Single Rubber Research Articles

Investigation of rheological properties and modification mechanism of bio-oil/crumb rubber modified asphalt reinforced by fiber

The synergistic effects of crumb rubber (CR), epoxy soybean oil (ESO) and polyester fiber (PF) on rheological and comprehensive properties of asphalt and the modification mechanism were studied. The main objective is to address the challenges of high viscosity and incompatibility associated with single rubber modified asphalt, as well as oil volatilization and decomposition at high temperatures, and decreased high temperature performance of oil /CR modified asphalt. The response surface method was used to optimize the ratio of PF, ESO and CR, and the ideal mixing ratio of 0.294 % PF, 6.0 % ESO and 21.464 % CR was determined by analyzing the interaction characteristics of each pairwise of the three components to obtain the best rheological properties. The rheological results showed that PF improved the rheological properties at high temperature and ESO improved the rheological properties at low temperature. Compared with the traditional SBS modified asphalt, the three-component composite modified asphalt exhibited excellent low temperature rheological properties and enhanced fatigue resistance, which was due to the synergistic effect between PF, ESO and CR. Microscopic analysis showed that ESO effectively enhances the compatibility and phase structure of the composites, while PF promoted structural stability by limiting the flow of asphalt. In this study, the comprehensive effects of single-component modified asphalt and multi-component modified asphalt were analyzed and compared by radar map, and the advantages of three-component modified asphalt were obviously highlighted. This study provides valuable insights and scientific guidance for the technical progress of similar asphalt modification engineering.

IMPROVING THE SEALING EFFECT OF AN ECCENTRIC DOUBLE-DOOR HYDRAULIC PACKER

This research's primary goal is to identify ways for enhancing the hydraulic packer with eccentric power's molding impact and removing any potential causes. Since they ensure the efficacy of multi-stage hydraulic fracturing, packers are a well-known and essential component of hydraulic fracturing operations in low-permeability reservoirs. Packers enable the application of hydraulic pressure to specific wellbore segments. However, packer cuffs need to be dependable and have long-lasting qualities in order to survive formations subjected to high pressure and temperature (such as 80 MPa and 150 °C). In this study, a software program is employed to numerically optimize the rubber cuff constructions of the packer through trials, and the findings are verified. The rubber cuff with a regular structure serves as the starting point for the optimization process. The software then identifies the weakest places and improves them by making minor structural changes. The final, optimal construction of the expandable cuff is achieved by repeating this process. The findings demonstrate that the single rubber barrel's optimized construction works incredibly well in horizontal wells for packer rubbers and expanding reserve rings. Keywords: Packer collar, shaping effect, structure optimization, packer.

Prediction and evolution of core-shell morphology and their effect on mechanical properties of PP blends

The prediction of phase morphology is highly valuable in designing and regulating the properties of multiphase composites, particularly polymer blends. In this study, we prepared two types of ternary blends, PP/HDPE/EPR and PP/HDPE/EPDM composites and compared and analyzed the predicted and observed phase morphology of blends with different elastomers. Using Palierne and Bousmina equations, we calculated the interfacial tensions between two components in PP blends and then predicted the relationship between the spreading coefficient, interfacial tension, and phase morphology according to the spreading coefficient theory. Based on our findings, it was observed that the core-shell structure of EPR and EPDM rubber phase encapsulated HDPE core tends to form in PP ternary blends, which aligns with our experimental results. Additionally, SEM morphology observation results revealed a less number of dispersed phases in PP/HDPE/EPR composites with the same composition ratio. It was observed that the shell had a greater thickness due to the difficulty in dispersing EPR with higher viscosity. Mechanical tests indicated that composites with thin-shell and small-core dispersed phases had better toughness. These composites also displayed less yield strength loss under the same impact conditions compared to those with single rubber phases.

Isoprene polymerization catalyzed by iron (II) and cobalt(II) complexes carrying 2,6‐bis(1H′‐allylbenzimidazolyl)pyridyl ligand

AbstractThe incorporation of cis‐1,4 and 3,4(+1,2) units is important to the overall properties of polyisoprene. Nevertheless, polymerization to prepare such polymer via coordinative‐insertion method has less reported. In the present study, 2,6‐bis(1H’‐allyl‐benzimidazolyl)pyridine has been installed onto the iron and cobalt prior to heterogeneous supporting. They are shown to be amenable to homogeneous polymerization of isoprene, affording 3,4(+1,2) units enriched polymer. The addition of disulfide carbon into cobalt catalyst is decisive for boosting productivity and elevating 3,4 (+1,2) insertion. Whereas, diethylphosphite external donor merely behaves as a chain transfer agent in iron catalyzed polymerization. The produced polymer with a controlled 3,4(+1,2) ratio and molar mass may find application as a single rubber, in polymer blends, composites, adhesives, and as a versatile platform for transforming to a wide range of functional polymer.Highlights Novel iron and cobalt complexes are made. High activities toward isoprene polymerization are achieved. 3,4(+1,2) incorporated polyisoprene is obtained.

