Metal Spacer Research Articles

Improvement in CPP-GMR read head sensor performance using [001]-oriented polycrystalline half-metallic Heusler alloy Co2FeGa0.5Ge0.5 and CoFe bilayer electrode

ABSTRACT A current-perpendicular-to-plane giant magnetoresistive (CPP-GMR) device with a half-metallic electrode is one of the most promising candidates of next-generation read head for hard disk drive. In this study, we fabricate [001]-oriented polycrystalline CPP-GMR devices with the normal ferromagnet (NFM) CoFe/half-metallic ferromagnet (HMFM) Co2FeGa0.5Ge0.5 (CFGG) bilayer electrodes to enhance the magnetoresistance (MR) ratio by large interfacial spin-dependent scattering at the NFM/HMFM interface. The CoFe/CFGG bilayer electrode provides the additional large interfacial spin-dependent scattering and achieves high MR ratio of 22.7% with the CoFe(4.5 nm)/CFGG(2.5 nm) bilayer electrodes, which is almost three(two) times larger than the MR ratio with the single CoFe(CFGG) (7 nm) electrodes. The bias voltage dependent study revealed an additional advantage of increasing the output voltage |ΔV| by using the CoFe/CFGG bilayer due to the improvement of the endurance against spin-transfer torque under high bias current. A maximum output voltage Δ V max of 6.5 mV was obtained with the CoFe(5.5 nm)/CFGG(1.5 nm) electrodes, which is the highest ever reported in the CPP-GMR devices with a uniform metallic spacer including high-quality epitaxial devices.

Experimental validation of the Betti’s Analytical Method for Double Glass Units

The structural response of Insulating Glass Units (IGUs), formed of glass plates sealed by perimeter metal spacers entrapping a gas, is strongly influenced by the complex interaction between the glass plates and the gas, as well as by the structural coupling of the plates through the spacers. The former effect, called “load sharing”, depends on the flexural stiffness of the plates and the pressure variation of the compressible gas due to applied actions. The more accurate and direct model to evaluate the load sharing is the recently proposed Betti’s Analytical Method (BAM) (soon included in the new Eurocode on structural glass), which allows to evaluate the IGUs response under the most various support conditions and external loads. In this paper, the BAM model is revisited, and the result obtained by means of conjugate BAM-numerical analyses are carefully validated by means of comparison with the results of experimental tests. In particular, the results of an extensive experimental campaign, performed on Double GUs (DGUs) subjected to line-distributed and concentrated loads, both at the environmental and at high temperature, are presented. To properly account for the influence of geometric parameters on the DGU response, elements with various aspect ratio, glass thickness and cavity thickness have been considered.

Improvements in thermoelectric features by resonant-tunneling magnetic tunnel junctions with β-Ga2O3 semiconductor

A study was conducted to investigate thermoelectric effects (TEEs) in resonant-tunneling magnetic tunnel junctions (RTMTJs) featuring wide-bandgap semiconductors such as ZnO and β-Ga2O3, along with a non-magnetic metal spacer. The transmission function was determined using the non-equilibrium Green’s function method within a tight-binding model. Significant enhancements in TEEs were observed for the β-Ga2O3 semiconductor compared to other materials, indicating its potential applicability in the emerging field of β-Ga2O3 spincaloritronics.

Magnetization switching driven by spin current in a T-type ferromagnetic trilayer

The T-type CoFeB/spacer/CoFeB structure is a promising candidate for the development of perpendicular spin–orbit torque (SOT) magnetic random-access memory and other SOT devices. It consists of an in-plane magnetized layer, a perpendicularly magnetized layer, and a non-magnetic metal spacer that induces interlayer exchange coupling. By engineering the W spacer, this system achieves field-free SOT switching with a nearly 100% switching ratio. Furthermore, it realizes a high exchange coupling field of 255 Oe using a relatively thinner spacer thickness, enhancing the reliability and energy efficiency of SOT switching. Measurement of current switching probability suggests that this perpendicular magnetic anisotropy system may enable the implementation of probability-adjustable true random number generators in future applications. The T-type structures with strong interlayer coupling exhibit great potential for spintronic device applications.

