The paper describes a mathematical model of the stress-strain state of polymer composite materials in the pultrusion process of large-sized products. The influence of the pull speed on the stress-strain state of the products is investigated. To determine the maximum possible pull speed series of solutions at different pull speeds are obtained. Depending on the maximum strain in the cross section of the rod determined the optimal value of pulling speed.
Pultrusion is one of the most common ways to manufacture large products made of polymer composites. The possibilities to improve the performance of pultruded products depending on the reinforcement scheme are well studied [1-4]. The influence of constructive and technological parameters of pultrusion process on the properties of the resulting products is no less important. The most important to choose the optimal speed at which the quality product without the main cracks and discontinuity is received. The known mathematical models considered pultrusion process in the assumption that the polymerization of the resin is completed to the exit products from the die [5,6]. This assumption reduces the productivity of the process, making it unprofitable. A complex numerical model for evaluating stress-strain state of polymer composite material is developed. This model assumes incomplete polymerization process within the die. The relation between pull speed and stress-strain state of composite product at the exit from the die is investigated. As an example the optimum value of the pull speed is determined.
2. Statement of the Problem
Figure 1 shows the process of passing the composite material through a heated die. At the same time the polymerization process takes place. If the pull speed is high enough (>60 mm/min), then polymerization process of the oversized product does not have time to finish before it exits from the die. At this, the strain occurred in a polymerized part of the rod may exceed the maximum allowable values for the material which leads to the main crack appearance. The thermal stresses, the pressure of the liquid resin and chemical shrinkage are effects on the value of strain.
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