Rhys Jones [1][2], Ramesh Chandwani [3], Chris Timbrell [3], Anthony J. Kinloch [4], Darren Peng [1][2]
[1] Centre of Expertise for Structural Mechanics, Department of Mechanical and Aerospace Engineering, Monash University, Clayton, VIC 3800, Australia
[2] ARC Industrial Transformation Training Centre on Surface Engineering for Advanced Materials, Faculty of Science, Engineering and Technology, Swinburne University of Technology, John Street, Hawthorn, VIC 3122, Australia
[3] Zentech International Limited, 590B Finchley Road, London NW11 7RX, UK
[4] Department of Mechanical Engineering, Imperial College London, Exhibition Road, London SW7 2AZ, UK

Aerospace 2023, 10(11), 946.

Abstract:
Adhesively bonded doublers and adhesively bonded repairs are extensively used to extend the operational life of metallic aircraft structures. Consequently, this paper focuses on the tools needed to address sustainment issues associated with both adhesively bonded doublers and adhesively bonded repairs to (metallic) aircraft structures, in a fashion that is consistent with the building-block approach mandated in the United States Air Force (USAF) airworthiness certification standard MIL-STD-1530D and also in the United States (US) Joint Services Structural Guidelines JSSG-2006. In this context, it is shown that the effect of biaxial loads on cohesive crack growth in a bonded doubler under both constant amplitude fatigue loads and operational flight loads can be significant. It is also suggested that as a result, for uniaxial tests to replicate the cohesive crack growth seen in adhesively bonded doublers and adhesively bonded repairs under operational flight loads, the magnitude of the applied load spectrum may need to be continuously modified so as to ensure that the crack tip similitude parameter in the laboratory tests reflects that seen in the full-scale aircraft.

Chao Liu [1], Guang-chen Jiao [2], Ramesh Chandwani [3], Chris Timbrell [3]
[1] School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai, PR China
[2] Shanghai Hui Ce Information Technology Co., Ltd, Shanghai, PR China
[3] Zentech International Limited, London, UK

International Journal of Pressure Vessels and Piping, Volume 193, October 2021

Chris Timbrell [1], Ramesh Chandwani [1], Ma Chunlei [2]
[1] Zentech International Limited
[2] Consys Group Limited

ISSI 2018 - Nanjing, China, 2-5 November 2018

Abstract:
Since the industrial revolution when a German mining engineer August Wohler first studied the frequent breaking of chains causing several casualties and developed the concept of what we now know as the S-N curve, many experimental, theoretical and software-aided simulation techniques have been developed to study ageing material behaviour and to design new materials. Over time the demands placed on new materials have required operation under more severe temperatures and loads in order to conserve natural resources and minimise emissions.
Fracture mechanics based finite element algorithms to simulate 3D cracks in components / structures have proved very useful in assessing the residual life and developing repair and maintenance strategies as mandatorily required by various licensing authorities for the continuous operation of infrastructure projects in Aerospace, Power, Transportation, Oil and Chemical industries under the ever more demanding operating conditions. Here one such software tool for crack simulation of industrial applications is presented with examples including combined fatigue and time dependent crack growth under thermo-mechanical loading including hold-time and weld defect assessment with inclusion of dis-similar materials.