Duncan Dowson. 31 August 1928—6 January 2020

After completion of his PhD studies, under Derman Christopherson at Leeds, Duncan Dowson spent most of his life researching in tribology and writing its history. Building on the early studies of Osborne Reynolds and later Russian scientists, he made outstanding contributions to the field of elastohydrodynamic lubrication. This is the science of lubrication in which account is also taken of the deformation of the bearing material. An important parameter is the ratio of the elastrohydrodynamic lubricant film thickness to the bounding surface roughness. This is coupled to considerations of surface deformation and wear. In engines, an important consideration is the use of piston sealing rings to contain the hot combustion gases. Similar lubricant film and wear analyses are applicable to artificial hip and knee joints. A fruitful collaboration developed with the Rheumatism Research Unit at Leeds. and a novel pendulum machine was developed to measure the friction in artificial joints. At that time, low friction in hip joints was achieved with stainless steel components, with high molecular weight polytetrafluoroethylene (PTFE) for the cup. Wear rates at the interfaces were excessive and alternatives continue to be sought, including metal-on-metal joints. This has led to extensive experimental studies of the wear in such joints by Duncan and his colleagues, revealing dependencies upon the metal, its surface roughness and any added lubricants. These experiments included the compatibility of different metals in metal-on-metal joints, their interconnected fluid film roughness and wear rate.