Strain rate effects on selected mechanical properties of glass-polyester laminates
Roman Gieleta, Paweł Gotowicki, Arkadiusz Popławski
Quarterly No. 2, 2013 pages 122-127
DOI:
keywords: layered composite, glass-polyester composite, high strain rate, SHPB
abstract The study presents the results of experimental testing of a layered cross-ply [0/90]n E-glass/polyester composite in the range of the selected compression properties at high strain rates = 2300÷4600 s-1 and a quasi-static strain rate = 0.0067 s-1. The composite was manufactured using contact technology using Owens Corning CD-600 E-glass stitched fabric and Polimal 104 polyester resin. The circular cross-section specimens of three sizes 2.5, 5 and 7.5 mm in height and 15 mm in diameter were tested in the above described experiments. To determine the static properties, quasi-static experimental tests were conducted using an Instron 8802 machine in the displacement control mode at a constant crosshead speed of 1, 2 and 3 mm/min respectively for the 2.5, 5.0 and 7.5 mm specimen types. The compression loading was monitored with a load cell Instron ±250 kN, whereas the axial strain with an Instron 2620-604 extensometer using additional fixing discs. The measuring base of the extensometer was equal to the specimen height. Identification included the stress-strain curve, strength, Young’s modulus and failure strain. For the high strain rates testing, a modified Split Hopkinson Pressure Bar test system was used, containing an LTT 500 Amplifier made by Tasler, Germany and an NI USB-6366 data acquisition device made by National Instruments, USA. The failure modes observed under high strain rate loading were similar to those observed under quasi static loading. The samples predominantly failed by shear fracture. Reduction of the specimen height implies an increase in the nonlinear effects in the initial part of the stress-strain diagrams (increasing strain at same stress), probably caused by the boundary effect. The main parts of the stress-strain plots are approximately linear, thus the linear elastic-brittle material model can be assumed. It was generally observed that the compressive strength and Young’s modulus along the thickness direction are higher at high strain rate loading compared to the results at quasi-static loading.