Browse Topic: Elastomers
Electric vehicles (EVs) are particularly susceptible to high-frequency noise, with rubber eigenmodes significantly influencing these noise characteristics. Unlike internal combustion engine (ICE) vehicles, EVs experience pronounced variations in dynamic preload during torque rise, which are substantially higher. This dynamic preload variation can markedly impact the high-frequency behaviour of preloaded rubber bushings in their installed state. This study investigates the effects of preload and amplitude on the high-frequency dynamic performance of rubber bushings specifically designed for EV applications. These bushings are crucial for vibration isolation and noise reduction, with their role in noise, vibration, and harshness (NVH) management being more critical in EVs due to the absence of traditional engine noise. The experimental investigation examines how preload and excitation amplitude variations influence the dynamic stiffness, damping properties, and overall performance of
Mechanical analysis was performed of a non-pneumatic tire, specifically a Michelin Tweel size 18x8.5N10, that can be used up to a speed of 40 km/h. A Parylene-C coating was added to the rubber spoke specimens before performing both microscopic imaging and cyclic tensile testing. Initially, standard ASTM D412 specimens type C and A were cut from the wheel spokes, and then the specimens were subjected to deposition of a nanomaterial. The surfaces of the specimens were prepared in different ways to examine the influence on the material behavior including the stiffness and hysteresis. Microscopic imaging was performed to qualitatively compare the surfaces of the coated and uncoated specimens. Both coated and uncoated spoke specimens of each standard type were then subjected to low-rate cyclic tensile tests up to 500% strain. The results showed that the Parylene-C coating did not affect the maximum stress in the specimens, but did increase the residual strain. Type C specimens also had a
This paper investigates the development of a Finite Element model of a Mixed Service Drive truck tire sized 315/80R22.5 equipped with thermal simulating properties. The physical experiments were performed at a high-speed track in Hällered, Sweden for the truck combination travelling at a constant speed of 80 km/h. For this investigation, the Gross Combination Weight is approximately 42 metric tons. In the Finite Element Analysis environment, ESI Virtual Performance Solutions, the truck tire is designed with hyperelastic Ogden solid rubber definitions. The Ogden material definition is used in this application as it is more suitable to perform thermal and wear analysis within the Finite Element environment. The Finite Element truck tire model is simulated to increase in two different temperature rates. The truck tire model simulates the thermal build-up over time for select tires on a High-Capacity transport truck combination, particularly a driven tire on the tractor. Finite element
As a crucial connecting component between the powertrain and the chassis, the performance of rubber mounts is directly related to the NVH (Noise, Vibration, and Harshness) characteristics of electric vehicles. This paper proposes a double-isolation rubber mount, which, compared to traditional rubber mounts, incorporates an intermediate skeleton and features inner and outer layers of “cross-ribs”. The design parameters can be simplified to: skeleton diameter, skeleton thickness, main rib width, and main rib thickness. To comprehensively evaluate its performance, a finite element analysis (FEA) model of the proposed double-isolation rubber mount was first established in Abaqus, with static stiffness and dynamic performance analyzed separately. The results indicate that, compared to traditional rubber mounts with similar static stiffness, this design effectively controls dynamic stiffness in the high-frequency range. To expand the effective vibration isolation frequency range of the
In this article, a finite element analysis for the passenger car tire size 235/55R19 is performed to investigate the effect of temperature-dependent properties of the tire tread compound on the tire–road interaction characteristics for four seasons (all-season, winter, summer, and fall). The rubber-like parts of the tire were modeled using the hyperelastic Mooney–Rivlin material model and were meshed with the three-dimensional hybrid solid elements. The road is modeled using the rigid body dry hard surface and the contact between the tire and road is modeled using the non-symmetric node-to-segment contact with edge treatment. At first, the tire was verified based on the tire manufacturer’s data using numerical finite element analysis based on the static and dynamic domains. Then, the finite element analysis for the rolling resistance analysis was performed at three different longitudinal velocities (10 km/h, 40 km/h, and 80 km/h) under nominal loading conditions. Second, the steady
This material type has resistance to hot air, but generally has poor resistance to fuels and lubricants, but usage is not limited to such applications. Each application should be considered separately. This material type has a typical service temperature range of -85 to 500 °F (-65 to 260 °C). The operating temperature range of the material is a general temperature range, but the presence of particular fluids and design parameters may modify this range. Recommendations on the material selection are based on available technical data and are offered as suggestions only. Each user should make his own tests to determine the suitability for his own particular use.
