The presence of weldline in rubber products is regarded as a one of the most undesirable phenomena, since it result in poor mechanical properties. Designers typically minimize the influence of weldlines by their placement in non-critical areas and the application of a factor of safety based on design specifications and anticipated failure modes. Such practice results in over-design of parts, since the factor of safety is generally independent of the material. Truly cost-effective part design

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... uires a better understanding of the behavior of polymers under different loads and failure conditions. A large amount of literatures have been published in regard to the effects of weldlines on the static mechanical properties of thermoplastics and thermoplastic composites. In the present study, the effect of weldline on the fatigue life of natural rubber was first investigated with regarding to the filler types and contents. The use of design data which takes into account the weldline formation as well as the filler loading will enable design engineers to more accurately predict the performance of rubber molded part under fluctuating load.