Introduction - Professor Jim Rhodes, Founding Editor

This special edition of the Journal comprises the collection of papers presented at a conference held at the University of Strathclyde, Glasgow, to celebrate the work of Professor Jim Rhodes. The conference theme, Thin Walled Structures, encapsulates the technical field in which Professor Rhodes has been at the forefront for over 40 years. Indeed, it is appropriate that the conference bore the same name as the present Journal, which Professor Rhodes founded in 1983. The special event, held over 2 days, focussed on five specific technical themes, which Professor Rhodes has contributed to over the years, namely Cold Formed Steel (6 papers)-Chaired by Dr. Martin MacDonald, Glasgow Caledonian University; Buckling and Thin Walled Systems (7 papers)-Chaired by Professor Joe Loughlan, Loughborough University; Impact and Dynamical Systems (5 papers)-Chaired by Dr. Marcus Wheel, University of Strathclyde; Composites (5 papers)-Chaired by Professor William M. Banks, University of Strathclyde; Plates and Shells (9 papers)-Chaired by Dr. David Nash, University of Strathclyde

Using finite element method in preoperative planning for wrist surgery

The wrist has a wide variation of 'normal' anatomy, which may explain the discrepancy seen in success rates of some clinical procedures between patients with similar symptoms. Previously published finite element models of the wrist joint have been based on a single geometry and/or single loading condition which does not give a full representation of the spectrum of normal wrists. In this study, three finite element models of the wrist were created and used subject specific boundary conditions thus building a set of models which can be identified as a part of a larger population. Systematic variations in anatomy and bone position were studied and the effect they have on the general load transfer through the normal wrist joint. That information can prove to be important for future surgical planning on the wrist joint

The buckling and collapse behaviour of saddle-supported cylinders - Keynote Lecture

Recent work by the present authors on the collapse conditions for horizontal cylindrical saddle supported storage vessels is described and reviewed. Attention is directed to a range of geometries, typically R/t < 200, where plastic collapse type failure may be relevant. A series of forty tests on end-supported model cylinders loaded centrally by a rigid saddle were performed and a variety of theoretical methods were used for comparison with the test results. It was found that the best agreement was obtained by using an elasticplastic finite element analysis approach. The results of a parametric survey based on the elastic-plastic finite element method are summarised. The paper reports some validation checks, which have been performed to support the parametric results

A parametric study of metal-to-metal contact flanges with optimised geometry for safe stress and no-leak conditions

This paper presents the results of a parametric study of the behaviour of metal-to-metal contact flanges that have different surface profiles. Using a finite element analysis approach, the important stress values in the flange and bolts and flange rotation/displacement have been obtained for variations in flange thickness, bolt pre-stress and taper angle (different surface profiles) whilst maintaining other leading flange dimensions (hub length and hub thickness) constant, when the vessel/flange component is subjected to internal pressure. In addition, results are compared for the flange geometry with no taper angle on the flange surface with the predictions obtained from the appropriate sections of the ASME, PD5500 and new European unfired pressure vessel standard EN 13445 Part 3. Based on the results of this study, the best flange dimensions are recommended for 'no leak' conditions from the joint

Numerical analysis of a sling support arrangement for grp composite pressure vessels

A flexible sling support arrangement for horizontal glass reinforced plastic pressure vessels is examined using advanced finite element methods. A mathematical model is produced employing a suitable analysis capable of representing the non-linear behaviour of a sling supported GRP vessel. This system is used to examine the phenomena occurring at the interface between the vessel and the supporting belt. Each component is initially considered some distance apart and then brought together using three-dimensional contact surfaces. External loads are thereafter applied to the combined model. Although several numerical difficulties arise due to the difference in flexibility between the vessel shell and the sling support, these are overcome and the resulting vessel strains and contact interface pressures show good agreement with experimental work. The magnitudes of the strains at the location of the saddle horn are significantly reduced. Results of a parameter study are also presented which show the effect of the sling position together with the influence of the wrap-round angle and a number of recommendations are made with respect to design

Parametric plastic collapse loads and their validation for horizontal saddle supported storage vessels

In general, progressive plastic collapse occurs in vessels with low values of R/t ratio, typically less than 200, and elastic-plastic buckling is observed in vessels with higher R/t ratios. The aim of this paper is to examine various theoretical analyses for plastic collapse loads, applicable to vessels with low values of R/t ratio, and compare these with the experimental results obtained by the authors and others

Mitigation of welding distortion and residual stresses via cryogenic CO2 cooling - a numerical investigation

Fusion welding remains the most common and convenient fabrication method for large, thinplate welded structures. However, the resulting tendency to out-of-plane distortion exacts severe design and fabrication penalties in terms of poorer buckling performance, lack of fairness in external appearance, poor fit-up and frequent requirements for expensive rework. There are several ways to mitigate welding distortion and this study concentrates on the use of cryogenic CO2 cooling to reduce distortion. A feasible combination of welding process and cooling parameters, was investigated computationally and the resulting effects on final deformation were predicted. Three different computational strategies were developed and applied to butt-welding and fillet-welding processes, with and without the inclusion of cryogenic cooling. In the first method, a fully transient, uncoupled thermo-elastoplastic model was investigated. This method is comprehensive but not readily applicable to predict welding distortions in complex, industrial-scale, welded structures, due to the large computational requirement. More computationally efficient models are needed therefore and two further models of this type are suggested in this study. The results show good agreement between the different models, despite substantial differences in computational budget. In butt-welded plates, a significant decrease in out-of-plane distortion is obtained when cryogenic cooling is applied. In fillet-welded plates, cooling had much less effect on welding distortion. This was largely due to the size and configuration of the test case assemblies and the fact that the attached stiffener greatly increased the overall stiffness and resistance to contraction forces

Loading on the Scapho-Trapezium-Trapezoid joint during gripping

The scapho-trapezium-trapezoid (STT) joint is believed to be highly vulnerable to wear and has been identified clinically as a high risk joint in arthritic patients. A theoretical model [1] of the load transfer through the wrist during gripping, suggests high activity in the STT ligaments in order to stabilize the carpus. During gripping complicated loading patterns are seen in the carpal bones and various intercarpal joints comprising the wrist joint. The aim was to investigate contact stresses at the STT joint in comparison to those occuring at the radiocarpal joint. Finite element model was created of the whole wrist joint with physiological loading conditions applied

On the plastic collapse of horizontal saddle supported storage vessels

The present paper summarises a comprehensive programme of work on collapse loads of horizontal cylindrical saddle supported storage vessels. A programme of tests was conducted on 40 model vessels that included both welded and loose saddles. Different collapse behaviours were observed depending largely on the radius to thickness ratio of the vessels. A range of theoretical approaches were explored and compared with the experimental results. The best theoretical comparison was then used to conduct a parametric survey covering a total of 218 cases. The results of the survey have been presented in the form of simple design graphs

Effects of partial wrist arthrodesis on loading at the radiocarpal joints

The radiocarpal joint plays an important role in the stabilization of the wrist joint. Degenerative diseases such as rheumatoid arthritis can destabilize the joint and compromise the kinematics of the carpal bones. Partial wrist arthrodesis in the rheumatoid wrist has been popular since its introduction in 1983 [1]. The procedure prevents ulnar drift of the carpus and prevents progression to a subluxed state as well as providing pain relief for the patient. The biomechanical consequences of arthrodesis at the radiocarpal joint have not been extensively explored. This study looks at the biomechanical changes on the load transfer through the radiocarpal joint after partial wrist fusion