A 3D Lidar SLAM System Based on Semantic Segmentation for Rubber-Tapping Robot

Simultaneous localization and mapping (SLAM) in rubber plantations is a challenging task for rubber-tapping robots. Due to the long-term stability of tree trunks in rubber plantations, a SLAM system based on semantic segmentation, called Se-LOAM, is proposed in this work. The 3D lidar point cloud datasets of trunks collected in rubber plantations of Hainan University are used to train the semantic model, and the model is used to extract features of trunk point clouds. After clustering the trunk point clouds, each single rubber tree instance is segmented based on the Viterbi algorithm. The point clouds of tree instances are fitted to the cylindrical trunk models for semantic cluster association and positional estimation, which are used for lidar odometry and mapping. The experimental results show that the present SLAM system is accurate in establishing online mapping, and the location of the trunk in the map is clearer. Specifically, the average relative pose error is 0.02 m, which is better than the positioning performance of LOAM and LeGO-LOAM. The average error of estimating the diameter at breast height (DBH) is 0.57 cm, and it only takes 401.4 kB to store a map of the area of approximately 500 m2, which is about 10% less than other classic methods. Therefore, Se-LOAM can meet the requirements of online mapping, providing a robust SLAM method for rubber-tapping robots.

Misusing Elastics for Midline Diastema Closure - Disaster and Treatment Via a Case Report in Vietnam

Midline diastema has been a popular aesthetic problem for children. Several treatment options are available, however, the use of elastic bands without other appliances for closing the diastema still remains a pressing issue in Vietnam, which could be done by the patient’s parents either themselves or under the dental practitioners’ suggestion. Objective: To report a specific case about the extensive extrusion regarding upper central incisors in a pediatric patient due to misusing the elastic band, in which management was complex due to an unfavorable situation for splinting. Case Report: Single rubber band usage for orthodontic movement in closing diastema has been an unresolved disaster in Vietnam, leading to the need for early diagnosis and immediate intervention when facing the complications. Conclusion: Significant information dissemination is paramount for long-term improvement in the oral health of pediatric patients in Vietnam and around the world.

Synergistic effect of compound rubber and SiO2 nanoparticles on low-temperature toughening and balanced stiffness-toughness of random copolymer polypropylene nanocomposites

Random copolymer polypropylene (PPR)/rubber/silica nanocomposites with excellent low-temperature toughness and balanced rigidity-toughness were prepared by using compound rubber composed of ethylene propylene rubber (EPR) and isoprene rubber (IR). Effects of compound rubber on reinforcement and toughening of PPR were systematically investigated through mechanical properties, dynamic mechanical behavior, morphologies and rheological behavior. Mechanical results showed compound rubber had higher efficiency in both reinforcement and toughening than single rubber. According to morphological analysis and rheological results, it was found that the EPR/IR compound rubber had a better distribution in PPR matrix due to the close viscosity to PPR matrix and maintained the characteristics of silica distribution at the interface between rubber and matrix. Dynamic mechanical results revealed PPR/compound rubber blends showed larger area of loss factor. Consequently, the better toughening effect and achieving good rigidity-toughness balance of compound rubber in PPR nanocomposites was ascribed to the synergistic effect of compound rubber and SiO2 nanoparticles, which results in smaller particle spacing and larger loss factor area of rubber phase in nanocomposites without changing preferential loading of nanoparticles at polymeric interface.

Multitraction with a single rubber band and clips: a simple tip for endoscopic submucosal dissection of a recurrent lesion with previous clip.

Endoscopic submucosal dissection (ESD) with double-clip traction (DCT) with a rubber band and two clips allows excellent en bloc and curative resection rates and is probably the cheapest traction system available [1]. Incomplete previous resection or recurrence is associated with a higher piecemeal resection rate [2] and severe fibrosis is an independent predictor of perforation [3]. DCT is also safe and effective in these settings [4]. Multipolar traction has been reported to improve the visualization of the submucosa with four peripheral rubber bands fixed with four clips on the edges and attached to a central band that is fixed on the opposite wall with a fifth clip [5]. This is effective but requires some time to set up the device, which can be difficult to advance up through a thin operative channel.

