Imperial College London
Emeritus Professor Gordon Williams

Emeritus Professor Gordon Williams

Faculty of Engineering, Department of Mechanical Engineering

Academic Visitor
 
 
 
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Contact

 

+44 (0)20 7594 7200g.williams Website

 
 
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Location

 

343City and Guilds BuildingSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
to

302 results found

Williams JG, Hadavinia H, Cotterell B, 2005, Anisotropic elastic and elastic-plastic bending solutions for edge constrained beams, INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES, Vol: 42, Pages: 4927-4946, ISSN: 0020-7683

Journal article

Charalambides MN, Goh SM, Wanigasooriya L, Williams JG, Xiao Wet al., 2005, Effect of friction on uniaxial compression of bread dough, JOURNAL OF MATERIALS SCIENCE, Vol: 40, Pages: 3375-3381, ISSN: 0022-2461

Journal article

Williams JG, 2005, A global energy analysis of impact loaded bi-material strips, Conference on Prospects in Fracture in honor of the 65th Birthday of JG Williams, Publisher: PERGAMON-ELSEVIER SCIENCE LTD, Pages: 813-826, ISSN: 0013-7944

Conference paper

Goh SM, Charalambides MN, Williams JG, 2005, On the mechanics of wire cutting of cheese, Conference on Prospects in Fracture in honor of the 65th Birthday of JG Williams, Publisher: PERGAMON-ELSEVIER SCIENCE LTD, Pages: 931-946, ISSN: 0013-7944

Conference paper

Kinloch AJ, Hadavinia H, Kawashita L, Moore DR, Williams JGet al., 2005, A novel numerical model to analyse elastic-plactic peel tests, Adhesion 2005, Ninth international conference on the science and technology of adhesion and adhesives, 7 - 9 September 2005, St. Catherine's College, University of Oxford, UK, Pages: 188-191

Conference paper

Kawashita LF, Moore DR, Williams JG, 2005, Analysis of peel arm curvature for the determination of fracture toughness in metal-polymer laminates, Journal of Materials Science, Vol: 40, Pages: 4541-4548, ISSN: 0022-2461

Variable angle fixed arm peel and mandrel peel tests were performed on four metal-polymer laminate systems. In total, four polymeric adhesives and three grades of aluminium alloy (AA) substrates were used, enabling a wide range of material properties to be encompassed in the study. Mandrel peel tests provided a direct determination of the plastic bending energy (G(p)) and adhesive fracture toughness (G(a)). For the fixed arm tests, a global energy-balance analysis (ICPeel software) was used to determine G(a) and G(p) analytically. This was done via the calculation of the maximum curvature of the peel arm (1/R-0) and the root rotation angle (theta(0)) from a beam on elastic foundation model. In order to investigate the accuracy of the analytical approach, an experimental method based on high resolution digital photography enabled 1/R-0 and theta(0) to be measured independently. It was then possible to compare these parameters by measurement and by analytical approach (ICPeel software). theta(0) and R-0 relate to the slope and curvature of the peel arm at the debonding front, respectively. In order to measure these parameters, the coordinates of the edge of the peel arm were extracted from each digital photograph, and the slope and curvature were calculated numerically from these curves. The crack tip was then defined as the point of maximum curvature 1/R-0, in accordance with traditional beam theory. It was found that the smoothing in the calculation of first and second derivatives could generate significant errors in the value of theta(0). On the other hand, R-0 was found to be a more robust measurement, with little dependence on smoothing. Nevertheless, on most occasions, the measured values of theta 0 and R-0, as well as the resulting G(a) were shown to be in good agreement with the analytical model. Since the peel fractures were generally cohesive, G(a) was compared with the cohesive fracture toughness (G(c))obtained from Tapered Double Cantilever Beam (TDCB) tes

Journal article

Kawashita LF, Moore DR, Williams JG, 2005, Comparison of peel tests for metal-polymer laminates for aerospace applications, Journal of Adhesion, Vol: 81, Pages: 561-586, ISSN: 0021-8464

Standard peel tests for aerospace laminates based on metal-polymer systems, namely floating-roller and climbing-drum peel methods, have been accommodated in a unified theory of peeling. This theory also accommodates more basic peel tests such as T-peel and fixed-arm peel and also newer methods such as mandrel peel. These five methods have been applied to two aerospace laminate systems to critically examine their use in the determination of adhesive strength. The theory has been used to unify the outputs from the tests in terms of adhesive fracture toughness. In this way, the comparative merits of the methods can be commented on. The validity of the standard methods has been put in doubt because of the absence of a correction for plastic bending energy and also because of the poor conformance of the peel arm to the roller system used in these methods. The unified theory and some measurements of peel-arm curvature help but not completely overcome some of these difficulties. A further complication that arises in peel is a change in the plane of fracture. This reflects a transition from cohesive fracture in the adhesive to an adhesive fracture at the interfaces among adhesive, primer, and substrate. It is likely that such plane-of-fracture phenomena are intrinsic to evaluation of the laminate and that contemplation of cohesive fracture toughness for the adhesive cannot accommodate such events.