Fusion Rates in Tibiotalocalcaneal Arthrodesis with Tantalum Coated Metal Cup Augmentation

Introduction/Purpose: Tantalum coated metal spacers (TCMS) have recently been utilized to fill and provide structure to large bony defects in the hindfoot. Tantalum is an appealing material due to its biocompatibility, lack of immune response generation, and structural integrity. Compared to custom printed spacers and bulk allografts, TCMS are readily available off-the-shelf implants with significantly less cost. There is currently a paucity of literature assessing the use and outcomes of TCMS in foot and ankle surgery, specifically in tibiotalocalcaneal (TTC) arthrodesis. This study serves to assess clinical outcomes and fusion rates of patients who underwent TTC arthrodesis utilizing intramedullary nailing with TCMS augmentation for large bony defects. Methods: We retrospectively identified all patients > 18 years of age who underwent TTC arthrodesis with TCMS augmentation at our tertiary care center between 2015-2021. We also identified all patients who underwent TTC arthrodesis without augmentation within that time frame. The computed tomography (CT) scans at the six-month postoperative point were reviewed by one board-certified orthopaedic foot and ankle surgeon to determine fusion status, which was defined as having at least 50% fusion mass. Patient-reported outcomes measures (PROMs) including the modified foot function index (FFI) and PROMIS Global Mental Health Score were collected for patients in both groups. Patient demographics, clinical outcomes, and PROMs were compared between groups. A multivariate logistic regression model measured the effect of TCMS augmentation on the likelihood of achieving fusion. Results: Of the 65 patients included, 21 patients (32.3%) underwent TTC with TCMS augmentation. There were no significant differences in demographics between the two groups. Patients in the TCMS group had significantly higher modified FFI (91.1 + 47.6 vs 26.3 + 48.8, p< 0.001) and PROMIS Global Mental Health (12.2 + 4.82 vs. 5.59 + 6.76, p< 0.001) scores in the postoperative period. Overall, the fusion rate was higher for the TCMS group, however the difference was not significant between groups (90.5% vs. 80.5%, p=0.472). Multivariate logistic regression identified that TCMS augmentation was a nonsignificant predictor of increased odds of fusion at the six-month postoperative point (OR=2.87, p=0.232). Conclusion: This study is the largest to date to present 6-month postoperative CT scans demonstrating successful TTC fusion with TCMS augmentation, contributing to our understanding of its utility. Given the severity of disease and bone loss in the TCMS group, it is not surprising that post-operative patient reported outcome scores differed significantly compared to the control group. TCMS augmentation can be utilized as cost effective spacers to fill large defects in TTC arthrodesis with successful union rates. Further studies are needed to evaluate the efficacy of TCMS augmented fusions as a viable substitute to custom printed cages. Figure 1: Weight-bearing anteroposterior and lateral ankle radiographs of a patient with post-traumatic ankle arthritis and previously treated chronic osteomyelitis with valgus malalignment (A). Anteroposterior and lateral ankle radiographs status post TCMS augmented TTC arthrodesis (B). Coronal and sagittal CT scans demonstrating bony union through the TCMS augment (C).

Enhancement of spin to charge conversion efficiency at the topological surface state by inserting normal metal spacer layer in the topological insulator based heterostructure

In this study, we report efficient spin to charge conversion (SCC) in the topological insulator (TI) based heterostructure (BiSbTe1.5Se1.5/Cu/Ni80Fe20) by using spin-pumping technique, where BiSbTe1.5Se1.5 is the TI and Ni80Fe20 is the ferromagnetic (FM) layer. The SCC, characterized by inverse Edelstein effect length (λIEE) in the TI material, gets altered with an intervening Copper (Cu) layer, and it depends on the interlayer thickness. The introduction of Cu layer at the interface of TI and FM metal provides a new degree of freedom for tuning the SCC efficiency of the topological surface states. The significant enhancement of the measured spin-pumping voltage and the increased linewidth of ferromagnetic resonance absorption spectra due to the insertion of Cu layer at the interface indicate a reduction in spin memory loss at the interface that resulted from the presence of exchange coupling between the surface states of TI and the local moments of FM metal. The temperature dependence (from 8 to 300 K) of the evaluated λIEE data for all the trilayer systems, TI/Cu/FM with different Cu thicknesses, confirms the effect of exchange coupling between the TI and FM layer on the SCC efficiency of the topological surface state. This study offers promising ways for designing more efficient spin-charge conversion devices of the TI-based heterostructure by controlling the interface effects.

