performance of high-speed EMU after long-term service

In order to find the influence of wheel and rail wear about dynamic performance of the high-speed railway vehicle in the actual operation process, a high dimensional strong nonlinear dynamic model of the high-speed vehicle is established, and measured wheel profile is used to characterize contact geometry between wheel and rail, and relationship between stiffness of steering rubber joint and dynamic performance of railway vehicle is studied in different wheel/rail wear state. Results show, With the increment of wheel and rail wear and equivalent conicity, that stability of hunting motion of vehicle decreases, stability and safety of the vehicle all deteriorate. Moreover, with the increment of longitudinal steering joint stiffness, critical speed, lateral stability and safety of vehicles increases gradually. When it goes above 17.5MN/m, with the increments of critical speed, lateral stability and safety tend to be stable. With the increment of lateral steering joint stiffness, critical speed of vehicle tends to increase first and then decrease, and finally tends to be stable around 5MN/m, which reaches the maximum when the stiffness is 2.5MN/m. Lateral stiffness of steering joint has little influence on lateral stability of the vehicle; At low equivalent conicity, vehicle running safety decreases slightly with the increment of lateral stiffness of steering joint, while equivalent conicity increases, the vehicle running safety deteriorates sharply with the increase of lateral stiffness of steering joint. In conclusion, in order to adapt to different equivalent conicity, the optional range of longitudinal stiffness of steering joint is suggested to concentrated in 5∼17.5MN/m, while its lateral stiffness is suggested to be within 2∼5MN/m.

Nonlinear finite element analysis and experimental study on the stiffness of rubber joint

ABSTRACT Rubber joint is a vital component widely used for rail vehicles. This paper presents a method to obtain effective stiffness for rubber joint by using an integrated design-simulation-testing-design procedure. A new type of rubber joint composed of steel and rubber was designed and produced for a CL242 bogie. It was taken as an example to establish a finite element model, and the effective stiffness of the structure under loading was obtained by ANSYS. The predicted stiffness was compared with test results measured in the laboratory, and the nonlinear finite element analysis results are in good agreement with the experimental curves, which shows that the finite element model is reliable. Furthermore, the effect of rubber-damping characteristics and structural parameters on the stiffness of rubber joint was studied based on the reliable finite element model. The FEA result shows that the radial and axial stiffness values decrease rapidly, as the value of rubber thickness h increases. However, there is an upward trend of the radial and axial stiffness with increasing of inclination angle a and rubber-damping characteristics. Therefore, the methodology used in this study could provide useful guidance for the structural design optimization and development of new rubber joints.

Damage evolution of tunnel lining with steel reinforced rubber joints under normal faulting: An experimental and numerical investigation

The zones where tunnels through the active faults are proved to be seriously damaged because of the fault dislocation which could be due to strong earthquakes. A steel reinforced rubber joint with flexibility and ductility is proposed in this paper. An experimental investigation of the responses and the damage patterns of the tunnel lining with the joints under normal faulting is presented. The results showed the damage of the lining with the joints in the model test was mainly concentrated in the fault areas because of the joints’ adjustment. No obvious shear failure was found in this test. Then, a nonlinear three-dimensional finite element (FE) model, using concrete damaged plasticity model, was performed to simulate the tunnel linings with the proposed joints and without joints under normal faulting. The numerical results show that the tunnel with the joints had step-like displacements without big relative displacement compared to the tunnel without joints. The joints efficiently decreased the maximum relative displacement between lining segments. The extent of the tensile damage area of the lining affected by normal fault was longer than that of the compressive damage area. And the tensile damage area was larger than the compressive damage area for either the lining with the joints or the lining without joints. There was no obvious difference in damage to the lining with and without joints in areas under compression loading. The joints efficiently decreased the extent of the damage in the zone with tensile stresses. The comparisons between the numerical predictions and experimental results show a good agreement.

Thermo-mechanical analysis of solid interfaces in HVAC cable joints

Mechanical stresses affect the electrical performance of solid-solid interfaces in high-voltage cable joints. This paper assesses the influence of insulation material mechanical properties and temperature on interface pressure. Based on a hyper-elastic model, the mechanical stresses inside silicone rubber joint tube were determined. Circumferential stresses can reach 50% of the silicone rubber tensile strength at normal pre-operation expansion ratios. An analytical method to determine the thermally induced mechanical stress during operation is presented and its accuracy is confirmed using finite element method. This method is modified to account for the variation of the mechanical properties with temperature. This paper shows that circumferential stresses at the interface increase as temperature drops, which may have a significant impact on the electrical performance of the interface during operation.

Analysis and Research on Rubber Joint of the Axle Box Rotary Arm of CRH3 EMU

In order to study the stiffness performance of rubber joint of axle box rotary arm for EMU, the rubber joint of axle box rotary arm for CRH3 EMU was studied by combining finite element analysis with experiment. The structural composition of rubber joint of axle box rotating arm and several strain energy functions of rubber hyperelastic materials are described. The material constants of Mooney-Rivlin and Ogden models are obtained by curve fitting of rubber material test data. The radial stiffness and the axial stiffness of the rubber joint of the axle box rotating arm are calculated by using the finite element simulation software, and the experimental verification is carried out at the same time. It is found that the results of Mooney-Rivlin and Ogden models are similar in the case of small deformation, and Ogden model is more accurate in the case of large deformation.