Soft-bending actuators are gaining considerable attention in robotics for handling delicate objects and adapting to complex shapes, making them ideal for biomimetic robots. Soft pneumatic actuators (SPAs) are preferred in soft robotics because to their safety and compliance characteristics. Using negative pressure for actuation, it enhances stability by reducing the risk of sudden or unintended movements, crucial for delicate handling and consistent performance. Negative pressure actuation is more energy-efficient, safe and are less prone to leakage, increasing reliability and durability. This paper involves development of a new soft pneumatic actuator design by comparing various designs and to determine its performance parameters. This paper depicts on designing, and fabricating flexible soft pneumatic actuators working under negative pressure for soft robotic applications. The material used for fabrication was liquid silicone rubber and uniaxial tensile tests were conducted to
The article describes a two-step technique that involves making a masterbatch that is 3:1 [by weight] carboxylated nitrile rubber (XNBR) and nanoclay (NC), compounding on a two-roll mill, and moulding at 150°C and 20 MPa pressure. Tensile strength (TS), elongation at break (EB), and modulus (M100, M200 and M300) all rises with the amount of nanofiller present, peaked at 5 phr, then fell off. The NC demonstrated a tendency to aggregate at greater concentrations. The amount of reinforcement provided by the NC filler can be determined by comparing the modulus of filled compounds (M100f) to that of unfilled XNBR (M100u). This ratio rises with the amount of NC present, peaked at 5-7.5 phr, and subsequently fell. Using sorption isotherms, the swelling behaviour of the solvent through the nanocomposites was studied. With increasing NC concentration, the solvent absorption fell, reaching a minimum at 5 phr NC. When toluene sorption for diffusion via XNBR-NC composites was measured, the amount
Polypropylene has been the plastic traditionally used in the manufacture of bumpers. Composite materials have been presented as an alternative due to lightness and sustainability. This article presents a composite of polyester resin and jute fiber fabric as an innovative alternative to be studied for the manufacture of automotive bumpers. Composite material was manufactured for characterization. It was used as matrix the terephthalic polyester resin, unsaturated and pre-accelerated, and the catalyst MEK V388 for curing the composite. The chosen reinforcement was the jute fiber fabric. Silicone molds with dimensions according to ASTM 3039 were used to manufacture specimens, and subsequent tensile strength test to determine properties and compare with literature data. The composite with jute fiber reinforcement with alignment 0°/0°/0° was evaluated as viable for the application in car bumpers, having its value of tensile strength surpassed that of the composite reinforced by jute fiber
This study investigates the efficiency of a compression ignition (CI) engine powered by biodiesel derived from rubber seed oil (RSO) and its various blends. This research aims to assess the feasibility of using RSO biodiesel as a substitute fuel in CI engines to reduce harmful emissions and the depletion of fossil fuels. Initially, the process of obtaining rubber seed oil was preceded by transesterification. After transesterification, the same was blended in different proportions with conventional diesel in B20, B40, B60, B80, and B100. Results show that brake thermal efficiency (BTE) decreased with rising concentration of biodiesel, particularly at higher blends. B100 had a 20-25% lower BTE in every load condition than conventional diesel. The brake specific fuel consumption (BSFC) generally decreased with increasing biodiesel content, particularly at lower loads applied to the engine. B100 portrayed a perceptible improvement of 25.6% in BSFC compared diesel at 1 kg load. This
Linear dynamics simulations are performed on engine components to ensure structural integrity under dynamic loading. The finite element model of the engine assembly must be prepared accurately to avoid under or over design of the engine components. Flexible hoses are present at pipe routings and modeling them in simulations is a challenge because the stiffness of the composite is not known. The hose under study in this paper is a rubber composite with a knitted reinforcement layer. A multiscale modelling approach is presented to characterize the hose stiffness. A representative volume element geometry i.e., unit cell representation of the composite, consisting of the knitted yarn and surrounding rubber is used to establish orthotropic elastic properties at microscale, by performing finite element homogenization using the ANSYS material designer module. The homogenized properties are assigned to the macroscale hose geometry to perform modal analysis simulation in free-free and fixed