Experimental study and mathematical modeling of viscoelastic dampers with wider temperature range based on blended rubber matrix

The glass transition temperature of existing viscoelastic (VE) materials is low, usually under 0 °C, thus the desired damping performance for VE dampers cannot be achieved at room temperature. On this issue, this study investigated the feasibility of utilizing blended rubber matrix to widen the working temperature range of VE materials, thereby improving the energy dissipation capacity at room temperature. A series of VE material samples based on blended rubber matrix were prepared, and the optimal formula was selected and applied in the fabrication of VE dampers. Then, the performance tests of VE dampers based on blended rubber matrix and single rubber matrix were conducted and compared. Results show that VE dampers based on blended rubber matrix have wider temperature range and better energy dissipation capacity than those based on single rubber matrix. A mathematical model for VE dampers based on blended rubber matrix was proposed by combining the internal variable theory and the temperature-frequency equivalence principle, and the accuracy of the proposed model was verified by comparisons between the calculated results and experimental data.

The Effect of Particle Shape on the Compaction of Realistic Non-Spherical Particles—A Multi-Contact DEM Study

The purpose of this study was to investigate the deformation behavior of non-spherical particles during high-load compaction using the multi-contact discrete element method (MC-DEM). To account for non-spherical particles, the bonded multi-sphere method (BMS), which incorporates intragranular bonds between particles, and the conventional multi-sphere (CMS), where overlaps between particles are allowed to form a rigid body, were used. Several test cases were performed to justify the conclusions of this study. The bonded multi-sphere method was first employed to study the compression of a single rubber sphere. This method's ability to naturally handle large elastic deformations is demonstrated by its agreement with experimental data. This result was validated further through detailed finite element simulations (multiple particle finite element method (MPFEM)). Furthermore, the conventional multi-sphere (CMS) approach, in which overlaps between particles are allowed to form a rigid body, was used for the same objective, and revealed the limitations of this method in successfully capturing the compression behavior of a single rubber sphere. Finally, the uniaxial compaction of a microcrystalline cellulose-grade material, Avicel® PH 200 (FMC BioPolymer, Philadelphia, PA, USA), subjected to high confining conditions was studied using the BMS method. A series of simulation results was obtained with realistic non-spherical particles and compared with the experimental data. For a system composed of non-spherical particles, the multi-contact DEM showed very good agreement with experimental data.

Design and Performance Research of Single Rubber Cylinder for High Pressure Gas Injection Packer

In order to solve the problem of "gas explosion" at the end of common rubber cylinder in the process of high temperature, high pressure and gas drive operation, the rubber cylinder with new structure suitable for 51/2in casing pipe is developed. The "M" type single rubber cylinder structure is adopted in the new structure rubber cylinder, and the "gas explosion" problem of the end gas in the low-pressure side is solved by setting the double-layer staggered slotted steel cover to prevent outburst. The finite element method is used to simulate the setting of the rubber cylinder, and the structural parameters of the new rubber cylinder are obtained by single factor analysis and orthogonal optimization, simulation test and seal test were carried out to verify the sealing performance of the rubber cylinder. According to the actual working condition, the simulation test results and seal test results show that the sealing capacity of the packer reaches 50MPa under the temperature resistance of 120℃, and the end steel cover is fully opened to wrap the rubber cylinder, which meets the operation requirements of high temperature and high pressure gas injection packer.

Preparation of FKM/EFEP thermoplastic vulcanizate with excellent heat and oil resistance, gas barrier property and recyclability

Because of the fuel diversification, the harsher use environment and the requirements of environmental protection, the automotive fuel pipeline system requires not only good mechanical properties and high elasticity but also high temperature and oil resistance, high gas barrier property, easy processibility, and recyclability. Nevertheless, the traditional materials cannot simultaneously meet the requirements of these properties. In this study, fluororubber (FKM)/fluoro-thermoplastic (EFEP) TPV (FTPV) with fine dispersion of FKM rubber phase in EFEP matrix was successfully produced through the design and optimization of crosslinking systems of FKM and the processing technology. The as prepared FTPV not only shows good mechanical properties, elasticity, rheological property and recyclability, but also excellent oil resistance and gas barrier properties, outperforms the other TPVs. The mechanism on morphological development of the FKM/EFEP TPV are revealed. Interestingly, a large number of single rubber sub-micron particles (RPs) are formed in the blend during the dynamic vulcanization, which is mainly attributed to an improvement in compatibility and an increase in crosslinking degree of FKM. The combined effect of shearing stress and the improvement of compatibility results in a decrease in the size of rubber sub-micron particles agglomerates and an increase in the content of single rubber sub-micron particles.