Testing of modified primary stiffness for heavy-haul locomotives operating on sharper-radius curves

For the typical wheelset drive subsystem with axle-suspended motor, the coupled vibration differential equations of wheelset and axle hung motor are derived. The mechanical model of traction rod is established. The subsystems are integrated into a whole locomotive-track coupled dynamic model which is verified from the aspects of load transfer and curving negotiation performance. To reduce the wheel–rail dynamic interaction of six-axle heavy-haul locomotive passing through curves in old existing lines, the parametric optimization flow of primary rubber joint is presented. The stiffness of 12 new rubber joints equipped in drawbars is tested and the stiffness dispersions are investigated. The research results show that, for a single rubber joint, the maximum and minimum values of radial stiffness can, respectively, increase and reduce by 16.2% and 33% with respect to the test mean value. For the assembled axle-box with upper and lower drawbars, the test longitudinal and lateral stiffness increase by 18% and 46%, respectively, relative to the designed values. A distinct dispersion phenomenon in the stiffness distributions of rubber samples is found. By combining with the numerical simulation results, the primary longitudinal stiffness is optimized from 199 MN/m to 52 MN/m, as the lateral stiffness changes from 6.89 MN/m to 2.6 MN/m. The final running test indicates that the optimized parameters can reduce the wheel–rail lateral force by 12% in the 300 m radius curve. The ride comfort could still keep in the same level, and the running stability has not been deteriorated.

Vertical Cyclic Performance of Precast Frame with Hook-end U-shaped High-damping Rubber Joint

High-damping rubber (HDR) has been commonly used to dissipate cyclic energy and reduce the bumping effect of a building structure. Studies on the application of HDR in precast reinforced concrete structures have mainly focused on the effects caused by lateral cyclic loads, but joints in precast structures are also highly susceptible to damage when frames are subjected to vertical cyclic loads. Therefore, this research aimed to develop a new hook-end U-shaped joint by using HDR so that the formation of cracks on precast frames could be minimized and the accumulated energy dissipation capacities could be enhanced under the actions of a vertical cyclic load. The developed joint was experimentally tested and compared with a single dowel beam-column-connected precast frame. Results revealed that the performance of the joint was similar to that of hysteresis loops and yield force. But, its maximum force and strength ratio were slightly lower than that of the control precast frame. A nonlinear 3D numerical model was also created and subjected to a vertical cyclic load to predict the behavior of the precast frame with the proposed and single dowel beam-column connections. Differences between numerical and experimental results were identified by comparing numerical data with experimental data.

Finite element analysis for components force of flexural rubber joint

Flexible rubber joint is an important connecting pipe fitting in ship and chemical industry. However, the problems existing in its application, especially the stress distribution for each component of rubber joint structure, were lack of theoretical analysis. Therefore the finite element model of rubber joint was established according to its structure in this study. With the help of software, the stress characteristics of rubber joint under the axial tension and periodic dynamic load were analysed with the standard maximum internal pressure load and flanges bolt pretension together. The calculation results showed that the order of maximum stress in rubber joint components from big to small was: reinforcement ring, cord layer and rubber skeleton. In order to reduce the stress value at the weak area in the rubber components, the angles of the cord were studied and found that when the cord angle were 60°/-60°for 1,3,5/2,4,6 layer respectively, the maximum stress value for the reinforcement ring and cord fabrics were reduced obviously. After the life computation by the software, it was confirmed that the cord angle arrangement 60°/-60°for cord layers could significantly improve the service life of the rubber joint.

Overcoming the conflict requirement between high-speed stability and curving trafficability of the train using an innovative magnetorheological elastomer rubber joint

The conflict requirement between high-speed stability and curving trafficability has been always a critical issue of train. This article proposed an innovative stiffness variable magnetorheological elastomer rubber joint, which contains two sets of electromagnetic coil, magnetorheological elastomer, and three iron flanks to overcome the conflict requirement. To characterize the proposed magnetorheological elastomer rubber joint, an MTS machine was used to test the field-dependent property, the amplitude-dependent performance, and the frequency-dependent response. The test results verified the stiffness variation capability of the proposed magnetorheological elastomer rubber joint. After the characterization, the magnetorheological elastomer rubber joint was then embedded onto a train model. In the simulation, different curve tracks and different train speeds were simulated to evaluate the effectiveness of the magnetorheological elastomer rubber joint on reducing the angle of attack. Additionally, the critical speeds of the train models were tested and compared when the magnetorheological elastomer rubber joint was working in softened and stiffened mode, respectively. The simulation results demonstrated that the magnetorheological elastomer rubber joint can offer soft and hard wheelset positioning stiffness under different requirements so that both the high-speed stability and curve trafficability of the train can be guaranteed.