Mechanical properties of polymer composites produced by resin injection molding for applications under increased demands for quality and repeatability

Abstract

The paper analyzes the effect of the cutting angle on the mechanical properties of a fiber composite cut with a water jet cutter applying different speeds. Unlike plasma or laser processing, water jet cutting is a high precision method with no toxic emissions or waste production. The experiments were conducted for a glass reinforced resin matrix composite produced with the Resin Infusion Molding method. The polymer matrix (Polimal 109-32K resin) was reinforced with a two-directional glass fabric (Saertex) with fibers intersecting at an angle of ±45°. The highest efficiency of the 3-dimensional water jet cutting process was reported at the angle of 45^°. The composite samples cut with a velocity of 3,000m/s exhibited more stable properties than those cut with velocities of 5,000 and 10,000m/s. The mechanical properties of the material were assessed assuming that there were two layers, each with different physical and mechanical properties, which resulted from different fiber arrangements. 
The strength of the composite was analyzed using samples cut with different cutting speeds. It was necessary to determine which layer would fail first. The strength was forecast basing on the distribution of stresses in each layer. It was important to establish the influence of the number and thickness of layers on the mechanical properties of the composite. By calculating the strength of the laminate, it was possible to determine the deformations, loads and residual stresses in each layer as well as the total stress responsible for the material failure.