Electric vehicles (EVs) represent a pivotal shift in the automotive industry, offering a sustainable alternative to traditional gasoline-powered vehicles. Central to their operation are lithium-ion batteries, which are favoured for their high energy density and long lifespan. Ensuring thermal stability during battery pack operation is crucial for both safety and efficiency. To enhance heat transfer within the battery pack, various encapsulants are employed. This study utilizes simulation to investigate the thermal performance of a 3.072kWh, 51.2V, 60Ah battery pack composed of 6Ah 32700 LFP cells, encapsulated with commercially available materials such as polyurethane (PU) foam, silicone, and silicone-modified epoxy under 1C and 2C discharge conditions. The findings show that, at 1C and 2C discharge rates, respectively, the battery pack potted with silicone attains a maximum temperature that is 2.57°C and 3.84°C lower than the pack simulated with air. Additionally, silicone-modified
Since the inception of battery driven electric vehicles in the automotive world, there has been a constant challenge in maximizing the range of an electric vehicles through various means including battery technology, vehicle weight optimization, low drag coefficients etc. The tires being a viscoelastic composite material have now become a vital to the range performance of an EV. The rolling resistance of a tire is now become a hotter topic than ever. The rolling resistance coefficient (RRC) is the measure of energy loss during rolling due to viscoelastic dissipation in the tire. The viscous dissipation in tire arises due to hysteresis in the various components of a tire including tread, sidewall, inner liner, apex etc rubber compounds. The internal friction between layers of body ply, steel belts and tread crown ply also contribute to the internal heat generation. Therefore, the development of ultra-low RRC tires is a serious challenge for tire engineers. Nevertheless, the recent
A silicone membrane for wearable devices is more comfortable and breathable thanks to better-sized pores made with the help of citric acid crystals. The new preparation technique fabricates thin, silicone-based patches that rapidly wick water away from the skin. The technique could reduce the redness and itching caused by wearable biosensors that trap sweat beneath them. The technique was developed by bioengineer and professor Young-Ho Cho and his colleagues at KAIST and reported in the journal Scientific Reports.
This SAE Aerospace Information Report (AIR) summarizes data and background relative to age control of specific classes of those nitrile type synthetic elastomers used in sealing devices which are resistant to petroleum base hydraulic fluids, lubricating oils, and aircraft fuels. This includes, but is not limited to, those nitrile (NBR or BUNA-N) elastomers previously covered by Section I of MIL-STD-1523.
This specification covers a silicone (MQ/VMQ/PVMQ) elastomer that can be used to manufacture product in the form of sheet, strip, tubing, extrusions, and molded shapes. This specification should not be designated for use in molded O-rings and molded O-ring cord, molded rings, compression seals, molded-in-place gaskets, and plate seals for aeronautical and aerospace applications.
Anne-Marie Vincent Dow Silicones Belgium SRL Seneffe, Belgium
Recurring thermal loads in a vehicle can lead to the failure of rubber bearings due to thermal aging within the expected vehicle lifetime. The disadvantages of a preventive or reactive maintenance strategy are high warranty costs and low customer satisfaction, respectively. This work proposes a predictive maintenance system, which monitors the thermal aging of rubber bearings and indicates their timely replacement. Since no real temperature sensors are installed at rubber bearings in production vehicles, virtual temperature sensors are used to monitor component temperatures during customer operation. As a virtual sensor, a feedforward neural network is trained on measurement data in order to learn to predict the component temperatures of several rubber bearings in a combustion engine vehicle based on existing vehicle signals. The neural network achieves an average mean absolute error of 1.78 K and a coefficient of determination of 0.95 over all components after hyperparameter tuning
Elastomeric bushings are common components in vehicles, used to reduce noise, vibration, and harshness. Rubber bushings are employed in suspension components such as control arm bushings, subframe bushings, and motor mount bushings, each with varying static and dynamic stiffness requirements depending on vehicle weight and ride and handling performance. Traditional rubber bush simulations typically use simple material models like hyperelastic or viscoelastic models. However, recent advancements have introduced more sophisticated material models to capture the nonlinear and time-dependent behavior of rubber materials. These advanced models may incorporate nonlinear viscoelasticity, strain rate dependency, and damage mechanics. Rubber bushings experience multiple physical phenomena simultaneously, such as mechanical loading, thermal effects, and fluid-structure interaction. New simulation techniques enable the coupling of different physics domains, allowing for a comprehensive analysis
Silicone elastomers have become a vital material in the medical device industry due to their unique properties, including biocompatibility, durability and chemical inertness. Silicone materials are categorized based on their unvulcanized consistency, which significantly affects their processability and their physical properties. This article compares high consistency silicone rubbers (HCRs), liquid silicone rubbers (LSRs), and low consistency elastomers (LCEs), analyzing their characteristics and the implications in selecting each during different phases in the development of silicone medical devices.
