Experimental and Theoretical Analysis of Pulling Force in Pultrusion and Resin Injection Pultrusion (RIP)–Part I: Experimental

Abstract

Pulling force is the summation of resistance forces along a pultrusion die. Its mechanism is complicated because the impregnated resin inside the compressed fiber reinforcement changes from a liquid to a gel, and finally to a solid in the die. Two methods, a ‘mat tracer’method and a ‘short die length’ method, were used to determine the pulling force distribution. Results show that the downstream part of the die contributes little to the pulling force. In order to predict the resistance force in both the injection die and the heating die, two models were developed in this study. A friction measurement device was designed to measure the friction coefficient between the composite and the mold surface. The effect of process variables, such as temperature, resin conversion, normal force, and line speed, on the friction coefficient was investigated and a friction coefficient model was proposed based on the experimental results. A volume change model of vinylester resin was also developed to predict the thermal expansion–polymerization shrinkage during curing. The parameters of the model were determined by dilatometry, thermomechanical analysis (TMA) and differential scanning calorimetry (DSC).

Polymer Composite Manufacturing Using a Pultrusion Process: A Review

“…Jeswani et al (2009) also revealed that the increase of pulling speed improved the properties of the pultruded profile. Li et al (2003) implemented mat tracer method and short die length method in studying the effect of die length on the pulling speed in pultrusion process. The increase of the die length does not affect the pulling force.…”

Computational Approaches for Modeling the Multiphysics in Pultrusion Process

“…Pull Force Model. As aforementioned, four different contributions to the overall pulling force in pultrusion have been identified in the literature [2,3,[14][15][16][17][18][19][20][21]: the collimation force col , the bulk compaction force bulk , the viscous drag vis , and the frictional force fric . These contributions are strictly related to the geometrical features of the die-work piece system and to the resin transitions from liquid to gel and then solid status, as schematized in Figure 3.…”

“…It should be noted that the value of the friction coefficient depends on the DOC during the resin gelation and further varies at the glass transition. However, due to the lack of thorough experimental data, generally the averaged values are utilized [14][15][16][17][18][19][20][21]. Regarding the magnitude of the contact pressure, is considered to be affected by two contrasting conditions: the transverse thermal expansion of the composite due to the increase in temperature and pressure and the resin chemical shrinkage related to crosslinking reaction.…”

“…The total displacement Δ = ΣΔ , and the virtual radius V can be evaluated by extending equation (21) to the whole radius. In particular, from the die inlet until the detachment point, due to the prevalence of the thermal expansion on the chemical shrinkage, the virtual section of the processing composite results reasonably greater than the die cavity.…”

“…The aforementioned features, in turn, depend on the pull speed, die temperature, die geometry, constituents' type, and volume fractions. Furthermore, the pulling force consists of different contributions, such as the bulk compaction force due to the pressure increase in the tapered portion of the die, the viscous drag acting in the liquid zone, and the frictional force due to the contact between the internal surface of the die and the solidified processing material [2,3,[18][19][20][21]. Experimental outcomes reported in [14] by Price and Cupschalk showed the impact of the materials volume fractions, die temperature and pull speed on the pull force.…”