Highly Articulated Tube Mechanism With Variable Stiffness and Shape Restoration Using a Pneumatic Actuator

Recently, soft robotics research has focused on mechanisms to control the stiffness of robot structures. There are several types of variable stiffness mechanisms that can change the stiffness of such structures by altering friction force. Among these, the negative-pressurization method applies negative pressure to the particles or layers that are filled inside a bag so that they contact each other and increase stiffness. However, the maximum driving pressure that can be achieved using the negative-pressurization method is 0.1 MPa, which limits the stiffness. In this study, we devised a new fluid-driven mechanism that can change the stiffness through positive pressurization using pneumatic artificial muscles. The proposed structure constructed with hollow beads and inner muscles can hold arbitrary joint angles by the contraction force generated when a pressure is applied. We measured the torque in the pitch direction due to friction when the internal pressure and inner segment diameter were changed. We confirmed that the error between the measured and theoretical torque value was within a 20% at any inner diameter. Also, since a pneumatic artificial muscle is enclosed inside the structure, an actuation effect can occur when the pressure is applied. We measured the restoring angle and force of this effect when the valve opening ratio and inner segment diameter were changed. We confirmed the function that can change the shape restoration characteristics by changing the flow rate with a single rubber tube. Our approach will help design effective stiffening mechanisms using positive pressurization in soft robotics applications. In future, we will design a tensioner mechanism for arbitrarily changing the distance of segments in the axial direction, and we will investigate the holding torque, restoring angle and force when the distance of the segments is changed.

ENHANCING PERFORMANCE OF MECHANICALLY OPERATED PACKER

During hydraulic fracturing operations of low-permeability reservoirs, packers are the key component to ensure the success of multistage fracturing. Packers enable sections of the wellbore to be sealed of and separately fractured by hydraulic pressure, one at a time, while the remainder of the wellbore is not afected. However, reliable sealing properties of the packer rubber are required to meet the high-pressure and high-temperature (HPHT) conditions of reservoirs (such as 70 MPa and 170 °C). In this study, the structures of the packer rubber with two diferent materials are optimized numerically by ABAQUS and validated by experiments. The optimization process starts from the packer rubber with a conventional structure, and then, the weakest spots are identifed by ABAQUS and improved by slightly varying its structure. This process is iterative, and the fnal optimized structure of a single rubber barrel with expanding back-up rings is achieved. For the structure of three rubber barrels with metallic protective covers, both HNBR and AFLAS fail under HPHT conditions. For the fnal optimized structure, the packer rubber made of AFLAS can work better under HPHT than that made of HNBR which ruptures after setting. The results show that the optimized structure of a single rubber barrel with expanding back-up rings and the material AFLAS are a good combination for the packer rubber playing an excellent sealing performance in multistage fracturing in horizontal wells. Keywords: packer rubber, sealing property, structure optimization, hydrogenated nitrile–butadiene rubber (HNBR), AFLAS rubber.

The supernumerary rubber hand illusion revisited: Perceived duplication of limbs and visuotactile events.

A controversial and unresolved issue in cognitive neuroscience is whether humans can experience supernumerary limbs as part of their own body. Some previous experiments have claimed that it is possible to elicit supernumerary hand illusions based on modified versions of the rubber hand illusion. However, other studies have provided conflicting results that suggest that only one rubber hand can be perceived as one's own. To address this issue, we developed a supernumerary hand illusion paradigm that allowed us to disambiguate ownership of individual rubber hands from simultaneous ownership of two fake hands. In our setup, the participant's real right hand was hidden under a platform, while two identical right rubber hands were placed in parallel on top of the platform in direct view of the participant. We applied synchronous strokes to both rubber hands and the real hand (SS), synchronous strokes to one rubber hand and the real hand and asynchronous strokes to the other model hand (AS and SA), or asynchronous strokes to both fake hands in relation to the real hand (AA). Our results demonstrate that a genuine illusion of owning two rubber hands can be elicited and that such a supernumerary hand illusion can be isolated from the sense of ownership of a single rubber hand both in terms of questionnaire ratings and threat-evoked skin conductance responses (SCRs). These findings advance our knowledge about the dynamic flexibility and fundamental constraints of body representation and emphasize the importance of correlated afferent signals for causal inference in body ownership. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Mathematics of Securing a Box With a Single Rubber Band

Mathematics of Securing a Box With a Single Rubber Band

Band ligation-assisted endoscopic mucosal resection of an intradiverticular polyp.

