Loughborough University
Browse
Thesis-2005-Saleh.pdf (51.77 MB)

Effects of humidity and ageing on epoxy-based stereolithography materials

Download (51.77 MB)
thesis
posted on 2015-01-09, 11:26 authored by Naguib Saleh
In recent years, the use of Stereo lithography (SL) to produce end-use parts has increased rapidly. However, only limited applications have been considered as there are several problems that impede the conversion of Stereolithography to be used as a mainstream manufacturing process. One of the major problems is the instability of the SL parts post-build when subjected to environmental factors. This research included long-term material testing to investigate the effects of ageing, humidity and temperature on the mechanical properties of the SL parts. This work was carried out at a temperature range of -40°C to +lOO°C over differing ageing and humidity conditions (dry (lO%RH), controlled (SO%RH) and wet (lOO%RH». The results indicated that the main degradation factor was humidity. It was therefore selected for further investigation in this research. This is the most comprehensive analysis and characterisation of materials data yet compiled for additively manufactured materials. Stereolithography materials tested have been shown to significantly degrade over time when subjected to a high level of relative humidity. Therefore, it was the primary aim of this research to identify the mechanism of hygroscopic degradation of Epoxy-based SL materials. This was achieved using various techniques including mechanical tests, Differential Scanning Calorimetry (DSC) and Attenuated Total Reflectance (ATR). Modelling of water penetration into SL Epoxy-based parts was undertaken and the type of diffusion was found to be anomalous (non-Fickian). Therefore a dualFickian model was developed to identify the diffusion coefficients of the investigated materials. Additional equations were developed to model the profiles of moisture concentration and Young's Modulus within a specimen and to predict the stiffuess of an SL material at a certain age. The methodology that has been developed in this work can now be further used to predict the mechanical properties of any future Epoxy-based SL material providing the diffusion coefficient(s) of the material are known.

Funding

Innovative Manufacturing Research Centres (IMRC) I Engineering and Physical Sciences Research Council (EPSRC), 3D Systems and Huntsman

History

School

  • Mechanical, Electrical and Manufacturing Engineering

Publisher

© Naguib Saleh

Publisher statement

This work is made available according to the conditions of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) licence. Full details of this licence are available at: https://creativecommons.org/licenses/by-nc-nd/4.0/

Publication date

2005

Notes

A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.

EThOS Persistent ID

uk.bl.ethos.419900

Language

  • en

Usage metrics

    Mechanical, Electrical and Manufacturing Engineering Theses

    Exports

    RefWorks
    BibTeX
    Ref. manager
    Endnote
    DataCite
    NLM
    DC