A series of 24 geometrically and materially non-linear finite element analyses of a simply supported YT tubular joint, with axial loads on the T- and Y-brace ends, was carried out to collapse, using solid three-dimensional element models. The analyses all have proportional and monotonic loading histories (i.e. radial load paths) and each analysis has a different T-brace to Y-brace load ratio so that the series ranges over all four quadrants of the two-dimensional load space. The results of the analyses are processed and combined by means of an energy approach, specifically a generalization of Castigliano's theorem on displacements using the concept of complementary work. A prediction method is thus developed to determine the non-linear, elastic-plastic, force-displacement responses of the joint for arbitrary (in-plane) radial load paths in the two-dimensional load space of the structure. One immediate application envisaged is the development of an elastic-plastic ‘joint finite element’ for use in the collapse prediction of tubular structures. The method is potentially applicable to a range of structures and loading scenarios, including other tubular joint types, both uniplanar and multiplanar, with bending moments and/or torques as well as transverse and axial loads.

An experimental test for measuring the friction between Ti-6Al-4V sheet material and S310 stainless steel tool material at 900 o C is presented. The test is intended for application to Ti-6Al-4V superplastic forming for the manufacture of aeroengine components. The work is motivated by the need for accurate, representative data for process modelling, where accurate simulation is critical to formed component dimensions. The results show a time dependency of friction. The effects of boron nitride density, applied normal load and die surface roughness are investigated.All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of Trans Tech Publications Ltd, www.scientific.net. (Scite.

No abstract

This paper describes an experimental and finite element investigation of the non-linear elastic± plastic force±displacement response of a simply supported tubular YT-joint under a range of ratios of the T-to Y-brace applied loads, in order to develop an understanding of the dependence of the joint response on loading path. The experiments consist of the static testing of simply supported tin±lead alloy models of tubular YT-joints under combined, proportionally applied T-and Y-brace-end axial forces. A number of different finite element approaches are presented and discussed via comparison with the test results. An improved version of the energy-based elastic±plastic prediction procedure of the present authors is presented; this is shown to represent a framework for the determination of the non-linear local joint T-and Y-brace force±displacement responses to arbitrary radial loading paths in the load space. The work is considered relevant to the simplification of tubular framework analysis methods for the calculation of accurate collapse loads, incorporating non-linear joint behaviour.