Solar-driven surface-heating membrane distillation using Ti3C2Tx MXene-coated spacers

The emergence of two-dimensional (2D) MXenes as efficient light-to-heat conversion materials offers significant potential for solar-based desalination, particularly in photothermal interfacial evaporation, enabling cost-effective solar-powered membrane distillation (MD). This study investigates solar-powered MD afforded by a photothermally functionalized spacer, which is built by spray-coating Ti3C2Tx MXene sheets on metallic spacers. 2D Ti3C2Tx MXene gives an ultrahigh photothermal conversion efficiency; thereby, by Ti3C2Tx MXene-coated metallic spacer, this rationally designed spacer allows for a localized photothermal conversion and interfacial feed heating effect on the membrane surface, especially for MD operation. As a feed spacer and a photothermal element, Ti3C2Tx MXene-coated metallic spacer exhibited stable enhanced water flux of up to 0.36 kg·m−2h−1 under one sun illumination for a feed salinity of 35 g·L−1, corresponding energy conversion efficiency of 28.3 %. Overall, the developed photothermal Ti3C2Tx MXene-coated spacers displayed great potential in enhancing the performance, scalability, and feasibility of solar-driven MD process, paving the way for further development of photothermal elements that can be implemented in solar MD applications.

Radial head replacement for acute complex elbow instability: a long-term comparative cohort study of 2 implant designs.

Radial head fractures not amenable to reconstruction should be treated by radial head replacement (RHR) when there is associated elbow or forearm instability. There are multiple RHR designs with different philosophies, but 2 of the most commonly used implants include the anatomic press-fit radial head system and the loose-fit metallic spacer. There is little information available specifically comparing the long-term clinical and radiographic outcomes of these 2 systems. The objective of this study was to compare the long-term clinical and radiologic outcomes of 2 RHR designs in the context of complex acute elbow instability. Ninety-five patients with an average age of 54 years (range, 21-87 years) underwent an acute RHR (46 press-fit Acumed anatomic and 49 loose-fit Evolve metallic spacer) and were prospectively followed for an average of 61 months (range, 24-157 months). There were 34 terrible triads; 36 isolated RH fractures with medial, lateral, or longitudinal instability; and 25 RH fractures associated with a proximal ulnar fracture. Clinical outcome and disability were evaluated with the Mayo Elbow Performance Score (MEPS), the Oxford Elbow Score, and the Disabilities of the Arm, Shoulder, and Hand (DASH) score. Pain and satisfaction were assessed using a visual analog scale. Radiographic analysis included presence of loosening, bone loss, and overstuffing related to the RHR. Eight patients with an anatomic RHR (2 with overstuffing, 3 for stiffness, and 3 with loose implants) and 1 patient with a spacer (with stiffness) required implant removal. There were no significant differences between spacer RHR and anatomic RHR in arc of motion (120° vs. 113°, P=.14), pain relief (1 vs. 1.7, P=.135), MEPS (94 vs. 88; P=.07), Oxford Elbow Score (42.3 vs. 42.2, P=.4), or DASH score (12.2 vs. 14.4, P=.5). However, patients with a spacer RHR were significantly more satisfied (9 vs. 7.7; P=.004) than those with an anatomic implant. Radiographically, 19 anatomic implants had significant proximal bone loss and 10 showed complete lucent lines around the stem. Lucent lines were common around the spacer RHR. These radiographic changes were not always related to worse clinical outcomes. Both the anatomic and spacer RHR designs can provide good clinical long-term outcomes. However, patients with a spacer showed a higher degree of satisfaction and those with an anatomic press-fit RHR had a higher revision rate, with radiographic changes that warrant continued follow-up.

PT‐Symmetry Enabled Spintronic Thermal Diodes and Logic Gates

AbstractDevices for performing computation and logic operations with low‐energy consumption are of key importance for environmentally friendly data processing and information technology. Here, a design for magnetic elements that use excess heat to perform logic operations is presented. The basic information channel is coupled non‐conductive magnetic stripes with a normal metal spacer. The thermal information signal is embodied in magnetic excitations and it can be transported, locally enhanced, and controllably steered by virtue of charge current pulses in the spacer. Functionality of essential thermal logic gates is demonstrated by material‐specific simulations. The operation principle takes advantage of the special material architecture with a balanced gain/loss mechanism for magnetic excitation which renders the circuit parity‐time symmetric with exceptional points tunable by the current strength in the spacer. Heat flow at these points can be enhanced, be non‐reciprocal, or may oscillate between the information channels enabling controlled thermal diode and thermal gate operations. The findings point to a new route for exploiting heat for useful work on the nanoscale.

