Puncture characterization of rubber membranes

Puncture resistance is among the major mechanical properties of rubber membranes, yet the intrinsic material parameters controlling the puncture of these materials are still unknown. To evaluate puncture resistance, the ASTM F1342 standard test is currently the most commonly used method. Using a conical puncture probe, this test is designed for any type of protective clothing, including coated fabrics, laminates, textiles, plastics, elastomeric films or flexible materials. This work aims to investigate the quantitative material parameters that control the puncture resistance of thin rubber membranes. Three commercial rubbers commonly used in protective gloves are investigated. The results demonstrate that the probe-tip geometry strongly affects the results in puncture characterization. The maximum puncture force depends on the contact surface between the elastomer membrane and the probe tip. The indentation force has been calculated for elastomer membranes with large deformations in the absence of friction, using the Mooney strain-energy function. The puncture strengths of elastomer membranes are much lower than their tensile and biaxial strengths. The puncture of rubber membranes is controlled by a maximum local deformation that is independent of the indentor geometry.     

Sensitivity analysis of tire-ice friction coefficient as affected by tire rubber compound properties

Previous studies show that the material properties of the rubber are among the most important factors when designing a tire. In this study, we investigated the effects of different rubber properties on tire performance on ice. A theoretical model that incorporates these tire material properties was developed. The model was used to estimate the height of the water film generated due to friction and the friction coefficient for both, dry and wet regions at the tire-ice contact patch. After validating the results using experimentally collected data, the model was used to perform a sensitivity analysis on the tire performance with respect to six material properties of the tread rubber: thermal conductivity, rubber density, Young’s modulus, specific heat, roughness parameter of the rubber, and radii of spherical asperities of the rubber. To study the effect of each parameter, the desired material property was varied within a specific range while the other parameters were kept constant. The results from this study show the sensitivity of the magnitude of the friction coefficient to the rubber material properties. The friction coefficient has a direct relationship with the density of the rubber and has an inverse relationship with Young’s modulus, specific heat, and roughness parameter.     

Tire-ice model development for the simulation of rubber compounds effect on tire performance

The material properties of the rubber compounds, which are highly dependent on temperature, have a vital role in the tire behavior. A comprehensive study on the effect of the rubber properties on tire performance, for different temperatures, as well as different road conditions is required to adequately predict the performance of tires on ice.In this study, a theoretical model has been developed for the tire-ice interaction. The temperature changes obtained from the model are used to calculate the height of the water film created by the heat generated due to the friction force. Next, the viscous friction coefficient at the contact patch is obtained. By using the thermal balance equation at the contact patch, the dry friction is obtained. Knowing the friction coefficients for the dry and wet regions, the equivalent friction coefficient is calculated. The model has been validated using experimental results for three similar tires with different rubber compounds properties. The model developed can be used to predict the temperature changes at the contact patch, the tire friction force, the areas of wet and dry regions, the height of the water film for different ice temperatures, different normal load, etc.     

Synthesis and characterization of NaA zeolite particle as intumescent fiame retardant in chloroprene rubber system

NaA zeolite with average particle size of 1 m was successfully synthesized by microwave heating. Inu-ences of pre-crystallization time,microwave power and microwave heating time on the synthesis of NaA zeolite were investigated. The as-synthesized sample was characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM) and particle size distribution(PSD) . Thermal and fiame retardant properties as intumescent fiame retardant(IFR) in chloroprene rubber(CR) system,such as thermo-gravimetry(TG),lim...     

Statistical approach for a hyper-visco-plastic model for filled rubber: Experimental characterization and numerical modeling

This paper presents a campaign of experimental tests performed on a silicone elastomer filled with silica particles. These tests were conducted under controlled temperatures (ranging from ?55 °C to +70 °C) and under uniaxial tension and in shearing modes. In these two classes of tests, the specimens were subjected to cyclic loading at various deformation rates and amplitudes and relaxation tests at various levels of deformation. A statistical hyper-visco-elasto-plastic model is then presented, which covers a wide loading frequency spectrum and requires indentifying only a few characteristic parameters. The method used to identify these parameters consists in performing several successive partial identifications with a view to reducing the coupling effects between the parameters. Lastly, comparisons between modeling predictions and the experimental data recorded under harmonic loading, confirm the accuracy of the model in a relatively wide frequency range and a large range of deformations.     

Terrain classification using intelligent tire

A wheeled ground robot was designed and built for better understanding of the challenges involved in utilization of accelerometer-based intelligent tires for mobility improvements. Since robot traction forces depend on the surface type and the friction associated with the tire-road interaction, the measured acceleration signals were used for terrain classification and surface characterization. To accomplish this, the robot was instrumented with appropriate sensors (a tri-axial accelerometer attached to the tire innerliner, a single axis accelerometer attached to the robot chassis and wheel speed sensors) and a data acquisition system. Wheel slip was measured accurately using encoders attached to driven and non-driven wheels. A fuzzy logic algorithm was developed and used for terrain classification. This algorithm uses the power of the acceleration signal and wheel slip ratio as inputs and classifies all different surfaces into four main categories; asphalt, concrete, grass, and sand. The performance of the algorithm was evaluated using experimental data and good agreements were observed between the surface types and estimated ones.     

