To support the manufacture of complex products made of multiple micro-parts, a traceable and accurate 3D-measurement system with sub-micron accuracy is required. This paper investigates the use of a micro electro mechanical system (MEMS) tactile-micro-probe for 3D-coordinate metrology on the micro-scale. It will show that probe-tip contamination may be a significant source of error for such tactile-probing systems. Even in a clean-room environment, there are many types of contaminants that may affect dimensional measurement accuracy. These mainly come from repeated contact between probe tip and artefact material. To address this issue a number of cleaning methods were utilized to remove contaminants from the MEMS tactile-micro-probe sensor. Scanning electron microscopy was used to assess the efficacy of each cleaning method. Initial findings on different cleaning methods including ultrasonic, plasma, micro-beam melting, electron beam melting and cryogenic cleaning have shown that the latter is a feasible process.
We investigate the fabrication of continuous carbon fiber/poly("-caprolactone) composites for biomedical applications. Two fabrication methods: in-situ polymerization and film stacking are compared at two different thicknesses. Analysis of void content produced via the two fabrication methods showed that the in-situ polymerization specimens had considerably lower void content than the film stacked samples. Significantly higher mechanical properties were obtained for the in-situ polymerized samples, and an almost three-fold increase in properties was seen as compared to the film stacked samples. Scanning electron microscopy images of surfaces supported the findings above. Dynamic mechanical analysis revealed higher dynamic modulus for the in-situ polymerized samples which was consistent with the above results.
In this study, a PLA matrix reinforced with phosphate-based glass fibres of the composition 40P 2 0 5 , 24MgO, 16CaO, 16Na 2 0, 4Fe 2 0 3 (Denoted P40) was investigated as a potential material for use in bone fracture fixation.Flexural studies (three point bending) were performed to investigate the mechanical properties of the composites produced. Single fibre fragmentation (SFFT) and interfacial shear strength (IFSS) were conducted to investigate fibrematrix properties.The degradation rate obtained for the glass formulation investigated in this study was 3x10~6 g.cm' 2 .h"'. The tensile strength and modulus value obtained for the fibres investigated was 309 MPa and 89 GPa respectively. IFSS values obtained in this study using the fragmentation test for untreated fibres was approximately 13 MPa, and for nondegraded APS and HEM A treated specimens were 14 and 19 MPa respectively. However surprisingly, for specimens degraded for up to 2 and 5 days the IFSS values increased to approximately 20+ MPa for the (1%) APS treated (which decreased to around 15 MPa after 7 days degradation) and to 31 and 33 MPa for the HEM A treated specimens respectively.The initial composite flexural strength and modulus obtained in this study were 91 MPa and 5 GPa respectively with a volume fraction (V f ) of between 13 and 17%. SEM analysis revealed no discernible differences between the nondegraded and 4 week degraded specimens. Composites produced using the HEMA and APS sizing agents retained their mechanical properties over the duration of the study.
In 3D tactile micro-metrology the contamination of probing devices is a major problem that affects the accuracy and repeatability of measured dimensions. Despite a large body of research in the field of micro CMM and micro probe design there is limited research which has been done so far to explain and tackle this problem. In this work, experimental probing on a range of materials using a micro coordinate measuring machine was conducted to investigate the mechanism of stylus tip contamination. In addition the effects of surface finish on the build-up of stylus tip contamination were also studied. The results provide practitioners with guidelines which allow for the likely build-up of stylus tip contamination to be minimized based on sample material type and surface finish.
Single-fiber fragmentation tests and degradation tests of carbon/poly("-caprolactone) composites were used to investigate the effect of two fabrication methods: in situ polymerization and film stacking. The resulting specimens were tested in the as-molded state and after time periods of up to 2 months in an aqueous environment. The results demonstrate considerably significant improvements in the flexural properties for samples from the in situ process compared with film stacking. This is attributed to superior wetting of the reinforcement. Single-fiber fragmentation tests confirm the superior interfacial shear strength from the in situ polymerized specimens.
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