In many industries, rubber components play a vital safety role in everyday activities. For this, rubber components need to be durable. Although in many cases, rubber components have many ways to fail during use, mechanical fatigue is probably the most common failure mechanism, affecting almost all rubber-related components. In the future, we will also explore solutions for other failure mechanisms, such as wear and chips, chemical erosion, expansion and inelastic failures.
When it comes to mechanical fatigue, we are concerned with the long-term performance and service life of rubber components subjected to repeated mechanical loading and unloading cycles. Conveyors, synchronous conveyor belts, different tire components, AV bases require repeated mechanical cycles when working.
The challenge often faced by composite developers is how to extend the fatigue life of components without affecting other performance, or how to improve dynamic performance without affecting the service life of components. Fortunately, in the face of such challenges, we have a rich and well-developed scientific framework to address them, as well as some basic material selection guidelines that can help us.
Deformation control mode
First, we need to understand the loop running conditions of the component. Is rubber deformation controlled by the cyclic load or displacement applied? This is crucial because it helps us adjust the stiffness of the complex to ensure that the storage capacity is minimized in the event of deflection where cracks may occur. For example, under deflection control, we can select a soft compound that minimizes the energy stored in the compound under deflection and inhibits crack propagation. Instead, for load control situations, we can harden the complex to minimize component deflection.
Choice of rubber
The selection of suitable rubber is the most important for mechanical fatigue properties. Natural rubber is an excellent choice for crack and tear resistant compounds. Its ability to crystallize under strain results in automatic strengthening of the crack tip. This mechanism prevents and passivates cracks during cyclic relaxation and non-relaxation deformation. Of course, natural rubber is not suitable for all applications. High temperature operations or chemically harsh conditions require the use of specific synthetic rubber. Compared with natural rubber, the strain crystallization properties of most synthetic rubber are not outstanding. In contrast, synthetic rubber relies entirely on particle strengthening operations to achieve the desired crack growth and tear resistance
Selection of reinforcing agent
Reinforcing agents, such as carbon black, play a crucial role in determining the crack growth and tear resistance of rubber components. The key is to choose the right load class, surface area and structural layer of carbon black. The selected carbon black needs to exhibit good dispersion properties and minimal physical impurities during the complex mixing process to achieve further improvement. The same factors need to be considered when selecting other granular preparations. Filler agglomerates and raw material impurities lead to an increase in the size and number of crack signs of the composite, both of which have adverse effects on fatigue life.