This document establishes age limit and guidance for acceptance of hose and hose assemblies containing elastomeric materials for use in aircraft, space vehicles, missiles and component assemblies thereof at time of delivery to the contractor, procuring activity, or contracting officer. This document does not establish limitations on storage times for military/civil activities nor operating life.
This specification covers a fluorocarbon (FKM) rubber in the form of O-rings, O-ring cord, compression seals, and molded-in-place gaskets for aeronautical and aerospace applications.
This specification covers a fluorosilicone (FVMQ) elastomer that can be used to manufacture product in the form of sheet, strip, tubing, extrusions, and molded shapes. This specification should not be used for molded rings, compression seals, molded O-rings, molded O-ring cord, and molded-in-place gaskets for aeronautical and aerospace applications.
For engineers working on soft robotics or wearable devices, keeping things light is a constant challenge: heavier materials require more energy to move around, and — in the case of wearables or prostheses — cause discomfort. Elastomers are synthetic polymers that can be manufactured with a range of mechanical properties, from stiff to stretchy, making them a popular material for such applications. But manufacturing elastomers that can be shaped into complex 3D structures that go from rigid to rubbery has been unfeasible until now.
Innovators at NASA Johnson Space Center have developed a method using low-viscosity RTV silicone to form durable seals between polymer bladder and metal bulkhead interfaces to be used for inflatable space habitats.
A method of overall modeling and step-by-step solution was proposed to verify and analyze the strength of the mount shell. First, a reliable finite element simulation model was established based on testing of the mechanical properties of rubber materials, constitutive model construction, and stiffness tests of the mounts. Second, the displacement of the mount system under preloading and crash loads was calculated separately through the modeling of the powertrain mount simulation, which provided accurate load conditions of the mount for the following work. Finally, the strength calculation and evaluation of the mount shell was completed with the quasi-static solution method. This calculation method could consider the influence of complex factors comprehensively, such as assembly load distribution, large deformation of rubber, and contact nonlinearity on the stress distribution of the mount shell. In addition, the calculation method could solve the problem of balance between solution
This specification covers a fluorosilicone (FVMQ) elastomer that can be used to manufacture product in the form of sheet, strip, tubing, extrusions, and molded shapes. This specification should not be used for molded rings, compression seals, molded O-rings or molded O-ring cord, and molded in place gaskets for aeronautical and aerospace applications.
As aerospace engineers push the boundaries of new frontiers, the need for advanced materials that can withstand the rigorous demands of these advanced applications is relentless. These materials go beyond functionality; it is about ensuring reliability in the skies, where failure is not an option. Fluorosilicone can help do exactly that. In the 1960s, the U.S. Air Force noticed that conventional silicone-based sealants, coatings, and other components degraded rapidly when exposed to fuels, de-icing fluids, and other hydrocarbon-based solvents. Dimethyl-based silicones are non-polar and easily absorb hydrocarbon-based solvents, which may result in material swelling, mechanical weakening, and ultimately, failure.