Rupture of rubber

Summary The theory of the tearing of rubber has been further confirmed by experiments on three test pieces of widely different shapes, for each of which the tearing energy can be calculated. This rupture concept has been used to interpret measurements of out growth under conditions of both static and dynamic loading.

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Zusammenfassung Die Theorie des Reißens von Gummi wird durch Versuche an drei Proben von wesentlich verschiedener Gestalt, für die jeweils eine Reiß-Energie berechnet werden kann, weiter erhärtet. Diese Vorstellung über den Bruchvorgang wird dazu verwendet, Meßergebnisse bezüglich des Einschnittwachstums (Rißvergrößerung) sowohl bei statischer als auch bei dynamischer Versuchsführung zu interpretieren.

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Presented at a meeting on Flow, Fatigue, and Failure held in Leeds on January 8th and 9th, 1959, by the British Society of Rheology.     

Finite element modeling of tire/terrain interaction: Application to predicting soil compaction and tire mobility

Tire/terrain interaction has been an important research topic in terramechanics. For off-road vehicle design, good tire mobility and little compaction on terrain are always strongly desired. These two issues were always investigated based on empirical approaches or testing methods. Finite element modeling of tire/terrain interaction seems a good approach, but the capability of the finite element has not well demonstrated. In this paper, the fundamental formulations on modeling soil compaction and tire mobility issues are further introduced. The Drucker-Prager/Cap model implemented in ABAQUS is used to model the soil compaction. A user subroutine for finite strain hyperelasticity model is developed to model nearly incompressible rubber material for tire. In order to predict transient spatial density, large deformation finite element formulation is used to capture the configuration change, which combines with soil elastoplastic model to calculate the transient spatial density due to tire compaction on terrain. Representative simulations are provided to demonstrate how the tire/terrain interaction model can be used to predict soil compaction and tire mobility in the field of terramechanics.     

磨损加疲劳载荷下的协同疲劳行为

自行研制的摩擦磨损装置与轴向疲劳试验机相互配合,实现GDL-1钢试样在疲劳应力(240~280 MPa)及接触载荷(30 N)作用下摩擦磨损疲劳试验.通过对磨损层厚度的分析,研究试样承受摩擦磨损载荷及拉压疲劳载荷双重作用下的疲劳寿命变化,用SEM扫描电镜观察分析次表层内疲劳裂纹扩展的演变过程,并采用Hertz线弹性理论和Smith接触理论计算分析摩擦表面以下切应力值.结果表明:在磨损疲劳载荷作用下,形变层的流变作用将显著影响疲劳小裂纹扩展方向,渐趋于切应力方向,从而提高试样疲劳寿命.在此基础上,建立了在摩擦磨损疲劳载荷下疲劳裂纹扩展模型.此外,计算可知在距表层深度0.03 mm处切应力最大,0.18 mm以内材料产生塑性变形,导致形变层的形成.     

Applied mechanics of rubber

International Applied Mechanics -     

Analytical model of longitudinal tire traction in snow

An analytical model to estimate longitudinal traction of a tire in snow was developed and verified to have good predictability in comparison with measurements. Snow traction of a tire is composed of four kinds of forces in this model: braking force attributable to snow compression, shear force of snow in void (space between tread blocks), frictional force, and digging force (edge effect generated by sipes and blocks). The mechanical characteristics of snow were considered in the prediction of braking force and shear force, but were not considered in the prediction of other forces. The contribution of shear force of snow in void and the frictional force was large in static traction (traction just before a tire slips). On the other hand, the contributions of digging force and frictional force were large in situations involving high slip ratios.     

An analytic model of a rolling pneumatic tire

The contact interaction of a pneumatic tire with a roadbed is studied. The discrepancy between the Gim-Nikravesh analytic model and experimental data is established to be due to the one-dimensionality of the model and the assumption that the pressure of the wheel on the roadbed is symmetric __________ Translated from Prikladnaya Mekhanika, Vol. 42, No. 4, pp. 128–135, April 2006.     

Modified Boussinesq''s equations for nonuniform tire loading

Hypotheses from elasticity theory were used for modeling stress distribution in a semi-infinite-homogeneous medium when a point load was applied on its surface. A Concentration factor coefficient was introduced to adapt the equations to the characteristics of the investigated soil. An expression for continuous load distributions and variations in the geometry of the contact area between soil and tire were obtained by means of the superposition principle. Some simulations for different areas and load distributions are discussed and compared with field measurements.     

Numerical investigation of hydroplaning characteristics of three-dimensional patterned tire

Hydroplaning characteristics of patterned tire on wet road are investigated by making use of finite volume and finite element methods. A detailed 3-D patterned tire model is constructed by our in-house modeling program and the rainwater flow is considered as incompressible and inviscid. Meanwhile, the fluid–structure interaction between the highly complicated tire tread and the rainwater flow is effectively treated by the general coupling method. Through the numerical experiments, the rainwater flow drained through tire grooves, hydrodynamic pressure and contact force are investigated and compared with those of the three-grooved tire model.