Impact characterization of a carbon fiber‐epoxy laminate using a nonconservative model

Abstract

ABSTRACT:The study of polymer and composite behavior under high strain rates is of fundamental relevance to determine the material suitability for a selected application. However, the impact phenomenon is a very complicated event, mainly due to the short duration, large deformation, and high stresses developed in the sample. In this work, we have performed impact tests over a carbon fiber reinforced epoxy using low-energy in the striker. A nonconservative and nonlineal spring-dashpot series model has been proposed to reproduce the material behavior. The model considers simultaneously both flexural and indentation phenomena accounting for energy losses by means of the restitution coefficient. Using this model, an excellent fit between the predicted and the experimental force-time trace has been obtained below the composite failure point, which was recognized by a separation of both mentioned curves. As the epoxy-fiber laminate has a very low viscoelasticity, the high strain rate Young's modulus obtained from the model was compared with that extracted from a conventional three point bending test, finding a very good match between the values. The study of the dashpot coefficients allows concluding that the dominant mechanism is the composite flexion, while the indentation effects contribution takes on importance at low impact velocities.

Effects of vacuum infusion processing parameters on the impact behavior of carbon fiber reinforced cyclic butylene terephthalate composites

“…At the subcritical impact tests (Figure 5(a) and (b)), 0.3 J impact energy (E 0 ) curves show an asymmetric round shape, which reveals that even at this low energy impact energy losses are significant. 24 Both contact time duration (t c ) and peak force (F p ) are practically the same for the composites of CF-pCBT(SC) and CF-pCBT(LC), so at this energy level stiffness and absorbed energy (E a ) are similar for the two composites.…”

Effect of the thermoforming process variables on the sheet friction coefficient

“…The four evaluated parameters were the following: material of the plug (aluminum and steel), temperature of the polymeric sheet, velocity of the mobile device displacement (equivalent to the velocity of plug's penetration), and superficial finishing of the plug. [19,20], although there is no clear reason for this behavior. The limited number of points is due to a less control of the heating device (infrared lamp).…”

“…Therefore, the inelasticity phenomenon shall be included in its experimental analysis. For this reason, the initial kinetic energy of the mobile device was overvalued, because there were considerable energy losses during the collision [18,19].…”

“…Sanchez-soto et al [18] and Martínez et al [19] in a previous work suggested alternative methods to calculate e using the collision impact technique by fall in order to quantify the impact energy loss between the two materials incorporating e.…”

“…Although some studies [9,19] showed the influence of the penetration velocity of the plug in the plug-sheet l d , it shall be considered that in the typical thermoforming processes, the range in which penetration velocities may vary is relatively small. Such velocities are produced by the plug displacement.…”