With over 140,000 new colorectal cancer cases anticipated in 2020 by the American Cancer Society, colonoscopy remains a standard of care in the screening and further evaluation of precancerous colorectal lesions.1Joseph D.A. Meester R.G.S. Zauber A.G. et al.Colorectal cancer screening: estimated future colonoscopy need and current volume and capacity.Cancer. 2016; 122: 2479-2486Crossref PubMed Scopus (133) Google Scholar Although a trained gastroenterologist is able to routinely perform screening colonoscopies as part of daily practice, the location of some polypoid lesions might pose a challenge. Colonic diverticula pose a particular challenge because they lack or have a weakened layer of muscularis propria owing to focal wall weakness and increased intraluminal pressures,2Gulwani H. Diverticulosis. Gulwani H. Diverticulosis.https://www.pathologyoutlines.com/topic/colondiverticulosis.htmlDate accessed: May 16, 2020Google Scholar thus increasing the risk of perforation with intervention. We present the case of a healthy 50-year-old man who was seen for routine colonoscopy and was found to have diverticular disease and a polyp arising from a diverticulum in the descending colon. A healthy patient presented to the endoscopy suite for routine colonoscopy. The examination showed diverticulosis of the sigmoid colon and, within the descending colon, a 7-mm polyp within the base of a diverticulum. The adjacent area was tattooed with India ink, and the remainder of the screening colonoscopy was completed and the colonoscope was withdrawn. At this time, the colonoscope was exchanged, and a single-channel upper forward-viewing endoscope (GIF-HQ190, Olympus, Tokyo, Japan) with a band ligating device attached to its tip (MBL-6-XL-C, Cook Medical, Bloomington, Ind, USA) was subsequently used. The diverticulum with the attached polyp was found by drawing attention to the mucosa previously marked with India ink within the descending colon (Fig. 1). Once the diverticulum was identified, full intermittent suction was performed to drive the diverticulum into the device, with resulting inversion of the diverticulum and the polyp. Intermittent suction allowed us to minimize the possibility of muscularis propria being present within the banded tissue. A single rubber band was deployed on the colonic wall from which the diverticulum originated (Fig. 2). After confirming the banding, the polyp was subsequently resected via hot snare polypectomy performed at the surface of the diverticulum, leaving the diverticulum intact with complete removal of the polyp and an R0 margin. The diverticulum was then retrieved for further histological examination, which revealed tubular adenoma (Fig. 3).Figure 3A, Hot snare polypectomy performed on inverted diverticular polyp. B, Base of diverticulum after hot snare polypectomy.View Large Image Figure ViewerDownload Hi-res image Download (PPT) The patient tolerated the procedure well without any further adverse events and was discharged home on the same day. One week after the procedure, the patient was contacted and reported that he remained symptom free. Techniques to remove early neoplasms of the GI tract include polypectomy, endoscopic mucosal resection, endoscopic submucosal dissection, and, recently, the use of a full-thickness resection device. However, polyps arising within or near colonic diverticula pose an increased challenge to the gastroenterologist because of the increased risk of perforation. To minimize this risk, new techniques such as endoscopic full-thickness resection have been developed, which allows for complete resection of the lesion3Mão de-Ferro S. Castela J. Pereira D. et al.Endoscopic full-thickness resection of colorectal lesions with the new FTRD system: single-center experience.GE Port J Gastroenterol. 2019; 26: 235-241Crossref PubMed Scopus (12) Google Scholar; nevertheless, despite its increased availability, it still requires additional training and poses additional costs. Alternative techniques, including band ligation of suspected lesions, have also been proposed to allow for induced ischemia and necrosis, resulting in the ligated contents falling off. However, as presented by Carmo et al,4Carmo J. Marques S. Chapim I. et al.Elastic band ligation for the removal of a colonic tubular adenoma in a diverticulum.Endoscopy. 2015; 47: E490-E491Crossref PubMed Scopus (6) Google Scholar using band ligation alone limits histopathological analysis because no specimen is collected. By using the technique presented here, the polyp is safely removed and can still be sent for further histopathological analysis. The techniques and instruments readily available to the majority of gastroenterologists can be used, and no additional costs are incurred in comparison with full-thickness resection device usage (Video 1, available online at www.giejournal.org). All authors disclosed no financial relationships. eyJraWQiOiI4ZjUxYWNhY2IzYjhiNjNlNzFlYmIzYWFmYTU5NmZmYyIsImFsZyI6IlJTMjU2In0.eyJzdWIiOiJmMzcyNDc2OGM3ZmEwZjI5MjQzMzEwNjZkZGQ3YTg4YSIsImtpZCI6IjhmNTFhY2FjYjNiOGI2M2U3MWViYjNhYWZhNTk2ZmZjIiwiZXhwIjoxNjc3ODY1MzExfQ.Z_zOqWWL5rI6fGhT9_wbG0TAsVlAyN9nSJJyyyO05lMlyRf0XXZsLxUhGsapj0ZrbNrAnlqYP0HiWGJk6xpjb9UxgPZ5yuyONIROBtBDeBWFytxWV-AJIpVouaClJlJsqc7e4WvTh_sTDwfbRvEhArIs2iiXbE4euhluEcPo1-hC3cO36XYJqk_AX-50P4LxXrSPcb7CFDtfKRAMiuDWBObq9gJl3NQJZeZx_TJTNYM2QFWNbNMm1oy9bLwyiCMCrSctz2Cuq6vy6_1UH0MemiL-zB4eF-KG4jO-qEQb8ryR10AaKvv2GptYWb1RnHVGtHWm8ri7epADvO8Z9jvfpw Download .mp4 (61.52 MB) Help with .mp4 files Video 1Band ligation-assistded endoscopic mucosal resection of an intradiverticular polyp.

