Browsing by Author "Blacket, S"

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    Feasibility of measuring residual stress profile in different self-pierce riveted joints
    (Maney Publishing, 2012-01-01) Haque, R; Beynon, JH; Durandet, Y; Kirstein, O; Blacket, S
    The feasibility of measuring residual stresses in self-pierce riveted (SPR) joints by neutron diffraction technique was investigated. The main challenge involved dealing with the very small dimensions of SPR joints. Two different joints were examined: aluminium‐steel and steel‐steel. Even though small dimensions were involved, meaningful results were obtained. In the rivet head, tensile stress was observed for the steel‐steel sample, whereas only compressive stress was observed for the aluminium‐steel. The residual stress in the rivet head was higher at the centre and lower at the edge for both joints. Stresses in the sheet material beside the rivet wall and at a distance of three times the rivet radius from the rivet axis were not significant. For the SPR joints examined, the maximum value of residual stress was compressive and occurred in the rivet leg. The results are discussed according to the physical events involved during the process.© 2012, Maney Publishing
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    Optimising parameters for meaningful measurement of residual strain by neutron diffraction in self-pierce riveted joints
    (Maney Publishing, 2013-11-18) Haque, R; Durandet, Y; Wong, YC; Paradowska, AM; Beynon, JH; Blacket, S
    The aim of this work is to examine the uncertainties involved in measuring residual strain and their dependence on both the gauge volume of the neutron beam and the acquisition time in self pierce riveted (SPR) joints while using the neutron diffraction technique. The main challenge involved dealing with the very small dimensions of SPR joints and developing optimum instrument configuration that allowed faster and/or more accurate stress measurement in SPR while maintaining the same time resolution required for the millimetre scale of the problem. Two different gauge volumes were used (0.125 and 1.0 mm(3)), and two different measuring directions were chosen in order to examine the rotational accuracy of the sample table. All measurements were conducted in steel–steel joints. Even though small sizes were involved, meaningful results were obtained and measurement errors were reduced by optimising the instrument parameters. © 2013, Maney Publishing
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    SPR characteristics curve and distribution of residual stress in self-piercing riveted joints of steel sheets
    (Hindawi, 2017-02-15) Haque, R; Wong, YC; Paradowska, AM; Blacket, S; Durandet, Y
    Neutron diffraction was used to describe the residual stress distributions in self-piercing riveted (SPR) joints. The sheet material displayed a compressive residual stress near the joint, and the stress gradually became tensile in the sheet material far away from the joint. The stress in the rivet leg was lower in the thick joint of the softer steel sheet than in the thin joint of the harder steel sheet. This lower magnitude was attributed to the lower force gradient during the rivet flaring stage of the SPR process curve. This study shows how the residual stress results may be related to the physical occurrences that happened during joining, using the characteristics curve. The study also shows that neutron diffraction technique enabled a crack in the rivet tip to be detected which was not apparent from a cross-section. © 2017 Rezwanul Haque et al. This is an open access article distributed under the Creative Commons Attribution License