Electric trucks and off-highway vehicles weigh about 30% more than their gasoline- and diesel-powered counterparts. That's a challenge for OEMs who want to reduce vehicle weight to increase range but are bound by the limits of current battery technology. To reduce vehicle weight, OEMs can make design changes in other areas, such as by replacing steel with thermoformed plastics, aluminum alloys and composite materials. What manufacturers may overlook, however, is the weight savings that can be achieved with industrial rubber products. Rubber is already lightweight, but there are heavier-than-necessary elastomeric components used throughout vehicle interiors and exteriors, typically with metal or plastic fasteners.
This specification covers polythioether rubber fuel-resistant sealing compounds supplied as a two-component system that cures at room temperature.
The present study discusses the determination of the Seal drag force in the application where an elastomeric seal is used with a metallic interface in the presence of different fluids. An analytical model was constructed to predict the seal drag force and an experimental test was performed to check the fidelity of the analytical model. A Design of Experiment (DoE) was utilized to perform an experimental test considering different factors affecting the Seal drag force. Statistical tools such as the Test for Equal Variances and One Way Analysis of Variance (ANOVA) were used to draw inferences for the population based on samples tested in the DoE test. It was observed that Glycol fluids lead to lubricant wash-off resulting in increased seal drag force. Additionally, non-lubricated seals tend to show higher seal drag force as compared to lubricated seals.
The global medical device market offers opportunities for innovation-driven growth. Demand for smart, new lifesaving and life-enhancing technologies is perhaps stronger than ever. Manufacturers around the world looking to capitalize on this eager global market face a long list of challenges — some big, some small. Supply-chain disruptions, labor shortages, rising materials costs, and other headwinds are leading to delays in both engineering and manufacturing processes. Despite these challenges, the world demands medical device manufacturers’ best. A surging geriatric population, implications of a global pandemic, and the mortality rates for heart disease, cancer, obesity, and other conditions are all contributing to strong and sustained market demand. One study predicts a compound annual growth (CAGR) of 5.4 percent will push global sales of medical devices to nearly $658 billion (USD) by 2028. Of course, the road to success will be littered with familiar roadblocks — and some that are
This specification covers an acrylonitrile-butadiene (NBR) elastomer that can be used to manufacture product in the form of sheet, strip, tubing, extrusions, and molded shapes. For molded rings, compression seals, O-ring cord, and molded-in-place gaskets for aeronautical and aerospace applications, use the AMS-P-83461 specification or the MIL-PRF-25732 specification.
This specification covers a silicone (MQ/VMQ) elastomer that can be used to manufacture product in the form of sheet, strip, tubing, extrusions, and molded shapes. This specification should not be used for molded rings, compression seals, molded O-ring cord, and molded-in-place gaskets for aeronautical and aerospace applications.
This study delves into the dynamic properties of hybrid composite materials, specifically focusing on the natural frequency and modal damping characteristics of Coir Fiber-Rubber Particles Reinforced Polymer Composites (CRP). Comprehensive experimental investigations were conducted utilizing an FFT analyzer. Initial experiments involved the preparation of specimens with varying rubber content, ranging from 2% to 5%. Coir, known for its cellulose-rich composition, was selected due to its innate damping properties, making it highly effective in mitigating vibrations. The primary motivation behind this research is to provide cost-effective solutions for reducing vibrations in mobility vehicles, addressing challenges associated with passenger comfort, durability, and overall performance. The study yielded promising results, with CRP exhibiting substantial reductions in vibrations. The findings of this research are expected to serve as valuable inputs for the design and engineering of
This paper investigates the tire-road interaction for tires equipped with two different solid rubber material definitions within a Finite Element Analysis virtual environment, ESI PAMCRASH. A Mixed Service Drive truck tire sized 315/80R22.5 is designed with two different solid rubber material definitions: a legacy hyperelastic solid Mooney-Rivlin material definition and an Ogden hyperelastic solid material definition. The popular Mooney-Rivlin is a material definition for solid rubber simulation that is not built with element elimination and is not easily applicable to thermal applications. The Ogden hyperelastic material definition for rubber simulations allows for element destruction. Therefore, it is of interest and more suited for designing a tire model with wear and thermal capabilities. Both the Mooney-Rivlin and Ogden-equipped Mixed Service Drive truck tires are subjected to a simulated static vertical stiffness test to validate their static domain characteristics against