Journal article

Kawashita LF, Moore DR, Williams JG, 2005, The measurement of cohesive and interfacial toughness for bonded metal joints with epoxy adhesives, Composite Interfaces, Vol: 12, Pages: 837-852, ISSN: 0927-6440

The types of crack growth in adhesive joints are reviewed and three are identified, namely central cohesive, asymmetric cohesive and interfacial. Test methods for measuring fracture toughness associated with these cracks are then outlined and include a Tapered Double Cantilever Beam (TDCB) test for a central cohesive crack and peel tests on flexible laminates for the other types of crack. In particular, fixed arm and mandrel peel tests are used. Two aerospace adhesives are used to prepare test specimens in order to conduct these tests. For one of these adhesives, all three types of crack growth were recorded and this provided an opportunity to make detailed comparisons of the three associated fracture toughness values. Of particular interest was the use of the mandrel peel method because it enabled a fracture transition (asymmetric cohesive to interfacial fracture) to be observed during the test. The fracture toughness value associated with a central cohesive crack was similar in magnitude to that for an asymmetric cohesive crack. However, the fracture toughness for interfacial fracture was much lower, but similar in magnitude to the expected value of half the fracture toughness from a TDCB test.

Journal article

Kawashita LF, Kinloch AJ, Moore DR, Williams JGet al., 2005, A critical investigation of a mandrel peel method for the determination of adhesive fracture toughness of metal-polymer laminates, Adhesion '5, 9th international conference on the science and technology of adhesion and adhesives, 7 -9 September, St Catherine's College, Oxford, UK, Publisher: IOM Communications Ltd, Pages: 75-78

Conference paper

Goh SM, Charalambides MN, Williams JG, 2004, Characterisation of non-linear viscoelastic foods by the indentation technique, RHEOLOGICA ACTA, Vol: 44, Pages: 47-54, ISSN: 0035-4511

Journal article

Goh SM, Charalambides MN, Williams JG, 2004, Determination of the constitutive constants of non-linear viscoelastic materials, MECHANICS OF TIME-DEPENDENT MATERIALS, Vol: 8, Pages: 255-268, ISSN: 1385-2000

Journal article

Ivankovic A, Pandya KC, Williams JG, 2004, Crack growth predictions in polyethylene using measured traction-separation curves, 2nd International Conference on Fracture and Damage Mechanics, Publisher: PERGAMON-ELSEVIER SCIENCE LTD, Pages: 657-668, ISSN: 0013-7944

Conference paper

Goh SM, Charalambides MN, Williams JG, 2004, Characterisation of non-linear viscoelastic materials via the indentation technique, 14th international congress on rheology, Seoul, Korea, 22 - 27 August 2004, Pages: FB13-1-FB13-3

Conference paper

Kawashita LF, Moore DR, Williams JG, 2004, Use of peel tests in the selection and assessment of metal-polymer laminates for aerospace applications, Proceedings of the 7th structural adhesives in engineering conference, Bristol, July 2004

Conference paper

Kawashita LF, Moore DR, Williams JG, 2004, A comparative study of mandrel assisted peel and fixed arm peel tests on epoxy-metal laminates, 27th annual meeting of the Adhesion Society; from molecules and mechanics to optimization and design of adhesive joints, Wilmington, N.C., February 2004, Publisher: Adhesion Society, Pages: 27-29, ISSN: 1086-9506

Conference paper

Kawashita LF, Moore DR, Williams JG, 2004, Peel tests: Measuring the energy dissipation in plastic bending, 27th annual meeting of the Adhesion Society; from molecules and mechanics to optimization and design of adhesive joints, Wilmington, N.C., February 2004, Publisher: Adhesion Society, Pages: 281-283, ISSN: 1086-9506

Conference paper

Kawashita LF, Moore DR, Williams JG, 2004, The development of a mandrel peel test for the measurement of adhesive fracture toughness of epoxy-metal laminates, Pages: 147-167, ISSN: 0021-8464

A mandrel peel test is established for measuring the adhesive fracture toughness of a metal/rubber-toughened epoxy laminate system. By adopting an energy balance analysis it is possible to determine directly both adhesive fracture toughness and plastic work in bending the peel arm around the mandrel. The suitability of the procedure is examined for various types of metal peel arms, which are classified in terms of their ability to deform plastically during the test. The plastic work is also predicted theoretically, and comparisons are made between the measured and calculated values. The fracture energies determined from the mandrel tests are compared with those obtained from 90degrees fixed-arm peel tests. For the calculations of plastic work in bending in the fixed arm test, various options are used when modelling the tensile stress-strain behaviour of the peel arm material. In addition,the adhesive layer thickness is considered in terms of its influence on the calculation of adhesive fracture toughness.

