Design Of Rubber Components Research Articles

Effect of vulcanization time on crosslink density and aging performance of natural rubber composites

Abstract Natural rubber composites are widely used in the automotive industry because of their improved viscoelastic characteristics that are mostly governed by crosslink density. However, rubber parts suffer deterioration of performance over long service lives. Therefore, optimization of crosslink density and prediction of changes in physico-mechanical properties over time at elevated temperatures is extremely important for the production of safe auto parts. In this work, the effect of vulcanization time on crosslink density and thus the performance and lifetime of natural rubberbased auto parts was investigated. The natural rubber mixture prepared in this context was vulcanized for 3, 5, 10 and 15 minutes at a constant temperature of 160 °C. The crosslink density of each vulcanizite was determined by equilibrium swelling tests and the Flory-Rehner equation. The maximum crosslink density (10.75 × 10-5 mol × cm-3) and the minimum permanent compression set values (10 % at 70 °C and 25 % at 100 °C) were recorded for the sample vulcanized for 10 minutes (v10). Aging behavior of the samples were investigated by stress relaxation tests performed at 85 °C, 100 °C and 120 °C. The service lives of the vulcanizites at different temperatures were predicted by linear Arrhenius fits of degradation times. The sample vulcanized for 10 minutes (v10) was shown to exhibit a service life of 2282 hours at 70 °C in air and the optimum physico-mechanical performance under real operating conditions. The performance and lifetime prediction procedure used in this work could be employed in an early design of rubber components for specific applications.

Effect of vulcanization time on crosslink density and aging performance of natural rubber composites

Abstract Natural rubber composites are widely used in the automotive industry because of their improved viscoelastic characteristics that are mostly governed by crosslink density. However, rubber parts suffer deterioration of performance over long service lives. Therefore, optimization of crosslink density and prediction of changes in physico-mechanical properties over time at elevated temperatures is extremely important for the production of safe auto parts. In this work, the effect of vulcanization time on crosslink density and thus the performance and lifetime of natural rubberbased auto parts was investigated. The natural rubber mixture prepared in this context was vulcanized for 3, 5, 10 and 15 minutes at a constant temperature of 160 °C. The crosslink density of each vulcanizite was determined by equilibrium swelling tests and the Flory-Rehner equation. The maximum crosslink density (10.75 × 10-5 mol × cm-3) and the minimum permanent compression set values (10 % at 70 °C and 25 % at 100 °C) were recorded for the sample vulcanized for 10 minutes (v10). Aging behavior of the samples were investigated by stress relaxation tests performed at 85 °C, 100 °C and 120 °C. The service lives of the vulcanizites at different temperatures were predicted by linear Arrhenius fits of degradation times. The sample vulcanized for 10 minutes (v10) was shown to exhibit a service life of 2282 hours at 70 °C in air and the optimum physico-mechanical performance under real operating conditions. The performance and lifetime prediction procedure used in this work could be employed in an early design of rubber components for specific applications.

Fatigue Life Evaluation of Rubber-Clay Nanocomposites

The interest of fatigue life evaluation for rubber component such as engine mount was increasing according to the extension of warranty period of the automotive components. A design of rubber components against fatigue failure is one of the critical issues to prevent the failures during the operation. Therefore, fatigue life prediction and evaluation are the key technologies to assure the safety and reliability of mechanical rubber components. In this study, we developed rubber material that is environment-friendly and superior in physical property and fatigue life using rubber-clay nanocomposite. We performed static and dynamic tests of rubber-clay nanocomposite synthesized by inserting nano-filler between silicate layers at the high temperature of +70 ˜+100°C, and verified that their mechanical properties were superior to the existing rubber material. In addition, a new method was developed to estimate fatigue lifetime of rubber parts in a short period in the initial stage of design, assuming that the fatigue damage parameter was Green-Lagrange strain generated at the weak points of parts. As results of estimation of fatigue durability, it was verified that the fatigue lifetime obtained by fatigue tests on actual engine mounts and the expected lifetime relatively match. With the results of finite element analysis of rubber parts using the fatigue lifetime estimation method suggested in this study, the lifetime can be estimated without fatigue tests on rubber parts. Therefore, we can save development time and expense and achieve good quality and reliability of rubber parts.

Finite Element Analysis by Using Hyper-Elastic Properties for Rubber Component

The material modeling of hyper-elastic properties in rubber is generally characterized by the strain energy function. The strain energy functions have been represented either in term of the strain in variants that are functions of the stretch ratios, or directly in terms of the principal stretch. Successful modeling and design of rubber components relies on both the selection of an appropriate strain energy function and an accurate determination of material constants in the function. Material constants in the strain energy functions can be determined from the curve fitting of experimental stress-strain data. The uniaxial tension, equi-biaxial tension and pure shear test were performed to acquire the constants of the strain energy functions which were Mooney-Rivlin and Ogden model. Nonlinear finite element analysis was executed to evaluate the behavior of deformation and strain distribute by using the commercial finite element code. Also, the fatigue tests were carried out to obtain the fatigue failure. Fatigue failure was initiated at the critical location was observed during the fatigue test of rubber component, which was the same result predicted by the finite element analysis.

The Mounting of Aero Engines with Special Reference to Rubber and Buna Material

The following remarks refer to the fundamental conditions which have to be considered for the use of rubber for the mounting of engines. It is thought essential that aircraft firms should ask for information with regard to rubber components they intend to use at an early stage of the design so that faulty applications of such parts can be prevented. Figures for the permissible loads and hints for the design of rubber components are given, with special reference to the use of Buna. Some constructional features are discussed as an explanation of the advice tendered to the designer.