# Experimental Research of Rubber Composites Subjected to Impact Loading
## Materials and Methods  
### Experimental Material  
The experiments were carried out with rubber composites used for the transport of materials on belt conveyors. The cover layers of conveyor belts are intended to protect the fabric or steel-cord carcass against mechanical damage and corrosion. Cover layers of belts must meet the following requirements [23]: high abrasive resistance; good elasticity; high strength; and increased resistance to ageing, ozone and fatigue. The cover layer thickness should be chosen on the basis of the type and properties of the transported material, its nature (pieces or bulk), weight, sharpness of edges, degree of abrasive effects, impact energy, drop height of the transported material, method of filling a conveyor, etc. The conveyor belt carcass's role is to transfer tensile forces from the driving pulley to the belt itself; it also provides the required strength and puncture resistance of the conveyor belt. The top cover layer and the protective edge enclose the carcass and protect it against mechanical damage caused by the transported material, against the effects of humidity and against chemical and thermal effects to which the conveyor belt is exposed. The bottom cover layer comes into contact with conveyor pulleys and protects the carcass against their negative effects. An important factor is the adhesion of the cover layer to the carcass, as it facilitates the transmission of torque of the driving pulley to the entire conveyor belt [24]. The carcass of the conveyor belt comprises a ply, which may be fabric or steel, and its individual components are connected using an elastic material. The carcass of fabric conveyor belts consists of one or more fabric piles (Figure 1). The plies are impregnated and rubber-coated fabrics possessing required mechanical and physical properties. Typically, the carcass of the conveyor belt also comprises a bumper, which increases the puncture resistance of the belt. Such belts are used in the technology for surface mining, quarries and transport of heavy large-piece materials. The bumper is made of polyamide, polyester, steel cord or aramid. These belts exhibit higher resistance to the development and propagation of punctures caused by the falling material at improper drop heights. In the case of steel-cord conveyor belts, the carcass consists of steel cords in the core rubber. The carcass of fabric belts is made of natural or synthetic fibres with properties that determine their applications. Currently used types of fibres may be divided into the following groups based on various criteria, the most common one being their origin [23]:  
* Natural fibres--made of natural macromolecular substances of animal or herbal origin and mineral substances; the fibres are produced mechanically (e.g., cotton);
* Chemical fibres--made of natural or synthetic polymers in a chemical process (e.g., polyamide, polyester, aramid);
* Metallurgical fibres--made of inorganic substances in a metallurgical process (e.g., steel or glass). Tensile properties of conveyor belts depend on the carcass material. In the case of fabric belts, the carcass consists of several layers of fabric plies. The fabric plies are produced by crossing warps and wefts. A warp is a set of threads in the longitudinal direction, and a weft is a set of threads in the transversal direction. Such a fabric structure directly determines the tensile properties of the belt itself. In order to improve these properties, a combination of different fabrics in warps and wefts is sometimes used. In EP-type conveyor belts, it is a combination of polyester fabrics in the warp and polyamide fabrics in the weft. Such structure exhibits good resistance to dynamic fatigue and protects the belt against the development and propagation of punctures [26]. Experimental testing was carried out using the specimens (1200 \(\times\) 150 mm) of fabric conveyor belts of the P 2000/4 8 + 4 201A type.