Fusion Rates in Tibiotalocalcaneal Arthrodesis with Tantalum Coated Metal Cup Augmentation

Category: Ankle Arthritis; Ankle Introduction/Purpose: Tantalum coated metal spacers (TCMS) have recently been utilized to fill and provide structure to large bony defects in the hindfoot. TCMS have a porous structure and elastic modulus similar to cancellous bone, increasing resistance to collapse, as well as osteoconductive properties that allow for bony ingrowth. At this time, there is still a paucity of literature assessing the use and outcomes of TCMS in foot and ankle surgery, more specifically as bridging structures for large bony defects when performing tibiotalocalcaneal (TTC) arthrodesis. This study serves to assess clinical outcomes and fusion rates of patients who underwent TTC arthrodesis utilizing intramedullary nailing with tantalum coated metal cup augmentation for large bony defects. Methods: We retrospectively reviewed the charts of 20 patients who underwent TTC fusion with TCMS augmentation at our local tertiary care center between 2015-2021. The CT scans at the six-month post-operative window were reviewed by one orthopaedic surgeon to determine the presence of bony fusion, which was defined as having at least 50% fusion mass. From the initial cohort, we collected the following modified foot function index scores for 13 patients: PROMIS Physical Health (0-20), PROMIS Mental health (0-20), Foot Function Index (0-170), Activity Limitation Scale (0-30), Pain Scale (0-50) and Disability Scale (0-90). Results: The mean age of our cohort was 53.9 (± 12.9) with a mean CCI of 1.54 (± 1.127) and mean follow up of 451.5 days (± 353.3). Mean modified foot function index scores included: PROMIS Physical Health 12.15 (± 3.34), PROMIS Mental health 12.23 (± 4.82), Foot Function Index 91.08 (± 47.59), Activity Limitation Scale 15.00 (± 10.42), Pain Scale 25.00 (± 14.77) and Disability Scale 51.00 (± 25.06). The post-operative complication rate was 30.8% in which 3 patients required a revision surgery via nail dynamization and one patient required a below knee amputation due to an infected nonunion of the TTC arthrodesis. The overall fusion rate at the 6-month postoperative visit was 69.2%. Conclusion: Unlike prior studies, we were able to obtain 6-month post-operative CT scans to delineate successful fusions with a larger number of patients (n=13). Given the paucity of literature looking at TCMS augmented fusions in foot and ankle surgery, our data will contribute to our understanding and efficaciousness of this relatively new use of TCMS in foot and ankle surgery. Further studies are needed to evaluate the efficacy of TCMS augmented fusions as a viable surgical approach as well an alternative to standard nail dynamizations with structural grafts.

Laminated Polymer‐Encapsulated Halide Perovskite Photoconductors

AbstractHerein, a simple, solvent‐free method to fabricate polymer‐encapsulated halide perovskite photoconductors is described. Dry mechanochemical synthesis is used to prepare CsPbBr3 in the presence of poly(butyl methacrylate) (PBMA). The resulting composite powder is then heated and pressed into a free‐standing disk with a thickness controlled by a metallic spacer ring. The disk can be laminated on a glass substrate patterned with interdigitated electrodes, resulting in a planar photoconductor device. The best photoconductive performance is obtained for disks that consist of 75 wt.% CsPbBr3 in PBMA, reaching a detectivity of ≈2 × 1011 Jones. Moreover, by adjusting the thickness of the disk, narrowband detectors can be obtained due to charge collection narrowing. Depending on the thickness of the pressed disk, the position and width of the detectivity peak can be tuned. At last, the disks are tested as possible absorber materials for X‐ray detectors, where ow detection limit, and fast and linear response are measured for perovskite‐polymer disks with 50 wt.% perovskite content. This work shows a simple and versatile approach toward the fabrication of halide perovskite photodetectors, which can be carried out in air and without the use of solvents.

Zn(II) Metal–Organic Frameworks with a Long Spacer Ligand and a Tricarboxylate Coligand

The preparations and structural characteristics of three-dimensional Zn(II) metal-organic frameworks (MOFs) with dipyridyl-olefin and tricarboxylate are reported. The solvothermal reactions of zinc(II) nitrate hexahydrate, 1,4-bis [2-(4-pyridyl)ethenyl]benzene (bpeb), and 4,4′,4″,-benzene-1,3,5-triyl-tris(benzoic acid) (H3btb) furnished three Zn(II) MOFs (1–3) with new topologies. Depending on the temperature or mole-ratio variations, self-interpenetrated [Zn2(bpeb)(btb)(OH)]·DMF·H2O (1), noninterpenetrated [Zn3(btb)2(bpeb)]·xSolvent (2), and fourfold interpenetrated [Zn2(Hbtb)2(bpeb)][Zn2(Hbtb)2(bpeb)][Zn4(Hbtb)4(bpeb)2] (3) structures were generated with different molecular building blocks. It is interesting that although all three MOFs contain the same metal cation, anion, and spacer ligand, they show different emissions due to structure and connectivity.