Conference paper

Kawashita LF, Moore DR, Williams JG, 2004, Influence Of peel arm curvature in the determination of adhesive-fracture toughness of metal-polymer laminates, Proceedings of the 7th European adhesion conference, Freiburg, Germany, September 2004

Conference paper

Goh SM, Charalambides MN, Williams JG, 2004, Experimental and numerical investigation of the wire cutting of cheese, 9th international congress on engineering and food, Montpellier, France, 7 - 11 March 2004, Pages: 228-233

Conference paper

Goh SM, Charalambides MN, Williams JG, 2003, Mechanical properties and sensory texture assessment of cheeses, JOURNAL OF TEXTURE STUDIES, Vol: 34, Pages: 181-201, ISSN: 0022-4901

Journal article

Goh SM, Charalambides MN, Williams JG, 2003, Large strain time dependent behavior of cheese, JOURNAL OF RHEOLOGY, Vol: 47, Pages: 701-716, ISSN: 0148-6055

Journal article

Georgiou I, Hadavinia H, Ivankovic A, Kinloch AJ, Tropsa V, Williams JGet al., 2003, Cohesive zone models and the plastically deforming peel test, Journal of Adhesion, Vol: 79, Pages: 239-265, ISSN: 1545-5823

The peel test is a popular test method for measuring the peeling energy between flexible laminates. However, when plastic deformation occurs in the peel arm(s) the determination of the true adhesive fracture energy, G c , from the measured peel load is far from straightforward. Two different methods of approaching this problem have been reported in recently published papers, namely: (a) a simple linear-elastic stiffness approach, and (b) a critical, limiting maximum stress, † max , approach. In the present article, these approaches will be explored and contrasted. Our aims include trying to identify the physical meaning, if any, of the parameter † max and deciding which is the better approach for defining fracture when suitable definitive experiments are undertaken. Cohesive zone models Fracture mechanics Laminates Peel tests Plastic deformation

Journal article

Blackman BRK, Hadavinia H, Kinloch AJ, Williams JGet al., 2003, The use of a cohesive zone model to study the fracture of fibre composites and adhesively-bonded joints, International Journal of Fracture, Vol: 119, Pages: 25-46, ISSN: 1573-2673

Analytical solutions for beam specimens used in fracture-mechanics testing of composites and adhesively-bonded joints typically use a beam on an elastic foundation model which assumes that a non-infinite, linear-elastic stiffness exists for the beam on the elastic foundation in the region ahead of the crack tip. Such an approach therefore assumes an elastic-stiffness model but without the need to assume a critical, limiting value of the stress,σ max, for the crack tip region. Hence, they yield asingle fracture parameter, namely the fracture energy,G c. However, the corresponding value ofσ max that results can, of course, be calculated from knowledge of the value ofG c. On the other hand, fracture models and criteria have been developed which are based on the approach thattwo parameters exist to describe the fracture process: namelyG candσ max. Hereσ max is assumed to be a critical,limiting maximum value of the stress in the damage zone ahead of the crack and is often assumed to have some physical significance. A general representation of the two-parameter failure criteria approach is that of the cohesive zone model (CZM). In the present paper, the two-parameter CZM approach has been coupled mainly with finite-element analysis (FEA) methods. The main aims of the present work are to explore whether the value ofσ max has a unique value for a given problem and whether any physical significance can be ascribed to this parameter. In some instances, both FEA and analytical methods are used to provide a useful crosscheck of the two different approaches and the two different analysis methods.

Journal article

Ting SKM, Williams JG, Ivankovic A, 2003, Effects of constraint on the traction-separation behaviour of polyethylene, 3rd Conference on Fracture of Polymers, Composites and Adhesives, Publisher: ELSEVIER SCIENCE BV, Pages: 143-154, ISSN: 1566-1369

Conference paper

Blackman BRK, Pavan A, Williams JG, 2003, Fracture of polymers, composites, and adhesives II, London, Publisher: Elsevier, ISBN: 9780080441955

Book

Goh SM, Charalambides MN, Williams JG, 2003, Rheological characterisation of cheese, Zurich, 3rd international symposium on food rheology and structure, Zurich, Switzerland, 9 - 13 February 2003, Publisher: Laboratory of Food Process Engineering, Institute of Food Science and Nutrition, Pages: 267-271

Conference paper

Brunner AJ, Blackman BRK, Williams JG, 2003, Deducing bridging stresses and damage from GIC tests on fibre composites, Oxford, Fracture of polymers, composites and adhesives II, Publisher: Elsevier, Pages: 479-490

Conference paper

Georgiou I, Ivankovic A, Kinloch AJ, Tropsa Vet al., 2003, Rate dependent fracture behaviour of adhesively bonded joints, 3rd Conference on Fracture of Polymers, Composites and Adhesives, Publisher: ELSEVIER SCIENCE BV, Pages: 317-328, ISSN: 1566-1369

Conference paper

Goh SM, Charalambides MN, Williams JG, 2003, Determination of the constitutive constants of non-linear viscoelastic materials, 2003 SEM 4th international conference on mechanics of time dependent materials, 7-10 October 2003, Lake Placid, NY, Pages: 62-62

Conference paper

Brunner AJ, Blackman BRK, 2003, Delamination fracture in cross-ply laminates: what can be learned from experiment?, London, Fracture of polymers, composites and adhesives, Diablerets, Switzerland, September 2002, Publisher: Elsevier, Pages: 433-444

Conference paper

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