Design of a dynamic tensile test rig

Abstract

This report presents the design process of a Split Hopkinson Tension Bar for fiber substance (Nylon, Poly-propylene rope). The setup will be built from scratch and tested for results. Due to the nature of the testing specimen, poly-methyl-methacrylate (PMMA) will be used as the material for the incident and transmitter bars respectively. The setup will be used to test the dynamic tensile strain for the fiber. The quarter-bridge three wire strain gauge configuration will be mounted at three different positions. One strain gauge is mounted on the incident bar, close to the clamped area while the other two will be mounted 200mm away from the specimen. Each Wheatstone quarter bridge is excited by a TML Dynamic Strainmeter. The signals are then fed into a Yokogawa DLM2024 mixed signal oscilloscope. The results are tabulated using Microsoft Excel spreadsheet and graphs are presented for the stress-strain curve, strain rate curve and finally the strain curve. The results show similar trend to what is produced in other literature reviews but however, due to the current device set-up, the inability to produce the instantaneous release of the stress wave produces sub-standard graphs and waveform. Suggestions for improvements were then introduced.