First-Principles Studies on Spin-Dependent Transport of Magnetic Junctions with Half-Metallic Heusler Compounds

Two types of magnetoresistance (MR), i.e., tunnel magnetoresistance (TMR) and current perpendicular to plane giant magnetoresistance (CPP-GMR), are theoretically discussed for systems with half-metallic (HFM) Co-based full Heusler compounds. In TMR, the non-collinear spin structure at the Co2MnSi(CMS)/MgO(001) interface that results from thermal spin fluctuations significantly reduced the TMR ratio at room temperature (RT). Enhancement of the exchange stiffness of CMS/MgO was essential to suppress the reduction in TMR at RT. Furthermore, it is proposed that inserting of a B2-CoFe layer between CMS and MgO is a promising way to enhance the interface exchange stiffness constant. In CPP-GMR, the interface spin asymmetry γ in the Valet-Fert model was essential to enhance GMR at RT, because the temperature dependence of γ in experiments was much larger than that of the bulk spin asymmetry β. I showed that the experimental CPP-GMR ratio increases with the decrease in the theoretical resistance-area product RPA, which is roughly consistent with the RP dependence of γ. This means that matching of the conductive channel between HMF and a non-magnetic metallic spacer is a key parameter to enhance γ. These findings will be very important for room temperature spintronics devices applied in future artificial intelligence hardware.

A Wideband Antenna Calibration Network Using Multi-Layer Coupling Technology

In this paper, the design methodology of an antenna calibration network using multi-layer stripline-slotline coupling is proposed. A multi-layer coupler and a two-stage Wilkinson power divider are designed to ensure the basically stable amplitude-phase characteristics of coupling and achieve the wide frequency band. To minimize phase imbalance, the lengths of channels should be kept equal to the maximum extent possible. In addition, the transmission line conversion structure is applied at each port for integration with the antenna array. Aiming at the problems of signal crosstalk and mutual coupling, the isolated via holes are installed near the lines and metal spacers are placed over the ports. By using the semi-closed structure, part of substrates is dug out to expose the resistor welding position. A semi-closed calibration network in series-parallel-fed is fabricated to verify the design methodology. In 8-16 GHz, the amplitude-phase characteristics are considerable, in which the coupling is 37-44 dB and phase deviation is below 8∘. The isolation between ports T1-T16 is greater than 33 dB and voltage standing wave ratio (VSWR) of them is lower than 1.8.

Independent transmitted and reflected colors enabled by Fano resonant optical coatings

Conventionally, optical coatings transmit and reflect the complementary colors due to the limitations of the resonant modes in multilayered structures. Here, we experimentally demonstrate a type of semi-transparent optical coating that can produce the same color in transmission and reflection based on Fano resonance. The results verify that when the metallic spacer is extremely thin, almost the same reflectance and transmittance spectra can be simultaneously achieved with the efficiency about 40%. Furthermore, we comprehensively explore the change of the colors by varying the thickness of the metal and the refractive index of the dielectric cap. Benefiting from the flexible tuning of the coupled resonator, a broad palette of colors and chromatic information display are presented. Our semi-transparent optical coatings exhibit viewing angle tolerance up to 40°, which may lead to novel display and optical anti-counterfeiting techniques.

A novel T-shaped high-power waveguide phase shifter with continuous linear phase adjustment.

A novel T-shaped high-power waveguide phase shifter is investigated in this paper. The phase shifter consists of straight waveguides, four 90° H-bend waveguides, a stretching metal plate, and a metal spacer linked with the stretching metal plate. The entire structure for the phase shifter is symmetrical along both sides of the metal spacer. The phase-shifting principle for the phase shifter is to change the microwave transmission path by moving the stretching metal plate and then realize the linear phase adjustment. An optimal design approach of the phase shifter based on the boundary element method is described in detail. On this basis, a T-shaped waveguide phase shifter prototype with a center frequency of 9.3GHz is designed. Simulation results show that the phase shifters can achieve 0°-360° linear phase adjustment by altering the distance of the stretched metal plate to 24mm, and the efficiency of power transmission is more than 99.6%. In the meanwhile, experiments were conducted and the test results are in good agreement with simulation results. The return loss is more than 29 dB, and the insertion loss is less than 0.3 dB at 9.3GHz in the entire phase-shifting range.