Rubber isolators are widely used under random vibrations. In order to predict their fatigue life, a study on the fatigue analysis methodology for rubber isolators is carried out in this paper. Firstly, taking a mount used for isolating air conditioning compressor vibrations as studying example, accelerations versus time of rubber isolator at both sides are acquired for a car under different running conditions. The acceleration in time domain is transformed to frequency domain using the Fourier transform, and the acceleration power spectral density (PSD) is the obtained. Using the PSD as input, fatigue test is carried for the rubber isolator in different temperature and constant humidity conditions. A finite element model of the rubber isolator using ABAQUS is established for estimating fatigue life, and model validity is verified through static characteristic testing. Dynamic responses of the rubber isolator at frequency domain are calculated if a unit load is applied. The estimated
Compared to other age groups, older adults are at more significant risk of hip fracture when they fall. In addition to the higher risk of falls for the elderly, fear of falls can reduce this population’s outdoor activity. Various preventive solutions have been proposed to reduce the risk of hip fractures ranging from wearable hip protectors to indoor flooring systems. A previously developed rubberized asphalt mixture demonstrated the potential to reduce the risk of head injury. In the current study, the capability of the rubberized asphalt sample was evaluated for the risk of hip fracture for an average elderly male and an average elderly female. A previously developed human body model was positioned in a fall configuration that would give the highest impact forces toward regular asphalt. Three different rubber contents with 14, 28, 33 weight percent (% wt.) were implemented as the ground alongside one regular non-rubberized (0%) asphalt mixture, one baseline, and one extra-compliant
This specification provides requirements for the identification and packaging of sheet, strip, extrusions, and molded parts made of natural rubber, synthetic rubber, reclaimed rubber, and combinations of the above with other materials such as asbestos, cork, and fabrics. AMS2817 covers preferred requirements for identification and packaging of preformed packings.
For more than a century, pneumatic (air-inflated) tires have totally dominated the market for road vehicle tires. However, in the recent two decades, interest has grown in developing airless tires. Some of the authors were involved in design of an early version in composite material 15-30 years ago for passenger cars. Presently, the EU project LEON-T (Low particle Emissions and lOw Noise Tyres) includes a part in which prototypes for innovative heavy goods vehicle (HGV) tires are developed, with the main purpose to reduce noise emission by 6 dB. To reduce noise that much it is believed that airless tires are needed. A special challenge is to get a durable design able to carry typical truck tire loads. This paper introduces the principal design of airless tires. Airless tire prototypes are intended to be developed by partner Euroturbine, in cooperation with mainly Applus+ IDIADA, VTI and subcontractor Lightness by Design. The tire consists of a rim, load-carrying spokes, composite belt
The Indian passenger vehicle market has grown by more than 40% by volume in the last decade and has reached a record high in FY23. This has created a more diverse and demanding customer base that values interior design and quality. The modern customer expects a high level of aesthetics and sophistication in their vehicle interiors - including in the luggage area. The Luggage Cover (Parcel Tray) is a component in the luggage area of a passenger vehicle that is used to conceal the luggage & improve its aesthetics. The cover is generally made of thermoplastic material with rotating hinges and is held in its place by the compression from the back door, which is frequently opened and closed. The parts that connect the cover to the door (usually an elastomer interface on the thermoplastic tray) tend to change over a period due to climatic conditions and leads to rattling concerns over a period. The change in elastomer interface with the back door (due to repeated compression & climatic
The art of rubber formulation science always has a scope for fine-tuning with changing the parameters like base polymer grade selection, filler selection, curing system/cross link density, manufacturing methods, and many. Hence forth the filler manufacturer arrived differentiation of the filler already, this paper provides a description of rubber formulation tuning for damped vibration automotive applications. Acicular spiky spherical and hollow spherical nano silica selected as filler. With the thorough knowledge of elastomeric formulation and with doping different new selected silica grades, an optimized DOE was done. New formulation development was focused on isolation characteristics without affecting other necessary properties. The different inputs for finite element calculations was studied with the effects of doping different fillers and also studied the resultant virtual output in damping coefficients. Quad lap shear specimen was used as a standard part in which virtual and
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