Development of procedures for calculating stiffness and damping properties of elastomers in engineering applications. Part 4: Testing of elastomers under a rotating load

A test rig designed to measure stiffness and damping of elastomer cartridges under a rotating load excitation is described. The test rig employs rotating unbalance in a rotor which runs to 60,000 RPM as the excitation mechanism. A variable resonant mass is supported on elastomer elements and the dynamic characteristics are determined from measurements of input and output acceleration. Five different cartridges are considered: three of these are buttons cartridges having buttons located in pairs, with 120 between each pair. Two of the cartridges consist of 360 elastomer rings with rectangular cross-sections. Dynamic stiffness and damping are measured for each cartridge and compared with predictions at different frequencies and different strains

Tribute to Professor Ronald Harling Maudsley

A dedication to Professor Ronald Maudsley

Towards the development of a forensic DNA biosensor

In the forensic DNA field, quantitative PCR (qPCR) is commonly used to quantify the amount of deoxyribonucleic acid (DNA) in evidentiary samples. Though sensitive, this method is prone to error. Electrochemistry-based biosensors have been described as a possible alternative to qPCR. To this end, this work aims to develop a biosensor for forensic quantification by chemisorbing oligonucleotides functionalized to methylene blue onto the surface of gold screen-printed electrodes. Prior to this, the surface characteristics of the screen-printed gold electrode are examined through the use of a well-known redox probe Ru(NH3)62+/3+. Cyclic voltammetry (CV) and Square Wave voltammetry (SWV) were used to measure the current signal. The Randles-Sevčik equation was used to relate the area of the electrode with the current signal. Surface examinations of the gold screen-printed electrodes suggested these electrodes are suitable for use as a forensic DNA biosensor. Attempts to bind the oligonucleotide to the gold electrode were conducted. Though binding was successful, the resultant SWV signal suggested methods to chemisorb DNA onto gold surfaces require optimization

Development of procedures for calculating stiffness and damping of elastomers in engineering applications. Part 5: Elastomer performance limits and the design and test of an elastomer damper

Tests were performed on elastomer specimens of the material polybutadiene to determine the performance limitations imposed by strain, temperature, and frequency. Three specimens were tested: a shear specimen, a compression specimen, and a second compression specimen in which thermocouples were embedded in the elastomer buttons. Stiffness and damping were determined from all tests, and internal temperatures were recorded for the instrumented compression specimen. Measured results are presented together with comparisons between predictions of a thermo-viscoelastic analysis and the measured results. Dampers of polybutadiene and Viton were designed, built, and tested. Vibration measurements were made and sensitivity of vibration to change in unbalance was also determined. Values for log decrement were extracted from the synchronous response curves. Comparisons were made between measured sensitivity to unbalance and log decrement and predicted values for these quantities