Oscillatory exchange bias controlled by RKKY in magnetic multilayers

Ferromagnetic/antiferromagnetic bilayers are interfaced with normal metal/ferromagnetic bilayers to form F*/AF/N/F valves. The N-spacer thickness is chosen such that it mediates strong indirect exchange [Ruderman–Kittel–Kasuya–Yosida (RKKY)] between the outer ferromagnetic layers, which varies in strength/direction depending on the N thickness and changes its direction on switching F. The system exhibits a strong modulation of the F*/AF exchange bias, oscillating in strength synchronously with the oscillation in the interlayer RKKY exchange across the normal metal spacer. The effect is explained as due to a superposition taking place within the antiferromagnetic layer of the direct-exchange proximity effect from the F*/AF interface and the indirect RKKY exchange from F penetrating AF via N. The modulation, expressed via the strength of the F*/AF bias field, reaches 400% at the first RKKY peak.

An optimization study on the performance of hot water tank integrated phase change material

In this paper, a new structure of a phase change thermal storage tank is proposed with the aim of enhancing the thermal storage capacity of the domestic hot water tank without occupying the water storage volume. The structure of the proposed tank is that the phase change material is filled in the outer side wall of the tank and the cavity formed by an insulation layer, which does not occupy the water storage space inside the tank. The cavity is equipped with metal spacers in parallel with each other as a method to strengthen heat transfer. The effects of three structural design parameters, namely the thickness of phase change material, the number and thickness of spacers on the charging and discharging process were investigated by the means of numerical calculations. A numerical model was developed by using COMSOL Multiphysics, and the accuracy of the model was verified with experimental data from the literature. The average temperature of phase change material, average water temperature, and liquid/solid phase fraction were used to evaluate the thermal performance of the phase change thermal storage tank.It was found that the low thermal conductivity of the phase change material affected the thermal performance. When the thickness of the phase change material was 30 mm, the discharging time was prolonged by 10 %, which was 5 h longer than the common water tank. The installation of metal spacers was an effective method to enhance heat transfer. During the charging process, the phase change material had a stronger liquefaction trend, and the lowest value of the solid fraction was 0.25. During the discharging process, when the number of spacers was 17 and the thickness was 5 mm, the discharging time was extended to 80 h, which was 1.5 times of the common water tank. The results help to understand the optimized design parameters of the phase change thermal storage tank from the perspective of the structural design.

Wideband Calibration Network for Multichannel Antenna Array Feeding Network

In this letter, a wideband calibration network using multilayer coupler is proposed for <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">X</i> -band antenna array feeding network. A high performance coupler is designed to ensure consistency for the coupling of the series-fed structure. By using a serpentine feedline and making all channels the same length, phase imbalance is decreased. To reduce lateral leakage, cross-talk and mutual coupling, the vias-shielded structure and metal spacer are used. To validate the proposed calibration network design, a wideband calibration network is fabricated and measured. Measured results show that the coupling amplitude fluctuates mainly in the range of 29–37 dB with phase imbalance less than 5°, the isolation of all ports is better than 38 dB and voltage standing wave ratio is less than 1.7.

Finite element analysis on strength and durability of spherical laminated elastomeric bearings

Elastomeric bearings consist of alternating rubber and metal spacer layers bonded via vulcanization technique. As important structural components in aerospace and bridge construction as well as other industries, the reliability of elastomeric bearings has a significant impact on the safety of the whole system. In this work, the finite element method is used to study the stress and displacement distributions of spherical laminated elastomeric bearings during helicopter flight, and then the theory of cumulative fatigue damage is used to analyze the fatigue lifetime of the bearing. By means of the comparative analysis of six single-load cases and a multiple-load case of the bearing categorized from the viewpoint of helicopter flight characteristics, the main influencing factors and how they affect the stress and displacement distributions are revealed. Finally, a durability test is conducted and the experimental results are well consistent with the calculated results, which indicates the prediction accuracy of the model. The work would be beneficial to the optimal design and reliable service of elastomeric bearings.