Journal Article

Modification of Charpy machine for the acquisition of stress-strain curve in thermoplastics

Zabala Gualtero, Luis Miguel, Figueroa López, Ulises, Guevara Morales, Andrea, Rojo Valerio, Alejandro

2020

Overview

Simulations of impact events in the automotive industry are now common practice. Vehicle crashworthiness simulations on plastic components cover a wide range of strain rates from 0.01 to 500 s-1. Because plastics mechanical properties are very dependent on strain rate, developing experimental methods for generating stress-strain curves at this strain rate range is of great technological importance. In this paper, a modified Charpy machine capable of acquiring useful information to obtain the stress-strain curve is presented. Strain rates between 300 to 400 s-1 were achieved. Three thermoplastics were tested: high-density polyethylene, polypropylene-copolymer and polypropylene-homopolymer. Impact simulations using LS-DYNA were performed using the acquired high-strain rates stress-strain curves and compared with experimental data. Simulations using stress-strain curves from quasi-static tests were also performed for comparison. Very good agreement between the simulation and experimental results was found when the ASTM D1822 type S specimen was used for testing each material.

• Publisher: Universidad Nacional de Colombia
• Subject: Automobile industry / computational simulation LS / computational simulation LS-DYNA / Crashworthiness / Deformation / DYNA / equipo de pruebas de impacto / Experimental methods / High density polyethylenes / Impact strength / impact testing equipment / Mechanical properties / Polyethylene / Polymers / Polypropylene / propiedades mecánicas / simulación computacional en LS / Simulation / Static tests / Strain / Strain rate / Stress-strain curves / Stress-strain relationships / tension / tension-impact testing equipment / tensión / termoplásticos / Thermoplastic resins / thermoplastics