Relaxation and creep behaviour of false banana’s fibre (Ensete ventricosum)
¹,²Czech University of Life Sciences Prague, Faculty of Engineering, Department of Mechanical Engineering, Kamýcká 129, CZ 165 21 Praha 6 Suchdol, Czech Republic
³Czech University of Life Sciences Prague, Faculty of Engineering, Department of Material Science and Manufacturing Technology, Kamýcká 129, CZ 165 21 Praha 6 Suchdol, Czech Republic
This study was focused on the analysis of viscoelastic behaviour of fibres of false banana (Ensete ventricosum). The aim of the experiment was to describe the short term creep and relaxation behaviour under tension loading. The fibers of Ensete ventricosum, originally from Ethiopian region Hawasa, were used in this experiment. Moisture content Mc = 8.40 ± 0.67% (d. b.) and true density ρt = 668 ± 44 kg m-3 of the samples were determined. The specimens had initial gauge length of L0 = 100 ± 1 mm and the average yarn breaking load (YBL) after 20 tests was σr = 14.3 ± 1.7 N. To determine the relationship between tension force and deformation, tension device (Labortech, MPTest 5.050, Czech Republic) was used to record the course of deformation function. All tests were performed using a constant rate α = 3.1 N s-1. The short term creep tests were performed using constant loads of 30%, 60% and 90% of the average YBL. The short term relaxation tests were performed using constant strain of 30%, 60% and 90% of maximal strain. Measured data were analysed by computer software Mathcad 14. Experimental reep and stress relaxation curves at different load levels were determined. Experimental creep lifetimes tr for different load levels: 24,311 ± 7,489 s (30% YBL), 1,831 ± 462 s (60% YBL) and 17.6 ± 5.5 s (90% YBL) were determined. Initial modulus of elasticity, finite modulus of elasticity and initial energy of stress relaxation and creep of Ensete fibres were determined.