Experimental Study on the Strengthening Properties of Rubber Concrete with Hook End Steel Fibers

The fast development of automobile sector, removal of discarded waste elastic is turning into a broad ecological problem. In the current work, exertion has been made to limit this problem By using scrap elastic as the scrap (morsel) concrete rubber in various percentages, as a partial replacement for the fine aggregates. In this paper, the mechanical properties of rubberized concrete with steel fibre (RSFC) are studied experimentally. This article discussed the effect by volume of concrete (5, 7.5 and 10 per cent rubber) and (0.8.0.1 and 1.2 per cent steel fibre) on the reinforcement of the properties of rubberized concrete with steel fibres (RSFC) of scrap crumb rubber (SCR) and steel fibre (SF) with different steel substances. The literature survey suggests that there is a substantial decline in strengths of the single morsel rubber used in traditional concrete. like compressive, tensile and flexural strength therefore to overcome this problem by using steel fibers in present investigation and from the results it can be finalized that the all the strengthening properties (compressive, tensile strength and flexural strength) are increased contrasted with rubberized concrete but still test values are inferior than conventional concrete due to fineness of crumb rubber and irregular shape of hook end steel fiber.

An Evaluation of Shoe Tread Parameters using FEM

Within this paper, a three-dimensional finite element (FE) model of a uniformly loaded, single rubber block, is described and run using loading conditions replicative of a standard slip resistant footwear test. The FE model considers rubber hyperelastic and viscoelastic material properties, obtained using dynamic mechanical analysis. The performance of the FE model was evaluated through analytical compression analysis and experimental contact area testing. The effect of tread grooves was investigated with relation to slip-resistance during walking. Analysis and discussion are provided of the tread model's sliding contact areas, contact pressure, stress, and front edge mechanics.

Static and dynamic stability analysis of a steel-rubber isolator with rubber cores

Stability is one of the most important parameters to evaluate seismic base isolators. Previous research has illustrated the power of base isolators with single and multiple rubber cores. While that work provided a critical introduction to this innovative idea, the lateral stability of seismic steel-rubber base isolators with single and multiple rubber cores was not evaluated; thus it is the topic of the current work. The finite element method is used for modeling of the elastomeric bearing. Three methods, including reduced area formula, quasi-static, and dynamic analysis, were used. The Ogden method is used for modeling rubber material properties. The effect of the size and number of rubber cores on the stability of elastomeric bearing is also investigated. The obtained results show that the use of single and multiple rubber cores increases isolator stability due to the large critical vertical loads. Also, the results of quasi-static methods and dynamic analysis for single rubber core isolators showed that increasing the core diameter has a slight effect on stability. A comparison of the results from the quasi-static and dynamic analysis shows a good agreement, confirming that the simpler quasi-static method is effective to numerically measure the stability limit of steel-rubber base isolators.