Browsing by Author "Rose, Timothy"

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    Experimental and numerical investigation of heave damper hydraulic seal for racing car
    (Elsevier, 2022-06-29) Azar, Michel; Grasso, Marzio; Rose, Timothy; Carless, Owen; St Leger-Harris, Chris; Lawson, Carl
    This article presents a combined experimental and numerical approach to analyse the failure of a heave damper hydraulic seal for racing car. The post-mortem analysis of the damaged seals was carried out with both optical microscopy and finite element analysis using material test data from Dynamic Modulus Analyser (DMA). The stress in the seal and damper was simulated modelling each step including the press-fitting on the piston, the interference with the cylinder and the oil pressure due to the service. The combination of the evidence collected from the numerical simulation and the observation of the surface damages on the seals proved that the cause of failure was the insufficient lubrication during high frequency, short stroke applications since these working conditions induce oil film break. The detailed damage mechanisms have been identified and explained and an alternative seal design that requires further study and testing in this application has been proposed.
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    A new preparation method for 3D bio-composite filament manufacturing: a study on the effects of ball milling on the cohesion/adhesion of an agave tequilana bagasse/PLA pellet mixture
    (Springer, 2022-12-20) Salignon, Mathias; Gray, Simon; Rose, Timothy; Encinas-Oropesa, Adriana
    This study created a composite polymer for 3D printing from agave by-product using mechanical alloying process. The cold milling technique used by the ball mill is a standard procedure to homogenize metallic mixtures. This paper reports results from a series of laboratory tests to create a homogeneous mixture that could be extruded into a printable filament mixture of agave bagasse fibres and PLA pellets by using the kinetic energy of a ball mill. PLA and agave bagasse mixtures in this study were ground several times using this principle; steel and ceramic balls were used to grind them. The results of the study showed that this principle can be effective on a polymer-based mixture; indeed, an adhesion between the pellets and the agave bagasse fibres was obtained. The results showed the different parameters that influence the mixture quality as the milling time, the ball material, the number of balls, the mixture concentration and the rotational speed. Optical and ESEM/EDX analyses have confirmed our expectations about cohesion between fibres pulverized in powder and pellet adhesion, where powder accumulation on all the surfaces was detected. The absence of powder penetration in the pellets allowed us to explain the losses obtained during the process and to find new solutions to reduce them. Proof-of-concept parts were 3D printed with agave bagasse/PLA filaments. Their printed quality can be compared to that of commercial filaments. These results offer new perspectives to reuse agricultural by-products to create composite filament with a chemical-free manufacturing process.